Research On The Link Adaptive Technology In High-Speed Wireless Communication Systems

With the growing number of mobile devices and the prevalence of various online mobile applications(e.g.,broadband and multimedia service), mobile users have an increasing demand on the data transmission rate and performance of mobile communication systems. Meanwhile, energy efficiency is becoming a critical issue for mobile communications due to the increasing energy consumption and limited battery capacity. As a result, there is an urgent need for energy-efficient systems that can minimize energy consumption. This raises new challenges in data rate, energy efficiency and QoS requirements for the next generation communication system. Nowadays, the adaptive technology has a more and more important effect on the main qualities of communication network. Thus, the study on the application of adaptive technique should be focused.In this thesis, based on the hardware vertification platform of the Ultra-High-Throughput Wireless LAN System, the adaptive subcarrier, bit and power allocation in high speed wireless communication link and the cross-layer adaptive technology in spectrum sensing link are studied. The specific contents are as follows:Firstly, an introduction was given for the developement of link adaptive technology in OFDM communication systems. Furthermore, the currently used resource adaptive allocation schemes for single and multi-user OFDM system was analyzed, which would provide a good background knowledge for further study of energy-efficient transmission in OFDM system. Secondly, the research is focused on the energy-efficient adaptive subcarrier-bit-power allocation for a downlink muti-user OFDMA network. After providing a definition of energy-efficiency, the computation model of high energy-efficiency was established. In view of the non-linear constraints of this model, an adaptive subcarrier, bit, and power allocation scheme based on genetic algorithm is proposed to optimize energy-efficient transmissions. Moreover, the traditional genetic algorithm was improved with a new elitist method and a penalty handling method that are specific to our optimization problem. The simulation result showed that the proposed scheme can obtain more satisfied solutions in a shorter time, compared to the traditional methods.Finally, we introduced the implementation of cross-layer adaptive technology for the spectrum perception communication link based on the ultra-high-speed WLAN hardware varification platform. A valid spectrum handoff strategy was proposed. The introduction mainly contained the cross-layer adaptive design of spectrum management and the study of cross-layer adaptive technology in MAC-PHY layer.