telecommunications equipment developers

Abstract: In this paper, we focus on investigating the resource allocation in an integrated sensing and communication (ISAC) system assisted by a simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS). Due to the coupled non-convex nature of the optimization problem, solving the above joint resource optimization problem while guaranteeing superior sensing performance is challenging, especially in dynamic environment. To conquer such challenge, prior iterative optimization algorithms have been presented. However, practical implementations of these prior algorithms face notable computational challenges, e.g., the reliance on accurate global channel information and the assumption of ideal phase shifts. In this context, we propose a model-driven deep learning framework for jointly optimizing the transmit beamforming and waveform in ISAC networks with low-overhead. In addition, we adopt the Cramer-Rao lower bound (CRLB) as the sensing performance metric, and the multi-user interference (MUI) energy as the communication performance metric for performance evaluation. Besides, our framework jointly optimizes the transmit beamforming, waveform and the STAR-RIS reflection/transmission coefficient matrices by minimizing the weighted sum of MUI energy and CRLB. Our study also considers the impact of imperfect channel information, making the research scenario more aligned with real-world applications. Simulation results validate that the proposed framework not only achieves higher sum-rate performance comparable to traditional iterative algorithms but also significantly reduces computational complexity in terms of algorithm execution time, as well as exhibits inherent robustness.

Abstract: Random access (RA) is one of the most foundational medium access control (MAC) layer scheduling schemes for handling unpredictable data traffic from multiple terminals. While multi-agent reinforcement learning (MARL) has been explored to optimize RA-based wireless networks, its reliance on experience-driven, distributed policy learning incurs significant training overhead for each optimization task, limiting its feasibility in real-world applications. In this work, we propose to leverage a foundation model (FM) to improve MARL efficiency across diverse RA network optimization tasks. Specifically, we design an FM-aided actor-critic algorithm within a consensus-based decentralized MARL architecture and provide its convergence analysis under local reward exchanges and nonlinear value function approximations to show that our algorithm achieves the same convergence order as the conventional MARL with critic model exchanges and linear approximations. Our numerical results show that our FM-based approach significantly enhances MARL speed for RA network optimization.

Abstract: Disaggregated mobile networks expose open interfaces for independent agents to control the Radio Access Network (RAN). The interactions between agents with contrasting objectives can result in conflicts. However, existing conflict mitigation methods treat agents that control the same parameter as being in a conflict that requires arbitration of their actions, without assessing whether their objectives can be satisfied simultaneously. In this paper, we introduce a control-theoretic approach to determine when agents can coexist and share control of the same parameters. We model threshold-based agents often encountered in the literature as sampled deadband feedback controllers and represent their objectives through Key Performance Indicator (KPI) targets and tolerances that define acceptable deadband bounds. We derive compatibility conditions from these bounds and show that compatibility for any number of agents and monitored KPIs can be established through pairwise tests. We propose a conflict mitigation policy that allows compatible agents to share control of the same network parameters while restricting arbitration to cases where their objectives cannot be satisfied simultaneously. We evaluate our policy through simulations using NIST's ns3-oran extension of ns-3, and our results show that it enables agents to share control with near-zero Service Level Agreement (SLA) drift when their objectives are compatible and the shared acceptable range is attainable, while matching Priority Mitigation when their objectives are incompatible.

Abstract: The incorporation of non-orthogonal multiple access (NOMA) and reconfigurable intelligent surface (RIS) provides a new solution to improve spectral efficiency. Unfortunately, the channel estimation error of RIS is noteworthy due to the absent active radio frequency link. Meanwhile, the transceivers at base stations (BS) and users also exist hardware impairments (HWI). The imperfect channel state information (CSI) and HWI will degrade the communication performance such as outage probability or data rate. To alleviate such performance deterioration, we propose a robust design scheme to minimize the BS transmit power when the target rate of users is satisfied in RIS-assisted single-beam and multi-beam NOMA networks with transceiver HWI and imperfect CSI. Further, the perfect successive interference cancellation (SIC) condition in single-beam and multi-beam NOMA networks is investigated, and the optimization problem is proposed based on perfect SIC conditions. To tackle the non-convex problem, we provide an effective algorithm combining Bernstein-type inequality and semi-definite relaxation. Numerical results demonstrate that the proposed scheme outperforms non-robust RIS-assisted NOMA scheme that ignores HWI and imperfect CSI. Moreover, the multi-beam NOMA network obtains higher beam gain compared to the single-beam NOMA network, and thus there is a superior performance in multi-beam NOMA networks.