Enhanced Differential Spatial Modulation

Spatial modulation(SM) is a newly-emerging multi-input multi-output(MIMO) technology, which is characterized only activates a single transmitting antenna in any time slot, and uses the activated antenna sending additional information symbols. However, because of these characteristics, the spatial modulation must know the channel state information(CSI) advanced. Then do the demodulation process at the receiver. However, channel estimation and symbol detection are difficult to control, which will cause the demodulation process very complex of the spatial modulation system, the performance loss will also become more and more serious. Based on this situation, a differential spatial modulation(DSM) technique is proposed. This technique remains a characteristic of a single antenna is activated in any time slot, but do not need to the channel estimate at the transmitter to the receiver, that make up for the lack of space modulation technique. The differential spatial modulation technique is also applicable to any constant energy constellation(for example: phase shift keying phase-shift keying, PSK), an arbitrary number of transmit antennas and receive antennas system. With the same spectral efficiency, the proposed scheme is capable of paying no more than 3dB signal-to-noise ratio penalty compared with SM.This paper has put forward two optimization scheme of Differential Space Shift Keying(DSSK) system at the transmitter encoding, and do further optimization on this basis to achieve an enhanced Spatial Differential Modulation system. Wherein, DSSK is a special case of DSM. When the symbol modulation of DSM is not considered, DSM system is called DSSK system. The first scheme is based on Gray coding idea called Gray Code Order, which is an optical algorithm of the antennas activation sequence without considering the modulation symbols, i.e. DSSK system, which can improve the coding gain of the system. In addition, the author also explain the effect of coding gain with the number of receive antennas increases gradually weakened from algorithms and simulation experiments. The second scheme is improved on the Gray Code Order, called Intersected Gray Code Order. The purpose of the proposed algorithm is to improve transmit diversity gain in DSSK system. Considering that the DSM system not only involving the antennas activation sequence encoding, but comprising a symbol modulator. In order to propose an enhanced system of DSM, only optimize the antennas activation sequence encoding algorithm is not able to improve system performance overall. Therefore, basing on the Intersected Gray Code Order, the author proposed the method that rotation the modulation constellation of modulated symbol a certain angle, then based on constellation rotation and the Coordinate Interleaving(CI) algorithm idea, do the CI process in the final form of the block adjacent to transmit modulation symbols, and ultimately improving the diversity gain of DSM system. In the equal SNR(Signal to Noise Ratio, SNR) of the case, this scheme can greatly reduce the Bit Error Rate(BER).