SSK-Sequence Modulation: A Study of Secrecy Rate and Receiver Computational Complexity

Sequence modulation (SqM) is a digital transmission technique that uses transmission entities such as frequency sub-carriers, antenna indexing, and constellation symbols sequentially to convey information in multi-antenna systems. In this work, we focus on space shift keying (SSK) based sequence modulation (SSK-SqM) in relation to secrecy rate and receiver computational complexity analysis. By adopting information-theoretic method based on sample variance (SV) of receiver detector noise and relative entropy from the probabilistic distance to find bits in error for the SSK-SqM scheme, we are able to develop a close-form equation for mutual information (MI) and hence find numerical secrecy rates for SSK-SqM. The SV and MI criteria are validated using numerical simulation. The secrecy rate of SSK-SqM is analyzed in various fashion; increasing the number of antennas at the legitimate receiver and the eavesdropper, at various signal to noise ratio (SNR). The secrecy rate of SSK-SqM was then compared to classical SSK and 4-QAM single-input multiple-output (SIMO).