K022 - HSDPA Technology and Applied Planning

8/2/2019 K022 - HSDPA Technology and Applied Planning

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AIRCOM International 1 (110)

K022 - HSDPA

Technology and Applied Planning


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Document Control


Document Control

Change History

Version Date Author Description

1 30/06/2006 JL Martinez Creation of document

Reviewers

Name Description

Related Documents

Reference Document Number Title


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Contents

Document Control................................................................................................7

Change History ................................................................................................... 7Reviewers ................................................................................................... 7Related Documents................................................................................................8

Contents ................................................................................................... 9

Scope and Course Objectives............................................................................. 9Course Objectives..................................................................................................9Sessions ................................................................................................... 9Course Timetable...................................................................................................9

1 Introduction............................................................................... 9

1.1 Objectives of this session ...........................................................91.2 HSDPA Planning and Deployment - Intro.................................... 91.3 Session Summary Checklist ................................................9

2 HSDPA Background ................................................................. 92.1 Objectives of this session ...........................................................92.2 WCDMA Evolution...................................................................... 92.2.1 WCDMA Release 99 Review ..................................................... 92.3 Purpose of HSDPA.....................................................................92.3.1 Release 99 Principles ................................................................92.3.2 RRC Modes and States ..............................................................92.3.3 Adaptive Modulation and Coding ................................................92.3.4 Multicode Operation....................................................................9

2.3.5 Scheduling Concepts.................................................................. 92.3.6 HSDPA Scheduling and Retransmission.................. ................... 92.4 Session Summary Checklist ................................................9

3 HSDPA Concepts......................................................................93.1 Objectives of this session ...........................................................93.2 UMTS Network Architecture with HSDPA ................................... 93.3 HSDPA Channels .......................................................................93.3.1 HS-DPCCH................................................................................. 93.3.2 HS-SCCH ................................................................................... 93.3.3 HS-PDSCH.................................................................................93.4 HSDPA Rates.............................................................................93.4.1 Muti-code transmission...............................................................93.4.2 Hybrid Automatic Repeat Request HARQ................................ 93.5 HSDPA Physical Layer Performance..........................................93.6 Performance Metrics...................................................................93.7 Session Summary Checklist ................................................9


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Contents


4 HSDPA Network Planning........................................................ 94.1 Objectives of this session ........................................................... 94.2 HSDPA Link Budget ................................................................... 94.2.1 Power Allocation......................................................................... 94.2.2 Signal To Noise Ratio and Data Rate ......................................... 9

4.2.3 Margins....................................................................................... 94.2.4 Scheduling Gain ......................................................................... 94.2.5 Peak Throughput ........................................................................ 94.2.6 Considering HS-SCCH............................................................... 94.3 Network Planning Example.........................................................94.3.1 Deployment options.................................................................... 94.3.2 Mean Cell Throughput ................................................................ 94.3.3 Coverage Statistic....................................................................... 94.3.4 DCH vs HSDPA.......................................................................... 94.4 HSDPA Dimensioning................................................................. 94.4.1 Traffic Dimensioning................................................................... 94.4.2 Available PS Capacity ................................................................ 94.4.3 Multiservice Dimensioning .......................................................... 9

4.4.4 HSDPA RF Parameters ..............................................................94.5 Session Summary Checklist ................................................ 9


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Scope and Course Objectives

This document provides notes and supporting material for the HSDPA Technology and Applied

Planning Course. It is assumed that the assistant has knowledge in concepts of antennas, mobilescommunications and UMTS technology.

AIRCOM International offers most of these courses. Details could be review in our web page.

Course Objectives

The HSDPA Technology and Applied Planning Course is oriented for those engineers who design

UMTS and HSDPA networks, the contents will help to understand better this technology and to takeadvantage of its characteristics. It is advisable that course delegates have a very good knowledge of

antennas, radio propagation, mobile communications concepts and UMTS standards.

At the end of the course, delegates should gain knowledge to enable them to have a solid grasp of the

HSDPA background, concepts and radio planning. Delegates will also be able to complete the

following objectives:

Understand the concept of HSDPA

Understand the basics of standards related to HSDPA

Study evolution of HSDPA

Radio Planning in HSDPA

Apply dimensioning to HSDPA

Understand HSDPA RF parameters


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Scope and Course Objectives


Sessions

This course is divided into the following sessions:

1. Introduction

2. HSDPA Background

3. HSDPA Concepts

4. HSDPA Network Planning


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Course Timetable

Day 1 Day 2

Period Plan Period Plan

0930-1000 Session 1 : Introduction 0915-1000 Session 4 : HSDPA Network

Planning

1000-1045 Session 2 : HSDPA Background 1000-1045 Session 4 : HSDPA NetworkPlanning

1045-1100 Break 1045-1100 Break

1100-1145 Session 2 : HSDPA Background 1100-1145 Session 4 : HSDPA Network

Planning

1145-1230 Session 2 : HSDPA Background 1145-1230 Session 4 : HSDPA NetworkPlanning

1230-1330 Lunch 1230-1330 Lunch

1330-1415 Session 3 : HSDPA Concepts 1330-1415 Session 4 : HSDPA NetworkPlanning

1415-1500 Session 3 : HSDPA Concepts 1415-1500 Session 4 : HSDPA Network

Planning

1500-1515 Break 1500-1515 Break

1515-1600 Session 3 : HSDPA Concepts 1515-1600 Session 4 : HSDPA Network

Planning

1600-1630 Session 3 : HSDPA Concepts 1600-1630 Course Evaluation & Feedback


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Introduction


1 Introduction

1.1 Objectives of this session

During this session you will learn about:

HSDPA Planning and Deployment - Intro

1.2 HSDPA Planning and Deployment - Intro

As applied in others mobile communications technologies, Deployment and Planning are based on

previous performance and financial situation for expansion. For HSDPA is very importantperformance in UMTS network. KPI and statistics are clear enough to know exactly where and inwhich sites to add this capability.


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In previous figure is described deployment process as follows:

Auditing existing R99 network (UMTS).- Audit of hardware configuration, where HSDPAis possible and easy implementation.

Historical comparison of performance in existing R99 network.- Drive test analysis forevaluate HSDPA performance. Performance and usage:

o Average power used for existing traffic at BTS?o Separate or common carrier for HSDPA?o Bs processing card, RNC usage, and links performance (Iub)o More elements have to be added?o SHO information could be used for HSDPA mobility

Selection of areas or sites where HSDPA will be installed and deployment strategy.-Analysis and selection of upgrade and design method. Selection of sites and calendar for

deployment HSDPA in each one.

Configuration and Capacity planning.- Link configuration between RNC and BTS (Iub)based on capacity calculation (throughput needed). For each BTS, single or multicarrier

configuration, hardware necessary for HSDPA traffic. For RNC, cell administration capability

and installation of hardware for HSDPA.

Definition of DataFill for selected sites with HSDPA capability.- Datafill is selectedaccording to capacity and quality of service selected for HSDPA. Datafill should be updated

as traffic evolves.

Configuration test and performance.- Drive test with hardware and software have to beapplied in areas where HSDPA was deployed, using this method you realize if your

configuration is appropriate and having a good performance. If not acceptable you can back to

previous stage.


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Introduction


1.3 Session Summary Checklist

This checklist has been provided as a self-assessment of the objectives stated at the beginning of the

session.

Please tick all objectives covered in this Session:

HSDPA Planning and Deployment - Intro

Additional Notes:


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2 HSDPA Background



WCDMA Evolution

Purpose of HSDPA

2.2 WCDMA Evolution

EUL

Release 6

HSDPA

Release 5

WCDMA

Release 99

GPRSGSM

EDGE

WCDMA EvolutionWCDMA Evolution


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HSDPA Background


Above chart shows the evolution of WCDMA from GSM to deployed Release 99. HDSPA is includedin Release 5 of the specifications. Following Release 5, whose enhancements provides benefits for the

Downlink; Release introduces the Enhanced Uplink (EUL) that will provide faster services for Uplink.

