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    SEMINAR REPORT

    ON

    HIGH SPEED PACKET ACCESS

    Submitted

    BY

    SMRITI 8CS-65

    B.Tech+MBA

    IN

    Computer Science

    SCHOOL OF ENGINEERING AND TECHNOLOGY

    JAIPUR NATIONAL UNIVERSITY

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    CANDIDATES DECLARATION

    I hereby declare that the work which is being presented in the report entitled HIGH SPEED

    PACKET ACCESS submitted to the department of Computer Science, Jaipur NationalUniversity, Jaipur (Rajasthan), is an authentic record of my work under the supervision of our

    trainees and lecturers of B.Tech Computer Science, Jaipur National University,

    Jaipur(Rajasthan).

    Smriti(8CS-65)

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    2. Acknowledgements

    I have taken efforts in this project. However, it would not have been possible without the kind

    support and help of many individuals and organizations. I would like to extend my sincere thanks

    to all of them.

    I am highly indebted to Mr.Rajeev Sharma for their guidance and constant supervision as well

    as for providing necessary information regarding the project & also for their support in

    completing the project.

    I would like to express my gratitude towards my parents & member of My College Jaipur

    National University for their kind co-operation and encouragement which help me in

    completion of this project.

    I would like to express my special gratitude and thanks to industry persons for giving me such

    attention and time.

    My thanks and appreciations also go to my colleague in developing the project and people who

    have willingly helped me out with their abilities.

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    3. CERTIFICATE

    This is to certify that the report entitled HIGH SPEED PACKET ACCESS SMRITI (8CS-65)

    is an authentic work carried out by them at JAIPUR NATIONAL UNIVERSITY under our

    guidance. The matter embodied in this project work has not been submitted earlier for the award

    of any degree or diploma to the best of our knowledge and belief.

    Mr.Rajeev Sharma(Guide)

    Lecturer (CS Department)

    Jaipur National University,Jaipur

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    TABLE OF CONTENTS

    CERTIFICATE...ii

    ACKNOWLEDGEMENT.........................................................................................iii

    ABSTRACT.............................................................................................................iv

    LIST OF CONTENTS..............................................................................................v

    LIST OF FIGURES..................................................................................................vi

    1. INTRODUCTION..........................................................................................................1

    1.1 Introduction ...............................................................................................................1

    1.2 Techniques....................................................................................................... ..........3

    1.2.1. MIMO.....3

    1.2.2. Higher order modulation....5

    1.2.3. Continuous Packet Connectivity 6

    1.2.4. Enhanced CELL_FACH operation.7

    2. HIGH SPEED PACKET ACCESS......9

    2.1Architecture....9

    3.HIGH SPEED DOWNLINK PACKET ACCESS.....13

    3.1 Introduction........13

    3.2 Enhanced Uplink Dedicated Channel...14

    4. HIGH SPEED UPLINK PACKET ACCESS..18

    4.1Introduction..................................................................................................184.2 3G UMTS HSUPA key characteristics..19

    4.3 3G HSUPA basics.20

    5. APPLICATION OF HSPA.......21

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    CONCLUSION......22

    REFERENCES......23

    LIST OF FIGURES

    Figure 1.1: New UMTS Radio Network Protocol Architecture .2

    Figure 1.2: Mapping of Channels.8

    Figure 2.1: Architecture of HSPA.......9

    Figure 3.1: Simplified HSDPA transmission scheme ...........................................................14

    Figure 3.2: Simplified E-DCH transmission scheme ................16

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    CHAPTER-1

    INTRODUCTION

    1.1. Introduction

    The demands of packet data applications have resulted in several improvements over the original

    Wideband Code Division Multiple Access (WCDMA) release 99. The downlink was improved

    in Release 5 with High Speed Packet Data Access (HSDPA), which provided high speed shared

    channel with fast link adaptation and scheduling, hybrid ARQ, and a short 2ms transmission time

    interval (TTI). The corresponding uplink enhancements were done in Release 6 with Enhanced

    Dedicated Channel (E-DCH), which allow Node B controlled scheduling of the uplink

    transmission, Hybrid ARQ, short 2ms TTI, and fast inter-cell interference suppression. Recently

    work has started to evolve the UTRAN with Long Term Evolution (LTE), providing a new air

    interface. LTE will supporting flexible spectrum allocation from 1.5MHz up to 20MHz, and will

    provide significant performance improvements in application performance and system capacity.

    For operators with existing HSPA deployments, the possibility to evolve HSPA should provide

    an easy way to update the system. For this reason work on HSPA Evolution has started in 3GPP.

