Wcdma Hspa+ Principle [PDF]

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HSPA+ Principle

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HSPA+ Principle

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HSPA+ Principle

1

About This Course l

This course introduces principles and some key technologies of HSPA+.

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HSPA+ Principle

2

References l

3GPP Release 7 Specification References: p

3GPP TS 25.211: Physical channels and mapping of transport channels onto physical channels (FDD)

p

3GPP TS 25.212: Multiplexing and channel coding (FDD)

p

3GPP TS 25.213: Spreading and modulation (FDD)

p

3GPP TS 25.214: Physical layer procedures (FDD)

p

3GPP TS 25.308, "UTRA High Speed Downlink Packet Access (HSPDA); Overall description"

p

3GPP TS 25.309: FDD Enhanced Uplink

p

3GPP TS 25.301: Radio Interface Protocol Architecture

p

3GPP TS 25.302: Services provided by the physical layer

p

3GPP TS 25.321: Medium Access Control (MAC) protocol specification

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Contents 1. HSPA+ Overview 2. Key Technologies of HSPA+

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Contents 1. HSPA+ Overview 2. Key Technologies of HSPA+

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HSPA+ Introduction l

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.

l

HSPA+ (also known as HSPA evolution) is introduced in 3GPP Release 7. It is an enhancement to HSPA.

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HSPA+ Principle

6

Goals for HSPA+ in Release7 l

Reduced service delay

l

Increase peak data rates

l

Improve spectrum efficiency

l

Increase system capacity

l

Reduce UE power consumption

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HSPA+ Principle

7

Room to Improve Release 6 l

Release 6 (HSDPA and HSUPA) already provides high-speed wireless access to large number of users.

l

But there is room for even more improvements: p

Use of multiple antenna techniques (MIMO) to increase peak data rate and system capacity

p

Higher order modulation scheme to improve downlink spectral efficiency and peak data rate

p

Adapt system behavior to match application requirements to reduce interference and to extend UE battery life

p

Expand use of high speed HS-PDSCH channel beyond DTCH and DCCH, extend it to the CELL_FACH state.

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HSPA+ Principle

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HSPA+ Features in Release 7 l

Downlink enhanced L2

l

Downlink 64QAM

l

MIMO (Multiple Input Multiple Output)

l

Enhanced CELL_FACH operation

l

CPC (Continuous Packet Connectivity)

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DL 64QAM, MIMO, and Enhanced CELL_FACH must be used in combination with HSDPA and Enhanced L2. CPC must be used in combination with both HSDPA and HSUPA.

l

MIMO and DL 64QAM are used to achieve higher data rates.

l

CPC, enhanced CELL_FACH operation are used to achieve more efficient system operation.

Features dependencies:

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HSPA+ Principle

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MIMO and DL 64QAM l

MIMO p

MIMO increases transmission rates through space multiplexing and improves channel qualities through space diversity. The network side can dynamically select single- or dual-stream transmission according to channel conditions. The peak rate at the MAC layer can reach 28 Mbit/s.

l

DL 64QAM p

DL 64QAM allows the use of 64QAM in HSDPA to increase the number of bits per symbol and thus to obtain higher transmission rates. The peak rate at the MAC layer can reach 21 Mbit/s.

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MIMO and DL 64QAM can not be used simultaneously in Release 7.

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10

Enhanced CELL_FACH Operation l

Enhanced CELL_FACH operation p

Enhanced CELL_FACH operation allows the use of HSDPA technologies for the UEs in the CELL_FACH, CELL_PCH, and URA_PCH state. The purpose is to increase the peak rates in these states and reduce the signaling transmission delay during service setup or state transition with the result improving the user experience.

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RAN 11.0 supports HSDPA in only the CELL_FACH state.

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DL Enhanced L2 l

This feature allows Uu L2 to use flexible PDU size on RLC layer and segmentation on MAC layer. The feature prevents the L2 from becoming the bottleneck of higher Uu rate increased by MIMO and 64QAM.

l

DL enhanced L2 is the precondition of MIMO, 64QAM and enhanced CELL_FACH operation.

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12

CPC (Continuous Packet Connectivity) l

CPC allows the uplink and downlink transmissions to take place at periodic intervals. This feature reduces the transmitted power (and thus increases the UE battery life) because the UE does not have to monitor and transmit overhead channels every TTl. This reduction in the transmitted power also helps to increase the uplink capacity by decreasing the total interference. This improvement is especially significant when there are users who transmit data infrequently as VoIP users.

l

CPC feature consists of DL DRX, UL DTX and HS-SCCH less operation.

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DL DRX is discontinuous downlink reception.

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UL DTX is discontinuous uplink transmission.

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HSPA+ Principle

13

HSPA+ Capable UE Categories HS-DSCH category

Supported Modulations Without MIMO

Supported Modulations with MIMO

Category 13 Category 14

QPSK, 16QAM, and 64QAM

None

QPSK and 16QAM

QPSK and 16QAM

QPSK, 16QAM, and 64QAM

QPSK and 16QAM

Category 15 Category 16 Category 17 Category 18

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All such UEs must support DL Enhanced L2. These categories do not indicate whether CPC and Enhanced CELL_FACH operation are supported. During the connection setup procedure or the service setup procedure, the UE notifies the network of its capability to support these features.

