Research On Multi-antenna In Multi-user Detection System

In recent years, multi-antenna is a key technology of wireless communication system. Multi-antenna can suppress multi-user interference and increase the capacity of communication system. Multi-antenna as known as smart antenna. The core of multi-antenna is adaptive beamforming algorithm. As to receive multi-user, the inter-user interference is one of the main factors that affect system performance. However, the adaptive beamforming algorithm is according to angles of different users to form the beam, make the main beam to aim at the angle of desired user. So that, those undesired signals are suppressed. It can strengthen the desired user's signal, improve system's performance, and maximize the signal-to-interference noise ratio (SINR).First, describe the basic concept of multi-user detection, and introduce the basic theory, structure, classification and technological superiority of multi-antenna. And then analysis adaptive beamforming algorithms, such as Least Mean Square algorithm, Recursive Least Square algorithm, Minimum Variance Distrortionless Response algorithm. After that, conduct a study of multi-antenna combine the multi-user detection system. Use the improved MVDR algorithm to the multi-antenna. It can work out the user's weight to receive different users. Simulate the system bit error rate and SINR in different situations. Simulate the multi-user interference based on multi-antenna. Analysis the system performance from the results of simulation. It proves that, it can suppress the multi-user interference, improve the system performance. Use the RAKE receiver to get users signal from different angles, the simulation shows that use RAKE receiver can improve the receive signal-to-noise ratio and reduce the error rate.