Advanced Receiver Strategy for Co-Channel Interference in Multibeam Satellite Systems

Abstract

Breaking the barrier of Terabit-per-second connectivity in multibeam satellite systems is impeded by the scarcity of frequency spectrum. Aggressive frequency reuse can overcome spectrum limitations but at the expense of inducing harsh cochannel interference (CCI). This problem is further compounded by memory effects of CCI, arising when co-channel signals combine asynchronously. To avoid exponential increase in complexity, state-of-the-art user-terminal receivers assume memoryless CCI, thus harming their performance. First, we provide analytical characterization of CCI accounting for memory, a formulation that captures synchronization impairments. Then, low-complexity receivers are developed to compensate for spatial and temporal CCI profiles, with computational complexity increasing only linearly in the memory span. This is achieved by our novel soft-in soft-out, iterative divide-and-conquer (IDAC) strategy, decomposing interference into smaller sets depending on intensity. A set is created from weak interferers which are not decoded but considered as thermal noise. The interferers which are decoded are further split into a set that subtracts strong ones and another set addressing intense interferers in an optimal-Bayesian fashion. Extensive numerical studies reveal that the IDAC architecture offers lossless compensation of dominant CCI with memory, when rate coordination is guided by network information theory, offering beam-edge user terminals an edgeless quality-of-service.