Abstract:This paper proposes an downlink cross-layer design procedure and algorithm for On-board switch scheme based on OFDM. The ultimate objective is to maximize the system downlink throughput subject to spot beam downlink transmit power constraint, downlink channel state information about each user, bit error ratio requirement of subcarrier after signal detection by users, and destination user and QoS of each service. The algorithm can adaptively allocate subcarriers and chose modulation scheme for every subcarrier among different users and services. Simulation results show that the proposed algorithm is able to guarantee consistent degree of QoS for the same service.