Rates offered for WCDMA evolution technologiesRates offered for WCDMA evolution technologies

Uplink OnlyUplink OnlyEUL

14.4 Mbps10.0 MbpsHSDPA

2.0 Mbps384 kbpsWCDMA Release 99

473 kbps120 kbpsEDGE

171 kbps40 kbpsGPRS

9.6 kbps (CS)9.6 kbps (CS)GSM

Downlink Peak Data Rate

(Typical Maximun)

Downlink Peak Data Rate

(Typical Deployment)

Technology

Data rates for different technologies are presented, GSM is totally CS. Following technologies offers

increase in rate, these values are theoricals, however depends on radio propagation conditions, UEconfigurations and performance of Core Network.


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2.2.1 WCDMA Release 99 Review

WCDMA R99 includes three different channels for downlink packet data transmission:

WCDMA RWCDMA R99 channels for downlink packet data99 channels for downlink packet datatransmissiontransmission

Dedicated Channel (DCH),Downlink-Shared Channel (DSCH)

Forward Access Channel (FACH)

The FACH is a common channel offering low latency. However, it is not efficient since it

does not support fast closed loop power control. It is therefore limited to carrying only small

amounts of data traffic. The DCH is the primary data channel and can be used for any traffic

class. In the downlink, the DCH is allocated a certain orthogonal variable spreading factor

(OVSF: 4-512) according to the connection peak data rate, while the block error rate (BLER)

is controlled by inner and outer loop power control. The DCH code and power allocation are

therefore inefficient for bursty and low duty cycle data applications since channel re-

allocation can be very slow (in the range of 500 ms). The DSCH provides the possibility to

time-multiplex different users, improving the channel re-allocation time.


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HSDPA Background


HSDPA ConceptHSDPA Concept

Extension of the DSCH

Adaptive Modulation and Coding (AMC)

Short frames

Multi-code operation

Fast L1 Hybrid-ARQ (HARQ)

Node B scheduling

The HSDPA concept can be seen as an extension of the DSCH with the introduction of newfeatures such as Adaptive Modulation and Coding (AMC), short frames, multi-code

operation, fast L1 Hybrid-ARQ (HARQ) and Node B scheduling. In fact, these features

replace the two basic WCDMA features, namely Variable Spreading Factor (VSF) and fast

power control.


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2.3 Purpose of HSDPA

HSDPA introduces a number of new technical capabilities to the radio access network, which

when combined offer a significant improvement for both end users and operators.

Technical capabilities for HSDPA (complete)Technical capabilities for HSDPA (complete)

A new common High Speed Downlink Shared Channel(HS-DSCH) which can be simultaneously shared bymultiple users,

Shorter Transmission Time Interval (TTI) of 2ms, whichenables higher speed transmission in the physical layer,

Fast scheduling,

Adaptive Modulation and Coding (AMC),

Fast retransmission based on fast Hybrid AutomaticResponse reQuest (HARQ) techniques.

The HS-DSCH is shared channel with a number of Spreading Factor 16 (SF-16) CDMA

codes. Within each 2 ms TTI, a constant spreading factor of 16 is used with a maximum of 15parallel channels in the HS-DSCH. These channels may all be assigned to one user during the

TTI, or may be split amongst several HSDPA users. There is no Power Control with HSDPA

and the HS-DSCH is transmitted at a constant power while the modulation, the coding and the

number of codes are changed to adapt to the variations of radio conditions.


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HSDPA Background


Transmission Time Interval (TTI)Transmission Time Interval (TTI)

TTI = 8 ms

TTI = 2 ms

UMTS

HSDPA

The shorter 2ms Transmission Time Interval TTI (compared to TTI of between 10ms and80ms in UMTS R99) means that the systems is more reactive to changing user or radio

conditions and can quickly allocate capacity to users.


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Fast SchedulingFast Scheduling

Fast data traffic scheduling means that variations arising from changing radio conditions can

be accommodated and that the BTS is able to allocate as much of the particular cells capacity

to a particular user for a short period of time. This means that a user is able to receive as much

data as radio conditions will allow. This capability is often compared to the mechanisms used

in Wireless LAN (WLAN) systems.


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HSDPA Background


AMC (Adaptive Modulation and Coding)AMC (Adaptive Modulation and Coding)

Two possible modulation QSPK and 16 QAM Fast link adaptation

Coding Formats

QPSK16QAM

Adaptive Modulation Coding (AMC) with fast link adaptation means that the modulation and

coding formats can be changed in accordance with variations in the channel conditions,

leading to a higher data rate for users with favorable radio conditions. Whereas UMTS

Release 99 used only Quadrature Phase Shift Keying (QPSK) modulation, HSDPA provides

the ability to use 16-QAM when the link is sufficiently robust, which can lead to a significant

increase in data rate.


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HARQHARQ

Hybrid Automatic Repeat reQuest Implicit link adaptation technique Schemes for implementing HARQ

Incremental redundancy (IR)

-Additional redundancy is transmitted in retransmission

-Combining and coding gain

N channel stop-and-wait HARQ

AMC provides the coarse data rate selection, while H-ARQ provides fine data rate adjustment based onchannel conditions

Fast H-ARQ enables erroneous packets to be resent within a 10ms window, ensuring that the

TCP throughput remains high. In addition, in HSDPA the mechanisms for ARQ are moved to

the BTS (from the RNC in R99). By using these approaches, all users, whether near or far

from the base station, are able to receive the optimum data rate.


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HSDPA Background


2.3.1 Release 99 Principles

ReleaseRelease 99 Channels for Data Transmissions99 Channels for Data Transmissions

Dedicated Channel (DCH)

or the Forward Access Channel (FACH)

The Downlink Shared Channel (DSCH) is alsodefined, but has not been widely adopted or

implemented.

The Release 99 specification defines three difference techniques to enable Downlink packet

data. Most commonly, data transmission is supported using either the Dedicated Channel

(DCH) or the Forward Access Channel (FACH). The Downlink Shared Channel (DSCH) is

also defined, but has not been widely adopted or implemented.

The DCH is considered the primary means of supporting data. Each individual user isassigned a unique Orthogonal Variable Spreading Factor (OVSF) code dependent on the

required data rate. Fast closed loop power control is employed to ensure that a target Signal-to-Interference Ratio (SIR) is maintained in order to control the BLER. Macro diversity is

supported with the DCH in terms of soft handover.


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Data transfer can also be supported on the FACH. This common channel employs a fixed

OVSF code. As it needs to be received by all UEs, higher data rates are generally not

supported. Macro diversity is also not supported and the channel operates with a fixed (orslow changing) power allocation.

Channel Coding for an DSCHChannel Coding for an DSCH

The DSCH is a common channel that is always associated with a Dedicated Channel (DCH)

to enable closed loop power control. A common, variable spreading factor is shared among

many users with assignment controlled by Physical Layer signaling. Multi-code operation is

also possible enabling higher data rates.Although, DSCH has been implemented in

commercial TDD networks not in Release 99 FDD systems.


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HSDPA Background


2.3.2 RRC Modes and States

UTRAN Connected ModeUTRAN Connected Mode

URA_PCH

URA_PCH

URA_PCH

URA_PCH

Idle Mode

(Camping on a UTRAN cell)

ReleaseRRCConnection

EstablishRRCConnection

ReleaseRRCConnection

EstablishRRCConnection

Channels: PCH, NoUplink

Mobility: URAUpdate

Calls: PS (No datatransfer)

DRX Mode

Channels: DownlinkDCH, UplinkDCH

Mobility: Hand Over

Calls: PS , CS

Channels: PCH, NoUplink

Mobility: Cell Update

Calls: PS (No datatransfer)

DRX Mode

Channels: FACH, RACH

Mobility: Cell Update

Calls: PS

Dedicated logical channels,but commontransport andphysical channels.