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HSPA+ Principle

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Contents 1. HSPA+ Overview 2. Key Technologies of HSPA+

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Contents 2. Key Technologies of HSPA+ 2.1 Downlink Enhanced L2 2.2 Downlink 64QAM 2.3 MIMO 2.4 Enhanced CELL_FACH Operation 2.5 CPC

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HSPA+ Principle

16

Limitation of Original L2 Function l

MIMO and 64QAM increase the DL rates on the Uu interface. The original DL L2 function cannot adapt to such high rates. To prevent L2 from becoming the bottleneck of network performance, 3GPP Release 7 introduces enhancements to L2.

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The original L2 function uses fixed RLC PDU sizes. The typical fixed size is 336 or 656. This cannot meet the requirement of high-speed transmission for larger RLC PDU sizes. The peak date rate can be achieved by MIMO is 28Mbps and it is 21Mbps by 64QAM. However, small fixed RLC PDU will limit the maximum data rate with original L2 function. The following is a typical example:

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HSPA+ Principle

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Downlink Enhanced L2 in Release 7 l

Downlink enhanced L2 includes the following two features: p

Improving the RLC entity to support flexible RLC PDU sizes

p

Adding a new entity, the MAC-ehs, implementing data segmentation at the MAC layer, and supporting the multiplexing of multiple priority queues

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The difference between Release 6 L2 and Release 7 L2:

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HSPA+ Principle

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Flexible RLC PDU size l

With introduction of flexible RLC PDU sizes, the RLC layer will not segment higher-layer packets with sizes less than maximum RLC PDU size (the maximum RLC PDU size is configurable and maximum value is 1500 bytes). Thus, the RLC layer can flexibly adapt to variations in traffic volume and reduce the overhead of the RLC PDU header.

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HSPA+ Principle

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MAC-hs Entity (UTRAN side) in Release 6 MAC-d flows MAC-hs

Scheduling/Priority handling Priority Queue distribution

Priority Queue

Priority Queue

Priority Queue distribution

Priority Queue

Priority Queue

MAC – Control

HARQ entity

TFRC selection

Associated Uplink Signalling

HS-DSCH

Associated Downlink Signalling

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MAC-ehs Entity (UTRAN side) in Release 7 MAC-d flows MAC-ehs

Scheduling/Priority handling Priority Queue distribution

Priority Queue

Priority Queue

Priority Queue

Segme ntation

Segme ntation

Segme ntation

MAC – Control

Priority Queue MUX

HARQ entity TFRC selection

Associated Uplink Signalling

HS-DSCH

Associated Downlink Signalling

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MAC-ehs entity is introduced in Release 7 to replace MAC-hs entity to support HSPA+. Higher layer can configure which one is used. MAC-ehs and MAC-hs can not be used simultaneously. MAC-ehs can support segmentation and concatenation. MAC-ehs can choose to segment or concatenate data based on Uu interface channel condition. For example, when the channel conditions of the UE are poor (for example, on the cell edge), the MAC-ehs can segment the RLC PDU into smaller PDUs for transmission at lower rates to ensure the service continuity.

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HSPA+ Principle

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Contents 2. Key Technologies of HSPA+ 2.1 Downlink Enhanced L2 2.2 Downlink 64QAM 2.3 MIMO 2.4 Enhanced CELL_FACH Operation 2.5 CPC

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HSPA+ Principle

22

Modulation Modes for HSPA+ l

Three modulation modes can be used for HS-PDSCH

64QAM allows more bits per Symbol to be transmitted

Higher peak rate achieved in good channel condition

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Page22

HSPA+ can support three modulation modes: QPSK, 16QAM and 64QAM. Which mode is used is stilled based on the channel condition of UE. The AMC feature introduced with HSDPA enables adaptation of modulation and coding to varying radio conditions. To improve the advantages of AMC even further, a new modulation scheme, 64 QAM, is introduced with HSPA+. Theoretically 64QAM can provide a peak rate of 21 Mbit/s to a single UE. It enables the user with good channel conditions to download data at higher rates, improves user experience.

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HSPA+ Principle

23

CQI Mapping Table Change for 64QAM l

64QAM not configured

l

64QAM configured

CQI

TBS

Codes

Modula tion

CQI

TBS

Codes

Modula tion

1

137

1

QPSK

1

136

1

QPSK

…

… 25

14411

10

16-QAM

25

14424

10

16-QAM

26

17237

12

16-QAM

26

15776

10

64-QAM

27

21754

15

16-QAM

27

21768

12

64-QAM

28

23370

15

16-QAM

28

26504

13

64-QAM

29

24222

15

16-QAM

29

32264

14

64-QAM

30

25558

15

16-QAM

30

38576

15

64-QAM

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Additional CQI mapping tables have been added to cover the CQI mapping for the new UE categories. The example in the slide is for UE Category 14: p

The table on the left side is used when 64QAM is disabled.

p

The table on the right side is used when 64QAM is configured.

The upper range of the CQI values is mapped into modulation of 64QAM, with significant changes, while the rest of the table has limited changes only.

