Enhanced High-Speed Packet Access HSPA+_ws12.pdf · UMTS Networks Andreas Mitschele-Thiel, Jens...

Enhanced High-Speed Packet AccessHSPA+

u Background: HSPA Evolutionu Higher data ratesu Signaling Improvementsu Architecture Evolution/ Home NodeB

UMTS Networks 2Andreas Mitschele-Thiel, Jens Mückenheim Nov. 2012

HSPA+ (HSPA Evolution) Background

u For operators deploying High Speed Packet Access (HSPA*) now, there is theneed to continue enhancing the HSPA technologyu 3GPP Long Term Evolution (LTE) being standardized now, but not

backwards compatible with HSPAu 477 HSDPA networks in service in 177 countries (Oct. 12)**u Investment protection needed for current HSPA deployments

u HSPA+ effort introduced in 3GPP in March 2006u Initiated by 3G Americas & the GSMAu HSPA+ defines a broad framework and set of requirements for the

evolution of HSPAu Rel.-7: improvements mainly in downlinku Rel.-8: mainly uplink enhancementsu Rel.-9/10: further improvements

*HSPA is the combination of HSDPA and HSUPA**http://www.4gamericas.org -> Statistics


HSPA+ Goals

Based on the importance of the HSPA-based radio network, 3GPPagreed that HSPA+ should:

u Provide spectrum efficiency, peak data rates & latency comparable toLTE in 5 MHz

u Exploit full potential of the CDMA air interface before moving to OFDM

u Allow operation in an optimized packet-only mode for voice and datau Utilization of shared channels only

u Be backward compatible with Release 99 through Release 6u Offer a smooth migration path to LTE/SAE through commonality, and

facilitate joint technology operationu Ideally, only need a simple infrastructure upgrade from HSPA to HSPA+u HSPA evolution is two-fold

u Improvement of the radiou Architecture evolution


Higher Order Modulations (HOMs)

BPSK2 bits/symbol

16QAM4 bits/symbol

64QAM6 bits/symbol

Uplink Downlink

u Increases the peak data rate in a high SNR environmentuVery effective for micro cell and indoor deployments


Peak Rate Performance Benefits of HSPA+

0

5

10

15

20

25

30

35

40

45

50

Peak

Thro

ughp

utin

Mbp

s

14

21

28

42

5.7

11.5

HSDPA

HSPA+64QAM

HSPA+16QAM

2x2 MIMO

HSPA+64QAM*

2x2 MIMO

HSUPA

HSPA+16QAM

Downlink

Uplink

*Release 8

Uplink and Downlink peakrates similar to LTE peakrates in 5 MHz

uMajor increase HSPA peakrates by Higher OrderModulations

uData rate benefits for usersin ideal channel conditions(e.g. static users, fixedusers close to the cellcenter, lightly loadedconditions)


HSDPA Performance with 64QAM

Without 64-QAM With 64-QAM Gain

Cell Throughput 6.9 Mbit/s 7.65 Mbit/s 10.7%

95%-tile User Throughput 7.1 Mbit/s 8.7 Mbit/s 22.5%

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

Cat 10/ 15 users Cat 14/ 15 users

thro

ughp

ut/k

bps

average user throughput 95% user throughput ave. cell throughput

Single micro-cell scenario, advanced receivers required


16-QAM for E-DCH

u 16-QAM being considered in the uplink for HSPA Evolution, for use with the2ms TTI and with 4 multicodes (2xSF2 + 2xSF4)u Increases peak rate from 5.76 Mbps to 11.52 Mbps

u Simulation results showed:u 16 QAM requires very high SNR at the receiveru 16 QAM can be used only in case of one single HSUPA active user per cell

BPSK

BPSK

BPSK

BPSK

SF2

SF2

SF4

SF4

I

Q

I

Q

SF2

SF4

16 QAM

I

Q

16 QAM

I

Q


Coding/Modulation/Weighting/Mapping

Basic MIMO Channel

§ The HSDPA MIMO channel consists of 2 Tx and 2 Rx antennas§ Each Tx antenna transmits a different signal§ The signal from Tx antenna j is received at all Rx antennas i§ Channel capacity can be increased by up to a factor of two

