1 © Nokia Siemens Networks Presentation / Author / Date For internal use HSDPA High Speed Downlink Packet Access
1 © Nokia Siemens Networks Presentation / Author / DateFor internal use
HSDPA High Speed Downlink Packet Access
Agenda
-> Introduction
General Principal
• HSDPA Key Characteristics, New Features
Architectural Changes, Impact on RAN
Link Adaptation
HSDPA Channel Structure
HARQ Principle
HSDPA – Operating Principle
Packet Scheduling
HSDPA Mobility
What is HSDPA ?
High Speed Downlink Packet Access (HSDPA) is a packet swithed DL data service in WCDMA with data rate up to 10Mbps over a 5MHz Bandwidth
3GPP Rel5 specifications
Builds on distributed architecture that gives Node-B more control when to transmit, to which terminal to transmit and also to handle the retransmission
Nokia RAN05 feature
Improvements and new functionalities coming in RAN05.1 and in RAN06
Why HSDPA?
Improved
• cell throughput
• maximum user throughput
• round trip time
• spectral efficiency
HSDPA Peak Data Rates
5 codes QPSK 1.6 Mbps
# of codes Modulation Max RLC data rate
5 codes 16-QAM 3.36 Mbps
10 codes 16-QAM 6.72 Mbps
15 codes 16-QAM 9.6 Mbps
15 codes 16-QAM 13.3 Mbps
1.8 Mbps
Max L1 data rate
3.6 Mbps
7.2 Mbps
10.1 Mbps
14.0 Mbps
Phase 1
Phase 2
Phase 3
Phase 4
15 codes, MIMO 16-QAM 26.6 Mbps 28.0 Mbps 3GPP R7
15 codes, MIMO? 64-QAM 3GPP R7
HSDPA TX-power
Common channels
DCH RT
DCH NRT
HSDPA NRT
PtxTarget
Max power
Power control head-room
Non-controllable power
Controllable power
Total transmittedcarrier power
NEW non-HSDPApower measurements
Power measurementsfrom the Node-B to
the RNC
In addition to power also code resource shared!
Agenda
Introduction
-> General Principal
• HSDPA Key Characteristics, New Features
Architectural Changes, Impact on RAN
Link Adaptation
HSDPA Channel Structure
HARQ Principle
HSDPA – Operating Principle
Packet Scheduling
HSDPA Mobility
HSDPA key characteristics (1)
Basic WCDMA Technology
Enhanced in HSDPAIncluded in HSDPA
Excluded from HSDPA
AMC
H-ARQ
TTI = 2 ms
Advanced PS
SHO
PC
Variable SF
Multi-code operation
HSDPA key characteristics (2)
The physical layer retransmission (ARQ function)
• R’99: RNC-based ARQ
• HSDPA: Node-B based fast H-ARQ
Packet scheduling
• R’99: RNC-based
• HSDPA: NodeB-based
Power control
• R’99: Fast PC
• HSDPA: Link adaptation function and AMC (adaptive modulation and coding)
Good spectral efficiency
• HSDPA: up to 15 multi-codes in parallel.
