Research On Adaptive Modulation And Coding In V-BLAST

With the rapid development of the wireless communication systems(especially the mobile communication systems), frequency resource is becoming scare. In recent years, Multiple Input Multiple Output (MIMO) system has become an important scheme that could increase the spectral efficiency. And, V-BLAST techniques are one of the key schemes for achieving high data rate and performance in 3G and 4G mobile communications.V-BLAST is a kind of technique of space diversity. It uses more than one antenna in the transmitter and receiver to send and receive signals. So, the scheme can utilize the characteristic of multi-path fading in wireless channel to increase the spectral efficiency. In this paper, we introduce the basic scheme of V-BLAST system and several main detection algorithms of V-BLAST system.Adaptive transmission is a technique which could increase transmission quality and rate efficiently. And in the Adaptive transmission system, Adaptive Modulation(AM) and Adaptive Modulation and Coding(AMC) are two techniques that interest people a lot. The main idea of AMC is that high modulation order and low coding rate can be used to boost up the average spectral efficiency when the channel state is good, and low modulation order and high coding rate can be used to increase the error protection when the channel state is bad. The adaptive algorithm in this paperUntil now, there is no document research especially on AM and AMC algorithm in V-BLAST system. So in this paper, we first add AM technique into a V-BLAST system. With the constraint of bit error rate(BER), choose different order of modulation depend on the threshold. Then we add adaptive coding to implement AMC in V-BLAST system. The adaptive algorithm in this paper is depend on thresholds. The simulation results show that the BER(AM) or FER(AMC) and spectral efficiency can achieve higher performance compared with fixed modulation and fixed modulation and coding.