An Efficient SNR Estimation Scheme For Secure Communication Over Fading Channel

Abstract: Secure transmission of confidential messages is a critical issue in communication systems and especially in wireless systems due to the broadcast nature of wireless transmissions.In order to address the two critical issues of security and energy-efficiency jointly, we study the secrecy capacity in the low-SNR regime. It is worthwhile to note that operation at low SNRs, in addition to improving the energy efficiency, is beneficial from a security perspective as well.We consider a general multiple-input and multiple-output (MIMO) channel model and identify the optimal transmission strategies in the low-SNR regime under secrecy constraints. It is very important to estimate the signal to noise ratio (SNR) of received signal and to transmit the signal effectively for the modern communication system. The performance of existing non-data-aided (NDA) SNR estimation methods are substantially degraded for high level modulation scheme such as M-ary amplitude and phase shift keying (APSK) or quadrature amplitude modulation (QAM).As an Extension we propose a SNR estimation method which uses zero point auto-correlation of received signal per block and auto/cross- correlation of decision feedback signal. Finally, the impact of fading is investigated, and the benefits of fading in terms of energy efficiency are shown.

Keywords: Secrecy capacity, QAM, SNR, MIMO