SF = 128
SF = 256
SF = 64
SF = 32
SF = 8
SF = 16
SF = 4
SF = 2
SF = 1
Codes for the cell common channels
Code for oneHS-SCCH
Codes for 5HS-PDSCH's
Downlink Code Allocation
•166 codes @ SF=256 available for the associated DCHs and non-HSDPA uses
•HSDPA with 5 codes allocated at cell MAC-hs start-up when HSDPA is enabled
•Code allocation is dynamic in future releases when more than 5 codes are allocated
New features (1/2)
Shared channel transmission
• HS-DSCH (high speed downlink shared channel)
• Supports up to 15 codes parallel
• Fixed spreading factor (16)
• Works in parallel to DCH
Higher-order modulation
• QPSK
• 16-QAM
Short transmission time interval (TTI)
• Dynamic channel code allocation interval of 2 ms
New features (2/2)
Fast link adaptation• Adjusts transmission parameters – not TX
power!• Users near Node B: QPSK 16-QAM (for
example)
Fast scheduling• Allocates the use of shared channel to UEs
with best radio conditions at certain time moment (Multi User Diversity)
• Scheduling is done at Node-B instead of RNC
Fast hybrid automatic-repeat-request (H-ARQ)• Request and retransmit missing data (UE
Node-B)• Combine information from original
transmission (Soft Combining)• Signalling with ACKs and NACKs
HSDPA Operating Prinicple
HSDPA - General Principle
Channel quality(CQI, Ack/Nack, TPC)
Data
BTS Tx pwr
Tx power for HSDPA
is constant
Tx power for HSDPA
is constant
Throughput
Throughput varies according
to channel quality
HSDPAR99-DCH
BTS Tx pwr
Tx power varies according to
channel quality (BLER)
Throughput
Throughput is “maintained”
Throughput is “maintained”
#channelisationCodes per UE
Only 1 variable SF code used per user
Only 1 variable SF code used per user
1
#channelisationCodes per UE
2
4
6
8
0-15 codes of SF16 used based on channel quality and UE/network capability
0-15 codes of SF16 used based on channel quality and UE/network capability
Agenda
Introduction
General Principal
• HSDPA Key Characteristics, New Features
-> Architectural Changes, Impact on RAN
Link Adaptation
HSDPA Channel Structure
HARQ Principle
HSDPA – Operating Principle
Packet Scheduling
HSDPA Mobility
Key Architectural ChangeThe PDCP, RLC and MAC-d layers are unchanged from the Release '99 and Release 4 architectureThe new functionalities of hybrid ARQ and scheduling/priority handling are included in the MAC layer• In the UTRAN side, these functions are included in a new entity called MAC-hs, which is located in the BTS• A new type of transport channel, the HS-DSCH, is introduced for HSDPA– It is controlled by the MAC-hs.
Iub
Affected by HSDPA
RNC
RRMAC
PS
HCLC
RM
PDCP
RLC
MAC
FP
Transport
Node B
FP
Transport
MAC-hs
WCDMAL1
O&M
Not affected by HSDPA
New entity for HSDPA
HSDPA Protocol Architecture
New MAC entity, MAC-hs added to the Node B
RNC still retains the RLC functionalities
WCDMA L1
UE
Iub/Iur
SRNCNode B
Uu
MAC-hs
RLC
NAS
HSDPA user plane
WCDMA L1
MAC-hs
TRANSPORT
FRAMEPROTOCOL
TRANSPORT
FRAMEPROTOCOL
MAC-dRLC
IuMAC-d
PHY
ATM
AAL2
HS - DSCH FP
MAC - d
RLC
PDCP
SRNC
PHY
ATM
AAL5
IP
UDP
GTP - U
PHY
ATM
AAL5
IP
UDP
GTP - U
User IP data
CN UE
PHY
WCDMA L1
WCDMA L1 ATM
AAL2
HS - DSCH FP MAC - hs MAC - hs
Node B MAC - d
RLC
PDCP
User IP data
PHY
ATM
AAL2
HS - DSCH FP
MAC - d
RLC
PDCP
SRNC
PHY
ATM
AAL5
IP
UDP
GTP - U
PHY
ATM
AAL5
IP
UDP
GTP - U
User IP data
CN UE
PHY
WCDMA L1
WCDMA L1 ATM
AAL2
HS - DSCH FP MAC - hs MAC - hs
Node B MAC - d
RLC
PDCP
User IP data
Uu Iub Iu - PS
HSDPA Protocol Stack incl. PS Core NW
HSDPA impact on RAN
Additional intelligence (HSDPA MAC – MAC hs) is installed at the NodeB.
Retransmission controlled by the NodeB leads to faster execution and shorter delay in case of retransmissions.
The Iub interface (NodeB-RNC) requires a flow control mechanism to ensure that NodeB buffers are used properly and there is no buffer overflow.
