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HUAWEI TECHNOLOGIES CO., LTD.
www.huawei.com
Huawei Confidential
Security Level:
Introduction to LTE Feature 2.0
ISSMS 4.0
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 2
1. LTE Random Access Algorithm
2. LTE Handover Algorithm
3. LTE Power Control Algorithm
4. LTE ICIC Algorithm
5. LTE Scheduling Algorithm
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 3
Access in LTE
Definition
In LTE system, access refers to the process of establishing a connection from UE
to eNodeB and MME.
Access Procedure Overview
When a UE needs to establish a connection with the network for any purpose (for
example, service request, location update, or paging), the access procedure is
performed. The generic procedure is as follows:
1. The UE performs random access.
2. Signaling connections between the UE and the MME are established. The connections are an
RRC connection and a dedicated S1 connection.
3. If the connection is for the purpose of a service request, the MME will then instruct the
eNodeB to establish an E-RAB. The MME establishes, modifies and releases the bearer
through radio bearer management.
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 4
Access Procedure (Paging) Major Functions
The UE requests to access: the system allocates a random access channel. The result is uplink synchronization and dedicated resources allocated.
Signaling connections contains RRC connection and dedicated S1 connection. RRC connection is established upon the request from the UE. Then, the eNodeB establishes dedicated S1 connection between eNodeB and MME. Once the dedicated S1 connection is established, there is a complete signaling pathway from the UE to the MME.
The E-RAB establishment creates radio bearers. Key connections are SRB2 (NAS signaling) and DRBs (user plane data).
Releasing signaling connections involves releasing both the RRC connection and the dedicated S1 connection. RRC connection release indicates release of the RRC connection and all radio bearers. Release may be triggered by either the eNodeB or the MME.
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Random Access Scenarios
Page 5
Random access is performed in the following 5 scenarios:
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Random Access Types
Page 6
Depending on whether contention is introduced, the random access procedure can be categorized into contention based random access and non-contention-based random access:
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 7
Random Access Procedure
UE eNB
RA Preamble assignment0
Random Access Preamble 1
Random Access Response2
contention-based and non-contention-based. 1) Non-contention 2) Contention
UE eNB
Random Access Preamble1
Random Access Response 2
Scheduled Transmission3
Contention Resolution 4
Major differences between contention and non-contention RA procedures: In contention-based RA, preambles are generated by UEs. Preambles from different UEs may
conflict, and the eNodeB performs contention resolution for UE access. Initial connection uses the contention-based RA procedure.
In non-contention-based RA, the eNodeB allocates preambles to UEs, so there is no conflict between UEs.
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 8
Access – Radio Bearers
Radio bearers are classified
into SRBs and DRBs.
Three SRBs SRB0 carries RRC messages before RRC
connections established. It is transmitted
on CCCH and uses TM at the RLC layer.
SRB1 carries RRC messages and also
carries NAS messages before SRB2 is
established. It is transmitted on DCCH
and uses AM at the RLC layer.
SRB2 carries NAS messages, is
transmitted on DCCH and uses AM on the
RLC layer.
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 9
Complete Access Procedure
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 10
1. LTE Random Access Algorithm
2. LTE Handover Algorithm
3. LTE Power Control Algorithm
4. LTE ICIC Algorithm
5. LTE Scheduling Algorithm
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 11
Handover in LTE
Objectives The eNodeB sends the measurement configuration to a UE, and the UE
performs measurements and completes the handover procedure under the
control of the eNodeB to maintain seamless service.
Triggers for Handover in LTE
Coverage: Coverage-based handover connects a moving UE to the cell with
the best signal quality at any given moment, to guarantee that calls are not
dropped during mobility. (Huawei eRAN2.0 currently supports coverage-
based handover only.) Load: Load-based handover transfers UEs from a heavily loaded or
congested cell to a less loaded cell, to maximize use of system resources.
(Not supported at present) Type of service: Cells which support high speed data services transfer UEs
with only voice services to other RATs. (Not supported at present)
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 12
Types of Handover in LTE
Intra-frequency Handover Handover between two LTE cells on the same frequency. Intra-frequency handovers are triggered by UE measurements. As a UE moves from its serving
cell to a neighboring cell on the same frequency, it detects that signal quality is higher in the
neighboring cell, and this triggers a coverage-based handover.
