THe BANs (Body Area Networks) is a combination of micro and advanced Nano technology components for to improve the speed and accuracy of data recording. Generally BANs consist of small but sensitive sensors and actuators for monitoring and log data, then data sent to base station for storage. Users can access to this data in base station via internet or by other mean. BANs are actually a modern invention and primarily design for health industry (doctor and other staff) to monitor the health status. By taking the benefit of this technology we can monitor much more closely patients with chronic diseases like, asthma and diabetes. Doctor update the patients record quickly and efficiently to store general information of patients health.
In United States and other part of Europe, they made different pilot programs to monitoring patient's health status. They introduced bracelet with chips and antennas that can used to follow the patient position. They attached antennas on patient cloths to track him in the hospital and it send alert when he begins to collapse. A company is currently working on a project Healthy Aims [1] which focused on body devices that helps millions of people. Body Area Networks take low power radio frequencies (RF) and transfer the data of patients in real time. Doctors are able to monitor and change the setting for specific deployed devices on the body to improve the performance devices as well patient health. Pacemaker devices was produce 1960's have to endure pain and stress of surgery because it setup as a part of the body and send the patient health situation to RF transceiver, where it send directly to the doctor. This time interval always up to date the doctor about patient. By BANs Doctor and his staff can access to patient record at any time so they don't need to visit the patient or patient don't need to visit the clinic, it is a good method in prospective of save time and money by visiting the clinic many time during the month or weeks.
BANs is extremely compact and may be complex by its design, but as the sensor devices are very unassertive and a patient will be able to live a normal life. All sensors have same controlable mechanism like same element, power supply, and wireless transceivers. But they are design in such method that they can self-govern for the entire life [2]. They are designed for the measurement of temperature, movement, and location. Sensor and actuator implanted inside the body and they interact wirelessly each other's in BANs and process data is transmitted from implanted devices to external devices. Mechanism of a actuator is like environmental agent. In BANs the data passes through sensor to sensor then sent to it base station where it can be transmitted to recipient via internet.
2. Body Area Networks History
History about the body area network is not so old to go back many years to find out some material about BANs, taking advantages of some tiny useful technology in this sense is a new and unique idea. A number of different groups was work on PAN(personal area network) in Massachusett Institute of technology and that later grew out of the work on 1990's. The group actually wanted to get the information by interconnect different appliance on the body and to measure the position of the body by using electric field sensor. The main head for developing Personal Area Networks was Thomas G. Zimmerman. He introduces the new technology that allows the body to act like conductor. There was another name Neil Gershenfeld in that field who was in the Massachusett Institute of technology, incharged of the Media and Physics group. He and his group applied a method near -field coupling to solve the problem of determine the accurate position and its relationship with other parts, by fixing pairs of antennas on body part for example elbow and hand, and then run an electric current through them. They learned that as one move the capacitance of the circuit was charged. So they determine the exact position of the antennas after measuring the capacitance.
There was a problem in the measurement method that the measurement was no longer accurate if hand was placed between the antennas but it was solved by the Zimmerman. There was actually another group working in the Media lab asked them to develop a network such that all electric gadgets that a person can carry are connected together.
Many people carried digital devices around thereself but no one communicate to other.For example a person who has a mobile phone, a pager, a PDA or a digital watch mean all about his person at the same time. They both Zimmerman and Gershenfeld learned that, they can represent 1 or 0s, if they modulated the electric field which flowing through a person body,and allowing the body to carry digital information. At the end they discovered that if they used frequency and power that kept very low then the signal will not propagate far beyond the body. It mean that if devices could detect the signal on the body. This used of current at very low or small amount was unnoticed by anyone before.
3. Body Area Network Applications
There are many possible application for communication like in the hospital, in patients monitoring system at home (post-operative care), use in a large scale throughout the world. There is also a list of BANs usages in various field like in sport, military, mesh, and in sport fields.
Body Area Network Sports Applications
In the present sporting arena many different readings are possible to take without having an athlete on a treadmill in a laboratory. It provide the platform to measure various levels during different competition in real life, for example in race, where coaches, need his pi athlete's strengths and weaknesses.
