| The great success of IP networks, makes human life relies on the Internet even more. It will bring a lot of benefits that linking every ordinary object in our lives to the Internet which has many proven technologies, that is so called Internet of Things in recent years. Benefitting from the widely spread of IPv6 across the globe, low-energy wireless nodes accessing the Internet becomes possible. Due to IPv6 has a broad address space, it can allocate global unique addresses to any objects on the earth. However, there is also a pivotal problem how wireless node can access IPv6 network. Now there are three mature wireless standards-IEEE 802.11, IEEE 802.15.1 and IEEE 802.15.4. The typical applications of the three were known Wi-Fi, Bluetooth and ZigBee respectively. It has great research value that selecting a low-power and high-compatible wireless standards.A study of 6LoWPAN technology is conducted in this paper. At first, the advantages of the use of 6LoWPAN on low-energy nodes are introduced, and the problems and challenges to be faced are raised. Then a deep analysis on the key technologies is made targeted, including fragmentation and reassembling, header compression, address allocation, routing forwarding and mobility managment. According to the study of these technologies, drawing on existing protocols at the same time, a 6LoWPAN protocol stack which runs on the Contiki operating system is proposed. At last, an actual platform is built and tested, IPv6 packets are transmitted properly in the network. In the study of 6LoWPAN, findings are made as follows:1.6LoWPAN adaptation layer has been studied. Focusing on the little data frame payload of IEEE 802.15.4, fragementation reassembling and header compression are proposed. Fragmented packets using a standard format for transmission, while using a fixed format to indicate different compressions of the data packet, in order to the receiving side can correctly decompress the reassemble. Unbroken IPv6 packets can be efficiently transmitted point-to-point in 6LoWPAN through fragementation reassembling and header compression.2.6LoWPAN routing forwarding has been studied. By focusing on the MESH topology of IEEE 802.15.4, the Mesh-Under and Route-Over routing are discussed. Mesh-Under and Route-Over both have their own advantages, but given the maturity of IP routing technology, Route-Over routing is chosen in practice. Traditional IP routing protocols are complicate for resource-constrained wireless nodes. Therefore, a more suitable RPL routing forwarding protocol is introduced.3. Mobility support for 6LoWPAN has been studied. With good mobility support of IPv6, mobility management solutions which are suitable for wireless nodes are explored, including the analysis of the possibility that porting existing protocols to 6LoWPAN, such as MIPv6, HMIPv6 and PMIPv6. Also a new scheme is proposed, the mobility management to be tested on the actual system. Network mobility is discussed and a feasibility solution is proposed.4. The implementation of 6LoWPAN system has been studied. It is necessary that choosing suitable hardware and software platforms for 6LoWPAN, the system is built by using TI’s CC2538 and Swedish Institute of Computer Science’s Contiki operating system. Hardware and software platforms are the basis for the actual test and application, so the robust 6LoWPAN and uIP protocol stack code structures in Contiki are introduced.In this paper, the 6LoWPAN pivotal fragmentation reassembling, header compression, address configuration and UDP datagram transmission are verified through the 6LoWPAN technology research and implementation, so are the system building and tests. In the tests, the system achieves the desired goals, and this marks the correctness of theory research and the feasibility and effectiveness of practical system. |
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