Inter-frequency Handover Handover between two LTE cells on different frequencies. Inter-frequency measurements are triggered by UE measurements. As a UE moves from its
serving cell to a neighboring cell on a different frequency, when signal quality in the serving cell
drops below a certain threshold, this triggers coverage-based inter-frequency measurements.
Inter-RAT Handover Handover from LTE cells to GSM/WCDMA/TD-SCDMA/CDMA2000 cells. Inter-RAT measurements are triggered by UE measurements. As a UE moves out of the area
covered by the LTE system, when signal quality in the serving cell drops below a certain
threshold, this triggers coverage-based inter-RAT measurements.
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 13
Event-Triggered Reporting in LTE Events
Event A1: Signal quality in the serving cell is above a threshold. When a UE reports that
the serving cell meets the triggering condition, the eNodeB stops inter-frequency or inter-
RAT measurements.
Event A2: Signal quality in the serving cell is below a threshold. When a UE reports that
the serving cell meets the triggering condition, the eNodeB starts inter-frequency or inter-
RAT measurements.
Event A3: Signal quality in intra-frequency neighboring cells is higher than that in the
serving cell. When a UE reports this event, the eNodeB sends an intra-frequency
handover request.
Event A4: Signal quality in inter-frequency neighboring cells is above a threshold. When
a UE reports this event, the eNodeB sends an inter-frequency handover request.
Event B1: Signal quality in inter-RAT neighboring cells is above a threshold. When a UE
reports this event, the eNodeB sends an inter-RAT handover request.
Reporting Event-triggered periodic reporting
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 14
Complete LTE Handover Process Three Phases of Handover
Handover measurement: UEs perform
measurements, which are triggered as
described in the previous slide. Handover decision: Based on
measurement reports from UEs, the
eNodeB decides whether to initiate
handovers. Handover execution: The handover
procedure is executed under the control
of the eNodeB.
Note This presentation uses the common type intra-
frequency handover for example.
Inter-frequency and inter-RAT handover
procedures are similar.
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 15
Coverage-Based Intra-Frequency Handover: Intra-Frequency Measurement
Entering/Leaving Conditions for Event A3 Entering condition:
Leaving condition:
Parameters Mn and Ms are the measurement results of the
neighboring and serving cells, respectively. Ofn and Ofs are the frequency specific offsets for
the neighboring and serving cells, respectively. Ocn and Ocs are the cell specific offsets for the
neighboring and serving cells, respectively. Hys is the hysteresis for event A3. Off is the offset for event A3.
Measurement Quantity
RSRP, RSRQ, or both
Measurement Reporting
Event-triggered periodic reporting
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 16
Coverage-Based Intra-Frequency Handover: Decision and Execution
Decision1. The eNodeB generates a list of candidate cells that meet the condition for event A3
based on UE measurement reports.
2. It then screens the list of candidate cells. Where measurement results are identical,
intra-eNodeB cells are prioritized over inter-eNodeB cells.
Execution The eNodeB triggers a handover to the target cell with the best signal quality.
There are four possible scenarios: Inter-eNodeB intra-MME handover in the presence of X2. Signaling messages and
packet data are transmitted over the X2 interface between the eNodeBs. Inter-eNodeB intra-MME handover in the absence of X2. Signaling messages and
packet data are transmitted over the S1 interface. Inter-eNodeB inter-MME handover in the presence of X2. Signaling messages are
transmitted over the S1 interface and EPC, and packet data is forwarded over the X2
interface. Inter-eNodeB inter-MME handover in the absence of X2. Signaling messages and
packet data are transmitted over the S1 interface and EPC.
