A multistage linear receiver approach for MMSE detection in massive MIMO

A key property of a Large-scale MIMO, also known as "massive MIMO" is the orthogonality among channels when the number of antennas at the base station becomes large. Utilizing this property, when using MMSE detection method, instead of dealing with the true matrix inversion operation, which has a cubic computation complexity, it has been suggested that we can simply approximate the matrix inverse by the inversion of its diagonal elements. However, we show in this paper that this naive or diagonal inversion will not perform well under some certain circumstances even if there are hundreds of base station antennas. Motivated by these two facts, we make a tradeoff between detection accuracy and computation complexity and propose a low-complexity detector based on Multistage Linear Receiver. Using the optimized coefficient at each stage, we show that this kind of detector performs well even with low number of stages and accounts for lower computation complexity.