    The Third Generation Partnership Program (3GPP) specifications included major improvements

    in downlink data rates and capacity in release 5 with the introduction of high-speed downlink

    packet access (HSDPA) in 2002. Similar technical solutions were applied to the uplink direction

    as part of the release 6 with high-speed uplink packet access (HSUPA) at the end of 2004. 3GPP

    release 7 in June 2007 completed a number of additional and substantial enhancements to the

    end-user performance, to the cell throughput, and to the network architecture.

    In addition to the paradigm change from using dedicated resources to making use of shared radio

    resources, the main technology changes introduced are:

    Fast Node B scheduling with adaptive coding and modulation (only downlink) to exploitthe varying radio channel and interference variations and accommodate bursty IP traffic.

    Node B based Hybrid ARQ to reduce retransmission round trip times and add robustnessto the system by allowing soft combining of retransmissions.

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    Reduced transmission time interval (TTI) for latency reduction and to support fastscheduler decisions and quick HARQ retransmissions.

    These added functionalities have been specified in several new MAC sub-layers and

    modifications of the physical layer as is depicted in Figure 1.1.

    Figure 1.1: New UMTS Radio Network Protocol Architecture

    In general retransmissions are now performed directly between Node B and the User equipment

    (UE). This reduces latency and saves resources on the Iub interface. The distributed scheduling

    performed by RNC and Node B requires an additional scheduling buffer in the Node B as well as

    having an additional flow control on the Iub interface. Furthermore the Node B needs to be made

    aware of certain Quality of Service parameter to ensure that the data transmission complies with

    the traffic requirements. Nevertheless HSDPA and HSUPA can be implemented in the standard 5

    MHz carrier of UMTS networks and can co-exist with the existing 3GPP Release 99 networks.

    In the following sections the principles of HSDPA and E-DCH are explained in more detail.

    HSPA is an amalgamation of two mobile telephony protocols, High Speed Downlink Packet

    Access (HSDPA) and High Speed Uplink Packet Access (HSUPA), that extends and improves

    the performance of existing 3rd

    generation mobile telecommunication networks utilizing the

    http://en.wikipedia.org/wiki/Mobile_telephonyhttp://en.wikipedia.org/wiki/Communications_protocolhttp://en.wikipedia.org/wiki/HSDPAhttp://en.wikipedia.org/wiki/HSUPAhttp://en.wikipedia.org/wiki/HSUPAhttp://en.wikipedia.org/wiki/HSDPAhttp://en.wikipedia.org/wiki/Communications_protocolhttp://en.wikipedia.org/wiki/Mobile_telephony
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    WCDMA protocols. A further improved 3GPP standard, Evolved HSPA (also known as

    HSPA+), was released late in 2008 with subsequent worldwide adoption beginning in 2010.

    The newer standard allows bit-rates to reach as high as 168 Mbit/s in the downlink and 22

    Mbit/s in the uplink. The first HSPA specifications supported increased peak data rates of up to 14

    Mbit/s in the downlink and 5.76 Mbit/s in the uplink. It also reduced latency and provided up to five times

    more system capacity in the downlink and up to twice as much system capacity in the uplink compared to

    original WCDMA protocols.

    These improvements are achieved in several ways:

    Shared-channel transmission, which results in efficient use of available code and powerresources in WCDMA.

    A shorter Transmission Time Interval (TTI), which reduces round-trip time and improvesthe tracking of fast channel variations.

    Link adaptation, which maximizes channel usage and enables the base station to operateat close to maximum cell power.

    Fast scheduling, which prioritizes users with the most favorable channel conditions Fast retransmission and soft-combining, which further increase capacity.

    16-QAM and 64-QAM (Quadrature Amplitude Modulation), which yields higher bit-rates.

    MIMO, which exploits antenna diversity to provide further improvements in bit-rates andsystem capacity.

    By July 2010, HSPA had been commercially deployed by over 200 operators in more than 80

    countries.

    1.2. Techniques

    1.2.1. MIMO

    Multiple-Input Multiple-Output (MIMO) is an antenna technology Sometimes called smart

    antenna technologythat is used both in transmission and receiver equipment for wireless radio

    http://en.wikipedia.org/wiki/W-CDMA_%28UMTS%29http://en.wikipedia.org/wiki/3GPPhttp://en.wikipedia.org/wiki/Evolved_HSPAhttp://en.wikipedia.org/wiki/Quadrature_Amplitude_Modulationhttp://en.wikipedia.org/wiki/MIMOhttp://en.wikipedia.org/wiki/MIMOhttp://en.wikipedia.org/wiki/Quadrature_Amplitude_Modulationhttp://en.wikipedia.org/wiki/Evolved_HSPAhttp://en.wikipedia.org/wiki/3GPPhttp://en.wikipedia.org/wiki/W-CDMA_%28UMTS%29
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    communication. MIMO uses multiple antennas to send multiple parallel signals (from

    transmitter).

