Ilangko Balasingham

Dynamic Spectrum Allocation in Wireless Cognitive Sensor Networks: Improving Fairness and Energy Efficiency

This paper considers the centralized spectrum allocations in resource-constrained wireless sensor networks with the following goals: (1) allocate spectrum as fairly as possible, (2) utilize spectrum resource maximally, (3) reflect the priority among sensor data, and (4) reduce spectrum handoff. The problem is formulated into a multi-objective problem, where we propose a new approach to solve it using modified game theory (MGT). In addition, cooperative game theory is adopted to obtain approximated solutions for MGT in reasonable time. The results obtained from numerical experiments show that the proposed algorithm allocates spectrum bands fairly with well observing each sensors priority and nearly minimal spectrum handoffs.

Propagation models for IEEE 802.15.6 standardization of implant communication in body area networks

A body area network is a radio communication protocol for short-range, low-power, and highly reliable wireless communication for use on the surface, inside, or in the peripheral proximity of the human body. Combined with various biomedical sensors, BANs enable realtime collection and monitoring of physiological signals. Therefore, it is regarded as an important technology for the treatment and prevention of chronic diseases, and health monitoring of the elderly. The IEEE 802 LAN/MAN Standards Committee approved Task Group TG15.6 in December 2007. As a result of more than four years of effort, in February 2012, TG15.6 published the first international standard for BANs, IEEE Std 802.15.6. Throughout the development of this standard, ample collaboration between the standardization group and the research community was required. In particular, understanding the radio propagation mechanisms for BANs demanded the most research effort. Technical challenges were magnified for the case of implant communication because of the impossibility of conducting in-body measurements with human subjects. Therefore, research in this field had to make use of intricate computer simulations. This article outlines some of the research that has been done to obtain accurate propagation models supporting the standardization of implant communication in BANs. Current research to enhance the channel models of IEEE Std 802.15.6 through the use of ultra wideband signals for implantable devices along with physical measurements in animals is also presented.

Architecture of an ultra wideband wireless body area network for medical applications

The utilization of wireless technology in traditional medical services provides patients with enhanced mobility. This has a positive effect on the recovery speed of a patient after major surgical procedures or prolonged illness. This paper presents the architecture of a healthcare wireless network that exploits the capabilities of ultra wideband technology (UWB) for medical sensing and in-body tracking and imaging. The communication requirements for an UWB wireless body area network (WBAN) are enlisted. Both on-body and in-body sensors are taken into consideration. Special attention is paid to the requirements of a capsule endoscope, which is one of the most throughput-demanding sensors in modern telemedicine.

New QoS and geographical routing in wireless biomedical sensor networks

In this paper we deal with biomedical applications of wireless sensor networks, and propose a new quality of service (QoS) routing protocol. The protocol design relies on traffic diversity of these applications and ensures a differentiation routing using QoS metrics. It is based on modular and scalable approach, where the protocol operates in a distributed, localized, computation and memory efficient way. The data traffic is classified into several categories according to the required QoS metrics, where different routing metrics and techniques are accordingly suggested for each category. The protocol attempts for each packet to fulfill the required QoS metrics in a power-aware way, by locally selecting the best candidate. It employs memory and computation efficient estimators, and uses a multi-sink single-path approach to increase reliability. The main contribution of this paper is data traffic based QoS with regard to all the considered QoS metrics. To our best knowledge, this protocol is the first that makes use of the diversity in the data traffic while considering latency, reliability residual energy in the sensor nodes, and transmission power between sensor nodes as QoS metrics of the multi-objective problem. The proposed algorithm can operate with any MAC protocol, provided that it employs an ACK mechanism. Performance evaluation through a simulation study, comparing the new protocol with state-of-the QoS and localized protocols, show that it outperforms all the compared protocols.