No DRX Mode

Channels: PCH, No Uplink

Mobility: Location/Routing, Area Update

Calls: None, PS call might be context preserved state

DXR Mode

RRC Modes

Idle Mode

UTRAN Connected Mode

UTRAN Connected Mode

CELL_DCH

CELL_FACH

CELL_PCH

URA_PCH


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RRC Connection: Between UE and RNC

Registration (Attach, Location/Routing Area Update, URA Update): Between UE andCore Network (SGSN or MSC)

RRC statesRRC states

Cell_DCH

Cell_FACH

Cell_PCH URA_PCH

Assignment of the different channels to a user and control of the radio resources in general are

performed by the Radio Resource Control protocol (RRC). In UTRAN Connected Mode thereare four RRC states the UE can switch between: Cell_DCH, Cell_FACH, Cell_PCH and

URA_PCH.


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HSDPA Background


CELL DCHCELL DCH

UL Channel allocation

DL Channel allocation

In the Cell_DCH state the UE has been allocated a dedicated physical channel in uplink and

downlink. In the three other states the UE is not allocated a dedicated channel.


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Cell FACHCell FACH

UE monitors forFACH channel inDL

Cell reselection

In the Cell_FACH the UE monitors a RACH channel in the downlink and is allocated a

FACH channel in the uplink direction. Also in this state the UE performs cell reselections; by

sending cell update messages the position of the UE is known on cell level by the RNC.


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HSDPA Background


Cell_PCHCell_PCH and URA_PCHand URA_PCH

No UL activity These channels are used basically for paging

In both the Cell_PCH and the URA_PCH state the UE selects a paging channel (PCH), and

uses discontinuous reception (DRX) for monitoring the selected PCH via an associated PICH.

No uplink activity is possible in this state. The only difference between both states is that in

the Cell_PCH state the location is known on cell level according to the last cell update made

while in the URA_PCH state the location is known only to UTRAN Registration Area (URA)

level according to the last URA update made in the Cell_FACH state.


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2.3.3 Adaptive Modulation and Coding

Adaptive Modulation and CodeAdaptive Modulation and Code

QPSK

Modulator

16QAM

Modulator

Spreading

Spreading

2 bits

4 bits

3.84 Mcps

3.84 Mcps

Adaptive Modulation Coding (AMC) with fast link adaptation means that the modulation and

coding formats can be changed in accordance with variations in the channel conditions,

leading to a higher data rate for users with favorable radio conditions. Whereas UMTS

Release 99 used only Quadrature Phase Shift Keying (QPSK) modulation, HSDPA provides

the ability to use 16-QAM when the link is sufficiently robust, which can lead to a significant

increase in data rate.


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HSDPA Background


AMC and CQIAMC and CQI

1

4

3

2

16QAM

QPSK

CQIReport

QPSKPoor4

QPSKMedium3

16QAMVery Good2

16QAMGood1

Modulation

SignalQuality

UE

AMC is a fundamental feature of HSDPA. It consists of continuously optimizing the code

rate, the modulation scheme, the number of codes employed and the transmit power per code

based on the channel quality reported (CQI feedback) by the UE. The HS-DSCH encoding

scheme is based on the R99 rate (1/3 Turbo encoder) but adds rate matching with puncturing

and repetition to improve the granularity of the effective code rate (1/4 to 3/4).


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Data Rates and ModulationsData Rates and Modulations

1

4

3

2

16QAM

QPSK

QPSK119 Kbps4

QPSK712 Kbps3

16QAM14.4 Mbps2

16QAM10.8 Mbps1

AMCRateUE

In order to achieve very high data rates. Different combinations of modulation and the

channel coding-rate (based on the Transport Format and resource combinations or TFRC) can

be used to provide different peak data rates (e.g. 119 kbps/code with QPSK and 1/4 code rate,

712 kbps/code with 16QAM and 3/4 code rate).

Essentially, when targeting a given level of reliability, users experiencing more favorable

channel conditions (e.g. closer to the Node B) will be allocated higher data rates. The

HSDPA-capable UE can support the use of five, 10 and 15 multi-codes. A single user can

receive up to 15 multi-codes resulting in a potential peak data rate of 10.8 Mbps. However,the maximum specified peak data rate with HSDPA is 14.4 Mbps (or 960 kbps/code) when

16QAM modulation is used with no coding (effective code rate of one) and 15 multicodes.

Achieving this rate in a real system remains very unlikely as it would require an unloadedsystem serving a single user extremely close to the Node B.


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HSDPA Background


Power utilization for HSPower utilization for HS--DSCHDSCH

Release 99

HSDPA

HS-DSCH

Another benefit of AMC is better utilization of the Node B power. If no power constraints are

specified, the leftover power from the dedicated channels (R99) can be allocated to HS-

DSCH resulting in near-maximum power utilization.


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2.3.4 Multicode Operation

MulticodeMulticode OperationOperation

First, HSDPA uses high speed data channels called High Speed - Downlink Shared Channels

(HSDSCH). Up to 15 of these can operate in the 5 MHz WCDMA radio channel. Each uses a fixedspreading factor of 16.

User transmissions are assigned to one or more of these channels for a short transmission time intervalof 2 msec, significantly less than the interval of 10 to 20 msec used in WCDMA. The network can

then readjust how users are assigned to different HS-DSCH every 2 msec. The result is that resources

are assigned in both time (the TTI interval) and code domains (the HS-DSCH channels). Figure,

illustrates different users obtaining different radio resources.

Time


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HSDPA Background


2.3.5 Scheduling Concepts

Scheduling ConceptsScheduling Concepts

Is related to performance of the system

Fir each TTI determines which terminal or terminal receiveHS-DSCH

Works in conjunction with AMC

Located in Node B

For data rate allocation some algorithms are used like: Round Robin (RR)

Maximum Carrier to Interference (C/I)

Proportional Fair (PF)

The scheduler is a key element of HSDPA that determines the overall behavior of the system and, to acertain extent, its performance. For each TTI, it determines which terminal (or terminals) the HS-

DSCH should be transmitted to and, in conjunction with the AMC, at which data rate. One important

change from R99 channels is that the scheduler is located at the Node B as opposed to the RNC. Inconjunction with the short TTI (2 ms) and the CQI feedback, this enables the scheduler to quickly

track the UE channel condition and adapt the data rate allocation accordingly. Several algorithms can

be used for the scheduler. Some of them are: Round Robin (RR), Maximum Carrier to Interference(C/I) and Proportional Fair (PF).


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RR schedulerRR scheduler

Schedules users according to a first-in first-out approach

Provides a high degree of fairness between users

Some users can be served even when they are experiencing destructive fading

Round Robin

RR schedules users according to a first-in first-out approach. It provides a high degree of fairness

between the users, but at the expense of the overall system throughput (and therefore spectral

efficiency), since some users can be served even when they are experiencing destructive fading (weak

signal).


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HSDPA Background


Maximum C/I schemeMaximum C/I scheme

Schedules users with the highest C/I during the current TTI

Served users are the ones with the best channel

This scheme makes no effort to maintain any kind of fairness among users

TTI TTI TTI TTI

Maximum C/I

The maximum C/I scheme schedules users with the highest C/I during the current TTI. This naturally

leads to the highest system throughput since the served users are the ones with the best channel.However, this scheme makes no effort to maintain any kind of fairness among users. In fact, users at

the cell edge will be largely penalized by experiencing excessive service delays and significant outage.


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PF SchemePF Scheme

Offers a good trade-off between RR and maximum C/I

Schedules users according to the ratio between their instantaneous achievabledata rate and their average served data rate

PF Scheme

The PF scheme offers a good trade-off between RR and maximum C/I. The PF schedules usersaccording to the ratio between their instantaneous achievable data rate and their average served data

rate. This results in all users having equal probability of being served even though they may

experience very different average channel quality. This scheme provides a good balance between the

system throughput and fairness. It is important to mention that the implementation of QoS (i.e.different subscription classes) creates new constraints on the scheduler. Other parameters such as user

priority level may override the above scheduling algorithms. The fairness between the users will then

be dominated by the QoS requirements.


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HSDPA Background


Node B ScheduleNode B Schedule

t1

t2

t3

t4t5

t5

t4

t3

t2

t1

Schedule

To allow the system to benefit from the short-term variations, the scheduling decisions are done in the

Node B. The idea in HSDPA is to enable a scheduling such that, if desired, most of the cell capacitymay be allocated to one user for a very short time, when conditions are favorable. In the optimumscenario, the scheduling is able to track the fast fading of the users.


