A mapping technique for Space Shift Keying with arbitrary number of transmit antennas

A major problem in the Space Shift Keying (SSK) modulation technique is that the transmitter must be equipped by a number of transmit antennas that is a power of two. Even in Generalized Space Shift Keying (GSSK), the number of combinations between the active transmit antennas should be a power of two. Such a problem adds a constraint on the transmitter design and limits the achievable spectral efficiency. In this paper, a novel mapping method for SSK (or GSSK) is proposed in order to overcome such a problem, and consequently, any arbitrary number of transmit antennas can be used. Despite of its simplicity, it is able to significantly improve the spectral efficiency with a slight increase in the bit error rate under low SNR regimes, compared to the conventional mapping method.