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HSPA+ Principle

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HS-SCCH Change for 64QAM l

Release 6

Channelization Code Set

l

Release 7 Channelization Code Set Last bit: 0:16QAM Last bit 1: 64QAM

Modulation Scheme 0: QPSK 1: 16QAM

Modulation Scheme 0: QPSK 1: QAM

MUX

MUX HS-SCCH part 1 Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.

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HS-SCCH part 1 Page24

In Release 7, three different types of HS-SCCH are available: type 1 (normal operation: no MIMO and no type 2), type 2 (HS-SCCH less operations), and type 3 (for MIMO operations). Type 1 is the format for downlink 64QAM. There is no change in redundancy version mapping. A few changes are necessary in physical layer for the HS-SCCH (type 1) to indicate the modulation format: p

p

Mapping of Modulation Scheme is now: ‘0’ stands for QPSK and ‘1’ stands for QAM. When 64QAM is configured, the last bit in Channelization Code Set is used to distinguish between 16QAM and 64QAM modulation format.

The remaining 6 bits of the CCS are used for the channelization code set information, 3 bits for the code group ID (as previous release), and 3 bits for the code offset ID (instead of the previous 4 bits, it means range is reduced when 64QAM is configured.). HS-SCCH part 2 is not affected by 64QAM. n

l

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HSPA+ Principle

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Prerequisites for Downlink 64QAM l

UE capability p

l

Service type p

l

UE category 13, 14, 17 and 18 can support downlink 64QAM.

64QAM modulation mode is only used for HSPDA service.

Cell capability p

The Serving cell must support downlink enhanced L2 and 64 QAM.

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By Uu interface signaling and Iub interface signaling RNC can get the UE capability and cell capability information for 64QAM. If both UE and the HSPA serving cell support 64QAM, it can be enabled. In Release 7, MIMO and downlink 64QAM can not be configured simultaneously. Downlink enhanced L2 must be supported as the prerequisite for downlink 64QAM. A UE category 19 shall be treated as category 17 and a UE category 20 shall be treated as category 18.

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Contents 2. Key Technologies of HSPA+ 2.1 Downlink Enhanced L2 2.2 Downlink 64QAM 2.3 MIMO 2.4 Enhanced CELL_FACH Operation 2.5 CPC

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HSPA+ Principle

27

What is MIMO? l

MIMO: Multiple Input Multiple Output

…

…

Transmitter

Wireless WirelessChannel Channel

Receiver

M

N Channel Condition Feedback

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In wireless communications, MIMO refers to a wireless channel with multiple inputs and multiple outputs. In a MIMO system, there are N*M signal paths from the transmit antennas and the receive antennas, and the signals on these paths are not identical.

l

3GPP Release 7 supports only 2×2 MIMO system.

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HSPA+ Principle

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What can MIMO provide? l

2×2 MIMO can increase peak data rate to 28Mbps Data Stream 1

Transmitter

Wireless WirelessChannel Channel

Receiver

Data Stream 2

Channel Condition Feedback

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Page28

For HSDPA, the peak physical layer throughput is14.4Mbps. To achieve 14.4 Mbps peak rate, all available SF-16 OVSF codes will be used. With MIMO system, the multiplexing gain is obtained with independent data streams on different antennas. The 2*2 MIMO system defined by 3GPP Release 7 can be 28Mbps.

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29

Effect of Channel Condition to MIMO l

MIMO operation is affected by channel condition of UE.

l

Only when the channel conditions are good, two parallel data streams can be carried in different transmitters. This is dualstream case. Otherwise only one data stream is carried even though two transmitters are used. This is single-stream case.

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In the dual-stream case, two MAC-ehs PDUs can be transmitted simultaneously in a TTI. After coding, the two streams are mapped onto the corresponding HS-PDSCHs with the same orthogonal code. In the single-stream case, only one MAC-ehs PDU is transmitted in a TTI, and using transmit diversity through two antennas can provide higher transmission qualities.

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HSDPA with MIMO in Release 7 l

Operation is similar to Release 5 HSDPA, but with different signaling: p

p

Via HS-DPCCH UE reports n

Channel Condition

n

Preferred antenna weight

n

Dual stream or single stream preference

Based on UE report, NodeB n

Determines number of data streams, TB size, modulation and coding scheme and antenna weighting

n

Informs UE of the decision via HS-SCCH

l

NodeB transmits the data via HS-PDSCH channel.

l

Upon receiving the data, UE sends ACK/NACK via HS-DPCCH.

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HSPDA MIMO operation in Release 7 is the same procedure as Release 5 HSDPA operation. The same control channels are used for both; however, the signaling carried on the control channels is different. The signaling formats on HS-SCCH and HS-DPCCH are changed to handle the additional information needed for MIMO operation. These changes includes: p

More feedback from UE: n

Channel Quality Indicator (CQI) is reported for both antennas

Antenna weighting vector is reported More signaling sent to UE supporting dual stream transmission n

p

n

Transport block (TB) sizes for each stream

n

Modulation and coding scheme for each stream

n

Antenna weighting vector used

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Illustration of 2×2 MIMO

Pilot for channel estimation

Pre-coding

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Page31

Actually MIMO is a closed-loop pre-coding mode. Based on UE feedback NodeB decides to transmit dual stream data (two transport blocks in one TTI) or single stream data (one transport block in one TTI). If dual stream data is transmitted, two streams are spread and scrambled independently. The spreading code for two streams are identical.

l

After spreading and scrambling the data streams are pre-coded. For dual streams precoding is used to make the two stream orthogonal. For single stream the pre-coding is just like transmit diversity.

l

On each antenna, a common pilot channel is transmitted. It is used for channel estimation. UE can monitor the two pilot channels to estimate the channel between NodeB and UE and then give feedback to NodeB.