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Handover Procedure over X2 Interface
Page 17
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 18
Handover Procedure over S1 Interface
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 19
Handover Procedure over S1 Interface (Cont’d)
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 20
Inter-Cell Intra-eNodeB Handover Procedure
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 21
1. LTE Random Access Algorithm
2. LTE Handover Algorithm
3. LTE Power Control Algorithm
4. LTE ICIC Algorithm
5. LTE Scheduling Algorithm
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 22
Power Control: Function and Purpose
Function LTE power control is used to compensate for path loss on channels and shadow
fading, and reduces inter-cell interference.
Power control is implemented on both the eNodeB and the UE. There are uplink
and downlink power control.
Purposes Maintaining service quality
Reducing interference
Reducing energy consumption
Improving coverage and increasing capacity
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 23
Downlink Power Control
Signals and ChannelsCell-specific reference signal
Synchronization signal
Physical Broadcast Channel (PBCH)
Physical Control Format Indicator Channel (PCFICH)
Physical Downlink Control Channel (PDCCH)
Physical Downlink Shared Channel (PDSCH)
Physical HARQ Indication Channel (PHICH)
Downlink Power Control Policies Fixed power assignment: Users set a fixed power level for reference signal (RS),
synchronization signal, PBCH, and PCFICH, as well as PDCCH and PDSCH,
which carry common cell information. Dynamic power control: Dynamic power control helps meet QoS requirements,
reduce interference, improve cell coverage, and increase cell capacity. It is
applicable to PHICH, as well as PDCCH and PDSCH, which carry UE dedicated
information.
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 24
Downlink PDSCH Power Control The PDSCH uses AMC and HARQ, so there is no strict requirement about PDSCH power control
in protocol. PDSCH power control is classified into power control for dynamic scheduling and for semi-
persistent scheduling. For non-VoIP and hybrid services, with dynamic scheduling, there is
(uniform/non-uniform) power control, or two power levels can be set (with ICIC). VoIP services, with
semi-persistent scheduling, use closed-loop power control.
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 25
Uplink Power Control
Power Control of Uplink Signals and Channels
Sounding reference signal
Physical Random Access Channel (PRACH)
Physical Uplink Shared Channel (PUSCH)
Physical Uplink Control Channel (PUCCH)
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
is the PUSCH transmit power expected by the eNodeB during normal PUSCH demodulation.
Uplink PUSCH Power Control
: the ith uplink subframe
: maximum transmit power of the UE
: number of resource blocks (RBs) allocated to PUSCH, namely PUSCH bandwidth on the ith subframe
: target signal power expected by the eNodeB in the reference transport format (TF) of PUSCH
: power compensation factor
: downlink path loss estimated by the UE, calculated using the measured RSRP and cell-specific RS
: power offset between each MCS and the reference MCS
: adjustment to the PUSCH power at the UE, calculated based on the TPC information in PDCCH
Page 26
)}()()()())((log10,min{)( TFO_PUSCHPUSCH10CMAXPUSCH ifiPLjjPiMPiP
CMAXP
)(PUSCH iM
i
)(O_PUSCH jP
)( j
PL
)(TF i
)(if
)(PUSCH O_NOMINAL_ jP)(O_UE_PUSCH jP
)(PUSCH O_NOMINAL_ jP
is the power offset of the UE relative to , reflecting the impact of UE
category, service type and channel quality on the PUSCH transmit power at the UE.
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
PUSCH Power Control eNB updates Po_nominal according to the IN_own( interference level of
current cell ) and OI(overload information) in open loop power control.
Page 27
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Uplink PUCCH Power Control
: the ith uplink subframe
: maximum transmit power of the UE
: signal power expected by the eNodeB
: downlink path loss estimated by the UE, calculated using the measured RSRP and cell-
specific RS
: determined by the PUCCH format. nCQI is the number of information bits in CQI; nHARQ the
number in HARQ. It reflects the effect of CQI and HARQ bit counts on power.
: effect of the PUCCH transport format on the transmit power.
: adjustment to the PUCCH power at the UE, calculated based on TPC information on
PDCCH
Page 28
CMAXP
i
PL
is the target signal power expected by the eNodeB for the reference transport format.
igFnnhPLPPiP HARQCQI F_PUCCH0_PUCCHCMAXPUCCH ,,min
O_PUCCHP
HARQCQI nnh ,
F_PUCCH ( )F
)(ig
O_UE_PUCCHP
PUCCH O_NOMINAL_P
is the power offset of the UE relative to the cell-level , reflecting the impact of
UE category, service type and channel quality on the PUCCH transmit power at the UE.