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2.3.6 HSDPA Scheduling and Retransmission

Scheduling and Retrasmission are different; in next tab these differences are tabulated:

HSDPA Scheduling and RetransmissionHSDPA Scheduling and Retransmission

Soft combining at the UE

Based on UE feedback (ACK/NACK)Based on channel quality feedback fromUE

HARQ(link level retransmissions)No interaction with RNC

Done at Node BDone at Node B

RetransmissionsScheduling

All transport channels for Release 99 terminate at RNC. Hence, retransmission procedure for packetdata is located in serving RNC, which also controls connection for particular user to core network.With introduction of HSDPA additional procedures and algorithms we designed and implemented in

MAC layer installed at Node B. In this way, retransmissions could be managed by Node B, leading tofaster retransmissions and thus shorter delay with packet data operation when retransmissions are

needed.


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HSDPA Background


ReleaseRelease 9999 retranmissionretranmission

RNC NodeB

UE

Packet

Retransmission

HSDPA retransmissionHSDPA retransmission

RNC Node B

UE

Packet

Retransmission

Figure above is representing differences between Release 99 and HSDPA, as we mentioned before

retransmission is manage by RNC in first case, however in case that many RNC are serving samemobile and no relocation procedure is implemented, terminating point could be several RNC further

into network.


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session.


WCDMA Evolution

HSDPA Purpose

Additional Notes:


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HSDPA Concepts


3 HSDPA Concepts



UMTS Network Architecture with HSDPA

HSDPA Channels

HSDPA Rates

HSDPA Physical Layer Performance

Performance Metrics

3.2 UMTS Network Architecture with HSDPA

UMTS Network Architecture with HSDPAUMTS Network Architecture with HSDPA

User Equipment

USIM

MobileEquipment

UTRAN CORE Network

Node B

Node B

Node B

Node B

Node B

Node B

Node B

Node B

RNC

RNC

SGSN

HLR/AuC

MSC/VLR

HW & SWUpgrade

SW Upgrade

UE

Uu

Iub

Iub

Iups

IucsGMSC

GGSN


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Adding HSDPA to an existing UMTS network requires no new network entities, but hardware and/or

software changes may be required foe each entity. The changes are concentrated in the UE, Node B

and RNC. Interface changes are concentrated on the Uu interface between UE and Node B and on the

Iub interface between Node B and RNC.

Interface changesInterface changes

UE and Node.- Require hardware and software changes tosupport the new channels and functionality of HSDPA.

RNC.- Requires software changes to support the new

signalling messages used to configure and manageHSDPA channels.

Uu Interface.- Requires new signalling messagesexchanged over existing signalling channels and newtransport and physical channels to support high-speedoperation.

Iub Interface.- Requires a new frame protocol for sendinghigh speed user data from RNC to Node B.

No functional changes to the Iups are required, although there may be bandwidth issues to support

higher data rates to multiple users.


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HSDPA Concepts


3.3 HSDPA Channels

Channels in HSDPA are divided as follows:

HSDPA ChannelsHSDPA Channels

TRANSPORTChannel High Speed Downlink Shared Channel (HS-DSCH, Downlink

Transport Channel)

PHYSICAL Channel High Speed Shared Control Channel (HS-SCCH, Downlink

Control Channel)

High Speed Physical Downlink Shared Channel (HS-PDSCH,Downlink Data Channel)

High Speed Dedicated Physical Control Channel (HS-DPCCH, Uplink Control Channel)


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3.3.1 HS-DPCCH

HSHS--DPCCHDPCCH

The HS-DPCCH (SF=256) carries ACK/NACK signaling indicating whether the corresponding

downlink transmission was successfully decoded, as well as a Channel Quality Indicator (CQI) to beused for the purpose of link adaptation. The CQI is based on the Common Pilot Channel (CPICH) and

is used to estimate the transport block size, modulation type and number of channelization codes that

can be supported at a given reliability level in case of a downlink transmission. The feedback cycle ofthe CQI can be set as a network parameter in predefined steps of 2 ms. When longer feedback cycles

are used, the PDCH power-control commands can be used to update the channel quality estimate.


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HSDPA Concepts


3.3.2 HS-SCCH

HSHS--SCCHSCCH

The HS-SCCH is a fixed rate (60 kbps, SF=128) channel used for carrying downlink signaling

between the Node B and the UE before the beginning of each scheduled TTI. This includes the UE

identity (via a UE-specific CRC), HARQ related information and the parameters of the HS-DSCHtransport format selected by the link adaptation mechanism. Multiple HS-SCCHs can be configured in

each sector to support parallel HS-DSCH transmissions. A UE can be allocated a set of up to four HS-

SCCHs, which it needs to monitor continuously. In any given TTI, a maximum of one of these HS-

SCCHs may be addressed to a particular UE. When a UE detects a message addressed to it on aspecific HS-SCCH, it may restrict its monitoring of HS-SCCHs to only that HS-SCCH in the next

TTI3, therefore reducing the complexity of the UE.


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3.3.3 HS-PDSCH

HSHS--DPCCHDPCCH

High-Speed Downlink Shared Channel (HS-PDSCH) is a downlink physical channel shared by several

UEs. It supports Quadrature Phase Shift Keying (QPSK) and 16-Quadrature Amplitude Modulation

(16-QAM) and multi-code transmission. It is allocated to a user at 2 ms intervals.


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HSDPA Concepts


A UE is a member of one of 12 categories, as a function of its hardware capabilities. Each category

represents different values of the following parameters:

Channel Allocation (1)Channel Allocation (1)

Number of simultaneous HS-PDSCH codes (5,10 or 15)

Maximum transport block size Inter TTI interval minimum time between consecutive

assignments

Incremental redundancy buffer size- used to soft- combinesymbols from retransmissions


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Channel Allocation (2)Channel Allocation (2)

In HSDPA, the UE reports the channel conditions to the BTS via the uplink channel CQI field in theHS-DPCCH. The CQI value can be 0 to 30, with a value of 0 indicating out-of-range.


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HSDPA Concepts


Each CQI value corresponds to a certain transport block size, number of HS-PDSCHs, modulationformat, reference power adjustment, virtual IR buffer size, and RV parameter for a certain UE

category.

CQI ValuesCQI Values

09600-816QAM5716830

09600016QAM5356516

096000QPSK5331915

096000QPSK11371

Out of

range

Out of

range

Out of

range

Out of

range

Out of

range

Out of

range

0

RVNIR

1Reference

power

dB

Modulatio

n

Number of

HS-

PDSCH

Transport

block size

CQI Value

1. NIR is the virtual incremental redundancy buffer size per HARQ process

The UE reports the maximum CQI value whose corresponding parameters would theoretically provide

an acceptable block error ratio (BLER) for the current link conditions.


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The reported CQI value is then used by the Node B in combination with other parameters to determinethe appropriate coding configuration for the next packet transmission to the UE. To fully define the

coding configuration for a certain transmission, the Node B must select the following parameters:

Node B parameters used with CQINode B parameters used with CQI

Transport block size (254 from which to choose)

Modulation typeQPSK or 16 QAM

Number of physical downlink codes (1 to 15) Rate-Matching parameters: virtual IR buffer size

and RV (or data puncturing scheme)

However, even though there are a limited number of CQI values, there are literally thousands of

configurations from which the Node B, can choose for a certain transmission.


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HSDPA Concepts


3.4 HSDPA Rates

Theorical maximum data rate is 14 Mbps. The following techniques are used to achieve this data rate:

HSDPA Data RatesHSDPA Data Rates

Multi-code transmission- Up to 15 HS-PDSCH channels may beassigned to a single UE during one 2 ms TTI.

Consecutive assignments- The HARQ procedure allows the Node B

to send back-to-back assignments at 2 ms intervals. Lower Coding Gain- The block size of 320 bits was chosen,

assuming a turbo code rate of 1/3. Higher data rates can be achievedby puncturing more bits for a higher effective code rate (and lowercoding gain).

16-QAM- This modulation scheme increases the data rate overQPSK by a factor of 2.

