A Scalable ECG Identification System Based on Locality-Sensitive Hashing.

Electrocardiograms (ECGs) have the inherent property of being intrinsic and dynamic and are shown to be unique among individuals, making them promising as a biometric trait. Although many ECG biometric recognition approaches have demonstrated accurate recognition results in small enrollment sets, they can suffer from performance degradation when many subjects are enrolled. This study proposes an ECG biometric identification system based on locality-sensitive hashing (LSH) that can accommodate a large number of registrants while maintaining satisfactory identification accuracy. By incorporating the concept of LSH, the identity of an unknown subject can be recognized without performing vector comparisons for all registered subjects. Moreover, a kernel density estimator-based method is used to exclude unregistered subjects. The ECGs of 285 subjects from the PTB dataset were used to evaluate the proposed scheme's performance. Experimental results demonstrated an IR and EER of 99% and 4%, respectively, when Nen/Nid = 15/3.

A Scalable Open-Set ECG Identification System Based on Compressed CNNs.

Deep learning (DL) is known for its excellence in feature learning and its ability to deliver high-accuracy results. Its application to ECG biometric recognition has received increasing interest but is also accompanied by several deficiencies. In this study, we focus on applying DL, especially convolutional neural networks (CNNs), to ECG biometric identification to address these deficiencies. Using prestored user-specific feature vectors, the proposed scheme can exclude unregistered subjects to realize "open-set" identification. With the help of its scalable structure and "transfer learning," new subjects can be enrolled in an existing system without the need for storing the ECGs of those previously enrolled. Finally, schemes based on the quantum evolutionary algorithm (QEA) are presented to prune unnecessary filters in the proposed CNN model. The performance of the proposed scheme was evaluated using the ECGs of 285 subjects from the PTB dataset. The experimental results demonstrate an identification rate of more than 99% in closed-set identification. Although incorporating the proposed method for unregistered subject exclusion degraded the identification performance slightly, the ability of the approach to resist a dictionary attack was evident. Finally, using the QEA-based filter pruning method and its two-stage extension reduced the number of floating-point operations required to complete one identity recognition to 1.20% and 0.22% of the original value without significantly impacting the identification accuracy.

ECG-based Biometric Recognition without QRS Segmentation: A Deep Learning-Based Approach.

Electrocardiogram (ECG)-based identification systems have been widely studied in the literature. Usually, an ECG trace needs to be segmented according to the detected R peaks to enable feature extraction from the ECGs of duration equal to nearly one cardiac cycle. Beat averaging should also be applied to reduce the influence of inter-beat variation on the extracted features and identification accuracy. Either detecting R peaks or collecting extra heartbeats for averaging will inevitably lead to a delay in the identification process. This paper proposes a deep learning-based ECG biometric identification scheme that allows identity recognition using a random ECG segment without needing R-peak detection and beat averaging. Moreover, the problem of being vulnerable to unregistered subjects in an identification system is also addressed. Experimental results demonstrated that an identification rate of 99.1% for an identification system having 235 enrollees with an equal error rate of 8.08% was achieved.