A New Parametric DFT-Based OFDM Transceiver for Intrinsic Wireless Communication Encryption

Abstract

In this paper, we propose a parametric OFDM transceiver for wireless communication encryption. One of the major contributions of this work is the intrinsic encryption nature of the proposed system, since it is a completely new idea and philosophically different from the concept of existing secured OFDM systems requiring separate encryption blocks. The main idea behind the proposed system is the appropriate use of the parametric discrete Fourier transform (DFT-alpha) and its inverse IDFT-alpha, where alpha is randomly obtained from [-2pi, 0], to implement the OFDM system and at the same time inherently encrypt the communications. Thus, the resulting (IDFT-alpha/DFT-alpha)-based OFDM transceiver, which has a performance similar to that of the conventional IDFT/DFT-based OFDM transceiver, is applied and implemented in the IEEE 802.11a WIFI system framework OFDM for communication encrypting. Moreover, using BER and SNR, we experimentally determine the appropriate intervals of the possible values of alpha for perfect encryption in a flat fading channel assumed for optimal testing environment. We also examine and assess the effects of DFT-alpha on the transformation of the constellation pattern of the transmitted signal to prove the validity of the obtained intervals for different modulation schemes such as BPSK, QPSK, 16QAM, and 64QAM.

Keywords

• communication systems security
• discrete fourier transform
• encryption
• ofdm
• wireless communication