Research On Suppression Technology Of WiFi Signal In ISM Frequency Band

With the continuous development of wireless communication,wireless spectrum resources become increasingly scarce.In this context,the ISM band without authorization has gradually entered our vision.WiFi system(802.11 protocol family)is the most widely used communication system in ISM band.WiFi system has the characteristics of wide distribution,easy deployment and no unified central control,which will cause serious interference to the communication system coexisting in the same band.At the same time,in the security management and control scenario,the problem of no unified central control will be managed.Controlling WiFi communication behavior poses great challenges.Therefore,in order to deal with the above problems of ISM band WiFi signal,this paper studies the suppression technology of ISM band WiFi signal.The main work and contributions of this paper are as follows:Firstly,the interference in ISM band is analyzed and studied in this paper.At present,there are many communication systems in ISM band,including wireless LAN WiFi(802.11 series protocol),Bluetooth,ZigBee(802.15.4),etc.WiFi system is widely distributed.WiFi system has the characteristics of wider channel,stronger overlap of adjacent channel bands and higher transmission power than other communication systems,so WiFi is the most important interference source in ISM band.Secondly,a WiFi Suppression(WiS)method in ISM band is proposed.WiS can suppress the communication behavior of WiFi devices by sending combined suppression signals and obtain a predetermined suppression time.On this basis,aiming at the scene of channel overlap,channel expansion and fierce competition among multiple devices,a multi-frame and multi-channel suppression method is proposed to further enhance the suppression effect of WiFi signals.A variety of existing commercial WiFi access devices are tested in detail.The test results show that WiS suppression technology performs better in universality,energy consumption and other aspects than the existing related technologies.Finally,in LTE-U(LTE unlicensed)scenario,combined with the WiS interference suppression method proposed in this paper,a novel LTE-U and WiFi duty cycle coexistence technology based on WiS is proposed.The traditional duty cycle technology is optimized,which not only retains the advantage of time-domain separation between LTE-U system and WiFi system in traditional duty cycle technology to avoid interference,but also through WiS interference suppression technology.By using this technology,the coexistence technology based on duty cycle can get rid of the limitation of the need for central control nodes and minimize the interference between LTE-U system and WiFi system at low cost.