02_RN31552EN10GLA0_The Physical Layer

The Physical Layer3GRPLS (RN3155) – Module 2

Part I: Channel Mapping

Part II: Transport Channel Formats

1 © Nokia Siemens Networks RN31552EN10GLN0

Part II: Transport Channel Formats

Part III: Cell Synchronisation

Part IV: Common Control Physical Channels

Part V: Physical Random Access

Part VI: Dedicated Physical Channel Downlink

Part VII: Dedicated Physical Channel Uplink

Part VIIII: HSDPA Physical Channel (HS-PDSCH)

Part IX: HSUPA Physical Channels (E-DCH)

At the end of this module, you will be able to

• Describe the WCDMA channel structure including their mutual mapping• Explain transport channel format• List different code types

• Name the main differences in uplink and downlink data organisation

• Describe the UE cell synchronisation

Objectives


• Describe the UE cell synchronisation• Outline the paging organisation and its impact on the UE• Characterise the random access, its power power control and code planning

• Describe the DPCHs, their power control, time organisation, and L1

synchronisation• Describe the HS-DSCH and other physical channels related to HSDPA

• Name the different HSDPA physical channel types• What kind of enhancements are implemented with HSUPA ?• Describe the E-DCH capabilities

Part I Channel Mapping


• In GSM, we distinguish between logical and physical channels. In UMTS there are three different

types of channels:

1. Logical

2. Transport

3. Physical

• Logical Channels• Logical Channels were created to transmit a specific content.

• There are for instance logical channel to transmit the cell system information, paging information,

or user data.

• Logical channels are offered as data transfer service by the Medium Access Control (MAC) layer

Radio Interface Channel Organisation


• Logical channels are offered as data transfer service by the Medium Access Control (MAC) layer

to the next higher layer.

• Consequently, logical channels are in use between the mobile phone and the RNC.

• Transport Channels (TrCH)• The MAC layer is using the transport service of the lower lower, the Physical layer.

• The MAC layer is responsible to organise the logical channel data on transport channels. This

process is called mapping.

• In this context, the MAC layer is also responsible to determine the used transport format.

• The transport of logical channel data takes place between the UE and the RNC.

• Physical Channels (PhyCH)•The physical layer offers the transport of data to the higher layer.

•The characteristics of the physical transport have to be described.

•When we transmit information between the RNC and the UE, the physical medium is changing.

•Between the RNC and the Node B, where we talk about the interface Iub, the transport of

information is physically organised in so-called Frames.

•Between the Node B and the UE, where we find the WCDMA radio interface Uu, the physical

transmission is described by physical channels.

•A physical channel is defined by the UARFCN and the a spreading code in the FDD mode.

Radio Interface Channel Organisation


Logical Channelscontent is organised in separate channels, e.g.

System information, paging, user data, link management

Radio Interface Channel Organisation (R99 model)


Transport Channelslogical channel information is organised on transport channel

resources before being physically transmitted

Physical Channels(UARFCN, spreading code)

FramesIub interface

There are two types of logical channels (FDD mode):

1) Control Channels (CCH):

• Broadcast Control Channel (BCCH)•System information is made available on this channel.

•The system information informs the UE about the serving PLMN, the serving cell, neighbourhood

lists, measurement parameters, etc.

•This information permanently broadcasted in the downlink.

• Paging Control Channel (PCCH)•Given the BCCH information the UE can determine, at what times it may be paged.

•Paging is required, when the RNC has no dedicated connection to the UE.

Logical Channels


•Paging is required, when the RNC has no dedicated connection to the UE.

•PCCH is a downlink channel.

• Common Control Channel (CCCH)•Control information is transmitted on this channel.

•It is in use, when no RRC connection exists between the UE and the network.

•It is a bi-directional channel, i.e. it exists both uplink and downlink.

• Dedicated Control Channel (DCCH)•Dedicated resources were allocated to a UE.

•These resources require radio link management, and the control information is transmitted both

uplink and downlink on DCCHs.

• 2) Traffic Channels (TCH):

• Dedicated Traffic Channel (DTCH)•User data has to be transferred between the UE and the network.

•Therefore dedicated resources can be allocated to the UE for the uplink and downlink user data

transmission.

• Common Traffic Channel (CTCH)•Dedicated user data can be transmitted point-to-multipoint to a group of UEs.

Logical Channels


Logical Channels are mapped onto Transport Channels. There are two types of Transport Channels

(FDD mode):

a) Common Transport Channels:

• Broadcast Channel (BCH)It carries the BCCH information.

• Paging Channel (PCH)It is in use to page a UE in the cell, thus it carries the PCCH information. It is also used to notify UEs

about cell system information changes.

• Forward Access Channel (FACH)The FACH is a downlink channel. Control information, but also small amounts of user data can be

Transport Channels (TrCH)


The FACH is a downlink channel. Control information, but also small amounts of user data can be

transmitted on this channel.

• High Speed Downlink Shared Channel (HS-DSCH)A downlink channel shared between UEs by allocation of individual codes, from a common pool of

codes assigned for the channel or by allocating different time.

• Random Access Channel (RACH)This uplink channel is used by the UE, when it wants to transmit small amouts of data, and when the

UE has no RRC connection. It is often used to allocated dedicated signalling resources to the UE to

establish a connection or to perform higher layer signalling. It is a contention based channel, i.e.

several UE may attempt to access UTRAN simultaneously.

b) Dedicated Transport Channels:

• Dedicated Channel (DCH)Dedicated resources can be allocated both uplink and downlink to a UE. Dedicated resources are

exclusively in use for the subscriber.

• Enhanced Dedicated Channel (E-DCH)The E-DCH is a resource that exists in uplink only, when HSUPA is in use. It has only impact on the

physical and transport channel levels, it is not visible in the logical channels provided by MAC. The E-

DCH is a transport channel that is subject to Node-B scheduling. The E-DCH is defined as an

extension to DCH transmission.

Transport Channels (TrCH)


• On the following figures. you can see the mapping of logical channels onto transport channels, as well

as the mapping of transport channels onto physical channels.

• Note: DSCH (FDD), CPCH removed from R5 specification, 25.301 v5.6.0

• Physical Channels are characterised by

•UARFCN,

•scrambling code,

•channelisation code (optional),

•start and stop time, and

•relative phase (in the uplink only, with relative phase being 0 or π/2)

• Transport channels can be mapped to physical channels.

• But there exist physical channels, which are generated at the Node B only, as can be seen on the next

Physical Channels (PhyCH)


• But there exist physical channels, which are generated at the Node B only, as can be seen on the next

figures.

• The details of the physical channels is described in detail within this module (see following pages).

• Note: PDSCH and PCPCH removed from R5 specification, 25.301 v5.6.0

P-CCPCHPCH

BCH

PCCH

BCCH CPICH

S-SCH

P-SCH

S-CCPCH

LogicalChannels

TransportChannels

PhysicalChannels

Channel Mapping DL (Network Point of View)


CTCH

DCCH

CCCH

DCH

FACH

HS-DSCH

AICH

HS-PDSCH

DPDCH

S-CCPCH

DTCH

PICH

E-AGCH

HS-SCCH

F-DPCH

E-RGCH

E-HICH

DCCH

LogicalChannels

TransportChannels

PhysicalChannels

RACH

CCCH PRACH

Channel Mapping UL (Network Point of View)


DCCH

DCH

DPDCH

DTCH

DPCCH

E-DPCCH

E-DPDCHE-DCH

Channel configuration examples

AMR call

The data transferred during AMR call consists of

• Speech data

• L3 signalling

• L1 signalling

User data is transferred on DTCH logical channel

Real time connection uses always DCH transport channel


Real time connection uses always DCH transport channel

DCH transport channel is mapped on DPCH (DPDCH + DPCCH)

AMR + PS call (multirab)

Additional stream of user data

• NRT data

Also configurations with HS-DSCH possible

NRT PS call

Different configurations utilising DCH, FACH/RACH, HS-DSCH or HS-DSCH/E-DCH possible

Example – Channel configuration during call

LogicalChannels

TransportChannels

PhysicalChannels

Data

DCCH0-4

DPDCH

RRCsignalling

DCH1


DCH2-4DTCH1 DPCCHSpeech

data

AMR speech connection utilises multiple transport channelsRRC connection utilises multiple logical channels

DCH5DTCH2

NRT

data

AMR speech+

NRT data

This page was intentionally left empty.

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Part IITransport Channel Formats


Transport Channel Formats

Transport Channels are used to exchange data between the MAC-layers in the UE and the RNC.

The data is hereby organised in Transport Blocks (TB). A Transport Block is the basic data unit.

The MAC layer entities use the services offered to them by the Physical layer to exchange Transport Blocks.

One Transport Block can be transmitted only over one Transport Channel. Several Transport Blocks can be simultaneously transmitted via a Transport Channel in one transport data unit to increase the transport efficiency.

The set of all Transport Blocks, transmitted at the same time on the same transport channel


The set of all Transport Blocks, transmitted at the same time on the same transport channel (between the MAC layer and the physical layer) is referred to as Transport Format Set (TFS).

Transport Blocks and Transport Block Sets are characterised by a set of attributes:

• Transport Block Size– The transport block size specifies the numbers of bits of one Transport Block.

– If several Transport Blocks are transmitted within one TBS, then all TBs have the same size.

– Please note, that the transport block size among different TBSs – which are transmitted at different times on one transport channel - can vary.

• Transport Block Set Size– This attribute identifies the numbers of bits in one TBS.

– It must be always a multiple of the transport block size, because all TBs transmitted in one TBS have the same size.

MAC Layer MAC Layer

TBSTransport Channel

UE Node B RNC

TBS

The Transfer of Transport Blocks


PHY Layer PHY LayerL1

FP/AAL2

L1

FP/AAL2

TFI

TBS

TTI radio frames in use

TFI

TBS

Transport Blocks and Transport Block Sets are characterised by a set of attributes (continued):

• Transmission Time Interval (TTI)•The TTI specifies the transmission time distance between two subsequent TBSs, transferred

between the MAC and the PHY layer.

•In the PHY layer, the TTI also identifies the interleaving period. Following TTI periods are

currently specified:

- 2 ms (HS-DSCH)

- 10 ms,

- 20 ms,

- 40 ms, and

- 80 ms



- 80 ms

• Error Protection Scheme•When data is transmitted via a wireless link, it faces a lot of distortion and can thus easily

corrupted.

•Redundancy is added to the user data to reduce the amount of losses on air.

•In UMTS, three error protection schemes are currently specified:

•convolutionary coding with two rates: 1/2 and 1/3,

•turbo coding (rate 1/3), and

•no channel coding (this coding type is scheduled for removal from the UMTS

specifications).

• Size of CRC•CRC stands for cyclic redundancy check. Each TBS gets an CRC.

•The grade of reliability depends on the CRC size, which can be 0, 8, 12, 16, and 24 bits.

DCH 2TB TB TB

TFCS

TTI TTI TTI

TB

TB

TB

Transport Formats


TB Transport Block TF Transport FormatTBS Transport Block Set TFS Transport Format Set

TFC Transport Format CombinationTFCS Transport Format Combination Set

DCH 1

TB

TB

TB

TB

TB

TBS

TF

TFS

TFC

TTITTITTI

TB

• The above description refers to a situation, where the MAC-layer hands the TBS to the PHY layer.

This happens in the UE. But TBSs are normally exchanged between the UE and the RNC. As a

consequence, the TBS must be transmitted over an AAL2 virtual channel between the RNC and the

Node B. The TBS is packet into a frame protocol defined for the traffic channel.

• Different TBSs can be transmitted in one Transport Channel.

• How do MAC and PHY layer know, what kind of TBS they exchanged?

• When a transport channel is setup – or modified – the allowed Transport Block Sets are specified.

• Each allowed TBS gets a unique Transport Format Indicator (TFI).• All TFIs of a Transport Channel are summarised in the Transport Format Set (TFS).



• All TFIs of a Transport Channel are summarised in the Transport Format Set (TFS).• The TF consists of two parts (FDD mode):

•Semi-static part•The attributes belonging to the semi-static part are set by the RRC-layer.

•They are valid for all TBSs in the Transport Channel.

•Semi-static attributes are the Transmission Time Interval (TTI), the error correction

scheme, the CRC size, and the static rate matching parameter (used by the PHY layer for

dynamic puncturing if the TBS is too long for the radio frame).

•Dynamic part•The dynamic part comprises attributes, which can be changed by the MAC layer

dynamically.

•The affected attributes are the Transport Block Size and the Transport Block Set Size.

MAC Layer

RRC Layer

configura

tion

Semi-Static Part• TTI

• Channel Coding

• CRC size

• Rate matching

Dynamic Part

Transport Format

TrCHs

Transport Formats


PHY Layerconfigura

tion

Dynamic Part• Transport Block Size

• Transport Block Set Size

Example: semi-static partdynamic part:- TTI = 10 ms- turbo coding - transport block size: 64 64 64 128- CRC size = 0 - transport block set size: 1 2 4 2- ...

TFI1 TFI2 TFI3 TFI4TrCH: Transport Channel

• The PHY layer can multiplex several Transport Channels in one “internal“ Transport Channel, called

Coded Composite Transport Channel (CCTrCH).

• This CCTrCH can be transmitted on one or several physical channels. Consequently, the TCSs of

different Transport Channels can be found in one radio frame.

• The Transport Format Combination Set (TFCS) lists all allowed Transport Format Combinations

(TFC).

• A Transport Format Combination Indicator (TFCI) is then used to indicate, what kind of Transport

Format Combination is found on the radio frame. You can find TFCI-fields for instance in the S-



Format Combination is found on the radio frame. You can find TFCI-fields for instance in the S-

CCPCH. The TFCS is set by the RRC protocol.

• The table on the following slide lists the allowed Transport Formats for the individual Transport

Channels (FDD mode only).

1...5000 bitsgranularity: 1 bit

246 bits 246 bits


20 ms

10 ms

BCH

PCH

convolutional 1/2

convolutional 1/2

16

0, 8, 12, 16 & 24

Transport Block Size

Transport Block Set Size

TTIcoding types

and ratesCRCsize

Semi-static PartDynamic Part

Transport Format Ranges








10, 20, 40 & 80 ms

10 & 20ms

10, 20, 40 & 80 ms

FACH

RACH

DCH

convolutional 1/2& 1/3; turbo 1/3

convolutional 1/2

convolutional 1/2& 1/3; turbo 1/3

0, 8, 12, 16 & 24

0, 8, 12, 16 & 24

0, 8, 12, 16 & 24

(based on TS 25.302 V5.9.0)

Transport Channel Formats – HS-DSCHThe MAC layer is split to MAC-d and MAC-hs for HS-DSCH

The HS-DSCH is terminated in the BTS (so called MAC-hs)

MAC-hs layer is in charge of

• distributing the HS-DSCH resources between all the MAC-d flows according to their priority (i.e. Packet Scheduling)

• selecting the appropriate transport format for every TTI (i.e. link adaptation)

The radio interface layers above the MAC are not modified from the Release 99 architecture because HSDPA is intended for transport of logical channels

The move of the data queues to the Node B creates the need of a flow control mechanism


The move of the data queues to the Node B creates the need of a flow control mechanism (HS-DSCH Frame Protocol) that aims at keeping the buffers full

The HS-DSCH FP handles the data transport from the serving RNC to the controlling RNC (if the Iur interface is involved) and between the controlling RNC and the Node B

In RAN side MAC-c/sh entity can be involved on HS-DSCH traffic (optional). The following functionality is covered:

• Flow control;

– flow control function also exists towards MAC-hs in case of configuration with MAC-c/sh.

• There is one MAC-c/sh entity in the UTRAN for each cell

MAC -sh is used to control the flow of all MAC-d flows of one BTS for preventing the congestion of the MAC-d data flows inside the RNC and Iub

MAC-d MAC-d

UENode B RNC

The Transfer of Transport Blocks – HS-DSCH

MAC-d PDU

MAC-d


MAC-hsMAC-hs

PHY Layer PHY LayerL1

FP/AAL2

L1

FP/AAL2

HS-

DSCH

MAC-d PDU

TFI

TBS

TFI

TBS

TFI

TBS

FP/HS-DSCH FP/HS-DSCH

MAC-c/sh

OP

TIO

NA

L

HS-PDSCH

Flow

Control

Transport Format for HS-DSCH

Attributes of the dynamic part are:

• Transport block size (same as Transport block set size)

• Redundancy version/Constellation

• Modulation scheme

Attributes of the semi-static part are:

• no semi-static attributes are defined.

Attributes of the static part are:


Attributes of the static part are:

• Transmission time interval. The Transmission time interval is fixed to 2ms in FDD

• Error protection scheme to apply:

– Type of error protection is turbo coding; coding rate is 1/3;

• Size of CRC is 24 bits.