PUCCH O_NOMINAL_P
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Uplink PRACH Power Control
: maximum transmit power of the UE
: target power expected by the eNodeB when the PRACH preamble format is 0 and the requirements for
the preamble detection performance are met.
: downlink path loss estimated by the UE, calculated using the measured RSRP and cell-specific RS
: power offset for the current preamble format relative to preamble format 0
: total number of preambles sent by UE during RA process. It cannot exceed the maximum number.
: preamble power ramping step
Page 29
CMAXP
PL
Process Outline
The eNodeB sets the expected receive power for the initial preamble. The UE calculates path loss
based on RS power. The eNodeB sends and to the UE through system information.
The UE calculates the correct RA preamble power. If an RA attempt receives no response, the UE
increases PRACH power by one step for the next attempt.
steppreNPLPPP )1(,min preamble0_preCMAXPRACH
O_preP
preamble
preN
step
PL
O_preP step
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 30
1. LTE Random Access Algorithm
2. LTE Handover Algorithm
3. LTE Power Control Algorithm
4. LTE ICIC Algorithm
5. LTE Scheduling Algorithm
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 31
Inter-Cell Interference Coordination (ICIC) Interference in LTE
Within a single cell, the RBs used by all UEs are orthogonal, so intra-cell interference is negligible.
All cells can use the entire system bandwidth, so inter-cell interference is obvious. In particular,
cell edge users (CEUs) are affected by severe interference from neighboring cells.
Two Solutions to Reduce Inter-Cell Interference IRC: combines receiving antennas to combat strong colored inter-cell interference. It operates at
the physical layer. For details, see the MIMO Feature Parameter Description. ICIC: reduces inter-cell interference by collaborating with scheduling and power control. It
operates at the MAC layer. The principle is that the eNodeB limits the time-frequency and power
resources it can allocate to cell center users (CCUs) and CEUs. CEUs experiencing significant
interference from a neighboring cell are allocated resources orthogonal to that cell, or CEUs are
scheduled at staggered times. In this way, inter-cell interference is minimized, throughput is
increased for CEUs, and coverage is improved.
Types of ICIC Dynamic ICIC and static ICIC: The classification depends on the need for dynamic adjustments of
resources on edge bands. Uplink ICIC and downlink ICIC: are both implemented by the eNodeB.
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 32
Downlink Initial Band Division and Adjustment
Initial Band Division in Downlink Static ICIC A hexagon represents one cell. White is central area. One of three possible ICIC band division schemes is set by
the parameter CELLBANDDIV. Three neighboring cells will
each use a different scheme.
When the cell edge load is high, more edge bandwidth is assigned.
When increasing edge bandwidth, the eNodeB evaluates interference from neighboring
cells and performs interference coordination on the neighboring cells causing greatest
interference.
When the cell edge load is low, the edge bandwidth is reduced.
When reducing edge bandwidth, the eNodeB removes most recently added bandwidth
first.
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 33
UE Type Determination
When UEs access a cell initially, they are CCUs as default. When UEs
access a cell by handover, they are CEUs.
When entering A3 event, that is, the eNodeB receives a measurement report
of RSRP contains both the serving and neighboring cells from this UE, the
UE is treated as a CEU.
When leaving A3 event , that is, the eNodeB receives a measurement report
of RSRP only with the serving cell from this UE, the UE is treated as a
CCU .
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
ICIC Concept
Page 34
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Static Downlink ICIC Procedure
During network planning, the operating band in each cell is divided into an edge
band and a center band. Edge bands in neighboring cells are orthogonal.
Downlink ICIC evaluates cell load and determines whether to block RBs. If some
RBs on the center band are blocked, interference on neighboring cells is reduced.
Based on cell load and RSRP reported by UEs, the eNodeB adjusts UE types.
When UEs access a cell initially , they are CCUs as default. When UEs access a
cell by handover, they are CEUs.
