PhD Thesis Completion Seminar
Wireless Body Area Networks: Efficient Coexistence by Interference Management and Avoidance
Recent advancements in wireless communications, microelectromechanical systems (MEMS) and integrated circuits have enabled low-power, intelligent, miniaturized sensors strategically placed in, on, or around, the human body. Networks of these sensors are called wireless body area networks (WBANs). One key use for WBANs is health monitoring, so they transport mission-critical and delay-sensitive data. Thus, a reliable WBAN needs to be highly immune to interference. Based on the IEEE 802.15.6 standard devised for WBANs, nodes in a single WBAN can avoid interference by using techniques such as time division multiple access (TDMA). However, these networks social nature and high mobility imply the need for multiple WBANs coexistence; so with their mobility, it is generally not feasible to allocate a global coordinator to enable coexistence. Moreover, with an increase in the number of WBANs that coexist within close proximity, communications can be severely degraded.
Thus, the primary goal of this dissertation is to devise new intelligent radio spectrum allocation strategies not only to avoid interference, but also to make best-use of limited available spectrum for reliable communication in large-scale deployments. First, we introduce an adaptive and partially orthogonal scheme called Smart Spectrum Allocation (SCA), which allows for synchronous and parallel transmissions from nodes in coexisting networks. This allows the practical coexistence of these networks giving far less communications delay, higher throughput and less interference.
A node's traffic priority, packet length, received signal strength along with density of sensors within a WBAN are further incorporated in the SCA protocol to comply with real-world variations in data type and length. We later deploy an energy harvesting module for sensor radios in these networks and use the radio interference as an energy source. To better optimize resource allocation, a hybrid scheme incorporating graph-coloring with pair-wise clustering of coexisting WBANs is proposed.
Next, in order to incorporate variations in channel assignment, based on body-dynamics mobility within each individual WBAN and amongst WBANs, a prediction algorithm is proposed to feed in these dynamics and accordingly update resource allocation. This proposal maximises the resource usage and transmission rate as well as offering a convenient trade-off between spectral reuse, transmission range and outage probability. Simulations and detailed analysis verify that the proposed approach is robust to changing channel conditions, increase in sensor node-density within each WBAN, and an increase in the number of coexisting WBANs.
Finally, we propose a self-organization scheme for the coexistence of multiple WBANs, which is biologically inspired from the theory of pulse-coupled oscillators. This approach achieves distributed management of the available spectrum amongst coexisting WBANs, and avoids the need for global management. It allows coexisting WBANs to use delayed information from previous transmissions to adjust a collision-free TDMA schedule, avoiding interference across WBANs, for future transmissions. Simulation results show that our protocol achieves rapid convergence to an updated spectrum allocation for higher packet delivery ratio, despite very-limited shared information from coexisting networks, implying that overhead is significantly reduced on WBANs with constrained resources.
Samaneh Movassaghi received a B.Sc. from University of Tehran in 2009 and a Master by Research in Telecommunication Engineering from the University of Technology, Sydney in 2012. She is currently a PhD student at the Australian National University (ANU) and is conducting research in the field of Wireless Body Area Networks. She has authored over 20 research articles with over 760 citations in her research [h-index=10] . Samaneh was recently recognized for cutting edge research on wearable networks (wearables). She was awarded as ICT Student of the year at the Australian Computer Society (ACS) Digital Disruptor Awards. She was recently awarded a Google Fellowship in Networking for her PhD reserach. Samaneh is selected as one of the seven researchers across Australia’s leading research organizations, CSIRO and NICTA, featured as the CSIROseven campaign (http://seven.csiro.au/Samaneh). Such selection was made on a basis of Samaneh’s excellent research outcomes in wearable technology. Samaneh won the 2015 NASSCOM Student Innovation Award for IT-enabled Business Innovation. This award recognizes excellence in the field of Information Technology, which particularly promotes technical innovation and is awarded to one person Australia-wide per year. She has been recently interviewed by various media specifically, SBS and ACS and featured in more than 15 newspapers and magazines Australia-wide, some of which are as follows: The Herald Sun newspaper, Sydney Telegraph, The Australian newspaper, Sunday Style’ magazine, WHO magazine , The Deal, The Australian, In the Black, Virgin – Voyeur, Vice, The Australian Financial Review, etc. Samaneh has also been providing consulting advice for a number of start-ups in e-health.