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Patient Health Monitoring Using WirelessBody Area Networks

M. Arif Siddiqui1, Qazi Shoeb Ahmad1, Riyaz Ahmad Khan1 & M. H. Khan2

1Integral University, Lucknow2Institute of Engineering and Technology, Lucknow

ABSTRACT

The rapid technological developments in intelligent sensors, low power integrated circuits, and wireless networks havefacilitated the design of intelligent wearable and implantable devices for long term monitoring of physiological logicalsignals. We believe that the recent development in wireless body area networks (WBANs) promise the low cost healthcare and continuous health monitoring of patients suffering from chronic diseases such as heart disease, kidney disease,diabetes and hyper tension. In this paper, we have discussed the existing architecture of WBAN and their applications.Furthermore, we have also talked about the current research issues, challenges and future trends.

Keywords: Wireless Networks, Wireless Body Area Networks, Wearable Computing, Health Monitoring, Sensors.

* Correspondence: E-mail: arif.sid@hotmail.com,qazishoeb@rediffmail.com, riyazakhan68@yahoo.co.in,mhkhan.ietfaculty@yahoo.com

1. INTRODUCTION

According to World Health Organization (WHO) inRepublic of Korea 17% people die due to cerebrovasculardisease [1]. In United States between 44000 and 98000people die to preventable medical error by physicians[2] and the overall national’s annual medical cost isreached around $1.8 trillion in 2004 [3]. In Europe, 90%of people die due to arrhythmogenic event [4]. Irregularheart beat causes such deaths and can be monitoredbefore heart attack. Currently, holter monitor is used tocollect cardio rhythm disturbances but the system doesn’tprovide real time feedback and the ECG data is collectedfor offline processing. Transient abnormalities aresometimes hard to capture. For instance, many cardiacdiseases are associated with episodic rather thancontinuous abnormalities such as transient surges inblood pressure, paroxysmal arrhythmias or inducedepisodes of myocardial ischemia and their time cannotbe predicted [4]. In future the WBAN technology willimprove the quality of life at low cost and reduced hassleof medical professionals with the availability of vitalinformation of patients at any time and at any place.

A recent development in intelligent sensors andwireless networks are playing significant role in ourroutine lives. Though WBAN can not avoid all medicalerrors but in order to reduce the medical cost and avoidpreventable medical errors, WBANs offer the earlydetection of disease and continuous access of patient’s

vital data. Typical WABNs consist of light weight,minaturaised, low power and inexpensive sensors, eitherwearable or implanted into the human body, whichmonitors the vital physiological data of the patients suchas electrocardiogram (ECG), electromyography (EMG),blood pressure sensor, motion sensor and breathingsensor etc. [5]. The WBAN technology is just started andis hot research area world wide, and is expected to be anintegral part of healthcare solutions leading to conceptslike telemedicine and m-health [6]. This paper containsa brief overview of WBAN architecture. We havepresented various research and industrial applicationsof WBAN technology. We also talk about variousresearch issues and challenges and finally, we discussvarious possible research trends.

2. WBAN ARCHITECTURE

A health monitoring system or WBAN is a multi-tierarchitecture as shown in Figure 1. The lowest tier consistsof a set of intelligent physiological sensors eitherwearable or implanted in to human body which monitorsthe vital physiological signals and communicates withthe second level i.e. a personal server, which forwardsinformation to the medical database stations.

The lowest level is called the sensor level and consistsof physiological sensors such as electrocardiogram (ECG)for monitoring heart activity, electromyography (EMG)for monitoring muscle activity, blood pressure sensor formonitoring blood pressure, movement sensors formonitoring user’s activity, and oxygen saturation sensor(SpO2) for monitoring the level of oxygen etc. dependingon the patient’s clinical requirements. These

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physiological sensors are extremely low power whichmakes them suitable for human body [7]. Thesephysiological sensors collect the vital patient informationand transfer to a personal server through WBANtechnologies such as Bluetooth (IEEE 802.15.1) or ZigBee(IEEE 802.15.4). The personal server can be a cell phone,personal digital assistant (PDA), user’s personalcomputer, or any other intelligent node which pulltogether the patient’s vital information andcommunicates with the top level remote base station i.e.health provider’s medical server through the internet ormobile telephone networks such GPRS or 3G.

The top level of the tired architecture is consistingof remote base stations or health provider’s medicalservers. The medical server automatically collects thepatient’s data and processes them and issuesrecommendations and if necessary store them into thepatient’s medical database for future use [5]. The GPRSsystem is used to locate the exact location of patient. Themedical server also authenticates the registered users andtriggers the events to emergency care givers when serioushealth irregularity is recognized [8].

3. CURRENT RESEARCH AND APPLICATIONS

Traditionally, Holter monitors were used to collect cardiorhythm disturbances for offline processing without realtime feedback. Some other monitoring systems such asportable Holter monitors [9], simple pulse monitors [10]and activity monitors [11] have been developed.

However, these traditional systems are unsuitable forambulatory health monitoring. The sphymacor andportapress system are installed in laboratories andhospitals for hypertensive study. Both methods provideinvalid information of arterial health and don’t reflectany form of arrhythmias [12].

A CodeBlue project at Harvard University hasdeveloped various hardware platforms such as Wirelesspulse oximeter sensor, EMG sensor for stroke patientmonitoring shown in Figure 2 and 3 and developingvarious software application for wireless medicalservices [13]. A project called Connect focuses on thedevelopment of a distributed wireless communicationinfrastructure to customize wireless devices of disabledpeople for communicating with their health serviceprovider [14]. A project called MobiHealth hasdeveloped a wearable monitoring system for healthmonitoring of patients in tandem allowing them to freelymove and hound their daily life activity [15]. The aim isto develop a fast and reliable system in case of accidentsto send audio and video data continuously to the healthcare centre from the accidents’ site.

