MobileComm Technologies India Pvt. Ltd. Dallas . Atlanta . Washington . LA . Sao Paulo . New Delhi . Toronto . Muscat. SydneyHSDPA BASIC

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HSPA Motivations

3G Enables Wider Options of Services

3G Enables Advanced Data Services

HSPA for Higher Speed

Data Rate Demand for higher peak data rates Delay Lower latency Capacity Better capacity and throughput Better spectrum efficiency Finer resource granularity Coverage Better coverage for higher data rateWhat are the requirements for HSPA?

UMTS Data Rate Evolution

Uplink Peak Data Rate (Typical Deployment)Downlink Peak Data Rate (Typical Deployment)GSM9.6 kbps9.6 kbpsGPRS20 kbps40 kbpsEDGE60 kbps120 kbpsWCDMA Release 99 64 kbps 384 kbpsHSDPA - Release 5 384 kbps10 Mbps*HSUPA - Release 61.4 Mbps (early deployment)10 Mbps

Applications Benefiting from HSPA

Voice-over-IP (VoIP)- Low latency, Quality of Service (QoS) control, fine resource granularity and improved capacityVideo Telephony (in Packet Switched domain)- Low latency, Quality of Service (QoS) control, high data rates and improved coverage and capacityGamingLow latency, fast resource allocation

Video Share / Picture Share- High Uplink data rates and improved coverage and capacityFile Uploading (large files)- High Uplink data rates and improved coverage and capacity

UMTS Evolution / 3GPP ReleasesYear19992001matured GSM/GPRS CN+ UTRAN+ WCDMA Air Interfaceup to 384 kbps (2 Mbps) Bearer independent CS CN CAMEL Phase 4 UTRA FDD repeater low chip rate TDD mode HSDPA (14 Mbps) IMS Phase 1 W-AMR enhanced Location Services 1800/1900 MHz HSUPA (5.76 Mbps) IMS Phase 2 WLAN-Interworking MBMS Push-services2002/032005

HSPA Motivation and General Principle

Improved performance and spectral efficiency in DL and UL by introducing a shared channel principle:Significant enhancement with peak rates up to 14.4 Mbps in DL, and 2 Mbps in ULHuge capacity increase per site; no site pre-planning necessaryImproved end user experience: reduced delay/latency, high response time

HSDPA Basic

What is High Speed Downlink Packet Access (HSDPA)Smooth Upgrade Short time to market with existing sites

HSDPAWhat is HSDPA?A UMTS packet air interface3.6 Mbps up to theoretical 14.4 Mbps peak/userAdd-on solution on top of 3GPP R99/R4 architectureHSDPA terminals co-exist with R99 terminalsNo modification to the Core Network & Traffic Classes

Difference between HSDPA and WCDMA today?More Content for High End Users (5x faster and lower latency of 150 ms)More Data Users per Cell (because it is ~10x more spectrally efficient)

Adaptive Modulation and Coding (AMC) - Depending on UE channel conditions (CQI) - QPSK, 16QAM - Coding rate (1/4 - 3/4) - Data rate adapted on 2 ms time basis Fast Retransmission - Hybrid Automatic Repeat reQuest (HARQ) - UE soft-combines data - Reduced RTT Fast Packet Scheduling (PS) Scheduling of users on 2 ms time basis New radio channels included for HSDPA - DL: HS-(P)DSCH, HS-SCCH - UL: HS-DPCCH It is important to note that downlink HSDPA is a shared data channel - End user throughput depends on the number of the other users on the same HSDPA cell - Capacity planning and dimensioning of HSDPA is different to non-real time (NRT) DCH bearer Introduction HSDPA Basics

HSDPA Basic Principles

Dynamic Power Allocation

Dedicated channels (power controlled)Common channelsPower usage with dedicated channelstUnused powerPower3GPP Release 993GPP Release 5 Dedicated channels (power controlled)Common channelsPower usage with dedicated channelstUsed for HSDPAPower

Shared Channel Transmission Up to 15 codes (SF16) can be allocated and shared between the users. It also depends on what the UE can support. A set of radio resources dynamically shared among multiple users, primarily in the time domain.

