HSDPA/HSUPA for Beginners · Confidential –Restricted Distribution © eXplanoTech Ltd., Asset Id. 100210034100 12 HSDPA Background HSDPA is a major feature of Release 5 with following

HSDPA/HSUPA for Beginnersv1.0.0

By

eXplanoTech Ltd.Date: 10/02/2010

Confidential – Restricted Distribution© eXplanoTech Ltd., Asset Id. 100210034100

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Important Notice!

The training material you are reading is protected by copyright law. This material should only be read in the organisation for which it has been produced. This cannot be distributed outside of the organisation or distributed or made available on the Internet. Apart from fair dealing for the purposes of research or private study, as permitted under the Copyright, Designs and Patents Act 1988, this manual may only be reproduced or transmitted in any form or by any means with the prior permission in writing of eXplanoTech Limited.


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Agenda /Contents

❑ Course Introduction

❑High Speed Downlink Packet Access (HSDPA)▪ HSDPA Introduction

▪ HSDPA Basic Principles

▪ HSDPA Architecture

❑High Speed Uplink Packet Access (HSUPA)▪ HSUPA Introduction

▪ HSUPA Basic Principles

▪ HSUPA Architecture

Course Introduction


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Technological Evolution

❑ The biggest focus at present is on the speed of data

❑ WiMAX is seen as the biggest threat to existing mobile technologies


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Data overtaking Voice


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UMTS-HSPA Timeline (now)


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UMTS-HSPA Timeline (2014)


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Release 5 & 6

❑ Release ’99 / 4▪ DSCH → PDSCH (with associated DPCH)

▪ CPCH → PCPCH

❑ Release 5▪ DSCH and CPCH removed from FDD specifications

▪ HSDPA introduced

▪ HS-DSCH → HS-PDSCH / HS-SCCH / HS-DPCCH

❑ Release 6▪ HSUPA

▪ E-DCH / EDPDCH / EDPCCH

High Speed Downlink Packet Access (HSDPA)

HSDPA Introduction


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HSDPA Background

❑HSDPA is a major feature of Release 5 with following targets

▪ Establish a more spectral efficient way of using DL resources providing data rates beyond 2 Mbit/s

▪ Optimize interactive & background traffic, support streaming service

▪ Design for indoor & urban environment, but not restricted

▪ Techniques compatible with advanced antenna and receivers

❑ Standardization started in June 2000

▪ Broad forum of companies


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More than 400* HSPA devices in market


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HSDPA Introduction

❑HSDPA was standardised as 3GPP release 5

❑ The HSDPA peak data rate available in the terminals is initially 1.8Mbps and will

❑ increase to 3.6 and 7.2 Mbps during 2006 and 2007, and potentially beyond 10Mbps.

❑ Current WCDMA network can be upgraded to support HSDPA

❑HSDPA will▪ Increase peak data rates upto 14Mbps

▪ Reduce the round trip delay

▪ Will increase the UTRAN network capacity


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Motivation: File Download Performance with HSDPA


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Motivation: Reduced Latency


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HSDPA what comes in? & What goes out?

❑ Two fundamental features of WCDMA are disabled:

▪ Variable SF

▪ Fast Power Control

❑ These two features are replaced by

▪ Adaptive Modulation and Coding (AMC)

▪ Fast retransmission strategy (HARQ)

▪ Scheduling Algorithm


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Important changes with HSDPA


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New Channels Introduced in HSDPA (R5) - 1

❑HS-DSCH (High Speed Down link Shared Channel)▪ TO support the HS-DSCH Operation

▪ Two Control Channels are added

❑ HS-SCCH (High Speed Shared Control Channel)

▪ DL channel

❑ HS- DPCCH (High Speed Dedicated Physical

Control Channel)

▪ UL Channel


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New Channels Introduced in HSDPA (R5) - 2

HSDPA Basic Principles


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Shared Channel Transmission - 1

❑Dedicated channel▪ User resources

assigned at ”call setup”

▪ Independent of instantaneous traffic situation

❑Shared channel

▪ Dynamic sharing of common rerouce

▪ Adapts to instantaneous traffic situation


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Shared Channel Transmission - 2

❑ Channelization codes at a fixed spreading factor of SF = 16

❑ Up to 15 codes in parallel

❑ OVSF channelization code tree allocated by CRNC

❑ HSDPA codes autonomously managed by NodeB MAC-hs scheduler

❑ Additionally, HS-SCCH codes with SF = 128 (number equal to simult. UE)


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Higher Order Modulation (HOM)

❑ 16QAM may be used as a complement to QPSK

❑ 16QAM allows for twice the peak data rate compared to QPSK

❑ 16QAM more sensitive to interference▪ Higher data rate in good radio channel conditions (high C/I,

Little or no dispersion, Low speed)

– e.g. Close to cell site & Micro/Indoor cells


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Short 2ms TTI

❑ Reduced round trip delay on the air interface

❑ Enables HSDPA features to operate at 500 times per second!▪ Fast Link Adaptation

▪ Fast Radio Channel dependent Scheduling

▪ Fast hybrid ARQ with soft combining


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Fast HARQ with Soft Combining - 1

❑ Fast retransmissions of erroneous packets processed in the NodeB▪ Reduced round trip delay on the air interface

❑ Soft combining of multiple transmission attempts in the UE▪ Improved performance


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Fast HARQ with Soft Combining - 2

❑ Incremental redundancy


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Fast Link Adaptation - 1

❑ Adjust transmission parameters to match instantaneous radio channel conditions▪ Path loss and shadowing

▪ Interference variations

▪ Fast multipath fading

❑HSDSCH is rate controlled▪ Encoding rate, number of channelization codes &

modulation type adapted based on available power

▪ Adaptation on 2 ms TTI basis = 500 times/sec!


