Control Mechanisms for Heterogeneous Wireless Ad Hoc and Sensor Networks

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Wireless communication in urban environments is significantly hampered by interference from external sources and from co-located networks. In radio wireless networks, access to the shared physical transmission medium must be arbitrated. This accounts for significant delay and loss of throughput even when the nodes follow the same medium access control protocol. It is much more difficult to deal with interference that is external (for example, from electronic devices) or from other networks with different medium access protocols. With the advent of the Internet of Things (IoT) this problem will escalate significantly. Mobility adds another dimension to the problem by creating a non-uniform distribution of mobile nodes that can lead to more contention. I propose a research program to design adaptive network control mechanisms to enable and improve communication over wireless networks. ******My first research direction is to develop control mechanisms to enable effective communication in the presence of interference. We will investigate the nature of external interference by collecting and analysing real samples (traces) using software-defined radios. This knowledge will be used to design and evaluate network control mechanisms. We will investigate the best combination of centralized versus distributed control over different time-frames. Next, we will experiment with software-defined radios to investigate the problem of how nodes can identify different types of networks. We will develop strategies to dynamically adjust different medium access control parameters to adapt to the channel conditions. Adding flow control mechanisms to multi-hop networks with multi-packet reception will further improve throughput. Cloud-based systems will be used to bring interference information of a larger set of nodes together, allowing us to identify fairness issues and adapt to changing network conditions. Interference is increasingly an issue in communication and therefore, understanding its nature and developing adaptive control mechanisms is important for wireless applications.******The second research direction considers the problem of mobility in wireless ad hoc networks and its effect on access to resources. Like interference, this creates heterogeneity in the access to network resources. For example, mobile nodes that rely on batteries, may move towards charging stations to renew their batteries creating opportunities for communication but also congestion in access to the wireless network. Recent advances in energy harvesting and wireless energy transfer open up new opportunities to design self-sustaining networks, but control mechanisms are required to fulfill that promise. Therefore the second research direction is to design control mechanisms that exploit these capabilities and enable applications to adapt to the variability of energy sources in mobile ad hoc wireless networks.