BTS (LA/PS) decides then the used TBS and signals that information to the UE in HS-SCCH with 6bits (TFRI)

MAC-d Layer

RRC Layer

configura

tion

Static Part• TTI

• Channel Coding

• CRC size

Dynamic Part• Transport block size (same as

Transport Format

Transport Formats – HS-DSCH

MAC-hs Layer


PHY Layerconfigura

tion

• Transport block size (same as

Transport block set size)


• Modulation scheme

Example: static part dynamic part:- TTI = 2 ms- turbo coding - transport block size: 357 4420 1711 699- CRC size = 24 - modulation: QPSK 16-QAM 16-QAM QPSK

TFRI1 TFRI2 TFRI3 TFRI4

HS-DSCH

MAC-hs Layer

TFRI; Transport Format and Resource Indicator

Transport Format for HS-DSCH

1 to 200 000 bitsgranularity: 8 bit

= Transport Block Size

2 msHS-DSCH turbo 1/3 24

Transport Block Size

Transport Block Set Size

TTIcoding types

and ratesCRCsize

Static PartDynamic Part

QPSK,16-QAM

Modulation

1 to 8

Redundancyversion


The instantaneous data rate range supported is (determined on a per-2ms interval):

• A TBS of 137 bits corresponding to 68.5 kbps (single code, QPSK, strong coding)

• A TBS of 28457 bits corresponding to 14.228 Mbps (15 codes, 16QAM, very low coding)

Transport Channel Formats – E-DCH

New MAC entities appear as follows for each network element:

UENew MAC entity (MAC-es/MAC-e) is added in the UE located below MAC-d. and is in charge of:

• H-ARQ: buffering MAC-e payloads & retransmit ting them

• Multiplexing: concatenating multiple MAC-d PDUs to MAC-es PDUs & multiplex 1 or multiple MAC-es PDUs to 1 MAC-e PDU

• E-TFC selection: Enhanced Transport Format Combination selection according to scheduling information (Relative & Absolute Grants) received from UTRAN via L1.

Node BNew MAC entity (MAC-e) is added in Node B which handles:

•


• HARQ retransmissions: generating ACKs/NACKs

• E-DCH Scheduling: manages E-DCH cell re sources between UEs; implementation proprietary

• E-DCH Control: receives scheduling requests & transmits scheduling assignments.

• MAC-e PDUs de-multiplexing

S-RNCNew MAC entity (MAC-es) is added in the SRNC in order to perform:

• Reordering: reorders received MAC-es PDUs according to the received TSN

• Macro diversity selection: for SHO (Softer HO in Node-B); delivers received MAC-es PDUs from each Node B of E-DCH AS; see reordering function

• Disassembly: Remove MAC-es header,extract MAC-d PDU’s & deliver to MAC-d

UE Node B

The Transfer of Transport Blocks – E-DCH

S-RNC modifications:

MAC-es handling:

• in-sequence delivery (reordering)

Node B modifications:

MAC-e handling:

UE modifications:

MAC-es & MAC-e:

• H-ARQ retransmission

S-RNC


PHY

MAC-es / MAC-e

MAC-d

PHY

MAC-e

PHY

E-DCH FP Uu

RLC

• in-sequence delivery (reordering)

• SHO data combining

MAC-e handling:


• Scheduling & MAC-e multiplexing


• Scheduling & MAC-e multiplexing

• E-DCH TFC selection

PHY

MAC-es

MAC-d

E-DCH FPIub

RLC

Transport Format for E-DCH & UE capability classes

E- DCH

Category

max.

E-DCH

Codes

min.

SF

2 & 10 ms

TTI E-DCH

support

max. #. of

E-DCH Bits* /

10 ms TTI

max. # of

E-DCH Bits* /

2 ms TTI

Reference

combination

Class

1 1 4 10 ms only 7110 - 0.73 Mbps

2 2 4 10 & 2 ms 14484 2798 1.46 Mbps

3 2 4 10 ms only 14484 - 1.46 Mbps


4 2 2 10 & 2 ms 20000 5772 2.92 Mbps

5 2 2 10 ms only 20000 - 2.0 Mbps

6 4 2 10 & 2 ms 20000 11484 5.76 Mbps

• “Dual-branch BPSK” (resulting in QSPK output) is the only modulation used in HSUPA (Rel. 6)

•There can only be 1 transport block in each TTI, →Transport block size = Transport Block Set Size

•Coding types and rates: Turbo coding 1/3

Note: When 4 codes are transmitted in parallel, two codes shall be transmitted with SF2 and two with SF4

* Maximum No. of bits / E-DCH transport block

MAC-d Layer

RRC Layer

configura

tion

Static Part• TTI (2ms, 10ms)

• Channel Coding

• CRC size

• Modulation (always BPSK)

Dynamic Part• Transport block size (same as

Transport Format

Transport Formats – E-DCH

MAC-es/MAC-e Layer


PHY Layerconfigura

tion

• Transport block size (same as

Transport block set size)


Example: static part dynamic part:- TTI = 2 ms, 10 ms- turbo coding - transport block size: 357 2420 1711 699- CRC size = 24 BPSK BPSK BPSK BPSK

TFRI1 TFRI2 TFRI3 TFRI4

E-DCH

MAC-es/MAC-e Layer

Example: Transport Formats in AMR call

The AMR codec was originally developed and standardized by the European Telecommunications Standards Institute (ETSI) for GSM cellular systems. It has been chosen by the Third Generation Partnership Project (3GPP) as the mandatory codec for third generation (3G) cellular systems. It supports 8 encoding modes with bit rates between 4.75 and 12.2 kbps.

Feature of the AMR codec is Unequal Bit-error Detection and Protection (UED, UEP).

The UEP/UED mechanisms allow more speech over a lossy network by sorting the bits into perceptually more and less sensitive classes (A, B, C).

• A frame is only declared damaged and not delivered if there are bit errors found in the


• A frame is only declared damaged and not delivered if there are bit errors found in the most sensitive bits (Class A).

• Acceptable speech quality results if the speech frame is delivered with bit errors in the less sensitive bits (Class B, C). Decoder uses error concealment algorithm to hide the errors.

On the radio interface, one Transport Channel is established per class of bits i.e. DCH A for class A, DCH B for class B and DCH C for class C. Each DCH has a different transport format combination set which corresponds to the necessary protection for the corresponding class of bits as well as the size of these class of bits for the various AMR codec modes.

Example: Transport Formats in AMR call

DCH 1: AMR class A bits

TTI = 20 ms

DCH 2: AMR class B bits

DCH 3: AMR class C bits

Convolutional coding

Coding rate: third

TTI = 20 ms

Coding type: convolutional

Coding rate: third

CRC size: 12 bits CRC size: 0 bits CRC size: 0 bits

TTI = 20 ms

Coding rate: half

Convolutional coding

DCH 24: RRC Connection

TTI = 40 ms

Coding type: convolutional

Coding rate: third

CRC size: 16 bits

TBS size:1TB size: 81 bits


TBS size: 1TB size: 39 bits

(SID)

TBS size = 0(DTX)

TBS size: 1TB size: 103 bits

TBS size = 0(DTX)

TBS size = 0(DTX)

TBS size = 1TB size: 148 bitsTBS size: 1

TB size: 60 bits

TBS size = 0(DTX)

12.2 kbit/s3.7 kbit/s


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Part IIICell Synchronisation


Cell SynchronisationWhen a UE is switched on, it starts to monitor the radio interface to find a suitable cell to camp on but it has to determine, whether there is a WCDMA cell nearby.

If a WCDMA cell is available, the UE has to be synchronised to the downlink transmission of the system information – transmitted on the physical channel P-CCPCH – before it can make a decision, in how far the available cell is suitable to camp on.

Initial cell selection is not the only reason, why a UE wants to perform cell synchronisation. This process is also required for cell re-selection and the handover procedure.

Cell synchronisation is achieved I three phases• Step 1: Slot synchronisation

– During the first step of the cell search procedure the UE uses the SCH"s primary synchronisation code to acquire slot synchronisation to a cell. This is typically done with a single matched filter (or any similar device) matched to the primary synchronisation code which is common to all cells. The slot timing of the cell can be obtained by detecting peaks in the matched filter output.


detecting peaks in the matched filter output.

• Step 2: Frame synchronisation and code-group identification

– During the second step of the cell search procedure, the UE uses the SCH"s secondary synchronisation code to find frame synchronisation and identify the code group of the cell found in the first step. This is done by correlating the received signal with all possible secondary synchronisation code sequences, and identifying the maximum correlation value. Since the cyclic shifts of the sequences are unique the code group as well as the frame synchronisation is determined.

• Step 3: Scrambling-code identification

– During the third and last step of the cell search procedure, the UE determines the exact primary scrambling code used by the found cell. The primary scrambling code is typically identified through symbol-by-symbol correlation over the CPICH with all codes within the code group identified in the second step. After the primary scrambling code has been identified, the Primary CCPCH can be detected. And the system- and cell specific BCH information can be read.

If the UE has received information about which scrambling codes to search for, steps 2 and 3 above can be simplified.

Cell Synchronisation

Detect cells

Acquire slot synchronisation

Phase 1 – P-SCH

Phase 2 – S-SCH

Acquire frame synchronisation


Phase 2 – S-SCH

Phase 3 – P-CPICH

synchronisation

Identify the code group of the cell found in the first step

Determine the exact primary scrambling code used by the found cell

Measure level & quality of the found cell

• Cell synchronisation is achieved with the Synchronisation Channel (SCH). This channel divides up

into two sub-channels:

• Primary Synchronisation Channel (P-SCH)•A time slot lasts 2560 chips.

•The P-SCH only uses the first 10% of a time slot.

•A Primary Synchronisation Code (PSC) is transmitted the first 256 chips of a time slot. This is the

case in every UMTS cell.

•If the UE detects the PSC, it has performed TS and chip synchronisation.



(continued on the next text slide)

CP CP

2560 Chips 256 Chips

CP CP CP

Primary Synchronisation Channel (P-SCH)

Secondary Synchronisation Channel (S-SCH)

Synchronisation Channel (SCH)


Cp = Primary Synchronisation CodeCs = Secondary Synchronisation Code

10 ms Frame

Cs1 Cs2 Cs15

Slot 0 Slot 1 Slot 14

Cs1


Slot 0



The S-SCH also uses only the first 10% of a timeslot

Secondary Synchronisation Codes (SSC) are transmitted.

There are 16 different SSCs, which are organised in a 10 ms frame (15 timeslots) in such a way, that the beginning of a 10 ms frame can be


timeslots) in such a way, that the beginning of a 10 ms frame can be determined, and 64 different SSC combinations within a 10 ms frame are identified.

There is a total of 512 primary scrambling codes, which are grouped in 64 scrambling code families, each family holding 8 scrambling code members.

The 15 SSCs in one 10 ms frame identify the scrambling code family of the cell‘s downlink scrambling code.

15

15

scramblingcode group

group 00

group 01

group 02

group 03

group 04

1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

1 2 1 15 5 5 12 16 6 11 2 16 11 12

1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

1 2 16 6 6 11 5 12 1 15 12 16 11 2

slot number

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

11 11

11 11

15

15

15 15

15

155

SSC Allocation for S-SCH


group 05

group 62

group 63

1 3 4 7 4 1 5 5 3 6 2 8 7 6 8

9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

11

11 11

11 11

15

15 15

15 15

5

I monitor the S-SCH

• With the help of the SCH, the UE was capable to perform chip, TS, and frame synchronisation.

•Even the cell‘s scrambling code group is known to the UE.

• But in the initial cell selection process, it does not yet know the cell‘s primary scrambling code.

• There is one primary scrambling code in use over the entire cell, and in neighbouring cells, different

scrambling codes are in use.

•There exists a total of 512 primary scrambling codes.

• The CPICH is used to transmit in every TS a pre-defined bit sequence with a spreading factor 256.

•The CPICH divides up into a mandatory Primary Common Pilot Channel (P-CPICH) and optional

Secondary CPICHs (S-CPICH).

• The P-CPICH is in use over the entire cell and it is the first physical channel, where a spreading code

is in use.

Common Pilot Channel (CPICH)


is in use.

•A spreading code is the product of the cell‘s scrambling code and the channelisation code.

•The channelisation code is fixed: Cch,256,0. i.e., the UE knows the P-CPICH‘s channelisation code,

and it uses the P-CPICH to determine the cell‘s primary scrambling code by trial and error.

• The P-CPICH is not only used to determine the primary scrambling code. It also acts as:-

•phase reference for most of the physical channels,

•measurement reference in the FDD mode (and partially in the TDD mode).

• There may be zero or several S-CPICHs. Either the cell‘s primary scrambling code or its secondary

scrambling codes can be used. In contrast to the P-CPICH, it can be broadcasted just over a part of

the cell.

CP



P-CPICH

10 ms Frame

Primary Common Pilot Channel (P-CPICH)


applied speading code =

cell‘s primary scrambling code ⊗⊗⊗⊗ Cch,256,0

• Phase reference• Measurement reference

P-CPICH

Cell scrambling code? I get it with

trial & error!

• The UE has to perform a set of L1 measurements, some of them refer to the CPICH channel:

• CPICH RSCP• RSCP stands for Received Signal Code Power.

• The UE measures the RSCP on the Primary-CPICH.

• The reference point for the measurement is the antenna connector of the UE.

• The CPICH RSCP is a power measurement of the CPICH.

• The received code power may be high, but it does not yet indicate the quality of the received

signal, which depends on the overall noise level.

• UTRA carrier RSSI.• RSSI stands for Received Signal Strength Indicator.

• The UE measures the received wide band power, which includes thermal noise and receiver

CPICH as Measurement Reference


• The UE measures the received wide band power, which includes thermal noise and receiver

generated noise.

• The reference point for the measurements is the antenna connector of the UE.

• CPICH Ec/No• The CPICH Ec/No is used to determine the “quality“ of the received signal.

• It gives the received energy per received chip divided by the band‘s power density.

• The “quality“ is the primary CPICH‘s signal strength in relation to the cell noise.

• (Please note, that transport channel quality is determined by BLER, BER, etc. )

• If the UE supports GSM, then it must be capable to make measurements in the GSM bands, too. The

measurements are based on the GSM carrier RSSI

• The wideband measurements are conducted on GSM BCCH carriers.

Received Signal Code Power (in dBm)CPICH RSCP

received energy per chip divided by the power density in the band (in dB)CPICH Ec/No

received wide band power, including thermal noise and noise generated in the

receiver

UTRA carrier RSSI

CPICH Ec/No = CPICH RSCP

UTRA carrier RSSI

P-CPICH as Measurement Reference


CPICH Ec/No

0: < -241: -23.52: -233: -22.5...47: -0.548: 049: >0

Ec/No values in dB

CPICH RSCP

-5: < -120-4: -119:0: -1151: -114:89: -2690: -2591: ≥ -25RSCP values in dBm

GSM carrier RSSI

0: -1101: -1092: -108:71: -3972: -3873: -37

RSSI values in dBm

• The UE knows the cell‘s primary scrambling code.

• It now wants to gain the cell system information, which is transmitted on the physical channel P-

CCPCH.

• The channelisation code of the P-CCPCH is also known to the UE, because it must be Cch,256,1 in

every cell for every operator.

• By reading the cell system information on the P-CCPCH, the UE learns everything about the

configuration of the remaining common physical channels in the cell, such as the physical channels for

paging and random access.

• As can be seen from the P-CCPCH‘s channelisation code, the data rate for cell system information is

fixed.

• The SCH is transmitted on the first 256 chips of a timeslot, thus creating here a peak load.

Primary Common Control Physical Channel (P-CCPCH)


• The SCH is transmitted on the first 256 chips of a timeslot, thus creating here a peak load.

• The cell system information is transmitted in the timeslot except for the first 256 chips. By doing so, a

high interference and load at the beginning of the timeslot is avoided.

• This leads to a net data rate of 27 kbps for the cell system information.

• Channel estimation is done with the CPICH, so that no pilot sequence is required in the P-CCPCH.

• (The use of the pilot sequence is explained in the context of the DPDCH later on in this

document.)

• There are also no power control (TPC) bits transmitted to the UE‘s.

CP



P-CCPCH

10 ms Frame

Primary Common Control Physical Channel (P-CCPCH)


P-CCPCH

Finally, I get the cell system information

• channelisation code: Cch,256,1

• no TPC, no pilot sequence• 27 kbps (due to off period)• organised in MIBs and SIBs

• WCEL: PtxPrimaryCPICH•The parameter determines the transmission power of the primary CPICH channel. •It is used as a reference for all common channels. •[-10 dBm … 50 dBm], step 0.1 dB, default: 33dBm (WPA power = 43 dBm)

• WCEL: PtxPrimarySCH•Transmission power of the primary synchronization channel, the value is relative to primary CPICH transmission power.•[-35 dB … 15 dB], step size 0.1 dB, default: -3 dB

• WCEL: PtxSecSCH•Transmission power of the secondary synchronization channel, the value is relative to

NSN Parameters for Cell Search


•Transmission power of the secondary synchronization channel, the value is relative to primary CPICH transmission power.•[-35 dB… 15 dB], step size 0.1 dB, default: -3 dB

• WCEL: PtxPrimaryCCPCH•This is the transmission power of the primary CCPCH channel, the value is relative to primary CPICH transmission power.•[-35 dB … 15 dB], step size 0.1 dB, default: -5 dB

• WCEL: PriScrCode•Identifies the downlink scrambling code of the Primary CPICH (Common Pilot Channel) of the Cell.•[0 ... 511]

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Synchronisation Issues in UMTS. 5 different UTRAN synchronisation issues were identified:

1. Network synchronisation stands for the very accurate reference frequency, which must be

distributed to the individual UTRAN network elements.

2. Node synchronisation takes place between the Node B and the RNC.

• Node Synchronisation is used to determine the run-time difference between UTRAN nodes,

which must be estimated and then compensated.

• In the FDD mode, only RNC-Node B Node Synchronisation is in use.

3. While radio interface synchronisation is required between the UE and the Node B.

Synchronisation Issues and Node Synchronisation


3. While radio interface synchronisation is required between the UE and the Node B.

4. Transport channel synchronisation is a L2 synchronisation (for the MAC layer).

• It is therefore done between the UE and the RNC.

• Please note in this context, that a UE may be in a soft handover state, i.e. the UE may be

connected to several cells simultaneously.

