Multi-user Ofdm And Mimo-ofdm System Resource Allocation

Dynamic resource allocation for multi-user Orthogonal Frequency Division Multiplexing (OFDM) systems and multi-user Multiple-Input Multiple-Out-put (MIMO)-OFDM systems is the key technique in next generation mobile communication. It is an important guarantee to improve system capacity and satisfy user's Quality of Service (QoS). Main work for this issue was introduced as follows:Firstly, with typical resource allocation optimization model, capacity performance of power average allocation and water-filling allocation for OFDM system were simulated and compared. Since quantization error would be cumulated while solving the discrete issue by water-filling algorithm. The optimal solution was hard to get. When discrete and multi-dimensional optimization issues for multi-user radio resource allocation were solved, complexity is high. In order to improve radio resource utilized efficiency and allocation accuracy, on the condition of total transmitted power limited and subscriber's QoS satisfied, capacity was demonstrated as count of access user. It is the optimal target to maximize access subscribers. Greedy algorithm of discrete optimal method was used to get the optimal solution. Since the optimal solution of multi-user radio resource allocation couldn't be confirmed to find without heuristic function. So user priority was used as heuristic function of greedy algorithm to transfer the multi-user radio resource allocation issue to several single users'issues. The target of dimension reduce was got. The simulated result indicated that comparing the classic greedy algorithm, the number of accessed users was increased by improved algorithm. Less power was consumed while accessing the same number of users. System power could be utilized with high efficiency.After having the above conclusion, resource allocation for multi-user MIMO-OFDM systems was further studied. With optimization model of system's capacity maximization, greedy algorithm and heuristic function for multi-user OFDM systems were extended to multi-user MIMO-OFDM systems. The limited condition in user dimension was relaxed by user priority. Optimal process was simplified by sorting channel state information. The complexity of optimal issue was reduced, but some subscriber's data rate is bad. In order to improve subscriber's data rate, in view of subscriber's fairness, proportional compensation power allocation was proposed. Simulation result certified that good data rate performance was gained by all access users with proposed method. The more antennas and subcarriers, the better the data rate performance.The model, method and conclusion in this paper provided good reference for multi-user radio resource management in next generation mobile communication systems.