Windowing Technology Improves The ICI Performance Of Cooperative OFDM System

The orthogonal frequency division multiplexing(OFDM) is introduced into Cooperative communication system can not only increase the capacity of the channel, but also against multipath interference and improve the communication quality.But during communication process the OFDM system is influenced by the frequency offset and destroy the orthogonality among the subcarriers. It leds to the inter-carrier interference(ICI) of the subchannel.In Cooperative communication system It exists a lot of carrier frequency offset (CFO). It inevitable aggravates the bad impact of ICI on the Cooperative communication system.In this paper it introduce a method–domain Nyquist windowing technology. The application of window functions can reduce the impact of the ICI. The paper completed work as follows:Firstly,It describes the principles and knowledge of the OFDM system, Cooperative communication systems and Cooperative OFDM system in details,prepare to introduction the technology of Windowing technique.Secondly,It analysises of the time damain and frequency domain characteristics of the general windows,also makes a detailed time-domain and frequency-domain maps;It take the raised cosine window for example to illustrate that Windowing technology can improve the ICI performance of OFDM system.Thirdly,respectively build the block diagram and simulation environment of the AF/DF- Cooperative OFDM window system.It studies that Windowing technology how to offset the impact of the system ICI and improve CIR of the system under the Cooperative OFDM system. Simulation results show that:Whether in AF-Cooperative system or DF-Cooperative system,The (BTRC) can best inhibit the ICI and improve the CIR. When using the same window function,under low frequency offset,the performance of the DF- Cooperative OFDM system is better than the AF- Cooperative OFDM system; under high frequency offset, the situation is reversed, the performance of the AF- Cooperative OFDM system is better. Results suggest that Windowing technology can effectively inhibit the impact of ICI in cooperative OFDM systems, and improve the CIR.