• Transport channel synchronisation is required to guarantee, that the transport of user data

via several channels is coordinated in such a way, that the transmitted data from several

cells arrives within the UE‘s receive window.

5. Time alignment handling takes place between UTRAN and the CN for adequate timing of data

transfer.

SRNCNode B

3112

3113

3114

RFN128

129

130

BFN

T1

T2

DL offsetBFN: Node B Frame

Number counter0..4095 frames

RFN: RNC Frame

Number counter0..4095 frames

Node Synchronisation


tim

e

3114

3115

3116

3117

3118

tim

e

131

132

133

134

135

(T4)

T2

T3

(T4 – T1) – (T3 – T2)= Round Trip Delay(RTD) determinationfor DCH services

T1, T2, T3range: 0 .. 40959.875 ms

resolution: 0.125 ms

UL offset

user plane defined onDCH, FACH & DSCH

0..4095 frames

• A timing reference is required by the Node Synchronisation:

• Node B Frame Number (BFN)• The BFN is a counter at the Node B, based on the 10 ms framing structure of WCDMA.

• RNC Frame Number (RFN)• The RFN is a counter at the RNC, based on the 10 ms framing structure of WCDMA.

• Cell System Frame Number (SFN)• This is a counter for each cell, and is broadcasted on the P-CCPCH.

• With one Node B, several (sector) cells can be deployed. These cells overlap.

• If the SCH is transmitted at the same time in all the sector cells of the Node B, and when a UE is in

Cell Synchronisation and Sectorised Cells


• If the SCH is transmitted at the same time in all the sector cells of the Node B, and when a UE is in

the overlapping coverage area of two of these cells, it will have difficulties to synchronise to one cell.

• As a consequence, an offset can be used for neighbouring cells of one Node B: T_cell. • T_cell is a timing delay for the starting time of the physical channels SCH, CPICH, BCCH relative

to the Node B‘s timer BFN.

• The timing delay is a multiple (0..9) of 256 chips due to of the length of a SCH burst.

• The cell‘s timing is identified with the counter SFN = BFN + T_cell.

• (Please note, that this description only applied for the FDD mode!)

cell1

cell2

cell3

1 TS

SCH

SCH

SCH

SCH

SCH

SCH

SCH

T_cell

T_cell1

T_cell2SCH

Cell Synchronization and Sectorised Cells


Node B with threesectorised cells

BFN

SFN = BFN + T_cell1

SFN = BFN + T_cell2

SFN = BFN + T_cell3

T_cell3

SFN: Cell System Frame Numberrange: 0..4095 frames

T_cell: n ∗∗∗∗ 256 chips, n = 0..9

cell3 cell2

cell1

• WCEL: Tcell•Timing delay is used for defining the start of SCH, P-CPICH, Primary CCPCH and DL

Scrambling Code(s) in a cell relative to BFN.

•[0 ... 2304] chips, step 256 chips, no default value.

NSN Parameters for Sectorised Cells


Part IVCommon Control Physical Channels


• The S-CCPCH can be used to transmit the transport channels

• Forward Access Channel (FACH) and

• Paging Channel (PCH).

• More than one S-CCPCH can be deployed.

• The FACH and PCH information can multiplexed on one S-CCPCH – even on the same 10 ms frame -

, or they can be carried on different S-CCPCH.

Secondary Common Control Physical Channel (S-CCPCH)


• The first S-CCPCH must have a spreading factor of 256, while the spreading factor of the remaining

S-CCPCHs can range between 256 and 4.

• UTRAN determines, whether a S-CCPCH has the TFCI (Transport Format Combination Indicator)

included.

• Please note, that the UE must support both S-CCPCHs with and without TFCI.

Slot 0 Slot 1 Slot 2 Slot 14

10 ms Frame

TFCI(optional)

Data Pilot bits

Secondary Common Control Physical Channel(S-CCPCH)


S-CCPCH

(optional)Data Pilot bits

• carries PCH and FACH

• Multiplexing of PCH and FACH on one

S-CCPCH, even one frame possible

• with and without TFCI (UTRAN set)

• SF = 4..256

• (18 different slot formats

• no inner loop power control

Secondary CCPCH in NSN RAN

The Secondary CCPCH (Common Control Physical Channel) carries FACH and PCH transport channels

In RAN’04, number of SCCPCHs increase from two to three. The three SCCPCH channel configuration is needed only if SAB – Service area Broadcast is used.

Parameter NbrOfSCCPCHs (Number of SCCPCHs) tells how many SCCPCHs will be configured for the cell. (1, 2 or 3)

• If only one SCCPCH is used in a cell, it will carry FACH-c (Containing DCCH/CCCH /BCCH), FACH-u (containing DTCH) and PCH. FACH and PCH multiplexed onto the same SCCPCH.


same SCCPCH.

• If two SCCPCHs are used in a cell, the first SCCPCH will always carry PCH only and the second SCCPCH will carry FACH-u and FACH-c.

• If three SCCPCHs are used in a cell, the third SCCPCH will carry FACH-s (containing CTCH) and FACH-c idle (containing CCCH and BCCH ) . The third SCCPCH is only

needed when Service Area Broadcast (SAB) is active in a cell.

Logical channel DTCH DCCH CCCH BCCH CTCH PCCH

For SABFor SAB

DL common Channel configuration in case of three SCCPCH



Transport channel

Physical channel

FACH-u PCHFACH-s

SCCPCH connected

SCCPCH idle

FACH-c FACH-c

SCCPCH page

SF 64 SF 128 SF 256

FACH-u FACH-c(connected)

FACH-c(idle)

TFS

0: 0x360 bits(0 kbit/s)


1: 1x168 bits


1: 1x168 bits (16.8 kbit/s)

2: 2x168 bits(33.6 kbit/s)


1: 1x168 bits(16.8 kbit/s)

FACH-s


1: 1x168 bits(16.8 kbit/s)

PCH





TTI

Channelcoding

CRC

10 ms

TC 1/3

16 bit

(33.6 kbit/s)

10 ms

CC 1/2

16 bit

10 ms

CC 1/3

16 bit

10 ms

CC 1/3

16 bit

10 ms

CC 1/2

16 bit

FACH-u PCHFACH-s

SCCPCH connected

SCCPCH idle

FACH-c FACH-c

SCCPCH page

TFCSTFCS TFCS



TFCS01

0 kbit/s8 kbit/s

TFCS00010210

0+0 = 0 kbit/s0+16.8 = 16.8 kbit/s0+33.6 = 33.6 kbit/s

36+0 = 36 kbit/s

TFCS001001

0+0 = 0 kbit/s16.8+0 = 16.8 kbit/s0+16.8 = 16.8 kbit/s

Maximum transport channel throughput = 36

kbit/s

Maximum transport channel

throughput = 8 kbit/s

Maximum transport channel throughput = 16.8

kbit/s

• The network has detected, that there is data to be transmitted to the UE.

• Both in the RRC idle mode and in the RRC connected mode (e.g. in the sub-state CELL_PCH) a UE

may get paged. But how does the mobile know, when it was paged?

• And in order to save battery power, we don‘t want the UE to listen permanently to paging

channel – instead, we want to have discontinuous reception (DRX) of paging messages.

• But when and where does the UE listen to the paging messages?

• Cell system information is broadcasted via the P-CCPCH.

• The cell system information is organised in System Information Blocks (SIB).

• SIB5 informs the mobile phones about the common channel configuration, including a list of

S-CCPCH descriptions.

• The first 1 to K entries transmit the (transport channel) PCH, while the remaining S-CCPCH

S-CCPCH and the Paging Process


• The first 1 to K entries transmit the (transport channel) PCH, while the remaining S-CCPCH

in the list hold no paging information.

• The UE determines the S-CCPCH, where it is paged, by its IMSI and the number of PCH/S-CCPCHs

carrying S-CCPCHs K.

• When paging the UE, the RNC knows the UE‘s IMSI, too, so that it can put the paging message on

the correct PCH transport channel.

• Discontinuous Reception (DRX) of paging messages is supported.

• A DRX cycle length k has to be set in the network planning process for the cs domain, ps

domain, and UTRAN.

• k ranges between 3 and 9. If for instance k=6, then the UE is paged every 2k = 640 ms.

• If the UE is in the idle mode, it takes the smaller k-value of either the cs- or ps-domain.

• If the UE is in the connected mode, it has to select the smallest k-value of UTRAN and the

CN, it is not connected to.

Node B

UTRANP-CCPCH/BCCH (SIB 5)

commonchannel

definition,including

a lists ofUE

Index of S-CCPCHs

RNC

S-CCPCH and the Paging Process


S-CCPCH carrying one PCH



S-CCPCH without PCH

S-CCPCH without PCH

0

1

K-1

UE‘s paging channel:

Index = IMSI mod K

e.g. if IMSI mod K = 1

„my pagingchannel“

2k framesk = 3..9

Duration:

CN domain specificDRX cycle lengths

(option)

CS Domain PS Domain UTRAN

RRC connectedmode

Example withtwo CN domains

Paging and Discontinuous Reception (FDD mode)


UEUpdate:a) derived by NAS

negotiationb) otherwise:

system info

Update:locally with

system info

k1 k2

Update:a) derived by NAS

negotiationb) otherwise:

system info

k3stores

if RRC idle:UE DRX cycle length is

min (k1, k2)

if RRC connected:UE DRX cycle length is

min (k3, kdomain with no Iu-signalling connection)

• Paging Indicator Channel (PICH)• UMTS provides the terminals with an efficient sleep mode operation. The UEs do not have to read and

process the content, transmitted during their paging occasion on their S-CCPCH.

• Each S-CCPCH, which is used for paging, has an associated Paging Indicator Channel (PICH).

• A PICH is a physical channel, which carries paging indicators.

• A set of (paging indicator) bits within the PICH indicate to a UE, whether there is a paging occasion for

it. Only then, the UE listens to the S-CCPCH frame, which is transmitted 7680 chips after the PICH

frame in order to see, whether there is indeed a paging message for it.

• The PICH is used with spreading factor 256.

• 300 bits are transmitted in a 10 ms frame, and 288 of them are used for paging indication.

• The UE was informed by the BCCH, how many paging indicators exist on a 10 ms frame.

The Paging Process


• The UE was informed by the BCCH, how many paging indicators exist on a 10 ms frame.

• The number of paging indicator Np can be 18, 36, 72, and 144, and is set by the operator as part

of the network planning process.

• The higher Np, the more paging indicators exist, the more paging groups exist, among which UEs

can be distributed on.

• Consequently, the lower the probability, that a UE reacts on a paging indicator, while there is no

paging message in the associated S-CCPCH frame.

• But a high number of paging indicators results in a comparatively high output power for the PICH,

because less bits exists within a paging indicator to indicate the paging event.

• The operator then also has to consider, if he has to increase the number of paging attempts.

• How does the UE and UTRAN determine the paging indicator (PI) and the Paging Occasion?

• This is shown in one of the next slides.

PICH frame

S-CCPCH frame, associated with PICH frame

ττττPICH

= 7680chips

for paging indication no transmission

ττττS-CCPCH

S-CCPCH and its associated PICH


b287 b288 b299b286b0 b1

for paging indication no transmission

# of pagingindicators per frame

(Np)

18

36

72

144

UE

my pagingindicator (PI)

PI = ( IMSI div 8192) mod Np

DRX index

number of paging indicators18, 36, 72, 144

Paging Indicator and Paging Occasion (FDD mode)


Paging Occasion = (IMSI div K) mod (DRX cycle length) + n * DRX cycle length

UE

When willI get paged? number of S-CCPCH with PCH

FDDmode

Example – Paging instant and group calculation

UE calculates paging instant based on following information as presented before

• IMSI

• Number of S-CCPCH (K)

• DRX cycle length (k)

• Np

User are distributed to different paging groups based on their IMSI. Paging group


User are distributed to different paging groups based on their IMSI. Paging group size can be calculated based on

• Number of S-CCPCH (K)

• DRX cycle length (k)

• Np

Paging group size affects on how often UE has to decode paging message from S-CCPCH � Power consumption

Example – Paging instant and group calculation

K (Number of S-CCPCH with PCH) 1

k (DRX length) 6

DRX cycle length 64 frames

IMSI 358506452377

Which S-CCPCH #? 0

IMSI div K 358506452377

When (Paging occation, SFN)? 25 + n*DRX cycle length

Np 72 PIs/frame


Np 72 PIs/frame

DRX Index 43762994

My PI? 26

Number of subsc. In LA/RA 100000

Number of subsc. Per S-CCPCH 100000

Number of subsc. Paging occation (PICH

frame) 1562.5

Number of subsc. Per PI 21.7

• WCEL: NbrOfSCCPCHs•The parameter defines how many S-CCPCH are configured for the given cell.

•Range: [1 … 3], step: 1; default = 1

• WCEL: PtxSCCPCH1 (carries FACH & PCH)

•This is the transmission power of the 1st S-CCPCH channel, the value is relative to primary

CPICH transmission power.

•Range: [-35 dB … 15 dB] , step size 0.1 dB, default: 0 dB

• WCEL: PtxSCCPCH2 (carries PCH only)

NSN Parameters for S-CCPCH and Paging


• WCEL: PtxSCCPCH2 (carries PCH only)

•This is the transmission power of the 2nd S-CCPCH channel, the value is relative to primary

CPICH transmission power.

•Range: [-35 dB … 15 dB] , step size 0.1 dB, default: - 5 dB

• WCEL: PtxSCCPCH3 (carries FACH only)

•This is the transmission power of the SCCPCH channel which carries only a FACH

(containing CCCH) and a FACH (containing CTCH).

•This parameter is only needed when Service Area Broadcast(SAB)is activated in a cell(three

S-CCPCH channel configuration).

•Range: [-35 dB … 15 dB] , step size 0.1 dB, default: - 2 dB

• WCEL: PtxPICH•This is the transmission power of the PICH channel.

•It carries the paging indicators which tell the UE to read the paging message from the

associated secondary CCPCH.

•This parameter is part of SIB 5.

•[-10 dB..5 dB]; step 1 dB; default: -8 dB (with Np =72)

•NP•Repetition of PICH bits

•[18, 36, 72, 144] with relative power [-10, -10, -8, -5] dB

NSN Parameters for S-CCPCH and Paging


• RNC: CNDRXLength•The DRX cycle length used for CN domain to count paging occasions for discontinuous

reception.

•This parameter is given for CS domain and PS domain separately.

•This parameter is part of SIB 1.

•[640, 1280, 2560, 5120] ms; default = 640 ms.

• WCEL: UTRAN_DRX_length•The DRX cycle length used by UTRAN to count paging occasions for discontinuous

reception.

•[80, 160, 320, 640, 1280, 2560, 5120] ms; default = 320 ms

• The transport channel Forward Access Channel (FACH) is used, when relatively small amounts of

data have to be transmitted from the network to the UE.

• The FACH is only transmitted downlink.

• In-band signalling is used to indicate, which UE is the recipient of the transmitted data (see MAC PDU

with UE-ID type).

• This common downlink channel is used without (fast) closed loop power control and is available all

over the cell.

FACH and S-CCPCH


• FACH data is transmitted in one or several S-CCPCHs.

• FACH and PCH data can be multiplexed on one S-CCPCH, but they can also be be transmitted on

different S-CCPCHs.

• The FACH is organised in FACH Data Frames via the Iub-interface.

• Each FACH Data Frames holds the Transmission Blocks for one TFS.

• The used TFS is identified by the TFI.

• A TFI is associated with one Transmission Time Interval (TTI), which can be either 10, 20, 40 or 80

ms.

• The TTI identifies the interleaving time on the radio interface.

• FACH Data Frame has header fields, which identify the CFN, TFI, and the Transmit Power Level.

• The Transmit Power Level gives the preferred transmission power level for the FACH and for the TTI

time.

• The values specified here range between 0 and 25.5 dB, with a step size of 0.1 dB.

• The value is taken as a negative offset to the maximum power configured for the S-CCPCHs,

specified for the FACH.

• The pilot bits and the TFCI-field may have a relative power offset to the power of the data field, which

may vary in time.

• (The offset is determined by the network.)

• The power offsets are set by the NBAP message COMMON TRANSPORT CHANNEL SETUP

REQUEST, which is sent from the RNC to the Node B.

FACH and S-CCPCH


REQUEST, which is sent from the RNC to the Node B.

• There are two power offset information included:

• PO1: defines the power offset for the TFCI bits; it ranges between 0 and 6 dB with a 0.25 step

size.

• PO3: defines the power offset for the pilot bits; it ranges between 0 and 6 dB with a 0.25 step

size.

• Another important parameter is the maximum allowed power on the FACH: MAX FACH Power.

Blank Page


Node B RNC

FACH Data Frame

CFN TFI TB TB

Iub

Uu

Transmit Power Level

Power offsets for TFCI and pilot bits are

defined during channel setup

FACH and S-CCPCH


Transmit Power Level

UE

TFCI(optional)

Data

Pilot bits

max. transmitpower for S-CCPCH

0..25.5 dB,step size 0.1

PO1 PO3

• WCEL: PowerOffsetSCCPCHTFCI•Defines the power offset for the TFCI symbols relative to the downlink transmission power of a Secondary CCPCH.•This parameter is part of SIB 5.

•P01_15/30/60•15 kbps: [0..6 dB]; step 0.25 dB; default: 2 dB•30 kbps: [0..6 dB]; step 0.25 dB; default: 3 dB•60 kbps: [0..6 dB]; step 0.25 dB; default: 4 dB

NSN Parameters for S-CCPCH Power Setting


Part VPhysical Random Access


• In the random access, initiated by the UE, two physical channels are involved:

• Physical Random Access Channel (PRACH)• The physical random access is decomposed into the transmission of preambles in the

uplink.

