The Research Of MIMO Based On IEEE802.16M WMAN

Networks and services of the third generation are widely used over the world with the rapid development of mobile communications and the ratio of data service is larger and larger according to the requirement of various services. The traditional voice service is expanded to the broadband data service. Meanwhile, the broadband wireless access is from the local access to the wide area mobile access and the trend to "the mobilization of the broadband access" is obvious. WiMAX which is based on the techniques of OFDMA and MIMO was proposed by IEEE in2004and the project of IEEE802.16m was started soon. The WMAN system based on the protocol of IEEE802.16m is the first mobile communication system based on the techniques of OFDMA and MIMO and its performance can be improved further to fulfill the requirement of telecommunications operators.OFDM and MIMO are used in the WMAN system based on the protocol of IEEE802.16m. The basic idea of OFDM is to divide the serial high speed data stream into parallel low speed data streams which are transmitted in subcarriers to alleviate the multipath effect. With MIMO, the data stream can be transmitted in parallel independent channels to improve the system throughput. This paper mainly researches MIMO in WMAN systems based on the protocol of IEEE802.16m. The main research work and contributions are detailed as follows.1. Modeling the channel is necessary in theoretical researches or engineering analyses and designs. The paper studied the techniques of MIMO channel modeling in IEEE802.16m WMAN and then selected the SCM model for simulations.2. Channel state estimation is the precondition of the correct detection in the receiver. The paper studied algorithms of estimating the downlink channel state in IEEE802.16m WMAN, including LS, MMSE and the method based on DFT. Simulation results revealed their performance. The channel state estimation algorithms based on superimposed pilots and interleaving pilots are presented in the paper and simulation results indicated the effects of the number of pilots.3. Various fading effects are encountered in channels of wireless communication systems and the diversity technique is often used to improve the performance. The paper studied the diversity algorithms of MIMO in IEEE802.16m WMAN, designed a kind of diversity scheme, simulated the perfonnance of diversity algorithms in the scenarios of various array configurations and different speeds.