Optimized Uplink Spectrum Access With Adaptive Interference-Aware User Admission

This letter proposes a novel uplink multiple access scheme that accommodates up toKlow data-rate non-priority users (NPUs) within a selected priority user’s (PU) spectrum, without compromising the PU performance. The uplink base station decodes the PU symbol first, followed by the symbols ofKNPUs, employing successive interference cancellation. A dynamic interference threshold limit, set after PU selection, determinesKand NPU powers in closed-form using a novel instantaneous power allocation scheme (IPAS) inspired by underlay cognitive radio. Spectrum utilization is maximized with precise control over NPU target rate andK. Closed-form throughput analysis, validated via simulations, demonstrates superiority of the suggested scheme over a traditional multiple access employing static optimal power allocation.