• Each preamble is transmitted with a higher output power as the preceding one.

• After the transmission of a preamble, the UE waits for a response by the Node B.

• This response is sent with the physical channel Acquisition Indication Channel (AICH),telling the UE, that the Node B as acquired the preamble transmission of the random access.

• Thereafter, the UE sends the message itself, which is the RACH/CCCH of the higher layers.

• The preambles are used to allow the UE to start the access with a very low output power.

Random Access


• The preambles are used to allow the UE to start the access with a very low output power.

• If it had started with a too high transmission output power, it would have caused

interference to the ongoing transmissions in the serving and neighbouring cells.

• Please note, that the PRACH is not only used to establish a signalling connection to

UTRAN, it can be also used to transmit very small amounts of user data.

• Acquisition Indication Channel (AICH)• This physical channel indicates to the UE, that it has received the PRACH preamble and is

now waiting for the PRACH message part.

Node BUENo response

by theNode B

No responseby theNode B

Random Access – the Working Principle


Node B

I just detecteda PRACH preamble

OLA!

• The properties of the PRACH are broadcasted (SIB5, SIB6).

• The candidate PRACH is randomly selected (if there are several PRACH advertised in the cell) as well

as the access slots within the PRACH.

• 15 access slots are given in a PRACH, each access slot lasting two timeslots or 5120 chips.

• In other words, the access slots stretch over two 10 ms frames.

• A PRACH preamble, which is transmitted in an access slot, has a length of 4096 chips.

• Also the AICH is organised in (AICH) access slots, which stretch over two timeslots.

• AICH access slots are time aligned with the P-CCPCH.

• The UE sends one preamble in uplink access slot n.

• It expects to receive a response from the Node B in the downlink (AICH) access slot n, ττττ chips later

Random Access Timing


• It expects to receive a response from the Node B in the downlink (AICH) access slot n, ττττp-a chips later

on.

• If there is no response, the UE sends the next preamble ττττp-p chips after the first one.

• The maximum numbers of preambles in one preamble access attempt can be set between 1 and 64.

• The number of PRACH preamble cycles can be set between 1 and 32.

• If the AICH_Transmission_Timing parameter in the SIB is set to BCCH SIB5 & SIB6 to

• 0 = then, the minimum preamble-to-preamble distance is 3 access slots, the minimum

preamble-to-message distance is 3 access slots, and the preamble-to-acquisition indication

is 3 timeslots.

• 1 = then, the minimum preamble-to-preamble distance is 4 access slots, the minimum

preamble-to-message distance is 4 access slots, and the preamble-to-acquisition indication

is 5 timeslots.

SFN mod 2 = 0 SFN mod 2 = 0SFN mod 2 = 1

P-CCPCH

AICH accessslots 0 1 1282 1175 964 13103 14 0 1 2 75 643

5120chips

UE point of view

Acquisition

(distances depend on AICH_Transmission_Timing )

Random Access Timing


Preamble

5120 chips

Preamble

AS # i

4096 chips

preamble-to-preamble

distance ττττp-p

PRACHaccess slots

AICHaccess slots

Messagepart

preamble-to-message

distance ττττp-m

AcquisitionIndication

preamble-to-AI

distance ττττp-a

AS # i

• RACH Sub-channels• RACH sub-channels were introduced to define a sub-set of uplink access slots.

• A total number of 12 RACH sub-channels exist, numbered from 0 to 11.

• The PRACH access slots are numbered relative to the AICH assess slot.

• The offset is given by ττττp-a (see preceding slides).

• The AICH is transmitted synchronised to the P-CCPCH.

• An access slot of sub-channel #i is using access slot #i, when SFN mod 8 = 0 or 1. It is then

using every 12th access slot following access slot #i.

• You can see in the figure on the right hand side all existing sub-channels and the timeslots,

they are using.

• Access Classes (AS) and Access Service Classes (ASC)

RACH Sub-channels and Access Service Classes


• Access Classes (AS) and Access Service Classes (ASC)• Access Service Classes were introduced to allow priority access to the PRACH resources,

by associating ASCs to specific access slot spaces (RACH sub-channels) and signatures.

• 8 ASC can be specified by the operator; The UE determines the ASC and its associated

resources from SIB5 and SIB7.

• The mapping of the subscribers access classes (1..15) is part of the SIB5 cell system

information.

• RACH Access Slot Sets• Two access slot set were specified:

• Access slot set 1 holds PRACH access slots 1 to 7, i.e. the PRACH access slots, whose

corresponding AICH access slots begin in a P-CCPCH with a SFN modulo 2 = 0.

• Access slot set 2 holds PRACH access slots 8 to 15, i.e. the PRACH access slots, whose

corresponding AICH access slots begin in a P-CCPCH with a SFN modulo 2 = 1.

SFN mod 8 of the

corresponding

P-CCPCH frame

0

1

2

3

4

0

12

9

6

1

13

10

7

2

14

11

3

0

12

4

1

13

5

2

14

6

3

0

7

4

1

8

5

2

9

6

3

10

7

4

Sub-channel number

1 2 3 4 5 6 7 8 9 10 11

11

8

5

0

PRACH Sub-channels and Access Service Classes (ASC)


4

5

6

7

6

3

7

4

8

5

9

6

10

7

11

8

0

12

9

1

13

10

2

14

11

3

0

12

4

1

13

5

2

14

(cited from TS 25.214 V5.11.0, chap. 6.1.1)

Node B

BCCH (SIB 5, SIB 7)

UE• ASCs and their PRACH access resources + signatures,• AC mapping into ASCs

• In the PRACH preamble, a random preamble code is used.

• This code is composed from a

• Preamble Scrambling Code and a

• Preamble Signature

• There is a total of 16 preamble signatures of 16 bit length, which is repeated 256 times within one

preamble.

• When monitoring the cell system information, the UE gets the information, which of the signatures are

available for use in the cell. (see IE PRACH info)

• There are 8192 preamble scrambling codes, which are constructed from the long scrambling code

PRACH Preamble


• There are 8192 preamble scrambling codes, which are constructed from the long scrambling code

sequences.

• The PRACH preamble scrambling codes are organised in 512 groups, with each group holding 16

members.

• There are also 512 primary scrambling codes available in UMTS, and one of them is in use in the cell.

• If the primary scrambling code s is in use in the cell, then only the PRACH preamble scrambling codes

belonging to PRACH preamble scrambling code group s can be used for random access.

• Consequently, 16 PRACH preamble scrambling codes are left, and the BCCH is used to inform the

UE, which PRACH preamble scrambling codes can be used. (see IE PRACH info)

Node B

UTRANBCCH

UE RNC• available signatures for

random access• available preamble

scrambling codes• available spreading

factor• available sub-channels• etc.

PRACH Preamble


Pi Pi Pi Pi

Preamble Signature

(16 different versions)

16 chip

256 repetitions

⊗

PRACH Preamble Scrambling Code

• 512 groups à 16 preamble scrambling codes

• Cell‘s primary scrambling codes associated with preamble scrambling code group

• etc.

• The length of the PRACH message part can be 10 ms or 20 ms.

• Its length is set as Transmission Time Interval (TTI) value by the higher layers.

• Uplink, we apply code multiplexing.

• Control data (L1 data) is transmitted with spreading factor 256, while message data can be

transmitted with spreading factors 256, 128, 64 or 32.

• The message data contains the information, given by the RACH.

• The control data contains 8 known pilot bits per timeslot. 15 different pilot bit sequences exist – they

are associated with the timeslot, where the transmission takes place within the 10 ms message frame.

2 bits in the control data carry TFCI bits per timeslot.

• Which spreading code is allocated to the message part?

PRACH Message Part


• Which spreading code is allocated to the message part?

• The message part‘s channelisation code is determined from the signature, which was used by the UE

in the preamble.

• 16 different signatures exist, and each can be correlated to a channelisation code in the

channelisation code tree with spreading factor 16.

• The channelisation codes are calculated like this:

• Each signature has a number k, with 0 ≤ k ≤ 15.

• For the control data, the channelisation code CCH,256,n is used, with n = 16*k + 15.

• For the message data, the channelisation code CCH,SF,m is used, with m = SF*k/16.

• The scrambling code is the same, which was used for the PRACH preamble.


10 ms Frame

RACH data

L1 control data 8 Pilot bits (sequence depends on slot number) 2 TFCI bits

data

PRACH Message Part


• SF = 256• channelisation code:

CCH,256,16*k+15, withk = signature number

• SF = 256, 128, 64, or 32• channelisation code:

• CCH,SF,SF*k/16, with

k = signature number

Scrambling code =

PRACH preamble scrambling code

• When it comes to the random access, two questions have to be asked:

• What kind of output power does the UE select for the first preamble?

• And how does the output power change with the subsequent preambles and the message part?

• Open Loop Power Control• The output power for the first PRACH preamble is based in parts on broadcasted parameters (SIB6, if

missing, from SIB5; and SIB7).

• The UE acquires the Node B‘s “Primary CPICH TX Power“, a “Constant Value“, and the “UL

Interference“ level.

• The UE also determines the received CPICH RSCP (variable CPICH_RSCP).

• Then, it calculates the power for the first preamble:

PRACH Power Setting


• Then, it calculates the power for the first preamble:

• Preamble_Initial_Power = Primary CPICH TX power – CPICH_RSCP + UL interference + Required received C/I

• The “Required received C/I“ is an UTRAN parameter (NSN: PRACHRequiredReceivedCI;

range: -35 ... -10 dB, step 1 dB default: -25dB).

• The “UL Interference“ is measured by the Node B and broadcasted via SIB 7 on P-CCPCH

to the UEs.

• The power ramp steps from one preamble to the next can be set between 1 and 8 dB (step size 1dB).

• The power offset between the last PRACH and the PRACH control message can be set between –5

and 10 dB (step size 1dB).

• The gain factor ßc is used for the PRACH control part.

Preamble_Initial_Power =Primary CPICH TX power– CPICH_RSCP+ UL interference + Required received C/I*

UL interference

1st preamble: power setting

attenuation in the DL

estimated receive levelConstant Value

PRACH Power Setting

*NSN: PRACHRequiredReceivedCI


at Node B

Pre-amble

Controlpart

Pre-amble

Pre-amble

Pp-p

Pp-p

Pp-m

1..8 dB-5..10 dB

# of preambles: 1..64 # of preamble cycles: 1..32

• The AICH is used to indicate to UEs, that their PRACH preamble was received, and that the Node B is

expecting to receive the PRACH message part next.

• The AICH returns an indicator of signature s, which was used in the PRACH preamble.

• Spreading factor is fixed to 256 for the AICH.

• The AICH is transmitted via 15 access slots, each lasting 5120 chips.

• Consequently, the AICH access slots are distributed over two consecutive 10 ms frames.

• Similar to the PRACH preamble, only 4096 chips are used to transmit the Acquisition Indicator part.

• 32 real value symbols are transmitted.

• Each real value is calculated by a sum of AIsbs,j.

• AI is an acquisition indicator for signature s.

• If signature s is positively confirmed, Ai is set to +1; a negative confirmation results in –1; if

Acquisition Indication Channel (AICH)


• If signature s is positively confirmed, Ais is set to +1; a negative confirmation results in –1; if

signature s is not part of the active signature set, then Ais is set to 0. bs,j stands for signature

pattern j, with j = 0..31.

• If more than one PRACH preamble signatures within one PRACH access slot is detected correctly,

the Node B sends the AIs of all the detected signatures simultaneously in the 1st or 2nd AICH

access slot after the PRACH access slot.

• If the number of correctly detected signatures is higher than the Node B's capability to

simultaneously decode the PRACH message parts, a negative AIs is used for generating the AIs

for those PRACH messages, which can not be decoded within the default message part

transmission timing.

• A negative AI indicates to the MS that it shall exit the random access procedure.• The Node B 's capability to decode the PRACH message parts is determined in the RNC and

transmitted to the Node B.

Access Slot 0 Access Slot 1 Access Slot 2 Access Slot 14

20 ms Frame

a0 a1 a2 a29 a30 a31

Acquisition Indication Channel (AICH)


∑=

=15

0

js,sj bAIas

AICH signature pattern (fixed)

Acquisition Indicator

• +1 if signature s is positively confirmed

• -1 if signature s is negatively confirmed

• 0 if signature s is not included in the

set of available signatures

• In RAN1, Node B L1 shall be able to simultaneously scan 12 RACH sub-channels with 4 signatures

per sub-channel from UEs situating up to 'Cell radius' distance from the Node B site.

• 'Cell radius' is the maximum radius of the cell and it is given from the RNC to the Node B. In RAN1,

the maximum value for the 'Cell radius' is 20 km.

• WCEL: PRACHRequiredReceivedCI• This UL required received C/I value is used by the UE to calculate the initial output power on

PRACH according to the Open loop power control procedure.• This parameter is part of SIB 5.• [-35 dB..-10 dB]; step 1 dB; default -25 dB

• WCEL: PowerRampStepPRACHPreamble• UE increases the preamble transmission power when no acquisition indicator is received by UE in

NSN Parameters Related to the PRACH and AICH


• UE increases the preamble transmission power when no acquisition indicator is received by UE in AICH channel.

• This parameter is part of SIB 5.• [1dB..8dB]; step 1 dB; default: 2 dB

• WCEL: PowerOffsetLastPreamblePrachMessage• The power offset between the last transmitted preamble and the control part of the PRACH

message.• [-5 dB..10 dB]; step 1 dB; default 2dB

• WCEL: PRACH_preamble_retrans• The maximum number of preambles allowed in one preamble ramping cycle, which is part of

SIB5/6.• [1 ... 64]; step 1; default 8.

• WCEL: RACH_tx_Max• Maximum number of RACH preamble cycles defines how many times the PRACH pre-amble

ramping procedure can be repeated before UE MAC reports a failure on RACH transmission to higher layers.

• This message is part of SIB5/6.• [1 ... 32]; default 8.

• WCEL: PRACHScramblingCode• The scrambling code for the preamble part and the message part of a PRACH Channel, which is

part of SIB5/6.• [0 ... 15]; default 0.



• WCEL: AllowedPreambleSignatures• The preamble part in a PRACH channel carries one of 16 different orthogonal complex signatures.

NSN Node B restrictions: A maximum of four signatures can be allowed (16 bit field).• [0 ... 61440]; default 15.

• WCEL: AllowedRACHSubChannels• A RACH sub-channel defines a sub-set of the total set of access slots (12 bit field).• [0 ... 4095]; default 4095.

• WCEL: PtxAICH• This is the transmission power of one Acquisition Indicator (AI) compared to CPICH power. • This parameter is part of SIB 5.• [-22 ... 5] dB, step 1 dB; default: -8 dB.

• WCEL: AICHTraTime• AICH transmission timing defines the delay between the reception of a PRACH access slot

including a correctly detected preamble and the transmission of the Acquisition Indicator in the AICH.

• 0 ( Delay is 0 AS), 1 ( Delay is 1 AS) ;default 0.

• WCEL: RACH_Tx_NB01min



• WCEL: RACH_Tx_NB01min• In case that a negative acknowledgement has been received by UE on AICH a backoff timer TBO1

is started to determine when the next RACH transmission attempt will be started.• The backoff timer TBO1 is set to an integer number NBO1 of 10 ms time intervals, randomly

drawn within an Interval 0 ≤ NB01min ≤ NBO1 ≤ NB01max (with uniform distribution).• [0 ... 50]; default: 0.

• WCEL: RACH_Tx_NB01max• [0 ... 50]; default: 50.

Summary of RACH procedure

1- Decode from BCCH

• Available RACH spreading factors

• RACH scrambling code number

• UE Access Service Class (ASC) info

• Signatures and sub-channels for each ASC

• Power step, RACH C/I requirement = “Constant”, BS interference level

2 – Calculate initial preamble power

3 – Calculate available access slots in the next full access slot set and select randomly one of those

(Adopted from TS 25.214)


of those

4 – Select randomly one of the available signatures

5 – Transmit preamble in the selected access slot with selected signature

6 – Monitor AICH

• IF no AICH– Increase the preamble power

– Select next available access slot & Go to 3

• IF negative AICH or max. number of preambles exceeded– Exit RACH procedure

• IF positive AICH

– Transmit RACH message with same scrambling code and channelisation code related to signature

Part VIDedicated Physical Channel Downlink


• The downlink DPCH is used to transmit the DCH data.

• Control information and user data are time multiplexed.

• The control data is associated with the Dedicated Physical Control Channel (DPCCH), while the user

data is associated with the Dedicated Physical Data Channel (DPDCH).

• The transmission is organised in 10 ms radio frames, which are divided into 15 timeslots.

• The timeslot length is 2560 chips. Within each timeslot, following fields can be found:

• Data field 1 and data field 2, which carry DPDCH information

• Transmission Power Control (TPC) bit field

• Transport Format Combination Indicator (TFCI) field, which is optional

• Pilot bits

• The exact length of the fields depends on the slot format, which is determined by higher layers.

Downlink Dedicated Physical Channel (DPCH)


• The exact length of the fields depends on the slot format, which is determined by higher layers.

• The TFCI is optional, because it is not required for services with fixed data rates.

• Slot format are also defined for the compressed mode; hereby different slot formats are in used, when

compression is achieved by a changed spreading factor or a changed puncturing scheme.

• The pilot sequence is used for channel estimation as well as for the SIR ratio determination within the

inner loop power control.

• The number of the pilot bits can be 2, 4, 8 and 16 – it is adjusted with the spreading factor.

• A similar adjustment is done for the TPC value; its bit numbers range between 2, 4 and 8.

