Feedback Requirements for Greedy Interference Avoidance

Greedy interference avoidance provides distributed algorithms for CDMA codeword optimization. These algorithms are based on the implicit assumption that active users have access to the correlation matrix of the the received signal, which should be made available to users through a feedback channel. As a consequence the performance of greedy interference avoidance algorithms will be limited by the accuracy with which the correlation matrix is fed back to the users. In this paper we present two schemes that may be used for correlation matrix feedback in greedy interference avoidance algorithms, and study their effects on the system performance. Numerical examples obtained from simulations are presented to illustrate the performance of the proposed correlation feedback methods.