HSPA & HSPA+ Introduction

Transcription

1 HSPA & HSPA+ Introduction

2 Objectives Upon completion of this course, you will be able to: Understand the basic principle and features of HSPA and HSPA+ Page1

3 Contents 1. HSPA & HSPA+ Overview 2. HSDPA Introduction 3. HSUPA Introduction 4. HSPA+ Introduction Page2

4 UMTS Data Rate Evolution GSM GPRS WCDMA R99 HSDPA R5 HSUPA R6 HSPA+ R7 HSPA+ R8 EDGE DL 64QAM MIMO 16QAM DL 64QAM+MIMO DC-HSDPA Mobile Network Uplink Peak Data Rate Downlink Peak Data Rate GSM 9.6Kbps 9.6Kbps GPRS 20Kbps 40Kbps EDGE 60Kbps 120Kbps WCDMA Release Kbps 384Kbps HSDPA Release 5 384Kbps 14.4Mbps HSUPA Release Mbps 14.4Mbps HSPA+ Release Mbps 28Mbps HSPA+ Release Mbps 42Mbps Page3

5 High Speed Downlink Packet Access What are the benefits of HSDPA Higher Data Rates Peak data rate up to 14Mbps per user (Release 5) Higher Capacity More subscribers and throughput Further reduces the cost per megabyte Richer Application Low latency improvement for streaming,interactive, background applications Page4

6 Release 99 Downlink Packet Data How is Packet Data handled in Release 99 (FDD)? DCH ( Dedicated Channel ) Spreading codes assigned per user Closed loop power control Soft handover Node B FACH ( Common Channel ) Common Spreading code No closed loop power control No soft handover Node B Page5

7 Release 99 Downlink Limitation Dedicated Channel Features ( DCH ) Maximum implemented downlink of 384kbps OVSF code limitation for high data rate users Rate change according to burst throughput is slow Outer loop power control responds slowly to channel Common Channel Features ( FACH ) Good for burst data application Only low data rates supported Fixed transmit power Page6

8 HSDPA Basic Concepts Set of high data rate channel Channels are shared by multiple users Each user may be assigned all or part of the resource every 2ms Big shared pipe Code multiplexing for HSDPA HSDPA user#1 HSDPA user#2 HSDPA user#3 HSDPA user#4 2ms a set of HS-PDSCHs Node B Page7

9 HSDPA Basic Concepts (cont.) How will HSDPA figure out the limitations of R99 Adaptive modulation and coding Fast feedback of Channel condition QPSK and16qam Channel coding rate from 1/3 to 1 Multi-code operation Multiple codes allocated per user Fixed spreading factor NodeB fast Scheduling Physical Layer HARQ ( Hybrid Automatic Repeat request ) Page8

10 Comparison between R99 and HSDPA Mode DCH FACH HSDPA Channel Type Dedicated Shared Shared Power Control Closed Inner Loop at 1500Hz & Closed Outer Loop No Fixed Power with link adaptation Soft Handover Supported Not Supported Not Supported Suitability for Bursty Poor Good Good Data Rate Medium Low High Page9

11 High Speed Uplink Packet Access Driver force for HSUPA Data Rate demand for higher peak data rates in uplink Qos lower latency Capacity better uplink throughput Coverage better uplink coverage for higher data rate Page10

12 Release 99 Uplink Packet Data DCH (Dedicated Channel) Variable spreading factor Closed loop power control Macro diversity (soft handover) RACH Common spreading code Fixed spreading factor No closed loop power control No soft handover Page11

13 Release 99 Uplink Limitation Large scheduling delay Radio resource is controlled from RNC Uplink DCCC (Dynamic channel configuration control) Large latency Transmission time interval duration of 10/20/40/80ms RNC based retransmission in case of errors (RLC layer) Limited uplink data rate Deployed peak data rate is 384kbps with limited subscriber number Page12

14 HSUPA Basic Concepts E-DCH channel has been introduced Interference is shared by multiple users NodeB controls all UEs data rate with fast scheduling E-DCH Page13

15 Improved Characters by HSUPA Higher peak data rate in uplink Reduced latency Faster retransmission to improve throughput Fast scheduling Optimize the resource allocation to maximize the total throughput Quality of Service support Improve QoS control and resource utilization Page14

16 HSPA+ Introduction 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. HSPA+ (also known as HSPA evolution) is introduced in 3GPP Release 7 and develops continuously in the following Release. It is an enhancement to HSPA. Page15

