Coding for Sensing: An Improved Scheme for Integrated Sensing and Communication over MACs

A memoryless state-dependent multiple-access channel (MAC) is considered, where two transmitters wish to convey messages to a single receiver while simultaneously sensing (estimating) the respective states via generalized feedbacks. This scenario is motivated by joint radar and communication, which aims to co-design radar sensing and communication over shared spectrum and hardware. An improved inner bound is provided on the fundamental rate-distortions tradeoff which characterizes the communication rates the transmitters can achieve while simultaneously ensuring that their state-estimates satisfy desired distortion criteria. The new inner bound is based on a scheme where each transmitter codes over the generalized feedback so as to improve the state estimation at the other transmitter. We demonstrate the advantage of the proposed scheme other than previous ones through some examples. This is in contrast to the previously proposed schemes where coding is only used to convey data but not sensing information.