Secret key transmission for OFDM based machine type communications

Machine type communications (MTC) play a crucial role in the Internet of things (IoT) where a number of devices are connected by wireless communications. Unfortunately, wireless communications are prone to various security threats including eavesdropping due to the broadcast nature. In this paper, we propose an approach that can generate a sequence of random numbers for a secret-key in an orthogonal frequency division multiplexing (OFDM) system. Since the random key is based on channel dependent signature (CDS) and generated without any predetermined sequences, a device can have a unique secret-key in the proposed approach, which suits to MTC for secure communications. The resulting approach is called CDS based secure OFDM (CDSSOFDM). We also modify the CDS-SOFDM scheme to transmit more bits using multiple blocks.