Two-Timescale Design for AP Mode Selection of Cooperative ISAC Networks

TL;DR

This paper proposes a two-timescale AP mode selection scheme for cooperative bi-static ISAC networks, optimizing sensing and communication performance with low system overhead using advanced optimization techniques.

Contribution

It introduces a novel two-timescale design framework for AP mode selection in cooperative ISAC networks, combining statistical and instantaneous CSI adaptation with efficient optimization methods.

Findings

Closed-form expressions for communication rate and sensing SINR.

The proposed scheme converges quickly and outperforms baseline methods.

Simulation results confirm the effectiveness of the AP mode selection approach.

Abstract

As an emerging technology, cooperative bi-static integrated sensing and communication (ISAC) is promising to achieve high-precision sensing, high-rate communication as well as self-interference (SI) avoidance. This paper investigates the two-timescale design for access point (AP) mode selection to realize the full potential of the cooperative bi-static ISAC network with low system overhead, where the beamforming at the APs is adapted to the rapidly-changing instantaneous channel state information (CSI), while the AP mode is adapted to the slowly-changing statistical CSI. We first apply the minimum mean square error (MMSE) estimator to estimate the channel between the APs and the channels from the APs to the user equipments (UEs). Then we adopt the low-complexity maximum ratio transmission (MRT) beamforming and the maximum ratio combining (MRC) detector, and derive the closed-form expressions of the communication rate and the sensing signal-to-interference-plus-noise-ratio (SINR). We formulate a non-convex integer optimization problem to maximize the minimum sensing SINR under the communication quality of service (QoS) constraints. McCormick envelope relaxation and successive convex approximation (SCA) techniques are applied to solve the challenging non-convex integer optimization problem. Simulation results validate the closed-form expressions and prove the convergence and effectiveness of the proposed AP mode selection scheme.