C1,0 = [1]C2,1 = [1-1]C2,0 = [11]C4,0 = [1111]C4,1 = [11-1-1]C4,2 = [1-11-1]C4,3 = [1-1-11]C8,0 = [11111111]C8,1 = [1111-1-1-1-1]C8,2 = [11-1-111-1-1]C8,3 = [11-1-1-1-111]C8,4 = [1-11-11-11-1]C8,5 = [1-11-1-11-11]C8,6 = [1-1-111-1-11]C8,7 = [1-1-11-111-1]C16,0 = [.........]C16,1 = [.........]C16,15 = [........]C16,14 = [........]C16,13 = [........]C16,12 = [........]C16,11 = [........]C16,10 = [........]C16,9 = [.........]C16,8 = [.........]C16,7= [.........]C16,6 = [.........]C16,5 = [.........]C16,4 = [.........]C16,3 = [.........]C16,2 = [.........]SF = 1248SF = 16256512...Multi Code OperationShared Channel Transmission

CQI Channel Quality IndicatorUE sends CQI info in the UL to aid rate adaptation and scheduling

CQI (1-30) provides the Node B with a measure of the UE's perceived channel quality and the UE receiver performance

The CQI report estimates the number of bits that can be transmitted to the UE using a certain assumed power with a block error rate of 10%

Node BCQI (Report periodically)

Fast Link Adaptation

Rate controlAdjusts data rate based on the Radio conditions (CQI)Fast Adaptation : 2 ms TTI basisAdaptive Modulation (QPSK and 16 QAM) and CodingUse available power

Fast Hybrid ARQ with Soft CombiningHARQFor Fast retransmissions

Fast Hybrid ARQ with Soft CombiningDuring retransmission, the UW employs soft combining.1st Decoding in UE2nd Decoding in UEFinal Picture

HSPA BasicsFast Scheduling in the Time domain (1):Transmission Time Interval (TTI) of 2ms assigned to usersA short TTI reduces round-trip time and improves the tracking of channelvariationsthe length of HSDPA sub-frame (TTI) is 3 slots (7680 chips) Fast Schedulingin the Node-BFast Channel-dependent Scheduling

Slot #0

Slot#1

Slot #2

T

slot

= 2560 chips, M*10*2

k

bits (k=4)

Data

N

data

1

bits

1 HS

-

PDSCH subframe: T

f

= 2 ms

HSPA BasicsFast Scheduling in the Time domain (2):Transmission is based on:Channel QualityUE CapabilitiesCurrent load in the cell (available resources / buffer status)Traffic Priority classes / QoS classesUE Feedback (ACK/NACK)Fast Scheduling in the code DomainUp to 15 codes in parallel per TTIFast Schedulingin the Node-BFast Channel-dependent Scheduling

Queue Selection AlgorithmsRound Robin RR:Assigns sub-frames in rotation User at cell edge served as frequently as user at cell centre

Doesnt account for UEs channel conditions Low total throughput in cell

If no data have to be transferred to certain UE then sub-frame assigned to next UEProportional Fair PF:Takes into account multipath fading conditions experienced by UEImproved total throughput in cell compared to RR

Sub-frames assigned according scheduling metricRatio instantaneous data rate / average data rate experienced in the pastUser at cell edge served less frequently as user at cell centre

HSPA BasicsHigh Order modulation: 16QAMCode Multiplexing: up to 15 codes in parallelUser can be code and time multiplexed (TTI= 2ms)

CodesTTI = 2msUser 1User 2User 3Time and Code multiplexing in HSDPAFixed Spreading Factor, SF=16-> 3.84Mcps/16 = 240 K symbols/s-> @ 16QAM -> 240 x 4 = 960 kbps-> @ code rate = 3/4 -> 720 kbps720 kbps bit rate can be achieved per code -> 10.8 Mbps over 15 codesAdaptive Modulation & Coding (AMC)

AIRCOM International 2006Adaptive Modulation & Coding (AMC)16 QAM allows twice the data rate to a user compared to QPSK