Pac
ket
Pac
ket
RLC ACK/NACK
L1 ACK/NACK
R’99 DCH / DSCH R’5 HS-DSCH
New Node B functionality for HSDPA
TerminalsNode BRNC
PacketsScheduler
& Buffer
ARQ &
Coding
ACK/NACK & Feedback Decoding
Flow Control
New Node B functions:Scheduler: Terminal scheduling, Coding & Modulation selection (16QAM as
new modulation)
ARQ Retransmissions Handling
Uplink Feedback Decoding
Flow Control towards SRNC
New terminal functionality for HSDPA
TerminalNode BRNC
PacketsARQ
Decoding
Soft Buffer
& Combining
ACK/NACK & Feedback
Generation
Flow Control
New terminal functions:
16 QAM demodulation
ARQ Retransmissions Handling
Soft buffer & combining
Fast Uplink Feedback Generation & encoding
Initial HSDPA terminals are data cards without voice capability
Sub frame Structure
WCDMA : 10ms frame (15 slots)
HSDPA: 2ms (3slots) -> Subframe
slot#0 slot#1 slot#2
HSDPA subframe (2 ms)
Quick Snapshot: Changes Introduced by HSDPA
Shorter radio frame ( 2ms TTI)
Use of 16QAM modulation in addition to QPSK modulation
Code multiplexing combined with time multiplexing
New Channels in DL and UL
Use of hybrid automatic-repeat-request (HARQ)
MAC-hs functionality in Node-B
Agenda
Introduction
General Principal
• HSDPA Key Characteristics, New Features
Architectural Changes, Impact on RAN
-> Link Adaptation
HSDPA Channel Structure
HARQ Principle
Cell Change order
Link adaptation: Modulation
QPSK
2 bits / symbol =480 kbit/s/HS-PDSCH =
max. 7.2 Mbit/s
16QAM
4 bits / symbol =960 kbps/HS-PDSCH =
max. 14.4 Mbit/s
1011 1001
10001010
0001 0011
00100000
0100 0110
01110101
1110 1100
11011111
Q
I
10 00
0111
Q
I
Fast Link Adaptation in HSDPA
0 2 0 4 0 6 0 8 0 1 00 1 20 1 40 1 60- 202468
10121416
Time [number of TTIs]
QPSK1/4
QPSK2/4
QPSK3/4
16QAM 2/4
16QAM 3/4
Inst
anta
neou
s Es
No
[dB]
C/I received by UE
Link adaptation
mode
C/I varies with fading
BTS adjusts link adaptation mode with a few ms delay based on channel quality
reports from the UE
Agenda
Introduction
General Principal
• HSDPA Key Characteristics, New Features
Architectural Changes, Impact on RAN
Link Adaptation
-> HSDPA Channel Structure
HARQ Principle
HSDPA – Operating Principle
Packet Scheduling
HSDPA Mobility
HS-SCCH
HS-PDSCH
HS-DPCCH
Associated DPCH DL: 1 DPDCH & 1 DPCCH
HS-SCCH: High speed shared control channel. It indicates the recipient UE Id, modulation, number of codes, relevant HARQ info. 1 HS-SCCH per cell in case of no code multiplexing.
HS-PDSCH: High speed physical downlink shared channel. Carries a variable amount of user data, for a single user in case of no code multiplexing.
HS-DPCCH: High speed dedicated physical control channel. Used by the UE to send ACK / NACK and CQI (Channel Quality Indicator)
Associated DPCH UL: DCH channel used to send UL user data, e.g. RLC and TCP ACKs, HTTP requests etc.
Associated DPCH DL: DCH channel used to transmit power control information for the UL associated DCH and other potentially needed signalling (e.g. bearer reconfgurations etc.)
Node-BUE
1
5
3
2
1
5
3
2
per cell
per user 4
4
Associated DPCH UL: 1 DPDCH & 1 DPCCH
New Channels on Air-Interface introduced for HSDPA
HSDPA Channels – Transport Channel
HS-DSCH
WCDMA System normally operates on DCH which brings maximum system
performance with continuous data.
HSDPA introduces new transport channel, HS-DSCH, which makes efficient use of radio resources and takes into account bursty packet data
HS-DSCH shares multiple codes among several users
Time Multiplexing in HSDPA
HSDPA Physical Channels (1/4)
HSDPA channels – Physical Channel (2/4)
HS-PDSCH (High Speed DL Shared Channel)
• Carries the user data in the DL.
• Higher modulation scheme (16QAM), lower encoding redundancy leading to high peak data rates.
• TTI (Transmission Time Interval), interleaving period = 2 ms (In R’99, TTI = 10/20/40/80 ms).
