A novel broadband wireless OFDMA scheme for downlink in cellular communications

A new air interface scheme based on adaptive resource allocation method is proposed for downlink in cellular OFDM systems. The proposed method is featured as a novel technique for high spectral efficiency (i.e. frequency reuse factor approaching one) and high power efficiency. In order to reduce the co-channel interference (CCI) and improve the capacity in a cell, a cell is partitioned into three 120° sectors and three adjacent sectors from different cells are composed as a "virtual cell" which is centrally controlled. Assuming knowledge of instantaneous channel information for all sub-channels, bit rates and quality of service (QoS) requirements of all active users in base-stations (BSs), an adaptive resource allocations based wireless multi-user OFDM access is employed independently in each "virtual cell" by using the techniques such as multi-user diversity, interference measurement and bad channel avoidance over the whole system bandwidth. It is demonstrated that the system performance is greatly improved compared to the traditional systems with fixed channel allocation in cellular communications.