    MIMO has been variously defined as two or more unique radio signals, in the same radio

    channel, where each signal carries different digital information and/or two or more radio signals

    which use beam-forming, receive combining, and spatial multiplexing.

    MIMO was first standardized in 3GPP Release 6, and was further developed in Release 7 with

    spatial multiplexing for HSPA+using Double Transmit Adaptive Array (D-TxAA). With

    MIMO, the use of multiple antennas at both transmitter and receiver allows:

    Substantial increase in peak data rates

    Significantly higher spectrum efficiency, especially in low-interference environments Increased system capacity (number of users)

    Based on simulation results presented in the report, MIMO Transmission Schemes for LTE and

    HSPA Networks, it was shown that the relatively simple MIMO transmission scheme based on

    2X2 closed-loop SM, at low user equipment (UE) speeds, can increase by 20 percent the

    downlink (DL) sector spectral efficiency relative to a single antenna transmission, as well as

    increase the cell edge efficiency by approximately 35 percent. More advanced antenna

    configurations can provide benefits that are significant for users that are receiving a strong signal

    as well as cell edge users.

    The 3GPP Rel-9 LTEspecifications, completed in March 2010, included some of the most

    advanced forms of MIMO of any standard in the industry. 3GPP has since included even more

    advanced MIMO enhancements for LTE-Advanced.

    Operators believe that, notwithstanding the basic differences in the physical layers used by

    UMTS and LTE, the benefits envisioned from MIMO in LTE can also be obtained from MIMO

    in UMTSsystems, starting in Release 7 (HSPA+). By deploying MIMO with HSPA+, an

    operators throughput speeds may double.

    http://www.4gamericas.org/index.cfm?fuseaction=page&sectionid=248http://www.4gamericas.org/index.cfm?fuseaction=page&sectionid=248http://www.4gamericas.org/index.cfm?fuseaction=page&sectionid=249http://www.4gamericas.org/index.cfm?fuseaction=page&sectionid=249http://www.4gamericas.org/index.cfm?fuseaction=page&sectionid=246http://www.4gamericas.org/index.cfm?fuseaction=page&sectionid=246http://www.4gamericas.org/index.cfm?fuseaction=page&sectionid=246http://www.4gamericas.org/index.cfm?fuseaction=page&sectionid=249http://www.4gamericas.org/index.cfm?fuseaction=page&sectionid=248
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    MIMO can be used to advance such applications as:

    Streaming video, music Video surveillance Voice over Internet Protocol (VoIP) Video conferencing Interactive gaming Mobile TV

    Wireless network operators see a need for MIMO due to its many advantages. Wireless systems

    using MIMO represent an economical way to increase user capacity, range and throughput in a

    variety of environments, most notably those which are enclosed and having low radio

    interference such as small and/or isolated cells.

    1.2.2. Higher order modulation

    One of the keys to the operation of HSDPA is the use of an additional form of modulation.

    Originally W-CDMA had used only QPSK as the modulation scheme, however under the new

    system16-QAM which can carry a higher data rate, but is less resilient to noise is also used when

    the link is sufficiently robust. The robustness of the channel and its suitability to use 16-QAM

    instead of QPSK is determined by analyzing information fed back about a variety of parameters.

    These include details of the channel physical layer conditions, power control, Quality of Service

    (QoS), and information specific to HSDPA.

    High order modulation techniques are able to provide higher data rates for high signal level links

    in the downlink. There is not the same advantage in the uplink where as there is no need to share

    channelization codes between users and the channel coding rates are therefore lower, although

    higher order modulation was introduced under Release 7.

    HSPA systems support the use of 16QAM in the downlink and QPSK in the uplink. These

    modulation schemes may provide high enough data rates given the received symbol SNRs of

    macro cell environments, however, for indoor or small-cell system deployments, higher SNRs

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    and higher order modulation (HOM) can be supported. Modulation and coding scheme (MCS)

    tables determine the best combination of modulation and coding rate for a given SNR.

    1.2.3. Continuous Packet Connectivity

    Packet-oriented features like HSDPA and E-DCH in WCDMA/UMTS systems will promote the

    subscribers" desire for continuous connectivity, where the user stays connected over a long time

    span with only occasional active periods of data transmission, and avoiding frequent connection

    termination and re-establishment with its inherent overhead and delay.

    This is the perceived mode a subscriber is used to in fixed broadband networks (e.g. DSL) and a

    precondition to attract users from fixed broadband networks.

