Machine-to-machine communications over an IEEE 802.16-based WiMAX network in the smart grid

A robust communication infrastructure is the touchstone of a Smart Grid that differentiates it from the conventional electrical grid by transforming it into an intelligent and adaptive energy delivery network. To cope with the rising penetration of renewable energy sources and expected widespread adoption of electric vehicles, the future Smart Grid needs to implement efficient monitoring and control technologies to improve its operational efficiency. However, legacy communication infrastructures in the existing grid are quite insufficient, if not incapable of meeting the diverse communication requirements of the Smart Grid. Being one of the two available 4G technologies in the world, the IEEE 802.16- based WiMAX (Worldwide Interoperability for Microwave Access) networks can significantly extend the reach of a Smart Grid by allowing fast and reliable communications over a wide coverage area. However, the unique characteristics of machine-to-machine (M2M) communications in the Smart Grid pose a number of interesting challenges to the conventional telecommunications networks, including WiMAX. Hence, considerable uncertainties exist about the applicability of WiMAX in a Smart Grid environment. The aim of this thesis is to offer an in-depth study of M2M communications over a WiMAX network in the Smart Grid. To fulfill this aim, it first conducts a detailed, technology agnostic review on the application characteristics and traffic requirements of several major Smart Grid applications and highlights their key communication challenges. Based on this review, it develops a range of traffic models for some key Smart Grid traffic sources, namely, smart meters, synchrophasors, and protective relays. Through a series of simulation studies, it then highlights a number of quality of service (QoS) and capacity issues that these applications may face within a conventional WiMAX network. A key observation from these studies is that the random access plane is the key bottleneck for supporting many of these M2M applications over a conventional WiMAX network. To further analyse the performance of the random access plane, this thesis develops a comprehensive analytical model that incorporates all the key features of the code division multiple access (CDMA) based random access mechanism, such as multi-user multi-code transmission, parallel code detection, and back-off and retransmissions. Through this model, it formulates a number of solutions, such as an enhanced random access scheme to detect a large number of random access codes, a differentiated random access strategy to provide QoS-aware access service to various M2M devices, and an adaptive radio resource management scheme to ensure an efficient utilisation of the random access resources. Moreover, it proposes and investigates a heterogeneous network (HetNet) architecture to reap maximum benefits from aWiMAX network by improving its coverage and allowing flexible data aggregation. Finally, it presents a number of application-specific optimisations to reduce radio resource utilisation and/or improve the performance of a WiMAX-based Smart Grid communications network. Many of the WiMAX specific analyses, results, and solutions in this thesis can be applied to other M2M applications beyond the Smart Grid. In addition, most of the traffic models developed and application-specific optimisations performed are technology agnostic; therefore, they are equally applicable to other wireless technologies, such as the 3GPP (3rd Generation Partnership Project) based LTE (Long Term Evolution).