The largest transport block size is 27,952 bits, which corresponds to the highest data rate of 13.976Mb/s (27,952 bits/2 ms = 13.976 Mb/s). This data rate is obtained by using 16 QAM, an effective code

rate of 0.9714, and 15 HS-PDSCHs.


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3.4.1 Muti-code transmission

MutiMuti--code transmissioncode transmission

14 Mbps9.6 Mbps4.8 Mbps4/416QAM

10.7 Mbps7.2 Mbps3.6 Mbps3/416QAM

7.2 Mbps4.8 Mbps2.4 Mbps2/416QAM

5.4 Mbps3.6 Mbps1.8 Mbps3/4QPSK

3.6 Mbps2.4 Mbps1.2 Mbps2/4QPSK

1.8 Mbps1.2 Mbps600 Kbps1/4QPSK

Throughput

with 15 codes

Throughput with

10 codes

Throughput

with 5 codes

Coding RateModulation

HSDPA allows up to 15 code multi code. Each HS-PDSCH uses an OVSF of length 16. The Node Bsignals the number of codes to the UE in the HS-SCCH. The number of codes supported by UE is one

factor in determining the UEs HSDPA category. The allowed choices are 5, 10, or 15 codes. Table

shows different rates allowed based on number of codes and modulation scheme.


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HSDPA Concepts


3.4.2 Hybrid Automatic Repeat Request HARQ

Hybrid Automatic Repeat Request (Hybrid ARQ.) Hybrid refers to a process of combining repeated

data transmissions with prior transmissions to increase the likelihood of successful decoding.

Managing and responding to real time radio variations at the Node B as opposed to an internalnetwork node reduces delays and further improves overall data throughput.

HARQHARQ

Hybrid Automatic Repeat Request (Hybrid ARQ.)

Hybrid refers to a process of combining repeated datatransmissions

Managing and responding to real time radio variations

Reduces delays and further improves overall data throughput

HARQ is the selected retransmission mechanism for HSDPA

Stop and Wait protocol (SAW). HARQ allows the UE to rapidlyrequest retransmission of erroneous transport blocks

HARQ functionality is implemented at the MAC

Therefore the retransmission delay of HSDPA is much lower than forR99

HARQ is the selected retransmission mechanism for HSDPA with Stop and Wait protocol (SAW).HARQ allows the UE to rapidly request retransmission of erroneous transport blocks until they are

successfully received. HARQ functionality is implemented at the MAC-hs (Media Access Control

high speed) layer, which is terminated at the Node B, as opposed to the RLC (Radio Link Control),which is terminated at the RNC.

Therefore the retransmission delay of HSDPA is much lower than for R99. In normal circumstances,

a NACK may require less than 10 ms at the MAC layer, while it can take up to 100 ms at the RLC

layer when Iub signaling is involved. This significantly reduces the delay jittering for TCP/IP anddelay sensitive applications.


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HARQ SchemeHARQ Scheme

Turbo

Encoder

Bit

Separation

First ratematching

IR

Buffer

Second ratematching

Parity bits

Redundancyversion

setting

Physical channelsegmentation

Systematicbits

The HARQ functionality is implemented by means of a two-stage rate-matching functionality, with

the principle illustrated in above figure. The principle shown contains a buffer between the rate-

matching stages to allow tuning of the redundancy settings for different retransmissions between therate-matching stages.

The buffer shown should be considered only as virtual buffer as the obvious practical rate-matchingimplementation would consist of a single rate-matching block without buffering any blocks after the

first rate-matching stage. The HARQ functionality is basically operated in two different ways. It is

possible to send identical retransmissions, which is often referred to as chase or soft combining. Withdifferent parameters, the transmissions will not be identical and then the principle of incremental

redundancy is used.

Hybrid ARQ is a combination of ARQ and Forward Error Correction (FEC). The erroneous blocks are

kept and are used for a combined detection with the retransmissions. There are various types: Code

Combining, Incremental Redundancy (IR), Chase combining.


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HSDPA Concepts


3.5 HSDPA Physical Layer Performance

The performance of HSDPA depends on a number of factors that include the following:

HSDPA Physical Layer PerformanceHSDPA Physical Layer Performance

Channel conditions: Time dispersion, cell environment, terminal velocity as wellas experienced own cell interference to other cell interference ratio (Ior/Ioc).Compared to the DCHs, the average Ior/Ioc ratio at the cell edge is reduced for

HSDPA owing to lack of soft handover gain. Macrocell network measurementsindicate typical values down to 5 dB compared to approximately 2 to 0 dB forDCH.

Terminal performance: Basic detector performance (e.g. sensitivity andinterference suppression capability) and HSDPA capability level, includingsupported peak data rates and number of multi-codes.

Nature and accuracy of radio resource management(RRM): Power and coderesources allocated to the HSDPA channel and accuracy/philosophy of Signalto Interference power ratio (SIR) estimation and packet-scheduling algorithms

In more detail, following points shows some possible performance issues that have been addressed in

the 3GPP specifications:


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1. - CQI report performance

1.1. -- CQI report performanceCQI report performance

1

4

3

2

16QAM

QPSK

HS-PDSCH

HS-PDSCH

HS-PDSCH

HS-PDSCH

CQI Performance

Timing, report accuracy,

CQI power offset, emissions

Node B detection

CQI report enables Node B to schedule HS-PDSCH sub frame transmissions with coding andmodulation appropriate to the channel conditions. Some issues to consider: Timing, report accuracy,

CQI power offset, emissions and Node B detection.


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HSDPA Concepts


2. - HS-SCCH and HS-PDSCH performance

2.2. -- HSHS--SCCH and HSSCCH and HS--PDSCH performancePDSCH performance

1

4

3

2

HS-PDSCH

HS-PDSCH

HS-PDSCH

HS-PDSCH

HS-SCCH and HS-PDSCH Performance

UE decoding reliability,

Data consistency

Retransmissions

Possible performance factors relates to the HS-SCCH: timing, detection and Node B waveform. ForHS-PDSCH: UE decoding reliability, data consistency, retransmissions.


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3. - ACK/NAK performance

3.3. -- ACK/NAK performanceACK/NAK performance

1

4

3

2

ACK/NAK

ACK/NAK

ACK/NAK

ACK/NAK

ACK/NAK Performance

Timing,

ACK/NACK power offset,

emissions and

Node B detection.

Considering the generation of an ACK/NAK and its transmission to the Node B on the HS-DPCCH,

following factors require consideration: timing, ACK/NACK power offset, emissions and Node B

detection.


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HSDPA Concepts


4. - Demodulation and decoding issues

4.4. -- Demodulation and decoding issuesDemodulation and decoding issues

1

4

3

2

ACK/NAK

ACK/NAK

ACK/NAK

ACK/NAK

Demodulation and decoding issues

Detection and decoding of

HS-SCCH by UE

HS-PDSCH both QPSK

and 16-QAM

modulation and

demodulation performance

HS-SCCHDetection

HS-SCCHDetection

HS-SCCH

Detection

HS-SCCHDetection

CQI Report

Issues to consider: Detection and decoding of both the CQI report and ACK/NACK. Detection and

decoding of HS-SCCH by UE should be considered. HS-PDSCH both QPSK and 16-QAMmodulation and demodulation performance should be considered.


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5. - RF performance

5.5. -- RF performanceRF performance

High PAR

Power offsets CQIand ACK

Signal waveformquality for 16QAM

Node B time anpower mask

On Uplink, the addition of another spreading code to DPCCH and DPDCH introducesthe possibility of higher PAR (Peak to Average Ratios). This could result in theviolation of adjacent channel protection. Also different power offsets of CQI report,

ACK/NACK could violate existing time and power masks.

On Downlink, signal waveform quality of the Node B, needs consideration due to theintroduction of HS-SCCH and HS-PDSCH, especially for 16-QAM modulation. Thismodulation has greater vulnerability to both phase and amplitude errors. Node B time

and power mask maybe violated with introduction of HS-SCCH and HS-DPSCH.


