The Performance Analysis Of Los Channel And Nlos Channel Of60Ghz System

60GHz millimeter-wave communications, which have many advantages such as high bandwidth, high transmission rate and high directivity, have been considered as one of the most promising wireless transmission technology in the future. According to whether exists obstacle between the sending and receiving ends,60GHz channel can be divided into two kinds:Line-of-Sight channels (LOS for short) and Not-Line-of-Sight channels (NLOS for short). The path-loss exponents in LOS channel are1.2-2.0and in NLOS channels are1.97-10. In order to study the propagation process of60GHz signal in different environments, we need to have performance analysis of LOS channel and NLOS channel under different application scenarios. Research results of this paper help to realize and popularize the application of60GHz device.This thesis intends to analyze the performance of LOS channel and NLOS channel in60GHz system under different application scenarios. The object of study mainly include two parts:one is the general model of60GHz system, the other is specific model of60GHz system. The general model does not take into account the channel characteristics and the specific parameters, and the specific model takes into account the channel parameters. The work of the thesis is as follows:(1) Based on the relationship between the power of the receiver, the sensitivity of the receiver and channel capacity, the dissertation makes a comparison of signal-to-noise ratio and channel capacity in LOS channel and NLOS channel of60GHz system under the same circumstances. Through the analysis, we may obtain the conclusion:under the same conditions, when the distance between the sender and the receiver increases, signal-to-noise ratio and channel capacity of NLOS channel decline more obviously than that of LOS channel.(2) In this article, an efficient method is suggested to improve the link quality, by using an artificial reflector under NLOS path so as to avoid significant path loss. The core of an artificial reflector is the calculation of the radar cross section. Radar cross section, which embodies the ability of scattering electromagnetic waves, is not the true area of object, but represents a kind of equivalent area. Through the simulation of60GHz communications in NLOS channel with an artificial reflector, LOS channel and NLOS channel, it can be seen:From the averaging perspective, the additional gain of10dB can be achieved by resorting to our suggested method compared with the NLOS case.(3) In order to study the LOS desktop environment of60GHz system, this paper discusses a modified SV-model. The modified SV-model combines the conventional SV-model with a well-known two-path model. According to the simulation results, the path loss of LOS desktop environment is the same as that of two-path environment. In order to verify the influence of an artificial reflector under NLOS desktop channel, the path loss of three channels are analyzed and compared, including NLOS channel with an artificial reflector, LOS channel and NLOS channel. The conclusion can be drawn the use of an artificial reflector will brings the channel gain of ten to twenty dB and also has the performance improvement of indoor NLOS desktop channel.(4) IEEE802.15.3c, one of the60GHz system standards, defines nine channel models (from CM1to CM9). We develop system model according to the channel characteristics and channel parameters given by IEEE802.15.3c standard and give a performance analysis of CM1, CM2, CM3and CM4. CM1and CM3belong to LOS channel. CM2and CM4belong to NLOS channel. Through a simulation, it can be obtained:the average value of RMS delay is1.189ns in CM1, the average value of RMS delay is3.758ns in CM2, the average value of RMS delay is 22.156ns in CM3, the average value of RMS delay is45.6ns in CM4. The RMS delay of LOS channel is lower than the that of NLOS channel.