Secure information transmission in filter bank multi-carrier spread spectrum systems

This paper presents a novel method for generating a secret key to augment the security of spread spectrum systems. The proposed key generation takes advantage of the channel reciprocity exhibited between two communicating parties. We validate the key generation aspect of our system by using real-world measurements. We note that the strongest path in the channel impulse response can be the main source that will allow an adversary to generate a similar key to those of the legitimate nodes. We resolve this problem by introducing an augmentation that removes the strongest path from the channel impulse response before key generation. This augmentation, that we call strongest path cancellation (SPC), is found very effective. We also note that the generated keys need not be perfectly the same at the legitimate nodes, hence, the proposed method belongs to the class of fault tolerant secure communications. In this paper, without any loss of generality, we use the proposed key generation method as part of a filter bank multicarrier spread spectrum (FB-MC-SS) system, where robust performance against narrow and/or partial band interference is also guaranteed.