Joel Nuno Silva Alves BIOSWIM - Implementação de rede de ...

Abstract
This dissertation describes the development of a wireless sensor network used by a
biomedical signal monitoring system to be integrated in a swimsuit. The system will measure
various biochemical, physiological and chemical performance parameters, to allow a global
analysis of the behavior of the subject, as well as to signal abnormal behavior.
Data communication consists of a body area network (BAN) materialized as a wireless
network in two versions, one based on the 802.15.4 specification and another on the higher-level
Zigbee protocol, developed using the Jennic JN5148 microcontroller, Jennics ZBPro stack and
JenOs RT kernell. The system acquires, processes and sends signals from the sensors that will
be connected. It is also composed of a graphical application on a computer that graphically
represents the signals, controls the sensor nodes in terms of sampling rate and makes the
recording and presentation of the errors that arise in communication.
For demonstration purposes, a specific sensor for tympanic temperature measurement,
of the thermistor type, was used, to measure this variable during sports activity. A specific
conditioning circuit was developed and connected to a device node in the wireless sensor
network.
The final system was tested with the devices in different positions, as well as several
sensor nodes communicating simultaneously. For each of the relative positions of the devices the
signal quality and frequency of communication errors were recorded.
The version implemented on basis of the Zigbee protocol was able to acquire and send
sensor signals at a frequency of 7 kSamples/s (corresponding to a final net rate of 84 kbps) with
a percentage of lost frames below 4%. It was also shown that the system supports simultaneous
communication of three sensor nodes at 3 kS/s (36 kbps) each, with a percentage of losses of
less than 4%.
Keywords:
Body Area Networks, BAN, Zigbee, 802.15.4, Electronic Textiles, Tympanic Temperature.
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