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HSDPA Concepts


3.6 Performance Metrics

Next list are performance metrics defined in Release 5 of HSDPA:

Performance MetricsPerformance Metrics

HS-PDSCH/HS-DSCH UE decoding performance: limits for minimum throughput with various reference

channels

UE 16-QAM demodulation: limits for minimum throughput at maximum input power level

Accuracy of Node B waveform with 16-QAM

HS-SCCH UE detection performance: limits for miss alarm probability UE decoding performance: covered by limits on HS-DSCH throughput

HS-DPCCH UE CQI reporting accuracy: limits on packet error rates on HS-DSCH for specific

reported CQI values.

UE emissions: limits for power back-off due to higher PAR

UE signal quality: time and power masks

Node B detection performance: limits for maximum error rates of ACK to NACK/ACK toDTX and DTX to ACK error events.

Considering HS-PDSCH, minimum throughput limits are specified per UE category using various

reference channels in differing interference and power allocation scenarios. Further, a minimumthroughput limit is specified for 16-QAM modulation.

For HS-SCCH, both detection and decoding performance limits are specified. For detection, limits for

the probability of a miss-alarm are specified, while decoding performance is covered by throughputlimits specified for HS-DSCH.

The addition of an extra code for HS-DPCCH prompted the introduction of UE maximum powerback-offs due to increased PAR and specification of a time and power mask to specify timing andaccuracy of any power stepping.


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session.


UMTS Network Architecture with HSDPA

HSDPA Channels

HSDPA Rates

HSDPA Physical Layer Performance

Performance Metrics

Additional Notes:


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HSDPA Network Planning


4 HSDPA Network Planning



HSDPA Link Budget

Network Planning Example

HSDPA Dimensioning

4.2 HSDPA Link Budget

Since HSDPA is expected to be overlaid on a WCDMA (R99) network, the principle of HSDPA linkbudget is to estimate the maximum data rate achievable in the downlink at the cell edge, assuming that

the coverage is uplink limited.

LinkLink Budget (1)Budget (1)

SlowerFaster Peakdata

Distance


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Link Budget (2)Link Budget (2)

Ec/Io

Ioc/Ior

HSDPA uses constant transmission power with fast link adaptation where effective coding rate andmodulation are adjusted to account for changes in radio condition. This is fundamentally different

from fast power control with fixed coding and modulation employed in Release 99, where

transmission power is adjusted so that a target Signal to Noise Ratio is achieved. With HSDPA, this

result in a distribution of peak data rates throughput a cell coverage area relating to both distance fromantenna and propagation conditions associated with each user, this result in cell throughput

distribution.


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For analysis of link budget some key parameters for a particular service and path loss allowed, areused:


Maximum Ec/Io. Generally represented as a fraction of total PApower, this is maximum power that can be allocated to a TrafficChannel for a particular service.

Ioc/Ior. Ioc is effectively interference and is power density of all cellsthat UE is not in soft handover with. Ior is power density of Downlinkreceived signal and includes cells that UE is in soft handover with.

. A combining gain with number of cells that UE is in soft handoverwith.


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43.0 dBm43.0 dBm43.0 dBm43.0 dBmBTS Tx Power (dBm)

20.0 W20.0 W20.0 W20.0 WBTS Tx Power (W)

1 dB1 dB1 dB1 dBBody Loss

3.0 dB3.0 dB3.0 dB3.0 dBBTS Cable Losses

18 dBi18 dBi18 dBi18 dBiNode B Antenna Gain

BTS Parameter

60%60%60%60%Average SPER

0.0 dB0.0 dB0.0 dB0.0 dBScheduling Gain

50.00%50.00%50.00%50.00%Orthogonality Factor

5.0 dB5.0 dB5.0 dB5.0 dBHS-SCCH Margin

-19.4 dB-19.4 dB-19.4 dB-19.4 dBHS-SCCH Ec/Nt

1 dB1 dB1 dB1 dBInterference Factor Ioc/Ior @ Cell Edge

-2.2 dB-2.2 dB-2.2 dB-2.2 dBScheduling Margin

80%80%80%80%%Power Allocated to HSDPA

20%20%20%20%Overhead Channels (C-PICH, P-CCPCH, S-C)

HSDPA Related Parameters

117.5 dB117.5 dB117.5 dB117.5 dBPath Loss

64 kbps64 kbps64 kbps64 kbpsData Rate

PS 64PS 64PS 64PS 64Service

RA3 & RA120TU3 & TU30TU3 & TU30TU3 & TU30Channel Model

UL WCDMA Network Design

RuralSuburbanUrbanDense Urban


960 Kbps768 Kbps832 Kbps832 KbpsMax MAC Data Rate

2400 Kbps1920 Kbps2080 Kbps2080 KbpsMax PHY Data Rate

-2.9 dB-3.9 dB-3.8 dB-3.8 dBMax Ec/Nt

-1.3 dB-1.3 dB-1.3 dB-1.3 dBAvailable Ec/Ior

-12.8 dB-11.9 dB-11.9 dB-12.0 dBControl Channel Ec/Ior

-1.0 dB-1.0 dB-1.0 dB-1.0 dBTotal Traffic Ec/Ior

-173.8dBm/Hz-173.8dBm/Hz-173.8dBm/Hz-173.8dBm/HzThermal Noise Floor

0.0 dB0.0 dB0.0 dB0.0 dBUE Antenna Gain

8.0 dB8.0 dB8.0 dB8.0 dBUE Noise Figure

UE Parameters


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The link budget estimates the users channel quality (i.e. Ec/Nt) that is then mapped to the maximum

achievable physical layer (PHY) data rate (adjusted for RLC overhead). The MAC level data rate

accounts for HARQ retransmissions. Above table, indicates that for 80 percent power allocation to

HSDPA and two retransmissions per transport block (typical value), the possible peak data rate at the

cell edge for a single user can reach 2 Mbps at the physical layer and 800 kbps at the MAC layer. In anactual loaded system,

HSDPA user data rates can be at least three times higher than what one can get with the currently

deployed WCDMA networks. It is important to note, however, that the peak data rate calculation does

not reflect any time-multiplexing, scheduling strategy or UE code capabilities.


1

4

3

2

14.4 Mbps

10 Mbps

6 Mbps

2 Mbps

It simply estimates the maximum data rate that a user can get if all the Node B resources (power and

codes) are available. As mentioned before, the obtained data rates strongly depend on the percentageof power allocated to HSDPA, users and Eb/N0. Since HSDPA and R99 channels may operate on the

same frequency (at least in early deployment phases), the power sharing becomes an important issue

for WCDMA (UMTS) operators. A relation between voice capacity, data sector throughput and

offered data rates must be found.


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It is clear that the highest data rates will be obtained when HSDPA is deployed on a separatefrequency.

Another important concept in HSDPA downlink is Cell Geometry, that is ratio of power received from

target cell (Ior), including cells with which mobile is in soft handover, to interference from all othercells (Ioc).

Cell GeometryCell Geometry

One specific cell geometry will achieve a certain Eb/Nt in UE for a given fraction of total transmitpower (Ec/Ior) allocated to Traffic Channel.


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Cell Geometry (2)Cell Geometry (2)

Is necessary SIR at UE

Range is from -3 to 30 dB, depending on channel model

Depending of position in cell, we have -3 dB at cell edge and 20 dBnear tower

A fraction of transmit power per traffic channel (Ec/Ior) for 1%BLERR for voice and CS Data, and up to 5% BLER for PS data

Ior/Ioc depends on handover condition, typical cell geometry,

Ior/Ioc=-3 dB Sometimes expressed in a Link Budget as Ioc/Ior, which is inverse of

cell geometry (Cell Geometry (dB)= -Ioc/Ior dB)


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Another useful concept related to Link Budget is Eb/Nt that is defined as signal to total noise ratio perbit at UE antenna connector. Total noise density, Nt, is the sum of thermal noise density, Nth, plus

interference density, Ioc. Last variable, Ioc is interference density from other cells not in soft handover

with UE. Typically Ioc >> Nth.

Eb/NtEb/Nt

QoS profile,

Propagation conditions(multipath, interference,etc),

Diversity performance

Coding

Eb/Nt

As is counterpart Eb/No in UMTS system, Eb/Nt depends on: QoS profile, propagation conditions(multipath, interference, etc), diversity performance and coding.