• The spreading factor for a DPCH can range between 4 and 512. The spreading factor can be changed

every TTI period.

• Superframes last 720 ms and were introduced for GSM-UMTS handover support.


10 ms Frame

Radio Frame0

Radio Frame1

Radio Frame2

Radio Frame71

Superframe = 720 ms




TPCbits

Pilot bitsTFCIbits

(optional)

Data 2 bitsData 1 bits

DPDCHDPDCH DPCCH DPCCH

• 17 different slot formats• Compressed mode slot

format for changed SF & changed puncturing

• Following features are supported in the downlink:

• Blind rate detection, and

• Discontinuous transmission.

• Rate matching is done to the maximum bit rate of the connection. Lower bit rates are possible,

including the option of discontinuous transmission.

• Please note, that audible interference imposes no problem in the downlink.

• Multicode usage:• Several physical channels can be allocated in the downlink to one UE.

• This can occur, when several DPCH are combined in one CCTrCH in the PHY layer, and the data

rate of the CCTrCH exceeds the maximum data rates allowed for the physical channels.



rate of the CCTrCH exceeds the maximum data rates allowed for the physical channels.

• Then, on all downlink DPCHs, the same spreading factor is used.

• Also the downlink transmission of the DPCHs takes place synchronous.

• One DPCH carries DPDCH and DPCCH information, while on the remaining DPCHs, no DPCCH

information is transmitted.

• But also in the case, when several DPCHs with different spreading factors are in use, the first DPCH

carries the DPCCH information, while in the remaining DPCHs, this information is omitted

(discontinuous transmission).

TS TS

maximum bit rate

TS TS TS

discontinuous transmission with lower bit rate

Multicode usage:


DPCCH


TS TS TS

TS TS TS

DPCH 1

DPCH 2

DPCH 3

• Power offsets for the optional TFCI, TPC and pilot bits have to be specified during the radio link setup.

• This is done with the NBAP message RADIO LINK SETUP REQUEST message, where following

parameters are set:

• PO1: defines the power offset for the TFCI bits; it ranges between 0 and 6 dB with a 0.25

step size.

• PO2: defines the power offset for the TPC bits; it ranges between 0 and 6 dB with a 0.25

step size.

• PO3: defines the power offset for the pilot bits; it ranges between 0 and 6 dB with a 0.25

step size.

Power Offsets for the DPCH


step size.

• In the same message, the TFCS, DL DPCH slot format, multiplexing position, FDD TPC DL

step size increase, etc. are defined.

• The FDD TPC DL step size is used for the DL inner loop power control.

DCH Data Frame

Iub

NBAP: RADIO LINK SETUP REQUEST

• Power offsets• TFCS• DL DPCH slot format• FDD DL TPC step

size• ...

Power Offsets for the DPCH


Node B RNC

Iub

UE

Uu

PO1TPCbits

Pilot bitsTFCIbits

(optional) Data 2 bitsData 1 bits

PO3PO2

P0x: 0..6 dBstep size: 0.25 dB

• Inner loop power control is also often called (fast) closed loop power control.

• It takes place between the UE and the Node B.

• We talk about UL inner loop power control, when the Node B returns immediately after the reception of

a UE‘s signal a power control command to the UE. By doing so, the UE‘s SIR ratio is kept at a certain

level (the details will be discussed later on in the course).

• DL inner loop power control control is more complex. When the UE receives the transmission of the

Node B, the UE returns immediately a transmission power control command to the Node B, telling the

Node B either to increase or decrease its output power for the UE‘s DPCH.

• The Node B‘s transmission power can be changed by 0.5, 1, 1.5 or 2 dB. 1 dB must be supported by

the equipment. If other step sizes are supported or selected, depends on manufacturer or operator.

• The transmission output power for a DPCH has to be balanced for the PICH, which adds to the power

Downlink Inner Loop Power Control


• The transmission output power for a DPCH has to be balanced for the PICH, which adds to the power

step size.

• There are two downlink inner loop power control modes:

• DPC_MODE = 0: Each timeslot, a unique TPC command is send uplink.

• DPC_MODE = 1: Three consecutive timeslots, the same TPC command is transmitted.

• One reason for the UE to request a higher output power is given, when the QoS target has not been

met.

• It requests the Node B to transmit with a higher output power, hoping to increase the quality

of the connection due to an increased SIR at the UE‘s receiver.

• But this also increases the interference level for other phones in the cell and neighbouring

cells.

• The operator can decide, whether to set the parameter Limited Power Increase Used.

• If used, the operator can limit the output power raise within a time period.

two modescell

TPC



DPC_MODE = 0

unique TPC commandper TS

DPC_MODE = 1

same TPC over 3 TS,then new command

TPCest per1 TS / 3 TS

UTRAN behaviour

P(k) = P(k - 1) + PTPC(k) + Pbal(k),

currentDL power

poweradjustment

newDL power

Correction termfor RL balancing

toward CPICH

P

PTPCPbal

IF



time

IFLimited Power Increase Used = 'Not used'

PTPC(k) =

+ ∆∆∆∆ TPC, if TPCest (k) = 1

- ∆∆∆∆ TPC, if TPCest (k) = 0

∆∆∆∆ TPC step size: 0.5, 1, 1.5 or 2 dB

mandatory

UTRAN behaviour

P(k) = P(k - 1) + PTPC(k) + Pbal(k),

currentDL power

poweradjustment

newDL power

Correction termfor RL balancing

toward CPICH

P

time

PTPCPbal

IF



IFLimited Power Increase Used = 'used'

DL_Power_Averaging_Window_Size

PTPC

Power_Raise_Limit

K-1

TPCest (k) = 1 => PTPC(k) = 0

otherwise assee preceding

slide

K time

• The P-CCPCH is the timing reference for all physical channels.

• As can be seen in the figure on the right hand side, following timing relationships exist:

• The SCH, CPICH, P-CCPCH and DSCH have an identical timing.

• S-CCPCHs can be transmitted with a timing offset ττττS-CCPCH,n. (n stands for the nth S-CCPCH.)

• The timing offset may be different for each S-CCPCH, but it is always a multiple of 256 chips,

i.e. ττττS-CCPCH,n = Tn * 256 chips, with Tn ∈ {0,..,149}.

• We have already seen, that some S-CCPCHs transmit paging information.

• The associated PICH frame ends ττττPICH = 7680 chips before the associated S-CCPCH frame.

• DPCHs are also transmitted with a timing offset, which may be different for different DPCHs.

• The timing offset ττττ is – similar to the S-CCPCH – a multiple of 256, i.e.

Timing Relationship between Physical Channels


• The timing offset ττττDPCH,k is – similar to the S-CCPCH – a multiple of 256, i.e.

ττττDPCH,k = Tk * 256 chips, with Tk ∈ {0,..,149}.

• The timing of a DSCH, which is allociated with a DPCH, is explained later on in the course

documentation.

• AICH access slots for the RACH and CPCH also require a time organisation.

• As we have seen e.g. with the RACH, an access slot combines two timeslots.

• How can the timing to the P-CCPCH be identified?

• The P-CCPCH transmits the cell system frame number (SFN), which increases by one with

each radio frame.

• The AICH access slot number 0 starts simultaneously with the P-CCPCH frame, whose SFN

modulo 2 is zero.

SFN mod 2 = 0 SFN mod 2 = 1

P-CCPCH

AICH accessslots 0 1 1282 1175 964 13103 14 0

SCH

Timing Relationship between Physical Channels


nth S-CCPCHττττS-CCPCH,n

kth S-DPCHττττDPCH,k

0..38144

(step size 256)

0..38144

(step size 256)

• A major problem arises, when the UE is connected to several cells simultaneously.

• The active set cells must transmit the downlink DPCH in a way that their arrival time is within a receive

window at the UE.

• DLnom is the nominal receive time of a radio frame with a specific CFN at the UE.

• To = 4 TS later, the UE starts to transmit the a radio frame with the same CFN.

• To is always calculated relative to the UE transmission start point.

• Of course, due to multipath propagation and handover situations, the reception of the

beginning of a downlink radio frame is often not exactly at To times before the UE starts to

send.

• When the UE is in a soft handover, and moving from one cell to another, the radio frames arriving from

one cell may arrive later and later, while the radio frames of another cell arrive earlier. I.e., the

Radio Interface Synchronisation


one cell may arrive later and later, while the radio frames of another cell arrive earlier. I.e., the

reception from the two neighbouring cells drifts apart.

• The picture on the right hand side is only valid, if the UE is in the macro-diversity state. In this case,

the parameter Tm is the time difference between the nominal downlink received signal DLnom and the

appearance of the first P-CCPCH of the neighbouring cell.

• The serving RNC determines the required offset between P-CCPCH of the neighbouring cell and the

DL DPCH.

• This information is sent as Frame Offset and Chip Offset to the target Node B.

• The target Node B can change the transmission of the DL DPCH only with a step size of 256

chips, in order to be synchronised to the SCH and P-CCPCH structure.

• The S-RNC informs also the UE about the Frame Offset.

T =

Tm =timing differencerange: 0..38399Res.: 1 chip

SRNC

Relative timingbetween DL DPCHand P-CCPCHrange: 0..38144res.: 256 chips

Offsetbetween DL DPCHand P-CCPCHrange: 0..38399res.: 1 chip

Radio Interface Synchronisation


UEcell1

T0 =1024chips

cell2= target

cell for HO

(Frame Offset, Chip Offset)

res.: 1 chip

(Frame Offset)(TM)


Blank Page


Part VIIDedicated Physical Channel Uplink


• The uplink dedicated physical channel transmission, we identify two types of physical channels:

• Dedicated Physical Control Channel (DPCCH),• Which is always transmitted with spreading factor 256.

• Following fields are defined on the DPCCH:

• pilot bits for channel estimation. Their number can be 3, 4, 5, 6, 7 or 8.

• Transmitter Power Control (TPC), with either one or two bits

• Transport Format Combination Indicator (TFCI), which is optional, and a

• Feedback Indicator (FBI). Bits can be set for the closed loop mode transmit diversity

and site selection diversity transmission (SSDT)

• 6 different slot formats were specified for the DPCCH. Variations exist for the compressed

mode.

Uplink Dedicated Physical Channels


mode.

• Dedicated Physical Data Channel (DPDCH),• Which is used for user data transfer.

• Its spreading factor ranges between 4 and 256.

• 7 different solt formats are defined, which are set by the higher layers.

• The DPCCH and DPDCH are combined by I/Q code multiplexing with each multiframe.

• Multicode usage is possible. If applied, additional DPDCH are added to the uplink transmission, but no

additional DPCCHs! The maximum number of DPDCH is 6.

• The transmission itself is organised in 10 ms radio frames, which are divided into 15 timeslots. The

timeslot length is 2560 chips.


10 ms Frame

Radio Frame0

Radio Frame1

Radio Frame2

Radio Frame71

Superframe = 720 ms

Uplink Dedicated Physical Channels


TPCbits

Pilot bitsTFCI bits(optional)

Data 1 bitsDPDCH

DPCCH FBI bits

• 7 different slot formats

• 6 different slot formats• Compressed mode slot

format for changed SF & changed puncturing

Feedback Indicator for• Closed loop mode transmit diversity, &• Site selection diversity transmission (SSDT)

• Discontinuous transmission (DTX) is supported for the DCH both uplink and downlink.

• If DTX is applied in the downlink – as it is done with speech – then 3000 bursts are generated in one

second. (1500 times the pilot sequence, 1500 times the TPC bits)

• This causes two problems:

• Inter-frequency interference, caused by the burst generation.

• At the Node B, the problem can be overcome with exquisite filter equipment. This filter

equipment is expensive and heavy. Therefore it cannot be applied in the UE.

• The UE‘s solution is I/Q code multiplexing, with a continuous transmission for the DPCCH.

DPDCH changes can still occur, but they are limited to the TTI period. The minimum TTI

period is 10 ms. The same effects can be observed, then the DPDCH data rate and with it its

output power is changing.

Discontinuous Transmission and Power Offsets


output power is changing.

• 3000 bursts causes audible interference with other equipment – just see for example GSM.

• By reducing the changes to the TTI period, the audible interference is reduced, too.

• Determination of the power difference between the DPCCH and DPDCH• I/Q code multiplexing is done in the uplink, i.e. the DPCCH and DPDCH are transmitted with

different codes (and possible with different spreading factors). Gain factors are specified: ββββc is the

gain factor for the DPCCH, while ββββd is the gain factor for the DPDCH. The gain factors may vary

for each TFC. There are two ways, how the UE may learn about the gain factors:

• The gain factors are signalled for each TFC. If so, the nominal power relation Aj between

the DPDCH and DPCCH is ββββd/ββββc.

• The gain factor is calculated based on reference TFCs. (The details for gain factor calculation

based on reference TFCs are not discussed in this course.)

DPCCH

DPDCH

DPCCH

DPDCH

DPCCH

DPDCH

TTL TTL TTL

Discontinuous Transmission and Power Offsets


UL DPDCH/DPCH Power Difference:

DPCCH

DPDCH

=ββββd

ββββc

=Nominal Power Relation Aj

two methods to determine the gain factors:

• signalled for each TFCs

• calculation based on reference TFCs

• The subscriber is mobile. The distance of the UE from a Node B is changing over time.

• With growing distance and a fixed output power at the UE, the received signals at the Node B

become weaker.

• UE output power adjustment is required.

• But the UE‘s received signal strength can change fast – Rayleigh fading in one phenomena,

which causes this event.

• As a consequence, a fast UL power control is required.

• This power control is called UL inner loop power control, though many experts also call it (fast)

closed loop power control.

• At each active set cell, a target SIR (SIR ) is set for each UE. The active set cells estimate SIRest

UL Inner Loop Power Control


• At each active set cell, a target SIR (SIRtarget) is set for each UE. The active set cells estimate SIRest

on the UE‘s receiving uplink DPCH. Each active set cell determines the TPC value. If the estimated

SIR is larger than the UE‘s target SIR, then the determined TPC value is 0. Otherwise it is 1. These

values are determined on timeslot basis and returned on timeslot basis.

• The UE has to determine the power control command (TPC_cmd). The higher layer control

protocol RRC is used to inform the UE, which power control algorithm to apply. This informs the UE

also how to generate a power control command from the incoming TPC-values.

There are power control algorithm 1 (PCA1) and 2 (PCA2), which are described in the figure

following the next one. Given the power control algorithm and the TPC-values, the UE determines,

how to modify the transmit power for the DPCCH: ∆∆∆∆DPCCH = ∆∆∆∆ TPC ×××× TPC_cmd. ∆∆∆∆ TPC stands for the

transmission power step size.

(continued on the next text slide)

SIRest

SIRtarget



time

TPC ⇒⇒⇒⇒TPC_cmd

in FDD mode:1500 times per second

• Power Control Algorithm 1• is applied in medium speed environments.

• Here, the UE is commanded to modify its transmit power every timeslot.

• If the received TPC value is 1, the UE increases the transmission output at the DPCCH by

∆∆∆∆DPCCH, otherwise it decreases it by ∆∆∆∆DPCCH. • The ∆∆∆∆DPCCH is either 1 or 2 dB, as set by the higher layer protocols.

• TPC values from the same radio link set represent one TLC_cmd.

• TPC_cmds from different radio link sets have to be weighted, if there is no reliable

interpretation.

• Power Control Algorithm 2



• Power Control Algorithm 2• was specified to allow smaller step sizes in the power control in comparison to PCA1.

• This is necessary in very low and high speed environments.

• In these environments, PCA1 may result in oscillating around the target SIR.

• PCA2 changes only with every 5th timeslot, i.e. the TPC_cmd is set to 0 the first 4 timeslots.

In timeslot 5, the TPC_cmd is –1, 0, or 1.

• For each radio set, the TPC_cmd is temporarily determined. This can be seen in the next

figure.

• The temporary transmission power commands (TPC_temp) are combined as can be seen in

the figure after the next one. Here you can see, how the final TPC_cmd is determined.

Note that up to NSN RU 10 only PCA 1 is supported.

algorithms for processing power control commands TPC_cmd

PCA1

TPC_cmd for each TSTPC_cmd values: +1, -1step size ∆∆∆∆ : 1dB or 2dB

PCA2

TPC_cmd for 5th TSTPC_cmd values: +1, 0, -1step size ∆∆∆∆ : 1dB


Note that up to NSN RU 10

only PCA 1 is supported.


PCA2 PCA1 PCA2

step size ∆∆∆∆ TPC: 1dB or 2dB step size ∆∆∆∆ TPC: 1dB

UL DPCCH power adjustment: ∆∆∆∆DPCCH = ∆∆∆∆ TPC ×××× TPC_cmd

km/h0 ≈≈≈≈ 3 ≈≈≈≈ 80Rayleigh fading can be compensated

Example: reliable transmission

Cell 3

TPC3 = 1⇒⇒⇒⇒

TPC_cmd = -1 (Down)

Power Control Algorithm 1


Cell 1Cell 2

TPC1 = 1 TPC3 = 0

Note that up to NSN RU 10 only PCA 1 is supported.

TPC_temp

0

0

0

0

1

0

• if all TPC-values = 1

⇒ TPC_temp = +1

• if all TPC-values = 0

⇒ TPC_temp = -1

• otherwise

⇒ TPC_temp = 0

Power Control Algorithm 2 (part 1)


0

0

0

0

0

0

0

0

0

-1

⇒ TPC_temp = 0

Note that up to NSN RU 10 PCA 2 is not supported.

