Smart Antenna Technology in High-Speed Wireless Access Communications Using the OFDM Scheme

本研究项目研究OFDM方案下高速无线通信中基于dbf的高性能智能天线系统。研究的主要目的是为下一代无线通信系统减少OFDM系统中衰落和干扰的影响。从2001年到2002年的研究结果总结如下：1。讨论了OFDM系统中多载波KMA （MC-KMA）自适应阵列的性能。该算法利用FFT处理后的频域数据，在保护间隔内接收所需波（同步信号）和延迟波，同时抑制其他波。结果表明，由于期望信号的接收功率增加，该系统具有较好的性能。提出了基于递归ESPRIT算法的OFDM系统自适应均衡器。计算机仿真结果表明，该方法在静态环境和多瑞利衰落环境下均能取得理想的性能，证明了该方法的有效性。当接收到超出保护间隔的长延时多径波时，OFEM频谱的正交性被破坏。从这个角度出发，我们提出了零载波不传输数据的优化方法，并通过计算机仿真观察到了有趣的性能。研究了用于OFDM传输的MMSE自适应阵列。本文提出的自适应阵列通过FFT处理逐个子载波控制阵列权重。当导频符号以等间距插入到指定的子载波上时，利用插值技术可以在没有导频符号的子载波上产生接收信号，然后利用这些接收信号和导频符号共同产生所有子载波的最优阵列权值。计算机仿真结果表明，该算法的输出信噪比和误码率与将导频符号插入所有子载波的算法的输出信噪比和误码率基本相等。少

This research project deals with high-function DBF-based smart antenna systems in high-speed wireless communications using the OFDM scheme. The main objective of the research is to reduce the effects of fading and interference in the OFDM systems for the next generation wireless communication systems. The research results obtained from 2001 to 2002 are summarized below.1. The performance of Multi-Carrier KMA (MC-KMA) adaptive array for the OFDM system has been discussed. With the frequency-domain data after FFT processing, this algorithm operates to receive the desired wave (synchronized signal) and delayed waves within a guard interval while suppressing other waves. It is confirmed that the proposed system has better performance because of increased received power of the desired signal.2. We proposed the adaptive equalizer with the recursive ESPRIT algorithm for the OFDM system. Via computer simulation, it is shown that the ideal performance is obtained in the static environments and … More Rayleigh fading environments, and as a result the proposed method is found to be much effective.3. When the multipath waves with long delay time beyond the guard interval are received, the orthogonality of the OFEM spectrum is destroyed. From the viewpoint, we proposed the optimization method using zero carriers which transmits no data, and the interesting performance has been observed through computer simulation.4. The MMSE adaptive array for OFDM transmission has been considered. The adaptive array proposed herein controls array weights subcarrier by subcarrier after FFT processing. When pilot symbols are inserted at specified subcarriers with equal spacing, an interpolation technique can generate received signals at subcarriers with no pilot symbols and then using these received signals and pilot symbols together produces optimum array weights for all subcarriers. Computer simulation results show that performance of the proposed algorithm is nearly equal in the output SINR and BER to that of the algorithm in which pilot symbols are inserted into all subcarriers. Less