Hind Chebbo

Reliable Body Area Networks using relays: Restricted Tree Topology

This paper focuses on mechanisms that support the reliable transfer of data for medical applications in wireless Body Area Networks (BANs), in particular for the monitoring by sensors of vital life signs. Recent studies on path-loss models for BANs show that for some scenarios a Star Topology (ST) with a direct, single link, between sensor and coordinator is insufficient. It is thus beneficial to extend the ST to a Tree Topology with a restricted number of hops using relays. In this paper we provide an overview of relevant findings before presenting our Restricted Tree Topology (RTT) design. We then present an experiment that is set up to study the performance of RTT in terms of availability of connectivity, based on Received signal strength at 2.4 GHz using wearable channel sounders with various people sleeping - sleeping has been found to be one of the most difficult scenarios, in terms of reliability, for BAN. Our simulation results show that for certain sleeping positions, RTT improves connectivity by approximately 12% for a receiver sensitivity of -95 dBm. In addition we have shown that without RTT it is not possible to meet the reliability requirement as set out by the IEEE 802.15.6 Task Group for its draft standard.

Service-domain solutions to radio interference for M2M communications and networking

The Internet of Things (IoT) will see the connection of tens of billions of objects to the Internet over the next 10 years and will lead to improvements in the quality of life for everyone. The density of all the radio-connected IoT objects will place increasing pressure on the available limited spectrum resources. These radio-connected IoT objects will, in addition, often use different radio access technologies (RATs), making service advertising and discovery as well as coordination of radio resources extremely challenging, due to the potentially vast numbers of connected devices. These problems can be addressed both by using centralised co-ordination of radio resources and by distributed intelligent devices that actively manage their own radio resource usage. This paper addresses solutions for centralised co-ordination of the wireless connected IoT devices through a new approach which relies on a shared service-level platform to provide flexible radio spectrum usage. New algorithms for interference mitigation and device co-existence are described which use device management made possible by such a platform, and avoid potential conflicts across heterogeneous systems. Under the assumption that geographically co-located devices are all using a common service platform, the centralised algorithms proposed here have the potential for more efficient solutions than existing inter-RAT interference mitigation solutions. An implementation of our algorithms using the emerging ETSI M2M standard is outlined.

Co-Operative Use of Licensed Spectrum by Unlicensed Devices: The Concept of Bandwidth Scavenging

To mitigate the spectrum depletion due to the unprecedented wireless traffic growth, FCC has freed up large amounts of UHF spectrum and made them available to license-exempt devices. The European Commission has adopted a similar stance by pledging to quot;reuse spectrum and create a single market out of itquot;. The EC has gone as far as to call the radio spectrum the quot;economic oxygenquot;. The approach whereby license-exempt (or unlicensed) devices are allowed (under certain, often very stringent, conditions) to access unused areas of the airwaves or gaps that exist in bands that have been reserved for TV broadcasts (so-called TV White Spaces), is being trialed in the US as well as the UK and the rest of Europe, with Japan preparing its own TVWS roll-out timeline. TV White Space spectrum is an attractive alternative to expensive auctioned spectrum, for applications including e.g. small cells. In this paper we discuss an evolutionary approach looking beyond the current/emerging TV White Space concepts, for which we adopt the term Bandwidth Scavenging and which has the potential to: serve Primary User (PU) systems other than DTT; enable more dynamic spectrum sharing than the TVWS systems by providing incentives for the PU systems; allow Secondary Users (SUs) to serve as relays for PU traffic. We examine co-operation between the incumbents and SUs and demonstrate the trade-offs possible using a MATLAB simulator. We then highlight some of the changes needed in existing communication systems for the observed benefits to become a reality. We additionally discuss various models of spectrum sharing and changes needed in current spectrum legislation to support the proposed approach to collaboration.