Weighting/DemappingDemodulation/Decoding

Tx Rx

H

HVUH L=


MIMO in HSPA+

Release 7 MIMO for HSDPA (D-TxAA)u 2 x 2 MIMO schemeu 4 rank-1 precoding vectors and 4 rank-2 precoding matrices are defined

u The rank-2 matrices are unitary (the columns are orthogonal)u The mobile reports the rank of the channel and the preferred precoding

weights periodicallyu Dynamic switching between single stream and dual stream transmission is

supported by the NodeB scheduler

Weight Generation

w1 w4

Determine weight infomessage from the uplink

w2 w3

TrCHprocessing

HS-DSCH TrCHprocessing

HS-DSCH

Spread/scramble

Primarytransport block

Primary: Always present for scheduled UE

Secondary: Optionally present for scheduled UE

Secondarytransport block

å

Ant1

Ant2

å

CPICH1

CPICH2

w1

w2

w3

w4

å

å


MIMO Performance Benefits

u 2x2 D-TxAA MIMO scheme doubles peak rate from 14.4 Mbps to 28.8 Mbpsu 2x2 D-TxAA MIMO provides significant experienced peak, mean & cell edge

user data rate benefits for isolated cells or noise/coverage limited cellsu 2x2 D-TxAA MIMO provides 20%-60% larger spectral efficiency than 1x2

00.250.5

0.751

1.251.5

1.752

Near Cell Center Average CellLocation

Cell Edge

Data

Rat

eG

ain

ofM

IMO

vs.

SIS

Ofo

ran

Isol

ated

Cell SISO (1x1)

MIMO (2x2)Note: All gainsnormalized toNear Cell CenterSISO Data Rate

0

20

40

60

80

100

Interference LimtedSystem

Isolated Cell

Spec

tralE

ffici

ency

Gai

n(%

)of2

x2M

IMO

over

1x2

LMM

SE


Overview of Dual Cell Operation

3GPP Rel-8 scope:u The dual cell operation only applies to downlink HS-DSCH

u Uplink traffic is carried in one frequencyu The two cells belong to the same Node-B and are on adjacent carriersu The two cells operate with a single TX antenna

u Max two streams per user

Improvements in Rel.-9u Dual-Band HSDPAu MIMO in dual cell operationu Dual Cell uplink

Multi-carrier HSDPA

Node-B

F1UEF2

DLDL

5 MHz 5 MHz

UL5 MHz

2.1GHzUL

UTRAN configures one of the cell as theserving cell for the uplink


Dual Cell HSDPA Operation for Load Balancing

Dual Cell HSDPA can optimally balance the load on two HSDPA carriers by schedulingactive users simultaneously or on least loaded carrier at given TTI

Simple traffic and capacitymodel

Avg Transfer size : 1000 kbytes

Avg Time between transfers :60 sec

No gain at very high load

Dual Cell HSDPA operation versus Two legacy HSDPA carriers

0

1000

2000

3000

4000

5000

6000

7000

8000

0 10 20 30 40 50 60

Nb of users in sector footprint

Thro

ughp

utin

kbps

Avg user throughput (2 HSDPA carriers)Avg Sector throughput (2 HSDPA carriers)Avg user throughput (Dual Cell HSDPA operation)Avg Sector throughput (Dual Cell HSDPA operation)


Enhanced Layer-2 Support for High Data Rates

u Release 6 RLC layer cannot supportnew peak rates offered by HSPA+features such as MIMO & 64-QAMu RLC-AM peak rate limited to ~13

Mbps, even with aggressivesettings for the RLC PDU size andRLC-AM window size

u Release 7 introduces new Layer-2features to improve HSDPAu Flexible RLC PDU sizeu MAC-ehs layer segmentation/

reassembly (based on radioconditions)

u MAC-ehs layer flow multiplexingu Release 8 improves E-DCH

u MAC-i/ MAC-is

Rel’7

2

1500 byte IP packet

RLC-AM

MAC-ehs

RLC-AM PDU

1500

15001

MAC-ehs PDU

Traffic flow i for user k

2

1500 byte IP packet

RLC-AM

RLC-AM PDU

1500

1500

Traffic flow j for user k

22 bits

802 802

1500 byte IP packet

RLC-AM

802

MAC-hs

802 802802

RLC-AM PDU

MAC-hs PDU

x19

..