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According to 3GPP dedicated channel Eb/Nt with soft handover (DCH Eb/Nt) is estimated usingfollowing formula:

Eb/NtEb/Nt (2)(2)

=

+

=L

i

OR

OC

i

or

c

t

b

aII

a

RateDatanInformatio

RateChip

I

EDPCH

N

EDCH

1 2

2

)1(*__

_

*

_

In this formula, predicted DCH Eb/Nt considers soft handover in the last term named interference

term. Where is combining gain and a2

considers weight of each multipath component.


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4.2.1 Power Allocation

Power Allocation (1)Power Allocation (1)

60% of maximum total Node B power and neighboring cellsallocate a certain percentage of this power to HSDPA

Power allocation in hotspot cell and neighboring cells is done at the network management level and

signaled to Node B. In this procedure, hotspot or serving cell gives 60% of maximum total Node B

power and neighboring cells allocate a certain percentage of this power to HSDPA proportionally tothe number if users.


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Power allocation is calculated by means of:


cellservingusers

iuser

HSDPAiN

NPP

=

,

,

Where:

Pi is the power allocated for HSDPA in cell i.PHDSPA is the power allocated to HSDPA in serving cellNuser,I is the number of users in cell i.

Nusers,serving-cell is number of users in serving-cell


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Two possible schemes are likely to be deployed:


Static- A fixed percentage of total available PA power is allocated forDownlink HSDPA channels, with remaining distributed amongrequired common channels and power controlled dedicatedchannels.

Dynamic- Power of Downlink HSDPA channels is allocateddynamically such that power is be assigned to required commonchannels and power controlled dedicated channels first, withremainder allocated to Downlink HSDPA channels.

Power allocated is signaled to UE and reflected in CQI report. Priority of HSDPA transmissionsrelative to other services is reflected in choice of power allocation scheme.

In HSDPA, achieved SIR relates to an achievable throughput based on modulation, coding and

transport block size.


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4.2.2 Signal To Noise Ratio and Data Rate

Signal To Noise Ratio and Data RateSignal To Noise Ratio and Data Rate

0

2

4

6

8

10

12

14

-12 -10 -8 -4 0 4 8 10

Ec/Nt (dB)

Data

Rate

(M

bps)

Signal to Interference Ratio (SIR), BLER (Block Error Rate) and Eb/No are related in HSDPA in

similar way that they are in WCDMA. We need for different services, different Eb/No requirementsand minimum values of SIR to maintain low BLER values.

UE estimates SIR (also known as C/I or Ec/Nt) and related propagation conditions. Following graph is

an example of Data rate vs Ec/Nt.


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4.2.3 Margins

SPER (Sub Packet Error Rate) is error of a single HSDPA HS-PDSCH transmission. SPER value will

depend on channel conditions and specific power allocation.

MarginsMargins

60%30%ITU VA120 (120 Km/h)

60%30%ITU VA30 (30 Km/h)

60%30%ITU PB3 (3 Km/h)

40%8%ITU PA3 (3 Km/h)

Average for -2.2 dB

margin

Average for 1.3 dB

margin

Channel Model

(SPER)Sub-Packet Error

Rate

A strategy can be chosen, either aggressively allocating power to ensure a higher level of success onthe first transmission or, being more conservative, allocating less power but expecting moretransmissions. The above table shows two such operating points, corresponding to a 1.3 dB and -2.2

dB margin.


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4.2.4 Scheduling Gain

Scheduling gain, defined as the ratio of what a user receives compared to a blind round robinscheduler (time division without knowledge of the channel state). Thus the scheduling gain of each

user depends on the number of active users and its ownrate statistics only.

Scheduling GainScheduling Gain


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4.2.5 Peak Throughput

The HDSPA link budget shows all factors that affect peak cell edge throughput. Some factors that

affects peak throughput are:

Peak ThroughputPeak Throughput

Cell geometry: Interference from others cell, cell placement andquality of optimization.

Number of HS-SCCHs: implemented also impacts power availablefor allocating HS-PDSCH codes, controls as well number of requiredHS-SCCHs.

Power allocation: Depending on schema applied power allocated toHSDPA will have dramatic impact on both achievable data rates andoverall capacity.

In real life, the 14 Mb/s headline figure for HSDPA is not achievable. It is physically possible to

configure such a channel but there is nowhere it could be used. The channel configuration requires

close-to-perfect link conditions. For have this rate, we need the 15 HS-PDSCH codes with the 16

QAM modulation, this means that most of the cells capacity would be consumed by this high datarate HS-DSCH configuration.


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Peak Throughput (2)Peak Throughput (2)

DL

CQI ACK TCP TCP TCPUL

16 QAMchannel

withnominaldata rateof 2.332Mb/s

Realistic peak data rates are likely to be much lower than 14 Mb/s. As an example, some test has been

done and requirement for the UE in Release 5 is based on a five-code QPSK channel with nominaldata rate of 1.6 Mb/s. The required throughput is 1.269 Mb/s. Another test requirement for the UE in

Release 5 is based on a four-code 16 QAM channel with nominal data rate of 2.332 Mb/s. The

required throughput in this case is 1.5 Mb/s. In both of these tests cases the signal needs to be 10 dBabove the noise and the UE consumes half the cell power.


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4.2.6 Considering HS-SCCH

Considering HSConsidering HS--SCCHSCCH

The downlink signaling is done through the use of the High Speed Shared Control Channel (HS-

SCCH) accompanied with each HS-DSCH. Since HS-SCCH, HS-DSCH and voice channels share thesame resources, such as power and bandwidth, control signaling is often improved at the cost ofsystem resources and capacity.

HS-SCCH is assigned to a user only when the user is scheduled. In order to provide the user with theAMC and HARQ control information in time, the SCCH is staggered with the HS-DSCH. The

HSSCCH is sent ahead of the HS-DSCH. Through successful decoding of the UE Identification (ID)

field, the intended user is informed of the upcoming HS-DSCH. This user then decodes the rest of theHS-SCCH to obtain the AMC and HARQ control information, e.g. the MCS and HARQ channel usedand prepares for the decoding of the HS-DSCH.


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Considering HSConsidering HS--SCCH (2)SCCH (2)

HS-SCCH transmit power is under control of Node B, so power level may be constant or time-variant

according to a selected power control strategy. Assignment of a constant HS-SCCH transmit power isconsidered to be an inefficient solution, which will result in a larger power overhead, i.e. loss of

capacity. However, 3GPP specifications do not explicitly specify any closed loop PC (Power Control)

modes for HS-SCCH, where UE provides feedback information on recommended transmit power for

HS-SCCH. It is typically assumed that HS-SCCH transmit power should be adjusted so that residualBLER equals approximately 1%.


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4.3 Network Planning Example

Network Configuration

First scenario

Network Planning ExampleNetwork Planning Example

Number of sites (WCDMA Release 99): 24

Clutter information: Dense Urban and Urban area

Services provided: Voice (12.2 kbps, Circuit Switched)

Video (64 Kbps, Circuit Switched)

Data (128 Kbps, Packet Switched)

Area served: 130.66 Km2


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Network Planning Example (2)Network Planning Example (2)

1. Calculating pilot Ec/Io coverage with Asset3G

This figure shows sites distribution and configuration. Ec/Io is calculated and levels are displayed inright. Map information includes different clutter information and coverage is concentrated in urban

area. Configuration sites are three cells or sectors.

Antennas, equipment and propagation models are designed for 1800 MHz.


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2. -Downlink coverage for 12.2 Kbps

Most simply of services is displayed here, 12.2 Kbps is a service that doesnt demand a lot resources

from system.


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Network Planning Example (4)Network Planning Example (4)3.- Downlink coverage for 12.2 Kbps CS and 64 kbps CS

Services for 12.2 Kbps and 64 Kbps for CS are compared. For second one is reduced compared to

12.2, however more resources are demanded for second one. This kind of services reduce capacity forother CS services.


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Network Planning Example (5)Network Planning Example (5)4.- Downlink coverage for 12.2 Kbps CS and 128 kbps PS

Same here, 128 PS is displayed with less coverage; however PS services increase capacity of system.

