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

本文通过对无线传播和通信系统的分析，为千兆比特/秒无线局域网的实现做了研究工作。主要研究结果如下：1.室内无线传播测量和无线局域网模拟器利用新增波达方向测量功能的超宽带信道探测仪进行了室内无线传播测量。它发现了许多由金属物体引起的强镜面反射射线和许多弱散射射线。利用实测的时延分布，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。分集系统即使在静态环境下也表现出性能的改善.研究了千兆比特/秒无线通信系统中基于Viterbi译码度量的拉娜信道性能估计方法，并通过计算机仿真进行了验证，得到了有价值的结果。基于这个新频道 关于我们 EL估计方法，研究了两种基本的自适应速率通信系统。第一种采用自适应调制方式，实现了较快的平均传输速率，但硬件结构复杂;第二种采用自适应频率分集分支数系统，硬件规模相对较小，性能损失较小。并研究了它在自适应可变保护间隔OFDM系统中的应用。仿真结果表明，与传统的固定GI系统相比，该系统实现了更高的传输性能和效率，并进一步研究了利用子载波信道正交特性的MEMO-OFDM系统，表明其系统简单，传输性能与传统的空时编码MIMO系统相当。预计该系统将大幅降低功耗。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