Spatial Group Based Optimal Uplink Power Control for Random Access in Satellite Networks

In this paper, we propose a spatial group based optimal uplink power control scheme to enhance the performance of random access (RA) in satellite networks. In the proposed scheme, satellite machine-type terminals (SMTs) are divided into multiple groups based on their spatial locations in a distributed fashion, and the target received power levels of SMTs are the same in the same group but different from group to group by means of uplink power control, which enables the received power diversity. The received power levels of SMTs in different groups are designed by taking into account their path losses, which effectively reduces the energy consumption of SMTs. The threshold based capture model at the gateway demodulator is adopted, and the packet loss ratio (PLR) based on this model is derived by using density evolution analysis. An optimization problem is formulated and solved to jointly find the optimal number of power levels and the optimal values of power levels, which maximizes the RA system throughput. Simulation results show that the proposed scheme can obtain considerable performance improvement with respect to the conventional schemes in terms of normalized throughput, PLR, and average energy consumption.