Currently all R99 channels use QPSK

16 QAM will only be possible for users within a limited radius of the NodeB (

AIRCOM International 20062msTTI 0TTI 1TTI 2TTI 3TTI 4TTI 5etcTimeNumber of allocated codes50Adaptive Modulation & Coding (AMC)

AIRCOM International 2006

AIRCOM International 2006Coding is used to protect the user data bits from errorsHSDPA has a very flexible coding scheme which can vary every 2ms and between each user This allows a much more varied distribution of data rates within a cellHigher rates in very good radio conditions near the NodeBHigher rates compared to R99 on cell edgeAdaptive Modulation & Coding (AMC)

AIRCOM International 2006

AIRCOM International 2006UE Support for AMCMaximum data rate possible to a single user depends heavily on the UE they are usingThere are 12 categories defined in the standards for different levels of HSDPA support

CategoryCodesInter-TTIModulationData rate153QPSK/16QAM1.2 Mbps253QPSK/16QAM1.2 Mbps352QPSK/16QAM1.8 Mbps452QPSK/16QAM1.8 Mbps551QPSK/16QAM3.6 Mbps651QPSK/16QAM3.6 Mbps7101QPSK/16QAM7.2 Mbps8101QPSK/16QAM7.2 Mbps9151QPSK/16QAM10.2 Mbps10151QPSK/16QAM14.4 Mbps1152QPSK only0.9 Mbps1251QPSK only1.8 Mbps

The big picture for HSDPAAdditional capacitySoftware upgradeAdditional capacityCore NetworkHLRRNCNode BBackhaulAdditional backhaul bandwidth to support higher data ratesIncreased processing power (HW)RF power allocation to HSDPA (min,max)Management of new device categories & signalling ch.Software upgrade Extended QoS field for HSDPA devices (for data rates >8 Mbps)

HSPA BasicsSummary of HSDPA key benefitsThroughputs of :Up to 3.6 Mbps with QPSKUp to 14 Mbps with 16QAMAdapted to variable-throughput flowsQuicker response timeMix of HSDPA and dedicated traffic possible on same carrierCost effectiveHigh Speed Downlink Packet AccessAdapted to burstytraffic (statisticalMultiplexing benefit)

Fabricio Martinez

AIRCOM International 2006HSDPA LimitationsHSDPA does not respond for the following needsHigh uplink speed (uploading, video calls, video conferences, browsing, online gaming, E-commerce)Large capacity (Limited number of users)Limited coverage (WCDMA has lower coverage than GSM in rural areas WCDMA infrastructure is not profitable)

POSSIBLE SOLUTIONS: HSUPA significantly improved uplinkWiMAX significantly improved capacityCDMA2000 increased coverage

Fabricio Martinez

AIRCOM International 2006

HSDPA Channels

Physical Channel OverviewHS-PDSCHHigh-Speed Physical DL Shared ChannelHS-SCCHHigh Speed Shared Control Channelassociated DCHDedicated Channel (Rel. 99)HS-DPCCHHigh Speed Dedicated Physical Control ChannelNode BMAC-hsF-DPCHFractional Dedicated Physical Channel (Rel. 6/7)

HS-PDSCHSF= 1SF= 2SF= 4SF= 8SF=16Example: Allocated for HS-DSCHallocated for other channelsHS-PDSCH: High-Speed Physical Downlink Shared Channel Transfer of actual HSDPA data 5 - 15 code channels QPSK or 16QAM modulation 2 ms TTIs Fixed SF16

HS-SCCHHS-SCCH: High-Speed Shared Control ChannelL1 Control Data for UE; informs the UE how to decode the next HS-PDSCH frame e.g. UE Identity, Channelisation Code Set, Modulation Scheme, TBS, H-ARQ process informationFixed SF128transmitted 2 slots in advance to HS-PDSCHsNSN implementation with slow power control: shares DL power with the HS-PDSCHmore than 1 HS-SCCH required when Code Multiplexing is usedUp to 4 HS-SCCHs CodesTBS: Transport Block SizeSF16HS-PDSCHTimeUser 1User 2User 3User 4Subframe2 ms51015

