Dedicated Channel Capacity of a WCDMA System with HSDPA .Dedicated Channel Capacity of a WCDMA...

download Dedicated Channel Capacity of a WCDMA System with HSDPA .Dedicated Channel Capacity of a WCDMA System

of 58

  • date post

    05-Jul-2018
  • Category

    Documents

  • view

    224
  • download

    10

Embed Size (px)

Transcript of Dedicated Channel Capacity of a WCDMA System with HSDPA .Dedicated Channel Capacity of a WCDMA...

  • Dedicated Channel Capacity of a

    WCDMA System with HSDPA

    SUJATA BHATTACHARYA

    Masters Degree ProjectStockholm, Sweden 2005

  • Dedicated Channel Capacity of a

    WCDMA System with HSDPA

    SUJATA BHATTACHARYA

    Masters Degree Project

    May 2005

    TRITAS3RST0512ISSN 14009137

    ISRN KTH/RST/R--05/12--SE

    Radio Communication Systems LaboratoryDepartment of Signals, Sensors and Systems

  • Abstract

    Keeping an eye on the future upcoming demands for mobile applications, 3GPPhas the target to enhance the downlink packet data rate in many folds. As aresult, WCDMA specifications have been evolved with the addition of a newfeature called HSDPA (High Speed Downlink Packet Access) in Release 5. Thegoal of HSDPA has been to increase the system capacity by increasing the datarate and reduce the round trip delay. The increase of system capacity has beenachieved by dynamic sharing of code resource and certain amount of power.

    A number of research papers have shown that HSDPA will enhance WCDMAsystem with the fulfillment of the above objective. As per the business forcast,HSDPA will start getting deployed towards the end of this year (2005). How-ever, in a real deployment scenario, it may happen that some of the cells areimplemented with HSDPA and some are not yet; what will happen to the capac-ity of those cells without HSDPA? When HSDPA is implemented in a cell, thebase station uses more power, imparting more interference to the neighbouringcells, thus affecting their dedicated channel capacity. In addition to the higherpower, if the availability of data in the HSDPA channel varies, then the inter-ference to the neighbouring cell might be larger and fluctuating, in turn, thededicated channel capacity of the neighbouring cells might be affected.

    This scenario has been studied in this master thesis. Mainly, it has beenstudied how is the dedicated channel capacity of a cell without HSDPA affectedby the introduction of an HSDPA channel in adjacent cell. Does this influencedepend on the data traffic on the HSDPA channel?

    With the simple system model used, it has been observed that though there isa change in the capacity of the system after implementing HSDPA in adjacentcells, the variation is negligible. It has been found that the decrease in thededicated channel capacity is more if the HSDPA data traffic is larger. Thefluctuating data in HSDPA channel has not degraded the capacity further; itis only the higher power, which has affected the dedicated channel capacity.However, in all these cases, variation can be considered as negligible. So, ithas been concluded that there is no impact on the capacity of cells which arenot with HSDPA after implementing HSDPA in adjacent cells. Considering thelimitations in this study, it has been suggested to study this aspect further byusing a more complex system model to find out the reality.

    iii

  • Acknowledgements

    I would like to convey my deepest gratitude to my advisor, Bogdan Timus, whohas guided me in pursuing my thesis. I sincerely appreciate his effort to helpme in my work. I would like to convey my thanks to Prof.Dr. Jens Zander forhis kind consent of becoming my examiner for this master thesis.

    In addition, I would like to express my indebtedness to Prof.Dr. MikaelSkoglund, Program Director, Master program in Wireless systems for giving methe opportunity to join the master program in which this thesis is a part of thecurriculum. I would like to thank Dr. Ben Slimane and Dr. Bo Karlson fortheir guidance and motivation to join the master program.

    I am in deed thankful to Dr. Muhammad Kazmi from Ericsson for hiscomments to my thesis during the study period. Also I am thankful to all othercollegues in Radio Communication Systems department for their kind support.Lastly, I acknowledge the support and inspiration given by my family in pursuingand achieving this work.

