Abstract
We focus on the angle of departure and angle of arrival searching problem for millimeter wave MIMO channel in the thesis. The path loss is high in the mmWave band. Hence, we need to use the massive MIMO and do the beamforming to combat these drawbacks. To implement the beamforming, we have to get the complete channel information. But the channel information is difficult to achieve in mmWave channel. However, the path which can arrive the receiver is few. Hence, there are literature proposed the new channel estimation method to find these paths, and it is called beam search. The most common method is exhaustive search, it trains over all possible beam directions for both the transmitter and the receiver, and find the best beam pair which have maximum signal magnitude. However, the method takes much time to do the beam search, and it also has high complexity. Hence, there are literature also proposed the adaptive algorithm with bisection method to shorten the searching time. In this thesis, we propose a new beam search method which is called balance puzzle beam search method by using the concept of logical puzzle. We design the different algorithm for the single-path and multi-path case and design the optimal threshold to make the spectral efficiency better. Finally, we consider the number of stages as a criterion for judging complexity, and do the complexity analysis. Simulation result show that the balance puzzle beam search method can reduce the complexity and have the comparable spectral efficiency compared to the bisection method, and the cost is to feedback one more bit in each stage.