Cheong Boon Soh

Cooperative Communications in Ultra-Wideband Wireless Body Area Networks: Channel Modeling and System Diversity Analysis

In this paper, we explore the application of cooperative communications in ultra-wideband (UWB) wireless body area networks (BANs), where a group of on-body devices may collaborate together to communicate with other groups of on-body equipment. Firstly, time-domain UWB channel measurements are presented to characterize the body-centric multipath channel and to facilitate the diversity analysis in a cooperative BAN (CoBAN). We focus on the system deployment scenario when the human subject is in the sitting posture. Important channel parameters such as the pathloss, power variation, power delay profile (PDP), and effective received power (ERP) crosscorrelation are investigated and statistically analyzed. Provided with the model preliminaries, a detailed analysis on the diversity level in a CoBAN is provided. Specifically, an intuitive measure is proposed to quantify the diversity gains in a single-hop cooperative network, which is defined as the number of independent multipaths that can be averaged over to detect symbols. As this measure provides the largest number of redundant copies of transmitted information through the body-centric channel, it can be used as a benchmark to access the performance bound of various diversity-based cooperative schemes in futuristic body sensor systems.

Opportunistic routing for body area network

Wireless body area network (WBAN) is an interesting application of sensor networks which can revolutionize our interaction with the outside world. WBAN like any other sensor network suffers limited energy resources and hence preserving the energy of the nodes is of great importance. Unlike typical sensor networks WBANs have few and dissimilar sensors. In addition, the body medium has its own propagation characteristic which means that the existing solution for preserving energy in wireless sensor networks might not be efficient in WBANs. The quality of the links between the nodes in WBAN is changing frequently due to the moving nature of the body. This can pose a major problem especially in the energy efficiency merit. In this work we have proposed an opportunistic scheme to exploit the body movements during the walking to increase the life time of the network. The results show that comparing to the existing methods this work can increase the life time of the network.

Pulse Design for Time Reversal Method as Applied to Ultrawideband Microwave Breast Cancer Detection: A Two-Dimensional Analysis

We conduct a two-dimensional study of pulse design for electromagnetic time-reversal (TR) imaging as applied to ultrawideband (UWB) breast cancer detection. We consider the situation when a tumor located in the human breast is surrounded by a large number of small tissue inhomogeneities that create strong signal clutter. When applying the TR algorithm, the excitation pulse should be properly designed such that there are distinguishable differences between the tumor and clutter responses. In this paper, we propose four pulse design criteria for the TR-based tumor detection. The modulated and modified Hermite polynomials (MMHPs) that fit well into the real pulse shapes are used as a general waveform template for the design process. Finally, numerical examples are used to demonstrate the usefulness of the proposed analytical framework. This paper can be a guide in the selection of suitable waveforms for which the tumor response can be enhanced and/or the clutter interference can be suppressed. The investigation is also well suited for applications to surface-penetrating radar using UWB signals

UWB Microwave Imaging for Breast Cancer Detection --- Experiments with Heterogeneous Breast Phantoms

The paper describes pulse-based ultra-wideband (UWB) radar microwave imaging experiments for breast cancer detection using breast phantoms with dielectric properties mimicking the human breast. Three homogeneous and seven heterogeneous breast phantoms are designed with a series of dielectric permittivity and variability and are used in tumor detection experiments. The experiments are conducted in time-domain with pulse generator and real-time oscilloscope.

HOMOGENEOUS AND HETEROGENEOUS BREAST PHANTOMS FOR ULTRA-WIDEBAND MICROWAVE IMAGING APPLICATIONS

The paper discusses fabrication of homogenous and heterogeneous breast phantoms to simulate the dielectric properties of human breast over the microwave frequency range from 0.5GHz to 13.5GHz. The breast phantoms have stable mechanical conflguration and dielectric properties suitable for microwave imaging experiments particularly ultra-wideband microwave imaging for breast cancer detection.