Body Area Mesh Network Applications
The body area network consist of low-power and very reliable sensor networking. The low power usage allows longer life Batteries of motes or Gateways. The mesh network provides high reliability and long range communication. Mesh Networking is much more reliable and much capable of data sending
Body Area Network Medical Applications
Body Area Networks (BANs) can be used to provide interfaces for diagnostics purposes, in the hospital they used for administration of drugs, aid rehabilitation, and for remotely monitoring human physiological data. And for future prospective in hospital or at home it is used for monitoring the patient continuously and give required medication. So by this way patient need no more in the hospital with connected machines for monitoring.
Body Area Network Military Applications
Body Area Network has done a tremendous job in the military. So many of the military applications that we can use includes, their locations, health monitoring, their temperature and hydration levels, also very useful to enhance the strength, and many more factors for military prospective.
3.2 Body Area Network Devices
3.2.1 Body Area Network Sensors
With rapid improvements in medical research, more and more health sensors have been developed to assist caregivers in monitoring their patients' conditions. These sensors have been getting smaller, making it possible for the sensors to be worn or to be implanted into the human body.
3.2.2 Body Area Network Actuators
The most significant products by any company would be the actuators that actually transforms or converts energy into motion., An actuator is usually a mechanical apparatus and also applied as a force that takes energy, usually constructed by a special kind of liquid, air, or electricity, and converts them into a specific type of motion. These kind of product would help to build a model of effective engineering designs in a safe, easy, and efficient manner.these product can be implemented anywhere according to the requirement. [3]
3.2.3. Body Area Network Devices usages
Two main non-computer devices (sensors and actuators) can be used in BANs network. The main function of sensors are to measure human body parameters like temperature, electrocardiogram, heart beats rates and the pressure on the joints, These can be taken insidly or outsidely of the human body. Whereas Actuators have some particular action like to get the information received by the sensors and do work on instruction given by web or PDA. They are as following
For monitoring muscle activity we can use an EMG (electromyography) sensor .
For monitoring brain electrical activity we can use An EEG (electroencephalography) sensor.
For monitoring trunk position we can use tilt sensor (TS).
For monitoring respiration we can use breathing sensors.
For monitoring heart activity we can use ECG (electrocardiogram) sensor.
A sensor for blood pressure.
To estimate a users' activity we used movement sensors (MS).
Fig 2: A BAN on an Athlete :
http://www.sintef.no/home/Information-and-Communication-Technology-ICT/Instrumentation/Biomedical-Instrumentation/Body-Area-Networks/
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3.3 Body Area Networking
Before implementing the Body Area Network, a number of networking issues need to be solved. In this interferences when a node sends data (after processing) directly to central devices there is direct communication that might causes unnecessary rises of temperature in the tissues, there is another way data is sent through intermediate nodes to the destination by multihop communication. The data might pass to other nodes to the way to PDA if node attached to foot, that mean that at the same time the number of data pathways night exist in the same tissues. Node are like routers but it eliminate internal interference and more energy efficient. In PANs communication IEEE 802.15 standard used which basically sure that all group devices in the design of BANs should work with all togather.
3.4 Body Area Network Software
UC Berkley in California is developed "Tiny OS (Operating System)" which is an open sourse operating system in used wireless embedded sensor network.OS is extremely small in sense of memory and code writing which make it suitable for sensor network where they use minimum memory. The search is going on by using this tiny OS in sensor networks to measure some extra ordinary work . For examples sensor networks that are used to monitor volcanic eruptions and tracking/tracing (for help purposes) of fire fighters in buildings. There is a another option available that is toolkit of MSR network embedded sensors that allow user to perform different actions like process the data, collect data, and also visualise data from sensor network. The search is still going on so let us see which development OS or MSR come fist but till yet both available for free download.
4. Challenges of Body Area Networks (BANs)
Body Area Networks (BANs) consists of tiny sensor that actually placed around the body (attached on the skin or on the cloths), which take power from attached battery or from body. In BANs all the nodes communicate collectively to the central node (PDA) or other devices which are connected to the internet so data pass through to a particular person or to a particular application.
