对MIMO-OFDM无线系统的误码率评估

　　In today’s commercial wireless communication systems， we need higher data rates and high transmission reliability to meet increasing demand for multimedia applications such as high quality audio and video. In present day’s communication， OFDM is a widespread and one of the most promising multi-carrier multiplexing methods for the transmission of wireless signals ［1，2］。 The OFDM allows transmitting of many parallel narrow subchannels enough to eliminate the effect of delay spread. It converts a frequency-selective fading channel into a collection of parallel subchannels， which significantly simplifies the structure of the receiver. Orthogonality of subcarriers is the main idea involved in OFDM that allows simultaneous transmission of a lot of subcarriers in a high frequency space without interference from each other though they overlap spectrally. Consequently， OFDM handles the multipath interference at the receiver along with offers spectral efficiency and handles high speed data streams on a multipath fading environment that causes ISI ［3–5］。 Furthermore， OFDM reduces inter symbol interference （ISI） and inter channel interference （ICI） by use of cyclic prefix （CP） ［6］。 Inclusion of CP， converts the action of the channel on the transmitted signal from a linear convolution into the cyclic convolution; so that the overall produced transfer function can be diagonalized by the use of an IFFT at the transmitter and the FFT at the receiver end. CP needs to be long enough to hold the delay spread of the channel ［7］。 But， the other network