Research Of Physical Layer Key Techniques For Low Power Wide Coverage Networks

Low power wide area networks usually need devices to work durably and stably using battery as main power. It can be applied to monitoring for environments, agricultures, constructions and other infrastructures. Aiming at such requirement, IEEE 802.15.4k drafted standard was initialized, that was evolved from IEEE 802.15.4 standard for low-rate wireless personal area networks. As a supplement to the original standard, IEEE 802.15.4k standard provides specific advice on signal coding and modulation in physical layer and access mechanism in media access control layer.This thesis reviews the IEEE 802.15.4k standard, including data format, channel coding, interleaving, spectrum spreading and other key technologies. Since there are no commercial products or integrated chips based on this standard, the prototype of end device is designed and developed using micro controller and radio frequency module. Using the so-called Software Defined Radio (SDR) platform, this thesis conducts field test in urban environment to verify the satisfaction for standard. In order to improve the flexibility of end device, this thesis designs a pooling mechanism which uses mobile portable terminal as supplemental device to adjust the parameters of nearby end devices dynamically and remotely. With the aid of this mechanism, end device can not only enter into sleeping mode automatically but also response to parameter configuration message from supplemental device with short-time delay. Some applications are also explored based on low power wide area network, i.e., parking state detector and location-aware equipment based on GPS. In order to ensure the end device working under the supply of battery power for a long time, low power mechanism is designed for specific applications. According to the test data for power consumption, an estimation for the battery life of device is given.The contributions of this thesis mainly include the following respects:a software-defined radio platform is established based on IEEE 802.15.4k standard, and the network characteristics of wide area is confirmed. Considering the characteristics of low throughout and medium-intensity delay, SDR technology is applied to micro-controller and the software is deeply optimized for the micro controller, and the bottleneck of storage and computation speed is skillfully solved. Low power wide area networks are applied to Internet of Things, and the characteristics of low power consumption is confirmed.