    To support a high number of HSDPA users in the code limited downlink the feature F-DPCH

    was introduced in REL-6.

    In the uplink, the limiting factor for supporting a similarly high number of E-DCH users is the

    noise rise. For such a high number of users in the cell it can be assumed that many users are not

    transmitting any user data for some time (e.g. for reading during web browsing or in between

    packets for periodic packet transmission such as VoIP).The corresponding overhead in the noise

    rise caused by maintained control channels will significantly limit the number of users that can

    be efficiently supported.

    As completely releasing dedicated channels during periods of traffic inactivity would cause

    considerable delays for reestablishing data transmission and a corresponding bad user perception,

    this WI is intended to reduce the impact of control channels on uplink noise rise while

    maintaining the connections and allowing a much faster reactivation for temporarily inactive

    users.

    This TR summarizes the work done under the WI "Continuous Connectivity for Packet Data

    Users" by listing technical concepts addressing the objectives of the work item analyzing these

    technical concepts and selecting the best solution (which might be a combination of technical

    concepts).

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    1.2.4. Enhanced CELL_FACH operation

    Some of the biggest drawbacks in UMTS are the availability of less data rate on FACH (Forward

    Access Channel, also known as the common downlink channel) and the delay involved in the

    RRC state transition from common RRC states (Cell_FACH, Cell_PCH & URA_PCH) to

    dedicated RRC state (Cell_DCH).

    To understand these further let us analyze the nature of some of the services that are provided on

    the transport provided by the UMTS Radio Protocols. In "always on" services like PoC (Push-to-

    talk over Cellular), Push e-mail and VPN Connections small packets of data (for example: keep

    alive packets) are transmitted frequently in the background. For such services FACH channels

    cannot be employed because a) the required peak data rate for such services cannot be supported

    by FACH, b) FACH does not support fast power control mechanism that is required for

    supporting high data rates and, c) if several users want to use such services in a cell then

    using FACH channel for so many users is far from ideal. So, instead of using FACH if DCH

    transport channels (which are dedicated to an user) are to be used then it is not preferred for these

    kind of services because it is waste of channel bandwidth and channelization code space.

    To overcome the above deficiencies and to provide a good QoS that results in better end-user

    satisfaction 3GPP has introduced a new feature called "Enhanced Cell_FACH" in Rel-7 UMTS

    specifications that will use the high speed shared channels in RRC states other than Cell_DCH.

    Because high speed shared channels are used in all the connected mode RRC states the name

    "Enhanced Cell_FACH" is a bit of a misnomer in that sense.

    Some of the advantages of using high speed shared channels in the downlink in RRC states other

    than Cell_DCH are:

    HS-DSCH channels that are used in the downlink for achieving high data rates inHSDPA can be used to prop up the available data rate as the network can use Adaptive

    Modulation and Coding scheme to change the transmission parameters depending upon

    the network conditions although at a very slow rate because of unavailability of control

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    channel in the uplink that will report the result of decoding at the UE and the radio

    conditions.

    For the kind of services described above, if HS-DSCH channels are used in the downlinkin all the RRC states then there is no need tear down and establish channels in the

    downlink and its associated signaling.

    In addition to the above the improvements done to high speed shared channels (HS-DSCH) as part of other features like Continuous Packet Connectivity (CPC) can also be

    taken advantage of.

    Therefore, to summarize, some of the main goals of Enhanced Cell_FACH feature are to:

    Increase the data rates in Cell_FACH state Decrease the latency in RRC state switching Better channelization code usage Use of shared channels in the downlink to take advantage of features like CPC and other

    Rel-7 features that use downlink shared channels

    Align the radio protocol architecture of UMTS closer to the architecture used in LTE(Long Term Evolution) i.e. the use of shared channels in the uplink and downlink

    Let us now look at the new mapping for logical channels, transport channels and physicalchannels in the downlink (in the below diagram). The indicator channels like PICH and MICH

    have been intentionally left out.

    Figure1.2: Mapping of Channels

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    CHAPTER-2

    HIGH SPEED PACKET ACCESS

    2.1. Architecture

    Figure2.1: Architecture of HSPA

    GGSN- Gateway GPRS Support Node

    SGSN- Serving GPRS Support Node

    RNC- Radio n/w Controller

    DHCP-Dynamic Host Configuration Protocol

    HSS-Home subscriber server

    PCRF-Policy Control & Charging Rules Function

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    Serving GPRS Support Node (SGSN)

    The SGSN is the most important element of the GPRS network. The SGSN of the GPRS

    network is equivalent to the MSC of the GSM network. There must at least one SGSN in a

    GPRS network. There is a coverage area associated with a SGSN. As the network expands and

    the number of subscribers increases, there may be more than one SGSN in a network. The SGSN

    has the following functions:

    Protocol conversion (for example IP to FR) Ciphering of GPRS data between the MS and SGSN Data compression is used to minimize the size of transmitted data units Authentication of GPRS users Mobility management as the subscriber moves from one area to another, and possibly one

    SGSN to another

    Routing of data to the relevant GGSN when a connection to an external network isrequired

    Interaction with the NSS (that is, MSC/VLR, HLR, EIR) via the SS7 network in order toretrieve subscription information

    Collection of charging data pertaining to the use of GPRS users Traffic statistics collections for network management purposes.