Coverage is reduced basically for Eb/No requirements from terminal.


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Second scenario


1. All sites have HSDPA displayed and following modulations: QPSK 1/2

QPSK 1/3

QPSK 1/4

QPSK 3/4

QPSK 4/4

16QAM 1/2

16QAM 1/3

16QAM 1/4 16QAM 3/4


2. Same services are configured (12.2 Kbps CS, 64 Kbps CS and 128 Kbps PS)

Two mobiles are set up with HSDPA capabilities: HSDPA Categories 1-2

UpLink = 64 Kbps PS

DownLink= QPSK (HSDPA Code=1, HSPDA Code=2, HSDPA Code=3, HSPDACode=4, HSDPA Code=5)

HSDPA Categories 3-4

UpLink = 64 Kbps PS

DownLink= QPSK 1/2 (HSDPA Code=1, HSPDA Code=2, HSDPA Code=3, HSPDACode=4, HSDPA Code=5)


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Downlink coverage 64 Kbps CS and HSDPA Categories 1-2

We can compare coverage and compare to 64 Kbps CS service. This mobile just include QPSKand coding. For C/I restrictions and other characteristics from HSDPA, coverage is bigger than

one offered for 64 Kbps.


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Network Planning Example (9)Network Planning Example (9) Downlink coverage 64 Kbps CS and HSDPA Categories 3-4

In this case coverage for different services is more extensive, because of less restrictive C/I

requirements and more coding capacity. Remember that just QPSK modulation is offered by this

two services, by theory if 16QAM modulation were offered must be inside QPSK modulationcoverage.


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4.3.1 Deployment options

Deployment strategy is very important and critical for HSDPA; this technology could be deployed

initially as an overlay network to an existing Release 99 one. This allows to efficient use of spectrumfor packet switched data as HSDPA mobiles are eventually introduced to market and network.

Because faster data rates of HSDPA, this network could be used as a hotspot among Release 99network; HSDPA has more cell density than traditional macrocell networks and we can improve

throughput in building applications.

User mobility also plays an important role in this deployment, HSDPA offers 16-QAM modulation,

which theoretically increases throughput compared to QPSK. However this modulation is reserved tofixed users with line of sight to Node B. Distribution and mobility of users play a significant role in

planning a HSDPA network.

1.- Coverage Options:Full Coverage

Deployment optionsDeployment options

Reduced UL coverage may arise due to interference

Interference issues need a lot of attention

Mobility has to work well

-Optional features may be required from vendors

Inefficient radio and transmission capacity allocation

Expensive to allocate HSDPA in all cells

Not suitable for cost efficient operation in the initial roll-out ofHSDPA


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Deployment options (2)Deployment options (2)

2. Coverage Options:Hotspot and Cluster Coverage


HSDPA allocated for already high R99 NRT DCH usage areas

Based on UMTS and GSM network traffic measurements

Some mobility features needed but not necessarily for the basicoperation

HSDPA DCH transitions need support from vendors

Cluster coverage may need some mobility support

Cost efficient for HSDPA roll-out as the capacity is added to thosecell having highest possibility for HSDPA traffic


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3. Coverage Options:Indoor coverage


Can potentially offer high average HSDPA throughput Dedicated carrier frequency is useful

Performance depends on SINR (Signal to Interference and Noise Ratio) conditions as inmacro cells

Good isolation (=Geometry factor) from the macro cell layer

Implementation options: Active or passive DAS, Repeaters, Indoor pico cells High number of antennas connected to the DAS (Distributed Antenna System) leading to

cable losses

High power need to be assigned to HSDPA

HSDPA indoor link budget should take into account the following Low downlink transmit power radiated by the DAS

High orthogonality reducing the level of the cells interference

Lack of soft handover gain

No fast fading margin due to no power control

Reduced slow fading margin

Potentially high level of inter-cell interference from the macro cell layer


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4. Layering Options: Single Carrier (One Carrier)


Shared UMTS carrier for HSDPA and R99 DCH traffic Node B power shared for CCH, R99 DCH, and HSDPA traffic

Effect on R99 DCH users must be considered Suitable for cells with low to medium R99 traffic

Traffic measurement data required for decisions

R99 DCH traffic QoS should not decreased due to the introduction of HSDPAinto the network -> some prioritization rules needed

CPICH Ec/No degradation -> UEs might camp on GSM

Cost efficient solutions Initial network set-up for most operators

No extra costs such as amplifiers, filters, combiners etc needed for

implementing additional carriers to Node Bs


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5. Layering Options:Multiple Carrier (Two or more Carrier)


1st carrier can be dedicated for R99 DCH traffic 2nd carrier can be fully or partly allocated for HSDPA enhanced

capacity and performance

More carriers are added to high traffic areas (Hotspots/Cluster)

Based on traffic predictions and measurements

Dedicated carrier if there is high R99 traffic in the area Node B power resources for R99 DCHs better guaranteed HSDPA users directed or handed over to a second carrier Additional BS equipment needed for 2nd carrier -> costs Fully dedicated HSDPA carrier is not a practical solution with the

current handover and load control features vendors are offering

Multiple mixed carriers with R99 & HSDPA traffic would be costefficient solutions for the operator but vendors do not have adequateservice and load sharing features


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4.3.2 Mean Cell Throughput

The HSDPA capable UE can support the use of five, 10 and 15 multicodes. Twelve new categories

have been specified for HSDPA UEs according to a number of parameters, as shown next:

Mean Cell ThroughputMean Cell Throughput

1.8QPSK only36501512

0.9QPSK only1440036502511

14.4QPSK/16QAM1728002877611510

10.2QPSK/16QAM172800204321159

7.2QPSK/16QAM134400146001108

7.2QPSK/16QAM115200146001107

3.6QPSK/16QAM672007300156

3.6QPSK/16QAM576007300155

1.8QPSK/16QAM384007300254

1.8QPSK/16QAM288007300253

1.2QPSK/16QAM288007300352

1.2QPSK/16QAM192007300351

Data Rate

(Mbps)

ModulationTotal Number

of Soft Bits

TB sizeInter TTICodesCategory

HSDPA can enable a wider coverage than R99 due to the adaptive modulation, coding and the fast

scheduler in the Node B. Works at the cell border of a R99 DCH, but the user throughput can vary

significantly

Throughput is not a single concept in HSDPA some different types, are following: average cell

throughput for single users, minimum throughput at the cell edge for a single user and averageHSDPA users throughput. HSDPA coverage can be understood as a combination of these and all of

them can have different dimensioning targets.


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The average HSDPA cell throughput and the minimum throughput at the cell edge for a single user arenot dependent on the number of simultaneous HSDPA users in the cell; this is commonly used to set

the dimensioning target for HSDPA coverage.

Mean Cell Throughput(2)Mean Cell Throughput(2)

DL


DL


DL


HSDPA throughput depends directly on the radio channel conditions, these changing rapidly all the

time due to the fast fading of the radio channel (Node B uses link adaptation). The achieved

throughput is different in every TTI (2 ms) and average throughput in a certain location can be

estimated if the average SINR is known.


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4.3.3 Coverage Statistic

Coverage StatisticCoverage Statistic

22.8517.5108.7NANA31.512.2 kbps CS

(AMR Voice)

31.81.77.1NANA3664 Kbps CS

(Video

Telephony)

29.92.311161.371536.564 Kbps PS

34.00.72.3182.7742.837384 kbps PS

Mean DCH

Power (dBm)

Standard

Deviation

(dB)

Mean Users

per cell

Standard

Deviation

(dB)

Mean

Throughput

per cell

(kbps)

Maximum

Power

Allocation

(dBm)

Service

Last table shows coverage statistics, assuming that one service is using exclusively the network. Acomplete demand was request and Monte Carlo simulations applied for determine throughput andusers supported by cell.


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4.3.4 DCH vs HSDPA

DCHDCH vsvs HSDPAHSDPA

The above chart shows impacts on Packet Switched DCH cell throughput as a result of allocating anincreasing proportion of PA power to HSDPA. The benefit of using HSDPA for PS ap