How do I transmit voice using Wi-Fi in an Ad-hoc networking mode?

Question

We are looking to create Inter Vehicle communication system. So, a couple of vehicles should get connected automatically and could be able to share voice. We decided to implement Ad-hoc networking using Wi-Fi. We are expecting it to cover a radius of 100 meters.

1. If we could create a system like this.. and one of the user sends a voice information, does all people in the network get that ?

2. What are the things we require to get this project done ?

Answer 1

I think Wi-Fi is a spectacularly bad choice for this application.

Indoor isotropic/omnidirectional Wi-Fi gear coverage with unobstructed line-of-sight is usually less than 50 meters. To reach 100m reliably in varying outdoor conditions between moving vehicles using omnidirectional antennas, you'd probably need to add an amplifier to get from typical Wi-Fi equipment's 0.3 - 1.0 Watt powers, up to something like 10 Watts, maybe more. But you'd have to use a good amp so it doesn't distort the signals or add noise.

Even when you get the physical layer and data-link layer problems solved, you'd still have network (IP) and application (voice software) layer problems to work out.

Answer 2

So, I'd agree with Spiff that WiFi is probably going to be a fail for the conditions you're talking about. I have no brilliant insight into a full on solution for what you want, unfortunately.. but I would suggest that you look into the Serval Project.

The Serval Project is an Android software project that creates a mesh-network between your phones which allows you to dial them (with their numbers) and talk (obviously); without any carrier/etc network backing you up (just the ad-hoc mesh network between the phones).

It is however a research/prototype project, and not release quality.

I've never tried it but I would be very tempted to if I had some phones I didn't care about too much. One thing that scares me is their disclaimer that "Serval may permanently alter or damage the software or hardware on devices upon which it is installed."! I'm not sure if that's simply to cover their butts or a real concern.

It's a very interesting project and I'll be all over it if it can reach a more refined state. Their project site is: http://www.servalproject.org. You can also find it on the Android Market.

But remember, it is at an early stage (prototype) and doesn't sound to be particularly reliable, and it seems to have many bugs and incompatibilities. Read the disclaimer on their project site, and look for reviews on the market, discussions, etc.