A Survey of Body Area Networks

This paper is written for my Wireless Network Security presentation

A Survey of Body Area Networks 

Celal Ergun 

Istanbul Commerce University 

celalergun@gmail.com 

Abstract 

Body Area Networks (BAN) refers to a data acquisition system which uses wireless communications to deliver the collected data. There are medical and non-medical uses of these systems. The general idea is to use the low power low speed communications to log the sensor outputs. There are a number of sensors for most of the measurements such as temperature, pressure, movement, acceleration and like. This area of the technology has its own challenges, e.g., low variety of sensors, battery lifetime, communication speed and communication range. 

1. Introduction 

The term BAN (Body Area Networks) is used for measuring body condition via sensors and sending the data over a network connection. This technology is not anywhere near what we are expecting of. But the good news is that its emerging and we have lots of new computing chips and sensors in comparison with the last decade. There are a number of papers published on this subject on different areas of the domain. Some of those papers are on battery technology, including self-charging systems. Most of the rest is concentrating on networking and thus, network security.  

2. BAN in a nutshell 

BAN systems are consisting of sensors, computing units and communication interfaces. When it comes to sensors one would find out that there are three kinds of sensors.  

a. Implant sensors 

b. Skin mounted sensors 

c. External sensors 

Implant sensors are hard to install and hard to maintain kind of sensors, usually required medical operations to embed into the subject's body. They usually used to monitor heart, lungs, pancreas and kidneys. There is an additional problem to these sensors: power. It is not possible to use nuclear long-life batteries in human body. These sensors mostly run with a battery and this battery needs to be changed from time to time. To overcome this situation, one could use a wireless power transmission to recharge the batteries [1]. Most of the heart implants use a long-life non-rechargeable battery and they need to be replaced every six years. However, Dagdeviren et al. [2] invented a self-charging device which uses piezoelectric materials and harvesting the mechanical body energy in form of electricity.  

Skin mounted sensors are easy to use and easy to recharge devices because they are not needed a medical operation to install. Although they are limited in terms of information collection about the body, they have their place. Skin mounted sensors are useful to measure blood pressure, heart rate, stress levels, blood sugar etc. They have no battery problem due to their nature since they are surface mounted mostly with a Velcro strap. Usually, they are mounted to the wrist and chest of the subjects. 

External sensors are the least informative sensors. They are used by athletes such as hikers, mountaineers, swimmers etc. Usually they measure atmospheric pressure, altitude, environment temperature, speed and acceleration. They are the least prone systems in terms of battery power. They would use high-capacity power-banks and even power outlets to run. 

A BAN device not always need a sensor to work, however. There are other devices that might be considered a BAN device and has no sensors or whatsoever. Some of the examples of that devices are, including but not limited to medicine reminders, step counters, calorie counters, wireless payment devices etc. 

Now let’s look at the network part which makes a BAN unit a network device. 

3. Networking and topology 

There are four topological schemes on body area networks. 

a. In-body link 

b. On-body communications 

c. Body-to-body link 

d. Off-body link 

BAN devices use different communication protocols. Most popular communication protocols are: WiFi, Zigbee, Bluetooth and IEEE 802.15.6. 

Bluetooth communication is the most popular way when it comes to the wearable devices. Since it is proven and reliable in short ranges, they can easily be used in smartphone powered applications.  

Smartphones are usually the hub of these systems. One or more sensors gather data, make computations on it, store in a volatile or nonvolatile means of memory and then the device will send it over the Bluetooth to the smartphone. 

There are also web sites to display and share this information. One of the most popular examples is the MapMyRun (formerly known as Endomondo) service [3]. The service tracks the training path, measures maximum and average speed and of course, sharing it with the friends.  

Bluetooth communications are common, easy to implement, inexpensive due to the cheap communication chips, low power and are field-proven. There are also audio and visual aids which can be considered BAN systems that uses Bluetooth communications. 

However, when it comes to BAN communications, we have another choice: IEEE 802.15.6. This communication protocol has 3 different speeds: 250 Kbps, 40 Kbps and 20 Kbps. There are two different addressing protocols which uses 16 and 64 bits addressing. It has PHY and MAC (Media Access Control) specifications. The communication range is limited due to the 

a. Security considerations 

b. Low power requirements 

802.15.6 is specifically designed for BAN communications. Body implants and skin (surface) mounted sensors may use it. Their operating frequencies are selected among the safest frequencies for human body. 

4. Security 

Security of BAN networks are divided into four main parts of OSI (Open Systems Interconnection) layers 

a. Physical: Jamming and tempering 

b. Link: Collision, unfairness, exhaustion 

c. Network: Blackhole, Sybil, selective forwarding 

d. Transport: Flooding, de-synchronization 

Jamming and tempering are denial attacks which makes it hard, if not impossible, to communicate with the hub or server systems.  

Collision attacks are also another denial attack type which makes the communication unreliable. Exhaustion attacks are dangerous by the nature but when it comes to critical health support systems, they are lethal. 

Sybil attack is named after a book, which describes the life of a borderline woman. This attack creates many different profiles using a replay attack. 

Flooding and de-synchronization attacks are used to disrupt communications by making transport layer unstable.  

BAN systems are mostly consisting of wireless communications and are mostly prone to PHY attacks. 

These low-power systems cannot implement hard-to-break cryptography schemes due to their low power nature and can be broken within a relatively short time [4]. 

5. References 

[1] Battery-Dynamics Driven TDMA MAC Protocols for Wireless Body-Area Monitoring Networks in Healthcare Applications  

Hang Su,Student Member, IEEE, and Xi Zhang,Senior Member, IEEE 

[2] Recent progress in flexible and stretchable piezoelectric devices for mechanical energy harvesting, sensing and actuation 

Canan Dagdeviren, Pauline Joe, Ozlem L. Tuzman, Kwi-Il 

Park Keon Jae Lee, Yan Shi Yonggang Huang, John A.Rogers 

[3] https://www.mapmyrun.com/ 

[4] Challenges in Wireless Body Area Network  

Muhammad Asam, Tauseef Jamal, Aleena Ajaz PIEAS University, Islamabad, Pakistan 

Muhammad Adeel, Areeb Hassan, 

Superior University, Lahore, Pakistan 

[5] A Survey of Challenges and Applications of Wireless Body Area Network (WBAN) and Role of a Virtual Doctor Server in Existing Architecture 

Deena M. Barakah, Muhammad Ammad-Uddin 

[6] Survey of main challenges (security and privacy) in wireless body area networks for healthcare applications 

Samaher Al-Janabi, Ibrahim Al-Shourbaji, 

Mohammad Shojafar, Shahaboddin Shamshirband