• Fixed SF (16), support multi-code transmission, as well as multiplexing of different users (15 – maximum capability, depends on the UE category: 5/10/15).
• Users check the information on the HS-SCCH to determine which HS-DSCH codes to despread.
• HS-PDSCH has always DL DPCH associated (signal radio bearer for layer 3 signaling, power control command for UL HS-DPCCH, etc.)
HSDPA Channels- physical channels (3/4)
HS-SCCH (High Speed Shared Control Channel)
• Carries the information needed for HS-DSCH demodulation
• If there is no data on HS-DSCH, HS-SCCH is not assigned.
• The HS-SCCH uses SF 128, accomodating 40 bits per slot.
• Each HS-SCCH block has a three–slot duration divided into 2 functional parts:
– First part (first slot) carries the time-crucial information needed to start the demudaltion process in due time: HS-DSCH codes, indication if QPSK or 16QAM modulation is used on HS-DSCH.
– Second part (next two slots) contains CRC (cyclic redundancy check) for checking HS-SCCH, ARQ process number, redundancy version.
HSDPA Channels - physical channels (4/4)
HS-DPCCH (UL High Speed Dedicated Physical Control Channel)
• Carries ACK/NACK information for the L1 retransmissions.
• Carries CQI (DL Channel Quality Indicator) to be used by NodeB scheduler to determine to which terminal to transmit and at which rate.
• Intensively discussed in the 3GPP forum, feedback method is not easy to be standardized due to differences in the terminals.
CQI Reporting from UECQI TBS codes M (dB)1 137 1 QPSK 02 173 1 QPSK 03 233 1 QPSK 04 317 1 QPSK 05 377 1 QPSK 06 461 1 QPSK 07 650 2 QPSK 08 792 2 QPSK 09 931 2 QPSK 010 1262 3 QPSK 011 1483 3 QPSK 012 1742 3 QPSK 013 2279 4 QPSK 014 2583 4 QPSK 015 3319 5 QPSK 016 3565 5 16QAM 017 4189 5 16QAM 018 4664 5 16QAM 019 5287 5 16QAM 020 5887 5 16QAM 021 6554 5 16QAM 022 7168 5 16QAM 023 7168 5 16QAM -124 7168 5 16QAM -225 7168 5 16QAM -326 7168 5 16QAM -427 7168 5 16QAM -528 7168 5 16QAM -629 7168 5 16QAM -730 7168 5 16QAM -8
UE should report the CQI for which the BLER probability would not exceed 10% on HS-DSCH in measured condition (PCPICH +
Algorithm to calculate CQI value is not specified by 3GPP.
CQI reporting can have UE specific differences.
TS25.214 says :
“Based on an unrestricted observation interval, the UE shall report the highest tabulated CQI value for which a single HS-DSCH sub-frame formatted with the transport block size, number of HS-PDSCH codes and modulation corresponding to the reported or lower CQI value could be received in a 3-slot reference period ending 1 slot before the start of the first slot in which the reported CQI value is transmitted and for which the transport block error probability would not exceed 0.1. “
Agenda
Introduction
General Principal
• HSDPA Key Characteristics, New Features
Architectural Changes, Impact on RAN
Link Adaptation
HSDPA Channel Structure
-> HARQ Principle
HSDPA – Operating Principle
Packet Scheduling
HSDPA Mobility
Stop and Wait Protocol (SAW)
Transmission of new blocks is stopped until and ACK/NACK is received
• Minimal protocol overhead (no sequence numbers needed)
• Reduced storage requirements at UE
• Problem: Channel is unused until ACK/NACK is received
N Channel Hybrid ARQ (HARQ)
H-ARQ principles (1)Fast H-ARQ algorithm rapidly requests the retransmission of missing data entities.
Retransmitted data entities are soft combined with the original transmission before message decoding.
Since, the H-ARQ mechanism resides in the NodeB (MAC-hs), requests can be done immediatly.
This way, probability of successful combining is increased.
If all data is correctly decoded, the ACK message is sent on the associated UL channel (HS-DPCCH).
H-ARQ requires some memory in the UE to buffer the soft information.
