Adaptive Channel Allocation to Increase Capacity Based on Rate Proportional Constraint in the OFDMA System

Demands for mobile communications are drastically increasing. Nonetheless, these demands cannot be fulfilled because of the limited frequency resources available for mobile communications. More specifically, channel allocation for different uses of frequency resource has emerged a critical issue.  This paper presents an adaptive sub-carrier allocation in an orthogonal frequency division multiple access (OFDMA) downlink transmission system. It also attempts to testify the high performance attitude on capacity compared to the latest available rate in other adaptive OFDMA methods, which maximizes the total system’s capacity and the total power in bit error rate (BER) constraints that are subject to proportional rate constraint (PRC). In this study the expectation value statistic scheduling was formed instead of the random numerical ordering during the first time of the sub-carrier allocation.  Furthermore, this scheme was developed via rate allocation, based on the PRC scheme to allocate the channel adaptively among users.  The rate of the allocation problem was also formulated to enhance the throughput.