Research On Channel Estimation Technique Of NGB Wireless System

The wireless system of Next Generation Broadcast network (NGB-W), coexistingwith China Mobile Multimedia Broadcasting(CMMB) business in the manner of timedivision multiplexing, aims to study how to fully utilize ultra-high frequency radioresources and transmit terrestrial broadcast signal. Its final target is completing theconvergence of radio broadcasting network and communication network. In order tomeet the higher demands of people on speed and quality for the future of broadcastcommunication, NGB-W uses the orthogonal frequency division multiplexing (OFDM)technology of high spectral efficiency and data transmission efficiency. As an importantpart of the OFDM system, Channel estimation module has a critical impact on theperformance of the entire system, it also is a necessary condition for coherentdemodulation of the receiver. This paper is related to the study of channel estimationtechniques in the project of "Technology research on wireless system of the NextGeneration Broadcast Network ".Firstly, this paper analyzes the effect of channel estimation module in the systemand the current status of research. Knowing the research on channel estimationtechniques requires a good knowledge of radio channel, so this paper first studied thebasic characteristics of the channel, then analyzed the impact of fading channel for thesystem, in which highlighted on the resulting small-scale fading due to multipath effects.Then this paper introduced OFDM technology, Bit-interleaved Coded Modulation(BICM), Multiple-Input Multiple-Output (MIMO) technology which were adopted inthe NGB-W system.Secondly, this paper introduced channel frequency response estimation algorithmfrom the following three steps: the design of pilot structure, the estimation of frequencyresponse on pilot symbols, the gain of frequency response on data symbols. Theestimation of frequency response on pilot symbols listed the following commonly usedestimation algorithms: Least Squares estimation (LS), Minimum Mean Square Errorestimation (MMSE), Singular Value Decomposition algorithm (SVD) and channelestimation algorithm based on DFT. The gain of frequency response on data symbolslisted the following commonly used interpolation algorithms: Linear interpolationalgorithm, interpolation algorithm based on the DFT and two-dimensional Wiener filtering algorithm. According to the application of Project realization, this paperintroduced the cascade method of two one-dimensional Wiener filtering in the fourthchapter.Finally, this paper gave the specific channel estimation design scheme of NGB-Wsystem, channel estimation scheme was simulated under Helsinki channel and TU6channel and analyzed accordingly. After performing floating-point emulation,Fixed-point simulation was conducted and the specific solution and simulation resultswere given.