Two strategies of H-ARQ:• IR (incremental redundancy)
• CC (chase combining)
H-ARQ principles (2)
The idea of the CC is to transmit the same packet again
• Receiver combines these two copies prior to decding
The idea of the IR is to transmit additional redundant information that is incrementally transmitted if the decoding fails on the first attempt.
• Causes increase of the effective coding gain with the number of retransmissions.
• Full IR (inlcudes parity bits in every coded word) requires significant UE memory capabilities.
H-ARQ
HARQ is one of the most important features in HSDPA concept to enhance the packet data transmission capability of WCDMA system
It controls the packet retransmission on layer 1 level to reduce the retransmission delay
There is one HARQ entity per UE in UTRAN side
• Each HARQ entity consists of several HARQ processes (i.e. the so called SAW channels)
HS-DSCH Physical Layer Category
Number of HARQProcesses
NIR(in bits)
Category 1 2 9600
Category 2 2 14400
Category 3 3 9600
Category 4 3 12800
Category 5 6 9600
Category 6 6 11200
Category7 6 19200
Category8 6 22400
Category9 6 28800
Category10 6 28800
Category 11 3 4800
Category 12 6 4800
• A number of parallel HARQ processes are established at the same time to support the HARQ protocol
• The number of HARQ processes is determined by MAC-hs as shown in table on the right
• MAC-hs gets the HS-DSCH Physical Layer Category information in the NBAP: RADIO LINK SETUP REQUEST message or the NBAP: RADIO LINK RECONFIGURATION PREPARE message
Agenda
Introduction
General Principal
• HSDPA Key Characteristics, New Features
Architectural Changes, Impact on RAN
Link Adaptation
HSDPA Channel Structure
HARQ Principle
-> HSDPA – Operating Principle
Packet Scheduling
HSDPA Mobility
HSDPA Operating Prinicple
HSDPA Peak Bit Rates
Coding rateCoding rate
QPSKQPSK
Coding rateCoding rate
1/41/4
2/42/4
3/43/4
5 codes5 codes 10 codes10 codes 15 codes15 codes
600 kbps600 kbps 1.2 Mbps1.2 Mbps 1.8 Mbps1.8 Mbps
1.2 Mbps1.2 Mbps 2.4 Mbps2.4 Mbps 3.6 Mbps3.6 Mbps
1.8 Mbps1.8 Mbps 3.6 Mbps3.6 Mbps 5.4 Mbps5.4 Mbps
16QAM16QAM
2/42/4
3/43/4
4/44/4
2.4 Mbps2.4 Mbps 4.8 Mbps4.8 Mbps 7.2 Mbps7.2 Mbps
3.6 Mbps3.6 Mbps 7.2 Mbps7.2 Mbps 10.7 Mbps10.7 Mbps
4.8 Mbps4.8 Mbps 9.6 Mbps9.6 Mbps 14.4 Mbps14.4 Mbps
RAN05
RAN05.1
UE categories
12 different UE categories
Possible receiver types Rake, Equalizer, 2-Equalizer
Theoretical peak bit rate up to 14 Mbps
1.8 Mbps and 3.6 Mbps capability expected initially
10
9
7/8
5/6
3/4
1/2
12
11
UE Category
-
-
-
3.6 Mbps
1.8 Mbps
1.2 Mbps
1.8 Mbps
0.9 Mbps
5 Codes
--36302QPSK only
--36301QPSK only
QPSK/16QAM
QPSK/16QAM
QPSK/16QAM
QPSK/16QAM
QPSK/16QAM
QPSK/16QAM
Modulation
14.0 Mbps
10.1 Mbps
-
-
-
-
15 Codes
-279521
-202511
7.2 Mbps144111
-72981
-72982
-72983
10 CodesTransportBlock sizeInter-TTI
(First one has smaller HARQ memory.)
Inter-TTI interval
Inter-TTI interval: Number of sub frames between transmissions to a UE
DTXData DTX DTXData
Inter-TTI = 3
DTXData Data DataDTX
Inter-TTI = 2
HSDPA Cell throughput
780 kbps
DCH: 410 kbps
1090 kbps
HSDPA: 670 kbps
DCH: 410 kbps
1320 kbps
HSDPA: 910 kbps
DCH: 780 kbps
HSDPA: N.A.
