Huawei Dual Cell HSDPA Technology White Paper V1[1].0(20100128)

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Huawei DualCell HSPA Technology

White Paper

Issue V1.0

Date 2011-05-30

HUAWEI TECHNOLOGIES CO., LTD.

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

No part of this document may be reproduced or transmitted in any form or by any means without

prior written consent of Huawei Technologies Co., Ltd.

Trademarks and Permissions

and other Huawei trademarks are trademarks of Huawei Technologies Co., Ltd. All other

trademarks and trade names mentioned in this document are the property of their respective

holders.

Notice

The information in this document is subject to change without notice. Every effort has been made in

the preparation of this document to ensure accuracy of the contents, but all statements, information,

and recommendations in this document do not constitute the warranty of any kind, express or

implied.

Huawei HSPA+ White Paper

V1.0 (2011-05-30) Commercial in Confidence of 21

Contents

1 Executive Summary ............................................................................................................ 4

2 DC-HSDPA Introduction .................................................................................................. 5

3 DC-HSDPA Working Principle ....................................................................................... 8

3.2 Network Enhancements for DC-HSDPA ............................................................................................. 9

3.3 DC-HSDPA Channel Mapping ........................................................................................................... 10

3.4 Affect on CPC operations in DC-HSDPA .......................................................................................... 11

3.5 DC-HSDPA deployment with MIMO ................................................................................................ 11

4 DC-HSDPA Key Benefits ................................................................................................ 13

4.1 Improve User Expereience & Network Performance ......................................................................... 13

4.2 Easy Deployment and Low Cost ........................................................................................................ 14

5 Huawei DC-HSDPA Solution Highlights ................................................................... 16

5.1 Software upgraded Network Elements ............................................................................................... 16

5.2 Multi Carrier Transceivers ................................................................................................................. 17

5.3 Advance RRM and Schedulling Methods .......................................................................................... 17

6 Conclusion .......................................................................................................................... 19

7 Acronyms and Abbreviations ......................................................................................... 20



1 Executive Summary

In similarity with Long Term Evolution (LTE), the HSPA technology is also

influenced by the carrier aggregations. The performance and throughputs of

HSPA can also be improved by using multi-carrier bandwidth operations with or

without the adoption of multi transmission techniques. The end users’ throughputs

thus can be double or more as compared to single carrier HSPA. In addition, the

adoption of multi carriers in HSPA can bring similar peak throughput

performances as are achieved by MIMO techniques without changing the

hardware infrastructure of the network.

The first phase of multi-carrier HSPA based on 3GPP R8 standards uses two

consecutive carriers in the downlink to transmit data for one subscriber and

named as Dual Cell HSDPA (DC-HSDPA). The 3GPP R9 and beyond standards

specify the usage of more than two carriers for a single subscriber without the

restrictions of same frequency bands usage.

In 3GPPR8-based HSPA+, it is an optional choice for the operators to select

DC-HSDPA or MIMO. However, in later 3GPP standards the DC and MIMO

could be deployed together. In this paper, we will only focus on the DC-HSDPA

technology, its performance, deployment strategy and comparison with MIMO

according to the 3GPP R8 standards.

DC-HSDPA improves the end users’ throughput in the whole cell area even in the

cell edges and provides the quality of service for all users. Beside the bandwidth

cost, the evolution from the legacy HSPA to HSPA+ is easy and economical with

DC-HSDPA as compared to the network up-gradation by MIMO only. If

transceiver elements support multi carrier technology then no additional

hardware will be required for network up-gradation to DC-HSDPA.

.



2 DC-HSDPA Introduction

The use of multi carrier technology is defined by 3GPP Release 8 and further

improved in the later releases. The standard roadmap of multi carrier HSPA

technology is given in Figure 2-1. .

