Wireless Gateway

Type: Semester thesis
Students: Fabian Schenkel
Advisor: Clemens Lombriser
Project: e-SENSE

In the future, we will be surrounded by many different sensor nodes. Some are wearable and reside on our body, some may be arranged in our environment. As they have different requirements for example with respect to size and power consumption, different radio types will be used. Different radio types are not able to communicate with each other, unless there is a gateway present in the network. This was the motivation for this work.

A Wireless Gateway has been designed, built, and tested. A IEEE 802.15.4 (ZigBee), a Bluetooth, and an ANT radio have been integrated. This allows to communicate for example with Tmote Sky sensor nodes, with the SensorButtons designed here at the wearlab, and Bluetooth devices like Laptops, PDAs, and Phones. A serial link to a PC can be established through an USB connection. The board can be powered by USB or by using a li-ion battery. A battery charger has been placed on the board to allow the charging of an attached battery.

TinyOS 2.0 has been ported as operating system to the platform. Drivers for all three radios and a gateway module that does the actual packet forwarding to the radios has been written.

Different evaluations have been made to test the performance of the Wireless Gateway. Measurements cover throughput and latency of the radios as well as power consumption of the board under different operating conditions. Radio latencies reside on average in the interval from 3.5ms to 13ms, depending on the radio. The achieved throughput lies between 10kbps and 20kbps. The nRF2401 and CC2420 low-power radios showed a current consumption of about 20mA, whereas the Bluetooth radio needs 130mA.