17 Goals for HSPA+ Reduced service delay Increase peak data rates Improve spectrum efficiency Increase system capacity Reduce UE power consumption Page16

18 Contents 1. HSPA & HSPA+ Overview 2. HSDPA Introduction 3. HSUPA Introduction 4. HSPA+ Introduction Page17

19 HSDPA Key Techniques Block 1 Block 1 Block 2 Block 1? Block 1 AMC (Adaptive Modulation & Coding) Data rate adapted to radio condition on 2ms + Block 1? HARQ(Hybrid ARQ)with Soft combing Reduce round trip time Fast Scheduling based on CQI and fairness Scheduling of user on 2ms SF16, 2ms and CDM/TDM Dynamic shared in Time and code domain 16QAM 16QAM in complement to QPSK for higher peak bit rates 3 New Physical Channels Page18

20 Adaptive Modulation and Coding AMC ( Adaptive Modulation and Coding ) in accordance with CQI ( Channel Quality Indicator ) Adjust data rate to compensation channel condition Good channel condition higher data rate Bad channel condition lower data rate Adjust channel coding rate to compensation channel condition Good channel condition channel coding rate is higher e.g. 3/4 Bad channel condition channel coding rate is lower e.g. 1/3 Adjust the modulation scheme to compensation channel condition Good channel condition high order modulation scheme e.g. 16QAM Bad channel condition low order modulation scheme e.g. QPSK Page19

21 Adaptive Modulation and Coding (cont.) AMC ( Adaptive Modulation and Coding ) based on CQI ( Channel Quality Indicator ) CQI ( channel quality indicator ) UE measures the channel quality and reports to NodeB every 2ms or a longer cycle NodeB selects modulation scheme,data block size based on CQI Power Control Rate Adaptation Bad channel condition More power Node B Good channel condition less power Bad channel condition low data rate Good channel condition high data rate Node B Page20

22 CQI mapping table for UE category 10 CQI value Transport Block Size Number of HS-PDSCH Modulation 0 N/A Out of range Reference power adjustment QPSK QPSK QPSK QPSK QPSK QAM QAM QAM QAM QAM QAM 0 Page21

23 HSDPA UE Categories HS-DSCH Category Maximum Number of HS-DSCH Codes Received Minimum Inter-TTI Interval Maximum Number of Bits of an HS-DSCH Transport Block Received Within an HS- DSCH TTI Total Number of Soft Channel Bits Category Category Category Category Category Category Category Category Category Category Category Category Page22

24 Hybrid Automatic Repeat ReQuest Conventional ARQ In a conventional ARQ scheme, received data blocks that can not be correctly decoded are discarded and retransmitted data blocks are separately decoded Hybrid ARQ ( HARQ ) In case of Hybrid ARQ with soft combining, received data blocks that can not be correctly decoded are not discarded. Instead the corresponding received signal is buffered and soft combined with later received retransmission of information bits. Decoding is then applied to the combined signal Page23

25 Hybrid Automatic Repeat ReQuest (cont.) Illustration of HARQ: The use of HARQ with soft combining increases the effective received Eb/Io for each retransmission and thus increases the probability for correct decoding of retransmissions, compare to conventional ARQ Page24

26 HARQ Combining There are many different schemes for HARQ with soft combining In case of Chase combining ( CC ) each retransmission is an identical copy of the original transmission In case of Incremental Redundancy ( IR ) each retransmission may add new redundancy Page25

27 HARQ Process Each HSDPA assignment is handled by a HARQ process runing in NodeB and UE The UE HARQ process is responsible for: Attempting to decode the data Deciding whether to send ACK or NACK Soft combining of retransmitted data The NodeB HARQ process is responsible for: Selecting the corrected bits to send according to the selected retransmission scheme and UE capability Page26

28 Short TTI (2ms) Shorter TTI ( Transmission Time Interval ) is to reduce RTT ( round trip time ) Shorter TTI is necessary to benefit from other functionalities such as AMC, scheduling algorithm and HARQ Page27

29 Shared Channel Transmission In HSDPA, a new DL transport channel is introduced call HS- DSCH A part of the total downlink code resource is dynamically shared between HSDPA and Release 99 Page28

30 Power Sharing for Channel Transmission A part of the total downlink power resource is dynamically shared between HSDPA and Release 99 Power margin for DCH power control Total Power Allowed power for HSDPA Higher power utility efficiency DPCH Power for CCH Time Page29

