Abstract: In view of the problem that the satellite-ground link resource allocation is not flexible， and the effective QoS(quality of service) guarantee mechanism is lacking， a cross layer resource allocation algorithm for constellation communication system is proposed on the basis of QoS. By using adaptive encoding modulation (ACM) technology， and defining user channel quality assessment algorithm， adjustable fairness scheduling algorithm， QoS business classification scheduling algorithm and user service allocation weight function， the terminal user can be specified physical layer parameters such as working frequency， time slot， coding mode， modulation mode， and etc. The allocation of physical layer channel resources could be realized flexibly according to the QoS security requirements， and the balance could be reached between enhancing the system utilization rate and meeting the QoS security requirements. The simulation results show that the proposed algorithm can achieve the reasonable scheduling of satellite-ground link resources based on the business QoS and user channel quality.

Key words: constellation communication system, QoS(quality of service), channel quality assessment, resource allocation, adjustable fairness algorithm