1 harmonization meeting on 3gpp hsdpa and 3gpp2 1xev-dv work new-jersey 13-14 nov 2001 hsdpa...
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
HSDPA presentation
3GPP TSG RAN WG2 Chairman, Nortel Networks
3GPP TSG RAN WG1 Chairman, Nokia
HSDPA rapporteur, Motorola
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
• Introduction• Overall architecture and principles• Radio interface aspects• Physical layer aspects• Future activities
Content
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
• Introduction• Overall architecture and principles• Radio interface aspects• Physical layer aspects• Future activities
Content
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
HSDPA objectives
• Increased packet data support– Increase maximum user throughput for downlink packet data (streaming,
interactive and background services)– Lower packet delay
• Compatibility– Evolutionary philosophy – HSDPA architecture is a straightforward enhancement to the R99
architecture • addition of a repetition entity at the Node B below release 99 MAC
layer– All R99 techniques can also be supported in a network supporting HSDPA– Mobiles with HSDPA capability can co-exist with R99 mobiles on the
same carrier
• Standardisation of all interfaces– Including Iur/Iub interfaces
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
HSDPA operation
Node B is enhanced to handle:
• HARQ Retransmissions
• Modulation/coding selection
• Packet data scheduling
Data packets
Data packet
+ possible retransmissions
ACK/NACK
+ TPC commands
+ feedback
Node BRNC
HSDPA capable UE
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
HSDPA Performance• Study in year 2000 (Release 4) indicated a
doubling of capacity compared to Rel'99– Dependant on assumptions, such as scheduler
and cell isolation
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
• Introduction• Overall architecture and principles• Radio interface aspects• Physical layer aspects• Future activities
Content
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
Key additions to R99
• Adaptive Modulation • Hybrid ARQ• Scheduling/repetition at Node B• Shorter radio frame
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
Release 99 DSCH architecture
L2
L1
DSCH
FP
RLC
L2
L1
L2
L1
L2
L1
DSCH
FP
Iub Iur
PHY
MAC
PHY
RLC
Uu
DSCH
FP
DSCH
FP
MAC-c/sh
MAC-D
UE Node B DRNC SRNC
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
Release 5 HS-DSCH Architecture
L2
L1
HS- DSCH
FP
RLC
L2
L1
L2
L1
L2
L1
HS-DSCH
FP
Iub Iur
PHY
MAC
PHY
RLC
Uu
MAC HS-
DSCH
HS- DSCH
FP
HS-DSCH
FP
MAC-c/sh
MAC-D
Optional Entities
UE Node B DRNC SRNC
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
HSDPA in UTRAN architecture
• HSDPA introduction– Compatible with all transport options (AAL2
and IP)– Minor impact on network architecture
• No Impact on RLC• New RRC parameters• No impact on mobility• UTRAN functional hierarchy still valid
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
MAC-HS
• New MAC-HS entity in the Node B– Two sub-entities – one for scheduling and one for HARQ– Permits fast, adaptive scheduling to leverage AMC and
HARQ techniques, thus enabling higher peak data rates– Includes common scheduling/priority handling function
as in R99 MAC-c/sh– Provides HARQ functionality– HARQ round trip optimized to keep soft memory
requirements at UE to a minimum– Reduces delay for successful decoding of packet
compared to RNC based architecture
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
HS-DSCH Transport Channel
• Similar attributes as R99 DSCH, with the following modifications– Shorter fixed TTI value (frame size) of 2 ms– One transport block (data block) per TTI– Fixed length CRC (24 bits) per data block– Dynamic modulation– Rate 1/3 Turbo coding
• Effective code rate achieved with rate matching• Dynamic redundancy version
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
• Introduction• Overall architecture and principles• Radio interface aspects• Physical layer aspects• Future activities
Content
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
UTRAN MAC Architecture
HS-DSCH HS-DSCH
Associated Uplink Signalling
Associated Downlink Signalling
FACH RACH
DCCH DTCH DTCH
DSCH
MAC Control
Iur or local
MAC Control
DCH DCH
MAC-d
USCH TDD only
MAC-c/sh
CPCH FDD only
CCCH CTCH BCCH SHCCH TDD only
PCCH
FACH PCH USCH TDD only
DSCH Iub
