Yangzhe Liao

Flexible quality of service model for wireless body area sensor networks

Wireless body area sensor networks (WBASNs) are becoming an increasingly significant breakthrough technology for smart healthcare systems, enabling improved clinical decision-making in daily medical care. Recently, radio frequency ultra-wideband technology has developed substantially for physiological signal monitoring due to its advantages such as low-power consumption, high transmission data rate, and miniature antenna size. Applications of future ubiquitous healthcare systems offer the prospect of collecting human vital signs, early detection of abnormal medical conditions, real-time healthcare data transmission and remote telemedicine support. However, due to the technical constraints of sensor batteries, the supply of power is a major bottleneck for healthcare system design. Moreover, medium access control (MAC) needs to support reliable transmission links that allow sensors to transmit data safely and stably. In this Letter, the authors provide a flexible quality of service model for ad hoc networks that can support fast data transmission, adaptive schedule MAC control, and energy efficient ubiquitous WBASN networks. Results show that the proposed multi-hop communication ad hoc network model can balance information packet collisions and power consumption. Additionally, wireless communications link in WBASNs can effectively overcome multi-user interference and offer high transmission data rates for healthcare systems.

An incremental relay based cooperative routing protocol for wireless in-body sensor networks

In this paper, we aim to minimize in-body sensor node energy consumption and to prolong the network lifetime by utilizing a relay strategy based on our proposed flexible quality of service (QoS) radio frequency communication module and advanced In-to-out body path loss (PL) model. A selection algorithm is derived and investigated in which the relay nodes with lower energy consumption and minimum distance to the coordinator will be chosen in each round. In this way, time division multiple access (TDMA) can be investigated to schedule data transmission from implants to the corresponding relays, and thus minimize the overall length of communication links. Moreover, a linear programming network lifetime model is proposed along with various subjective functions. Followed by constraints, simulations are conducted on a proposed topology network assuming two commercial transceivers. Results show that the existing two-relay based protocol achieves higher transmission data rates due to the availability of redundant communication pathways. However, our proposed incremental relay-based cooperative routing protocol outperforms the existing two-relay based scheme regarding total network lifetime, overall throughput, average power consumption and propagation delay.

Mutual-Information-Based Incremental Relaying Communications for Wireless Biomedical Implant Systems

Network lifetime maximization of wireless biomedical implant systems is one of the major research challenges of wireless body area networks (WBANs). In this paper, a mutual information (MI)-based incremental relaying communication protocol is presented where several on-body relay nodes and one coordinator are attached to the clothes of a patient. Firstly, a comprehensive analysis of a system model is investigated in terms of channel path loss, energy consumption, and the outage probability from the network perspective. Secondly, only when the MI value becomes smaller than the predetermined threshold is data transmission allowed. The communication path selection can be either from the implanted sensor to the on-body relay then forwards to the coordinator or from the implanted sensor to the coordinator directly, depending on the communication distance. Moreover, mathematical models of quality of service (QoS) metrics are derived along with the related subjective functions. The results show that the MI-based incremental relaying technique achieves better performance in comparison to our previous proposed protocol techniques regarding several selected performance metrics. The outcome of this paper can be applied to intra-body continuous physiological signal monitoring, artificial biofeedback-oriented WBANs, and telemedicine system design.

An In-body communication link based on 400 MHz MICS band wireless body area networks

Implant wireless body area networks (WBANs) are becoming increasingly significant for numerous applications in the healthcare and medical sectors. Here an in-body communication model is proposed, based on a 1 mm resolution mesh kneeling position inhomogeneous 30-year male body model in the 400 MHz medical implant communication service (MICS) band. Firstly, semi-empirical path loss models for numerous homogeneous tissues and a heterogeneous human body model are proposed. Then we investigate the bit error rate (BER) performance using the heterogeneous human body channel model. Coupled with link margin analysis, this model can be applied to future implementations and system design research work.

Analysis of PC and SGA models for an ultra wide-band ad-hoc network with multiple pulses

The performance of six different shapes of pulses is compared for Packet Collision (PC) and Standard Gaussian Approximation (SGA) communication systems, based on the requirements of the Federal Communications Commission (FCC) emission mask. The shapes are a second derivative sinusoid Gaussian pulse, a second order Gaussian pulse and the first four orders of modified Hermite pulses. For the SGA model, the performance of time-hopping (TH) pulse position modulation (PPM) and pulse amplitude modulation (PAM) are compared, in terms of Bit Error Rate (BER). For the PC model, we investigated pulse position modulation (PPM) to analysis the performance from the energy attenuation issue. Results show that the zero order modified Hermite pulse outperforms other pulses in terms of BER in the PC model. It is also found that the performance of both the PC and SGA models will get worse as the number of users increases. The results can be applied to deal with interference issues in wireless body area networks (WBAN) in field of remote health monitoring and telemedicine systems design.

Performance evaluation of reliable communications for wireless in-body sensor networks

Wireless in-body sensor networks are attracting increasing attention for numerous healthcare applications and medical services. Implant devices are widely employed to measure physiological signals inside the human body in a simple, long lifetime and continuous approach. However, due to the strict technical requirements of implant devices, there exist numerous key research challenges in this area. Considering realistic transmission power requirements based on the IEEE 802.15.6 standard safety regulations, the channel characteristics of implant to deep implant and implant to body surface communication scenarios are investigated. Furthermore, multiple vital quality of service (QoS) factors of implant communication channels are studied regarding channel capacity, bit error rate (BER), link quality and data rate. The system performance evaluation indicates that the data transmission rate can be optimized up to 10 Mbps. Furthermore, the transmission distance supported by in-body to on-body communication path is 2 meters, at 1 µW while the in-body to deep tissue region communication channel achieves less than 1 meter. The results proposed in this paper give an outlook of the intra-body networking system performance and can be applied to in-body communication system implementation research.