Effect of Channel Modeling on Intercept Behavior of a Wireless BAN With Optimal Sensor Scheduling

Body Area Networks

The usage of wireless links is a fascinating replacement for wired cables coupling various wearable devices. Body area networks (BAN) are a type of personal area networks (PAN). BANs form a significant part of health care applications due to increase in medical expenses. Moreover, the patients suffering from chronic diseases who require only restorative observation need not be admitted to a hospital as this can be easily done via intelligent monitoring of the patient’s body using wearable devices. According to Moore’s law, the development of small and handheld devices which could be used for communication around human bodies was certain. An example of BANs is pacemaker. Other applications are smart pills for monitoring glucose, deciding on drug delivery and systems for sensing eye pressure. In the same way, wearable computing is an interesting application such as physiological/medical monitoring of temperature, heart rate, and blood pressure, etc. A BAN comprises of a number of sensors that are implanted inside the body, or are simply allocated on and around it along with a hub. The hub or the sink node can be placed on the body itself or alternately near it. The placement of on-body hub is generally done near the torso. BANs are meant for long-term use. To elongate the life of a BAN, low power sensors with a short range are employed. Other methods taken into account for long term usage of a BAN are communication using relays, controlling transmitting power of a sensor and adapting the link between sensors accordingly.

Operational Scenarios for BANs

The various operational scenarios for BANs can be:

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  On-Body: As the name suggests, in case of on-body BAN, communication will take place from one place on body surface to some other place on the body surface. It is the most widely used operational scenario.

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  In-Body: The transmissions are generally done from a sensor implanted inside the body to one which is placed on the body. This is because doctors prefer to implant as few sensors inside a body as possible for the obvious reasons. So even when an implanted sensor needs to communicate with a similar sensor, the preferred path is often via some on-body sensors which act as relays. The in-body BAN mostly works in coordination with on-body BAN.

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  Off-Body: It comprises of wireless communication from a sensor placed on the body to a closely placed device (or vice versa) whose distance of employment should not exceed 3m.

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  Body-to-Body: They support communication from one subject’s body to another subject’s body.

Frequency Bands in BANs

IEEE Standard 802.15.6 is used for short-extent, wireless transmissions in the proximity of a human body (though not restricted to humans). This standard makes use of ISM band and certain other bands in combination with frequency bands in agreement with relevant communication and medical regulatory authorities. It lets devices to work on quite low transmit power in order to reduce the Specific Absorption Rate (SAR) into the patient’s body to minimal levels while increasing the battery life (Fields,1997). It enhances Quality of Service (QoS), for instance, by providing emergency messaging (Smith et al., 2013).