31 Resource Allocation Resources are assigned to HSDPA user only when they are actually to be used for transmission, which leads to efficient code and power utilization Page30

32 Higher-Order Modulation Scheme HSDPA modulation scheme QPSK 16QAM: 16QAM can provide higher peak rate Page31

33 Fast Scheduling Fast scheduling is about to decided to which terminal the shared channel transmission should be directed at any given moment Scheduler may be based on: Channel condition Amount of data waiting in the queue Fairness (Satisfied users) Cell throughput, etc Some basic scheduling algorithms: Round Robin (RR) Maximum C/I (MAX C/I) Proportional Fair (PF) Enhanced Proportional Fair (EPF) Page32

34 HSDPA New Physical Channels Page33

35 HSDPA Channel Mapping DCCH DTCH HS-DSCH HS-PDSCH HS-SCCH HS-DPCCH Page34

36 Theoretical HSDPA Maximum Data Rate Theoretical HSDPA Maximum data rate is 14.4Mbps How do we get to 14.4Mbps? Multi-code transmission NodeB must allocate all 15 OVSF codes ( SF =16 ) to one UE Consecutive assignments using multiple HARQ process NodeB must allocate all time slots to one UE UE must decode all transmission correctly on the first transmission Low channel coding gain Effective code rate = 1 Requires very good channel conditions to decode 16QAM Requires very good channel condition Page35

37 A Example of Calculating HSDPA Data Rate Try to calculate the HSDPA data rate assuming 5 OVSF code for HS-PDSCH Consecutive assignment QPSK Turbo code rate =1/3 Retransmission 75% of data block decoded on first transmission 25% of data block decoded on second transmission Page36

38 Contents 1. HSPA & HSPA+ Overview 2. HSDPA Introduction 3. HSUPA Introduction 4. HSPA+ Introduction Page37

39 HSUPA Key Technology Overview HSUPA key technologies 2ms TTI Lower SF Fast L1 HARQ New Channels Fast scheduling Improved Cell Capacity Higher Peak Data Rate Lower Latency Improved QoS Support Fast Resource Scheduling Page38

40 HSUPA vs. HSDPA HSDPA HSUPA New high-speed shared channel Dedicated channel with enhanced capabilities HARQ with fast retransmission at layer 1 Rate/modulation adaptation Single serving cell Fast NodeB scheduler Shared NodeB power and code Fast power control Soft handover Fast NodeB scheduler Rise-over-Thermal (ROT) Page39

41 Rise-over-Thermal Noise In order to decode received data correctly, the uplink interference shall be controlled. Rise-over-Thermal is a measure of the uplink load. NodeB monitors uplink interference and tells UE how much power can be used to transmit uplink data. Page40

42 NodeB Scheduler for HSUPA The HSUPA scheduler considers the trade-off between the following two points: Several users those want to transmit at high data rate all the time Satisfying all requested grants while preventing overloading and maximizing resource utilization Page41

43 HSUPA Operation The UE sends a transmission request to the NodeB for getting resources. The NodeB responds to the UE with a grant assignment, allocating uplink band to the UE. The UE uses the grant to select the appropriate transport format for the Data transmission to the NodeB. The NodeB attempts to decode the received data and send ACK/NACK to the UE. In case of NACK, data may be retransmitted. UE 1. REQUEST 2. GRANT 3. DATA 4. ACK/NACK NodeB Page42

44 HSUPA Operation (continued) 1. Transmission Request The UE request data transmission by the scheduling UE Buffer UE Power information (SI), which is determined according to the UE power and buffer data UE availability. The scheduling information is sent to the NodeB. Scheduling Information (SI) Page43

45 HSUPA Operation (continued) 2. Grant Assignment The Node B determines the UE grant by monitoring RoT SI Satisfaction uplink interference (RoT at he receiver), and by considering the UE transmission requests NodeB and level of satisfaction. The grant is signaled to the UE by new grant channels. GRANT Page44

46 HSUPA Operation (continued) 3. Data Transmission The UE uses the received grant and, based on its power and GRANT UE Power UE Buffer data availability, selects the E- DCH transport format and the corresponding transmit power. UE Data are transmitted by the UE on together with the related control information. Data and related control information Page45

47 HSUPA Operation (continued) 4. Data Acknowledgment The NodeB attempts to decode the received data and indicates to the UE with ACK/NACK. If no ACK is received by he UE, the data may be retransmitted. Data and related control information NodeB ACK/NACK Page46