TPC_temp1 TPC_temp2 TPC_temp3

Example:

N = 3

Power Control Algorithm 2 (part 2)


∑=

N

i

i

N 1

TPC_temp1

-1 -0.5 0 0.5 1

TPC_cmd = -1 10

Note that up to

RU 10 PCA 2 is

not supported.


Blank Page


• UTRAN shall start the transmission of the downlink DPCCH and may start the transmission of DPDCH

if any data is to be transmitted.

• The UE uplink DPCCH transmission shall start

• When higher layers consider the downlink physical channel established, if no activation time

for uplink DPCCH has been signalled to UE

• If an activation time has been given, uplink DPCCH transmission shall not start before the

downlink physical channel has been established and the activation time has been reached.

• When we look to the PRACH, we can see, that preambles were used to avoid UEs to access UTRAN

with a too high initial transmission power.

• The same principle is applied for the DPCH.

• The UE transmits between 0 to 7 radio frames only the DPCCH uplink, before the DPDCH is code

Initial Uplink DCH Transmission


• The UE transmits between 0 to 7 radio frames only the DPCCH uplink, before the DPDCH is code

multiplexed.

• The number of radio frames is set by the higher layers (RRC resp. the operator).

• Also for this period of time, only DPCCH can be found in the downlink.

• The UE can be also informed about a delay regarding RRC signalling – this is called SRB delay,

which can also last 0 to 7 radio frames. The SRB delay follows after the DPCCH preamble.

• How to set the transmission power of the first UL DPCCH preamble?

• Its power level is

• DPCCH_Initial_power = – CPICH_RSCP + DPCCH_Power_offset• The DPCCH Power Offset is retrieved from RRC messages. It’s value ranges between –164

and –6 dB (step size 2 dB). CPICH_RSCP is the received signal code power on the P-

CPICH, measured by the UE.

receptionat UE

DPCCH only DPCCH & DPDCH

Initial Uplink DCH Transmission


trans-mission

at UE

DPCCH only DPCCH & DPDCH

0 to 7 frames for power control preamble

DPCCH_Initial_power = – CPICH_RSCP + DPCCH_Power_offset

DL Synch & Activation time

0 to 7 frames ofSRB delay

Part VIIIHSDPA Physical Channels


High Speed Physical Downlink Shared Channel(HS-PDSCH)The WCDMA system normally carries user data over dedicated transport channels, or DCHs, which brings maximum system performance with continuous user data. The DCHs are code multiplexed onto one RF carrier. In the future, user applications are likely to involve the transport of large volumes of data that will be burst in nature and require high bit rates.

HSDPA introduces a new transport channel type, High Speed Downlink Shared Channel (HS-DSCH) that makes efficient use of valuable radio frequency resources and takes into account bursty packet data. This new transport channel shares multiple access codes, transmission power and use of infrastructure hardware between several users. The radio network resources can be used efficiently to serve a large number of users who are accessing to the resources and so forth. In other words, several users can be time multiplexed so that during silent


can be used efficiently to serve a large number of users who are accessing to the resources and so forth. In other words, several users can be time multiplexed so that during silent periods, the resources are available to other users.

HSDPA offers maximum peak rates of up to 14.4 Mbps in a 5 MHz channel. However, more important than the peak rate is the packet data throughput capacity, which is improved significantly. This increases the number of users that can be supported at higher data rates on a single radio carrier.

Another important characteristic of HSDPA is the reduced variance in downlink transmission delay. A guaranteed short delay time is important for many applications such as interactive games. In general, HSDPA’s enhancements can be used to implement efficiently the ‘interactive’ and ‘background’ Quality of Service (QoS) classes standardized by 3GPP. HSDPA’s high data rates also improve the use of streaming applications on shared packet channels, while the shortened roundtrip time will benefit web-browsing applications.

L1 Feedback

Data

•Shared DL data channel

•Fast link adaptation, scheduling and L-1

• Channel quality information

• Error correction Ack/Nack

HSDPA – General principle


Terminal 1 (UE)

Terminal 2

L1 Feedback

Data

Data

scheduling and L-1 error correction done in BTS

•1 – 15 codes (SF=16)

•QPSK or 16QAM modulation

•User may be time and/or code multiplexed.

HSDPA features

HSDPA enhanced data rates and spectrum efficiency HSDPA improves system capacity and increases user data rates in the downlink direction, that is, transmission from the radio access network to the mobile terminal. This improved performance is based on:

• 1) adaptive modulation and coding

• 2) a fast scheduling function, which is controlled in the base station (BTS), rather than by the radio network controller (RNC).

• 3) fast retransmissions with soft combining and incremental redundancy


• 3) fast retransmissions with soft combining and incremental redundancy

Fast scheduling

• Scheduling of the transmission of data packets over the air interface is performed in the base station based on information about the channel quality, terminal capability, QoS class and power/code availability. Scheduling is fast because it is performed as close to the air interface as possible and because a short frame length is used.

HSDPA features

Fast Link Adaptation: Modulation and Coding is

Fast Packet Scheduling:The NodeB is responsible for resource allocation to HSDPA Fast H-ARQ:

HSDPA

Fast LinkAdaptation

FastH-ARQ

FastPacket

scheduling


Modulation and Coding is adapted every 2 ms (1 TTI) during the session to the radio link quality. This ensures highest possible data rates to end-users.

resource allocation to HSDPA packet data users. Resource allocation is performed every TTI = 2 ms. For resource allocation, the users radio link quality may be taken into account.Fast Packet Scheduling improves the spectrum efficiency.

Fast H-ARQ: Data are retransmitted by BTS. UE

acknowledges (L1) and performs soft combination of initial

transmission & retransmissions. This provides reliable, fast and

efficient data transmission.

Interaction of MAC-hs and Physical Layer

HSDPA Peak Bit Rates

Coding rate

QPSK

Coding rate

1/4

2/4

3/4

5 codes 10 codes 15 codes

600 kbps 1.2 Mbps 1.8 Mbps

1.2 Mbps 2.4 Mbps 3.6 Mbps



16QAM

2/4

3/4

4/4




RAS06 allows allocation of up to 15 Codes; 14.4 Mbps total;

up to 3 simultaneous user; max. 10 Mbps/user

RU10 allows max. 14.4 Mbps/user

BTS

Associa

ted D

PC

H

Associa

ted D

PC

H

15 x

HS

-P

DS

CH SC

CH

DP

CC

H

DL CHANNELS

HS-PDSCH: High-Speed Physical Downlink Shared Channel

HS-SCCH: High-Speed SharedControl Channel

F-DPCH: Fractional Dedicated Physical Channel

Associated DPCH, Dedicated

Rel99 DCH

Physical Channels for One HSDPA UE

DP

CH


UE

Associa

ted D

PC

H

Associa

ted D

PC

H

1-1

5 x

HS

PD

SC

H

1-4

x H

S-S

CC

H

HS

-DP

CC

H

Associated DPCH, DedicatedPhysical Channel.

UL CHANNELS

Associated DPCH, DedicatedPhysical Channel

HS-DPCCH: High-Speed Dedicated Physical Control Channel

F-D

PC

H

HSDPA DL physical channels

HS-PDSCH: High-Speed Physical Downlink Shared Channel

• Transfers actual HSDPA data of HS-DSCH transport channel.

• 1-15 code channels.

• QPSK or 16QAM modulation.

• Divided into 2ms TTIs

• Fixed SF16

• Doesn’t have power controlField Number of


HS-SCCH: High-Speed Shared Control Channel

• Includes information to tell the UE how todecode the next HS-PDSCH frame

• Fixed SF128

• Shares downlink power with the HS-PDSCH

• More than one HS-SCCH required when codemultiplexing is used

• Power can be controlled by node B(proprietary algorithms)

Field Number of

uncoded bits

Channelisation code set information 7 bits

Modulation scheme information 1 bit

Transport block size information 6 bits

Hybrid ARQ process information 3 bits

Redundancy and constellation version 3 bits

New data indicator 1 bit

UE identity 16 bits

HSDPA DL physical channels

F-DPCH: Fractional Dedicated Physical Channel

• The F-DPCH carries control information generated at layer 1 (TPC commands).

• It is a special case of DL DPCCH

• fixed SF = 256

• Frame structure of the F-DPCH: each 10 ms frame is split into 15 slots (each of 2/3 ms), corresponding to 1 power-control period

• Up to 10 users can share the same F-DPCH to receive power control information (per user: 2 F-DPCH bits/slot = 1.5 ksymb/s).


user: 2 F-DPCH bits/slot = 1.5 ksymb/s).

• Introduced in Rel. 6 for situations where only packet services are active in the DL others than the Signalling Radio Bearer SRB

• Should be used in case of low data rate packet services handled by HSDPA & HSUPA, where the associated DPCH causes to much (power) overhead and code consumption

Associated DPCH, Dedicated Physical Channel

• Transfers L3 signalling (Signalling Radio Bearer (SRB)) information e.g. RRC measurement control messages

• Power control commands for associated UL DCH

• DPCH needed for each HSDPA UE.

HSDPA UL physical channelsHS-DPCCH: High-Speed Dedicated Physical Control Channel

• MAC-hs Ack/Nack information (send when data received).

• Channel Quality Information, CQI reports (send in every 4ms)

• SF 256

• Power control relative to DPCH

• No SHO



• DPCH needed for each HSDPA UE.

• Transfers signalling

• Also transfers uplink data 64, 128, 384kbps, e.g. TCP acks and UL data transmission

Physical channel structure – Time multiplexing

3GPP enables time and code multiplexing.

Picture presents time multiplexing

• One HS-SCCH

UE1

UE1

UE1

UE2

UE2

UE2

UE1

HS-PDSCH #2

UE1

UE1

UE1

UE2

UE2

UE2

UE3

UE3

UE3

UE1

HS-PDSCH #1

UE1

UE1

UE1

UE1

HS-PDSCH #3

1 radio frame (15 slots, total 10 ms)

2 ms

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Subframe #1 Subframe #2 Subframe #3 Subframe #4 Subframe #5

User data on HS-DSCH

2 slots


• One HS-SCCH required per cell

• Codes can be allocated only to one user at a time

E1 E1 E1 E1HS-PDSCH #3

UE #1

UE #2

UE #3

UE1

UE1

UE1

UE2

UE2

UE2

UE3

UE3

UE3

UE1

HS-SCCH

L1 feedback HS-DPCCH

3 slots



Code Multiplexing

With Code Multiplexing, multiple UEs can be scheduled during one TTI.

Multiple HS-SCCH channels

• One for each simultaneously receiving UE.

• HS-SCCH power overhead.

HS-PDSCH codes divided for

HS-PDSCH

HS-PDSCH

HS-PDSCH

HS-PDSCH

HS-PDSCH

HS-PDSCH

HS-PDSCH

HS-PDSCH

HS-SCCH

HS-SCCH


HS-PDSCH codes divided for different transport blocks.

• Multiple simultaneous transport blocks to one UE not possible.

Codes can be allocated to multiple users at same time

• Important when cell supports more codes than UEs do. For example 10 codes per cell, UE category 6.

cat 6

HS-PDSCH

HS-PDSCH

HS-PDSCH

cat 6 cat 6 cat 6cat 8

HS-SCCH

HS-PDSCH

2 slots 3 slots

P-CCPCH

TTX_diff

Downlink DPCH

Tprop + 7.5 slots

Unit = chips2560 chips = slot3 slots = (HSDPA) subframe15 slots = frame

Timing of HSDPA Physical Channels


HS-DPCCH

Node B

UE

Uplink DPCH

Downlink DPCH

Tprop + 0.4 slots (1024 chips)

m x 0.1 slots = TTX_diff + 10.1 slots

SF = 32

SF = 8

SF = 16

SF = 4

SF = 2

SF = 1

Codes for 5

Downlink Code Allocation example


SF = 128

SF = 256

SF = 64

Codes for the cell common channels

Code for one

HS-SCCH

Codes for 5

HS-PDSCH's

•166 codes @ SF=256 available for the associated DCHs and non-HSDPA uses

Adaptive Modulation and Coding

Link adaptation in HSDPA is the ability to adapt the modulation scheme and coding according to the quality of the radio link.

The spreading factor remains fixed, but the coding rate can vary between 1/4 and 3/4.

The HSDPA specification supports the use of 5, 10 or 15 multi-


The HSDPA specification supports the use of 5, 10 or 15 multi-codes.

Link adaptation ensures the highest possible data rate is achieved both for users with good signal quality (higher coding rate), typically close to the base station, and for more distant users at the cell edge (lower coding rate).

Fast Link Adaptation in HSDPA

02468

10121416

stan

taneo

us

EsN

o [d

B] C/I received by

UEC/I varies

with fading


0 20 40 60 80 100 120 140 160-2

0

Time [number of TTIs]

QPSK1/4

QPSK2/4

QPSK3/4

16QAM2/4

16QAM3/4

Ins

Link adaptation

mode

BTS adjusts link adaptation mode with a few ms delay based on channel quality reports from

the UE

1011 1001

10001010

0001 0011

00100000

0100 01101110 1100

Q

I

10 00

0111

Q

I

Link adaptation: Modulation


QPSK

2 bits / symbol =480 kbit/s/HS-PDSCH =

max. 7.2 Mbit/s

16QAM

4 bits / symbol =960 kbit/s/HS-PDSCH =

max. 14.4 Mbit/s

0111010111011111

3GPP Rel. 7 introduces DL 64QAM support for HS-PDSCH

UE HS-DSCH physical layer categoriesMaximum number of HS-DSCH codes received

• Defines the maximum number of HS-DSCH codes the UE is capable of receiving.

Total number of soft channel bits in HS-DSCH

• Defines the maximum number of soft channel bits over all HARQ processes

• When explicit signalling is used UTRAN configures Process Memory Size for each HARQ process so that the following criterion must be fulfilled in the configuration:

– Total number of soft channel bits in HS-DSCH ≥ sum of Process Memory Size


– Total number of soft channel bits in HS-DSCH ≥ sum of Process Memory Size of all the HARQ processes.

Minimum inter-TTI interval in HS-DSCH

• Defines the distance from the beginning of a TTI to the beginning of the next TTI that can be assigned to the UE.

UEs of Categories 11 and 12 support QPSK only.

3GPP Rel. 7 introduces Categories 13 – 18 for 64QAM or MIMO support

3GPP Rel. 8 introduces Categories 19 & 20 for 64QAM & MIMO support

See 3GPP TS25.306

UE HS-DSCH physical layer categoriesHS-DSCH category

Maximum number of HS-DSCH codes

received

Minimum inter-TTI interval

Maximum number of bits of an HS-DSCH transport

block received within an HS-DSCH TTI

ARQ Type at maximum data rate

Total number of soft

channel bits

Category 1 5 3 7298 Soft 19200

Category 2 5 3 7298 IR 28800


Category 4 5 2 7298 IR 38400


Category 6 5 1 7298 IR 67200

TS 25.306

QPSKor

16QAM


Category 6 5 1 7298 IR 67200

Category 7 10 1 14411 Soft 115200

Category 8 10 1 14411 IR 134400

Category 9 15 1 20251 Soft 172800

Category 10 15 1 27952 IR 172800

Category 11 5 2 3630 Soft 14400

Category 12 5 1 3630 Soft 28800

QPSKonly

16QAM

• 3GPP Rel. 7 introduces Categories 13 – 18 for 64QAM or MIMO support

• 3GPP Rel. 8 introduces Categories 19 & 20 for 64QAM & MIMO support

CQI mapping – UE Category 1-6

“Based on an unrestricted observation interval, the UE shall report the highest tabulated CQI value for which a single HS-DSCH sub-frame formatted with the transport block size, number of HS-PDSCH codes and modulation corresponding to the reported or lower CQI value could be received in a 3-slot reference period ending 1 slot before the


reference period ending 1 slot before the start of the first slot in which the reported CQI value is transmitted and for which the transport block error probability would not exceed 0.1.”

TS 25.214

BTS

Associa

ted D

PC

H

Associa

ted D

PC

H

15 x

HS

-P

DS

CH SC

CH

DP

CC

H

Rel99 DCH

Channel quality indication (CQI) from HSDPA UEUE reports the channel conditions to the base station via the uplink channel CQI field on the HS-DPCCH

UE estimates which AMC format � CQI (0…30) will provide transport block error probability < 10 % on HS-DSCH


UE

Associa

ted D

PC

H

Associa

ted D

PC

H

1-1

5 x

HS

PD

SC

H

1-4

x H

S-S

CC

H

HS

-DP

CC

H

10 % on HS-DSCH

WBTS uses CQI as one input when defining the AMC format used on the HS-PDSCH

• Transport Block Size

• Number of HS-PDSCH (codes)

• Modulation

• Incremental redundancy

MAC-hsUE: The MAC-hs handles the HS-DSCH specific functions. In the model below the MAC-hs comprises the following entity:

• HARQ:

– The HARQ entity is responsible for handling the HARQ protocol. There shall be one HARQ process per HSDSCH per TTI. The HARQ functional entity handles all the tasks that are required for hybrid ARQ. It is for example responsible for generating ACKs or NACKs. The detailed configuration of the hybrid ARQ protocol is provided by RRC over the MAC-Control SAP.

• Reordering:

– The reordering entity organises received data blocks according to the received TSN. Data blocks with consecutive TSNs are delivered to higher layers upon reception. A timer mechanism determines delivery of nonconsecutive data blocks to higher layers. There is one reordering entity


determines delivery of nonconsecutive data blocks to higher layers. There is one reordering entity for each priority class.