HS-DPCCHUL HS-DPCCH: High-Speed Dedicated Physical Control ChannelMAC-hs Ack/Nack information (send when data received)Channel Quality Information (CQI reports send every 4ms, hardcoded period)Fixed SF 256HARQ-ACK(10 bit)1 Slot = 2560 chip2 Slots = 5120 chipSubframe # 0Subframe # iSubframe # N1 HS-DPCCH Subframe = 2ms CQI (20 bit)Channel Quality IndicationCQI values = 0 (N/A), 1 .. 30; steps: 1;1 indicating lowest, 30 highest air interface quality

HS-DPCCH & CQIUE observesP-CPICH (Ec/Io) CQI** UE internal (proprietary) processTB Size [bit]CQI value 0: N/A (Out of range) = Reference Power Adjustment (Power Offset) [dB]CQI used for: Link Adaptation decision Packet Scheduling decision

ACK/NACK used for: H-ARQ process Link Adaptation decision HS-SCCH power adaptationCQI TB Size # codes Modulation up to 15 HS PDSCHsP-CPICHHS DPCCH (ACK; CQI)HS SCCH

11371QPSK021731QPSK032331QPSK043171QPSK053771QPSK064611QPSK076502QPSK087922QPSK099312QPSK01012623QPSK01114833QPSK01217423QPSK01322794QPSK01425834QPSK01533195QPSK0163565516-QAM0174189516-QAM0184664516-QAM0195287516-QAM0205887516-QAM0216554516-QAM0227168516-QAM0239719716-QAM02411418816-QAM025144111016-QAM026144111216-QAM-127144111216-QAM-228144111216-QAM-329144111216-QAM-430144111216-QAM-5

Associated DCH (DL & UL)DL DPCH: Associated Dedicated Physical ChannelTransfer of L3 signalling messagesSpeech - AMRPower control commands for associated UL DPCH

UL DPCH: (DPDCH & DPCCH)Transfer of L3 signalling messagesTransfer of UL data 16 / 64 / 128 / 384 kbps, e.g. TCP acknowledgementsSpeech - AMR

DPDCH / DPCCH (time multiplexed)DPDCH: L3 signalling; AMRDPCCH: TPC for UL DPCH power controlDPDCH: L3 signalling, AMR; TCP ACKs; 16 / 64 / 128 348 kbpsDPCCH: TPC, Pilot, TFCI

Fractional DPCH: F-DPCH (DL)The Fractional DPCH (F-DPCH): was introduced in 3GPP Rel. 6 replaces the DL DPCCH when the DL DPDCH is not present, i.e. both application data and SRB are transferred using HSDPA includes Transmit Power Control (TPC) bits but excludes TFCI & Pilot bitsTFCI bits - no longer required as there is no DPDCHPilot bits - no longer required as TPC bits are used for SIR measurements increases efficiency by allowing up to 10 UE to share the same DL SF256 channelisation code time multiplexed one after another

Tx OffTPCSlot #i1 time slot 2560 chipsTx Off256 chips

HSPA mobilityHSDPASoft handover on associated DCH channels (signalling, UL data)Serving cell change for HSDPA data channelConnected only to one cell at a time

HS-SCCHHS-PDSCHDPCHDPCHServing HS-DSCH cellNotice that soft/softer handover is not supported for HS-SCCH/HS-PDSCH

* | HSPA BasicsComparison with R99 DCH and R5 HSDPA

Channel

DCH (R99)

HSDPA (R5)

Channel Type

Dedicated

Shared

Spreading Factor

Variable

Fixed (SF =16)

L1- H-ARQ

No

Yes

Multicode transmission

Possible

Yes

TTI length (ms)

40 / 20 / 10

2

Adaptive Modulation

No

Yes

Node B Scheduling

No

Yes

Fast Power Control

Yes

No

Soft Handover

Yes

No

Thank You

*HSDPAHSDPA stands for High Speed Downlink Packet Access. As the name suggests, this is a piece of UMTS functionality designed to deliver downlink packet data at very high data rates. It is a release 5 feature. It achieves its aim by using the following techniques:Use of shared channel concept Rather than constantly allocating and deallocating dedicated channels to individual users, users share a high bandwidth channel the HS-DSCH (High Speed Downlink Shared Channel). This allows the system to operate with a fat pipe

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