Wireless Body Area Network Technology

INTRODUCTION

A Body Area Network is defined by IEEE 802.15 as a standard for communication in or near the human body that can serve a variety of applications like medical testing, electronics and private entertainment optimized for low power devices and operation” [1]. In more common terms, to cooperate for the benefit of the user Body Area Network is a device system in a close contact to a person’s body.

A Wireless Body Area Network is capable of establishing a wireless communication link consists of intelligent and small devices implanted or attached in the body. These devices provide health monitoring for continuous and provides feedback to the medical personnel or user which is real time. The measurements can be recorded and used over a long period of time.

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There are two types of devices can be used for evaluation: sensors and actuators. The sensors, internal or external, are implanted on body to measure some parameters of the human body. For example body temperature, measuring the heartbeat or recording an ECG readings. The actuators can take some specific actions according to the data received from the sensors e.g., any sensor equipped with a built-in reservoir checks the correct dose of insulin to give, based on the glucose level measurements, to a diabetics patient.

In body area network for medical purposes, a number of sensors are implanted on patient’s body. These sensors collect the data from body and send collected data to the main sensor. This main sensor analyzes the data and takes specific action. It sometimes consists of actuator which is used for taking required action. For eg. the sensors collect the data from body of a diabetic patient and sends it the main sensor. The main sensor analyzes the data and if it is dropped then it can inject insulin into the body of the patient and make it comfortable till the main medical aid it gets.

IEEE 802.15.4 is a standard for low-rate (LR) WPANs. A LR-WPAN network allows wireless connectivity in applications with limited power, low cost and simple communication and relaxed throughput requirements.[4] Ease of installation, extremely low cost, reliable data transfer, short-range operation and a reasonable battery life are the main objective.

There are different type of topologies are used in communication system for different purposes and according to our need. Topologies which are used widely are : Star ,Mesh and Cluster, Ring, Bus topology. On the basis of average jitter, throughput, end –to-end delay, traffic bits sent, traffic bits received, we can find out that which topology is good for our system. With different topologies come different routing protocols. The routing protocols to be used with zigbee protocol are AODV, DYMO, DSR etc. In wireless communication, there is no any fixed or dedicated route is assigned between two nodes for communication. Whenever , they want to communicate with each other or any other node they request for route to the system and these routing protocols , according to their properties find out the best route for communication. That route will be shorter in length so that their won’t be any delay.

Body area network is being used very widely in today’s high tech world. Mainly for body area sensors detection, health monitoring and for providing assistance to differently able persons. Below are some of the advantages of Body Area Network:-

1. Quick transmission time
2. Reliability
3. Good quality of service
4. Different data rates can be used
5. Compatibility
6. Low power required (as work on battery)
7. Security (because of encryption)
8. Portable

As there are many kind of routing protocols and topologies are available for communication. There are routing protocols like AODV, DYMO, Bellman ford ,LANMAR etc but it depends on type of requirement and demand that which protocol is suitable for our purpose. So, in this project we will try to find out that which routing protocol is better for our system with suitable toplogy like star, mesh etc. In this project we have zigbee based wireless sensors for monitoring. It defines the upper layers like physical and MAC layer. It is suitable choice for monitoring medical purpose sensors. Every node will sense the data from body and collected data will be sent to main node. We will design and simulate these systems on Qualnet then we will make comparison between them on the basis of throughput, average jitter, average end-to-end delay etc. The performance of each topology will be compared with every routing protocol.

TECHNOLOGY TO BE USED

BODY AREA NETWORK

Introduction

With the invent of new and high tech environment there is need of small, low power, light weight, portable devices with sensors. These devices can be used at low data rates for improving speed and accuracy. A number of these devices can be implemented on body for the monitoring of body sensor networks for applications such as health monitoring. In a body area network , it consists of small, portable devices that can be easily implanted on one’s body and they can establish wireless network link. These devices take the data continuously for health monitoring and provide real time readings to the medical examiners. These readings can be recorded and can be used for long time.

A body area network generally consists of actuators and sensors, which can be implanted on or inside the body. These sensors are used to collect data. Like for eg. taking heartbeats, taking readings of ECG or temperature of body etc. The actuators take required actions on the basis of data they receive from sensors or from users. Sometimes these actuators have in-built pumps or reservoirs that keep on checking the dose of insulin and it can inject it inside body if needed. It is helpful for diabetic patients. The communication with other person or user can be done by portable wireless devices such as smart phone or PDA.

The body area network works on the principle in which data is received through implanted devices and transmitted to external devices. The sensors implanted in or outside the body interact with one another and to the actuators. The actuator is based on the process of taking action according to the surrounding conditions. All the sensors send their data to main sensor. The main sensor collects the data from each sensor, fuses it and sends it to the particular person via internet. Generally, body area network comprise of small sensors and devices therefore ad-hoc network is best suitable choice for this kind of network. The IMEC (Interuniversity Micro Electronics Center) working on the principle to get hospital to the nearest location with patient. It is gives the patient the freedom of not going to hospital on regular basis for checking and taking his readings. The patient is now out of worries of regular check-up. The devices itself will take the readings and pass it to the concerned doctor and according to the readings it can take required action too, without the need of any medical personnel, in case of emergency.

Architecture

A body area network has a network created in or around the human body. The architecture of the body area network is as shown below.

