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Revision Record
Course Code ProductProduct Version
Course Version ISSUE
OWA333010 RNC RAN10 Issue 1.11
Developer/Modifier Time Approver New/Update
Liangjie/41026 2009-10-30 Mijia/43064 Update
Liangjie/41026 2009-11-30 Mijia/43064 Update
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Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
HSPA+ Principle
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About This Coursel This course introduces principles and some key
technologies of HSPA+.
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Referencesl 3GPP Release 7 Specification References:
p 3GPP TS 25.211: Physical channels and mapping of transport channels onto physical channels (FDD)
p 3GPP TS 25.212: Multiplexing and channel coding (FDD)
p 3GPP TS 25.213: Spreading and modulation (FDD)
p 3GPP TS 25.214: Physical layer procedures (FDD)
p 3GPP TS 25.308, "UTRA High Speed Downlink Packet Access (HSPDA); Overall description"
p 3GPP TS 25.309: FDD Enhanced Uplink
p 3GPP TS 25.301: Radio Interface Protocol Architecture
p 3GPP TS 25.302: Services provided by the physical layer
p 3GPP TS 25.321: Medium Access Control (MAC) protocol specification
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Contents1. HSPA+ Overview
2. Key Technologies of HSPA+
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Contents1. HSPA+ Overview
2. Key Technologies of HSPA+
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HSPA+ Introductionl HSPA refers to HSDPA and HSUPA which are introduced in
3GPP Release 5 and Release 6. It can provide significant
throughput, latency, and capacity gains on the downlink and
uplink, compared to Release 99.
l HSPA+ (also known as HSPA evolution) is introduced in
3GPP Release 7. It is an enhancement to HSPA.
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Goals for HSPA+ in Release7l Reduced service delay
l Increase peak data rates
l Improve spectrum efficiency
l Increase system capacity
l Reduce UE power consumption
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Room to Improve Release 6
l Release 6 (HSDPA and HSUPA) already provides high-speed wireless access to large number of users.
l But there is room for even more improvements:p Use of multiple antenna techniques (MIMO) to increase peak data rate
and system capacity
p Higher order modulation scheme to improve downlink spectral efficiency and peak data rate
p Adapt system behavior to match application requirements to reduce interference and to extend UE battery life
p Expand use of high speed HS-PDSCH channel beyond DTCH and DCCH, extend it to the CELL_FACH state.
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HSPA+ Features in Release 7
l Downlink enhanced L2
l Downlink 64QAM
l MIMO (Multiple Input Multiple Output)
l Enhanced CELL_FACH operation
l CPC (Continuous Packet Connectivity)
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MIMO and DL 64QAM
l MIMO
p MIMO increases transmission rates through space
multiplexing and improves channel qualities through space
diversity. The network side can dynamically select single- or
dual-stream transmission according to channel conditions. The
peak rate at the MAC layer can reach 28 Mbit/s.
l DL 64QAM
p DL 64QAM allows the use of 64QAM in HSDPA to increase
the number of bits per symbol and thus to obtain higher
transmission rates. The peak rate at the MAC layer can reach
21 Mbit/s.
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Enhanced CELL_FACH Operation
l Enhanced CELL_FACH operation
p Enhanced CELL_FACH operation allows the use of HSDPA
technologies for the UEs in the CELL_FACH, CELL_PCH, and
URA_PCH state. The purpose is to increase the peak rates in
these states and reduce the signaling transmission delay
during service setup or state transition with the result
improving the user experience.
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DL Enhanced L2
l This feature allows Uu L2 to use flexible PDU size on RLC
layer and segmentation on MAC layer. The feature
prevents the L2 from becoming the bottleneck of higher Uu
rate increased by MIMO and 64QAM.
l DL enhanced L2 is the precondition of MIMO, 64QAM and
enhanced CELL_FACH operation.
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CPC (Continuous Packet Connectivity)
l CPC allows the uplink and downlink transmissions to take place at periodic intervals. This feature reduces the transmitted power (and thus increases the UE battery life) because the UE does not have to monitor and transmit overhead channels every TTl. This reduction in the transmitted power also helps to increase the uplink capacity by decreasing the total interference. This improvement is especially significant when there are users who transmit data infrequently as VoIP users.
l CPC feature consists of DL DRX, UL DTX and HS-SCCH less operation.