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Pre-coding l

In single-stream case pre-coding is used to achieve transmit diversity. It is similar to closed-loop transmit diversity.

l

In dual-stream case pre-coding is used to reduce the interference between two streams and try to make them orthogonal.

l

Four predefined antenna weighting vectors are used, identified by PCI (Pre-coding Indicator). NodeB decides which weighting vector is used and inform UE.

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When transmitting the data, the NodeB decides which pre-coding vector to use, which may not be preferred by the UE. When one TB is sent: p

TB is called primary TB.

p

Vector (w1, w2) is used. w1 is fixed, 4 possible choices for w2

p

The chosen w2 is signaled on the HS-SCCH

When two TBs are sent: p

One TB is called the primary, the other is called the secondary TB.

p

Vector (w1, w2) is used for the primary TB. w1 is fixed, 4 possible choices for w2.

p

Vector (w3, w4) is used for the secondary TB. w3 is fixed, w4 is a function of w2.

p

The chosen w2 is signaled on the HS-SCCH

PCI

0

1

2

3

w1

1/ 2

1/ 2

1/ 2

1/ 2

w2

(1+j)/2

(1-j)/2

(-1+j)/2

(-1-j)/2

w3

1/ 2

1/ 2

1/ 2

1/ 2

w4

-(1+j)/2

-(1-j)/2

-(-1+j)/2

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-(-1-j)/2

HSPA+ Principle

33

Pilots for Channel Estimation l

On each antenna, a common pilot channel is transmitted. It is used to estimate the channels between NodeB and UE.

l

In 2×2 MIMO mode the channel between transmitter and receiver can be expressed as the following format, where hi,j is the estimate of the channel between the physical antenna i at the base station and the antenna j at the UE.

h1,1 h1,2  H =  h h  2,1 2,2  Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.

Page33

l

Supposing pilots are P. UE can receive P’. So the relationship between P and P’ is P ’ = PH.

l

P is predefined and P’ is received by UE. So UE can estimate the result of H.

l

Two pilots in different antennas have different formats, they are just like the following figure is a example:

Antenna 1

00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

Antenna 2

11 11 00 00 11 11 00 00 11 00 11 11 00 00 11 11 00 00 11 11 00 00 11 11 slot #14 Frame#i

slot #0

Frame Boundary

slot #1 Frame#i+1

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34

HS-DPCCH Signaling l

UE reports on HS-DPCCH p

p

p

Preferred number of transport blocks n

2 TBs = dual stream transmission

n

1 TBs = single stream transmission

Channel Quality Indicator (CQI) n

Type A: provide CQI for each TB when 2 TBs are preferred

n

Type B: provide CQI when only one TB should be sent

Preferred pre-coding (Pre-coding Control Indication: PCI) n

p

Indicate 1 of 4 predefined pre-coding vectors

ACK/NACK n n

n

If one TB was transmitted, UE sends one ACK or NACK If two TBs were transmitted, UE reports one out of four possible values for ACK/ACK, ACK/NACK, NACK/ACK, NACK/NACK Each TB is acknowledged independently.

Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.

l

UE measures pilot signals from two transmit antennas. Based on this, the UE indicates the following: p

Preferred number of TBs in one TTI according to current channel

p

Preferred pre-coding

p

CQI

l

UE send a composite PCI/CQI report on HS-DPCCH.

l

NodeB decides:

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p

Whether one or two TBs are scheduled

p

Which modulation scheme and TBs to use for each

p

Which pre-coding to use

When two TBs are sent, the one with higher modulation (if different) will be the primary one. The NodeB signals the pre-coding and the number of TBs on HS-SCCH. UE independently ACK/NACKs each transmitted TB.

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35

Two Types of CQI Feedback l

Two types of CQI is reported by UE: type A and type B

l

In type A report, UE indicates:

l

p

Preferred pre-coding vectors (2 bits)

p

Preferred number of TBs per TTI

p

CQI (8 bits) n

“Old” 31-level CQI report, if one TB is preferred

n

“New” 255-level CQI report, if two TBs is preferred

In type B report, UE indicates: p

Preferred pre-coding vectors (2 bits)

p

CQI (5 bits)

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l

Type A CQI reports are constructed using a CQI value that is computed according to:

15 x CQI1 + CQI 2 + 31, 0 ≤ CQI 1 / 2 < 15 CQI =  0 ≤ CQI S < 31  CQI S l

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when 2 transport blocks are preferred by the UE when 1 transport block is preferred by the UE

Type A CQI value greater than 30 indicates that 2 TBs are preferred, while type A CQI value smaller than 31 means that 1 TB is preferred. NodeB configures UE to use N type A reports every period of M CQI reports. UE uses type B reports in remaining time. The following figures are two examples for type A/B CQI reporting:

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Two Types of CQI Feedback (continued) l

NodeB Configures UE to use N type A reports every period of M CQI reports. UE uses type B in remaining time.

l

The following are two examples for type A/B reporting:

Type A

Type A

Type A

Type A

Type B

Type A

Type A

Type A

Type A

Type B

Time

Configuration N/M = 4/5, CQI feedback cycle = 1 (2ms) Type A

Type A

Type B

Time

Configuration N/M = 2/3, CQI feedback cycle = 4 (8ms) Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.

l

Page36

When the UE reports both type of CQI, the network gets complete channel condition information for both single and dual stream transmission. The network can then schedule single or dual stream as appropriate for the UE and the system.

