Print

HighWLAN: A Driving Wireless Network
Pages: 1, 2

Launching the HighWLAN

After stopping for the night at a cabin in central Ohio, we were ready for the final day of driving and a shot at wireless networking. Schwern and dha drove Meng's Volkswagen Passat with Schwern's laptop thrown in the back seat, running talkd. dha was the co-pilot for the Passat and assumed all communication roles for their car. Meng rode with me in my Hyundai Tiburon acting as communications officer and uplink controller.



After quite a bit of man handling, we managed to get everyone on the network. We had all sorts of odd, novice-like issues. First, we were using a Netgear Access Point that Meng had in his car. This didn't work out too well. Next, Schwern's laptop didn't have the proper essid set and we managed to get that working at a gas stop. Once those issues were resolved we had our laptops on the network and all was good. pings were returning and ssh connections were succeeding. Meng and dha connected using talk on Schwern's laptop and we spent a good 100 miles just finding things to talk about. That's what happens when you work hard to build something that's minimally useful.

Communications Officer's Post
In order for this rig to be truly functional, we had to have communication with the outside world. This was achieved by accessing the Internet through my patched-in cell phone.

After rambling on about movies, making fun of each other's driving and deciding where to stop for dinner we decided to connect our network to the Internet. After all, we needed to send out proof that this was working. Once my cell phone reached a state of moderately reliable service, Meng brought up the link. We logged on to IRC and bragged about our connectivity. We sent email stating our coordinates. We acted like little children on sugar highs.

Just then Meng got an emergency call from work and his services were needed online. Our network was needed, what a wonderful feeling. We were online for a solid hour, surely being passed from cell tower to cell tower. The link stayed up just fine. Of course, we eventually drove out of cell range all together and lost that link. The network continued to be useful, we used it to communicate needed stops for gas or bathroom breaks. It's a good thing too, what with Schwern's "expressive" driving.

Testing the Network

After hours of driving, we decided it was a good idea to see what conditions caused the network to fail. It had been working like a charm for most of the trip and as any tester will tell you, it's more important to know when it breaks, not when it succeeds. We decided to try a distance test first. Using the 200 foot markers on the side of the highway we gave ourselves an estimated 500 feet of distance and the connection was just as strong as ever. Then we slowly added distance and at an estimated 800 feet the connection broke down. We were very happy with that number, especially because it didn't represent Line Of Sight (LOS). The testing laptop had to acquire a signal through several cars in traffic.

Still later in the day we decided to stream MP3's from one car to another. I had an adapter that converted the tape deck to an audio-in jack that was connected to my laptop. Schwern's laptop was in the Passat and was capable of streaming mp3's using Apache::MP3. The streaming worked but the playback didn't because my XMMS was throwing a temper tantrum. All was not lost, however, we resorted to remotely controlling Schwern's laptop to play random songs in the Passat and there was nothing they could do about it.

There was one major problem that destroyed our network. If a large truck drove directly between us is creates the same effect as a careless backhoe discovering your fiber network. Those of you familiar with most of I-70 know that the geographical layout is just flat. Sure, there are a few hills but mostly it's just flat and bare. Because of this, when large, dense metal objects decided to drive between us there was nothing for our antenna's signal to bounce off of to reach the other car. Again, all was not lost. Thanks to the wonders of the TCP/IP protocol our connections were not harmed in any way, just lagged a little.

What Good Is It?

Related Reading

Building Wireless Community Networks
Implementing the Wireless Web
By Rob Flickenger

There are several answers to this question. The simplest answer is that it's just another incarnation of two way radios, cell phones, or GPS systems. Like two way radios the local network is free. That makes all the difference in the world. Like cell phones and GPS systems, it can be connected to other useful networks and resources.

When I explained this project to Adam Turoff he made a bold prediction. He believes we'll see the US military using wireless networks in the same manner. I giggle at the thought of secure transmission happening over ssh to a server in an unmanned plane but it could happen. I just want to be the first to know if they use IRC or talkd for their communication.

I'd like to see a few companies begin offering wireless kits for cars. With knowledge in the right areas, it would not be difficult to create a hands-free client with voice recognition and even cell phone hook-ups. I could do the software now with great Open Source speech programs such as Sphinx II for voice recognition and Festival for text to speech output. Tie them together with POE and my favorite programming language, Perl, and you there you go.

Last, I can't stress enough the importance of free, (mostly) unobstructed communication. The cell phone costs would have been very high. More troublesome than that is the service area on the open road. Our network was up 99%, the cell phone companies didn't do that well. As for the getting online with the cell phone, I'm just glad I had a credit built up because that was expensive.

Conclusions

I managed to create a lot of hype around this project. Some called me lame, some called me cool, but they all called me geek. All I know is that my friends and I made the most out of an otherwise boring all-day drive. Wireless networking has thousands of undiscovered applications with no end in sight. Do your part to uncover the useful bits.