Figure 2-1 – 3GPP Standard Releases for DC-HSDPA

As a first step of multi carrier HSPA technology, Dual Cell HSDPA (DC-HSDPA)

is allowed for downlink only with some restrictions on carrier selection and

frequency band, or example:

1) The dual cell transmission will only apply to HSDPA physical channels

2) The two cells must belong to the same Node-B and are on adjacent carriers

3) The two cells shall not use MIMO to serve a single UE but two cells can be configured

as MIMO along with DC

4) The two cells must operate in the same frequency band

5) The UE will only communicate with one cell in the uplink

DC-HSDPA sector and carrier configuration topology is given Figure 2-2.



Figure 2-2 DC-HSDPA cell structure and working principle

Through dual cell transmission and having double radio resource, DC-HSDPA is

able to provide higher data throughput to the end users and better results can be

obtained in the cell edges.

One of the two cells is treated as anchor (primary) cell and the other one as

supplementary (secondary) cell and both of them can be deployed with equivalent

and non-equivalent channel configuration.

Figure 2-3 – Equivalent and non- equivalent deployment of Primary and Secondary cells

In equivalent deployment, both the cells can work as anchor and supplementary

cells for the dedicated subscribers in the same coverage area. Few of the

subscribers will treat one cell as their anchor cell and rest of them will treat

second as their anchor cell. The selection of the anchor carrier is based on cell

load and operators Radio Barer (RB) strategy. The anchor carrier always

initializes the handover process of an end user and supplementary carrier is not

involved in handover process. In additions, both the cells will work as an

independent single cell source for the non-DC-HSDPA subscribers or legacy

HSDPA subscribers. In non-equivalent deployment, the supplementary cell is

configured with one HS-DSCH and a P-CPICH; in this case, the supplementary

cell cannot serve traditional HSDPA, HSUPA and R99 users in standalone

operations. In both equivalent and non-equivalent deployment, the legacy HSDPA



service will not be interrupted after the introduction of DC-HSDPA in the

network.

_________________________________________________________________

Note:

Huawei strongly recommend Equivalent Deployment configuration and all the details in this

document are based on equivalent deployment configuration.

_________________________________________________________________

The implementations of DC-HSDPA along with 64QAM provide 42Mbps

theoretical DL peak throughput similar to 64QAM+MIMO based on 3GPP R8,

which is many times higher as compared to single cell HSDPA. Figure 2-4 shows

the peak data throughput comparison between single carrier and dual carrier for

16QAM and 64QAM modulated signals.

Figure 2-4 – Throughput comparison between single cell and dual cell HSDPA



3 DC-HSDPA Working Principle

The DC-HSDPA adopts carrier aggregation phenomena and use two 5 MHz carriers for a

single user’s data in the downlink. The Timing of the two cells remains the same and in

uplink, DC UE only connects to the anchor carrier. The ACK/NACK/CQI for second carriers

is Joint-encoded and reported by HS-DPCCH in anchor carrier. DC-HSDPA+MIMO is not

implemented within 3GPP R8 standards, but the sector can support DC and MIMO

simultaneously. The air interface architecture along with common requirements for

DC-HSDPA is given in Figure 3-1.

Figure 3-1 – Overview of DC-HSDPA working phenomena

Both the network and user equipment require up-gradation for the implementation of

DC-HSDPA. The network need to support joint scheduling and the UE need to support two

transport channels and HARQ entities.



3.2 Network Enhancements for DC-HSDPA

The implementation of DC-HSDPA is achieved by upgrading network at RLC and MAC

layer. Joint scheduling is implemented in the NodeB for the anchor and supplementary cell

that brings the scheduling gain and improves the data throughput for the end user. In NodeB,

MAC-d PDU is segmented in small frames for the implementation of joint scheduling and

data from RLC layer can be sent to more than one cell’s scheduler.

Figure 3-2 –DC-HSDPA downlink data flow process

The main benefit of segmenting MAC-d PDU in NodeB is to enable the network to send user

data to more than one MAC-ehs PDU of different cells.