HSDPA 16QAMRR scheduling
HSDPA 16QAMPF scheduling
No HSDPA
43% Gain
21% Gain
Simulated cell throughput with mixed HSDPA and Rel.99 traffic.
5 codes assumed.
Pedestrian propagation channel.
Packet Scheduling in HSDPA
Reasons why UE sometimes cannot be scheduled:
• Some UEs do not support reception in consecutive TTIs.
• BTS cannot receive Ack/Nack because of poor uplink quality.
• All HARQ processes of UE are full and next transmission would be a new one.
1st TTI
2nd TTI
3rd TTI
Some Scheduler TypesProportional Fair Resource (P-FR)
• UE with best radio condition is chosen
• On short time-scale, different UEs get different resources.
• On medium time-scale, similar fairness to Round-Robin.
• Implemented in RAN05.1
Maximum Throughput (M-TP)
• The UE with the highest instant-aneous throughput is chosen.
• Average throughput and cell capacity maximised.
• Lots of UEs get zero throughput.
• Not “fair” among queues on short or even medium time-scale.
Round-Robin (RR) = Fair Resource (FR)
• UE in front of queue is scheduled, then moved to back of queue.
• Each UE gets same amount of resources. The throughput depends on its link conditions.
• Simple.
• Used in RAS05
Fair Throughput (FT)
• Each UE gets same throughput.
• UE in bad conditions has to be given more resources.
• Cell capacity is bad.
UE2
Channel quality(CQI, Ack/Nack, TPC)
Channel quality(CQI, Ack/Nack, TPC)
Data
Data
UE1
WBTS scheduling operates at 2ms rate and can utilize information on the instantanous channel conditions for each user
WBTS scheduling operates at 2ms rate and can utilize information on the instantanous channel conditions for each user
Multi-user selection diversity(give shared channel to “best” user)
TTI 1 TTI 2 TTI 3 TTI 4
USER 1 Es/N 0USER 2 Es/N 0
Scheduled user
Proportional Fair Idea (RAS05.1)
Agenda
Introduction
General Principal
• HSDPA Key Characteristics, New Features
Architectural Changes, Impact on RAN
Link Adaptation
HSDPA Channel Structure
HARQ Principle
HSDPA – Operating Principle
Packet Scheduling
-> HSDPA Mobility
HSDPA mobility in RAS05
• Serving Cell Change switches the user from HS-DSCH to Cell_FACH then back to HS-DSCH
HS-DSCH coverage HS-DSCH coverage
Service in
HSDPA
Switching to Cell_FACH within the SHO area
UE on HS-DSCH
Cell A Cell B
HSDPA
DCH
0
Throughput
64kbps
128kbps or 384kbps according to parameter settings
Details on Cell Change via cell-FACH
•HSDPA Serving Cell Change via Cell-FACH feature is used only in intra frequency handover cases, in case of IFHO or ISHO the original DCH switching procedures are used
•If the user was moved to Cell-FACH because of intra frequency handover no HSDPA user penalty timers are used on Cell-FACH, the user will be immediately switched to a new HSDPA connection when there is a data volume request either from the UE or RNC
•If the user was moved to Cell-FACH because of low throughput then the HSDPA user penalty timers are used on Cell-FACH
•If the HSDPA user moves to non-HSDPA cell, the user in HO area will be moved to Cell-FACH. The user will be immediately switched to the DCH of the requested bit rate when there is a data volume request either from the UE or RNC (no need for first DCH0/0 DCH Initial bit rate DCH Final bit rate)
In RAS05, UE goes to cell_FACH in the current serving cell. Possible cell reselection to best server happens in cell_FACH.
Improved HS-DSCH to cell_FACH switching
Target cell (cell with best CPICH Ec/No in the measurement set) informed in the RB reconfiguration message, when UE is commanded to cell_FACH
There is no need for cell reselection in cell_FACH, as the UE goes directly to strongest cell in cell_FACH.
Scrambling code of the strongest cell in the measured set informed
to UE.
