Based On Cross-layer Design Of MIMO Wireless Communication Systems

The modern wireless communication technology continues to improve, the reliability of the wireless channel and the effectiveness of the system is also in constant improvement. But wireless communication has some inherent drawbacks, such as the user demand continuing to increase broadband resources, randomness of channel in wireless systems, the spectrum efficiency of communication system due to multipath interference gradually fading, etc, hindering the raising system capacity and improvement of spectrum resource utilization. And it is urging researchers to develop new technologies and scientific research projects to solve these problems.Diversity in multiple input multiple output(MIMO)techniques is in the system of the terminal with a plurality of antenna signals, obtaining diversity gain, making system reliability improved significantly, transmission rate and system capacity also received promoting. But it does not increase the use of the additional bandwidth, arousing extensive interest of researchers. However, the correlation between antenna and physical constraints has increased the difficulty of the existing system to achieve the effect of multiple antennas. Therefore cooperative diversity technology is proposed by researchers. The technology is mainly considered the end user, putting them as a multi antenna system into cooperative transmission, improving the reliability and effectiveness of the system, obtaining the multiplexing gain and diversity gain. In the traditional cable communication system, the hierarchical design has neglected the situation of the system optimization. While cross layer design need to consider the connection between the layers. Breaking the layers’ limits, using the correlation between protocol layers, the coordinating the configuration of each layer, combining the protocol layers to transfer system status information. It makes the optimization of the system to achieve the maximum, but also to ensure the system’s wireless resource utilization and quality of service(QoS)requirements.After a rigorous theory’s analysis combined with the proposed the problem’s solutions, people designed the multi antenna terminal cooperative MIMO wireless communication system model by using the hybrid automatic retransmission request(HARQ)of data link layer and the adaptive modulation coding(AMC)technique of physical layer in cross layer design to improve the system performance. The experimental simulation of the design model proved the multi antenna cooperative communication system of cross layer design effectively improve the throughput performance of wireless communication systems in the premise of meeting the system error rate. Simultaneously it validated that the cooperative diversity technology reduced the packet error rate of the wireless communication system, compared with the non cooperative wireless communication system. For wireless communication system in practice can only provide the problems of tatistical significance QoS guarantee. People analysed the transmission service process of physical layer and the grouping queuing process of link layer to obtain the packet delay QoS combined effect of MIMO system by using the theory of effective bandwidth and effective capacity, proving the expression of packet delay QoS breaching probability. Based on this formula, the researcher proposed a cross layer design of the maximum system effective throughput in MIMO system, meeting the condition of business delay QoS. Simulation results show that the cross layer design can significantly improve the system performance when the noise-signal ratio of the system is relatively low.