Adaptive Resource Allocation for Satellite Illumination Pattern Design

To ensure quality of service to the users within the coverage area, time-flexible satellite system needs to design a beam illumination strategy, i.e. a time-space transmission pattern that is periodically repeated. The beam activation dwells just long enough to satisfy the traffic demand. The beam illumination pattern design is typically a combinatorial problem with a non-convex structure due to the presence of inter-beam interference. The computational complexity of existing solutions addressing this problem are unbearable for practical systems. In this paper, we propose a low-complexity beam illumination design which splits the task into two sequential sub-problems: (i) Estimation of number of time-slots to be allocated to each geographical area in order to satisfy its demand; (ii) Assignment of illumination slots over the time domain. Note that the outcome of step (ii) determines the resulting interference environment and, as a consequence, the resulting offered capacity. The latter is, at the same time, an input needed for step (i). For this reason, we propose an adaptive system where the two steps are iteratively executed until convergence. Furthermore, we show that a random assignment for step (ii) significantly reduces the complexity without a major impact on the performance. The proposed design is validated and compared with existing schemes using numerical results.