Abstract
Channel estimation problems in theoretical as well as applied statistics have long been of great research interest given their importance in MIMO-OFDM systems based on IEEE802.16e, DOA estimation plays an major role in the channel estimation. In this paper, we discuss principles of MMO-OFDM channel models, summarize classical DOA estimation algorithms, analyze their advantages and disadvantages, then propose some theoretical solutions to the exceptions of these algorithms and our assumptions. Finally, focus on the up-to-date hot spots of DOA estimation technology.