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HSPA+ Capable UE CategoriesHS-DSCH category
Supported Modulations Without MIMO
Supported Modulations with MIMO
Category 13QPSK, 16QAM, and 64QAM None
Category 14
Category 15QPSK and 16QAM QPSK and 16QAM
Category 16
Category 17QPSK, 16QAM, and 64QAM QPSK and 16QAM
Category 18
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Contents1. HSPA+ Overview
2. Key Technologies of HSPA+
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Contents2. Key Technologies of HSPA+
2.1 Downlink Enhanced L2
2.2 Downlink 64QAM
2.3 MIMO
2.4 Enhanced CELL_FACH Operation
2.5 CPC
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Limitation of Original L2 Functionl MIMO and 64QAM increase the DL rates on the Uu
interface. The original DL L2 function cannot adapt to such
high rates. To prevent L2 from becoming the bottleneck of
network performance, 3GPP Release 7 introduces
enhancements to L2.
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Downlink Enhanced L2 in Release 7l Downlink enhanced L2 includes the following two features:
p Improving the RLC entity to support flexible RLC PDU sizes
p Adding a new entity, the MAC-ehs, implementing data
segmentation at the MAC layer, and supporting the
multiplexing of multiple priority queues
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Flexible RLC PDU sizel With introduction of flexible RLC PDU sizes, the RLC layer
will not segment higher-layer packets with sizes less than
maximum RLC PDU size (the maximum RLC PDU size is
configurable and maximum value is 1500 bytes). Thus, the
RLC layer can flexibly adapt to variations in traffic volume
and reduce the overhead of the RLC PDU header.
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MAC-hs Entity (UTRAN side) in Release 6
MAC-hs
MAC – Control
HS-DSCH
TFRC selection
Priority Queue distribution
Associated Downlink Signalling
Associated Uplink Signalling
MAC-d flows
HARQ entity
Priority Queue distribution
Priority Queue
Priority Queue
Priority Queue
Priority Queue
Scheduling/Priority handling
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MAC-ehs Entity (UTRAN side) in Release 7
MAC-ehs
MAC – Control
HS-DSCH
TFRC selection
Priority Queue distribution
Associated Downlink Signalling
Associated Uplink Signalling
MAC-d flows
Priority Queue
Scheduling/Priority handling
Priority Queue
Priority Queue
Segmentation
Priority Queue MUX
HARQ entity
Segmentation
Segmentation
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Contents2. Key Technologies of HSPA+
2.1 Downlink Enhanced L2
2.2 Downlink 64QAM
2.3 MIMO
2.4 Enhanced CELL_FACH Operation
2.5 CPC
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Modulation Modes for HSPA+l Three modulation modes can be used for HS-PDSCH
64QAM allows more bits per Symbol to be transmitted
Higher peak rate achieved in good channel condition
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CQI Mapping Table Change for 64QAM
CQI TBS Codes Modulation
1 136 1 QPSK…
25 14424 10 16-QAM
26 15776 10 64-QAM
27 21768 12 64-QAM
28 26504 13 64-QAM
29 32264 14 64-QAM64-
l 64QAM configuredl 64QAM not configured
CQI TBS Codes Modulation
1 137 1 QPSK…
25 14411 10 16-QAM
26 17237 12 16-QAM
27 21754 15 16-QAM
28 23370 15 16-QAM
29 24222 15 16-QAM16-
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HS-SCCH Change for 64QAM
Channelization Code Set
Modulation Scheme0: QPSK
1: 16QAM
MUX
HS-SCCH part 1
Channelization Code SetLast bit: 0:16QAMLast bit 1: 64QAM
Modulation Scheme0: QPSK1: QAM
MUX
HS-SCCH part 1
l Release 6 l Release 7
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Prerequisites for Downlink 64QAMl UE capability
p UE category 13, 14, 17 and 18 can support downlink 64QAM.
l Service type
p 64QAM modulation mode is only used for HSPDA service.
l Cell capability
p The Serving cell must support downlink enhanced L2 and 64
QAM.
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Contents2. Key Technologies of HSPA+
2.1 Downlink Enhanced L2
2.2 Downlink 64QAM
2.3 MIMO
2.4 Enhanced CELL_FACH Operation
2.5 CPC
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What is MIMO?l MIMO: Multiple Input Multiple Output
Transmitter ReceiverWireless Channel
… …
N M
Channel Condition Feedback
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What can MIMO provide?l 2×2 MIMO can increase peak data rate to 28Mbps
Transmitter ReceiverWireless Channel
Channel Condition Feedback
Data Stream 1
Data Stream 1
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Effect of Channel Condition to MIMO
l MIMO operation is affected by channel condition of UE.
l Only when the channel conditions are good, two parallel
data streams can be carried in different transmitters. This is
dual-stream case. Otherwise only one data stream is carried
even though two transmitters are used. This is single-
stream case.