The DC-HSDPA requires MAC-ehs entity and one MAC-ehs support HS-DSCH transmission

in more than one cell served by the same NodeB. The scheduler decides the data transmission

on each HS-DSCH channel. Each of the HS-DSCH is served by the separate HARQ entities.

The detail description of NodeB logical architecture for DC-HSDPA is given in Figure 3-3.



Figure 3-3 – Logical Architecture and data flow of DC-HSDPA in NodeB

MAC-ehs

MAC – Control

HS-DSCH

Priority Queue distribution

Associated Downlink

Signalling

Associated Uplink

Signalling

MAC-d flows/ MAC-c flows

Priority Queue

Scheduling/Priority handling

Priority Queue

Priority Queue

Segmentation

Segmentation

Segmentation

Priority Queue MUX

HS-DSCH

TFRC selection

Associated Downlink

Signalling

Associated Uplink

Signalling

HARQ entity

TFRC selection

HARQ entity

After the joint scheduling of two cells, the single user data is sent on separate HS-DSCH

through separate HARQ, which improves the users’ throughput and increase user experience.

The DC-HSDPA UE has to support two HS-DSCH transport channel, each HS-DSCH will

served by one HARQ entity.

3.3 DC-HSDPA Channel Mapping

In downlink, DC-HSDPA UE receives two HS-DSCH transport channels from two cells of

the same NodeB. Each transport channel maps one HSCCH and a HS-PDSCH physical

channel. All dedicated physical control channels DPCCH, DPCH/F-DPCH in Uplink and

downlink are carried on anchor carrier.

Figure 3-4 – DC-HSDPA Channel Mapping

As the uplink, DC is not a part of in 3GPP R8 dual cell solution, so the uplink DCH/E-DCH

channels of DC-HSDPA are only carried on anchor carrier. Single cell UE monitors



maximum 4 HS-SCCH on one frequency cell but DC-HSDPA UE monitors maximum 6

HS-SCCH on dual cell.

The UE feedbacks two CQI and HARQ ACK/NACK messages by HS-DPCCH channel to

the anchor carrier.

Figure 3-5 – HS-DPCCH Slot format for HSDPA-R5 and DC-HSDPA

HS-DPCCH uses a new frame format that enables it to carry CQI and HARQ ACK/NACK

information of two frequency cells in single TTI. In case, if the secondary frequency is not

activated for a user, the uplink feedback channel frame format and the information on

HS-DPCCH will be the same as in Release 5 HSDPA.

3.4 Affect on CPC operations in DC-HSDPA

Continuous Packet Connectivity (CPC) function can be enabled in the dual cell HSDPA but

with the following limitations:

CPC DTX is only applied on primary cell because there will be no uplink control

channel for the DC UE on secondary cell

CPC HS-SCCH Less Operation is limited on primary carrier.

Where as the UE will have the CPC DRX state on two carriers similar to the single cell

operation

3.5 DC-HSDPA deployment with MIMO

DC-HSDPA cells can also be configured as MIMO enabled functions and both the features

can run at the same time but only one service can be available for each user. Two types of cell

configuration can be used for DC-MIMO combined deployment:

1. MIMO on Independent Carrier

In this scheme, MIMO is given a separate carrier and DC-HSDPA will not be affected

by MIMO. The handover procedure is adopted for MIMO users to use third carrier for

MIMO only. Figure 3-6 shows configuration of configuration of DC-MIMO scheme 1.



Figure 3-6 – Scheme 1 for DC-MIMO combined cell Configuration

2. DC-MIMO on same Carrier

MIMO based carrier is combined with another carrier to service as DC-HSDPA in this

scheme. R99 is configured on a dedicated carrier because of more requirements and

more demands of voice users. Figure 3-7 shows the configuration of configuration of

DC-MIMO scheme 2

Figure 3-7 – Scheme 2 for DC-MIMO combined cell configuration



4 DC-HSDPA Key Benefits

DC-HSDPA is an alternative of MIMO to improve the data throughput and users’ experience

in HSPA+ based on 3GPP R8 standard. The carrier aggregation process enables the increase

in capacity and user throughput.

