Conclusions

It has been recognised within the electricity industry and the research community that a reliable and resilient communication system is one of the principal foundations of Smart Grid. Nonetheless, there is still constant deliberation on the most appropriate technology for Smart Grid deployment and the necessary adjustments to meet specifications of different applications and traffic sources (devices/nodes). In spite of the fact that wireless communication technologies have predominance over other communication technologies in this field, there exists some challenges and uncertainties. These include the network performance of the communication technologies in a M2M environment, where a vast number of emerging application traffic types with different requirements are transferred between different devices. Another important challenge is adaptability to current and future communications needs. The enormous size of the electrical grid has led to the recommendation of a hierarchical deployment of communication technologies referred to as network components of the Smart Grid by the research community.

This thesis has been particularly centred on the communication of NAN component of Smart Grid. As a potential communication technology for NAN, the IEEE 802.11 ad hoc WMN is also subjected to vulnerabilities and challenges, including selecting the most appropriate routing protocol.

The goal of this research was to identify these challenges and suggest appropriate measures that will enable improved network reliability on a NAN based IEEE 802.11 ad hoc WMN and guarantee maximum benefit for the utility operator. In particular, the thesis has validated the bottleneck and congestion issue across multi-hops in ad hoc WMN deployed in NAN, and proposed a number of solutions to this problem. Most important, it should be realised that the ad hoc WMN has no QoS support for target Smart Grid applications across multi-hops to the destination, or data concentrator in the case of NAN. In recognition of this, the thesis explored a cross-layer approach using multiple link metric routing with OLSR to enhance the reliability of routing and provide QoS support for application specific requirements across multiple hops in NAN based ad hoc WMN. The cross-layer routing approach is used because it enables protocols to make decisions that demonstrate cognisance of the resources and capabilities of intermediate nodes as well as enhance routing decision based on the type of application to be transmitted. Cross-layer routing approach is also a key requirement for the implementation of network management capabilities and QoS support for target application traffic types on routing protocols.

This chapter summarises the work presented in this thesis; it highlights the main contributions as well as associated results and conclusions from research findings. In addition, it presents a discussion on the prospective research directions and recommends future work.

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It is important to state that this research was done in collaboration with a local small and medium enterprise (SME) company. The SME sought to collaborate with utility companies to adapt novel communication techniques as well as integrate both IP and QoS into pre-existing non-IP communication systems for Smart Grid communication. The benefit of this study includes modifying the ad hoc WMN for reliable communication in the NAN segment of Smart Grid.

This study provided a background to Smart Grid communication in Chapter 2, which gave an overview of Smart Grid communication systems and key Smart Grid applications, as well as their traffic requirements and characteristics. The adaptation of ITU's USN architecture and review of available communication technologies for Smart Grid is presented. The USN architecture was recommended to provide a seamless ubiquitous coverage and interaction with all the Smart Grid traffic sources on the hierarchical communication network. The chapter also discussed Smart Grid applications and network components and suggested layers of the USN architecture to be deployed. It highlighted that a seamless heterogeneous communication for Smart Grid could only be achieved through a secure and QoS aware USN middleware system to minimise the vulnerabilities and challenges of a heterogeneous Smart grid communication network. Given that the characteristics of different existing communication technologies for Smart Grid vary; it was recommended that the choice of communication technology must depend on technical and economic factors as well as their capability to guarantee security, reliability and resilience. For this reason, a review of existing communication technologies was carried out with emphasis on technologies that can combine to form a reliable heterogeneous network for Smart Grid.

The emphasis of the study was shifted to routing in Smart Grid’s NAN, specifically the ad hoc WMN and OLSR protocol, which is the research path of the thesis. The NAN is a Smart Grid segment that will involve routing. Though other routing protocols have been proposed for this Smart Grid segment, the OLSR protocol was selected because it has good performance in large networks and it is also implemented on existing CoTs devices that will speed up experimental evaluation and research.

Chapter 3 presented a classification of Smart Grid application traffic according to their packet sizes and delay objectives. Four traffic class categories were identified representing the importance of Smart Grid traffic, namely, delay tolerant - loss tolerant class, delay tolerant - loss intolerant class, delay sensitive - loss tolerant class and delay sensitive – loss intolerant class. A performance analysis of routing capabilities of the ad hoc WMN in a NAN for AMI using traffic profiles that represent each Smart Grid application traffic class was carried out on an experimental setup and ns-3 simulation. During the simulation study, two routing protocols, IEEE 802.11s HWMP and the OLSR routing protocols were evaluated. The OLSR was compared against HWMP because it is the protocol specified for ad hoc WMN (IEEE 802.11s) standard to validate its performance. Based on the topology and parameters used in the simulation, results showed that the performance of OLSR protocol in terms of delay, PDR and

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throughput, is the same or, in some cases, marginally better than the IEEE 802.11s standard default protocol. Based on the results, a recommendation was reached to study cross-layer network management options and QoS routing in NAN for AMI using OLSR.

Based on the recommendations in Chapter 3, the possibility of using multiple metrics OLSR to support QoS routing in NAN based WMN for AMI through the use of AHP was studied in Chapter 4. During the study, two metrics - OLSR_ETX and OLSR_ML - were selected as the best performing link metrics on reliability and delay respectively. They were used along with the AHP algorithm to present a case for adaptively supporting QoS (delay and reliability) for targeted AMI application in a NAN based WMN.

Chapter 5 presented the implementation process to improve the performance of OLSR by using multiple metrics, guaranteeing best route selection for application traffic types in NAN. Results from the implementation on ns-2 showed an improvement in the reliability and delay performance of application traffic types with high QoS demands in Smart Grid NAN. The improvements were based on the AHP an MCDM technique and multiple OLSR link metrics to select routes to the data concentrator that best suits an application traffic type. This process has provided a novel method of overcoming the weaknesses of single metrics, introducing QoS routing, and supporting variable application traffic types in a NAN based ad hoc WMN.