Complexity Comparison of MIMO Channel Modelling Methods

Computational complexity of simulation of channel models has become an important issue due to the increased requirements for, e.g., bandwidth, number of antennas, quality of service (QoS), number of users, and advanced network topologies. This paper compares the computational complexity of generation of multiple-input multiple-output (MIMO) radio channel realizations with different modelling principles, namely correlation matrix based and sum of rays based methods. Three different aspects are compared. They are complexity of channel coefficient generation, number of required parameters, and the complexity of simulation. The comparison shows that the complexity of the channel coefficient generation is in about the same order of magnitude when the number of MIMO antenna pairs is up to 16 (e.g. 4times4 MIMO). When the number of antennas is higher, the correlation matrix method has higher complexity. The complexity of correlation method depends strongly on the number of antennas while the sum-of-rays method is quite insensitive to it. The simulation complexity dominates the overall complexity and is the same for both methods. The main conclusion of this paper is that the sum-of-rays based method is recommendable especially when the number of antenna pairs is high.