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HSDPA with MIMO in Release 7l Operation is similar to Release 5 HSDPA, but with different signaling:
p Via HS-DPCCH UE reports
n Channel Condition
n Preferred antenna weight
n Dual stream or single stream preference
p Based on UE report, NodeB
n Determines number of data streams, TB size, modulation and coding scheme and antenna weighting
n Informs UE of the decision via HS-SCCH
l NodeB transmits the data via HS-PDSCH channel.
l Upon receiving the data, UE sends ACK/NACK via HS-DPCCH.
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Illustration of 2× 2 MIMO
Pre-coding
Pilot for channel estimation
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Pre-codingl In single-stream case pre-coding is used to achieve
transmit diversity. It is similar to closed-loop transmit diversity.
l In dual-stream case pre-coding is used to reduce the interference between two streams and try to make them orthogonal.
l Four predefined antenna weighting vectors are used, identified by PCI (Pre-coding Indicator). NodeB decides which weighting vector is used and inform UE.
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Pilots for Channel Estimationl On each antenna, a common pilot channel is transmitted.
It is used to estimate the channels between NodeB and UE.
l In 2×2 MIMO mode the channel between transmitter and receiver can be expressed as the following format, where hi,j is the estimate of the channel between the physical antenna i at the base station and the antenna j at the UE.
=
2,2
2,1
1,2
1,1
hh
hh
H
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HS-DPCCH Signalingl UE reports on HS-DPCCH
p Preferred number of transport blocksn 2 TBs = dual stream transmission
n 1 TBs = single stream transmission
p Channel Quality Indicator (CQI)n Type A: provide CQI for each TB when 2 TBs are preferred
n Type B: provide CQI when only one TB should be sent
p Preferred pre-coding (Pre-coding Control Indication: PCI)n Indicate 1 of 4 predefined pre-coding vectors
p ACK/NACKn If one TB was transmitted, UE sends one ACK or NACK
n If two TBs were transmitted, UE reports one out of four possible values for ACK/ACK, ACK/NACK, NACK/ACK, NACK/NACK
n Each TB is acknowledged independently.
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Two Types of CQI Feedbackl Two types of CQI is reported by UE: type A and type B
l In type A report, UE indicates:
p Preferred pre-coding vectors (2 bits)
p Preferred number of TBs per TTI
p CQI (8 bits)
n “Old” 31-level CQI report, if one TB is preferred
n “New” 255-level CQI report, if two TBs is preferred
l In type B report, UE indicates:
p Preferred pre-coding vectors (2 bits)
p CQI (5 bits)
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Two Types of CQI Feedback (continued)
Type A Type A Type A Type A Type B Type A Type A Type A Type BType A Time
Configurtion N/M = 4/5, CQI feedback cycle = 1 (2ms)
Type A Type A Type B Time
Configuration N/M = 2/3, CQI feedback cycle = 4 (8ms)
l NodeB Configures UE to use N type A reports every period
of M CQI reports. UE uses type B in remaining time.
l The following are two examples for type A/B reporting:
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HS-SCCH Signaling – Part 1l New HS-SCCH format Part 1
p Transmitted in the first slot of the 3-slot HS-SCCH TTI
p Supports single stream (8 bits) or dual streams (12bits)
p For dual stream operation (12 bits)
n Channelization code set (7 bits)
n Modulation Scheme and number of TBs (3 bits)
n Pre-coding vector (2 bits)
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HS-SCCH Signaling – Part 2l Transmitted in the second and third slots of the HS-SCCH
TTI
l Supports single stream (12 bits) or dual stream (20 bits)
l For dual stream transmission (20 bits):
p Transport block size (6 bits per TB)
p HARQ IDs (4bits)
p Redundancy version (2 bits per TB)
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Prerequisites for MIMOl UE capability
p UE category 15, 16, 17, 18, 19 and 20 can MIMO
l Service type
p MIMO modulation mode is only used for HSPDA service.
l Cell capability
p The Serving cell must support downlink enhanced L2 and
MIMO.
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Contents2. Key Technologies of HSPA+
2.1 Downlink Enhanced L2
2.2 Downlink 64QAM
2.3 MIMO
2.4 Enhanced CELL_FACH Operation
2.5 CPC
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Purpose of Enhanced CELL_FACH Operationl The RRC states of a UE in connected mode include
CELL_DCH, CELL_FACH, CELL_PCH, and URA_PCH. HSPA significantly increases the maximum achievable uplink and downlink data rates, but only for UEs in CELL_DCH states.
l The purpose of the Enhanced CELL_FACH feature is to extend the use of HSDPA function to the CELL_FACH, CELL_PCH, and URA_PCH state as well, allowing a more flexible allocation of resources, increased data rates, and reduced transmission delays. So far RAN11 only supports HSDPA in CELL_FACH.
