UBC Theses and Dissertations
Robust wireless access in body area networks for m-health services Torabi, Narjes
Mobile healthcare offers continuous monitoring of people’s health conditions while they are doing their daily activities. This service is realized using body area networks (BAN) that facilitate ubiquitous monitoring by eliminating wires between body nodes and the system that collect health signals for diagnostics by medical practitioners. To keep a constant flow of medical data over a BAN, body nodes have to have reliable and low-delay access to the medium when they have a sample to report. In an investigation of a proper medium access control (MAC) scheme for BANs, the IEEE 802.15.4 synchronous Beacon-Enabled mode, which is recommended for low-rate wireless personal area networks, is studied. Because of a tight network synchronization requirement of the 802.15.4 MAC, which is hard to maintain in coexistence with heterogeneous networks, an interference-aware MAC for opportunistic access to the shared medium is proposed. The Centralized BAN Access Scheme (CBAS) resolves medium access contention within a BAN while protecting BAN transmissions from being interfered by coexistent networks. Feasibility of CBAS for handling pervasive monitoring and prompt medium access requirements is experimentally investigated over the unlicensed 2.4GHz band. For channel sensing in the experimental setup, the proposed dual-spectrum-sensing strategy is applied to improve robustness of channel state detection without making any assumption about technologies of detected transmissions. Regarding diverse service requirements of collocated BANs, a distributed channel selection strategy, for integration to CBAS, is proposed for quality of service (QoS) provisioning. The kth-MAB strategy establishes a QoS-aware platform over which radio resources are distributed amongst BANs proportional to their QoS levels determined by the health conditions of the respective subject. Considering body nodes’ low power transmissions and continuously changing body posture, an adaptive cross layer design is proposed to capture BAN topology dynamism in packet routing over a BAN. In collaboration with the receiver-initiated CBAS, each body node extracts local information about its connectivity with other nodes within a BAN to contribute in improvement of the network’s packet delivery. By opportunistic capturing of high quality on-body links per packet transmission, this topology-adaptive scheduling scheme improves reliability while minimizing the need for multi-hop cooperative transmissions.
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