Block-fading Channels

Collaborative techniques have been proposed to improve communications in the presence of a hostile jammer. A distributed detection and decoding technique based on collaborative decoding has been shown to be effective for communications over non-fading channels for coherent communications. In this paper, we consider collaborative communications strategies for jamming channels in which the message and jamming signals experience independent block fading at each receiving node. Furthermore, we assume that the phase of the message signal is not known and must be estimated from the received signal. Joint decoding and estimation of all of the fading and jamming parameters is computationally prohibitive, so we develop iterative estimation and decoding algorithms. The fading coefficient and parameters of the jamming signal are estimated using the EM and BCJR algorithms. The results show that the proposed technique is an effective response to hostile jamming.