Recently many researchers concentrate on powerconsumption issue for body area network. The existingWBAN architecture including BSN node uses IEEE802.15.4 (Zigbee) wireless link as a low powercommunication protocol. But the narrowbandimplementation doesn’t satisfy the energy consumptionbudget of the sensor nodes. The extreme usage of power

Figure 1: Pervasive Health Monitoring System

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consumption in body area network leaded researcher tochoose an alternative solution and hence the emergingUWB technology is considered to be the best alternative.A pulse-based UWB scheme for body area network hasbeen proposed where the transmitter can be duty-cycledat the pulse rate which reduces the baseline powerconsumption [16]. ETH Zurich has presented a UWBchannel measurement with antennas placed on humanbody where the influence of the body on the channel ishighlighted [17]. Moreover, a UWB antenna for WBANoperating in close vicinity to a biological tissue isproposed in [18]. This antenna can be used in UWBwireless body area network applications between 3GHzand 6GHz. Within the framework of its Human++program, IMEC in collaboration with the UniversityHospital of Leuven, developed a prototype of a wireless

electroencephalogram (EEG) [17]. A Low-power star-topology BAN Controller is proposed at KAIST [19]. Intheir work a low power controller chip is designed inorder to reduce the baseline power consumption. Anintelligent for wireless body area network has proposedfor stress mentoring [20]. A arrhythmia systems ispresented for sending ECG signals with GPS data overGPRS network [21]. The 802.11 WLANs with Bluetoothtechnology can be used for transferring the patient’s vitalinformation such as ECG signals [22]. Ad-hoc wirelessnetworks can also be used in health monitoring aspatients can transmit their vital information to the nearby patients and so on until it received by the health careexperts [22].

4. RESEARCH ISSUES AND CHALLENGES

Health care monitoring with WBAN is a real-time serviceand requires strict and quality requirements [22]. Thehealth monitoring with WBANs may become reality butit includes a number of research challenges [4].

System Design Issues

The trouble-free use of health monitoring requiresextremely low power, light weight and small size sensors.The system should be environmental aware and ensurereliable and secure communication [23]. The systemrequires flawless configuration, integration and intuitiveuser interface.

Interoperability

Since WBAN is new and developing technology anddoesn’t have well defines standard, therefore,interoperability becomes an important issue such asdifferent sensors and prototypes developed by differentorganizations follow different standards. Differentsensors working on different frequencies, and differentcommunication protocol such as ZigBee, Bluetooth needsto work together in a reliable fashion.

Reliability

Since the health monitoring requires real time data inorder to provide better recommendations to users butthe application can not guarantee reliability due tounavailability of bandwidth, communication range etc.Therefore reliable communication is a challenging issuefor health care service providers.

Security and Privacy

Security is another important aspect of wireless BANsince the WBAN uses transmit patient’s data throughthe internet which requires reliable encryption algorithmto secure patients vital information, and creating a secureapplication is also a challenging task.

Figure 3: Accelerometer, Gyroscope, and SensorElectromyogram (EMG) Sensor

Figure 2: Wireless Pulse Oximeter

Source: http://www.eecs.harvard.edu/~mdw/proj/codeblue/

Source: http://www.eecs.harvard.edu/~mdw/proj/codeblue/

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Software Issues

Since the health monitoring system consists of largenumber of physiological sensors and operates in highlydynamic environment. University of Oregon hasdeveloped a mechanism called resource qualificationwhich allows the monitoring system to check theavailability of sufficient resources required to sendpatients vital information [24]. Wireless BAN requiresefficient prototype and software methods for reliable andsecure communication

5. FUTURE TRENDS AND CONCLUSIONS

Wireless BAN is a promising technology has a greatpotential in long term health monitoring and can providebetter quality life and health awareness. Though WBANis still in development stage, few companies aredeveloping product in order to make life better andhealthy such as Patient Home [25], iRevive [26], etc.Future applications include smart health care services,remote diagnostic and telemedicine, wearabletechnology to monitor vital signs, smart nursing homes,emergency communication and patient’s datamaintenance. WBAN requires the resolution of manytechnical issues and challenges such as interoperability,QoS, scalability, design of low power RF data paths,privacy and security, low power communicationprotocol, information infrastructure, and data integrityof the patient’s medical records. An adaptable wirelessBAN requires the use of broadband signaling schemesuch as UWB. The protocol such as WASP and CICADAneeds further improvement in order to provide uplinkcommunication from sink to the nodes. In future, we aimto modify the existing BSN platform by disabling the onboard radio (which uses ZigBee) and investigate the usesof UWB technology on body sensor network (BSN)platform. The received physiological signals from BSNnode will be calibrated into FCC mask. The calibrationprocess is a challenging task due to the discrepanciesbetween higher and lower frequencies. The integrationof UWB technology on BSN node could satisfy the energyscavenging limit and improves the lifetime of sensornodes.

We described the importance of wireless BAN inhealthcare applications. Furthermore, we discussedabout WBAN and BSN architectures. Current researchand development in wireless BAN has briefly discussed.Finally, we described the technical issues and challengesin wireless BAN along with alternative solutions. Webelieve that Wireless BAN will remove the restrictionfrom the patients and allows them to move freely whilemaintaining their health status.

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[21] K. Liszka, M. Mackin, M. Lichter, D. York, D. Pillai, D.Rosenbaum, Keeping a Beat on the Heart, IEEE PervasiveComputing Magazine, 42–49, (Oct–Dec 2004).

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