Regardless of double frequency requirements, a number of benefits from DC-HSDPA

attracting the mobile operators to chose it as a key feature. The key benefits are improved

user experience, easy deployment and low network cost.

4.1 Improve User Expereience & Network Performance

DC-HSDPA provide higher throughput to the end-users even they are far from the transceiver.

The data rate at the end of the cell can be maintained balance to support QOS service. The

coverage performance of a DC user is higher than every other HSPA user.

Figure 4-1 DC-HSDPA service coverage comparison with other HSPA users

DC-HSDPA is has best performance for the burst services like http, gaming or small size

download files. The burst services consume a small amount of resource and users’

transmission time is small, therefore; DC-HSDPA cells can easily share their resources to all



the subscribers. Multi-user response time is improved by 50% as compared to single carrier

for as long as the air interface is not congested.

Figure 4-2 – Response Gain Time of DC-HSDPA vs SC-HSDPA for Burst Services

However, on the other side, for the full buffer services like ftp files or heavy files where the

required data transmission is continuous and download time is long, the gain of DC-HSDPA

is impacted by the number of users. The gain in this condition will only improved from 10 to

20% of the single carrier if the number of subscribers reaches to 16 or more in a cell.

Figure 4-3 – DC-HSDPA Cell Gain for Full Buffer services

4.2 Easy Deployment and Low Cost

For a deployed network, it is easy to upgrade it for the DC-HSDPA, no new antenna

configuration and no new transceivers required for DC-HSDPA. The cells only need software

configuration for DC-HSDPA if the network is already operating on the multi frequency



configurations in a same coverage area. For the areas where the cell is covered by one carrier

frequency only, there will be new requirement for another carrier and it will cost some extra

amount.

In overall, the cost of extra antenna system, new transceivers and deployment cost is saved

by upgrading the network to DC-HSDPA.

Figure 4-4 – Up-gradation from SC-HSDPA to DC-HSDPA

The up-gradation process is very smooth and the performance of non-DC users will not be

degraded after the up-gradation of cell to the DC-HSDPA. All the legacy UEs will provide

the similar throughput as before in the single cell and there will be no service degradation

effect.



5 Huawei DC-HSDPA Solution Highlights

Huawei is one of the key contributors in DC-HSDPA standard development and technology

maturity. Huawei has actively contributed in 3GGP standardization for Radio Resource

Control (RRC) Protocol specification, Base Station (BS) radio transmission and reception,

User Equipment (UE) radio transmission and reception, Medium Access Control (MAC)

protocol specification, channels assignment and mapping, scheduling enhancement and so

on.

In addition to the standardization, Huawei has great contribution for the development of

network elements for the support and deployment of DC-HSDPA technology. The first

edition of Huawei dual cell technology is considered in RAN12 series release.

5.1 Software upgraded Network Elements

The network elements developed by Huawei are hardware ready for the DC-HSDPA

operations and only software up-gradation required. The 4th generation NodeBs and

6810/6900 series RNC types are capable to support DC-HSDPA functionality through

software up-gradation. The joint scheduling, channel mapping and radio resource

management are handled only by the software change in the legacy elements.

Figure 5-1 – Huawei NodeB up-gradation for DC-HSDPA



5.2 Multi Carrier Transceivers

Huawei was the first vendor to provide multi carrier transceivers to the industry. Most of the

deployed UMTS networks by Huawei are configured with multi carrier transceivers, so it is

easy for those operators to upgrade their network for DC-HSDPA and future MC-HSDPA.

