The CSO (composite second-order distortion) induced by self-phase modulation (SPM) in an AM-VSB externally modulated CATV system which employs optical fiber Raman amplifiers (FRA) is studied theoretically in this paper. Firstly, the analysis of CSO is achieved by solving Schrödinger equation using perturbation method. And then numerical results are presented and discussed. According to the study in the paper, the SPM induced CSO performance can be improved by more than 10 dB by using FRA than using EDFA in CATV systems.
Many network architectures have been designed for the future high capacity transmission. Hybrid Opto-electronic Ring NETwork (HORNET), a kind of IP/WDM metro network, is one of them. The inherent defects in WDM network, like unfairness and low efficient, are conquered by using Distributed Queue Bidirectional Ring (DQBR). But that way with a high complexity is difficult to be realized both in hardware and software. In this paper, a modified Round Robin scheme, called Simple Round Robin (SRR) with configuration is proposed and simulated in HORNET. Round Robin is a comprehensively researched method to solve the unfairness, and with low complexity, but much low efficient. SRR aims to realize the fairness control, and achieve a high throughput with accurately designing and initializing as well. It seems satisfactory that SRR with config does well both in fairness and efficiency.