Wireless Multimedia Sensor Networks

Testbed

We deployed an experimental testbed at the BWN-lab based on currently-off-the-shelf advanced devices to demonstrate the efficiency of our newly developed algorithms and protocols for multimedia communications through wireless sensor networks. The architecture of our testbed is as follows:

Architecture of the BWN-lab Multimedia Wireless Sensor Network Testbed

Our laboratory has a sensor network testbed with 6 imotes from Intel and 50 micaz scalar motes from Crossbow. We plan to increase the number of micaz sensors in order to deploy a higher scale testbed that allows testing more complex algorithms and assess the scalability of the communication protocols under examination.

The testbed includes three different types of multimedia sensors:

  • Low-end imaging sensors

  • Medium-quality webcam-based multimedia sensors

  • High-end pan-tilt cameras mounted on mobile robots

Low-end imaging sensors such as CMOS cameras can be interfaced with Xbow's micaz motes based on the Cyclops platform. Cyclops is an electronic interface between a CMOS camera module and a wireless mote such as MICA2 or MICAz, and contains programmable logic and memory for high-speed data communication.

The medium-end video sensors are based on Logitech webcams interfaced with Stargate platforms. Stargate is a high-performance processing platform designed for sensor, signal processing, control, robotics, and wireless sensor networking applications.

The high-end video sensors consist of pan-tilt cameras installed on a robotic platform. The objective is to develop a high-quality mobile platform that can perform adaptive sampling based on event features detected by low-end motes. The mobile actor, as we call it, can redirect high-resolution cameras to a region of interest when events are detected by lower-tier, low-resolution video sensors that are densely deployed.

The testbed also includes storage and computational hubs. These are needed to store large multimedia content and perform computationally intensive multimedia processing algorithms.

44 MICAZ motes equipped with whip antennas and placed in a rectangular grid formation.

  

6 Intel Imotes with Bluetooth radios forming a tree shaped scatternet. (Courtesy of Lama Nachman at Intel Research)

 

Acroname GARCIA, a mobile robot with a mounted pan-tilt camera and endowed with 802.11 as well as ZigBee interfaces.

  

GARCIA deployed on the sensor test-bed. It acts as a mobile sink, and can move to the area of interest for closer visual inspection.. It can also coordinate with other actors and has built-in collision avoidance capability.

 

44 MICAZ motes equipped with whip antennas and placed in a rectangular grid formation.

  

STARGATE based multimedia sensor interfaced with the MICAZ sensor testbed. This allows for video monitoring through the camera-STARGATE interface and communication to the sink through the on-board sensor mote or independently linking with a laptop through the 802.11 card.

 

 

Animation of WSAN Testbed Experiment

This is an animation of Multimedia Wireless Sensor Network experiment that we did with the above mentioned hardware. In this animation there is a robot with a camera on, one on the bottom left. There is a laptop which sends the program to robot which is equipped with arm processor running embedded linux. This arm processor is running a database and collecting data from the sensors (blue transmitting things). A program is running on the arm which keeps querying the database for any values higher than a threshold. If there are any it sends the robot to that node and sends the picture back to the pc. If there is another node above the threshold than it goes back to its initial position and than to the node in question.

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