Uppal, Momin Ayub (2010-08). Coding for Cooperative Communications. Doctoral Dissertation. Thesis uri icon

abstract

  • The area of cooperative communications has received tremendous research interest in recent years. This interest is not unwarranted, since cooperative communications promises the ever-so-sought after diversity and multiplexing gains typically associated with multiple-input multiple-output (MIMO) communications, without actually employing multiple antennas. In this dissertation, we consider several cooperative communication channels, and for each one of them, we develop information theoretic coding schemes and derive their corresponding performance limits. We next develop and design practical coding strategies which perform very close to the information theoretic limits. The cooperative communication channels we consider are: (a) The Gaussian relay channel, (b) the quasi-static fading relay channel, (c) cooperative multiple-access channel (MAC), and (d) the cognitive radio channel (CRC). For the Gaussian relay channel, we propose a compress-forward (CF) coding strategy based on Wyner-Ziv coding, and derive the achievable rates specifically with BPSK modulation. The CF strategy is implemented with low-density parity-check (LDPC) and irregular repeataccumulate codes and is found to operate within 0.34 dB of the theoretical limit. For the quasi-static fading relay channel, we assume that no channel state information (CSI) is available at the transmitters and propose a rateless coded protocol which uses rateless coded versions of the CF and the decode-forward (DF) strategy. We implement the protocol with carefully designed Raptor codes and show that the implementation suffers a loss of less than 10 percent from the information theoretical limit. For the MAC, we assume quasi-static fading, and consider cooperation in the low-power regime with the assumption that no CSI is available at the transmitters. We develop cooperation methods based on multiplexed coding in conjunction with rateless codes and find the achievable rates and in particular the minimum energy per bit to achieve a certain outage probability. We then develop practical coding methods using Raptor codes, which performs within 1.1 dB of the performance limit. Finally, we consider a CRC and develop a practical multi-level dirty-paper coding strategy using LDPC codes for channel coding and trellis-coded quantization for source coding. The designed scheme is found to operate within 0.78 dB of the theoretical limit. By developing practical coding strategies for several cooperative communication channels which exhibit performance close to the information theoretic limits, we show that cooperative communications not only provide great benefits in theory, but can possibly promise the same benefits when put into practice. Thus, our work can be considered a useful and necessary step towards the commercial realization of cooperative communications.
  • The area of cooperative communications has received tremendous research interest

    in recent years. This interest is not unwarranted, since cooperative communications

    promises the ever-so-sought after diversity and multiplexing gains typically

    associated with multiple-input multiple-output (MIMO) communications, without

    actually employing multiple antennas. In this dissertation, we consider several cooperative

    communication channels, and for each one of them, we develop information

    theoretic coding schemes and derive their corresponding performance limits. We next

    develop and design practical coding strategies which perform very close to the information

    theoretic limits.

    The cooperative communication channels we consider are: (a) The Gaussian relay

    channel, (b) the quasi-static fading relay channel, (c) cooperative multiple-access

    channel (MAC), and (d) the cognitive radio channel (CRC). For the Gaussian relay

    channel, we propose a compress-forward (CF) coding strategy based on Wyner-Ziv

    coding, and derive the achievable rates specifically with BPSK modulation. The CF

    strategy is implemented with low-density parity-check (LDPC) and irregular repeataccumulate

    codes and is found to operate within 0.34 dB of the theoretical limit. For

    the quasi-static fading relay channel, we assume that no channel state information

    (CSI) is available at the transmitters and propose a rateless coded protocol which

    uses rateless coded versions of the CF and the decode-forward (DF) strategy. We

    implement the protocol with carefully designed Raptor codes and show that the implementation suffers a loss of less than 10 percent from the information theoretical limit. For

    the MAC, we assume quasi-static fading, and consider cooperation in the low-power

    regime with the assumption that no CSI is available at the transmitters. We develop

    cooperation methods based on multiplexed coding in conjunction with rateless

    codes and find the achievable rates and in particular the minimum energy per bit to

    achieve a certain outage probability. We then develop practical coding methods using

    Raptor codes, which performs within 1.1 dB of the performance limit. Finally, we

    consider a CRC and develop a practical multi-level dirty-paper coding strategy using

    LDPC codes for channel coding and trellis-coded quantization for source coding. The

    designed scheme is found to operate within 0.78 dB of the theoretical limit.

    By developing practical coding strategies for several cooperative communication

    channels which exhibit performance close to the information theoretic limits, we show

    that cooperative communications not only provide great benefits in theory, but can

    possibly promise the same benefits when put into practice. Thus, our work can be

    considered a useful and necessary step towards the commercial realization of cooperative

    communications.

publication date

  • August 2010