Secure OFDM based on Coupled Linear Congruential Generator and its FPGA Prototype

Orthogonal frequency division multiplexing (OFDM) is a promising technology for 4G, 5G and IoT applications. In OFDM, physical layer security is an important aspect due to increased data traffic, and number of users. But most of the security features are performed in the medium access control (MAC) layer and the transmissions at physical layer are highly susceptible to the eavesdropping. Scrambler associated with OFDM scheme is only used for avoiding long sequence of ones or zeros in the input data by employing linear feedback shift register (LFSR). In this paper, LFSR is replaced with secured pseudorandom bit generator (PRBG) i.e., coupled linear congruential generator (CLCG) in the scrambler/ descrambler module that adds security features in the physical layer and performs scrambling as well. All the NIST tests are performed that demonstrates CLCG is better than LFSR in terms of randomness and security. Therefore, an efficient hardware architectural design and implementation methodology of the proposed scheme i.e., CLCG based secure OFDM for an application of 802.11a is demonstrated in this paper. The baseband transceiver modules of CLCG based secure OFDM along with AWGN channel are prototyped on commercially available virtex xc5vlx110t-l FPGA device. The bit error rate (BER) and peak to average power ratio (PAPR) performance of the proposed scheme are also studied.