The main purpose of the sensing subsystem is to allow the testbed to collect and store sensor data from a variety of sources. Both fixed and mobile nodes are accommodated. As suggested by the image above, the mobile nodes can travel outside the testbed area while storing the sensor data and they deliver it on return. Handover (changing the point of attachment) is also supported.

For increased flexibility, several modules are defined as shown in the figure below:

• The client/server interface
• The client/server packet format
• The driver/client interface
• We developed several drivers