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Benefits of Enhanced CELL_FACH Operationl UE can reduce the state transitions from CELL_FACH to
CELL_DCH
l UE can receive high speed downlink traffic (data or
signaling) in CELL_FACH.
l UL transmission is still possible in CELL_FACH and uplink
traffic (data or signaling) is carried on RACH. (as in Release
6)
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Logical Channel Mapping in Enhanced CELL_FACH
DTCH BCCHDCCH CCCH
FACH HS-DSCH
RAN10 RAN11
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UE Reception in Enhanced CELL_FACHl UE can decode HS-SCCH using:
p Dedicated H-RNTI (from prior dedicated RRC signaling)
p Or an H-RNTI selected from list of common H-RNTI in SIB5
l UE use HS-SCCH channelization code from SIB5.
l UE decodes HS-PDSCH to receive DL data transmissions.
p BCCH/CCCH/DTCH/DCCH
l No Uplink ACK/NACK or CQI is transmitted.
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State Transition – Idle to CELL_FACH/CELL_DCHl UE procedures in state transition from idle to CELL_FACH/CELL_DCH
1. Read system information in SIB5
2. Sends an RRC Connection Request on PRACH to request PS service
3. Selects an H-RNTI from common H-RNTI listed, HS-SCCH channelization
code from SIB5.
4. Monitor HS-SCCH using selected common H-RNTI.
n Decode HS-PDSCH to receive RRC Connection Setup.
5. Transitions to CELL_FACH or CELL_DCH based on the reconfiguration
message.
n Uses new assigned H-RNTI for further HS-PDSCH reception.
6. May receive subsequent data in CELL_FACH or CELL_DCH
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Contents2. Key Technologies of HSPA+
2.1 Downlink Enhanced L2
2.2 Downlink 64QAM
2.3 MIMO
2.4 Enhanced CELL_FACH Operation
2.5 CPC
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CPC Motivation
l CPC allows packet data users to remain in CELL_DCH
state to a larger extent, thus avoiding frequent packet
connection re-establishments.
l CPC motivation is mainly to allow more efficient use of
continuous packet data connections:
p Higher capacity
p Lower UE battery consumption
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What is CPC?
l CPC adds three main features:
p UL DTX (discontinuous uplink transmission)
p DL DRX (discontinuous downlink reception)
p HS-SCCH less operation
l These three features are optional
p UL DTX can be used alone or in combination with other CPC features.
p DL DRX can be used only if UL DTX is used.
p HS-SCCH less operation can be used alone or in combination with other CPC features.
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Preconditions for CPC Configuration
l UE is in CELL_DCH state.
l No DCH is configured.
l Downlink traffic is carried by HS-DSCH and uplink traffic is
carried by E-DCH.
l SRB (Signaling radio bearer) is carried by HSPA.
l F-DPCH is configured.
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Basic Concepts of UL DTX
l UL DTX includes the following features:
p UL DPCCH DTX
p E-DCH transmission restriction
p CQI reporting DTX
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UL DPCCH DTX
Release 6 UL DPCCH
Release 7 UL DPCCH DTX
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UL DPCCH DTX Activation/Deactivationl UL DPCCH DTX activation and deactivation
DTX at UE_DTX_cycle_1 (Initial state)
DTX at UE_DTX_cycle_2
UL DTX Configured in
RRC?
UL DTX enabled UL DTXdeactivated
UL DTX Active
DTX activationorder
DTX deactivationorder
Data to transmit
No E-DCH data for Inactivity_threshold_for_UE_DTX_cycle_2 TTIs
No UL DTX
Enabling_delayelapse
N
Y
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UL DPCCH DTX Operation
l When UL DTX is active:
p UE shall transmit the uplink DPCCH in a slot if there is:
n HARQ-ACK/NACK transmission on HS-DPCCH
n CQI transmission on HS-PDSCH
n E-DCH transmission
p Otherwise, UL DPCCH shall be transmitted based on:
n Two periodic (DTX_cycle) transmission gaps
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UL DPCCH DTX Operation (continued)
l Two cycles of UL DPCCH DTX
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CQI Reporting DTX
l CQI reporting DTX
UE_DTX_cycle
CQI DTX timerLast HS-DSCH activity on the
downlink
CQI DTX timer expires
CQI feedback cycleNormal CQI reporting Does not coincide with UE_DTX_cycle
No CQI reporting
DPCCH additional transmissions(When CQI is transmitted)
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E-DCH transmission restriction
l UL DTX supports configurable E-DCH transmission start
time restrictions
p It can enable DRX at NodeB to save NodeB processing power.
