The Research And Implementation Of Wireless Sensor Network Based On IPv6

Wireless Sensor Networks (WSN) consist of spatially distributed autonomous sensors to cooperatively monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants. As sensor network technology develops, connectivity between the wireless sensor network and the IP-based Internet has become an important requirement. The RFC 4944 standard defined by the IETF 6LoWPAN working group is a good example of efforts to connect WSNs with IP networks. It specifies how IPv6 is carried over a low-power wireless personal area networks (LoWPAN) such as IEEE 802.15.4 networks with the help of the adaptation layer which sits between the MAC layer and the IP network layer. The adaptation layer provides several mechanisms used for header compression, fragmentation and reassembly in link-layer, mesh routing supporting, etc. to integrate the IEEE 802.15.4 networks with the IP networks seamlessly. Based on the Internet-drafts and RFCs published by 6LoWPAN working group, this paper designs and implements the 6LoWPAN protocol in wireless sensor networks with star structure. Some tests are conducted methodically to prove the accuracy of the design and implementation.Devices within LoWPANs usually have limited display and input capabilities. Additionally, they are expected to be deployed in exceedingly large number and the location of these devices may be hard to reach. Accordingly, Stateless Address Autoconfiguration is highly desirable, which needs the assistance of Neighbor Discovery Protocol (NDP). The Neighbor Discovery Protocol is a protocol in the Internet protocol suite used with IPv6. Nevertheless, the NDP was not designed for LoWPANs since the traditional NDP makes heavy use of multicast. This makes the LoWPAN inefficient and sometimes impractical. This paper describes some optimizations to NDP for meeting the requirements of low power consumption and low resource cost in 6LoWPAN.This paper begins with the technical situation and developing trend of WSNs, then introduces the IPv6 and IEEE802.15.4 protocol, which have high correlation with 6LoWPAN. Referred to the 6LoWPAN's Internet-drafts and RFCs, its key technologies are descripted, including 6LoWPAN adaptation layer, frame format, fragmentation and reassembly, header compression, mesh router supporting, IPv6 address mapping and so on. Based on the driver of CC2420, We design and implement the 6LoWPAN protocol stack on Imote2 in a WSN with star-shaped topological structure. After that, we analyze its system framework, describe the implementation of protocol stack, then construct a testing environment and do some tests to prove the accuracy. The result of test show that the system works well, the IEEE 802.15.4 networks are integrated into the IP networks seamlessly.In this paper we proposed the optimizations to IPv6 NDP specially aimed at low-power and lossy network such as 6LoWPANs. The improvement measures for NDP consist of reducing the number of Router Solicitation and Router Advertisement through optimizing router/prefix/parameter discovery, reducing or avoiding using the address resolution, duplicate address detection and redirect, replacing neighbor unreachability detection in NDP with unreachability detection in MAC layer.Finally, it summaries the main work of this paper and gives the expectation and suggestion.