A Direct Mode Operation Design and Simulation Applied to TD-LTE

Abstract

This paper offers a DMO (direct mode operation) design applied to TD-LTE. It can support point to point full-duplex communication in the no signal covered area and user switching according to their priority at the same time. The design divides channel into access channel and communication channel to improve the spectrum efficiency. When the SNR is higher than 16dB, the DMO design using QPSK modulation has a BER (bit error rate) reaching 10-4 under ITU-R M1225 channel B. Although at the same BER value, the SNR requirements of IFDMA has a 0.5dB lower than LFDMA, given that TD-LTE uses LFDMA and LFDMA has a good resistance to frequency offset and is much easier to realize, we adopt LFDMA as subcarrier mapping method in the DMO design. Besides, at the same BER value, the required SNR of MMSE (minimum mean square error) equalization is 1.0~1.5dB lower than the required SNR of the ZF (zero-forcing) equalization. Therefore DMO should use MMSE equalization in the low SNR environment and ZF equalization in the high SNR environment.