    Gateway GPRS Support Node (GGSN)

    The GGSN is the gateway to external networks. Every connection to a fixed external data

    network has to go through a GGSN. The GGSN acts as the anchor point in a GPRS data

    connection even when the subscriber moves to another SGSN during roaming. The GGSN may

    accept connection request from SGSN that is in another PLMN. Hence, the concept of coverage

    area does not apply to GGSN. There are usually two or more GGSNs in a network for

    redundancy purposes, and they back up each other up in case of failure. The functions of a

    GGSN are given below:

    Routing mobile-destined packets coming from external networks to the relevant SGSN Routing packets originating from a mobile to the correct external network Interfaces to external IP networks and deals with security issues Collects charging data and traffic statistics

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    Allocates dynamic or static IP addresses to mobiles either by itself or with the help of aDHCP or a RADIUS server

    Involved in the establishment of tunnels with the SGSN and with other external networks.

    Domain Name Server (DNS)

    These devices convert IP names into IP addresses, for example, server.nokia.com to 133.44.15.5.

    There is a primary DNS server and a secondary DNS server.

    Dynamic Host Configuration Protocol (DHCP)

    The Dynamic Host Configuration Protocol (DHCP) is a network protocol that is used to

    configure devices which are connected to a network (known as hosts) so that they can

    communicate on an IP network. It involves clients and a server operating in a client-server

    model. In a typical personal home local area network (LAN), a router is the server while clients

    are personal computers or printers. The router receives this information through a modem from

    an internet service provider which also operates DHCP servers where the modems are clients.

    The clients request configuration settings using the DHCP protocol such as an IP address, a

    default route and one or more DNS server addresses. Once the client implements these settings,

    the host is able to communicate on that internet.

    The DHCP server maintains a database of available IP addresses and configuration information.

    When the server receives a request from a client, the DHCP server determines the network to

    which the DHCP client is connected, and then allocates an IP address or prefix that is appropriate

    for the client, and sends configuration information appropriate for that client. DHCP servers

    typically grant IP addresses to clients only for a limited interval. DHCP clients are responsible

    for renewing their IP address before that interval has expired, and must stop using the address

    once the interval has expired, if they have not been able to renew it.

    DHCP is used for IPv4 and IPv6. While both versions serve much the same purpose, the details

    of the protocol for IPv4 and IPv6 are sufficiently different that they may be considered separate

    protocols.

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    Hosts that do not use DHCP for address configuration may still use it to obtain other

    configuration information. Alternatively, IPv6 hosts may use stateless address auto

    configuration. IPv4 hosts may use link-local addressing to achieve limited local connectivity.

    Home Subscriber Server (HSS)

    The Home Subscriber Server (HSS) is the master user database that supports IMS network

    entities that handle calls and sessions. This article explains the way in which a Home Subscriber

    Server can communicate with a Web Logic SIP Server (WLSS). It also discusses the different

    data that a Web Logic SIP Server can retrieve from the HSS and how this data can be updated.

    This article provides a general and technical introduction to the DIAMETER protocol and the Sh

    Interface, and shows the different types of requests that can be used by WLSS to retrieve user

    data for executing a service.

    Policy and Charging Rules Function (PCRF)

    Policy and Charging Rules Function (PCRF) is the software node designated in real-time to

    determine policy rules in a multimedia network. As a policy tool, the PCRF plays a central role

    in next-generation networks. Unlike earlier policy engines that were added on to an existing

    network to enforce policy, the PCRF is a software component that operates at the network core

    and accesses subscriber databases and other specialized functions, such as a charging system, in

    a centralized manner. Because it operates in real time, the PCRF has an increased strategic

    significance and broader potential role than traditional policy engines. This has led to a

    proliferation of PCRF products since 2008.

