Advanced Hybrid OFDM System with Multi-Layer TDD Architecture

Various hybrid duplexing techniques have been proposed to accommodate asymmetric multimedia services for next generation cellular systems. Many of them apply time division duplexing (TDD) technology in the inner cell region and frequency division duplexing technology in the outer region. One concern for such arrangement would be mitigating the intercell interference. They need, however, to use a fairly long guard time between uplink and downlink portion of a frame, because of the propagation time from the base station (BS) to the farthest mobile station (MS) in the TDD region. Such inefficiency becomes exaggerated when the raw data rate increases. We propose a multi-layer TDD architecture which includes several concentric TDD regions having different guard times. The proposed architecture has been proven by computer simulation that it has much smaller average delay when there is a mixture of multimedia traffic, and it accommodates more traffic having with different requirements of maximally allowable delay.