Establishment of HSDPA Call
AAL2SIG:ECF
AAL2SIG:ERQ
Radio Link Reconfigure Ready
UE RNC SGSNNode B
NBAP: Radio Link Reconfigure Prepare
PDP Established
Measurement Report: e4a
FP: Downlink Sync
FP: Uplink Sync
Radio Link Reconfiguration Commit
RRC: Radio Bearer Reconfiguration (DCH)
RRC: Radio Bearer Reconfiguration Complete (DCH)
Measurement Control
AAL2SIG:ECF
AAL2SIG:ERQ
FP: Downlink Sync
FP: Uplink Sync
HSDPA Traffic
HS-DSCH: Capacity Request
HS-DSCH: Capacity Allocation
1. Intra Node-B serving HS-DSCH cell change
2. Inter Node-B serving HS-DSCH cell change
3. HS-DSCH to DCH switch (needed if the UE is moving to a cell without HSDPA support)
RAS05.1 provides full intra-frequency mobility for HSDPA users and enables HSDPA also in SHO
region
HSDPA capable cellHSDPA not supported
12
3
HSDPA Handover UL/DL DCH = soft/softer HO ; DL HS-DSCH = serving cell change
Mobility in RAS05.1
Agenda
Introduction
General Principal
• HSDPA Key Characteristics, New Features
Architectural Changes, Impact on RAN
Link Adaptation
HSDPA Channel Structure
HARQ Principle
HSDPA – Operating Principle
Packet Scheduling
HSDPA Mobility
-> Measurement Results
32-B Ping Measurements Average Round Trip Time 78 ms
Reply from 10.20.143.10: bytes=32 time=83ms TTL=126
Reply from 10.20.143.10: bytes=32 time=73ms TTL=126
Reply from 10.20.143.10: bytes=32 time=83ms TTL=126
Reply from 10.20.143.10: bytes=32 time=83ms TTL=126
Reply from 10.20.143.10: bytes=32 time=84ms TTL=126
Reply from 10.20.143.10: bytes=32 time=83ms TTL=126
Reply from 10.20.143.10: bytes=32 time=73ms TTL=126
Reply from 10.20.143.10: bytes=32 time=83ms TTL=126
Reply from 10.20.143.10: bytes=32 time=73ms TTL=126
Reply from 10.20.143.10: bytes=32 time=83ms TTL=126
Reply from 10.20.143.10: bytes=32 time=74ms TTL=126
Reply from 10.20.143.10: bytes=32 time=83ms TTL=126
…
Reply from 10.20.143.10: bytes=32 time=71ms TTL=126
Reply from 10.20.143.10: bytes=32 time=82ms TTL=126
Reply from 10.20.143.10: bytes=32 time=72ms TTL=126
Reply from 10.20.143.10: bytes=32 time=82ms TTL=126
Reply from 10.20.143.10: bytes=32 time=71ms TTL=126
Reply from 10.20.143.10: bytes=32 time=81ms TTL=126
Reply from 10.20.143.10: bytes=32 time=81ms TTL=126
Reply from 10.20.143.10: bytes=32 time=73ms TTL=126
Reply from 10.20.143.10: bytes=32 time=82ms TTL=126
Reply from 10.20.143.10: bytes=32 time=72ms TTL=126
Reply from 10.20.143.10: bytes=32 time=82ms TTL=126
Reply from 10.20.143.10: bytes=32 time=71ms TTL=126
Reply from 10.20.143.10: bytes=32 time=81ms TTL=126
Reply from 10.20.143.10: bytes=32 time=71ms TTL=126
Round trip time
0
10
20
30
40
50
60
70
80
90
100
1
Samples
[ms]
Round trip time 71-84
ms
Multiuser Capacity Sharing Works
0
200
400
600
800
1000
1200
1400
1600
1800
1 2 3 4 16
Number of users
kb
ps
Total cell throughputUser throughput
Throughput per user decreases when more
users download data (as expected)
Total cell throughput remains constant
regardless of the number of simultaneous users
0
200
400
600
800
1000
1200
1400
1600
1800
-110-108-106-104-102-100-98-96-94
RSCP [dBm]
kbp
s
Simulated flat fading UE noise -101 dBmMeasured OptionSimulated flat fading UE noise -99 dBmMeasured Novatel
Throughput in Low Signal Power in the Field
700-900 kbps at RSCP = –108 dBm
level
6 W HSDPA power assumed