    The PCRF is the part of the network architecture that aggregates information to and from the

    network, operational support systems, and other sources (such as portals) in real time, supporting

    the creation of rules and then automatically making policy decisions for each subscriber active

    on the network. Such a network might offer multiple services, quality of service (QoS) levels,

    and charging rules. PCRF can provide a network agnostic solution (wire line and wireless) and

    can also enable multi-dimensional approach which helps in creating a lucrative and innovative

    platform for operators. PCRF can also be integrated with different platforms like billing, rating,

    charging, and subscriber database or can also be deployed as a standalone entity.

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    CHAPTER-3

    HIGH SPEED DOWNLINK PACKET ACCESS

    3.1. Introduction

    In downlink a new entity called MAC-hs contains the new HSDPA functionality as seen in

    Figure 1. Instead of a fixed code allocation with fast power control, the code and power resource

    is now shared amongst all active HSDPA users. For this purpose a new transport channel, the

    High Speed Downlink Shared Channel (HS-DSCH), has been defined that supports adaptive

    coding and modulation, whereby every 2ms the transmission format can change dynamically. In

    good radio channel condition 16QAM modulation can be used instead of QPSK and the rate 1/3

    turbo code may be punctured down to enable higher data rates. Depending on the UE capabilitiesup to 15 codes with a fixed spreading factor of 16 can be received if all codes are allocated to a

    single UE. Since power control is replaced by rate control with adaptive coding and modulation

    the maximum data rate as received by the user directly depends on the channel and interference

    conditions as well as the user position in the cell.

    The Node B scheduler must take care that fairness is maintained. The dynamic resource

    allocation by the scheduler (per 2ms TTI) is signaled to the users on a new downlink control

    channel called High Speed Signaling Control Channel (HS-SCCH).

    The following information is carried on the HS-SCCH:

    UE Identity (UE ID) via a UE specific CRC which allows addressing specific UEs on theshared control channel.

    Transport Format and Resource Indicator (TFRI) which identifies the scheduled resourceand its transmission format.

    Hybrid-ARQ-related information to identify redundancy versions for the combiningprocess.

    Each user can monitor up to 4 HS-SCCHs. For the support of channel based scheduling and

    HARQ.

    Following feedback signaling is transmitted on the High Speed Dedicated Physical Control

    Channel (HS-DPCCH) in the uplink:

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    Channel Quality Information (CQI) to inform the scheduler about the instantaneouschannel condition.

    HARQ ACK/NACK information to let the sender know the outcome of the decodingprocess and to request retransmissions.

    Figure 2 depicts the data and signaling flow during HSDPA transmission. Based on the UE

    channel quality report the Node B scheduler sends data on the shared downlink channel to the

    user. The UE will then reply with an ACK or NACK message based on the outcome of the

    decoding. Note that the standard does not specify scheduling and resource allocation which

    leaves significant freedom to Node-B implementations.

    Figure 3.1: Simplified HSDPA transmission scheme

    3.2. Enhanced Uplink Dedicated Channel

    Due to the non-orthogonal uplink transmission in W-CDMA the principles applied for the newly

    defined transport channel Enhanced Dedicated Channel (E-DCH) are fundamentally different

    from HSDPA. The shared resource in the system is the received interference at the Node B and a

    transmission at a single UE can impact the raise over thermal noise as received by different Node

    B. Continuous uplink power control is still an essential means of link adaptation due to the well

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    known near-far problem. Consequently it was decided to support soft handover for E-DCH to

    minimize intercellular interference. Unlike HSDPA the scheduler is not aware of the

    transmission buffer status, channel state and the UE transmission capabilities. Partly this

    information will be signaled to the Node B via control signaling.

    For the support of the new functionality several new physical channels were introduced:

    E-DPDCH: E-DCH Dedicated Physical Data Channel for dedicated uplink datatransmission. During data transmission so-called Scheduling Information such as buffer

    status, data priority and power headroom can be piggybacked.

    E-DPCCH: E-DCH Dedicated Physical Control Channel with the associated control datafor E-DPDCH detection and decoding. For the support of the scheduler there is a Happy

    Bit that informs if the UE has sufficient resources for transmission.

    E-HICH: E-DCH HARQ Acknowledgement Indicator Channel to transmit HARQfeedback information (ACK/NACK)

    E-RGCH: E-DCH Relative Grant Channel to grant dedicated resources (up, down, hold)to a UE

    E-AGCH: E-DCH Absolute Grant Channel is a shared channel that allocates an absoluteresource for one or several UE.

    In Figure 3.2.the E-DCH data and signaling flow is illustrated. Based on the rate request

    (Scheduling Information or Happy Bit) the Node B may respond with a resource allocation via

    the absolute or a relative. The UE will use the grant for data transmission and the Node B will

    acknowledge the received packets.

