Efficient message encoding method for personal health device monitoring system

Recently, the use of personal health devices (PHDs) has greatly increased. A PHD is a device that measures, collects, and analyzes the user's biometric (medical) data. In a scenario where multiple PHDs of various types are being used, device management (DM) for PHDs is a very important issue. Meanwhile, the Open Mobile Alliance (OMA) DM protocol, which uses extensible markup language (XML) for DM messages, has been proposed as an international standard for mobile DM. Because of the expansibility and platform independency of this protocol, it has found widespread application in various management/monitoring systems for software, networks, PHDs, etc. However, XML messages typically tend to be considerably larger than the amount of actual data, which causes transmission efficiency problems, especially in PHD monitoring system. To solve the problems, a new encoding method called modified run-length encoding (MRLE) is proposed in this paper. The MRLE is described as follows. First, an XML DM message is modified by applying an XOR operation to the previously transmitted and the in-transmission XML DM messages. This causes a majority of the modified DM message to become zero. Second, the original RLE is applied to the modified DM message before transmission. This significantly reduces the size of the modified DM message because it contains a number of zeros. To verify the proposed method, we implement the method in a pulse oximeter monitoring system based on the OMA DM protocol. Next, we compare the performance of the proposed method with that of XML, WBXML and the original RLE in terms of their compression ratios and times. The results of the experiments indicate that the compression ratio of the MRLE is evidently superior to those of the compared methods and that the compression/decompression times of the MRLE is similar to that of the original RLE. Therefore, the proposed method in this paper is not only simple and easy but also highly effective for mobile DM message transmission.