On Quantizer Design for Soft Values in the Multiple-Access Relay Channel

A network with two sources, one relay, and one destination is considered. Under the assumption of noisy source- relay links causing the relay to be unable to decode without error, we propose a quantizer design framework where the quantizer jointly compresses the soft information available for both sources at the relay. The quantizer design is based on the information bottleneck method using the notion of relevant information as an optimization criterion.