Application of near-field intra-body communication and spread spectrum technique to vital-sign monitor evaluation of error rate in ambulatory status

As a novel vital sign monitor, we have developed wireless ECG monitoring system with Near-field intra-body communication (NF-IBC) technique. However, it was hard to ensure communication reliability because transmission channel is noisy and unstable. In order to improve the problem, we utilize spread spectrum (SS), which is known as robust communication technique even through poor transmission channel. In previous study, we have already developed an ECG monitor using NF-IBC enhanced by SS. In this paper, we evaluated bit error rate (BER) of the system devices in ambulatory status of the user such like walking. The test result shows that communication reliability depends on walking speed. However, it was found that reliability was high enough for practical use. These results indicated that the wireless monitor based on SS NF-IBC was applicable to unrestrained vital-sign monitor.