RNC: The MAC-hs is responsible for handling the data transmitted on the HS-DSCH. Furthermore it is responsible for the management of the physical resources allocated to HS-DSCH. MAC-hs receives configuration parameters from the RRC layer via the MAC-Control SAP. There shall be priority handling per MAC-d PDU in the MAC-hs. The MAC-hs is comprised of four different functional entities:

• Flow Control

• Scheduling/Priority Handling

• HARQ

• TFRI selection

MAC-hs

UE: RNC:


HS-SCCH

HS-DSCH

HS-DPCCH

Flow control

This is the companion flow control function to the flow control function in the MAC-c/sh in case of Configuration with MAC-c/sh and MAC-d in case of Configuration without MAC-c/sh.

Both entities together provide a controlled data flow between the MAC-c/sh and the MAC-hs (Configuration with MAC-c/sh) or the MAC-d and MAC-hs (Configuration without MAC-c/sh) taking the transmission capabilities of the air interface into account in a dynamic


transmission capabilities of the air interface into account in a dynamic manner.

This function is intended to limit layer 2 signalling latency and reduce discarded and retransmitted data as a result of HS-DSCH congestion.

• Iub congestion

• MAC-d buffer overflow in MAC-hs

Flow control is provided independently per priority class for each MAC-d flow.

Scheduling/Priority Handling

This function manages HS-DSCH resources between HARQ entities and data flows according to their priority class.

Based on status reports from associated uplink signalling either new transmission or retransmission is determined.

Further it sets the priority class identifier and TSN for each new data block being serviced. To maintain proper transmission priority a new transmission can be initiated on a HARQ process at any time. The


transmission can be initiated on a HARQ process at any time. The TSN is unique to each priority class within a HS-DSCH, and is incremented for each new data block.

It is not permitted to schedule new transmissions, including retransmissions originating in the RLC layer, within the same TTI, along with retransmissions originating from the HARQ layer.

HARQ and TFRI selectionHARQ:

• One HARQ entity handles the hybrid ARQ functionality for one user.

• One HARQ entity is capable of supporting multiple instances (HARQ process) of stop and wait HARQ protocols.

• There shall be one HARQ process per TTI.

• The HARQ protocol is based on an asynchronous downlink and synchronous uplink scheme.

• The ARQ combining scheme is based on Incremental redundancy.

– Chase Combining is considered to be a particular case of Incremental Redundancy.


– Chase Combining is considered to be a particular case of Incremental Redundancy. The UE soft memory capability shall be defined according to the needs for Chase combining. The soft memory is partitioned across the HARQ processes in a semi-static fashion through upper layer signalling. The UTRAN should take into account the UE soft memory capability when configuring the different transport formats (including possibly multiple redundancy versions for the same effective code rate) and when selecting transport formats for transmission and retransmission.

TFRI selection:

• Selection of an appropriate transport format and resource combination for the data to be transmitted on HSDSCH.

L1 error correction – HARQHybrid ARQ is a combination of

• Forward error correction (channel coding) and

• Automatic Repeat Request (retransmissions).

HARQ performs retransmissions of MAC-hs PDUs from Node B to UE.

HARQ processes

• Typically 6 per UE (depends).

• Stop-and-wait ARQ per process.

• Processes operate in parallel.

NACK feedback status:


NACK feedback status:

• “Yes” means NACK is received for this HARQ process from the UE

• “No” means ACK/NACK has not received yet

• “DTX” means ACK/NACK was not received in predefined time period.

Transmitter chooses Redundancy Version (RV) for each transmission.

Receiver performs combining of different transmission of same MAC-hs PDU.

• Chase Combining.

• Incremental Redundancy.

• Constellation Rearrangement (16QAM only).

• Fast retransmissions

Server RNC Node-BMAC-hs Layer-1

retransmissions

Retransmissions in HSDPA


UE

RLC retransmissions

TCP retransmissions

HSDPA L1 RetransmissionsThe L1 retransmission procedure (Hybrid ARQ, HARQ) achieves following

• L1 signaling to indicate need for retransmission -> fast round trip time facilitated between UE and BTS

• Decoder does not get rid off the received symbols when decoding fails but combines the new transmisssion with the old one in the buffer.


There are two ways of operating:

• A) Identical retransmission (soft/chase combining): where exactly same bits are transmitted during each transmission for the packet

• B) Non-identical retransmission (incremental redundancy): Channel encoder output is used so that 1st transmission has systematic bits and less or not parity bits and in case retransmission needed then parity bits (or more of them) form the second transmission.

Systematic

Parity 1

Parity 2

Turbo Encoder

Rate Matching (Puncturing)

Systematic

Original transmission Retransmission

HSDPA L1 Retransmissions : Chase Combining


Parity 1

Parity 2

Chase Combining (at Receiver)

Systematic

Parity 1

Parity 2

Systematic

Parity 1

Parity 2

Turbo Encoder

Rate Matching (Puncturing)

Systematic

Original transmission Retransmission

HSDPA L1 Retransmissions : Incremental Redundancy


Parity 1

Parity 2

Incremental Redundancy Combining

Systematic

Parity 1

Parity 2

Power control on HSDPA channels

Associated UL and DL DPCH utilise normal closed loop power control

DL HS-PDSCH

• Fixed power or variable power e.g. according to load conditions

DL HS-SCCH

• 3GPP specifications do not explicitly specify any closed loop PC modes for the HS-SCCH

• The Node-B must rely on feedback information from the UE related to the reception quality of other channel types, such as:

– Power control commands for the associated DPCH

– CQI reports for HS-DSCH


– CQI reports for HS-DSCH

– ACK/NACK feedback or DTX in uplink HS-DPCCH

UL HS-DPCCH

• Based on associated DPCH power control with power offsets

• The power offset parameters [∆ACK; ∆NACK; ∆CQI] are controlled by the RNC and reported to the UE using higher layer signalling

HS-DPCCH

DPCCH

∆ACK; ∆NACK ∆CQI ∆CQI

Ack/Nack CQI report

Part IXHSUPA Physical Channels


High Speed Uplink Packet Access (HSUPA)

HSUPA or High Speed Uplink Packet Access is used for the UMTS Rel. 6 counterpart and in analogy to Rel. 5 HSDPA. Nevertheless, HSUPA has been specified by 3GPP under the term „FDD Enhanced Uplink“. The scope of HSUPA is identical to that of HSDPA: to improve the overall radio resource efficiency, leading to higher capacity respectively throughput per cell as well as higher peak data rates per user / connection.

HSUPA introduces a new transport channel type, Enhance Dedicated Channel (E-DCH), a transport channel that is dedicated to only 1 UE and subject to Node-B scheduling and HARQ. The E-DCH is defined as an extension to DCH transmission.


HSUPA offers maximum data rates of 1920kbps in single code operation (1 code of SF=2) or up to 5.76Mbps by allowing multicode operation (2 codes of SF=2 + 2 codes of SF=4).

HSUPA brings benefits for both the operators and the end users. In practice, it means higher data rates for end users, larger coverage especially for high bit rates, lower delay in case of transmission failures, larger capacity in the radio network and the opportunity for the operator to deliver services (the existing ones and the new ones) at a lower cost of bit.

2-allocation of

• Channel quality Information

• Error correction Ack/Nack

HSUPA – General principle

1-Scheduling request

to Node B

• E-DCH

• Node B controlled scheduling

• HARQ


UE

4-L1 Feedback

2-allocation of

allowed PWR (resources)

3-Data tx

5-More or less PWR is granted if

needed

• HARQ

• SF=256-2

• Multi-Code operation

• QPSK modulation only Dual-branch BPSK on I- & Q-

branch

• Fast Link Adaptation(Adaptive Coding), no enhanced/ adaptive modulation in Rel. 6

• SHO supported

HSUPA features

HSUPA enhanced data rates and spectrum efficiency

HSUPA improves system capacity and increases user data rates in the uplink direction, that is, transmission from the mobile terminal to the radio access network. This improved performance is based on:

• 1) Fast Link Adaptation using adaptive coding (1/4 -3/4, 4/4 with high level equipment). In HSUPA, no adaptive modulation takes part in UMTS Rel. 6.

• 2) Fast Node B UL scheduling function: This is controlled in the base station (BTS), rather than by the radio network controller (RNC). It gives the possibility


(BTS), rather than by the radio network controller (RNC). It gives the possibility for the Node B to control, within the limits set by the RNC, the set of TFCs from which the UE may choose a suitable TFC (Transport Format Combination). Is fast because it is performed as close to the air interface as possible and because a short frame length is used.

• 3) Fast HARQ: terminated at the Node B, with soft combining or incremental redundancy. It allows lower retransmission delay in case of transmission failure, since re-transmission is performed between the UE and the BTS, not between the RLC peers

HSUPA features

Fast Link Adaptation:HSUPA (Rel. 6): The coding is Fast H-ARQ: UE and Node B are

HSUPA

Fast LinkAdaptation Fast

H-ARQ

Fast PacketScheduling


HSUPA (Rel. 6): The coding is adapted dynamically every TTI (2 ms / 10 ms) by the UE to radio link quality. Modulation is fixed to QPSK in Rel. 6. Rel. 7 offers adaptation of the modulation (QPSK/16QAM), too.Fast Link Adaptation improves the spectrum efficiency significant.

Fast Packet Scheduling:NodeB schedules UL resource allocation (every TTI = 2/10ms).

Fast H-ARQ: UE and Node B are responsible for acknowledged PS data transmission. Data retransmission is handled by UE. NodeB performs soft combining of original and Re-transmissions to enhance efficiency. This provides fast & efficient error correction.

Physical Layer in Interaction with MAC-e

HSUPA Peak Bit Rates

Coding rate

1/4

1code x SF4 2codes x SF4 2codes x SF22codes x SF2

+ 2codes x SF4

480 kbps 960 kbps 1.92 Mbps 2.88 Mbps


3/4

4/4

720 kbps 1.46 Mbps 2.88 Mbps 4.32 Mbps

960 kbps 1.92 Mbps 3.84 Mbps 5.76 Mbps

NSN RU10 (WBTS5.0) gives support to UE categories 1-7 up to 1.92 (about 2) Mbps (2 x SF2)

per UE (only 10 ms TTI, ¼ coding)

BTS

Associa

ted D

PC

H

Associa

ted D

PC

H

DP

DC

H

DP

CC

H

RG

CH

DL CHANNELS

E-AGCH: E-DCH Absolute Grant Channel

E-RGCH: E-DCH Relative Grant Channel

E-HICH: E-DCH Hybrid ARQ Indicator Channel

Associated DPCH, Dedicated Physical

Rel99 DCH

Physical Channels for One HSUPA UE

HIC

H

AG

CH


UE

Associa

ted D

PC

H

Associa

ted D

PC

H

1-4

x E

-DP

DC

H

E-D

PC

CH

E-R

GC

H

Associated DPCH, Dedicated Physical Channel.

UL CHANNELS

E-DPDCH: Enhanced Dedicated Physical Data Channel

E-DPCCH: Enhanced Dedicated Physical Control Channel


E-H

ICH

E-A

GC

H

HSUPA UL physical channels

E-DPDCH: Enhanced Dedicated Physical Data Channel

• carries UL packet data (E-DCH)

• up to 4 E-DPDCHs for 1 Radio Link

• SF = 256 – 2 (BPSK)

• pure user data & CRC

• CRC size: 24 bit (1 CRC/TTI)

• TTI = 2 / 10 ms

• UE receives resource allocation via Grant Channels

• managed by MAC-e/-es

• Error Protection: Turbo Coding 1/3


• Error Protection: Turbo Coding 1/3

• Soft/Softer Handover support

E-DPCCH: Enhanced Dedicated Physical Control Channel

• transmits control information associated with the E-DCH

• 0 or 1 E-DPCCH for 1 Radio Link

• SF = 256

Associated DPCH, Dedicated Physical Data Channel

• DPCH needed for each HSUPA UE.

• Transfers signalling

• Also transfers uplink data 64, 128, 384kbps, e.g. TCP acks and UL data transmission

E-DCH: E-DPDCH & E-DPCCH

I

Σ

cd,1 βd

I+jQ

DPDCH1

cd,3 βd

DPDCH3

cd,5 βd

DPDCH5

Rel. `99 New in Rel. 6 for HSUPA:E-DPDCH & E-DPCCH

E-DPDCH:used to carry the E-DCH transport channel.

There may be 0, 1, 2 or 4 E-DPDCH on each radio link.

E-DPCCH:used to transmit control information associated


j

Q

cd,2 βd

DPDCH2

cd,4 βd

cc βc

DPCCH

Σ

Sdpch

DPDCH4

cd,6 βd

DPDCH6

used to transmit control information associated with the E-DCH.

Configuration #

DPDCH HS-DPCCH

E-DPDCH

E-DPCCH

1 6 1 - -

2 1 1 2 1

3 - 1 4 1

Maximum number of simultaneous UL DCHs

E-DPDCH : SF-Variation & Multi-Code Operation

CC1,0 = (1)

CC2,0 = (1,1)

CC4,0 = (1,1,1,1)

CC4,1 = (1,1,-1,-1)

CC4,2 = (1,-1,1,-1)

CC64,0

CC64,1

CC64,2

•• •

• • •

SF = 1 SF = 2 SF = 4 SF = 64SF = 8

NDPDC

H

E-

DPDCHk

CCSF,k

0

E-DPDCH1

CCSF,SF/4 if SF

≥ 4

CC2,1 if SF = 2

CC if SF = 4


CC2,1 = (1,-1)

CC4,3 = (1,-1,-1,1) CC64,63

CC64,62

0E-DPDCH2

CC4,1 if SF = 4

CC2,1 if SF = 2

E-DPDCH3

E-DPDCH4

CC4,1

1

E-DPDCH1 CCSF,SF/2

E-DPDCH2

CC4,2 if SF = 4

CC2,1 if SF = 2

E-DPDCH: SF = 256 - 2

SF = 2 ⇒⇒⇒⇒ 1920 kbit/s

Multi-Code operation:up to 2 x SF2 + 2 x SF4

⇒⇒⇒⇒ up to 5.76 Mbps

E-DPDCH & E-DPCCH frame structure and content

E-DPDCH: Data only (+ 1 CRC/TTI);SF = 256 – 2; Rchannel = 15 – 1920 kbps

Ndata = 10 x 2k+2 bit (K = 0..5)

E-DPCCH: L1 control data; SF = 256; 10 bit

1 Slot = 2560 chip = 2/3 ms

Slot #0 Slot #1 Slot #2 Slot #i Slot #14


1 subframe = 2 ms

1 radio frame, Tframe = 10 ms

k SFChannel Bit Rate[kbps]

Bit/ Fram

e

Bit/ Subfram

e

Bit/Slot

Ndata

0 64 60 600 120 40

1 32 120 1200 240 80

2 16 240 2400 480 160

3 8 480 4800 960 320

4 4 960 9600 1920 640

5 2 19201920

03840 1280

E-DPCCH content:• E-TFCI information (7 bit)

indicates E-DCH Transport Block Size; i.e. at given TTI (TS 25.321; Annex B)• Retransmission Sequence Number RSN (2 bit)

Value = 0 / 1 / 2 / 3 for:Initial Transmission, 1st / 2nd / further Retransmission

• „Happy" bit (1 bit)indicating if UE could use more resources or not

Happy 1

Not happy 0

The E-DPDCH is used for user data transmission. The Spreading Factor can be varied between 256 and 2. Multi-Code operation using up to 2 SF = 2 Codes and 2 SF=4 codes enables L1 data rates up to 5.76 Mbps.

The E-DPCCH Spreading Factor is fixed to 256; One sub-frame contains 10 information bit

The E-DPDCH and E-DPCCH frame & slot format can be found in TS 25.211(-670); 5.2.1.3.The content and mapping of the E-DPCCH information fields can be found in TS 25.212(-670); 4.9.2.

The information field consists of 3 different segments:

E-DPDCH & E-DPCCH frame structure and content


E-DCH Transport Format Combination Indicator (E-TFCI): 7 bit indicating the transport format being transmitted simultaneously on the E-DPDCHs. Via this information the receiver will be informed how many E-DPDCHs are transmitted in parallel and which Spreading Factor(s) are used (see TS 25.321 Annex B: E-DCH Transport Block Size Tables for FDD).

Retransmission Sequence Number (RSN): 2 bit informing the H-ARQ sequence number of the transport block currently being sent on E-DPDCHs. Value = 0 / 1 / 2 / 3 for Initial Transmission, 1st / 2nd / further Retransmission

Happy Bit: 1 bit indicating whether the UE needs more resources or not (TS 25.321(-670); 9.2.5.3.1 & 11.8.1.5).

HSUPA DL physical channels

E-AGCHE-DCH Absolute Grant Channel

carries DL absolute grants for UL E-DCH

contains: UE-Identity (E-RNTI) & max. UE power ratio

E-DCH absolute grant transmitted over 1 TTI (2/10 ms)

SF = 256 (30 kbps; 20 bit/Slot)

NodeB


E-RGCHE-DCH Relative Grant Channel

carries DL relative grants for UL E-DCH;

complementary to E-AGCH

contains: relative Grants („UP“, „HOLD“, „DOWN“) & UE-Identity

E-DCH relative grant transmitted 1 TTI (2/10 ms)


UE

E-DCH Radio Network Temporary Identifier:

allocated by S-RNC for E-DCH user per Cell

E-DCH transmission:after E-AGCHafter E-RGCHNon-scheduled transmission


UENodeB


UE

E-HICHE-DCH Hybrid ARQ Indicator Channel

carries H-ARQ acknowledgement indicator for UL E-DCH

contains ACK/NACK (+1; -1) & UE-Identity

E-DCH relative grant transmitted 1 TTI (2/10 ms)


NodeB


E-AGCH: E-DCH Absolute Grant Channel

• carries DL absolute grants for UL E-DCH

• contains: UE-Identity (E-RNTI) & max. UE power ratio

• E-DCH absolute grant transmitted over 1 TTI (2/10 ms)

• SF = 256 (30 kbps; 20 bit/Slot)

E-RGCH: E-DCH Relative Grant Channel

• carries DL relative grants for UL E-DCH;

• complementary to E-AGCH

• contains: relative Grants („UP“, „HOLD“, „DOWN“) & UE-Identity

• E-DCH relative grant transmitted 1 TTI (2/10 ms)

• SF = 128 (60 kbps; 40 bit/Slot)


• SF = 128 (60 kbps; 40 bit/Slot)

E-HICH: E-DCH Hybrid ARQ Indicator Channel

• carries H-ARQ acknowledgement indicator for UL E-DCH

• contains ACK/NACK (+1; -1) & UE-Identity

• E-DCH relative grant transmitted 1 TTI (2/10 ms)

• SF = 128 (60 kbps; 40 bit/Slot)


• Transfers L3 signalling (Signalling Radio Bearer (SRB)) information e.g. RRC measurement control messages

• Power control commands for associated UL DCH

• DPCH needed for each HSUPA UE.

