MIMO OFDM System

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    PROJECT REPORT ON:

    DESIGN OF FREQUENCY DOMAIN

    PRE-EQUALIZER FOR MULTI-USER

    MIMO IN FREQUENCY SELECTIVE

    CHANNEL USING CHANNEL

    INVERSION MODEL

    Under the Guidance of

    Er. Shuvabrata Bandopadhaya

    DEPARTMENT OF ELECTRONICS &

    TELECOMMUNICATION ENGINEERING

    SILICON INSTITUTE OF TECHNOLOGY

    SILICON HILLS, PATIA

    BHUBANESWAR - 751024.

    BIJU PATTNAIK UNIVERSITY OF TECHNOLOGY

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    DESIGN OF FREQUENCY DOMAIN PRE-

    EQUALIZER FOR MULTI-USER MIMO IN

    FREQUENCY SELECTIVE CHANNELUSING CHANNEL INVERSION MODEL

    Project report submitted in partial fulfilment of the requirements for the

    Degree of

    BACHELOR OF TECHNOLOGY (BPUT)

    In

    ELECTRONICS & TELECOMMUNICATION ENGINEERING

    BY

    AVINABA GHOSH 0901209379

    ABINASH DAS 0901209282

    SHITIKANTHA NANDA 0901209456

    SUBHRAJIT BARIK 0901209271

    MADHUSMITA SENAPATI 0901209455

    SASHANK SEKHAR BEHERA 1021209050

    Under the Guidance of

    ER. SHUVABRATA BANDOPADHAYA

    DEPARTMENT OF ELECTRONICS & TELECOMMUNICATION

    ENGINEERING

    SILICON INSTITUTE OF TECHNOLOGY

    SILICON HILLS, PATIA, BBSR-751024

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    DEPARTMENT OF ELECTRONICS & TELECOMMUNICATION ENGINEERINGSILICON INSTITUTE OF TECHNOLOGYSilicon Hills, Patia, Bhubaneswar-751024

    BIJU PATTNAIKUNIVERSITY OF TECHNOLOGY

    CERTIFICATE

    This is to certify that the project report entitled DESIGN

    OF FREQUENCY DOMAIN PRE-EQUALIZER FOR

    MULTI-USER MIMO IN FREQUENCY SELECTIVE

    CHANNEL USING CHANNEL INVERSION MODEL

    submitted by Avinaba Ghosh, Abinash Das, Shitikantha

    Nanda, Subhrajit Barik, Shasank Sekhar Behera and

    Madhusmita Senapati in partial fulfilment of the

    requirements for the Degree of Bachelor of Technology

    (BPUT) in Electronics & Telecommunication Engineering at

    Silicon Institute of Technology, Bhubaneswar is an authentic

    and bonafide work carried out by them under the supervision

    and guidance of Er. Shuvabrata Bandopadhayaduring the

    8th semester of the academic session 2012-2013.

    H.O.D (ETC) Guide

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    ACKNOWLEDGEMENT

    It gives us great pleasure to have the privilege of expressing our

    indebtedness and gratitude to our respected guide, Er. Shuvabrata

    Bandopadhaya, for his valuable guidance, deep interest, advice and

    encouragement throughout the project work. We take this opportunity to

    express oursincere thanks to him for providing the necessary facilities in

    the department.

    We are grateful to Prof. Judhistir Dash, HOD of the Electronics &

    Telecommunication Engineering Department for his positive criticism and

    valuable suggestions.

    Finally, we sincerely wish to acknowledge ourgratitude to members of the

    Silicon family for extending their help and assistance to work on this

    project.

    Date:25th April, 2012

    Place:Silicon Institute of Technology, Bhubaneswar

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    ABSTRACT

    During the past few years, there has been an explosion in wireless

    technology. This growth has opened a new dimension to future wireless

    communications whose ultimate goal is to provide universal personal and

    multimedia communication with high data rates even at high mobility.

    Because of this, the multiple-input, multiple output (MIMO) channel is

    experiencing increased interest due to the dramatic increases in capacity

    that result from adding multiple transmitter and receiver antennas to

    wireless systems. Early work in the area centered only on channels with

    flat fading characteristics. Here, it was found that channel capacity

    increases linearly with the number of antennas used. However, for all

    practical purposes, channels have frequency selective fading

    characteristics, which result in Inter Symbol Interference (ISI).

