Quasi-optimal grouping for broadcast systems with hierarchical modulation

Recently, the present authors proposed to combine time sharing with hierarchical modulation to increase the transmission rate of broadcast systems. The proposal involves grouping the receivers in pairs in order to transmit with hierarchical modulation. Several grouping strategies were introduced but the optimal matching remained an open question. In this reported work, it is shown that the optimal grouping is the solution of an assignment problem, for which efficient algorithms exist such as the Hungarian method. Based on this algorithm, the performance of the optimal grouping in terms of spectrum efficiency for a digital video broadcasting - satellite - second generation (DVB-S2) system is studied.