    The HARQ protocol defined for HSDPA and for E-DCH is based on an n-channel stop-and-wait

    protocol. Since out of sequence delivery is a regular event for this protocol, there is a reordering

    function in place to provide in-sequence delivery to higher layer protocols. Unlike in HSDPA

    this function is contained in a separate sub-layer called MAC-es. MAC-es is located in the RNC

    since E-DCH supports soft handover and the packets can be received by different Node Bs. It

    must also be noted that the ACK/NACK reception is not reliable and there may be unwanted

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    repetitions or even packet losses caused by ACK/NACK misinterpretations at the sender. In that

    case RLC can recover the packets if configured in acknowledged mode (AM).

    Figure 3.2: Simplified E-DCH transmission scheme

    Besides an increase in radio and transport network efficiency for packet based services, HSPA

    improves user perception by significantly increased peak data rates and a reduced overall

    latency. Peak data rates depend on the supported reference classes. Typically the operator will

    upgrade the network successively. The first terminals will be a data cards enabling 1.8 Mbit/s

    peak data rate and 3.6 Mbit/s peak data rate.

    At the final state of HSPA Release 6 deployment a maximum of 14.4 Mbps will be supported in

    the downlink and 5.76 Mbps in the uplink. However it should be emphasized that the peak data

    rates are temporary rates at the physical layer and neglect protocol overhead at the different

    layer. Furthermore an optimistically high channel code rate at the physical layer is assumed.

    HSPA networks are not expected to be deployed before 2007. In terms of end-to-end delay

    significant enhancements can be expected due to fast Node-B HARQ retransmission as well as

    reduced transmission time interval. Fast HARQ by the Node B will save at least two times Iub

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    transmission delay compared to RLC ARQ retransmission. Note that the Iub is susceptible to

    congestion due to missing statistical multiplexing on the low capacity last mile. HARQ uses on

    synchronous ACK/NACK feedback and does not rely on infrequent event based RLC status

    reports. Furthermore the interleaving delay decreases proportionally to the TTI reduction. On the

    other hand the HARQ generally operates at higher block error rate and will thus have a higher

    number of retransmissions.

    In general there is no easy calculation of the system throughput and latency reduction due to

    various functions performed at the different layer. All protocol functions must be modeled

    realistically to take into account the impact of encapsulation, segmentation, retransmission,

    reordering etc. Results will be highly dynamic and depend on the selected scenario and

    parameters. Furthermore the gain for a single link may also not necessarily turn into

    improvement of overall system performance. Simulations on system level considering multiple

    cells and multiple users are well established as means to evaluate system performance in todays

    complex mobile communication systems. Due to the high complexity those simulations are very

    time consuming and generally run offline. Nevertheless, in our research effort Nomor Research

    has implemented a standard compliant UMTS system with the enhanced features of HSPDA and

    E-DCH in our RealNeS platform. The Real-time Network Simulation (RealNeS) tool with our

    HSPA implementation as described above allows applications to be tested live and even provide

    means to perform measurements and parameter reconfigurations in real-time.

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    CHAPTER-4

    HIGH SPEED UPLINK PACKET ACCESS

    4.1. Introduction

    HSUPA uses an uplink enhanced dedicated channel (E-DCH) on which it employs link

    adaptation methods similar to those employed by High-Speed Downlink Packet Access HSDPA,

    namely:

    Shorter Transmission Time Interval enabling faster link adaptation. HARQ (hybrid ARQ) with incremental redundancy making retransmissions more

    effective.

    Similarly to HSDPA, HSUPA uses a packet scheduler, but it operates on a request-grant

    principle where the UEs request a permission to send data and the scheduler decides when and

    how many UEs will be allowed to do so. A request for transmission contains data about the state

    of the transmission buffer and the queue at the UE and its available power margin. However,

    unlike HSDPA, uplink transmissions are not orthogonal to each other.

    In addition to this scheduled mode of transmission the standards also allows a self-initiatedtransmission mode from the UEs, denoted non-scheduled. The non-scheduled mode can, for

    example, be used for VoIP services for which even the reduced TTI and the Node B based

    scheduler will not be able to provide the very short delay time and constant bandwidth required.

    Each MAC-d flow (i.e. QoS flow) is configured to use either scheduled or non-scheduled modes;

    the UE adjusts the data rate for scheduled and non-scheduled flows independently. The

    maximum data rate of each non-scheduled flow is configured at call setup, and typically not

    changed frequently. The power used by the scheduled flows is controlled dynamically by the

    Node B through absolute grant (consisting of an actual value) and relative grant (consisting of a

    single up/down bit) messages.

