A gradient-based ordering for MIMO decoding

The ordering of the columns of the channel matrix has a deep impact in the performance of many decoding methods for MIMO problems. The most popular algorithms for computation of good orderings use as only input the channel matrix (such as the V-BLAST ordering). However, there are other interesting algorithms that compute the ordering as a function of the matrix and of the signal to be decoded. Here we propose a new gradient-based scheme to obtain a good ordering that uses as input the channel matrix and the signal to be decoded. In this paper, this new ordering method is compared experimentally with other algorithms, showing that it is an interesting method, specially in connection with maximum likelihood decoding algorithms such as sphere decoding algorithms.