Performance Analysis of the Ieee 802.15.4 Based Ecg Monitoring Network

The integration of biomedical sensors with wireless network technology may have great potentials in medical applications. In this paper, we investigate the use of the IEEE 802.15.4 standard in an ECG monitoring sensor network and study the effects of CSMA/CA mechanism, number of network devices, sampling rates and transmitting cycles. The performance of the network is analyzed in terms of transmission delay, end to end latency, and packet delivery rate. Both biomedical signal sampling time and transmission delay contribute to the end to end latency, but the end to end latency is mainly introduced by signal sampling time, especially for low data rate biomedical sensors. The packet delivery rate increases when the number of payload data becomes large due to high channel efficiency and packet coding efficiency, but large size packet suffers high end to end latency. In our case study, for a full size MAC packet with maximum payload size (114 bytes), the average end to end latency introduced by sampling and transmitting is about 90 ms. For time-critical applications, a payload size between 40 and 60 bytes can be a good choice, due to lower end to end latency and acceptable packet delivery rate. In the design and deployment of biomedical sensor networks in time-critical medical care applications, trade-off between end to end latency and packet delivery rate must be considered.