Interference Avoidance Algorithms

Summary

We have presented four different distributed interference avoidance algorithms, all of which are guaranteed to converge in GSC and/or sum capacity. We have shown that absolutely maximizing sum capacity also absolutely minimizes GSC if the eigenvalues of the covariance R are only constrained by their sum - which hints that sum capacity maximization and GSC minimization might be equivalent optimizations. However, we have not yet shown codeword convergence and more importantly, we have not shown convergence to optimal values of GSC and sum capacity. In fact, we have not even determined the optimal values of these quantities in general, but are in effect simply taking on faith that greedily improving performance, one codeword at a time, is a useful thing to do. As one might expect, it turns out that such greedy and uncoordinated but asynchronous behavior is indeed a good thing to do as we shall see as we carefully explore these issues in chapter 3.