Opportunistic Feedback in Clustered OFDM Systems


Taiwen Tang, Robert W. Heath, Jr., Sunghyun Cho and Sangboh Yun


Proc. of the International Symposium on Wireless personal Multimedia Communications, San Diego, CA, Sept. 17-20, 2006.


This paper proposes a random access based feedback protocol for the clustered orthogonal frequency division multiplexing (OFDM) downlink, which allows users to feed back their channel information to the base station (BS) in a distributed fashion. The proposed protocol employs a contention channel that consists of fixed amount of system resource to carry the feedback for each cluster. Active users send a feedback message with some probability if their average channel quality on one cluster is above a threshold. The threshold and feedback probability are jointly adjusted to maximize a tight upper bound to the average sum rate of all users. The main advantage of this protocol is that it achieves multiuser diversity with only a small amount of feedback overhead.

This paper is available as a IEEE Xplore .