Contention resolution and channel estimation in satellite random access channels

We consider the random access channel (RACH) of a multi-beam satellite system with universal frequency reuse. We benefit from the spatial diversity and the strong directivity of multiple antennas at the satellite to resolve contentions and perform channel estimation. We propose two approaches to detect active satellite terminals (ST) and estimate the channel coefficients of some or all the colliding STs: Grid Reduction (GR) and Successive Channel Cancelation (SCC) algorithm. The performance of the proposed approaches is assessed by numerical results and compared with the conventional satellite RACH system. Both approaches outperform the conventional RACH with Slotted-ALOHA and SCC algorithm shows better performance than GR approach.