Abstract:

A multiple-input multiple-output fixed-complexity sphere decoder (FSD) with low-complexity channel matrix ordering is proposed based on reliabilities of the minimum mean square error (MMSE) decoder's decision variables. The proposed ordering algorithm first performs MMSE decoding, computes the reliabilities of MMSE decoder's decision variables, and finally orders channel matrix based on the reliabilities. The algorithm not only effectively reduces the complexity of FSD in preprocessing stage, but also overcomes its sequential nature, more suitable for applications. Simulation result shows that the performance loss caused by the low-complexity ordering algorithm is negligible and quasi-maximum likelihood performance can be achieved.

Key words: multi-input multi-output, sphere decoding, fixed-complexity sphere decoding