Fundamental Limits of Bistatic Integrated Sensing and Communications over Memoryless Relay Channels

TL;DR

This paper explores the fundamental limits of combined sensing and communication over relay channels, deriving bounds and proposing a coding scheme to optimize the tradeoff between data transmission and parameter estimation.

Contribution

It introduces a capacity-distortion framework for bistatic sensing and communication, extending bounds and proposing a hybrid coding scheme for relay channels.

Findings

The hybrid scheme achieves optimal sensing when communication is ignored.

Upper and lower bounds coincide for specific relay channel classes.

Numerical results illustrate the tradeoff and benefits of integrated design.

Abstract

The problem of bistatic integrated sensing and communications over memoryless relay channels is considered, where destination concurrently decodes the message sent by the source and estimates unknown parameters from received signals with the help of a relay. A state-dependent discrete memoryless relay channel is considered to model this setup, and the fundamental limits of the communication-sensing performance tradeoff are characterized by the capacity-distortion function. An upper bound on the capacity-distortion function is derived, extending the cut-set bound results to address the sensing operation at the destination. A hybrid-partial-decode-and-compress-forward coding scheme is also proposed to facilitate source-relay cooperation for both message transmission and sensing, establishing a lower bound on the capacity-distortion function. It is found that the hybrid-partial-decode-and-compress-forward scheme achieves optimal sensing performance when the communication task is ignored. Furthermore, the upper and lower bounds are shown to coincide for three specific classes of relay channels. Numerical examples are provided to illustrate the communication-sensing tradeoff and demonstrate the benefits of integrated design.