Page 35
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Dynamic Downlink ICIC Procedure
The serving cell adjusts its edge band based on the
following information and informs the scheduler of
the band information: Band division scheme, as in the network plan
Private ICIC messages from neighboring cells
Target cells for ICIC, determined based on cell information
and interference evaluation. The neighboring cell list is
managed based on private messages and RSRP reported
by UEs.
Results of load evaluations Based on load evaluations, DL ICIC determines
whether or not to block RBs. If some RBs on the
center band are blocked, interference effects on
neighboring cells are reduced. Based on the RSRP and evaluated cell load reported
by UEs, the eNodeB adjusts UE types, and
scheduling changes in turn.
Page 36
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Static Uplink ICIC Procedure
During network planning, the uplink operating band in each cell is divided into an edge
band and a center band. Edge bands in neighboring cells are orthogonal. Based on RSRP measurement reports from UEs, the eNodeB divides UEs into CEUs
and CCUs, and informs the scheduler. Neighboring cells continually check themselves for interference. When interference
exceeds the OI threshold, a cell sends an OI message to all neighboring cells. When a
serving cell receives an OI message, it checks its validity and executes the necessary
adjustments.
Page 37
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Dynamic Uplink ICIC Procedure
Based on RSRP measurement reports from UEs, the eNodeB divides UEs into CEUs and
CCUs, and informs the scheduler. The eNodeB maps band division information into HII messages and sends them to
neighboring cells (HII target cells). The eNodeB of the serving cell (HII source cell) then
continually adjusts its edge-band bandwidth according to edge-band load and its
neighboring cell list. Then, the eNodeB informs the scheduler. Neighboring cells continually check themselves for interference. When interference
exceeds the OI threshold, a cell sends an OI message to all neighboring cells. When a
serving cell receives an OI message, it checks its validity and executes the necessary
adjustments.
Page 38
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Intra-eNodeB Time-Domain Uplink ICIC Procedure
For interference coordination between
different cells on a single eNodeB When frequency coordination fails to
resolve high interference Not for TDD mode or handover users
Page 39
Procedure:
Based on RSRP measurement reports from UEs, the eNodeB divides UEs into CEUs and CCUs,
and informs the scheduler.
Neighboring cell list is managed based on RSRP and HII messages. Intra-eNodeB coordination
covers intra-eNodeB cells on the cell-level neighboring cell list.
Neighboring cells continually check themselves for interference. When interference exceeds the OI
threshold, a cell sends an OI message to all neighboring cells. When a serving cell receives an OI
message, it checks its validity and executes the necessary adjustments.
UE types and neighboring cell information are inputs to the scheduler. The scheduler determines
which neighboring cell is causing the interference, and then decides for each CEU to use either odd
or even sub-frames only.
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 40
1. LTE Random Access Algorithm
2. LTE Handover Algorithm
3. LTE Power Control Algorithm
4. LTE ICIC Algorithm
5. LTE Scheduling Algorithm
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 41
What Is Scheduling?
Overview When LTE is using shared channels, time-frequency resources are
dynamically shared. How does the eNodeB allocate resources? Through
scheduling. Scheduling is the process of allocating time-frequency
resources to UEs based on service type, data volume, and channel
quality. Scheduling for both uplink and downlink is completed at the MAC layer.
Objectives The objectives of scheduling are to transmit as much data as possible
over good quality connections and maximize capacity, while also meeting
QoS requirements.
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 42
Concepts about Scheduling
Channel Quality Channel Quality Indicator (CQI). CQI is a downlink quality indicator. CQI is reported by the UEs under
control the of eNodeB. Reports can be periodic, event-triggered, or both.
Signal to Interference plus Noise Ratio (SINR). In downlink scheduling, uplink SINR is the channel quality
indicator. SINR is measured at the physical layer. To make the IBLER for each UE approach the target
IBLER, the eNodeB adjusts SINR based on uplink data ACK/NACK.
QoS
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 43
Scheduling Modes and Policies
Scheduling Modes Dynamic scheduling. The eNodeB makes a scheduling decision every TTI and informs all
UEs to be scheduled. One TTI is 1 ms.
