Channel Evaluation Design Of OFDM System Based On Matlab

The research background of this paper is based on the development of CMTS product based on DOCSIS3.1.In the 2015 ICTC conference report, a speech named "welcome to DOCSIS3.1" announced the arrival of DOCSIS3.1. DOCSIS3.1 is next generation access technology used by CMTS devices which widely accepted by the international. It uses the latest technology in physical layer technology in recent years, such as OFDM, OFDMA, LDPC encoding and decoding, which greatly improves the signal transmission rate on coaxial cable. OFDM(orthogonal frequency division multiplexing) is a kind of efficient sp ecial multi carrier modulation technology which can resist the multipath propagation effectively, and it has strong anti-jamming performance. This technology has obtained widespread application in the field of mobile communication, digital TV and digital broadcasting.In the development and deployment of CMTS, it is an urgent need problem that how to optimize and adjust the transmission parameters according to the channel characteristics of different users or segment. So this paper will analyze the architecture of OFDM which is used in CMTS system, and design new algorithm to analyze the signal before it has been demodulated in receiving end. Specifically speaking, we will carry out channel evaluation by means of MER(modulation error ratio). MER can represent a single "quality factor" of the received signal, which is often used as an early indication of the receiver’s signal can be correctly decoded. Generally speaking, when we calculate the MER, we need to known the received signal and transmitted signal. But the transmitted signal is often unknown due to various reasons in the actual situation. So this paper will mainly studies how to detect the blind MER in receiving terminal in the case of unknown transmitted signal and use the value of MER to evaluate the channel. In order to create a more friendly user interface, the paper will allow the user to carry out MER detection in receiving terminal based on arbitrary segments and arbitrary size of received data. In the end, this paper will do the large data analysis on the results of several calculations including the determination of confidence interval. The result will be simulated and verificated on Matlab in the end. In a word, this paper has important significance for channel estimation, robust reception of data and support DOCSIS3.1 CMTS system development and the new standard of research.