Direct-Sequence Spread Spectrum with Variable Spreading Sequence for Jamming Immunity

Jamming attacks can limit the availability of wireless networks and can lead to significant re-transmissions and increased power consumption. Over the past decades DSSS has been utilized to consolidate jamming-resistant communication. Such a system is relatively immune to jamming interference when the spreading sequence is unknown to the jammer. However, the cyclostationary behavior of the spreading sequence can be exploited by the jammer to identify the spreading sequence and hence completely jam the system. In this paper, a DSSS system using variable spreading sequence is proposed. The proposed system uses a shared secret key with appropriate ciphers like AES for selection of variable spreading sequence. Each bit is spread by a different spreading sequence resulting in jamming immunity. In addition, the proposed system uses a coarse time and date based plaintext after regular intervals to achieve synchronization between transmitter and receiver. Simulation results show the synchronization and bit error rate performance of the proposed system in the presence of different types of jammers.