Ultra-wideband pulse-based data communications for medical implants

Impulse radio (IR) ultra wideband (UWB) technology is assessed herein for wireless data communications with a capsule endoscope operating inside the digestive tract. The UWB channel is characterised for the frequency range of 1-5-GHz and line-of-sight (LOS) scenarios. Owing to the lack of a standardised mathematical model for in-body UWB signals, the channel characterisation is attained by using numerical simulations. Because of the lossy material properties of the human tissues, short delay spread of the in-body channel is observed. The design of a packet based IR-UWB transmitter is presented herein, considering the restrictions on power consumption, size, cost and complexity. A novel coherent receiver using a single-branch correlation scheme is proposed. The receiver system performance is optimised by adjusting the shape and the delay of the template pulse for providing maximum output of the correlator. Its bit-error-rate (BER) performance using bi-phase pulse amplitude modulation (BPAM) is evaluated. The effects of different templates on the system performance are also investigated. Fast synchronisation is achieved by using a bank of correlators; the number of correlator branches and the preamble length for successful synchronisation are estimated. This investigation reveals the feasibility of using IR-UWB for capsule endoscope fast data transmission.

Cognitive radio for medical body area networks using ultra wideband

Wearable wireless medical sensors beneficially impact the healthcare sector, and this market is experiencing rapid growth. In the United States alone, the telecommunications services market for the healthcare sector is forecast to increase from

On ultra wideband channel modeling for in-body communications

7.5 billion in 2008 to

Zero-Delay Joint Source-Channel Coding for a Bivariate Gaussian on a Gaussian MAC

11.3 billion in 2013. Medical body area networks improve the mobility of patients and medical personnel during surgery, accelerate the patients¿ recovery, and facilitate the remote monitoring of patients suffering from chronic diseases. Currently, MBANs are being introduced in unlicensed frequency bands, where the risk of mutual interference with other electronic devices can be high. Techniques developed during the evolution of cognitive radio can potentially alleviate these problems in medical communication environments. In addition, these techniques can help increase the efficiency of spectrum usage to accommodate the rapidly growing demand for wireless MBAN solutions and enhance coexistence with other collocated wireless systems. This article proposes a viable architecture of an MBAN with practical CR features based on ultra wideband radio technology. UWB signals offer many advantages to MBANs, and some features of this technology can be exploited for effective implementation of CR. We discuss the physical and MAC layer aspects of the proposal in addition to the implementation challenges.

MRL-CC: a novel cooperative communication protocol for QoS provisioning in wireless sensor networks

Innovative medical applications such as implant wireless sensors for health monitoring, automatic drug deliverance, etc. can be realized with the use of ultra wideband (UWB) radio technology. Nevertheless, for efficient design of wireless systems operating inside the human body a radio communication channel model is essential. Although a lot of research effort has recently been devoted to the characterization of the on-body UWB radio communication channel, just a few works describing the radio propagation inside the human body have been reported. To address this problem, a computational study of the propagation of UWB signals through human tissues in the 0.1-1 GHz and 1-6 GHz frequency bands is presented in this paper. This is based on numerical simulations using a heterogeneous anatomical model of the human body with frequency dependent tissue material properties. Subsequently, a statistical channel model is introduced for UWB in-body communications in the 1-6 GHz frequency band. The model is provided for two typical depths inside the human chest. This work contributes to the practical design of UWB medical implant communication systems.

A novel artificial bee colony algorithm with space contraction for unknown parameters identification and time-delays of chaotic systems

In this paper, delay-free, low complexity, joint source-channel coding (JSCC) for transmission of two correlated Gaussian memoryless sources over a Gaussian Multiple Access Channel (GMAC) is considered. The main contributions of the paper are two distributed JSCC schemes: one discrete scheme based on nested scalar quantization, and one hybrid discrete-analog scheme based on a scalar quantizer and a linear continuous mapping. The proposed schemes show promising performance which improves with increasing correlation and are robust against variations in noise level. Both schemes also exhibit a constant gap to the performance upper bound when the channel signal-to-noise ratio gets large.