    Orthogonal Frequency Division Multiplexing (OFDM) is a technology

    which promises to mitigate ISI. In an OFDM signal the bandwidth is

    divided into many narrow and orthogonal sub-channels which are

    transmitted in parallel. Each sub-channel is typically chosen narrow

    enough to eliminate the effect of delay spread.

    The purpose of this project is to create and simulate a MIMO-OFDM

    combined system, in a frequency selective channel, which will not only

    increase channel capacity but reduce ISI as well. The system will then be

    extended to a multi-user model and the Bit Error Rate (BER) performance

    of the system at different SNR will be computed and analyzed.

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    CONTENTS

    TOPIC PAGE NO.

    Multiple Input Multiple Output (MIMO)

    Orthogonal Frequency Division Multiplexing(OFDM)

    Channel Estimation

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    Multiple-Input Multiple-Output

    (MIMO)The last ten years have witnessed the transition of multiple-input multiple-

    output (MIMO) communication from a theoretical concept to a practical

    technique for enhancing performance of wireless networks [1]. Point-to-

    point (single user) MIMO communication promises large gains for both

    channel capacity and reliability, essentially via the use of space-time codes

    (diversity gain oriented) combined with stream multiplexed transmission

    (rate maximization oriented). In such a traditional single user view of

    MIMO systems, the extra spatial degrees of freedom brought by the use of

    multiple antennas are exploited to expand the dimensions available for

    signal processing and detection, thus acting mainly as a physical (PHY)

    layer performance booster. In this approach the link layer protocols for

    multiple accesses (uplink and downlink) indirectly reap the performance

    benefits of MIMO antennas in the form of greater per-user rates, or more

    reliable channel quality, despite not requiring full awareness of the MIMO

    capability.

    The recent development of cross-layer techniques, aimed at the joint design

    of the PHY layers modulation and link layers multiple access protocols

    has begun to shatter this view. This is especially true in MIMO networking

    where the positive role played by the spatial dimension on multiple

    accesses and scheduling is now being recognized, replacing the simplistic

    view of MIMO as a pure PHY technology. A better understanding of the

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    impact of MIMO antennas on multiuser communications is, by large, due

    to progress in the field of multiuser information theory [2]. Fundamental

    recent results in this area have hinted at how deeply connected PHY layer

    modulation/coding and link layer resource allocation and scheduling can

    be, at least when having overall optimum system design as objective. One

    interesting example of this is the conflict and degradation that may arise

    from certain uncoordinated designs at the PHY and link layer when both

    layers attempt to extract diversity (e.g. use of channel-hardening [3] single-

    user space-time codes at the PHY combined with multiuser diversity

    scheduling at the link layer). Multiuser MIMO (MU-MIMO) information

    theory advocates for the use of spatial sharing of the channel by the users.

    Such a multiple access protocol implies an extra hardware cost (antennas

    and filters) but does not involve any bandwidth expansion, unlike say time-

    division (TDMA) or code-division (CDMA) multiple access. In spatialmultiple access, the resulting multiuser interference is handled by the

    multiple antennas which in addition to providing per-link diversity also

    give the degrees of freedom necessary for spatial separation of the users. In

    practice, MU-MIMO schemes with good complexity/performance trade-

    offs can be implemented to realize these ideas. On the uplink or multiple

    access channel (MAC), the development of MU-MIMO techniques appears

    as a generalization of known single user MIMO concepts to the multiuser

    case. As usual in information theory, the downlink or broadcast channel

    (BC) case is by far the most challenging one. Information theory reveals

    that the optimum transmit strategy for the MU-MIMO broadcast channel

    involves a theoretical pre interference cancellation technique known as

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    dirty paper coding (DPC) combined with an implicit user scheduling and

    power loading algorithm. In that respect, the role played by seminal papers

    such as [4] was fundamental. In turn, several practical strategies have

    recently been proposed to approach the rates promised in the MU-MIMO

    channel involving concepts such as linear and non-linear channel-aware

    precoding, channel state feedback, and multiuser receivers. A number of

    corresponding scheduling and user selection algorithms have also been

    proposed, leveraging features of different MU-MIMO strategies.

    Multiuser MIMO techniques and performance have begun to be intensely

    investigated because of several key advantages over single user MIMO

    communications.

    MU-MIMO appears more immune to most of propagation limitations

    plaguing single user MIMO communications such as channel rank loss or

    antenna correlation. Although increased correlation still affects per-user

    diversity, this