Guoquan Li

A lightweight method of data encryption in BANs using electrocardiogram signal

Abstract Body area network (BAN) is a key technology of solving telemedicine, where protecting security of vital signs information becomes a very important technique requirement. The traditional encryption methods are not suitable for BANs due to the complex algorithm and the large consumption. This paper proposes a new encryption method based on the QRS complex of the ECG signal, which adopts the vital signs from the BAN system to form the initial key, utilizes the LFSR (Linear Feedback Shift Register) circuit to generate the key stream, and then encrypts the data in the BANs. This new encryption method has the advantages of low energy consumption, simple hardware implementation, and dynamic key updating.

A PPG Signal De-Noising Method Based on the DTCWT and the Morphological Filtering

The pulse wave signal contains a variety of noises and has strong nonlinear and non-stationary. According to the previous wavelet transformation method, this paper proposes a PPG signal de-noising algorithm based on dual-tree complex wavelet transform (DTCWT) and morphological filtering. With the advantage of simple construction, clear mathematical implications and low computational complexity, this method overcomes the shift sensitive and the frequency aliasing in the discrete wavelet transform. The simulation results show that this algorithm could remove the power line interference and EMG interference, and the quantitative index of SNR and mean square error is superior to the traditional threshold de-noising algorithm. Therefore, the DTCWT and morphological filtering de-noising algorithm would obtain a clear pulse wave signal.

Channel models of body area networks for human motion

The channel characteristics of the body area network are important to transmission rate and transmission robustness. Current explorations mainly concern the channel characteristics in static state of the human body. In this paper, we establish human motion models of sitting to standing, walking and running postures, and calculate the path loss values in 2.4GHz for the models. The experimental results show that the path loss values vary sharply in the process of human movement, which is very helpful to determine the transmission power and design BAN sensor nodes.

A Sub-1V High-PSRR Piecewise-Linear Bandgap Reference

A piecewise-linear bandagp reference (BGR) with high power supply rejection ratio (PSRR) and low temperature coefficient is designed for analogue and mixed signal systems in this paper. By adopting LDO regulator, the designed high PSRR piecewise-linear BGR achieves well performances and has a simple architecture. Simulation results show that the PSRR of the designed piecewise-linear BGR with LDO regulator at 10Hz, 1kHz and 100kHz achieves, respectively, -110.42dB, -109.18dB and -64.51dB. Compared to the designed BGR without LDO regulator, the PSRR of the designed high PSRR piecewise-linear BGR with LDO regulator has the improvements of about 35dB, 36.9dB and 29.28dB at 10Hz, 1kHz and 100kHz respectively. The designed piecewise-linear BGR with LDO regulator generates an output voltage of 0.68V with 1.65ppm/oC temperature coefficient in the range from -50 oC to 125 oC. The deviation of the output voltage is within 98.23μV when the power supply voltage V DD changes from 1.2V to 7V.

Indoor Positioning Algorithm Based on the Improved RSSI Distance Model

The Global Navigation Satellite System (GNSS) cannot achieve accurate positioning and navigation in the indoor environment. Therefore, efficient indoor positioning technology has become a very active research topic. Bluetooth beacon positioning is one of the most widely used technologies. Because of the time-varying characteristics of the Bluetooth received signal strength indication (RSSI), traditional positioning algorithms have large ranging errors because they use fixed path loss models. In this paper, we propose an RSSI real-time correction method based on Bluetooth gateway which is used to detect the RSSI fluctuations of surrounding Bluetooth nodes and upload them to the cloud server. The terminal to be located collects the RSSIs of surrounding Bluetooth nodes, and then adjusts them by the RSSI fluctuation information stored on the server in real-time. The adjusted RSSIs can be used for calculation and achieve smaller positioning error. Moreover, it is difficult to accurately fit the RSSI distance model with the logarithmic distance loss model due to the complex electromagnetic environment in the room. Therefore, the back propagation neural network optimized by particle swarm optimization (PSO-BPNN) is used to train the RSSI distance model to reduce the positioning error. The experiment shows that the proposed method has better positioning accuracy than the traditional method.