MAC Control
MAC-hs
Configuration B
Configuration A
Configuration A
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
MAC-HS-DSCH – UTRAN side
MAC-hs
MAC – Control
HS-DSCH
TFC selection
HS-DSCH
Flow Control MAC-hs / MAC-c/sh or MAC-hs / MAC-d
Associated Downlink Signalling
Associated Uplink Signalling
to MAC-c/sh or MAC-d
HARQ HARQ
Scheduling/Priority Handling
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
MAC-HS-DSCH – UE side
MAC-hs
MAC – Control
Associated Uplink Signalling
To MAC-c/sh
Associated Downlink Signalling
HS-DSCH HS-DSCH
HARQ
Reordering Reordering
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
HARQ Protocol Details
• Asynchronous DL (retransmission can be scheduled independently of occurrence of first transmission)
• Synchronous UL (ACK/NACK timing fixed with respect to downlink transmission)
• Multiple parallel HARQ processes per UE• HARQ processes are common to all HS-DSCH
– Selection of HS-DSCH by HARQ process at first transmission
• Scheduler can abort process at any time• One process can transmit at a time• Multiple priority queues
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
HARQ Protocol cont’d
• Out-of-band (i.e. not on HS-DSCH) signaling supports all HARQ functionality in terms of combining, abort etc.
• In-band (i.e. on HS-DSCH) signaling provides for priority based release of in-sequence PDUs to upper layers at receiver
• In-band signaling provides for re-ordering function at receiver
• Timer based mechanism provides for release of out-of-sequence data blocks– Other mechanisms may be added
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
Physical Layer Functionality
• Transmission of HS-DSCH transport blocks (MAC-hs PDUs)
• DL associated signaling– Scheduling information– HARQ process information– Physical layer information
• UL associated signaling– ACK/NACK– Scheduling assistance indicator
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
DL Signalling
• Two-step approach– Indication of a HS-DSCH transmission provided on
dedicated channel to UE– UE then decodes associated shared control channel– UE finally decodes HS-DSCH
• UE monitors up to four shared control channels• Shared control channels provide information on
transport format and resources for decoding as well as HARQ information (redundancy version, etc.)
• HARQ information and TF information are time-multiplexed to reduce needed processing time
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
DL Physical layer model
PHY
HARQ coding, multiplexing and modulation
HS-DSCH
HARQ info and scheduling info signaling
Phy CH Phy CH Phy CH
PHY
HARQ decoding, de-multiplexing, and demodulation
HS-DSCH
HARQ info and scheduling info signaling
Phy CH Phy CH
Phy CH
UTRAN UE
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
UL Physical Channel Model
PHY
decoding, de-multiplexing,and demodulation
HS-DSCH
HARQ feedback and schedulingassistance information
Phy CHPhy CH
DCH
PHY
coding, multiplexing, andmodulation
HS-DSCH
HARQ feedback and schedulingassistance information
Phy CHPhy CH
DCH
UTRAN UE
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
Hybrid ARQ with HSDPA
• Fast Hybrid ARQ (Retransmission controlled at Node B ->) Less round trip delay
• Combining of the retransmission and first transmission at UE– Node B terminated ARQ protocol means reasonable
terminal memory requirements– Both identical (Chase combining) and non-identical
(Incremental redundancy) retransmissions allowed• terminal memory capability definition based on the
identical retransmissions -> maximum data rate assumes identical retransmissions, lower rates possible also with non-identical retransmissions (Incremental Redundancy)
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
HSDPA Operation Principle
2 ms
ACK/NACK
DataData
PilotPilot
TFCITFCI
TPCTPC
PilotPilot
TFCITFCI
TPCTPC
PilotPilot
TFCITFCI
TPCTPC
DataData
DataData
DataData
PilotPilot
TFCITFCI
TPCTPC
PilotPilot
TFCITFCI
TPCTPC
PilotPilot
TFCITFCI
TPCTPC
DataData
DataData
DataData
PilotPilot
TFCITFCI
TPCTPC
PilotPilot
TFCITFCI
TPCTPC
PilotPilot
TFCITFCI
TPCTPC
DataData
DataData
Uplink DCH
Downlink DCH
PilotData Data PilotData Data PilotData Data PilotData Data PilotData Data PilotData Data PilotData Data PilotData Data PilotData Data
HS-SCCH
HS-DSCH
Demodulation Control
Note: Timing from data to ACK/NACK under discussion!
