Design And Implementation Of Cross-layer CTC

With the rapid popularization of the Internet of things,WiFi,ZigBee,Bluetooth and other wireless technologies with different communication protocols are widely used in various fields such as environmental detection,positioning,smart home and so on.These wireless technologies continue to expand their application space,and gradually form the form of dense coexistence of multiple network protocols in the same space,making cross-technology-communication(CTC)become an urgent need.Traditional heterogeneous communication technology realizes cross-technology-communication between heterogeneous devices through gateway design,but this will put forward higher requirements for system hardware design.In addition,the complex coexistence of wireless transmission environment will inevitably cause interference between devices,and the existing work mainly focuses on the cross-technology-communication method of modifying physical layer between devices without interference.Therefore,this paper studies the impact of ZigBee uplink communication to WiFi in the presence of strong WiFi interference.The main research work is summarized as follows:Firstly,aiming at the serious packet loss problem caused by strong WiFi interference in the surrounding environment,this paper proposes a channel sensing energy detection method in link layer.By adjusting the signal transmission power of WiFi transmitter to make its transmission power far greater than the surrounding interference WiFi source,ZigBee judges whether the WiFi transmitter is occupying the channel by detecting the strength of the current channel received by the network card.Secondly,a request-response mechanism between ZigBee and WiFi is established to solve the problem that due to the continuous transmission of signals by WiFi transmitter,the data packets sent by ZigBee are lost.When receiving a ZigBee request to send a signal,the WiFi receiver will pause the communication with the other WiFi transmitters,creating a short "green channel" for the ZigBee node.Thirdly,aiming at the problem that WiFi receiver can not coordinate with homogeneous WiFi and heterogeneous ZigBee communication,in this paper,frequency hopping communication is used to realize the hopping reception between WiFi transmitter and ZigBee transmitter.Finally,GNU radio and USRP N210 are used to build the system prototype.In the prototype system test,WiFi-to-WiFi,ZigBee-to-ZigBee and ZigBee-to-WiFi heterogeneous communication are tested respectively.Then the packet loss rate of cross-technology-communication link in the presence of strong WiFi interference is tested.The test results show that the packet loss rate reaches 60% when there is strong WiFi interference.