Permutation-based DCSK and multiple-access DCSK systems

This paper presents a method for enhancing the differential chaos-shift-keying (DCSK) and multiple access DCSK systems. By introducing a permutation transformation which destroys the similarity between the reference and data samples in a DCSK system, the bit rate can be made undetectable from the frequency spectrum, thereby enhancing the data security. Using different transformations for different users, the interference between users in a multiple-access system can be minimized, and each symbol is ensured to be sent within one bit duration for all users. Furthermore, the implementation requires only slight modification to the original DCSK system.