Adaptive Resource Allocation Algorithm For Distinguishing User Moving Speed In Ofdma-Mimo System

With the coming of the new round of large-scale infrastructure investment, we demand for wireless broadband services in the high-speed mobile environment which is represented by the continuous development of high-speed railway. Wireless communication system in the high-speed mobile environment has attracted more and more attention. Due to the constraints of larger frequency offset, fast channel variation and other factors, the existed wireless resources allocation schemes cannot satisfy the QoS requirements of users when they move fast.When a user moves fast, he/she may experience deep fading in a short time because of the fast channel variation, which will result in the sharp deterioration of BER performance. Therefore, resources allocation needs to consider the QoS requirements of users while the characteristics of the high-speed mobility are taken into account. This thesis focuses on how to allocate radio resource reasonably, in order to optimize system performance on the basis of ensuring the QoS requirements.We firstly introduce the characteristics of high-speed mobile environment and the related technical background. On this basis, the impact to AMC technology due to the fast channel variation is analyzed. Then we introduce the theory of QAM technology, and discusse the relationship between the minimum Euclidean distance of the QAM signal constellation and the BER as well as the energy of the QAM signal. Futhermore, we give the signal preprocessing method of high-speed user and low-speed user. Based on this, we detail the principles of resource allocation for high-speed and low-speed users, which calculates the threshold of minimum Euclidean distance that satisfies the requirements of user BER. After that, based on greedy algorithm, a resources allocation algorithm which distinguishes high-speed and low-speed users is proposed. Finally, we introduce the related simulation parameters of OFDMA-MIMO system and build up system simulation platform. Combined with the characteristic of the two-dimensional time-frequency, we give the simulation and evaluation results. The simulation results show that this algorithm can not only meet the QoS requirements of low-speed users, but also ensure the QoS demand of high-speed users through allocating radio resource reasonably which aims to optimize system performance.