建筑物内WLAN远程无障碍通讯技术研究

None obstruction long-distance WLAN telecommunication research in buildings

本文分析广播式无线局域网(WLAN)室内通讯数据丢包、信号盲点和连接不上等问题与微波多路径传播延迟间的关系,以及波的干涉效应,认为双镜面反射形成的波导效应对室内通讯造成严重影响,障碍物造成波前畸变。这影响了网络化仪器的可靠性及其在现场测试中的应用。提出用指向性好的定向天线,并利用狭长走廊空间远距离传输电磁波。用2个相反指向的天线可获得传播线度140m以上。引入角反射器将信号导入远端室内,以克服微波屏障问题。角反射器的投影尺寸须大于波长λ。针对发生在路由器接收端上的大量丢包,提高无线网卡定向发射能力和增益;更换网卡天线,用λ天线代替λ／2天线抑制垂直波面宽度,将全向天线增加反射面改造成定向天线。模拟计算120°反射面在20°前向辐射角的情况下,增益8．4dB。选用500mW发射功率的路由器可提高室内远程通讯能力近1倍。走廊末端墙面修饰成多棱角,可降低垂直入射的反射波。本技术可用于运动部件无线测量和智能仪器现场组网等场合。

This paper analyzes problems of lost packets, the signal blind spots and disconnect to wireless locate area network (WLAN) in the telecommunication indoors. It is the relation with microwave delay by multi-path and the interference effect. It thinks that affects seriously in the telecommunication indoors which the waveguide effect forming from a double specular reflection such as the ceiling and floor. Impediment causes the distortion of wavefront It affects the reliability and the application in the field measurements with the network instruments. It puts forward a sharp uni-direction antenna to transmit electromagnetic wave in the long-distance, narrow hallway. It can cover over 140m length with 2 contrary direction aerials. Put the angle reflectors on the hallway wall joins signal between terminal rooms and a wireless router. It overcomes the microwave natural cover problems. And the reflector projective section must be >λ. Improve the uni-direction transmitted ability and gain with wireless network cards against lost a mount of packets at the router receiver. Replace the network card aerial; restraint perpendicular wavefront width by theλaerial instead of the X/2 one, reform the omnidirectional antenna into directional one by adding a reflector. 20 forward radiation is the 8.4 dB gain with 120 reflector by simulation.It can get nearly 2 times of long-distance communication indoors with a 500mW power router. The poly-prism on the terminal wall at the hallway can lower the vertical reflected wave. It is useful in wireless measurement of the motion components and smart instrument net, etc.