Feedback reduction scheme for downlink multiuser diversity

A group random access-based feedback scheme is proposed for multiuser diversity systems, where users are divided into several feedback groups according to their measured channel states. Different random access probabilities and number of feedback minislots are assigned to each feedback group. Each user competes to send a feedback message through random access if its scheduling metric exceeds a threshold. The base station jointly controls the random access probabilities, the thresholds, and the number of feedback minislots to adjust the feedback load. The proposed feedback scheme shows a good system capacity with limited feedback resources regardless of the number of users.