Institute of Electrical & Electronic Engineers
Cyclic-Delay Diversity (CDD) based frequency-selective scheduling is an effective technique to increase system capacity with low complexity. By increasing the channels' frequency selectivity with cyclic delays, the merit of multi-user diversity can be exploited more effectively in the system. This paper aims to optimize the design of the CDD-aided frequency-selective scheduling for downlink OFDMA systems. First, a low-complexity search of CD-values is proposed that results in a higher system capacity than the existing methods. Second, a new feedback method is proposed based on the principle of proportional-fair, where users who currently enjoy more downlink source are allotted less uplink resource for feedback.