Applications of chaotic digital code division multiple access (CDMA) to cable communication systems

In this paper the technical details of chaotic digital code-division multiple access ((CD)(2)MA) communication systems used in cable communication systems are presented. The cable communication system may be a pure coaxial RF cable network, a hybrid fiber-coax network, or a pure optical fiber network for high-capacity data link. As an example of its many potential applications in cable communication systems, (CD)(2)MA is used to support the upstream digital data communications in cable TV systems occupying the very noisy 5-40 MHz portion of spectrum. Although the (CD)(2)MA proposed in this paper is only used to support current Internet services via cable TV networks, it can also be used to support the high-speed data-link provided in the 550-750 MI-It band in hybrid fiber-coax networks. (CD)(2)MA is a new communication framework which uses band-limited chaotic carriers instead of linear ones. For the purpose of generality, in this paper the band-limited chaotic carriers are approximated by groups of linear sub-carriers, which distribute within the same bandwidth with a fixed amplitude, random phases and uniformly distributed frequencies. The theoretical result of the performance of (CD)(2)MA is given. We also provide the simulation results of the bit-error-rate (BER) performances of a synchronous (CD)(2)MA used in cable communication systems. The results show that the (CD)(2)MA system has a better performance than the synchronous CDMA system proposed for the same cable communication system. Technical details of (CD)(2)MA are also presented for the future design of prototype systems. We present the framework of the whole (CD)(2)MA system including carrier synchronization, timing recovery and the details of nonlinear carrier generators.