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HS-SCCH Signaling – Part 1 l

New HS-SCCH format Part 1 p

Transmitted in the first slot of the 3-slot HS-SCCH TTI

p

Supports single stream (8 bits) or dual streams (12bits)

p

For dual stream operation (12 bits) n

Channelization code set (7 bits)

n

Modulation Scheme and number of TBs (3 bits)

n

Pre-coding vector (2 bits)

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Page37

If two TBs are transmitted in one TTI, both TBs are transmitted using the same set of OVSF codes.

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HS-SCCH Signaling – Part 2 l

Transmitted in the second and third slots of the HS-SCCH TTI

l

Supports single stream (12 bits) or dual stream (20 bits)

l

For dual stream transmission (20 bits): p

Transport block size (6 bits per TB)

p

HARQ IDs (4bits)

p

Redundancy version (2 bits per TB)

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39

Prerequisites for MIMO l

UE capability p

l

Service type p

l

UE category 15, 16, 17, 18, 19 and 20 can MIMO

MIMO modulation mode is only used for HSPDA service.

Cell capability p

The Serving cell must support downlink enhanced L2 and MIMO.

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l

l

Page39

By Uu interface signaling and Iub interface siganlling RNC can get the UE capability and cell capability information for MIMO. If both UE and the HSPA serving cell support MIMO, it can be enabled. In Release 7, MIMO and downlink 64QAM can not be configured simultaneously. Downlink enhanced L2 must be supported as the prerequisite for MIMO. A UE category 19 shall be treated as category 17 and a UE category 20 shall be treated as category 18.

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Contents 2. Key Technologies of HSPA+ 2.1 Downlink Enhanced L2 2.2 Downlink 64QAM 2.3 MIMO 2.4 Enhanced CELL_FACH Operation 2.5 CPC

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Purpose of Enhanced CELL_FACH Operation l

The RRC states of a UE in connected mode include CELL_DCH, CELL_FACH, CELL_PCH, and URA_PCH. HSPA significantly increases the maximum achievable uplink and downlink data rates, but only for UEs in CELL_DCH states.

l

The purpose of the Enhanced CELL_FACH feature is to extend the use of HSDPA function to the CELL_FACH, CELL_PCH, and URA_PCH state as well, allowing a more flexible allocation of resources, increased data rates, and reduced transmission delays. So far RAN11 only supports HSDPA in CELL_FACH.

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Benefits of Enhanced CELL_FACH Operation l

UE can reduce the state transitions from CELL_FACH to CELL_DCH

l

UE can receive high speed downlink traffic (data or signaling) in CELL_FACH.

l

UL transmission is still possible in CELL_FACH and uplink traffic (data or signaling) is carried on RACH. (as in Release 6)

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l

l

l

Page42

In Releases prior to Release 7, the data and signaling of the UE in the CELL_FACH state are carried on the FACH. The resources of the channel cannot be allocated flexibly and the transmission rates are limited. In Release 7, the data and signaling ( BCCH, CCCH, DTCH, and DCCH ) of the UE in the Enhanced CELL_FACH state can be carried on the HS-DSCH. The HSDPA reception in CELL_FACH state requires the UE to support MAC-ehs.

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Logical Channel Mapping in Enhanced CELL_FACH DTCH

DCCH

FACH

HS-DSCH

RAN10

RAN11

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l

l

BCCH

CCCH

Page43

In RAN10 the data and signaling ( BCCH, CCCH, DTCH, and DCCH ) of the UE in CELL_FACH state are carried on the FACH. In RAN11 the data and signaling ( BCCH, CCCH, DTCH, and DCCH ) of the UE in the Enhanced CELL_FACH state can be carried on the HS-DSCH.

l

The mapping from BCCH to HS-DSCH is used only to send the SYSTEM INFORMATION CHANGE INDICATION message. The real broadcast system information is still mapped to PCCPCH (BCH).

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UE Reception in Enhanced CELL_FACH l

UE can decode HS-SCCH using: p

Dedicated H-RNTI (from prior dedicated RRC signaling)

p

Or an H-RNTI selected from list of common H-RNTI in SIB5

l

UE use HS-SCCH channelization code from SIB5.

l

UE decodes HS-PDSCH to receive DL data transmissions. p

l

BCCH/CCCH/DTCH/DCCH

No Uplink ACK/NACK or CQI is transmitted.

