Learning about Wireless Projectors

I have spent a lot of today looking at wireless projectors for a client. Some good learning which is worth posting here.

I have been both pleasantly and unpleasantly surprised by what I have found.

On the positive side, I was warned that the screen refresh/data transfer rate meant that the projector might be very poor at displaying the images from PC tablets using core subject software like maths and English activities or even graphics intensive presentation slides via the wireless connection. I found this not to be the case and was very impressed in the fast data transfer by wireless. Whilst it was not possible to transmit a movie satisfactorily, I did not observe delays of anywhere near a second for even the most data rich pictures.

On the downside, something that did not occur to me but should have, was the fact that the connection

Epson Wireless projector diagram

between the projector and the wireless laptop/PC tablet is via the single WiFi network interface card in the device. As all vendors are only across connecting in an “Ad Hoc” mode, this means that the laptop or tablet is connected to the school network or the projector but not both. I think that you can see a clear and obvious limitation in classroom applications where a student wants to share with a class what he or she is doing on the internet.

Given that I have been meeting with Audio Visual companies and not system integrators I was not surprised to hear that they had not really tried the projectors in an “infrastructure mode”. By this I mean in a mode where you can connect your projector to an organization’s existing wired or wireless infrastructure. If it is connected to wired infrastructure, the projector has a 10/100 Ethernet port with more bandwidth than any wireless connection could provide. If an Ethernet cable run is not feasible, the projector is put in Infrastructure mode, where it acts as a wireless client and connects to the wireless network specified. With either approach, the goal is to connect the projector to an existing network, which serves as the path over which the projector sends the screen images.

The student or teacher would then connect wirelessly to the network on which the projector is installed. He or she has installed the Projector Software Utility, which allows for selection of the projector, and the student or teacher’s screen is mirrored automatically. This more complex deployment lets clients simultaneously access other resources–the Internet and resources shared on the network, for instance–in conjunction with the projector, and also make presentations on the projector from anywhere on the network.

Whilst connecting the projector in infrastructure mode sounds like the solution that a school should be looking at, it does come with some challenges. Here are a few I can think of.

  • There is a potential that a clever and boisterous student might decide to connect to the projector in his least favorite teacher’s room and choose to broadcast a very inappropriate message on the projector.
  • In Ad-hoc mode the connection between the wireless device and the projector will be a dedicated 54Mbps. In infrastructure, the wireless device could potentially be sharing an AP with 20 other students. This might limit the data being sent to the projector to 2-3Mbps making it useless.
  • Given that the School that we are currently working with has up to 13 Wireless projectors being installed, this is going to mean a lot of projector IP addresses on the network. This is an issue for teachers and students looking to connect to the right projector in their room.

I am not sure of the right way to go here but I have shared this information with quite a few experts in my network so I lookforward to sharing the best advice I get and our experiences moving ahead.

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