    At the Physical Layer, HSUPA introduces new channels E-AGCH (Absolute Grant Channel), E-

    RGCH (Relative Grant Channel), F-DPCH (Fractional-DPCH), E-HICH (E-DCH Hybrid ARQ

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    Indicator Channel), E-DPCCH (E-DCH Dedicated Physical Control Channel) and E-DPDCH (E-

    DCH Dedicated Physical Data Channel).

    E-DPDCH is used to carry the E-DCH Transport Channel; and E-DPCCH is used to carry the

    control information associated with the E-DCH.

    4.2. 3G UMTS HSUPA key characteristics

    3G HSUPA brings enhanced performance through the addition of new features that sit on top of

    the existing UMTS / W-CDMA technology.

    The key specification parameters that are introduced by the use of HSPA are:

    Increased data rate: The use of HSUPA is able to provide a significant increase in thedata rate available. It allows peak raw data rates of 5.74 Mbps.

    Lower latency: The use of HSUPA introduces a TTI of 2 ms, although a 10ms TTI wasoriginally used and is still supported.

    Improved system capacity: In order to enable the large number of high data rate users,it has been necessary to ensure that the overall capacity when using HSUPA is higher.

    BPSK modulation: Originally only BPSK modulation that adopted for UMTS wasused. Accordingly it did not support adaptive modulation schemes. Higher ordermodulation was introduced in Release 7 of the 3GPP standards when 64QAM was

    allowed.

    Hybrid ARQ: In order to facilitate the improved performance the Hybrid ARQ(Automatic Repeat request) used for HSDPA is also employed for the uplink, HSUPA.

    Fast Packet Scheduling: In order to reduce latency, fast packet scheduling has beenadopted again for the uplink as for the downlink, although the implementation is slightly

    different.

    With these specification parameters enable HSUPA to complement the performance of HSDPA,

    providing an overall performance improvement for systems incorporating HSPA.

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    4.3. 3G HSUPA basics

    At the core of HSUPA, High Speed Uplink Packet Access are a number of new technologies that

    are very similar to those used with HSDPA. However there are a few fundamental differences

    resulting from the different conditions at either end of the link.

    The uplink in UMTS and HSUPA is non-orthogonal because complete orthogonalitycannot be maintained between all the UEs. As a result there is more interference between

    the uplink transmissions within the same cells.

    The scheduling buffers are located in a single location (Node B) for the downlink,whereas for the uplink they are distributed within several UEs for the uplink. This

    requires the UEs requiring sending buffer information to the scheduler in the NodeB so

    that it can then provide an overall schedule for the data transmission.

    In the downlink, the shared resource is the transmission power. In the uplink, the resourceis limited by the level of interference that can be tolerated and this depends upon the

    transmission power of the multiple UEs.

    High order modulation techniques are able to provide higher data rates for high signallevel links in the downlink. There is not the same advantage in the uplink where as there

    is no need to share channelization codes between users and the channel coding rates are

    therefore lower, although higher order modulation was introduced under Release 7.

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    CHAPTER 5

    APPLICATION OF HSPA

    There are various applications of HSPA:

    Use of higher order modulation: 16QAM is used in the downlink instead of QPSK toenable data to be transmitted at a higher rate. This provides for maximum data rates of 14

    Mbps in the downlink. QPSK is still used in the uplink where data rates of up to 5.8

    Mbps are achieved. The data rates quoted are for raw data rates and do not include

    reductions in actual payload data resulting from the protocol overheads.

    Shorter Transmission Time Interval (TTI): The use of a shorter TTI within 3G HSPAreduces the round trip time and enables improvements in adapting to fast channel

    variations and provides for reductions in latency.

    Use of shared channel transmission: Sharing the resources enables greater levels ofefficiency to be achieved and integrates with IP and packet data concepts.

    Use of link adaptation: By adapting the link it is possible to maximize the channelusage.

    Fast Node B scheduling: The use of fast scheduling within 3G HSPA with adaptivecoding and modulation (only downlink) enables the system to respond to the varying

    radio channel and interference conditions and to accommodate data traffic which tends to

    be "bur sty" in nature.

    Node B based Hybrid ARQ: This enables 3G HSPA to provide reduced retransmissionround trip times and it adds robustness to the system by allowing soft combining of

    retransmissions.

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    CONCLUSION

    Advanced signal processing is needed for HSDPA multimode transmission using high-order

    modulation in frequency selective fading channel. An advanced HSDPA receiver using EPIC isproposed and evaluated by link level simulations in this paper. The simulation results proved that

    using interference suppression can improve the system performance considerably with high order

    modulation. The complexity analysis shows that the proposed HSDPA receiver using EPIC only

    requires around 3 times more complexity than the RAKER for the detection of packet

    transmissions. The performance gains of the proposed receiver vs. transmission data rates are

    further summarized.

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