A Framework for Ipv6 Based Energy Efficient Routing In Iot With Low Power Lossy Network And Multimodal Sensors

Abstract

With the advancement in semiconductor technology, a variety of low-end devices armed with different types of sensors are making their way into the market. These devices sense the environment, are capable of connecting to a network and ex- change data to support decision making systems. Most of these devices have energy, bandwidth and compute limitations. Given the scale of such devices being deployed, there is a need for a technology that can connect them to the network. The IEEE 802.15.3 standard defines operations for high-rate (11 to 55 Mbit/s) WPANs. Devices running this standard generally operate on an external power source or have large batteries. It does not work well for devices that do not have high data rates and work on small batteries with limited power source. The IEEE 802.15.4 is the standard that defines the operation of a low-rate wireless personal area network (LR-WPAN) at the physical layer. LR-WPAN is targeted for low power, low bandwidth devices (20 to 250 Kbit/s) vs. WiFi which offers more bandwidth but has higher power requirements. Given the need is to connect the devices to the Internet, the standard used at the network layer plays a major role. The Internet Protocol (IP) which is the backbone of the Internet is the obvious choice for the network layer. The predominant version of IP used in the networks today is IPv4. But IPv4 has a limited address space that does not fit well to connect millions and billions of IoT devices to the Internet. IPv6 on the other hand with a much larger address space is better suited for the needs of IoT. But the IP cannot be used directly for IEEE 802.15.4 based networks. To bridge the WPAN and IP based networks, the IETF group defined a new standard for IPv6 over Low-Power Wireless Personal Area Networks (6LoWPAN) in RFC 6282. 6LoWPAN includes encapsulation and header compression mecha- nisms that allow IPv6 packets to be sent and received over IEEE 802.15.4 based networks. 6LoWPAN operates in a layer between the data-link and network layer called the adaptation layer. In addition to the new adaptation layer, the IETF defines a new routing protocol called IPv6 routing protocol for low-power and ilossy networks (RPL) specifically for low power lossy networks (LLN). RPL is a distance-vector routing protocol that fulfills the requirements of a wide range of LLN applications. With the growth in semiconductor technology, more and more low cost de- vices are arriving in the market supporting sensors such as audio, image and video but with limited energy capacity. The focus of most research in the area of LLN has been using sensor networks that operate on scalar data such as temperature, pressure, humidity etc. Scalar sensor networks have lower bandwidth and energy requirements. While the current design paradigms of 6LoWPAN and RPL work well for scalar data, it does not perform well for sensor network with multimodal data such as audio, image, video etc. The primary focus of this research is on improving the performance of 6LoWPAN and RPL for multimodal sensor net- works. Only one multimodal data type image is chosen for performance analysis and comparison with existing implementations. The focus of this research is split into multiple areas. The first area of fo- cus is on improving the parent selection algorithm for RPL that functions better for multimodal sensors. The current parent selection algorithms in RPL do not operate well for multimodal sensors that have different properties in the areas of packet delivery ratio, energy consumption, and latency. The next area of the research defines a new IPv6 address compression schemes to reduce the overhead of the network layer in a LLN and enable more application data to be encoded in a single 802.15.4 frame. Given the size of a 802.15.4 frame is very limited, it is very important to ensure the network overhead is minimal to increase the percentage of application data that can be transmitted in a single frame. The research then defines a new weight based ranking scheme in RPL to lower the packet drops and re-transmissions in heterogeneous sensor networks (ones with both scalar and multimodal sensor nodes) by accounting the energy and data-rate requirements for individual nodes and also the link quality between nodes and assigning suitable weights to each. This helps reduce the number of re-transmissions in the network while also increasing the total network lifetime. Another area of focus of this research is to define a new multicast group man- agement scheme in RPL to optimize the multicast traffic in a LLN. Multicast traffic is important in IoT deployments and improving network efficiency to distribute such traffic is very important. All the proposals in this research is implemented in the Contiki-OS and a comparison of the performance of the same against the current RPL implementation is documented by running tests on Cooja and in theFiT-IoT lab.