Dynamic Resource Management in CDRT Systems Through Adaptive NOMA

Cooperative nonorthogonal multiple access (NOMA) technology has the potential to greatly extend network coverage and elevate overall system performance. The NOMA-based coordinated direct and relay transmission (CDRT) scheme takes full advantage of successive interference cancellation results to effectively reduce interference from forward signals and improve the efficiency of parallel link transmission. However, the existing literature has overlooked an important premise of the CDRT system: the center user must successfully decode the signal for the edge user. In this work, new adaptive transmission schemes are proposed to enhance the performance of NOMA-based CDRT systems. Specifically, dynamic power allocation and maximum ratio transmission schemes are utilized to improve the transmission quality of the first hop, and directional antenna technology is utilized to enhance the transmission quality of the second hop. The closed-form expressions for the exact effective sum throughput are derived. Finally, simulation results are presented to validate the correctness of the theoretical analysis and these results demonstrate the effectiveness of the proposed scheme when compared to benchmark schemes.