Figure 5-2 – Huawei Multi Carrier Benefits for DC-HSDPA Operations

5.3 Advance RRM and Schedulling Methods

Huawei use advance radio resource management and scheduling methods to improve the

performance and capability of DC-HSDPA. In the anchor cell-selection procedure, Huawei

has enabled advance algorithm based on load, service and capacity. The radio resource

admission check based on the power level is estimated for dual carrier users. The DC users

are assigned radio resources based on satisfying following power conditions:

Max Available HSDPA Power Admission of current carrier

Max Transmit Power Admission of current carrier

Max Available HSDPA Power Admission of DC Group

Max Transmit Power Admission of DC Group

For the scheduling process, the criteria for the scheduling assignment are dependent on the

following two factors:

The power utilization of Carriers

SC HSDPA user number of Carriers

The user is assigned one of the scheduler of two cells in such a way that it would not impact

the performance and capacity of entire cell and other users. Following main advantages are

realized from the above algorithm settings:

Enhance the QoE, Reduce waiting time for the Delay-Sensitive Services and Guarantee

the BE users’ throughput



Ensures the full use of resources for DC-Group

Realization of user-differentiation among DC and SC users

Figure 5-3 shows the scheduling priority and selection procedure for a DC-HSDPA user.

Figure 5-3 – Details of DC-HSDPA users scheduling Process



6 Conclusion

DC-HSDPA improves the user’s experience by adopting multi carrier technology. The user’s peak throughput similar to that of MIMO technology is achieved by the DC-HSDPA. The impact of signal channel quality on DC-HSDPA user’s throughput is less than that of MIMO and users at the far end of the cell receive higher data throughputs as compared to all other features of HSPA+.

DC-HSDPA users enjoy high data transmission rate in all the cell coverage area even in the cell edges. The deployment and configuration for DC-HSDPA is easy and low cost and have no negative impacts on the legacy HSDPA users and terminals.

The performance of DC-HSDPA is best for burst data services like http, gaming and low download files. The joint scheduling procedures in the NodeB insure the transmission of single user’s data through two cells and hence increase the transmission data rate.

DC-HSDPA is one of the key features of Huawei RAN 12 series based on 3GPP R8 standard. The entire network elements developed by Huawei fully supports DC-HSDPA technology with only software up-gradation. The multi carrier technology, advance radio resource management and improved scheduling techniques in Huawei network elements insure the quality of DC-HSDPA solution.



7 Acronyms and Abbreviations

Table 7-1 Acronyms and Abbreviations

Acronym and Abbreviation Expansion

3G The Third Generation

AMR Adaptive Multi-Rate

ARQ Automatic Repeat Request

AQM Active Queue Management

BBU Baseband Unit

BITS Building Integrated Timing Supply System

BTS Base Station

CCCH Common Control Channel

CPC Continuous Packet Connectivity

CPICH Common Pilot Channel

CQI Channel Quality Indicator

DL Downlink

DPCCH Dedicated Physical Control Channel

DPDCH Dedicated Physical Data Channel

DRX Discontinuous Reception

DTCH Dedicated Traffic Channel

DTX Discontinuous Transmission

DTxAA Double Transmit Antenna Array

EDCH Enhanced Dedicated Channel

FACH Forward Access Channel

HSDPA High Speed Downlink Packet Access



Acronym and Abbreviation Expansion

HSUPA High Speed Uplink Packet Access

HARQ Hybrid Automatic Repeat Request

HS-PDSCH High Speed Physical Downlink Shared Channel

HS-SCCH High Speed Shared Control Channel

MIMO Multi-Input Multi-Output

MAC Medium Access Control

PA Power Amplifier

PARC Platform Advanced Radio Control

PDU Protocol Data Unit

QAM Quadrature Amplitude Modulation

RAN Radio Access Network

RET Remote Electrical Antenna

RNC Radio Network Controller

RLC Radio Link Control

RRM Radio Resource Management

SAE System Architecture Evolution

TPC Transmit Power Control

TrCH Transport Channel

UL Uplink

VoCS Voice over Circuit Switch

VoIP Voice over IP

WCDMA Wideband Code Division Multiple Access

Huawei Dual Cell HSDPA Technology White Paper V1[1].0(20100128)

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