Channel-based mapping diversity for enhancing the physical layer security in the Internet of Things

Demand of minimal hardware requirement and low energy consumption for internet of things (IoT) has gained the importance of techniques enhancing the physical layer security. Looking at this, we propose a channel-based mapping diversity (CBMD) scheme for a source (S), destination (D) pair to increase the average bit error rate (ABER) at an eavesdropper (E). CBMD leads to an ABER of 0.5 at E when the channels between S - D and S - E are independent. In the case where S - D and S - E are correlated (due to the proximity of E at D), we derive an optimal strategy at E which leads to the best performance at E. We also derive an optimal strategy at S, assuming E uses its optimal strategy, thereby, considering the worst case scenario. A sub-optimal strategy is also proposed at S which does not require any statistical information about the link S - E and hence, has low implementation complexity. We analyze the variation of ABER at E with the signal to noise ratio (SNR) and the channel correlation coefficient. Our simulation results demonstrate that CBMD indeed leads to significant performance degradation at E even at moderate channel correlation for a properly chosen strategy.