A Modified Run-Length Coding towards the Realization of a RRO-NRDPWT-Based ECG Data Compression System

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Research Article A Modified Run-Length Coding towards the Realization of a RRO-NRDPWT-Based ECG Data Compression System Hsieh-Wei Lee, King-Chu Hung, Tsung-Ching Wu, and Cheng-Tung Ku Department of Computer and Communication Engineering, National Kaohsiung First University of Science and Technology, Taiwan Correspondence should be addressed to Hsieh-Wei Lee, [email protected] Received 9 November 2010; Revised 1 March 2011; Accepted 4 March 2011 Academic Editor: Patrick Oonincx Copyright © 2011 Hsieh-Wei Lee et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The wavelet-based approach that combines a reversible round-off nonrecursive discrete periodized wavelet transform (RRONRDPWT) and the set partitioning in hierarchical trees (SPIHT) scheme is an efficient ECG data compression. However, this RRO-NRDPWT-based system suffers from the high complexity of the SPIHT scheme during realization. In this paper, a modified run-length coding (MRLC) algorithm is proposed towards the realization of a RRO-NRDPWT-based ECG data compression system. The MRLC with its regularity and low computational complexity is suitable for hardware implementation, but at a cost of compression performance. This sacrifice is compensated by an efficient quantization scheme. By using the MIT-BIH arrhythmia database, the experimental results show that the proposed scheme can compete with the SPIHT scheme for a compression ratio (CR) greater than 8. Hardware simulations are taken using both the Verilog logic simulator with Cadence design platform, and a Xilinx FPGA EP2C35F672C6.

1. Introduction An electrocardiogram (ECG) is a non-invasive modality that senses the electric action of heart motion from the surface of a body. Since the heart is a three-dimensional organ, heart disease diagnosis usually requires the use of several ECG signals sensed at various positions around the heart. A typical requirement for heart disease diagnosis and health care is a long-term record of 12-lead ECG signals [1]. To this end, portable ECG sensing systems associated with wireless data transmission have been developed for ambulatory monitoring and recording. ECG data compression is crucial for creating a reduction in power consumption, efficient data transmission, and storage [2, 3]. In many ECG data compression methods, waveletbased approaches with high compression performance have attracted much attention from researchers [4–7]. These approaches that attempt to optimize the compromise between CR and distortion all employ the lossy compression method in which the percentage root-mean-square difference (PRD) is usually used as the distortion measure. Lossy ECG data compression can be meaningful only if clinical information and reconstruction quality can be preserved and

maintained. Quality maintenance is usually time consuming due to the recursive process of compression and reconstruction error measure