High performance scheduling methods and apparatus for leveraging diversity in relay-enabled wireless networks

摘要

Apparatus and methods are described for scheduling transmission resources in a relay-enabled orthogonal frequency-division multiple access (OFDMA) wireless communications system. Schedulers are described which address the problem of determining the optimal transmission schedule across two hops in the presence of finite user buffers with methods that provide approximate solutions with worst-case performance guarantees and average-case performance that is close to the optimal. The solutions formulate the diversity scheduling problem as an integer program. The weights used in the formulation incorporate the various diversity gains. The integer program is relaxed to a linear program and solved. The resulting fractional solutions are then rounded to integral values. In the process, if buffer or channel feasibility is violated, such violations are addressed through appropriate mechanisms that provide performance guarantees. The relay hop fractional variables are rounded to integral values first. Then the access hop flow is updated based on the rounded relay hop flow. Finally, the access hop variables are rounded to integral values to provide the resulting flow schedule.