PAL: A Path Selection Algorithm for Life Critical Data

The real time data transmission facilities provided by Personal Area Networks (PAN) can improve both the life expectancy and living conditions of patients following cardiac surgery. The limited signal range of such devices however, coupled with the life critical nature of the data transferred places strict performance limits on the mobility protocol. The Stream Control Transmission Protocol (SCTP) can support mobility through its multi-homing feature. SCTP has 2 core features (1) analyzing performance metrics which trigger network migration (2) implementing the physical migration from one network path to another. We illustrate that as a transport layer protocol which adheres to protocol boundaries SCTP´s network evaluation is performance limited, as Bluetooth MAC retransmissions distort end-to-end calculations. We propose a division of functionality in which SCTP is responsible for network migration while we propose a new Path Selection Algorithm for Life Critical Data (PAL) which defines a Media Independent Handover (MIH) oriented trigger to control path switchover. PAL illustrates the importance of Bluetooth MAC retransmissions as a performance metric over traditional metrics such as Received Signal Strength (RSS).