.. Rel’6

Traffic flow i for user k


MAC-ehs in NodeB

MAC-ehs Functions (TS 25.321)u Flow Controlu Scheduling/ Priority handlingu HARQ handlingu TFRC Selectionu Priority Queue Muxu Segmentation

MAC-ehs

MAC – Control

HS-DSCH

TFRC selection

Priority Queuedistribution

Associated DownlinkSignalling

Associated UplinkSignalling

MAC-d flows

PriorityQueue

Scheduling/Priority handling

PriorityQueue

PriorityQueue

Segmentation

Segmentation

Segmentation

Priority Queue MUX

HARQ entity


HSDPA – UE Physical Layer Capabilities

HS-DSCHCategory

Maximumnumber ofHS-DSCH

multi-codes

Supported ModulationFormats

Minimuminter-TTIinterval

MaximumMAC-hsTB size

Total numberof soft channel

bits

Theoreticalmaximumdata rate(Mbit/s)

Category 6 5 QPSK, 16QAM 1 7298 67200 3.6Category 8 10 QPSK, 16QAM 1 14411 134400 7.2Category 9 15 QPSK, 16QAM 1 20251 172800 10.1Category 10 15 QPSK, 16QAM 1 27952 172800 14.0Category 13 15 QPSK, 16QAM, 64QAM 1 35280 259200 17.6Category 14 15 QPSK, 16QAM, 64QAM 1 42192 259200 21.1Category 15 15 QPSK, 16QAM 1 23370 345600 23.3Category 16 15 QPSK, 16QAM 1 27952 345600 28.0Category 17 15 QPSK, 16QAM, 64QAM/

MIMO: QPSK, 16QAM1 35280/

23370

259200/

345600

17.6/

23.3Category 18 15 QPSK, 16QAM, 64QAM/

MIMO: QPSK, 16QAM1 42192/

27952

259200/

345600

21.1/

28.0Category 19 15 QPSK, 16QAM, 64QAM 1 35280 518400 35.2Category 20 15 QPSK, 16QAM, 64QAM 1 42192 518400 42.2

Note: UEs of Categories 15 – 20 support MIMO cf. TS 25.306


E-DCH – UE Physical Layer Capabilities

E-DCHCategory

Max. num.Codes

Min SF EDCH TTI Maximum MAC-eTB size

Theoretical maximum PHYdata rate (Mbit/s)

Category 1 1 SF4 10 msec 7110 0.71

Category 2 2 SF4 10 msec/2 msec

14484/2798

1.45/1.4



20000/5772

2.0/2.89



20000/11484

2.0/5.74

Category 7(Rel.7)

4 SF2 10 msec/2 msec

20000/22996

2.0/11.5

NOTE 1: When 4 codes are transmitted in parallel, two codes shall betransmitted with SF2 and two codes with SF4NOTE 2: UE Category 7 supports 16QAM

cf. 25.306


Continuous Packet Connectivity (CPC)

u Uplink DPCCH gating duringinactivity à significant reductionin UL interference

u F-DPCH gating during inactivity

u New uplink DPCCH slot formatoptimized for transmissionDPCCH only

DataPilot

u HS-SCCH-less transmission introduced to reduce signaling bottleneck for real-time-services on HSDPA

Prior to Rel-7

Rel-7 using CPC

DataPilot


CPC Performance Benefits

u CPC provides up to a factor of two VoIP on HSPA capacity benefit comparedto Rel-99 AMR12.2 circuit voice and 35-40% benefit compared to Rel-6 VoIPon HSPA

