DEMONSTRATION

Configuration

The demo consists of 4 laptops, whose basic configurations are as follows:

Model	IBM T23
CPU /Memory	Intel Pentium III 1 GHz / 384 MB
Operating system	Redhat Linux 9, Kernel ver 2.4.32
802.11 NIC	EnGenius 2511 CD PLUS, PCMCIA
802.11 Chipset	Intersil Prism 2.5

There is Video Server (i.e. Transmitter), Video Client (i.e. Receiver) and two candidate helpers. The two helpers offer different transmission rates for the two hops as mentioned below:

Name	First Hop Rate	Second Hop Rate
Fast Helper	11 Mbps	11 Mbps
Slow Helper	5.5 Mbps	5.5 Mbps

Demo Description

The transmission of a video clip is considered in the described testbed. A VLC server is placed at the source station and constantly streams a commercial video clip, while the destination station runs a VLC media player to play the video. The demo consists of three sequential phases, as outlined below:

Phase 1	Both helpers are active. The transmitter selects the Fast Helper and transmits through it. The quality of the video at the receiver is superior.
Phase 2	The wireless card of the Fast Helper is turned off. The transmitter dynamically understands the change and switches to the Slow Helper. The quality of the video at the receiver is still good.
Phase 3	The wireless cards of both the helpers are turned off. The transmitter now transmits directly to the receiver in a low rate. The quality of the video at the receiver degrades appreciably.

As described in Table above, the user perception is poor for video transmission in the 802.11 network, as noticeable freezes and distortions occur frequently. Meanwhile, the video is smooth and artifact-free, when it is received over a Cooperative MAC network. Figures below provide a snapshot of the video taken at the receiver for 802.11 and Co-operative MAC, respectively. The comparison of these two figures is typical and reveals the substantial improvement in the video quality that CoopMAC can deliver.

Graphical User Interface (CoopGUI)

To facilitate experiment configuration and simplify user participation, a graphical user interface (GUI) called CoopGUI has also been developed. Based on Java SDK 1.4, CoopGUI communicates directly with the driver of 802.11 and CoopMAC, and obtain the corresponding state information and parameters such as the ID of every station (MAC and IP addresses) and the transmission rates the station can sustain. At the transmitter, the CoopGUI displays the content of CoopTable, such as the active candidate helpers, and the helper that is being used currently. At the helpers, the GUI gives information about its state (on or off) and if helping which station it is helping. We don’t run the GUI at the receiver, as the main point there is the quality of the video that is observed in the VLC client. Using the GUI we can also dynamically change several parameters in the driver, such as the rates in the two hops for every helper, the Hello Packet period, etc. Below is a snapshot of the two different windows of transmitter’s CoopGUI (i.e., Basic window and Configuration window):

You can watch the whole demo in action by clicking on the folowing picture. You will be able to watch a video of the four laptops' screen while the demo is active. Requires Windows Media Player.

	Demo in action

Demo 2 (April 2006)

In this Demo we psesent the whole functionality of the CoopMAC through the set up of the photo. We use four laptops: The Video Server is streaming video to the Video Client and the Video Client is playing the video. There are two candidate helpers: The Fast Helper and the Slow Helper. The two helpers offer different transmission rates for the two hops (the rates are depicted in the photo). During the demo, the helpers turn their wireless cards on and off in a periodic manner. The Transmitter (Video Server), updating dynamicly its CoopMAC table, realizes the existance or not of candidate helpers and chooses dynamicly the best avaliable helper. If there is no helper avaliable, the server transits to the client directly (using IEEE 802.11 with a slow conneciton of 1 Mbps).

	Demo Setup

You can watch the whole demo in action by clicking on the folowing picture. You will be able to watch a video of the four laptops' screen while the demo is active.

	Demo in action

Demo 1 (December 2005)

In order to demonstrate the efficiency of CoopMAC we set up a demo using the testbed of the photo. We broadcast a video clip from the server to the client and we observe the quality.

We use two setup:

CoopMAC Setup	802.11 Setup

Video frames at the receiver with and without cooperation:

CoopMAC Setup	802.11 Setup

You can watch the whole video at the receiver with and without cooperation:

Video 1 - Cooperation

Video 2 - No Cooperation

 

*In order to watch the video you need the Windows Media Player.