Diversity in synchronization for scheduled OFDM time-division cooperative transmission

An energy efficient synchronization method is presented for an OFDM-based Time Division Cooperative Transmission (TDCT) system for the purpose of range extension. The proposed algorithm operates on a novel preamble consisting of two OFDM symbols. In TDCT, copies of the packet are transmitted through different time slots. Exploiting dependence between the synchronization parameters of the different TDCT copies, the approach achieves diversity gain in all estimated synchronization parameters. Since the design and algorithm pertain only to the preamble, the method can be applied to decode-and-forward as well as amplify-and-forward TDCT schemes. This algorithm also offers a significant performance improvement to the single-input-and-single-out (SISO) communication system. Through computer simulation, we show that our novel TDCT approach achieves synchronization in the context of range extension, avoiding the need for more preamble energy.