MAC_Inactivity_ThresholdMAC_DTX_cycle
After data inactivity, UE shall wait nextMAC_DTX_cycle for sending E-DCH data
E-DCH data to sendbut not sent
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Basic Concepts of DL DRX
l DL DRX feature is designed to save UE battery.
l If UL DTX is configured, RNC can also configure DL DRX.
p UE can receive the following channels discontinuously:
n HS-SCCH and HS-PDSCH
n E-AGCH and E-RGCH
p When DRX is configured, RNC will send DL data (on HS-
SCCH and HS-PDSCH) only at pre-defined periodic intervals.
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DL DRX Activation/Deactivation
l DL DRX activation and deactivation
NO DRX (Initial state)
DRX at UE_DRX_cycle
UL DTX and DL DRX
Configured inRRC?
DTX/DRX enabled DL DRXdeactivated
DL DRX Active
DRX activationorder
DRX deactivationorder
No HS-SCCH/HS-PDSCH reception during Inactivity_threshold_for_UE_DRX_cycle subframesNo DL DRX
Enabling_delayelapse
N
Y
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DL DRX Operation
l If DL DRX (and UL DTX) is configured and supported by
UE:
p UE shall continue to receive F-DPCH and E-HICH as
normal operation.
p UE can apply DRX to HS-SCCH and HS-PDSCH.
n If UE has not received an HS-SCCH or HS-PDSCH subframes
during the last Inactivity_Threshlod_for_UE_DRX_cycle
subframes, UE shall monitor HS-SCCH and HS-PDSCH every
DRX_cycle frames.
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DL DRX Operation (continued)
subframe subframe subframe subframe subframe subframe subframe subframesubframe
subframe subframe subframe subframe subframe subframe subframe subframesubframe
HS-SCCH
HS-PDSCH
Inactivity_threshold_for_UE_DRX_cycle UE_DRX_cycle
UE shall monitor continuously HS-SCCH/HS-PDSCH UE shall monitor HS-SCCH/HS-
PDSCH every UE_DRX_cycle only
UE doesn’t monitor HS-SCCH/HS-PDSCH
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E-AGCH and E-RGCH Monitoringl UE can apply DRX to E-AGCH and E-RGCH
p There are two main RRC parameters to control E-AGCH and E-RGCH
DRX: Inactivity_Threshold_for_UE_Grant_Monitoring and
UE_DRX_Grant_Monitoring.
l UE can avoid monitoring E-AGCH and E-RGCH channels except for
the following case:
p A scheduled E-DCH transmission has been performed in any of
Inactivity_Threshold_for_UE_Grant_Monitoring previous TTIs.
p UE_DRX_Grant_Monitoring is TRUE and the start of E-AGCH or E-
AGCH transmission overlaps with an HS-SCCH subframe.
p E-AGCH and E-RGCH commands overlap with an E-HICH
corresponding to a scheduled E-DCH transmission.
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Basic Concepts of HS-SCCH Less Operationl Under certain conditions (for example low data rate), HS-
PDSCH (only for first transmission) can carry data without
associated HS-SCCH.
l With HS-SCCH less operation, DL OVSF codes and power
can be saved for low data rate downlink transmission.
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HS-SCCH Less Operation
l If HS-SCCH less operation is configured by RRC, UE shall
behave as follows:
p UE monitors one or two pre-assigned HS-PDSCH codes
every TTI
n HS-PDSCH CRC is generated based on UE specific H-RNTI.
p UE performs a blind decoding of HS-PDSCH, trying some
predefined transport block sizes.
p The modulation mode can only be QPSK.
n Suitable for low data rate transmission
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HS-SCCH Less Operation (continued)
blind decoding
NACK ACKNACK not transmitted
first transmission first retransmission second retransmission
HS-DPSCH
HS-DPCCH
HS-SCCH
HS-SCCH carries •Pointer to previous transmission•Retransmission number•Transport format•Channelization codes for HS-PDSCH
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CPC Coexistence with Other HSPA+ Features
Feature UL DTX DL DRX HS-SCCH less
UL DTX N/A Compulsory Possible
DL DRX Possible N/A Possible
HS-SCCH less Possible Possible N/A
HSDPA Compulsory Compulsory Compulsory
HSUPA Compulsory Compulsory Possible
F-DPCH Compulsory Compulsory Compulsory
MIMO Possible Possible Not supported
DL 64 QAM Possible Possible No supported
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