Orthogonal Multiple Access with Correlated Sources: Feasible Region and Pragmatic Schemes

In this paper, we consider orthogonal multiple access coded schemes with correlated sources. The sources are distributedly encoded and their correlation is exploited at the access point (AP). In particular, we assume that each source uses a classical channel code to transmit, through an additive white Gaussian noise (AWGN) channel, its information to the AP. Here component decoders, associated with the source encoders, iteratively exchange soft information by taking into account the source correlation. The key goal of this paper is to investigate the ultimate achievable performance limits in terms of a multidimensional feasible region in the space of channel parameters, deriving insights on the impact of the number of sources. In order to analyze the performance of given coded schemes, we propose an extrinsic information transfer (EXIT)-based approach, which allows to determine the corresponding multi-dimensional feasible regions. On the basis of the proposed analytical framework, the performance of pragmatic schemes, based on serially concatenated convolutional codes (SCCCs) and low-density parity-check (LDPC) codes, is discussed. Index Terms Correlated sources, orthogonal multiple access, joint channel decoding (JCD), noisy Slepian-Wolf problem, EXIT chart. This paper was presented in part at the Information Theory and Applications Workshop (ITA’09), UCSD, San Diego, CA, USA, February 2009, and at the Information Theory and Applications Workshop (ITA’10), UCSD, San Diego, CA, USA, February 2010.