The analyses on indoor wireless environments and the transmission performance of giga-bit wireless LAN

通过对无线传输和通信系统的分析，为实现千兆无线局域网做了研究工作。实验结果如下：室内无线传播测量和无线局域网模拟器室内无线传播测量采用新增DOA测量功能的超宽带信道测深仪。它发现了许多由金属物体引起的强反射光线和许多弱散射光线。利用测量到的延迟曲线，研究了室内传播信道模拟器，并将其用于MIMO分集系统的性能研究。即使在静态环境下，分集系统的性能也有所提高。提出了一种基于viterbi解码指标的千兆比特/s无线局域网通信系统简单信道性能估计方法，并通过计算机仿真进行了评价，取得了有价值的结果。基于这种新的信道估计方法，研究了两种基本的自适应速率通信系统。采用自适应调制方案的第一种系统在硬件结构复杂的情况下实现了较快的平均传输速率，而采用自适应分频系统的第二种系统在硬件规模较小的情况下实现了较小的性能损失。其次，提出并研究了一种基于同相信道失真检测器的高精度时延差估计方法。并研究了其在自适应变保护间隔OFDM系统中的应用。仿真结果表明，与传统的固定GI系统相比，该系统实现了较高的传输性能和效率。此外，还研究了一种利用子载波信道正交特性的MEMO-OFDM系统，与传统空时编码MIMO系统相比，系统简单且传输性能相当。该系统有望大幅降低电力消耗。少

This research work has been done for the realization of Giga-bit/s wireless LAN by both analyses on wireless propagation and communication system. Following results were obtained.1. Indoor wireless propagation measurements and wireless LAN simulatorIndoor wireless propagation measurements have been done by using the ultra wide-band channel sounder with newly added DOA measuring function. It found many strong specular rays caused by the metallic objects and so many weak scattering rays. By utilizing the measured delay profiles, the indoor propagation channel simulator has been studied and used for the performance investigation of MIMO diversity system. The diversity system showed the performance improvement even in the static environment.2. Studies on Giga-bit/s communication system for wireless LANA simple channel performance estimation method based on the viterbi decoding metrics has been proposed and evaluated by computer simulations with the valuable results. Based on this new chann … More el estimation method, two basic adaptive rate communication systems have been studied. The first one with adaptive modulation schemes has realized a fast average transmission rate with complex hardware architecture, however, the second one with adaptive frequency diversity branch number system has obtained a relatively small scale hardware with small loss of performance.In the next, a high-precision time-delay difference estimation method based on the in-phase channel distortion detector has been proposed and studied. And its application to the adaptive variable guard-interval (GI) OFDM system has been studied. The simulation result showed that the system has realized the high transmission performance and efficiency compared with conventional fixed GI system.And furthermore, a MEMO-OFDM system utilizing the sub-carrier channel orthogonal property has been studied to show its system simplicity and the comparable transmission performance compared with conventional space-time coding MIMO system. The proposed system is expected to cut the power consumption in big amount. Less