On the Optimum Packet Power Distribution for Spread Aloha Packet Detectors With Iterative Successive Interference Cancelation

Recent work has been stimulated by the need to enhance the satellite networks´ Random Access (RA) performance. Results have shown that large performance improvement is possible by exploiting Iterative Successive Interference Cancelation (I-SIC) at the demodulator side. Coded spread spectrum Aloha (SSA) is a particularly suitable access technique for RA satellite networks due to its inherent asynchronous access nature and its high multiple access Achievable Sum Rate (ASR). Moreover, the adoption of I-SIC allows further boosting of the SSA sum rate and its robustness to the packet power unbalance. In this paper, we derive an analytical approach to the optimal packet power distribution that maximizes the performance of SSA RA exploiting I-SIC at the demodulator. The proposed approach takes into account the physical layer coding and modulation together with the number of demodulator iterations and the non-ideal cancelation effects. The analytical findings are successfully compared with the simulation and measurement results. Finally, a practical algorithm that approximates the optimum incoming power packet distribution in a realistic multi-beam satellite broadband network with open-loop power control is proposed and validated in a study case.