Research And Implemrntation Of Adaptive Link In Mobile Communication Systems

In wireless communication networks, the demand for high data rates and mobility is growing at a rapid pace. However, the performance of wireless links is severely degraded due to channel noise and fading. To enhance throughput in future wireless communication systems, link adaptation has been studied extensively to battle the time-varying channel conditions.Two familiar link adaptation schemes, adaptive modulation and coding(AMC) and automatic repeat request(ARQ), are investigated in this paper. Then we study the impact of the length of the link layer frames on the performance of a wireless link. A cross-layer design is presented to enhance the throughput performance of wireless communication systems. The scheme combines AMC and adaptive frame length control with ARQ. During system running, the transmission mode and frame length are not fixed, but matched to the channel states. If an error packet is detected by the receiver, the transmitter will be ask to transmit the packet again. Analysis and simulation results show that the wireless link throughput can be enhanced by properly choosing AMC transmission mode and ARQ frame length.Future Technology for Universal Radio Environment(FuTURE) research project is an important communication topic of China 863 HighTech Project. The purpose is to follow the development of the wireless communications, and research the air interface technologies of B3G or 4G communication systems. Demo systems are expected to be established so that some key technologies can be verified. Here the GMC-TDD-xDMA demo system which is developed by SEU is presented. Detail descriptions of the link structure are given.