| With the increasing requirements in wireless communication services, more and more researchers concentrate on how to get good use of limited wireless resource. Wireless link adaptation technology, because of its high spectral efficiency, is becoming one of the key technologies in wireless communication system. The goal of wireless link adaptation technology is to achieve the best performance of communication by changing the parameters of transmitter and receiver according to the variation of the mobile channel dynamically, such as transmit power, modulation scheme and coding rate.Communicated with multi-antenna both at the transmitter and receiver, Multiple Input Multiple Output (MIMO) could enlarge the channel capacity dramatically. Vertical Bell Laboratories Layered Space-Time (V-BLAST) is a space-time processing architecture which is getting more and more attention for its simplified structure. To achieve the best performance, wireless link adaptation technology, including bit and power loading, is applied in V-BLAST in this treatise.In the third chapter, we investigated and simulated the application of signal detection algorithms in V-BLAST and found an effective transmit power allocation scheme to improve the performance of V-BLAST system. From the simulation results, we can see that the performance of V-BLAST system can be improved more than 2dB if power allocation is applied at the transmitter.In the fourth chapter, we presented the MMSE Soft Interference Cancellation detector as the signal detector, and proposed an effective transmit power allocation scheme to improve the performance of MIMO-OFDM system. If LDPC channel coding is applied, we can find the performance can be improved about 1dB when BER is 10-6.By precoding we mean all methods applied at the transmitter that facilitate detection at the receiver. At first, we investigate the application of precoding in the MIMO system and put emphasis on the discussion of Tomlinson-Harashima... |
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