Rateless coding over wireless channels: Theory, design and applications

Abstract

In this work we investigate rateless coding and modulation for wireless communication systems. In particular we are interested in channels in which only the transmitter has channel knowledge. For this setting, we show that rateless codes have properties that make them well suited for wireless systems. We advance the theory of rateless codes by proving the existence of rateless codes which are "good" for all possible realizations of fading channels simultaneously. To complement rateless coding, we introduce a novel modulation scheme called mu-PAM modulation. We show that typical M-ary modulation schemes are not always well suited for the channels considered in this work, and that mu-PAM modulation has benefits relative to standard M-ary PAM. A simple demodulation scheme is presented and its performance is analyzed and simulated. Applications using rateless codes over wireless channels are considered. We examine the behavior of a streaming application with delay constraints over fading channels, comparing rateless codes with other traditional systems. Benefits of the rateless approach are presented, and theoretical guarantees on probability of outage are developed. Finally, the use of rateless codes for relay networks are explored and we demonstrate theoretic limits on the rate of communication for the proposed relaying strategy. Simulations validate the performance of the strategy.