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l

l

Page44

When UE receive HS-PDSCH channel in enhanced CELL_FACH state, it can not receive SCCPCH (FACH) simultaneously. UE in enhanced CELL_FACH state does not report ACK/NACK to NodeB. NodeB must perform blind retransmissions of HSDPA data in the downlink.

l

UE does not report CQI to NodeB. The measurement result on RACH can be used for link adaption.

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State Transition – Idle to CELL_FACH/CELL_DCH l

UE procedures in state transition from idle to CELL_FACH/CELL_DCH 1. Read system information in SIB5 2. Sends an RRC Connection Request on PRACH to request PS service 3. Selects an H-RNTI from common H-RNTI listed, HS-SCCH channelization code from SIB5. 4. Monitor HS-SCCH using selected common H-RNTI. n

Decode HS-PDSCH to receive RRC Connection Setup.

5. Transitions to CELL_FACH or CELL_DCH based on the reconfiguration message. n

Uses new assigned H-RNTI for further HS-PDSCH reception.

6. May receive subsequent data in CELL_FACH or CELL_DCH

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Page45

When the UE enters Connected Mode from Idle Mode by sending an RRC Connection Request message, it starts listening to the HS-SCCH indicated in SIB5. Detection of HSSCCH is based on the common H-RNTI listed in SIB 5. The UE selects the common H-RNTI to be used for reception of the RRC Connection Setup message in the HS-PDSCH.

l

After detecting the HS-SCCH with common H-RNTI, the UE begins reception of the corresponding HS-PDSCH TTI. The UE may enter CELL_FACH or CELL_DCH. When entering CELL_FACH from Idle Mode, the RRC Connection Setup Message should include a new HRNTI and C-RNTI for the UE to use for further HS-DSCH reception. When entering CELL_DCH from Idle Mode, the RRC Connection Setup Message should include a new HRNTI for the UE to use for further HS-DSCH reception.

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Contents 2. Key Technologies of HSPA+ 2.1 Downlink Enhanced L2 2.2 Downlink 64QAM 2.3 MIMO 2.4 Enhanced CELL_FACH Operation 2.5 CPC

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47

CPC Motivation l

CPC allows packet data users to remain in CELL_DCH state to a larger extent, thus avoiding frequent packet connection reestablishments.

l

CPC motivation is mainly to allow more efficient use of continuous packet data connections: p

Higher capacity

p

Lower UE battery consumption

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48

What is CPC? l

l

CPC adds three main features: p

UL DTX (discontinuous uplink transmission)

p

DL DRX (discontinuous downlink reception)

p

HS-SCCH less operation

These three features are optional p

UL DTX can be used alone or in combination with other CPC features.

p

DL DRX can be used only if UL DTX is used.

p

HS-SCCH less operation can be used alone or in combination with other CPC features.

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49

Preconditions for CPC Configuration l

UE is in CELL_DCH state.

l

No DCH is configured.

l

Downlink traffic is carried by HS-DSCH and uplink traffic is carried by E-DCH.

l

SRB (Signaling radio bearer) is carried by HSPA.

l

F-DPCH is configured.

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l

l

Page49

The DCH cannot be configured in the uplink or downlink. The E-DCH must be configured in the uplink, and the HS-DSCH and F-DPCH must be configured in the downlink. Signaling and data must be carried on HSPA channels. So CPC is dependent on SRB over HSDPA and SRB over HSUPA.

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Basic Concepts of UL DTX l

UL DTX includes the following features: p

UL DPCCH DTX

p

E-DCH transmission restriction

p

CQI reporting DTX

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Page50

UL DPCCH DTX: The UL DPCCH is transmitted whenever E-DCH or HS-DPCCH is transmitted. When UE is not transmitted data on E-DCH or HS-DPCCH, the UE shall not transmit UL DPCCH except for a shot burst periodically (based on configuration parameters).

l

l

E-DCH transmission restriction: RNC can configure UE to restrict the start of E-DCH transmission to coincide with UL DTX intervals, if there has been no E-DCH transmission for a configurable number of TTI. CQI reporting DTX: If configured by the RNC, the CQI on HS-DPCCH can be transmitted in the HS-DPCCH subframes when the CQI reporting period defined transmission overlaps with DPCCH DTX transmission.

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UL DPCCH DTX

Release 6 UL DPCCH

Release 7 UL DPCCH DTX

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l l

Page51

A basic UL DTX feature is UL DPCCH DTX If there is no uplink data transmission, UE can stop continuous UL DPCCH transmission and regularly transmit a DPCCH burst to maintain power control signalling and link synchronisation. In this mode UE can save power and reduce uplink interference.

l

UL DPCCH DTX is activated/deactivated via RRC or layer 1 message.

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52

UL DPCCH DTX Activation/Deactivation l

UL DPCCH DTX activation and deactivation UL DTX deactivated

UL DTX enabled

Y

Enabling_delay elapse

UL DTX Configured in RRC?

