Multi-cell communications for OFDM-based asynchronous networks over multi-cell environments

This paper investigates a multi-cell communication technique for OFDM (Orthogonal Frequency Division Multiplexing)-based asynchronous networks without the use of a GPS (Global Positioning System). First, a downlink macro-diversity technique using bandwidth division allocation is presented, where each MS (Mobile Station) simultaneously receives control information from surrounding BSs (Base Stations) using an FFT (Fast Fourier Transform) module. Second, a hierarchical master-slave synchronization technique is introduced for plug & access network synchronization. Finally, an adaptive guard carrier allocation scheme is proposed to reduce the effect of MAI (Multiple Access Interference) for users receiving multiple transmission signals from surrounding BSs. In a simulation, the proposed technique is well designed to achieve SSDT (Site Selection Diversity Transmission) and adaptive synchronization for OFDM-based networks. It is particularly noteworthy that this adaptive sub-carrier allocation is very effective in reducing MAI for plug and access network synchronization.