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

摘要

In this paper the technical details of chaotic digital code-division multiple access ((CD)~2MA) 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)~2MA 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)~2MA 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 MHz band in hybrid fiber-coax networks. (CD)~2MA 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)~2MA is given. We also provide the simulation results of the bit-error-rate (BER) performances of a synchronous (CD)~2MA used in cable communication systems. The results show that the (CD)~2MA system has a better performance than the synchronous CDMA system proposed for the same cable communication system. Technical details of (CD)~2MA are also presented for the future design of prototype systems. We present the framework of the whole (CD)~2MA system including carrier synchronization, timing recovery and the details of nonlinear carrier generators.