Research And Modeling Of The Noise Characteristic On The Upstream Channel For Hfc Network

Network operators are most concerned about its reliability while a network is in operation. However, upstream channels'reliability has being challenged by several kinds of noise and interference and the accumulation of noise due to the tree and branch architecture of the coaxial access network. In order to improve the reliability for upstream channel and the efficiency of network maintenance, we must study the features of damage signals for actual HFC upstream channels, and get the main features of some typical kind of noise and interference in the HFC upstream network.Through the real-time signals'capture and analysis, several parameters of the noise and interference for the HFC upstream channel, which are given in forms of spectrum and constellation, can be easily found in this paper. And then it offers the features and types of signals'injury caused by typical noise and interference in this paper, which take a long time for observation and statistical analysis. Based on these research results, several mathematical models have been formed, which focus on the feature function models for the Gaussian White Noise and the Narrowband Noise. And then the fast series expansion method has been used to calculate the BER of HFC upstream channels, which based on the noise feature function models. And finally it develops the BER-CNR curves of the QPSK and 16QAM systems under the influence of typical noise and interference, which are called Falls Curves, with the help of MATLAB simulation tools.The feature function models and their simulation results have been proved to be right, by comparing with features of the actual HFC upstream channel. And the research process to get the final results has based on the theory and principles of the Basis of Random Process and the Digital Communications, which have been proved to be right. So the research results in this paper are correct and reasonable.In this paper, it gives the main features of some typical noise and interference, and also offers their feature function models, and finally obtains the simulation results based on these models, which can be very useful for further study of the noise and interference for the upstream channel in HFC network.