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Fast Link Adaptation – 2HSDSCH Power Utilization

❑ No need for extra spectrum/carrier

❑ Voice and data on same carrier


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Fast Channel dependent Scheduling - 1

❑ Scheduling = which UE to transmit to at a given time instant

❑ Basic idea:▪ Transmit to users based on radio channel quality, targeting fading

peaks

▪ May lead to large variations in data rate between users

▪ Tradeoff: fairness vs. cell throughput


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Fast Channel dependent Scheduling - 2

❑ Round Robin (RR)

▪ Cyclically assign the channel to users without taking channel conditions into account

▪ Simple but poor performance

❑ Max C/I

▪ Assign the channel to the user with the best channel quality

▪ High system throughput but not fair

❑ Proportional Fair (PF)

▪ Assign the channel to the user with the best relative channel quality

▪ High throughput, fair


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HSDPA UE Categories


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HSDPA Data Rate Calculation

HSDPA Architecture


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HSDPA Architecture Illustration


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HSDPA – Further Reading

❑ 3GPP TR 25.855 - HSDPA; Overall UTRAN Description; Release 5

❑ 3GPP TR 25.858 - HSDPA; Physical Layer Aspects; Release 5

❑ 3GPP TR 29.950 - UTRA High Speed Downlink Packet Access; Release 4

❑ 3GPP TR 25.877 - HSDPA: Iub/Iur Protocol Aspects

❑ 3GPP TR 25.899 - HSDPA Enhancements; Release 5

High Speed Uplink Packet Access (HSUPA)

HSUPA Introduction


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HSUPA Overview

❑3GPP Release 6▪ Enhanced Dedicated Channel (E-DCH)

❑Also known as 3.75G (HSDPA = 3.5G)

❑Peak data rate of 5.74 Mbps▪ Practical data rates initially will be 1-2 Mbps

❑Reduced retransmission delay▪ Node-B scheduling

❑Better interference management

❑UL packet data throughput increased▪ Better resource allocation/reallocation

❑Not supported for RLC-TM


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Key Enablers

❑Hybrid ARQ▪ Multiple Stop-and-Wait processes

❑Smaller TTI of 2 ms

❑Regular and timely feedback

❑Retransmission at MAC

❑Scheduled and unscheduled transmissions

❑Soft handover supported


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Feature Comparison

UL DCH HSUPA HSDPA

Variable SF Yes Yes No

Multicode Transmission Yes Yes Yes

Fast Power Control Yes Yes No

Soft Handover Yes Yes No

Adaptive Modulation No

BPSK

No

BPSK

Yes

QPSK / 16QAM

BTS Scheduling No Yes Yes

Fast L1 HARQ No Yes Yes

Data Delivery Timing - Synchronous Asynchronous

Non-scheduled Transmission No Yes No


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R99 Resource Allocation

RNCUE Requests resources

RNC Allocates resources

UE Uses resources

Unused resources –

(cannot be re-allocated)

actual

loading

impact


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HSUPA Resource Allocation

RNCUE Requests resources

RNC Allocates resources

UE Uses resources

actual

loading

impact

Node B ‘fine tunes’

resource allocations

Resources allocated to

multiple users

HSUPA Basic Principles


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HSUPA: Node B Scheduling - 1

❑ RNC: resource allocation per cell

❑ UE requests resources (buffer status is reported)

❑NodeB: resource allocation per UE

❑ UE: makes use of allocated resources


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HSUPA: Node B Scheduling - 2


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HARQ with Soft Combining

❑HSUPA has HARQ processes just like HSDPA, but in opposite direction - UE sends, Node B ACKs/NACKs

❑ 4 HARQ processes for 10 ms TTI, 8 for 2 ms TTI

❑ Stop/wait operation -fixed round trip time (40 ms or 16 ms)


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HSUPA: Features and Effects


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HSUPA UE Categories

HSUPA Architecture


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HSUPA Architecture Illustration


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MAC-e/es

❑ N/w side ❑ UE side


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HSUPA – Further Reading

❑ 3GPP TS 25.309 - FDD Enhanced Uplink; Overall description; Stage 2; Release 6

❑ 3GPP TR 25.896 - Feasibility Study for Enhanced Uplink for UTRA FDD; Release 6

❑ 3GPP TR 25.808 - FDD Enhanced Uplink; Physical Layer Aspects


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Books worth reading

Documents

HSDPA/HSUPA for Beginners · Confidential –Restricted Distribution © eXplanoTech Ltd., Asset Id. 100210034100 12 HSDPA Background HSDPA is a major feature of Release 5 with following