| The goal of wireless mobile communication system will be to achieve high-quality, high-speed mobile multimedia and data transmission business. Orthogonal Frequency Division Multiplexing (OFDM) has been applied widely because of its high spectrum utilization and efficiency of information transmission, as well as a strong anti-multi-path fading in wireless communications. Wireless mobile channel is the most complex channel in the modern communication systems, and it is also an important factor that restricts system performance. Since the channel of the OFDM system has frequency selective and time-varying character-rustics. It is necessary to estimate channel so that the channel state information can be obtained in time at receive point and coherent demodulation is accurate realized in real-time. The paper mainly studies the OFDM system channel estimation algorithm based on pilot assistant.Based on analysis of channel estimation algorithm using traditional DFT transform domain, new channel estimation is proposed based on windowed DCT-IV transform Windowed. Sinusoidal is used to inhibit spectrum leakage of channel impulse response. Then, a low-pass filter is designed in the DCT transform domain. High frequency noise is eliminated through the dynamical cut-off frequency of filter. Symmetric characteristics of DCT transform is used to eliminate edge effects; The pilot quantity can be reduced and the utilization of channel can be improved because the energy of DCT-IV transform is more concentrative than DFT transform; More, the computing complexity can be reduced because DCT transform is a real operator. The simulation results show that the algorithm is superior to the traditional channel estimation algorithm based on DFT transform in the multi-path fading channel, which is available and effective channel estimation algorithm.A new de-noising improved channel estimation algorithm is proposed based on the DCT-IV transform domain because low-pass filter's cut-off frequency can not be accurately estimated. First, the phase noise can be eliminated for synchronize bias by phase compensation the location of the pilot channel estimation value. Then, the channel impulse response noise power and inter-carrier interference residual power of the transform domain can be effectively inhibited by tracking the channel impulse energy response and selecting the appropriate parameters. Therefore, the channel estimation performance is enhanced. Experimental result shows the bit error rate of OFDM system is reduced effectively. |
