Partial Channel Information Feedback Scheme For Resource Allocation In OFDM Systems

With the rapid development of mobile communication systems, people require for more rapid data communication rates and higher quality of data service. Orthogonal frequency division multiplexing (OFDM) has the advantages in overcoming frequency selective fading, and different channels are independent and have different fading between each other in OFDM system. Besides, it provides a flexible resource allocation for the degree of freedom. OFDM system combines with Multiple Input Multiple Output multiple (MIMO) technique with spatial diversity gain and become to be MIMO-OFDMA system, which is proved to be acquiring lower bit error rate and higher data rate in wireless communication systems.At first, this thesis describes the OFDMA technology and MIMO-OFDMA technology and lists several key technologies, which are the foundation and contents of this thesis based on.Then, this thesis introduces resource allocation algorithm in multiuser OFDM systems. Compared with the traditional research efforts on OFDMA resource allocation that they are based on the availability of perfect channel state information, this thesis proposes a resource allocation algorithm under non-ideal channel information, to consider the channel estimation error, channel feedback delay. It takes advantage of the time domain, frequency domain, multi-user diversity gain, to maximize system performance. Finally, on the basis of above, we derive that resource allocation algorithm for the practically relevant case of when only a discrete number of modulation and coding levels are available.Resource allocation in OFDMA systems combined with MIMO technology is a hot topic in recent years. But different users in the same spatial multiplexing carrier to introduce co-channel interference, the system's transmission capacity severely reduced. First several typical Zero-forcing beamforming algorithm is listed. On this basis, a threshold-setting scheme is proposed an algorithm in order to reduce feedback overhead, and get its advantage compared with other typical algorithm.