LDPC code-based bandwidth efficient coding schemes for wireless communications /

Bibliographic Details
Main Author: Sankar, Hari
Other Authors: Narayanan, Krishna R. (Thesis advisor)
Format: Thesis eBook
Language:English
Published: [College Station, Tex.] : [Texas A&M University], [2010]
Subjects:
Online Access:Link to OAK Trust copy

MARC

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099 |a 2006  |a Dissertation  |a 1969.1/ETD-TAMU-1780 
100 1 |a Sankar, Hari. 
245 1 0 |a LDPC code-based bandwidth efficient coding schemes for wireless communications /  |c by Hari Sankar. 
264 1 |a [College Station, Tex.] :  |b [Texas A&M University],  |c [2010] 
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500 |a "Major Subject: Electrical Engineering" 
500 |a Title from author supplied metadata (automated record created 2010-03-12 12:08:51). 
502 |b Doctor of Philosophy  |c Texas A&M University  |d 2006  |o http://hdl.handle.net/1969.1/ETD-TAMU-1780 
504 |a Includes bibliographical references. 
516 |a Text (Dissertation) 
520 3 |a This dissertation deals with the design of bandwidth-efficient coding schemes with Low-Density Parity-Check (LDPC) for reliable wireless communications. Code design for wireless channels roughly falls into three categories: (1) when channel state information (CSI) is known only to the receiver (2) more practical case of partial CSI at the receiver when the channel has to be estimated (3) when CSI is known to the receiver as well as the transmitter. We consider coding schemes for all the above categories. For the first scenario, we describe a bandwidth efficient scheme which uses highorder constellations such as QAM over both AWGN as well as fading channels. We propose a simple design with LDPC codes which combines the good properties of Multi-level Coding (MLC) and bit-interleaved coded-modulation (BICM) schemes. Through simulations, we show that the proposed scheme performs better than MLC for short-medium lengths on AWGN and block-fading channels. For the first case, we also characterize the rate-diversity tradeoff of MIMO-OFDM and SISO-OFDM systems. We design optimal coding schemes which achieve this tradeoff when transmission is from a constrained constellation. Through simulations, we show that with a sub-optimal iterative decoder, the performance of this coding scheme is very close to the optimal limit for MIMO (flat quasi-static fading), MIMO-OFDM and SISO OFDM systems. For the second case, we design non-systematic Irregular Repeat Accumulate (IRA) codes, which are a special class of LDPC codes, for Inter-Symbol Interference (ISI) fading channels when CSI is estimated at the receiver. We use Orthogonal Frequency Division Multiplexing (OFDM) to convert the ISI fading channel into parallel flat fading subchannels. We use a simple receiver structure that performs iterative channel estimation and decoding and use non-systematic IRA codes that are optimized for this receiver. This combination is shown to perform very close to a receiver with perfect CSI and is also shown to be robust to change in the number of channel taps and Doppler. For the third case, we look at bandwidth efficient schemes for fading channels that perform close to capacity when the channel state information is known at the transmitter as well as the receiver. Schemes that achieve capacity with a Gaussian codebook for the above system are already known but not for constrained constellations. We derive the near-optimum scheme to achieve capacity with constrained constellations and then propose coding schemes which perform close to capacity. Through linear transformations, a MIMO system can be converted into non-interfering parallel subchannels and we further extend the proposed coding schemes to the MIMO case too. 
500 |a Electronic resource. 
650 4 |a Major electrical engineering. 
653 |a capacity 
653 |a turbo codes 
653 |a OFDM 
653 |a adaptive modulation 
653 |a LDPC 
653 |a Communications 
653 |a Wireless 
653 |a MIMO 
700 1 |a Narayanan, Krishna R.,  |e thesis advisor. 
856 4 0 |u http://hdl.handle.net/1969.1/ETD-TAMU-1780  |z Link to OAK Trust copy  |t 0 
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952 f f |a Texas A&M University  |b College Station  |c Electronic Resources  |d Available Online  |t 0  |e 2006 Dissertation 1969.1/ETD-TAMU-1780  |h Other scheme 
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