DTX activation order

DTX deactivation order

UL DTX Active DTX at UE_DTX_cycle_1 (Initial state)

N

Data to transmit

No E-DCH data for Inactivity_threshold_for _UE_DTX_cycle_2 TTIs

No UL DTX DTX at UE_DTX_cycle_2

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l

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Page52

After UL DTX parameters are sent received in some RRC messages (RRC Connection Setup/Radio Bearer Setup etc.), UL DPCCH DTX is enabled, but it will be activated only after Enabling_Delay radio frames. When UL DTX is active, two transmission periods can be defined for UL DPCCH DTX. They are UE_DTX_cycle_1 (shorter) and UE_DTX_cycle_2 (longer) depending on E-DCH inactivity. This enables the UL DPCCH transmission rate to autonomously adapt to data transmission activity: for higher data activity, UL DPCCH can be configured for more frequent transmission; and for lower data activity, DPCCH can be configured for less frequent transmission. This increase DTX gain.

l

NodeB can also deactive/active UL DTX by sending order on HS-SCCH.

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UL DPCCH DTX Operation l

When UL DTX is active: p

p

UE shall transmit the uplink DPCCH in a slot if there is: n

HARQ-ACK/NACK transmission on HS-DPCCH

n

CQI transmission on HS-PDSCH

n

E-DCH transmission

Otherwise, UL DPCCH shall be transmitted based on: n

Two periodic (DTX_cycle) transmission gaps

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UL DPCCH DTX Operation (continued) l

Two cycles of UL DPCCH DTX

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Page54

Generally, the UE uses cycle 1 for UL DTX. If the UE has no data to transmit for a longer time, the UE uses cycle 2 for UL DTX. When there is data to transmit, the UE uses cycle 1 again.

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55

CQI Reporting DTX l

CQI reporting DTX Normal CQI reporting CQI feedback cycle

Does not coincide with UE_DTX_cycle No CQI reporting

DPCCH additional transmissions (When CQI is transmitted)

UE_DTX_cycle Last HS-DSCH activity on the downlink

CQI DTX timer

CQI DTX timer expires

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Page55

UL DTX can perform CQI DTX. p

If DL data is inactive for a configurable time, UE can stop sending periodic CQI reports, unless overlapping with UL DPCCH DTX bursts. In this mode UE can save power can reduce uplink interference.

l

If UL DTX is active, the UE shall transmit CQI base on the following rules: p

After every HS-SCCH/HS-PDSCH decoding: n

p

CQI reports have higher priority than the UL DPCCH DTX bursts.

n CQI is sent every CQI feedback cycle, as Release 6 After CQI_DTX_TIMER subframes of DL inactivity (HS-PDSCH)

n

CQI is sent only when overlapping with UL DPCCH DTX bursts

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E-DCH transmission restriction l

UL DTX supports configurable E-DCH transmission start time restrictions p

It can enable DRX at NodeB to save NodeB processing power. After data inactivity, UE shall wait next MAC_DTX_cycle for sending E-DCH data

MAC_Inactivity_Threshold MAC_DTX_cycle

E-DCH data to send but not sent

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l

l

Page56

RNC can configure UE to restrict the start of E-DCH transmission, which is also called EDCH DTX. The rule of MAC E-DCH DTX is: p

After last E-DCH transmitted TTI:

p

If there has been no E-DCH transmission for MAC_Inactivity_Threshhold TTI:

p

E-DCH data shall be transmitted only at given times (every MAC_DTX_cycle subframes). Whenever UE transmits one E-DCH TTI, the UE can transmit E-DCH data as long as n

data inactivity is shorter than MAC_Inactivity_Threshold TTIs.

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Basic Concepts of DL DRX l

DL DRX feature is designed to save UE battery.

l

If UL DTX is configured, RNC can also configure DL DRX. p

p

UE can receive the following channels discontinuously: n

HS-SCCH and HS-PDSCH

n

E-AGCH and E-RGCH

When DRX is configured, RNC will send DL data (on HS-SCCH and HS-PDSCH) only at pre-defined periodic intervals.

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DL DRX Activation/Deactivation l

DL DRX activation and deactivation Y

UL DTX and DL DRX Configured in RRC?

N No DL DRX

DL DRX deactivated

DTX/DRX enabled Enabling_delay elapse

DRX activation order

DRX deactivation order

DL DRX Active NO DRX (Initial state) No HS-SCCH/HS-PDSCH reception during Inactivity_threshold_for_UE _DRX_cycle subframes DRX at UE_DRX_cycle

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l

l l

l

Page58

Configuration and activation/deactivation rules for DL DRX are similar as for UL DTX. DRX is configured/enabled using the same RRC messages that configure DTX and will be activated (DL DRX active state) only after Enabling_delay frames. Different with UL DTX, DL DRX has only one cycle which is UE_DRX_cycle. Inactivity_threshold_for_UE_DRX_cycle defines additional successive subframes where NodeB can transmit unrestricted. NodeB can also deactive/active UL DTX by sending order on HS-SCCH.

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DL DRX Operation l

If DL DRX (and UL DTX) is configured and supported by UE: p

UE shall continue to receive F-DPCH and E-HICH as normal operation.

p

UE can apply DRX to HS-SCCH and HS-PDSCH. n

If UE has not received an HS-SCCH or HS-PDSCH subframes during the last Inactivity_Threshlod_for_UE_DRX_cycle subframes, UE shall monitor HS-SCCH and HS-PDSCH every DRX_cycle frames.

