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  • On Design and Analysis of Channel Aware LTE Uplink and Downlink Scheduling Algorithms

    by

    Aswin Kanagasabai

    7553177

    A thesis submitted to the

    Faculty of Graduate and Postdoctoral Studies

    in partial fulfillment of the requirements for the degree of

    MASTER OF APPLIED SCIENCE

    in Electrical and Computer Engineering

    Ottawa-Carleton Institute for Electrical and Computer Engineering

    School of Electrical Engineering and Computer Science

    University of Ottawa

    Ottawa, Ontario K1N 6N5, Canada

    April 2015

    © Aswin Kanagasabai, Ottawa, Canada, 2015

  • II

    Abstract

    In the past two decades, there has been a drastic increase in the mobile traffic, which is

    caused by the improved user experience with smart phones and its applications. In LTE

    system, the packet scheduler plays a vital role in the effective utilization of the resources.

    This field is not standardized and has immense scope of improvement, allowing vendor-

    specific implementation. The work presented in this thesis focuses on designing new

    scheduling algorithms for uplink and downlink to effectively distribute resources among the

    users. LTE scheduling can be categorized into two extremes, namely, Opportunistic

    scheduling and Fairness scheduling. The Best Channel Quality Indicator (BCQI) algorithm

    falls under the former category while Proportional Fairness (PF) algorithm under the later.

    BCQI algorithm provides high system throughput than PF algorithm, however, unlike BCQI

    algorithm, PF algorithm considers users with poor channel condition for allocation process.

    In this work, two new scheduling disciplines referred as Opportunistic Dual Metric (ODM)

    Scheduling Algorithm is proposed for uplink and downlink respectively.

    The objective of the algorithm is to prioritize the users with good channel condition for

    resource allocation, at the same time not to starve the users with poor channel conditions.

    The proposed algorithm has two resource allocation matrices, H1 and H2, where H1 is

    throughput-centric and H2 is fairness-centric. The uplink algorithm uses the two resource

    allocation matrices to allocate the resources to the users and to ensure contiguous resource

    allocation. The downlink algorithm is an extension of the proposed uplink algorithm

    avoiding uplink constraints. The downlink algorithm employs the two resource distribution

    matrices to provide an efficient resource allocation by expanding the allocation for the users

    considering intermittent resources. The performance of ODM is measured in terms of

    throughput, fairness. Additionally, the uplink algorithm is analysed in terms of transmit

    power. From the results it is observed that the proposed algorithms has better trade-off in

    terms of all the performance parameters than PF scheduler and BCQI scheduler.

  • III

    Acknowledgement

    I would like to use this opportunity to express my gratitude to my thesis supervisor,

    Dr. Amiya Nayak, for his valuable guidance, patience and support which led me in the right

    path for the successful completion of this work.

    I would also like to thank my friends and family for their understanding,

    unconditional love and support.

  • IV

    TABLE OF CONTENT

    1 INTRODUCTION ............................................................................................................................1

    1.1 INTRODUCTION .............................................................................................................................1

    1.2 MOTIVATION ................................................................................................................................1

    1.3 OBJECTIVE ...................................................................................................................................2

    1.4 CONTRIBUTION .............................................................................................................................3

    1.5 THESIS OUTLINE ............................................................................................................................4

    2 BACKGROUND ..............................................................................................................................6

    2.1 INTRODUCTION .............................................................................................................................6

    2.2 LTE NETWORK ARCHITECTURE ..........................................................................................................7

    2.3 RADIO INTERFACE TECHNOLOGY ........................................................................................................9

    2.3.1 PHYSICAL RESOURCE ORGANIZATION ...................................................................................................... 11

    2.4 LTE PROTOCOL STACK .................................................................................................................. 12

    2.4.1 USER PLANE PROTOCOL STACK .............................................................................................................. 13

    2.4.2 CONTROL PLANE PROTOCOL STACK ........................................................................................................ 21

    2.5 LTE SCHEDULER .......................................................................................................................... 25

    2.5.1 DESIGN ASPECTS ................................................................................................................................. 27

    2.5.2 MODEL OF LTE PACKET SCHEDULER ....................................................................................................... 28

    2.5.3 SCHEDULING ALGORITHM ..................................................................................................................... 30

    2.5.4 TYPES OF SCHEDULING ALGORITHM ........................................................................................................ 33

    2.6 SUMMARY ................................................................................................................................. 36

    3 EVALUATION OF SCHEDULING ALGORITHMS ............................................................................... 37

  • V

    3.1 INTRODUCTION ........................................................................................................................... 37

    3.2 PERFORMANCE PARAMETERS ......................................................................................................... 37

    3.2.1 SYSTEM THROUGHPUT ......................................................................................................................... 38

    3.2.2 JAIN’S FAIRNESS INDEX ......................................................................................................................... 38

    3.2.3 THROUGHPUT TO POWER RATIO ............................................................................................................ 40

    3.3 SIMULATION SETUP ...................................................................................................................... 41

    3.4 RESULTS .................................................................................................................................... 42

    3.4.1 THROUGHPUT ANALYSIS ....................................................................................................................... 42

    3.4.2 FAIRNESS ANALYSIS.............................................................................................................................. 43

    3.4.3 THROUGHPUT TO POWER RATIO ANALYSIS .............................................................................................. 44

    3.5 CONCLUSION .............................................................................................................................. 47

    4 OPPORTUNISTIC DUAL METRIC SCHEDULING ALGORITHMS FOR LTE UPLINK AND DOWNLINK ...... 48

    4.1 INTRODUCTION ........................................................................................................................... 48

    4.2 OPPORTUNISTIC DUAL METRIC STRATEGY ......................................................................................... 48

    4.3 OPPORTUNISTIC DUAL METRIC SCHEDULING ALGORITHM FOR LTE UPLINK ................................................ 49

    4.3.1 CONSTRAINTS ..................................................................................................................................... 49

    4.3.2 EVALUATION OF THE PARAMETERS Α AND Β FOR UPLINK............................................................................. 51

    4.3.3 PROPOSED ALGORITHM FOR LTE UPLINK ................................................................................................ 52

    4.4 OPPORTUNISTIC DUAL METRIC SCHEDULING ALGORITHM FOR LTE DOWNLINK ........................................... 54

    4.4.1 CONSTRAINTS ..................................................................................................................................... 54

    4.4.2 SEARCH-TREE PATTERN-BASED SCHEDULING STRATEGY ............................................................................. 56

    4.4.3 EVA