Semi-persistent scheduling. Within a preset semi-persistent scheduling period (20 ms for the
Huawei eNodeB), a single user will use the same time-frequency resources until they are
released. Semi-persistent scheduling is usually used for services with fixed bit rates, periodic
data arrival and small delays, such as VoIP. This type of scheduling can reduces signaling
overhead.
Scheduling Policies Huawei eNodeB supports three basic scheduling policies: Max C/I, Round Robin (RR), and
Proportional Fair (PF). It also supports one enhanced policy: Enhanced PF (EPF).
In the basic policies, all services use dynamic scheduling. In EPF, only VoIP uses semi-
persistent scheduling.
In actual network deployment, EPF is generally used.
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Scheduling types Frequency-selective scheduling. In DL scheduling, frequency-selective
scheduling allocates continuous subcarriers or RBs to UEs. This technology
requires that the eNodeB have detailed channel quality information. Using sub-
band CQIs, the eNodeB finds good quality resources increasing system utilization
and peak speed of UEs. Non-frequency-selective scheduling. In DL scheduling, non-frequency-
selective scheduling allocates discrete subcarriers or RBs to UEs. For this mode,
the eNodeB only needs full band CQIs, so signaling overhead is lower. In UL
scheduling, non-frequency-selective scheduling searches within a band from high
to low for continuous usable RBs. When few UEs need to be scheduled in a cell,
frequency-selective scheduling generates many data fragments. Non-frequency-
selective scheduling is therefore prioritized.
Page 44
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Scheduling _Resource Allocation
Resource Allocation Type: Localized: is propitious to frequency-selective scheduling
Distributed: can bring frequency diversity gain.
PDSCH Resource Allocation Type Resource allocation type 0:Based on RBG, bitmap indicates resource allocation.
Resource allocation type 1:Based on RBG subset, bitmap in subset indicates resource allocation
Couldn’t allocate resource from different RBG subset.
Resource allocation type 2:Virtual RB map to Physical RB;
Including localized VRB and Distributed VRB.
Page 45
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Scheduling _Resource Allocation
Page 46
TYPE 0 : RBG TYPE 1 : RBG Subset
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Scheduling _Resource Allocation TYPE 2 based on RB.
Page 47
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 48
Downlink Scheduling
Overview Downlink scheduling allocates time-frequency resources in PDSCH to system information or
data transmission.
The scheduler measures the remaining power and calculates resources that can be scheduled.
It then decides scheduling priorities and MCS based on the volume of data waiting in the RLC
layer, the QoS requirements for each bearer, and UE channel quality (CQIs reported by UEs).
Procedure Scheduling priorities in descending order: VoIP services, control plane data/IMS signaling
messages, data to be retransmitted, and other initially transmitted data services.
The scheduler uses semi-persistent scheduling for VoIP services and dynamic scheduling for
other data.
Control plane data is second in priority only to VoIP. It is dynamically scheduled. Control plane
data includes common control messages and UE level control messages. The scheduling of
IMS signaling messages is consistent with UE level control message processing (SRB1,
SRB2).
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 49
Uplink Scheduling Overview
Uplink scheduling is the allocation of suitable PUSCH resources to the right UE at the right time.
EPF scheduling is the default.
Uplink scheduling begins after a request by the UE. MCS is selected and a specific number of RBs
are allocated based on the current UE channel quality, volume of data to be scheduled, and power
headroom.
During uplink scheduling, UE channel quality is indicated by SINR measured at the physical layer by
the eNodeB; data volume is reported by the UE in its BSR; power headroom is reported by the UE in
its PHR.
Procedure Scheduling priorities in descending order: VoIP services, control plane data/IMS signaling
messages, data to be retransmitted, and other initially transmitted data services.
The scheduler uses semi-persistent scheduling for VoIP services and dynamic scheduling for other
data.
Control plane data is second in priority only to VoIP. It is dynamically scheduled. Control plane data
includes common control messages and UE level control messages. The scheduling of IMS
signaling messages is consistent with UE level control message processing (SRB1, SRB2).
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