Figure 2.1 Architecture of body area network

Figure 2.2 Core of body area network

The proposed architecture of body area network as shown in figure 2.1 consists of following elements :

1. Sensors: These are used to collect data from the different parts of the body continuously and transmitted this data to main sensor.
2. Main sensor: The main sensors collect the data from other sensors and fuse it together. Then it supplies this data to coordinator.
3. Coordinator: The coordinator analyzes the data and takes suitable action, if required otherwise send this data to PDA being used by the user.
4. PDA or smart phone : These are the devices which get data in the form required from the sensors and transmit over the network to the laptop or desktop, wherever it is being recorded for future purpose.

The core of body area network as shown in figure 2.2 consists of several body sensor units (BSU) and one body control unit (BCU).

Applications

1. Medical Applications

With the invent of new technology and fast processing, there was need of speed, comfortablity and convenience in the field of health monitoring too. So, with the help of body area network, it became possible and easy to monitor the health of patient remotely.

2. Sports Applications

In the field of medical, it can check the health of athletes and can give a accurate and clear picture about it to their coaches so that they can determine their weaknesses and strengths. It can be used in measuring many factors during competitions like race. This kind of observation can be done anywhere and there is no need of going to laboratory and running on trademills everytime for taking readings.

3. Entertainment Applications

Body area network can be used for entertainment also. It can be used for gaming, multimedia applications, 3D video and video buffering etc.

Issues involved

1. Sensors: What type of sensors should be used? The types of sensors to be used depend on the requirement and purpose.

2. Source of power: These devices are to be used for a long time and continuously therefore power source should be continuous and strong.

3. Communication Range: The range of the system should be such that it can give person nearest location help and should not get disconnected even if it is far.

4. Size and weight: The size of the sensor should be small enough to be get implanted on body easily and weight should be as minimum as possible. Because a number of sensors are to be implanted on body so it should not be difficult for the person to carry them over his body.

5. Mounting of sensor: The sensors should be implanted at the correct point of the body so that sensors can take the readings correctly. If they are mounted incorrectly then system may not get the required reading. If the sensors have to count heartbeats then sensors should be placed near heart for taking data.

6. Robustness: There is very less probability of taking wrong readings if the readings are taken incorrectly then it can cause big problems.

7. Synchronization: The sensors should be synchronized with each other and with main sensor. They should be working in real time.

8. Cost: The cost of the system should be low so that more number of persons can use it and could be used for mass production.

ZIGBEE PROTOCOL

Introduction

SIMULATION AND RESULTS

Simulation is the main process of finding out the performance of the proposed system. It tells us the ability and efficiency of the particular system when it is used under different system, surrounding and environmental conditions. It tells us that how really our system is going to work in a real environment and what factors should be taken care of while using and designing it .So, instead of designing any factory prototype of system before , it is simulated and ran on software by virtually designing it.

In this project we are working for IEEE 802.15.4 zigbee protocol for body sensor network. We have used two topologies : star and mesh. We have used software QUALNET 5.0 for simulation of our scenarios that is star and mesh for different routing protocols such as AODV and DYMO.

QUALNET 5.0 is a product of scalable technologies and is a good software for designing and simulating wired and wireless networks such as wi-fi, wi-max, GSM etc. There are a number of protocols available for simulation of different type of systems. It also has 802.15.4 protocol for zigbee which can be used for designing body area network prototypes. Qualnet is chosen because of its accuracy and its available graphical user interface. Using qualnet we designed star and mesh topologies containing PAN co-ordinator, routers and a number of sensor elements and then we developed them for different routing protocols such as AODV and DYMO.

After developing them, we tested and compared them for throughput, end-to-end delay, average jitter etc. So that we can find out better performing routing protocol for respective topology used. The simulation results are shown as per respective factor for different topology showing performance on different routing protocol.

THROUGHPUT:

Any routing protocol in any network can send only a fixed amount of data over the route so if we are having a large bit message then we have to divide that data into a number of packets that can be transferred over the route to the destination. These packets have size which is applicable for the route. When these are sent over the network then some of the packets can get corrupted due to the noise or lost or discarded and not all of the sent packets will be received by the receiver. Then, throughput comes into picture which is the rate of the successful transfer of packets. It is measured in bps that is bits per second.

Below are the simulation results for throughput of star and mesh topologies :

The above result is shown for the throughput comparison of star topology for AODV and DYMO routing protocol at different nodes . It can be seen from the figure that the throughput is same for both.

The above result shows the comparison of mesh topology for AODV and DYMO routing protocol. From the above result we can see that throughput for DYMO is very less than the AODV. So it can be concluded that AODV is better than DYMO for mesh topology.

AVERAGE JITTER:

When a number of packets are transmitted over a network then there can be some delay (latency) over the network due to which the receiver will receive packet after the expected time. The variability in time can be observed for various networks. This variability in latency is jitter. A network which has no latency or constant latency has no jitter.

The above result is shown for comparison of average jitter of star topology for AODV and DYMO routing protocol. It can be seen from the above result that average jitter for AODV is larger than DYMO so it can be concluded that DYMO is better than AODV for star because it has less dealys for packet transmission. Also, it can be concluded that there will be less collision in DYMO because it is taking less time for transmission.

The above result is shown for comparison of mesh topology for AODV and DYMO routing protocol for average jitter. It can been seen from the result that DYMO has less jitter than AODV. That means DYMO is better than AODV because it has less latency. Also, it can be concluded that there will be less collision in DYMO because it is taking less time for transmission. Same was the result for star topology so it can be concluded that DYMO is better when it comes to the performance based on the jitter.