Delay efficient emergency access control protocol in medical implant communication

In order to find out current operating channel of the hub during emergency in medical implant communication, an implant node sequentially sends an empty frame in all the available channels until it receives an acknowledgement. The channel scanning process by sending an empty frame in advance, however, adds higher overhead if the probability of transmission in the correct channel is high and/or payload size is small. In such scenario, the direct data transmission technique in which node transmits data directly without empty frame in advance could exhibit better performance. In this paper, to save emergency packet suffering from inappropriate delay, we propose to use these two transmission schemes adaptively. Nodes select their transmission mode by taking into account both the probability of successful transmission and the payload size. We find payload threshold value that serves as switching criterion between two schemes during various network conditions. Through rigorous analysis and simulation, we show that the proposed scheme significantly enhances the delay performance.