Adaptive Coding in HSUPAIn the same way as for HSDPA, in HSUPA Turbo Coding with a code rate of 1/3 is applied. In the following rate matching according to the radio interface conditions is performed. Puncturing in case of good radio conditions, repetition in case of bad radio conditions. Similar to HSDPA the effective coding will range between 1/4 and 3/4. High level equipment will support 4/4 coding as well.

Link adaptation in HSUPA is the ability to adapt only the coding according to the quality of the radio link.

The HSUPA specification supports the use of SF 256-2 and 1-4 codes for E-DPDCH. In order to achieve the max data rates, following configurations are supported:


supported:

• 1code x SF4

• 2codes x SF4

• 2codes x SF2 (max imum supported in NSN RU 10)

• 2codes x SF2 + 2codes x SF4

Link adaptation ensures the highest possible data rate is achieved both for users with good signal quality (higher coding rate), typically close to the base station, and for more distant users at the cell edge (lower coding rate).

Adaptive Coding in HSUPA

• HSUPA adapts the Coding to the current Radio Link Quality

• HSUPA varies the effective Coding between 1/4 – 1(4/4)


NodeB

UE

1/42/43/44/4 UE

Note that support for 4/4 coding is optionally given by UE and not supported in NSN RU 10!

Modulation in HSUPA

“Dual-Branch BPSK

1-Bit Keying

• Rel. 6 defines only QPSK (“Dual-branch BPSK“) as modulation method for HSUPA.

• 16QAM Modulation (“Dual-branch QPSK”) has been regarded as to complex for initial HSUPA

• (16 QAM = Dual-branch QPSK is defined in Release 7)

• no Adaptive Modulation takes place in Rel. 6; Adaptive Modulation with QPSK/16QAM in Rel. 7


-1 1

(Q)

I

QPSK:

2-Bit Keying

16 QAM

64QAM

on both Code Trees in the UE

FDD E-DCH physical layer categories

For HSUPA 6 new UE capability classes have been defined (TS 25.306-680; Tab 5.1g).They are described in the table FDD E-DCH physical layer categories (3GPP TS25.306 UE Radio Access capabilities).

The key differences between the different classes are related to:- the UE‘s multi-code capability - the support of the 2 ms TTI. All UEs are supporting the 10 ms TTI.- the minimum Spreading Factor (minimum SF = 4 or 2).


- the minimum Spreading Factor (minimum SF = 4 or 2).

Maximum # of E-DCH codes

• Defines the maximum number of E-DCH codes the UE is capable to use for tx in UL.

FDD E-DCH physical layer categories

E- DCH

Category

max.

E-DCH

Codes

min.

SF

2 & 10 ms

TTI E-DCH

support

max. #. of

E-DCH Bits*

/ 10 ms TTI

max. # of

E-DCH Bits*

/ 2 ms TTI

Reference

combination

Class

1 1 4 10 ms only 7110 - 0.73 Mbps

2 2 4 10 & 2 ms 14484 2798 1.46 Mbps

3 2 4 10 ms only 14484 - 1.46 Mbps


4 2 2 10 & 2 ms 20000 5772 2.92 Mbps

5 2 2 10 ms only 20000 - 2.0 Mbps

6 4 2 10 & 2 ms 20000 11484 5.76 Mbps

7* 4 2 10 & 2 ms 20000 22996 11.52 Mbps

Extracted from TS 25.306: UE Radio Access Capabilities

7* category 7 is defined in 3GPP Rel 7 and supports QPSK and 16 QAM in Uplink

NSN RU10 (WBTS5.0) gives support to UE categories 1-7 up to 2 Mbps per UE (only 10 ms TTI)

MAC Architecture

UE: MAC-es / MAC-e are handling E-DCH specific functions; split between MAC-es & MAC-e in the UE is not detailed; MAC-es/MAC-e comprises following entities:

• H-ARQ: buffering MAC-e payloads & retransmit ting them

• Multiplexing: concatenating multiple MAC-d PDUs to MAC-es PDUs & multiplex 1 or multiple MAC-es PDUs to 1 MAC-e PDU

• E-TFC selection: Enhanced Transport Format Combination selection according to scheduling information (Relative & Absolute Grants) received from UTRAN via L1

UTRAN side

Node B: 1 MAC-e entity in Node B for each UE & 1 E-DCH scheduler function handle HSUPA specific functions in Node B:


functions in Node B:

• E-DCH Scheduling: manages E-DCH cell resources between UEs; implementation proprietary

• E-DCH Control: receives scheduling requests & transmits scheduling assignments.

• De-multiplexing: de-multiplexing MAC-e PDUs

• H-ARQ: generating ACKs/NACKs

S-RNC: 1 MAC-es entity for each UE in S-RNC, performing the following functions


• Macro diversity selection: for SHO (Softer HO in Node-B); delivers received MAC-es PDUs from each Node B of E-DCH AS; see reordering function

• Disassembly: Remove MAC-es header,extract MAC-d PDU’s & deliver to MAC-d

MAC Architecture: UE Side

MAC-es/MAC-e are handling E-DCH specific functions

• Split between MAC-es & MAC-e in the UE is not detailed

• comprises following entities:

• H-ARQ: buffering MAC-e payloads & re-transmitting them

• Multiplexing: concatenating multiple MAC-d PDUs → MAC-es PDUs & multiplex 1 / multiple MAC-es PDUs → 1 MAC-e PDU • E-TFC selection: Enhanced Transport Format Combination selection according to scheduling information (Relative & Absolute Grants) received from UTRAN via L1

DCCH DTCHDTCHMAC ControlCTCHBCCH CCCHPCCH


FACH RACH DSCH DCH DCHCPCH PCH FACH DSCHHS-DSCH

associated

DL Signalling

E-DCHassociated

UL Signallingassociated

DL Signalling

associated

UL Signalling

MAC-d

MAC-c/shMAC-hsMAC-es/MAC-e

MAC Architecture: UTRAN side

1 MAC-e entity in Node B for each UE &

1 E-DCH scheduler function handle HSUPA specific functions in Node B

• E-DCH Scheduling: manages E-DCH cell re-sources between UEs; implementation proprietary

• E-DCH Control: receives scheduling requests &transmits scheduling assignments.

• De-multiplexing: de-multiplexing MAC-e PDUs

• H-ARQ: generating ACKs/NACKs

DCCH DTCHDTCHMAC Control

MAC ControlCCCH CTCHBCCHPCCHMAC ControlMAC Control

MAC Control

NodeB

• 1 MAC-es entity for each UE in S-RNC


• Macro diversity selection: for SHO(Softer HO in Node-B).

delivers received MAC-es PDUs from each Node B of E-DCH AS → reordering function

• Disassembly: Remove MAC-es header, extract MAC-d PDU’s & deliver → MAC-d

RNC


FACH RACH DSCHIur or

localDCH DCH

CPCHPCH

Configuration

with MAC-c/sh

associated

DL Signalling

MAC-e MAC-hs MAC-c/sh

MAC-d

MAC-es

associated

UL Signalling

E-DCHassociated

DL Signallingassociated

UL Signalling

HS-DSCH Iub

Configuration

without MAC-c/sh

Configuration

with MAC-c/sh

HSUPA Fast Packet Scheduling

HSUPA (Rel. 6) Fast Packet Scheduling:

• Node B controlled

• resources allocated on Scheduling Request

• short TTI = 2 / 10 ms

• Scheduling Decision on basis of actual physical layer load (available in Node B)

☺ up-to date / Fast scheduling decision ⇒ high UL resource efficiency

☺ higher Load Target (closer to Overload Threshold) possible ⇒high UL resource efficiency

� L1 signalling overhead

HSUPA (Rel. 6) Fast Packet Scheduling:

• Node B controlled

• resources allocated on Scheduling Request

• short TTI = 2 / 10 ms

• Scheduling Decision on basis of actual physical layer load (available in Node B)

☺ up-to date / Fast scheduling decision ⇒ high UL resource efficiency

☺ higher Load Target (closer to Overload Threshold) possible ⇒high UL resource efficiency

� L1 signalling overhead


Scheduling Request

(buffer occupation,...)

UE

IubNode

B

Scheduling Grants

(max. amount ofUL resources to be used)

E-DCHdata transmission

E-DCHdata transmission

S-RNC

HSUPA Link Adaptation

Scheduling

Request

Node

Scheduling

Grants

MAC-e (UE) decides E-DCH Link Adaptation (TFC; effective Coding)

on basis of:

• Channel quality estimates (CPICH Ec/Io)

• Every TTI (2/10 ms)


UENode

B

Rel. 99:

Fixed

Turbo Coding 1/3

Rel. 99:

Fixed

Turbo Coding 1/3

Rel. 6 HSUPA:

dynamic Link Adaptation

⇒ effective Coding 1/4 - 4/4

⇒

☺ higher UL data rates

☺ higher resource efficiency

Rel. 6 HSUPA:

dynamic Link Adaptation

⇒ effective Coding 1/4 - 4/4

⇒

☺ higher UL data rates

☺ higher resource efficiency

HSUPA Fast H-ARQ

HSUPA: Fast H-ARQ with UL E-DCH

• Node B (MAC-e) controlled

• SAW* H-ARQ protocol • based on synchronous DL (L1) ACK/NACK• Retransmission strategies:

Incremental Redundancy & Chase Combining

• 1st Retransmission ≈≈≈≈ 40 / 16 ms (TTI = 10 / 2 ms)• limited number of Retransmissions*

• lower probability for RLC Retransmission

• Support of Soft & Softer Handover

HSUPA: Fast H-ARQ with UL E-DCH

• Node B (MAC-e) controlled

• SAW* H-ARQ protocol • based on synchronous DL (L1) ACK/NACK• Retransmission strategies:

Incremental Redundancy & Chase Combining

• 1st Retransmission ≈≈≈≈ 40 / 16 ms (TTI = 10 / 2 ms)• limited number of Retransmissions*

• lower probability for RLC Retransmission

• Support of Soft & Softer Handover

☺ Short delay times(support of QoS services)

☺ less Iub/Iur traffic

☺ Short delay times(support of QoS services)

☺ less Iub/Iur traffic


UE

Iub

NodeB

E-DCH PacketsE-DCH Packets

L1 ACK/NACKL1 ACK/NACK

RetransmissionRetransmission

MAC-e controls L1 H-ARQ:• storing & retransmitting payload• packet combining (IR & CC)

MAC-e controls L1 H-ARQ:• storing & retransmitting payload• packet combining (IR & CC)

correctly receivedpackets

correctly receivedpackets

IR: Incremental Redundancy

CC: Chase Combining

HARQ: Hybrid Automatic Repeat Request

SAW: Stop-and-Wait

* HARQ profile - max. number of

transmissions attribute

RNC

HSUPA Fast HARQHARQ protocol characteristics

• Stop- & wait-HARQ is used (SAW);

• HARQ based on synchronous DL ACK/NACKs

• HARQ based on synchr. UL retransmissions:

• There will be an upper limit to the number of retransmissions (maximum number of transmissions attribute; 11.1.1)

• Pre-emption will not be supported by E-DCH (ongoing re-transmissions will not be pre-empted by higher priority data for a particular process);

• Intra Node B macro-diversity and Inter Node B macro-diversity should be supported for


• Intra Node B macro-diversity and Inter Node B macro-diversity should be supported for the E-DCH with HARQ

• Incremental redundancy shall be supported by the specifications with Chase combining as a subcase

HSUPA HARQ Error Handling:• The most frequent error cases to be handled are the following:• NACK is detected as an ACK: the UE starts a fresh with new data in the HARQ process.

The previously transmitted data block is discarded in the UE and lost. Retransmission is left up to higher layers;

• ACK is detected as a NACK: if the UE retransmits the data block, the NW will re-send an ACK to the UE. If in this case the transmitter at the UE sends the RSN set to zero, the receiver at the NW will continue to process the data block as in the normal case

HSUPA Soft Handover

Sectorcells

Softer Handover: • UE connected to cells of same

Node B (same MAC-e entity)• combining Node B internal• no extra Iub capacity needed

Softer Handover: • UE connected to cells of same

Node B (same MAC-e entity)• combining Node B internal• no extra Iub capacity needed

Iub

Soft Handover:

UE connected to UTRAN

via different Node Bs

Soft Handover:

UE connected to UTRAN

via different Node Bs

Node B

Node B

UE

SHO Gains:

full Coverage

for HSUPA


CN

S-RNC:select E-DCHdata (MAC-es)& deliver to CN

S-RNC:select E-DCHdata (MAC-es)& deliver to CN

E-DCH Active Set:• set of cells carrying the

E-DCH for 1 UE.• can be identical / a

subset of DCH AS• is decided by the S-RNC

E-DCH Active Set:• set of cells carrying the

E-DCH for 1 UE.• can be identical / a

subset of DCH AS• is decided by the S-RNC

Iu

IubIub

Node B

RNC

Node B

Iub

RNC

E-DCH

AS

E-DCH

AS

HSUPA Soft Handover

HSUPA: Support of Soft(er) Handover

• Macro diversity is used in HSUPA, i.e. the UL data packets can be received by more than one cell. This is important for Radio Network Planning to maximise cell ranges (SHO gains); TS 25.309: 5: The coverage is an important aspect of the user experience and that it is desirable to allow an operator to provide for consistency of performance across the whole cell area..


across the whole cell area..Intra Node B macro-diversity (Softer Handover) and Inter Node B macro-diversity (SHO) should be supported for the E-DCH with HARQ.

• E-DCH active set: The set of cells which carry the E-DCH for one UE. It can be identical or a subset of the DCH active set. The E-DCH active set is decided by the S-RNC

HSUPA Power Control

TS 25.14;5.1.2

NodeB

DPCCH

• Always transmitted

• Inner-Loop Power Control!

• Setting of E-DPCCH & E-DPDCHpower relative to DPCCH power

• PtxUE < min [Ptx,maxUE; max

Ptx,cell*]


Configuration #i

DPDCH

HS-DPCCH

E-DPDCH E-DPCCH

1 6 1 - -

2 1 1 2 1

3 - 1 4 1

B

UE

UL DCH max configurations for Rel 99, HSDPA & HSUPA

Taken from specification TS 25.213;4.2.1

• Power Management/Control for E-DCHNo special power management/control mechanism is needed for E-DCH.

• Power Control: DPDCH & DPCCHThe initial UL DPCCH transmit power is set by higher layers. Subsequently the UL transmit power

control procedure simultaneously controls the power of a DPCCH & its corresponding DPDCHs (if

present). The relative transmit power offset between DPCCH & DPDCHs is determined by the network

and is computed using the gain factors signalled to the UE using higher layer signalling.

The operation of the inner power control loop, adjusts the power of the DPCCH & DPDCHs by the

same amount, provided there are no changes in gain factors. ...

Power Control


same amount, provided there are no changes in gain factors. ...

• Setting of the UL E-DPCCH and E-DPDCH powers relative to DPCCH power.

The power of the E-DPCCH and the E-DPDCH(s) is set in relation to the DPCCH. For this purpose,

gain factors are used for scaling the UL channels relative to each other.

During the operation of the UL power control procedure the UE transmit power shall not exceed a

max. allowed value which is the lower out of the max. output power of the terminal power class and a

value which may be set by higher layer signalling.

UL power control shall be performed while the UE transmit power is below the max. allowed output

power.

For this course module, following 3GPP specifications were used:

• TS 25.211 V6, Physical channels & mapping of transport channels onto physical channels

• TS 25.212 V6, Multiplexing and channel coding (FDD) • TS 25.213 V6, Spreading and modulation (FDD) • TS 25.214 V6, Physical layer procedures (FDD)

• TS 25.215 V6, Physical layer; Measurements (FDD) • TS 25.301 V6, Radio interface protocol architecture

• TS 25.302 V6, Services provided by the physical layer

• TS 25.306 V5 – V8: UE Radio Access capabilities

References


• TS 25.306 V5 – V8: UE Radio Access capabilities• TS 25.308 V6, High Speed Downlink Packet Access (HSDPA); Overall description• TS 25.309 V6, FDD Enhanced UL (HUSPA); Overall description

• TS 25.321 V6, Medium Access Control (MAC) protocol specification• TS 25.331 V6, Radio Resource Control (RRC) protocol specification

• TS 25.402 V6, Synchronization in UTRAN Stage 2

• TS 25.433 V6, UTRAN Iub interface Node B Application Part (NBAP) signalling

NSN WCDMA Product documentation

Documents

02_RN31552EN10GLA0_The Physical Layer