48 New Channels for HSUPA Uplink Transport Channel E-DCH: Carries high speed uplink data Uplink Physical Channels E-DPDCH: Carries E-DCH E-DPCCH: Carries control signal for E-DPDCH Downlink Physical Channels E-HICH: Carries HARQ ACK/NACK indicator for E-DCH E-RGCH: Carries relative grant determined by the scheduler E-AGCH: Carries absolute grant determined by the scheduler Page47

49 HSUPA Channel Mapping DCCH DTCH E-DCH E-DPDCH E-DPCCH E-HICH E-AGCH E-RGCH Page48

50 New Channels in HSUPA Operation 1. The UE sends a request for resources. The request includes status of its data buffers and is sent on E-DPDCH. 2. Based on the request from the UE, the Node B allocates a resource grant to the UE. The grant is sent on the E-AGCH channel. 3. This grant can be modified by the Node B every TTI using the E-RGCH channel. 4. The UE transmits data on E-DPDCH. Control information needed to decode the data is sent on E-DPCCH. 5. The Node B decodes the received packet and informs the UE whether it could decode the data successfully or not on the E-HICH channel. 1 E-DPDCH E-AGCH E-HICH E-DPCCH E-RGCH Page49

51 HSUPA Features Shorter TTI of 2ms In HSUPA both 10ms TTI and 2ms TTI are supported. A shorter TTI allows reduction of the latency and increasing the average and peak cell throughput. Higher Peak Data Rate For a 10-ms TTI UE, peak data rate is limited to 2 Mbps. Higher peak data rates can be achieved with a 2ms TTI UE 5.76Mbps is the maximum peak data rate for HSUPA. Page50

52 HSUPA Features (continued) Hybrid-ARQ N-channel stop-and-wait protocol, with 4 HARQ processes for 10ms TTI and 8 HARQ processes for 2ms TTI Synchronous retransmission Separate HARQ feedback is provided per radio link. Page51

53 E-DCH Active Set and Mobility Support There are three different types of radio links in the UE E-DCH active set: Serving E-DCH Cell: The cell from which UE receives AGCH. Serving E-DCH RLS: Set of cells that contain at least the serving cell and from which the UE can receive RGCH No-Serving RL: Cell that belongs to the E-DCH active set but not belong to the serving RLS and from which the UE can receive a RGCH. Serving E-DCH cell Non-Serving E-DCH Radio Link (RL) Serving E-DCH Radio Link Set (RLS) Page52

54 Theoretical HSUPA Maximum Data Rate How to get 5.76Mbps: Lower channel coding gain Effective code rate = 1 Requires very good channel conditions to decode Lower spreading factor UE uses SF 2 Multi-code transmission UE uses 4 codes, 2 with SF2 and 2 with SF4 2ms TTI Page53

55 E-DPDCH with SF4 and Puncturing Maximum payload for spreading factor of 4, TTI of 2 ms and coding rate of 1 is 1920 bits and the corresponding data rate is 960kbps bits payload 1920 systematic 1920 parity 1920 parity R = 1/3 Turbo Coding 1920 symbols 1920 modulation symbols 7690 chips Puncturing BPSK Modulation SF=4 2ms Page54

56 Lower Spreading Factor SF2 Maximum payload for spreading factor of 2, TTI of 2 ms and coding rate of 1 is 3840 bits and the corresponding data rate is 1920kbps bits payload 3840 systematic 3840 parity 3840 parity R = 1/3 Turbo Coding 3840 symbols 3840 modulation symbols 7690 chips Puncturing BPSK Modulation SF=2 Page55

57 Multi-code Transmission For one UE in HSUPA operation, up to 4 E-DPDCH can be used simultaneously, two using SF4 and two using SF2. Use of 4 codes transmission 2*SF2 + 2*SF4: (2*1920kbps) + (2*960kbps) = 5760kbps Page56

58 HSUPA UE Capabilities E-DCH Max number Minimum Supported Peak rate Peak rate category of E-DPDCH channels SF TTI for TTI = 10MS for TTI = 2ms Category 1 1 SF4 10ms 711kbps -- Category 2 2 SF4 2&10 ms 1448kbps 1448kbps Category 3 2 SF4 10ms 1448kbps -- Category 4 2 SF2 2&10 ms 2000kbps 2886kbps Category 5 2 SF2 10ms 2000kbps -- Category 6 4 SF2 2&10ms 2000kbps 5742kbps Page57