A Device Based on Adaptive Filtering Algorithm for detecting ECG Signal in Motion Artifacts

Since the detection of electrocardiogram (ECG) is significant for monitoring the stress and diseases of Policeman and current methods for monitoring ECG in motion have drawback of low accuracy, a system for monitoring ECG signal is presented within this paper. The conductive silica gel is used as the collecting electrode, and a low-power-consumption device for detecting ECG signal have been designed. The movement of human body is sensed by the three-axis acceleration sensor, and variable step-size least mean square adaptive algorithm is proposed by using acceleration signal as reference signal. Through adaptive filter and real-time examining R waves of the ECG signal, heart rate is measured in the movement of human body. The results indicate that detection device can output real-time ECG signal and the maximum error of heart rate is within 4%, thus real-time performance and high accuracy of monitoring ECG signal is implemented.

A Protocol with Self-adaptive Guard Band for Body Area Networks

Body area networks (BANs) are systems of wearable computing devices for long-term monitoring of personal health care. BAN is an emerging technology for the worldwide ageing population. In the BAN system, the transceiver is the most energy-consuming part of a sensor node and radio transmission in the vicinity of the human body is highly lossy and inefficient. Therefore, the energy of the sensor node constraints the life cycle and quality of service of the network; consequently, low-cost protocol shaves attracted wide interest. This study proposes a frame structure model of a self-adaptive guard band protocol, which introduces a GB in each time slot according to the allowed maximum time drift of the crystal, adaptively adjusts the value of the GB based on the actual time drift, and then ensures that the node simultaneously maintains the sleeping state and synchronisation with the coordinator during beacon transmission, thus reducing the energy consumption.

Performance analysis for low-complexity detection of MIMO V2V communication systems

Abstract In Vehicle-to-Vehicle (V2V) communication, the rapid movement of vehicles brings fast attenuation of signal propagation and serious shift effect of Doppler frequency, leading to serious transmission performance deterioration. Multiple-Input Multiple-Output (MIMO) technique can be well applied in V2V communication by exploiting diversity and multiplexing gain to improve the system reliability and increase the data rate. In an MIMO system, the achieved diversity and multiplexing gain is closely related to its detection method. Integer-Forcing (IF) detection is one of the linear detections proposed in recent years. Compared to the traditional linear and Maximum Likelihood (ML) detection, IF has a good tradeoff between the complexity and system performance. In this paper, considering its good detection performance, IF is applied to the detection of a MIMO V2V communication system and the performance is further analyzed theoretically by employing Alamouti code at the transmitters. The diversity gain proves to be full and is confirmed by the simulation results.

Integer-Forcing Detection of Generalized Spatial Modulation

Generalized spatial modulation (GSM) activates more transmit antennas than spatial modulation to increase the spectral efficiency. Although the maximum likelihood (ML) detector is able to achieve the optimal performance, its exhaustive search leads to intractable computational complexity. In this paper, we design a detection scheme based on Integer-Forcing (IF) algorithm, which utilize IF receiver to decode the transmitted symbols for all possible antenna combinations, and then compare the Euclidean distances between the detected symbols and the received signals. Finally, the symbol vector with minimum Euclidean distance and the corresponding antenna combination are detected as the decided symbols and transmit antenna combination. Simulation results shows that the designed detection scheme achieves obviously better performance than the ZF and the MMSE detection with relatively lower complexity.

The Dynamic Encryption Method Based on ECG Characteristic Value

Body area network (BAN) is a key technology of solving remote medical, where protecting security of vital signs information is a very important technique requirement. This paper presents a data security scheme based on ECG characteristics, investigating methods of the circuit-level data encryption and dynamic key refreshment due to the obtained ECG signal characteristic value. The proposed scheme is constructed from the inherent features of the BAN system, adopting vital information from security protection, which has advantages of high strength, low cost, and easy implementation. Therefore, the scheme helps to design low-power sensor nodes and provides theoretical support and engineering implementation.