There are a numbers of challenges still in BANs networks which must be overcome by engineer, they are as following:
Power sources of life timer needs to be increased in the sensors networks (SN), or adopt different methods to get energy from other sources like body heat so it also should be perfected.
The interaction of the different sensors or nodes and the main node like PDA, that should be designed in such a way that it allow some specialist applications to be written to perform particular functions for example disease management.
The device needs to be intelligence in sense of memory and processing capabilities for processing, storing and transferring the data.
To give a full and clear picture of human physiology, Sensor need to be integrated Physically, Chemically, and Biologically and the BAN components integrated for reliable and cost effective way.
5. BANs User Cases for System design:
Body Area Networks (BANs) technology actually develop biomedical engineering according to the natural byproduct of existing sensors. Actually this technology is suitable for any scenario by its low bound of power and bandwidthHowever,there are many potential to use BAN technology due to its flexibility that is as following,
Body Sensor Networks (BSNs)
Integration of different mobile devices
Different personal video devices (VD)
Audio system of wireless (WS).
Monitoring system for sport and fitness.
Each case have unique requirement in term of bandwidth, power usage, signal distance and for latency. These cases use IEEE 802.15 standard which is use for different working group in wireless personal area networks (WPANs). So they think to use this standard within different devices for inside and around the body.And later they develop the standard for BANs and introduces a long range of possible devices to support this standard. For power balance and data rate the task group gave applications and appropriate devices for development. The figure below describe the comparison between power load and data rate in BANs.
Fig (1) comparison between data rate and power.[1]
In the above picture as we can see the range of different devices which can be used in BANs in comparison of power consumption and data rate. The table below also give us a full picture of devices that conform to work in a similar set of requirement, according to the demand of user case, yet still encompass a wide range and variety of device
5.1 Zigbee wireless sensor technology
We can describe ZigBee in some specific manners of a low-cost, low-power wireless communications that has a useful design to fulfil our needs our architecture requirements.Now these days ZigBee is of high level Communication protocols that use in small, low power digital radios bases design that work on wireless personal area Networks standard IEEE 802.15.4. There are different kind of layer active in Zigbee protocol. The standard of Zigbee protocol contains the specifications of the network and application layer. Inside the application layer of Zigbee protocol, functions are defined separately as, The application support sub-layer (APS), The Zigbee device objects (ZDO) The Zigbee device profile (ZDP) The application framework (AF) The Zigbee security services. [4]
5.2 Zigbee with OSI Layes
Basically Zigbee builds upon on two main layers, physical layer and medium access controls that are defined in IEEE standard 802.15.4 for low-rate Wireless Personal Area Networks. There are four main components added to complete the standard 1.network layer, 2.application layer, 3.Zigbee device objects (ZDO's) and 4.manufacturer-defined application objects that use for customization and favor total integration.
The most significant improvement in zigbee stack is the introduction of Zigbee device objects (ZDO's),which is responsible for a number of tasks, which include keeping of device roles, managing the request to join the architecture network, device discovery and security.[5]
Fig4.1.Zigbee,stack. http://en.wikipedia.org/wiki/File:ZigBee_protocol_stack.png[6]
5.2.1 Network layer
The main purpose of using the network layer is to correctly use the MAC sublayer and suitable interface which use by the next upper layer, that is actually an application layer. It has also routing capabilities and because its structure is typically associated to such network layers. According to the current architecture that perform routing which we are using, the data entity creates and manages by network layer data units from the payload prospective of the application layer, in case we want to establish a new one there is the layer control, that can be used to handle configuration of this new devices for the establishment of new networks, actually It determine whether a new neighboring device belongs to the network or not, and also discovers new neighbors around, and routers. The control can sometimes detect the presence of a receiver, then it allows direct communication called MAC synchronization.
The routing protocol that are used by the Network layer is the Ad hoc On-Demand Distance Vector Routing (AODV), that broadcasts out for a route request to all of its neighbors in the architecture, in order to find the destination device. Then latterly the neighbors broadcast the request to its neighbors (that lies around it) until the destination is reachable, and following by lowest cost path back to the source it sends its route reply via unicast transmission when the destination is reachable. So the source receives the reply, then it updates its routing table (with the next hop in the path and the path cost) for the destination address.
