Novel partial feedback schemes and their evaluation in an OFDMA system with CDF based scheduling

In an Orthogonal Frequency Division Multiple Access (OFDMA) system, cumulative distribution function (CDF) based scheduling can be applied to prioritize users. In such a wideband multiuser system, it is essential to reduce the typically very large feedback requirement. Herein, we consider a system in which several adjacent highly correlated subcarriers are grouped into a resource block. Then, the formed resource blocks can be further combined to form sub-bands, each consisting of a certain number of resource blocks. To reduce feedback, three feedback schemes, which include two new schemes, are considered and compared. They are a novel CDF based opportunistic scheme, the best M feedback scheme and a hybrid scheme. We provide analytical results which are used to optimally set feedback parameters to best exploit system resource while still maintaining fairness among users. In addition, the convergence behaviors of the total feedback requirement of the schemes are also provided. Simulation are conducted to verify the tradeoff between feedback reduction and system performance. The experiments also show the optimal hybrid and opportunistic schemes are identical and result in the least feedback requirement.