0

0.5

1

1.5

2

2.5

3

AMR12.2 AMR7.95 AMR5.9VoIP

Cap

acity

Gai

nof

CPC R'99 Circuit Voice

VoIP on HSPA (Rel'6)*VoIP on HSPA (CPC)*

Note: Allcapacity gainsnormalized toAMR12.2Circuit VoiceCapacity

* All VoIP on HSPA capacities assume two receive antennas in the terminal


“Always On” Enhancement of CPC

u CPC allows UEs in CELL_DCH to “sleep” during periods of inactivityu Reduces signaling load and battery consumption (in combination with DRX)

u Allows users to be kept in CELL_DCH with HSPA bearers configuredu Need to page and re-establish bearers leads to call set up delay

Incomingcall Page UE

PagingResponse

Re-establishbearers

Send data

Without CPC, userstypically kept inURA_PCH or CELL_PCHstate to save radioresources and battery

UE inURA_PCH

CPC allows users tokept in CELL_DCH

Send data almostImmediately

(<50ms reactivation)

Incomingcall

UE inCELL_DCH

Avoids several hundredms of call setup delay

CELL_FACH

CELL_DCH


Enhanced CELL_FACH & Enhanced Paging Procedure

u UEs are not always kept in CELL_DCHstate, eventually fall back toCELL_PCH/URA_PCH

u HSPA+ introduces enhancements toreduce the delay in signaling thetransition to CELL_DCH à use ofHSDPA in CELL_FACH andURA/CELL_PCH states instead of S-CCPCHu Enhanced CELL_FACHu Enhanced Paging procedure

u In Rel.-8 improved RACH procedureu Direct use of HSUPA in CELL_FACH

Incomingcall Page UE

PagingResponse

Re-establishbearers

Send data

UE inURA_PCH

CELL_FACH

CELL_DCH

Use HSDPA forfaster

transmission ofsignalingmessages

à 2ms framelength with up to4 retransmissions


E-RACH – High level description

u RACH preamble ramping as in R’99 with AICH/E-AICH acknowledgementu Transition to E-DCH transmission in CELL_FACH

u Possibility to seamlessly transfer to Cell_DCHu NodeB can control common E-DCH resource in CELL_FACH

u Resource assignment indicated from NodeB to UE

10 ms

#0 #1 #2 #3 #14#13#12#11#10#9#8#7#6#5#4#0 #1 #2 #3 #14#13#12#11#10#9#8#7#6#5#4tp-

a

#0 #1 #2 #3 #14#13#12#11#10#9#8#7#6#5#4#0 #1 #2 #3 #14#13#12#11#10#9#8#7#6#5#4PRACHaccessslots

10 ms

Access slot set 1 Access slot set 2

#0 #1 #2 #3 #14#13#12#11#10#9#8#7#6#5#4#0 #1 #2 #3 #14#13#12#11#10#9#8#7#6#5#4

Transmission startswith power ramping

on preamblereserved for E-DCH

access

NodeB responds byallocating common E-DCH

resources

UE starts common E-DCHtransmission.

F-DPCH for power control, E-AGCHfor rate control, E-HICH for HARQ


HSPA+ Architecture Evolution

u Integration of some or all RNC functions into the NodeB provides benefits in terms of:u Network simplicity (fewer network elements)u Latency (fewer handshakes, particularly in combination with One-Tunnel)u Synergy with LTE (serving GW, MME, eNB)

u Backwards compatible with legacy terminalsu Central management of common resources

NodeB

RNC

SGSN

GGSN

Traditional HSPAArchitecture

User Plane

Control Plane

NodeB

RNC

SGSN

GGSN

HSPA with One-TunnelArchitecture

NodeB+

SGSN

GGSN

HSPA+ with One-TunnelArchitecture for PS services


Evolved HSPA Architecture – Full RNC/NodeB collapse

u 2 deployment scenarios: standalone UTRAN or carrier sharing with “legacy”UTRAN

EvolvedHSPANodeB

SGSN

GGSN

Userplane: Iu/Gn(”one tunnel”)Control

plane: Iu

Iur

EvolvedHSPANodeB

SGSN

GGSN


plane: Iu

Iur

RNC

NodeBNodeB

” Legacy”UTRAN

Iu

Evolved HSPA- stand-alone Evolved HSPA- with carrier sharing

EvolvedHSPANodeB

SGSN

GGSN


plane: Iu

Iur

EvolvedHSPANodeB

SGSN

GGSN


plane: Iu

RNC

NodeBNodeB

” Legacy”UTRAN

Iu

Evolved HSPA- stand-alone Evolved HSPA- with carrier sharing


Home NodeB – Background

u Home NodeB (aka Femtocell) located atthe customers premiseu Connected via customers fixed line

