23-05-2014, 11:10 AM
WIRELESS BODY AREA NETWORK FOR MEDICAL HEALTHCARE
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Abstract
A body area network is a wireless network of biomedical sensors that are attached to a human body. The aim of wireless body area network (WBAN) is to facilitate continuously recording and monitoring of a person’s health condition, if needed, over a long-distance communication network. A sensing system is to be worn by the individual for a long duration. The hardware must be compact and light. This limits the size of the battery where the device depends on its duty cycle.
These factors have made energy the most critical resource in WBAN and extending system lifetime has become a priority to fully realize the capabilities of WBAN. This paper presents design and system integration of WBAN technology along with issues and technical challenges of WBAN.This device has the potential in creating a awareness about health and found to have uses in sports, diet and fitness monitoring, wireless audio, mobile device integration and personal videos. A sensor fixed along with the body having less weight can prevent from serious health complications and easy monitoring is made possible.
Introduction
Recent technological advances in low-power integrated circuits, wireless short-range communication, and physi- ological sensing allow miniature, lightweight, ultra- low-power intelligent monitoring devices [1]. A number of these devices can be integrated into wireless body area network (WBAN) – a new enabling technology for health monitoring. WBAN is expected to become a basic infrastructure element for electronic health services. By integrating patient-attached sensors and mobile actor units, distributed information, and data processing sys- tems, the range of medical worklow can be extended to include applications like wireless multi-parameter patient monitoring and therapy support. WBAN prom- ises inexpensive and unsupervised medical monitoring during normal daily activities for prolonged periods. The basic concept of WBAN is that a set of mobile phones/ personal digital assistant (PDA) would enable transfer of vital parameters between the patient’s location and their doctors through wireless or Internet. However, WBAN consolidates the data stream of all sensors nodes attached to the body and transmits the data to PDAs [2].
Wireless Sensor Network:
A WSN consists of a base station (gateway) that can communicate with a number of wireless sensor nodes via a radio link. Data are collected at the WSN nodes, processed, and directly transmitted to the gateway (single hop) or, if required, uses other nearby WSN nodes (multi-hop) on the way to forward data to the gateway, as shown in Figure 1. The transmitted data are then presented to the system by the gateway con- nection. Individual sensors have become smarter with the addition of micro-controllers. Smart sensors are now becoming wireless by including transceiver in the sensor node. A micro-controller manages data collection from the sensors, performs power management functions, interfaces sensor data to the physical radio link, and manages the radio network protocol. Generally, the radio subsystem requires the largest amount of power. Therefore, it is advantageous to send data over the radio only when required. The sensor event driven data collec- tion model requires an algorithm to be loaded into node to determine when to send data, based on the sensed event. It is important to minimize the power consumed by the sensor itself. Therefore, the hardware should be designed to allow micro-controller to judiciously control power to the radio, sensor, and sensor signal coordinator. Due to small size and low power, multiple sensors can be deployed to perform an entire function such as monitoring atmospheric conditions at the posi- tion of a node. The size of a single sensor node can vary from shoebox-sized nodes down to devices the size of a grain of dust.
Wireless Body Area Network
The WBAN technology has emerged as a natural byproduct of the existing WSN technology and bio- medical engineering. A WBAN intended for medical applications could be seen as WSN since most medical applications rely on the sensor collecting data, eg, for the heart and brain. A WBAN speciically tackles the chal- lenges associated with human body monitoring as well as the interaction of human and human body with the environment. The challenges are due to human body’s complicated internal environment and characteristics of the human body that responds to and interacts with the external surroundings. Sensors in WSN are numerous, homogeneous, and generally insensitive to placement errors. The WBANs, in contrast, are few, heterogeneous, and require speciic placement. Commercial wireless sensor nodes exhibit a wide range of power supply requirements, calibration parameters, output interfaces, and data rates. WBAN nodes requirements could neces- sitate an application-speciic approach to minimize the design space, improves eficiency, and reduces cost over a single application. The WBAN can include the number of physiological sensors or biosensors depending on end-user application. An extensive set of biosensors may include the following: an electrocardiogram (ECG) sen- sor for monitoring heart activity, an electromyography (EMG) sensor for monitoring muscle activity, an elec- troencephalography (EEG) sensor for monitoring brain electrical activity, a blood pressure sensor, a tilt sensor for monitoring trunk position, a breathing sensor for monitoring respiration, a motion sensor used to estimate user’s activity, and a smart sock sensor equipped in shoe insole used to delineate phases of individual steps. Sens- ing is fundamental to all WBANs and its quality depends heavily on industry advances in signal processing, micro- electromechanical system (MEMS), and nanotechnology (NEMS). Sensor falls in three categories: (a) biosensors: measure blood pressure (BP), continuous blood sugar, core body temperature, blood oxygen, respiratory rate, ECG, EEG, and EMG; (b) bio-kinetic sensors: measure acceleration and angular rate of rotation derived from human movement; © ambient sensors (WSN): measure environmental phenomena such as humidity, light, sound pressure level, and temperature.
Conclusions
The WBAN technology is quite lexible and there are various potential uses such as sports, itness monitoring, wireless audio, mobile device integration, and personal video devices. Battery lifetime is dependent on duty cycle
of the sensing node. Communication protocol within the node should be kept simple, and must not require a lot of computation and advanced signal processing. Wearable technology will silently monitor heart rhythm, detect irregularities, and alert emergency personnel in the event of a heart attack. Doctors can monitor a large number of patients simultaneously, which is not possible in tradi- tional monitoring (where, patients are monitored directly by the doctor). The patients are no longer required to be present in hospitals periodically. Fitness and entertain- ment are taking new dimensions in WBAN.