A low complexity parallelizable detector for modular MIMO receivers

In Multiple Input Multiple Output (MIMO) communication system parallel detection is advantageous since it is faster than sequential detection, it does not require power ordering at the receiver and it reduces the system latency. Previous work has proposed a parallel detector (PD) based on successive symbols approximations. The parallel detectors found in literature suffer from high computation complexity. So, in the first part of this paper we propose a Modified Parallel Detection (MPD) algorithm that reduces considerably the system computation complexity. The proposed algorithm can be realized using a parallel modular architecture, which consists on a set of elementary sub-detectors. The MPD also allows performance improvements when it is used as a refinement to the sequential Vertical Bell Labs Layered Space-Time (V-BLAST). However, both PD and MPD algorithms do not generally perform as well as sequential V-BLAST. Thus, In the second part of this paper, we suggest another parallel detection architecture. This later is based on a Minimum Mean Square Error (MMSE) criteria in its first stage and on weighed parallel interference cancellation in its second stage. Simulation results show that our parallel detector performs better than sequential V-BLAST for the same order of complexity.