A Hybrid Mobile-based Patient Location Tracking System for Personal Healthcare Applications

In the next generation of Infocommunications, mobile Internet-enabled devices and third generation mobile communication networks have become reality, location based services (LBS) are expected to be a major area of growth. Providing information, content and services through positioning technologies forms the platform for new services for users and developers, as well as creating new revenue channels for service providers. These crucial advances in location based services have opened up new opportunities in real time patient tracking for personal healthcare applications. In this paper, a hybrid mobile-based location technique using the global positioning system (GPS) and cellular mobile network infrastructure is employed to provide the location tracking capability. This function will be integrated into the patient location tracking system (PLTS) to assist caregivers or family members in locating patients such as elderly or dependents when required, especially in emergencies. The capability of this PLTS is demonstrated through a series of location detection tests conducted over different operating conditions. Although the model is at its initial stage of development, it has shown relatively good accuracy for position tracking and potential of using integrated wireless technology to enhance the existing personal healthcare communication system through location based services

Frequency Domain Skin Artifact Removal Method for Ultra-Wideband Breast Cancer Detection

Using ultra-wide band (UWB) microwave pulse for breast cancer detection has been greatly investigated recently since it does not expose the patient to any harmful radiation and the implementation is relatively cheaper than other methods such as MRI or X-ray. An issue in UWB imaging of breast cancer is the strong backscatter from the breast skin which is in orders of magnitude larger than the pulse backscattered from the tumor and should be eliminated before processing the signal for the tumor detection and imaging. At present no existing method can efiectively remove this artifact without introducing corruption to the tumor signature. In this paper, a novel method to eliminate this artifact is proposed which employs a frequency domain model to isolate and remove skin related information from the signal. This method is compared with the existing methods of the skin artifact removal in difierent scenarios. The results show that the new method can overcome the shortcomings of the previous methods and improve the detection of the tumor in the sense of the tumor to clutter response ratio.

A PDA-Based ECG Beat Detector for Home Cardiac Care

Recent rapid growth in mobile computing technologies enables telemedicine applications to operate on mobile devices. Our focus is on the design of an integrated electrocardiogram (ECG) beat detector on a personal digital assistant (PDA) platform for the health screening process. The ECG beat detector module will be supported by the PDA version of personal health information management system (PHIMS) and facilitated accurate referral management system (FARMS) through wireless network infrastructure as a home-based mobile cardiac monitoring solution

Time-Reversal Ultrawideband Breast Imaging: Pulse Design Criteria Considering Multiple Tumors With Unknown Tissue Properties

Pulse design is investigated for time-reversal (TR) imaging as applied to ultrawideband (UWB) breast cancer detection. Earlier it has been shown that a suitably-designed UWB pulse may help to improve imaging performance for a single-tumor breast phantom with predetermined lesion properties. The current work considers the following more general and practical situations: presence of multiple malignancies with unknown tumor size and dielectric properties. Four pulse selection criteria are proposed with each focusing on one of the following aspects: eliminating signal clutter generated by tissue inhomogeneities, canceling mutual interference among tumors, improving image resolution, and suppressing artifacts created by sidelobe of the target response. By applying the proposed criteria, the shape parameters of UWB waveforms with desirable characteristics are identified through search of all the possible pulses. Simulation example using a numerical breast phantom, comprised of two tumors and structured clutter distribution, demonstrates the effectiveness of the proposed approach. Specifically, a tradeoff between the image resolution and signal-to-clutter contrast (SCC) is observed in terms of selection of the excitation waveforms.

A note on the q-ary image of a q/sup m/-ary repeated-root cyclic code

For (n,q)=p/sup s/, where p=ch(F/sub q/), s/spl ges/1, V a q/sup m/-ary repeated-root cyclic code of length n with generator polynomial g(x), we give a partial answer about whether the q-ary image of V is cyclic or not with respect to a certain basis for F/sub q/m over F/sub q/.