ACK/NACK after data decoding
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
HSDPA Operation
• Several users can be code multiplexed together • This allows better granularity than with time
multiplexing only and takes terminal capability into account (all terminals are not going to be 10.8 Mcps terminals!)
• Node B has information of the transmission power for each terminal (Power control commands from the terminal) + ACK/NACK feedback info in the uplink
• The number of codes used for HSDPA can vary dynamically between 1 and 15, terminals expected to have varying code handling capability as in Rel'99/Rel'4.
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
• Introduction• Overall architecture and principles• Radio interface aspects• Physical layer aspects• Future activities
Content
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
DL Physical Layer
• HS-PDSCH – fixed spreading factor = 16 (all channelization codes with same scrambling code)
• HS-DSCH has frame length (TTI) of 2 ms (3 slots)– Note this is valid for FDD only– For TDD slightly different principles are used with TTI
definition
• HS-SCCH – shared control channel – SF=128 or 256 (under study)
• UE can be assigned multiple physical channels based on its capability
• Code division multiplexing of UEs within one TTI is allowed
• QPSK and 16-QAM allowed
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
DL Channel Timing
• Associated dedicated channel carrying allocation indication on one slot– Insertion of an indicator by puncturing the data part
(DPDCH) of the physical channel• Shared control channel and Physical shared data channel
have a one slot overlap (HS-PDSCH codes to receive + modulation indication in the first timeslot)
• Transport Format (time critical) and CRC+HARQ information time multiplexed to reduce needed processing time
– HARQ information and TF information are time-multiplexed (The channelisation codes & modulation to be used delivered on the control channel before the data part transmission starts)
• Target round trip of 12 ms
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
UE DL operation
– Maximum 4 HS-DSCH Shared Control Channels that a single UE is monitoring
• Network can configure 1 to 4 to UE (more can be used at cell level)
• Good performance assuming reasonable terminal complexity.
– With continuous activity terminal is able to listen only one control channel.
– The terminal memory requirement shall be derived based on Chase (soft) combining i.e. at max data rate (as given by terminal capability) only Chase combining can be used.
• Network partitions UE memory to various HARQ processes
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
UL Physical Layer for UL signaling
• New Physical channel SF=256 code multiplexed with current dedicated uplink physical channels
• ACK/NACK and Feedback time multiplexed– 1 slot ACK/NACK (or DTX)
• synchronous to DL HS-DSCH timing
– 2 slots either DTX or explicit feedback• Indication of downlink transmissions compatible with
target BLER
Channel Codern bits 20 coded bits
over 2 slots
10 bits/slot
Repeat1 bit 10 bits
On one slot
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
Physical layer timing
Shared control channel, split in 2 parts
HS-DSCH
TTI = 3slots
T DL_control=5slots
HI
Spreading codes, modulation
Parameters
FHARQ parameters, CRC etc...
AssociatedDPCH
Unsynchronisedtiming of UEs:within 1 slot
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
Modulation Aspects
• Both QPSK (as in Rel'99) and 16QAM are defined
• All terminals with HSDPA capability shall support also 16QAM.
• 8PSK & 64QAM were agreed not to be part of HSDPA Rel'5
1011 1001 0001 0011
1010 1000 0000 0010
111 0 11 00 0100 011 0
1111 11 01 0101 0111
i2 i2
i1
q 1
q 2
q 2
0 .3 1 6 2 0 .9 4 8 7
0.31
620.
