This study is included in a critical healthcare monitoring system, where there is the need to assure that within a Body Area Networks (BAN), all the information coming from the devices is fully delivered on time to its destination. The communication between the different devices used in this system is established by Bluetooth. This technology uses a frequency band that is nowadays widely used by other technologies such as Wi-Fi networks, microwave ovens, cordless phones, etc. On such a busy medium, it is unavoidable that collisions will occur, leading to the delay/loss of information. In order to confirm the sturdiness of this connection, and within the context of the project, we evaluated the extent to which possible interferences could damage the link, creating delay/loss of information on these communications. For that purpose, we developed software that allowed us to test the different stages of each experience in the laboratory, recreating realistic scenarios. We tested the way in which Bluetooth communications reacted when established on a medium crowded by the transmission of several Wi-Fi devices, and also when close to an operating microwave oven. Our results show that Wi-Fi and microwave ovens interfere and affect Bluetooth communications. This can be seen by the resulting packet delay values and by the average time of data transfers. Transferring the same file with interference took approximately twice the time it took without any source of interference. These results also show the intensive use of coexisting mechanisms and also the resilience of a Bluetooth link.
Author: André Pereira
Type: MSc thesis
Partner: Instituto Superior de Engenharia do Porto