5.2.2 Application layer
According to the specification the application layer is the highest-level layer, and in Zigbee system it is the effective interface to its end users and endpoints. And by the Zigbee specification and Zigbee devices objects It comprises so many components added for management procedures, and together with application objects it is considered part of this layer that are defined by the manufacturer.[8]
5.3 System Capability Requirements
The characteristics of sensor networks and requirements of different applications have a vital role on the network design objectives in terms of network capabilities and network performance. The main design objectives for sensor networks include the following several aspects.
Small Node Size:- Reducing node size is one of the primary design objectives of sensor networks. Reducing node size can facilitate node deployment, and also reduce the cost and power consumption of sensor nodes.
Low Node Cost:- Reducing node cost is another primary design objective of sensor networks. It is important to reduce the cost of sensor nodes so that the cost of the whole network is reduced.
Low Power Consumption:-Power is a major role in any System prospective. Reducing power consumption is the most important objective in the design of a sensor network. Since sensor nodes are powered by battery and it is often very difficult to change their batteries, it is crucial to reduce the power consumption of sensor nodes so that the lifetime of the sensor nodes, as well as the whole network is prolonged.
Self - Healing:-In sensor networks, sensor nodes are usually deployed in a region of interest without careful planning and engineering. Once deployed, sensor nodes should be able to autonomously organize themselves into a communication network and reconfigure their connectivity in the event of topology changes and node failures.
Scalability:-In sensor networks, the number of sensor nodes may be on the order of tens, hundreds, or thousands. Thus, network protocols designed for sensor networks should be scalable to different network sizes.
Adaptability:-In sensor networks, a node may fail, join, or move. This result changes in node density and network topology. Thus, network protocols designed for sensor networks should be adaptive to such density and topology changes.
Reliability:-For many sensor network applications, it is required that data be reliably delivered over wireless channels. To meet this requirement, network protocols designed for sensor networks must provide error control and correction mechanisms to ensure reliable data delivery.
Fault Tolerance:-Sensor nodes should be fault tolerant and have the abilities of self - testing, self - calibrating, self -repairing, and self - recovering.
Security:- Sensor nodes are deployed in a open environment and thus are vulnerable to adversaries. In such situations, a sensor network should introduce effective security mechanisms to prevent the data information in the network or a sensor node from unauthorized access or malicious attacks.
5.4 System Environment Requirements
For system environment, the system must be reliable, safe and it must work under certain environment in regards to temperature and humidity. System devices should cover certain area and performance. It is essential to choose correct devices and locations which will facilitate the purpose for using all selected devices in the system. System devices must be able to communicate with all other devices in the system.
6. Research Pappers.
A number of major operations on Mobilehealth are being conducting all over the world especially in European countries like Sweden, Germany, Spain, and Netherland. It is used to monitor a limited range of condition in patient outside the hospital by the medical personnel.
Germany:
Telemonitoring of patients with cardiac arrhythmia.
The Netherlands:
Integrated homecare for women with high-risk pregnancies, Tele trauma team.
Spain:
Support of home based healthcare services, Outdoor patient rehabilitation.
Sweden:
Lighthouse alarm and locator trial, Physical activity and impediments to activity for women with RA, Monitoring the vital parameters in patients with respiratory insuffiency, Homecare and remote consultation for recently released patients in a rural area [7].
But a number of different issues arose as a result of these trials like handover, operator errors, data rate fluctuation, and the most common issue of power supplies insufficient. There are also some other issues like privacy and security (For instance, will the data that is being transferred remain private or is it secure), control and legal issues (may someone send false information to the network ) regarding BANs. If someone tell it to perform some dangerous function like make a patient warm or overdose, or is this legal to inform someone like companies that are interesting about its work weather he/she has weak heart or having any kind of disease in advanced BANs. Lastly some imported functions are operated and controlled by the computer that can be damage or stop working at any stage and the actuators that regulated the flow of certain chemical in the body stop then who is responsible, so these issues need to be address before BANs applied in the daily life routine.