9487
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
Channel coding
• Rel'99 rate 1/3 Turbo coding is used, other effective coding rates e.g. 1/4, are created with rate matching
• Hybrid ARQ repetitions do not have to be identical in Layer 1, i.e. Incremental Redundancy (IR) can be used
• Channel coding chain is simplified due:
– Only one TrCh per TTI– Only 1 interleaving step– No radio frame segmentation
needed– No DTX during the TTI
TrBlk concatenation
CRC attachment
Code block segmentation
Channel Coding
Rate matching /Incremental Redundancy blk
Physical channelsegmentation
Interleaving
Physical channel mapping
PhCH#1 PhCH#2
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
HSDPA Data Rates (Peak)
• Modulation method QPSK, 16QAM and potentially also 64 QAM– Currently 64 QAM not in Release 5– 10.8 Mbps achievable with 15 codes and 16QAM.
• Coding rates 1/4-3/4 (Rel'99 Turbo Encoder + rate matching)• Spreading factor 16 used in above table
Chip Rate = 3.84 McpsFrame Size = 3 slots
Modulation 10 codes Turbo coding rateInfo Rate(Mbps)
Info bits perframe
64QAM 10.8000 21600 3/416QAM 7.2000 14400 3/416QAM 4.8000 9600 1/2QPSK 2.4000 4800 1/2QPSK 1.2000 2400 1/4
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
UE Capability
• The following parameters characterize a HSDPA terminal capability:
• Maximum number of Transport channel bits per HS-DSCH TTI
• Maximum number of soft channel bits over all HARQ processes
• Number of channelization codes (or, equivalently, number of channel modulation symbols per TTI)
• Minimum inter-TTI interval (to be considered when defining lower capability UE classes)
– Allowed combinations to be defined so as to reduce number of cases
– QPSK and 16 QAM are mandatory for HSDPA capable terminals
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
• Introduction• Overall architecture and principles• Radio interface aspects• Physical layer aspects• Future enhancements
Content
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
Examples of future items
• More modulations• MIMO• Multiple simultaneous receptions in
terminal• New associated DPCH structure
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
Evolution
• HSDPA is part of UTRAN release 5, and will be improved along with the other UTRAN features
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
Back-up slides
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
Adaptive Modulation
• Higher order modulation provides higher peak data rates in favorable channel conditions.
• Gives the flexibility to match Modulation Coding Scheme to the average channel conditions for each user– Provides coarse data rate selection
• Extends the system’s ability to adapt to good channel conditions beyond the use of SF alone.
• But:– Is sensitive to measurement error and delay. H-ARQ can
enable further adaptation
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
Hybrid-ARQ
• Hybrid ARQ combines initial transmission with repetitions in the physical layer to provide higher decoding probability.
• It automatically adapts to instantaneous channel conditions by adding redundancy only when needed– Insensitive to measurement error and delay– Allows fine data rate adjustment– Independent of various thresholds when combined with
AMC
• Enabled by instantiation of Parallel Hybrid ARQ processes
• Fast uplink feedback channel
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
Scheduling/repetition at Node B
• Scheduling at the Node B lowers the delay for critical channel state information– Needed to exploit Adaptive Modulation and
HARQ to their maximum potential– Scheduler can better adapt modulation and
coding to match current channel conditions and fading environment
– Can exploit multi-user diversity by scheduling users in constructive fades
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
Radio frame size
• Shorter “frame size” reduces payload to manageable level– Provides fast feedback mechanism– Lower delay– Best leverages scheduling on constructive
fades – Benefits primarily for hybrid ARQ– Enables maximum utilization of excess power
for data services (i.e. reduced need for power control margin)
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Harmonization Meeting on 3GPP HSDPA and 3GPP2 1xEV-DV Work New-Jersey 13-14 Nov 2001
Feedback channel in uplink
• Fast feedback channel in uplink pairing the HS-DSCH– Fast status for HARQ re-transmission– Channel condition feedback to MAC-hs for
scheduling