This paper investigates the problem of joint subcarrier and power allocation in the coexistence of radar and multi-user communication systems. Specifically, in our research scenario, the base station (BS) provides information transmission services for multiple users while ensuring that its interference to a separate radar system will not affect the radar's normal function. To this end, we propose a subcarrier and power allocation scheme based on orthogonal frequency division multiple access (OFDM). The original problem consisting involving multivariate fractional programming and binary variables is highly non-convex. Due to its complexity, we relax the binary constraint by introducing a penalty term, provided that the optimal solution is not affected. Then, by integrating multiple power variables into one matrix, the original problem is reformulated as a multi-ratio fractional programming (FP) problem, and finally a quadratic transform is employed to make the non-convex problem a sequence of convex problems. The numerical results indicate the performance trade-off between the multi-user communication system and the radar system, and notably that the performance of the communication system is not improved with power increase in the presence of radar interference beyond a certain threshold. This provides a useful insight for the energy-efficient design of the system.

翻译：本文研究了雷达与多用户通信系统共存场景下的子载波与功率联合分配问题。具体而言，在本研究场景中，基站（BS）在为多个用户提供信息传输服务的同时，需确保其对独立雷达系统的干扰不影响雷达正常功能。为此，我们提出一种基于正交频分多址（OFDM）的子载波与功率分配方案。原始问题涉及多元分式规划与二进制变量，具有高度非凸性。由于问题复杂度较高，我们在不改变最优解的前提下引入惩罚项对二进制约束进行松弛处理，随后将多个功率变量整合为矩阵形式，将原始问题重构为多比分式规划（FP）问题，最终采用二次变换将非凸问题转化为一系列凸优化问题。数值结果表明，多用户通信系统与雷达系统之间存在性能权衡关系，特别值得注意的是，当雷达干扰超过某一阈值时，单纯增加通信功率并不能提升通信系统性能。这一发现为系统的能效优化设计提供了重要启示。