    v

  • Contents

    1 Introduction 1

    1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

    1.2 Thesis Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . 2

    1.3 Problem Definition . . . . . . . . . . . . . . . . . . . . . . . . . . 2

    1.4 Previous Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

    1.5 Report Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

    2 HSDPA Overview 7

    2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

    2.2 Channels in HSDPA . . . . . . . . . . . . . . . . . . . . . . . . . 7

    2.2.1 HS-DSCH . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

    2.2.2 HS-SCCH . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

    2.2.3 HS-DPCCH . . . . . . . . . . . . . . . . . . . . . . . . . . 9

    2.2.4 DPCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

    2.3 Fast Link Adaptation . . . . . . . . . . . . . . . . . . . . . . . . 9

    2.4 Hybrid ARQ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

    2.5 Fast Scheduling . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

    2.6 Power Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

    3 System Model 13

    3.1 Network Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

    3.1.1 Cell Deployment Model . . . . . . . . . . . . . . . . . . . 13

    3.1.2 Propagation Model . . . . . . . . . . . . . . . . . . . . . . 13

    3.1.3 Handover . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

    3.1.4 HSDPA Model . . . . . . . . . . . . . . . . . . . . . . . . 15

    3.1.5 Traffic Model . . . . . . . . . . . . . . . . . . . . . . . . . 15

    3.1.6 Power Control Model . . . . . . . . . . . . . . . . . . . . 16

    3.1.7 Interference Model . . . . . . . . . . . . . . . . . . . . . . 17

    3.1.8 Receiver Model . . . . . . . . . . . . . . . . . . . . . . . . 18

    3.2 System Quality Measure . . . . . . . . . . . . . . . . . . . . . . . 19

    4 Results 21

    4.1 Adjacent Cell Dissatisfaction . . . . . . . . . . . . . . . . . . . . 21

    4.2 HSDPA Admission Threshold . . . . . . . . . . . . . . . . . . . . 24

    4.3 Comparison of DCH Capacity . . . . . . . . . . . . . . . . . . . . 28

    vii

  • viii Contents

    5 Conclusion 31

    5.1 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315.2 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

    References 33

    A Receiver Model Details 35

    B UTRAN Overview 39

    B.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39B.2 Power Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

    B.2.1 Inner loop Power control . . . . . . . . . . . . . . . . . . . 42B.2.2 Outer loop Power Control . . . . . . . . . . . . . . . . . . 42

  • List of Figures

    1.1 System Example- Combination of cells-with/without HSDPA . . 31.2 Capacity variation after HSDPA implementation in adjacent cells 4

    2.1 Uplink HS-DPCCH . . . . . . . . . . . . . . . . . . . . . . . . . . 9

    3.1 Network Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143.2 Single Stage Markov Chain . . . . . . . . . . . . . . . . . . . . . 16

    4.1 Adjacent Cell Dissatisfaction (TPCdelay = 0) . . . . . . . . . . . 224.2 Adjacent Cell Dissatisfaction (TPCdelay = 2) . . . . . . . . . . . 234.3 BSPower Distribution for Reference System at different loads . . 254.4 System Dissatisfaction for different HSPWR threshold . . . . . . 264.5 Adjacent Cell Dissatisfaction for different HSPWR threshold . . 274.6 Comparison of DCH Capacity of adjacent cells without HSDPA . 29

    A.1 Probability of BSpwr reaching maximum BSpwr-Ref Sys . . . . 36A.2 Average Base Station Power-Ref Sys . . . . . . . . . . . . . . . . 37A.3 Determination of Reference SIR- Ref Sys . . . . . . . . . . . . . 38

    B.1 UMTS architecture . . . . . . . . . . . . . . . . . . . . . . . . . . 40B.2 Radio frame for Uplink dedicated physical channel . . . . . . . . 40B.3 Radio frame for Downlink Dedicated Physical Channel . . . . . . 41

    ix

  • List of Abbreviations

    3GPP 3rd Generation Partnership ProjectBCCH Broadcast Control ChannelBCH Broadcast ChannelBER Bit Error RateBLER Block Error RateBS Base StationCCCH Common Control ChannelCPCH Common Packet ChannelCTCH Common Traffic ChannelDCH Dedicated ChannelDCCH Dedicated Control ChannelDSCH Downlink Shared ChannelDTCH Dedicated Traffic ChannelFACH Forwardlink Access ChannelHARQ Hybrid Automatic Repeat RequestHSDPA High Speed Downlink Packet AccessHS-DSCH High Speed Downlink Shared ChannelPCCH Paging Control ChannelPCH Paging ChannelQAM Quadrature Amplitude ModulationQPSK Quadrature Phase Shift KeyingRACH Random Access ChannelSHCCH Shared Control ChannelSIR Signal to Interference RatioTCP Transmission Control ProtocolTTI Transmission Time IntervalUE User EquipmentUMTS Universal Mobile Telecommunications SystemUTRAN UMTS Terrestrial Radio Access NetworkWCDMA Wideband Code Division Multiple Access

    xi

  • Chapter 1

    Introduction

    1.1 Background

    The WCDMA specifications up to Release 99 & Release 4 support data ratesup to 2 Mb/s in indoor/small-cell-outdoor environments and up to 384 Kb/swith wide area coverage for packet-switched data [1], [2]. However, this fig-ure has been felt as insufficient in the near future considering the upcominggrowing-demands for packet-data services, primarily in the downlink. There-fore, the WCDMA specifications have been evolved in two stages within 3GPPin order to enhance higher packet-data rate. The first step has been to improvethe downlink capacity and the second step targets for the uplink [3]. The en-hancement of downlink capacity of WCDMA system has been described as afeature known as High Speed Downlink Packet Ac