The analysis of coded Overlapped Time Division Multiplexing system

This paper mainly focuses on evaluating performance of two coding schemes of Overlapped Time Division Multiplexing (OVTDM) system. One is using Turbo Product Code (TPC) as Forward Error Correcting (FEC) code, the other uses conventional Turbo code provided by Long Term Evolution (LTE) as a standard of comparison. Through analyzing uncoded OVTDM signal structure and its Bit Error Rate (BER) in low-to-moderate Signal to Noise Ratio (SNR), utilizing an FEC with fast iterative convergence behavior is a good choice. TPC satisfies the property of fast iterative convergence and is easy to be realized in hardware implementation, while turbo code is a relatively mature channel coding scheme in LTE. Simulation results show that TPC plus OVTDM (TPC-OVTDM) scheme outperforms LTE Turbo plus OVTDM (LTE-Turbo-OVTDM), TPC plus Quadrature Amplitude Modulation (TPC-QAM) and LTE Turbo plus QAM (LTE-Turbo-QAM) under the condition of short interleaver depth and same spectral efficiency. Moreover, with the increase of spectral efficiency, the TPC-OVTDM scheme can achieve greater coding gain. Furthermore, through comparing the performance of TPC-QAM with LTE-Turbo-QAM, the error correcting capability of TPC is better than that of LTE Turbo code. In addition, the TPC-OVTDM scheme makes system´s cardinality of signal constellation increase polynomially with spectral efficiency, rather than that of QAM signal which grows exponentially.