(e.g. DSL)u Small power (~100mW) to only

provide coverage inside/ close tothe building

u Advantagesu Improved coverage esp. indooru Single device for home/ on the

moveu Special billing plans (e.g. home

zone)

u Challengesu Interferenceu Securityu Costs

IP Network

UE

Gateway

OperatorCN


CN Interface

Iuh

Iu-CS/PS

Home NodeB architecture principles based on extending Iu interfacedown to HNB (new Iuh interface)

u Approach

u Leverage Standard CN Interfaces (Iu-CS/PS)

u Minimise functionality within Gateway

u Move RNC Radio Control Functions toHome NodeB and extend Iu NAS &RAN control layers over IP network

u Features

u Security architecture

u Plug-and-Play approach

u Femto local control protocol

u CS User Plane protocol

u PS User Plane protocol

u HMS interface

RNC HNB-GW

NodeB HNB

RAN Gateway Approach with new “Iuh” Interface

Mobile CS/PS Core


HSPA+ Status & Outlook

u The HSPA+ enhancements seem quite promising for network deploymentu Investment protection for the existing HSPA operatorsu Fill the gap before deployment of LTEu Provide alternatives to LTE in some selected areas

u Currently, 234 HSPA+ networks are in service in 113 countries(Oct 2012)**u Almost using 64QAM (often also with DC)u Only a few ones with MIMO

u 3GPP is working on further HSPA enhancementsu Release 10: 4-carrier HSDPAu Release 11: 8-carrier HSDPA, 4x4 HSDPA MIMO, HSDPA multipoint

transmission, UL MIMO + 64QAM


HSPA+ References

u Papers:u H. Holma et al: “HSPA Evolution,” Chapter 15 in Holma/ Toskala:

“WCDMA for UMTS,” Wiley 2010u R. Soni et al: “Intelligent Antenna Solutions for UMTS: Algorithms and

Simulation Results,” Communications Magazine, October 2004, pp. 28–39

u Standardsu TS 25.xxx series: RAN Aspectsu TR 25.308 “HSDPA: UTRAN Overall Description (Stage 2)”u TR 25.319 “Enhanced Uplink: Overall Description (Stage 2)”u TR 25.903 “Continuous Connectivity for Packet Data Users”u TR 25.876 “Multiple-Input Multiple Output Antenna Processing for

HSDPA”u TR 25.999 “HSPA Evolution beyond Release 7 (FDD)”u TR 25.820 (Rel.-8) “3G Home NodeB Study Item Technical Report”


Abbreviations

AICH Acquisition Indicator ChannelAMR Adaptive Multi-RateBPSK Binary Phase Shift KeyingCLTD Closed Loop Transmit DiversityCPC Continuous Packet ConnectivityCQI Channel Quality InformationDSL Digital Subscriber LineE-RACH Enhanced Random Access ChannelF-DPCH Fractional Dedicated Physical Control

ChannelGW GatewayHNB Home NodeBHOM Higher Order ModulationHSPA High-Speed Packet-AccessIA Intelligent AntennaLTE Long Term EvolutionMAC-ehs enhanced high-speed Medium Access

ControlMAC-i/is improved E-DCH Medium Access

ControlMIMO Multiple-Input Multiple-Output

Mux Multiplexing

PARC Per Antenna Rate Control

PCI Precoding Control Information

PDU Protocol Data Unit

Rx Receive

RTT Round Trip Time

SDU Service Data Unit

SAE System Architecture Evolution

S-CPICH Secondary Common Pilot Channel

SDMA Spatial-Division Multiple-Access

SINR Signal-to-Interference plus Noise Ratio

SISO Single-Input Single-Output

SM Spatial Multiplexing

Tx Transmit

VoIP Voice over Internet Protocol

16QAM 16 (state) Quadrature AmplitudeModulation

64QAM 64 (state) Quadrature AmplitudeModulation

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