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DL DRX Operation (continued) Inactivity_threshold_for_UE _DRX_cycle

UE_DRX_cycle

subframe subframe subframe subframe subframe subframe subframe subframe subframe

HS-SCCH

UE doesn’t monitor HS-SCCH/HS-PDSCH

subframe subframe subframe subframe subframe subframe subframe subframe subframe

HS-PDSCH UE shall monitor continuously HS-SCCH/HS-PDSCH

UE shall monitor HS-SCCH/HSPDSCH every UE_DRX_cycle only

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l

l

Page60

When DL DRX is not active, UE shall continuously monitor and receive all downlink physical channels. When DL DRX is active, UE shall continue to receive F-DPCH as required, and the UE does not need to receive physical downlink channels other than the F-DPCH, except for the following cases: p

UE shall receive E-HICH frame corresponding to an E-DCH transmission.

p

UE shall monitor the HS-SCCH subframes in HS-SCCH and HS-PDSCH (if scheduled) periodically.

p

UE has received an HS-SCCH and HS-PDSCH (if scheduled) during the last Inactivity_Threshold_for_UE_DRX_cycle subframes.

p

UE shall monitor E-AGCH transmission from the serving E-DCH cell.

p

UE shall monitor E-RGCH transmission.

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E-AGCH and E-RGCH Monitoring l

UE can apply DRX to E-AGCH and E-RGCH p

There are two main RRC parameters to control E-AGCH and E-RGCH DRX: Inactivity_Threshold_for_UE_Grant_Monitoring and UE_DRX_Grant_Monitoring.

l

UE can avoid monitoring E-AGCH and E-RGCH channels except for the following case: p

A scheduled E-DCH transmission has been performed in any of Inactivity_Threshold_for_UE_Grant_Monitoring previous TTIs.

p

UE_DRX_Grant_Monitoring is TRUE and the start of E-AGCH or E-AGCH transmission overlaps with an HS-SCCH subframe.

p

E-AGCH and E-RGCH commands overlap with an E-HICH corresponding to a scheduled E-DCH transmission.

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Basic Concepts of HS-SCCH Less Operation l

Under certain conditions (for example low data rate), HSPDSCH (only for first transmission) can carry data without associated HS-SCCH.

l

With HS-SCCH less operation, DL OVSF codes and power can be saved for low data rate downlink transmission.

Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.

l

Page62

HS-SCCH less operation mechanism enables the following features: p

p

p

The first transmission of small transport blocks on predefined HS-DSCH is performed without the accompanying HS-SCCH. HARQ retransmissions of the first HS-DSCH transmission are accompanied by HSSCCH. HARQ is limited to two retransmissions and the redundancy version is pre-defined.

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HS-SCCH Less Operation l

If HS-SCCH less operation is configured by RRC, UE shall behave as follows: p

UE monitors one or two pre-assigned HS-PDSCH codes every TTI n

p

HS-PDSCH CRC is generated based on UE specific H-RNTI.

UE performs a blind decoding of HS-PDSCH, trying some predefined transport block sizes.

p

The modulation mode can only be QPSK. n

Suitable for low data rate transmission

Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.

l l

l

l

Page63

The modulation mode can only be QPSK. It is suitable for low data transmission. Only four predefined TB formats for MAC-hs PDU are allowed. These formats information will be informed to UE in RRC signaling. At most two predefined HS-PDSCH OVSF codes are assigned per UE. Which OVSF codes are used will also be informed to UE in RRC signaling. HS-PDSCH CRC is UE specific so UE knows that whether the data belongs to it.

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HS-SCCH Less Operation (continued) HS-SCCH carries •Pointer to previous transmission •Retransmission number •Transport format •Channelization codes for HS-PDSCH HS-SCCH first transmission

first retransmission

second retransmission

HS-DPSCH blind decoding HS-DPCCH ACK

NACK NACK not transmitted Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.

l

l

Page64

If UE can decode the first transmission successfully, it sends ACK to NodeB on HS-DPCCH. If UE can not decode the first transmission, it buffers the data but doesn’t send NACK. In HS-SCCH less operation mode, the HARQ retransmissions of HS-PDSCH are accompanied by HS-SCCH.

l

HS-SCCH used for HS-SCCH less operation is type 2. It carries the following information for retransmissions: p

An indication that this is a retransmission of a previous HS-SCCH less operation.

p

Whether the retransmission is the first retransmission or the second retransmission.

p

p

The channelization codes and the transport block size used by the retransmission data. A pointer to the previous transmission attempt the retransmission should be soft combined with.

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CPC Coexistence with Other HSPA+ Features Feature

UL DTX

DL DRX

HS-SCCH less

UL DTX

N/A

Compulsory

Possible

DL DRX

Possible

N/A

Possible

HS-SCCH less

Possible

Possible

N/A

HSDPA

Compulsory

Compulsory

Compulsory

HSUPA

Compulsory

Compulsory

Possible

F-DPCH

Compulsory

Compulsory

Compulsory

MIMO

Possible

Possible

Not supported

DL 64 QAM

Possible

Possible

No supported

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Page65

l

Possible means combination of the features is valid but not mandatory.

l

Compulsory means combination of the features is mandatory.

l

Not supported means combination is not valid.

l

N/A means not applicable.

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66

Thank you www.huawei.com

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