Low-power wide area network(LPWAN)has developed rapidly in recent years and is widely used in various Internet of Things(IoT)services.In order to reduce cost and power consumption,wide coverage,LPWAN tends to use simp...Low-power wide area network(LPWAN)has developed rapidly in recent years and is widely used in various Internet of Things(IoT)services.In order to reduce cost and power consumption,wide coverage,LPWAN tends to use simple channel access control protocols,such as the Aloha protocol.This protocol is simple with poor extension capability.In high-density environment,Aloha protocol will lead to low channel utilization,prolonged access and high conflict probability.Therefore,in order to solve the above problems,we propose an enhanced channel access control mechanism based on the existing LoRaWAN protocol,that is,a dynamic listening backoff mechanism.We combine the improved“listen first and then talk”(LBT)mechanism with the current state of the channel to adaptively adjust the size of the backoff window.The theoretical analysis and simulation results show that the proposed mechanism have a better performance than the existing mechanism,it can reduce conflicts in dense environments.By comparison,the packet transmission success rate is increased by 17%.展开更多
Can WiFi signals be used for sensing purpose？ The growing PHY layer capabilities of WiFi has made it possible to reuse WiFi signals for both communication and sensing. Sensing via WiFi would enable remote sensing wit...Can WiFi signals be used for sensing purpose？ The growing PHY layer capabilities of WiFi has made it possible to reuse WiFi signals for both communication and sensing. Sensing via WiFi would enable remote sensing without wearable sensors, simultaneous perception and data transmission without extra communication infrastructure, and contactless sensing in privacy-preserving mode. Due to the popularity of WiFi devices and the ubiquitous deployment of WiFi networks, WiFi-based sensing networks, if fully connected, would potentially rank as one of the world＇s largest wireless sensor networks. Yet the concept of wireless and sensorless sensing is not the simple combination of WiFi and radar. It seeks breakthroughs from dedicated radar systems, and aims to balance between low cost and high accuracy, to meet the rising demand for pervasive environment perception in everyday life. Despite increasing research interest, wireless sensing is still in its infancy. Through introductions on basic principles and working prototypes, we review the feasibilities and limitations of wireless, sensorless, and contactless sensing via WiFi. We envision this article as a brief primer on wireless sensing for interested readers to explore this open and largely unexplored field and create next-generation wireless and mobile computing applications.展开更多
基金supported by National Key R&D Program of China(2018YFB1800302)Natural Science Foundation of China(61702013)+1 种基金Beijing Natural Science Foundation(KZ201810009011)Science and Technology Innovation Project of North China University of Technology(19XN108).
文摘Low-power wide area network(LPWAN)has developed rapidly in recent years and is widely used in various Internet of Things(IoT)services.In order to reduce cost and power consumption,wide coverage,LPWAN tends to use simple channel access control protocols,such as the Aloha protocol.This protocol is simple with poor extension capability.In high-density environment,Aloha protocol will lead to low channel utilization,prolonged access and high conflict probability.Therefore,in order to solve the above problems,we propose an enhanced channel access control mechanism based on the existing LoRaWAN protocol,that is,a dynamic listening backoff mechanism.We combine the improved“listen first and then talk”(LBT)mechanism with the current state of the channel to adaptively adjust the size of the backoff window.The theoretical analysis and simulation results show that the proposed mechanism have a better performance than the existing mechanism,it can reduce conflicts in dense environments.By comparison,the packet transmission success rate is increased by 17%.
文摘Can WiFi signals be used for sensing purpose？ The growing PHY layer capabilities of WiFi has made it possible to reuse WiFi signals for both communication and sensing. Sensing via WiFi would enable remote sensing without wearable sensors, simultaneous perception and data transmission without extra communication infrastructure, and contactless sensing in privacy-preserving mode. Due to the popularity of WiFi devices and the ubiquitous deployment of WiFi networks, WiFi-based sensing networks, if fully connected, would potentially rank as one of the world＇s largest wireless sensor networks. Yet the concept of wireless and sensorless sensing is not the simple combination of WiFi and radar. It seeks breakthroughs from dedicated radar systems, and aims to balance between low cost and high accuracy, to meet the rising demand for pervasive environment perception in everyday life. Despite increasing research interest, wireless sensing is still in its infancy. Through introductions on basic principles and working prototypes, we review the feasibilities and limitations of wireless, sensorless, and contactless sensing via WiFi. We envision this article as a brief primer on wireless sensing for interested readers to explore this open and largely unexplored field and create next-generation wireless and mobile computing applications.
