Multi-beam satellite MIMO systems: BER Analysis of interference cancellation and scheduling

The return-link of a multi-beam satellite system can be regarded as a multiple-input multiple-output (MIMO) system, with users generating interference to each others. If the number of frequencies in the system (or number of colors) gets low (e.g. down to 1, for full frequency reuse), the level of inter-user interference gets higher, but the bandwidth available to each user is increased. Hence it is not straightforward to understand whether the resulting net system capacity is improved by reducing the number of colors. This paper considers this scenario and some state-of-the-art interference-cancellation techniques, together with a novel proposal, to show the impact of the satellite channel on the uncoded Bit Error Rate (BER). The known results from information theory on the optimal ordering for interference cancellation and on scheduling algorithms are exploited to prove the theoretically expected gains: the BER experienced by the worst user can be reduced and the overall system fairness can be increased (i.e. the difference among the BERs experienced by the users is decreased).