Research And Implementation Of Key Technologies For Wide-area Coverage Wireless Transmission

In recent years, the Internet of Things (IoT) is increasingly popular with the public.Traditional wireless transmission technology plays an irreplaceable role in LAN applications such as smart home, industrial data acquisition and so on. However, with the explosive growth of emerging applications such as industrial monitoring, public safety, urban management, and intelligent transportation, hundreds of millions of physical network devices will be connected to wireless networks. These traditional wireless transmission technologies'coverage is small, and can not meet the massive terminal connection requirements. Therefore,in order to meet more and more low-power long-distance mass Internet of Things connected devices requirements, low-power wide area coverage wireless network comes into being.Based on the IEEE 802.15.4k protocol, the key technology of wide area coverage wireless transmission is researched and implemented. In order to achieve this goal, this paper first studies the current status of IoT, and gives a list of the shortcomings of existing wireless transmission technologies, then points out the necessity of wide area coverage wireless transmission technology,and introduces the characteristics of wide area coverage wireless transmission technology in detail. Then this paper studies the existing wide area coverage of wireless transmission key technologies, such as LoRa and NB-IoT technology. The commonly used physical layer key technologies and network key technologies are studied and summarized. Then the scheme of wide area coverage wireless transmission using direct sequence spread spectrum, star network topology and ALOHA channel access technology is proposed. Besides, the network architecture and the data frame structure of the physical layer are described in detail, and the principle and implementation of the key channel coding techniques such as convolutional forward error correction coding, interleaving coding and direct sequence spread spectrum are one by one introduced. What's more, the design goal and the system structure as well as the workflow of the transmitter based on the embedded platform are described in detail. The design objectives and implementation principles of the software-defined radio receiver are described in detail, the workflow of which is introduced from the aspects of non-coherent demodulation, preamble detection and channel decoding,and CRC check. At the end of the paper,the key technologies of wide area coverage wireless transmission are tested in different scenarios to verify the reliability and stability of the wireless transmission. The key technologies of wireless transmission are basically in line with the needs of low power wide area coverage wireless networks.The main contributions of this paper are as follows: The key technology of physical layer are researched, which is suitable for wide area coverage wireless network with low power consumption. Based on the IEEE 802.15.4k protocol, the key technology of wide area coverage wireless transmission is studied and implemented. Based on the embedded and software-defined radio platform, the low-power wide-area coverage wireless network system is implemented and its application scenarios are given. The feasibility and stability of wide area coverage wireless technology are tested and analyzed in different scenarios.