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Wireless Everything at Dartmouth
hende_jman writes "Dartmouth College in Hanover, New Hampshire is condensing its phone, cable TV, and Internet services all into Wi-Fi, as reported by the New York Times (free registration required). The project, which started in 2001, has added 1400 WAPs and 24,000 wired ports. All that, and cost effective too."
My brother went to Dartmouth in 1993, and they required everyone to have a computer as they already had campus-wide "blitz mail," which was used a bit like IM. All their assignments were handed in via email, class cancellations were broadcast that way, etc. Everyone was on it.
Meanwhile, I was at Florida State in Tallahassee, where it wasn't until probably 1995 that you could even easily get a university email (we used to have to set up free city accounts at the public library, which we could then access from campus).
I don't know that it made much of a difference in his education, but he loved the wow factor and I'm sure that's at play here, too.
...and I work at the helpdesk, no less. I've beta-tested the VOIP rollout and supported the rest. My personal opinion is that the wireless network will NOT hold up well under heavy load once all these services go into widespread use. As it stands now, things slow to a crawl during finals, etc, when people swarm the library and the APs. This is, after all, an 802.11b campuswide network. The backbone is there, but I don't know how the APs will deal with all these latency-sensitive streams. Side note: they've been promoting the VOIP option in the media for months now, but students aren't allowed to get extensions. A little disingenuous, no? Hell, I'd just be happy if the "100% coverage" actually ever gave me a signal in my room. There's some content, and prospects, for this--but so far, it's just PR-fluff.
Yes, if the multicasting is done correctly.
The short answer is that you don't actually have to multicast all twelve billion (slight exageration) channels simultaneously all the way to the set top boxes, just whatever 12 channels the people on the LAN are using (looking at this from the POV of a residential cable system based on Gig-E fiber to the home). If this is done inteligently, you can multicast only those channels being viewed and use IGMP snooping to figure out what to start multicasting from the cable head end. Depending on the exact network configuration (PON, active, etc), the multicast pruning might be done in the network, in the CPE, etc.
As for bandwidth, yes, it does matter what codec you use, but MPEG-2 for standard resolution TV is 4-6 MB/sec (IIRC). HDTV is another matter entirely, as it's huge (especially when uncompressed).
I'd write more, but it's time for lunch.
Digital cable and statelite typically use 2-2.5mbits for SD programing. With proper multicasting, QOS, large frames, you could probably get 500mbits onto GigE without trashing the network, giving us 250 SD channels.
HD mpeg2 needs about 18mbits, and HD divx needs 10-12mbps. I believe DVDs run at 4-5 mbits, and the quality is better than digital cable or satelite.
The copper is actually short, less than a mile, less than 1000ft in many cases. They use HFC, hybrid fiber/coax. It's fiber nearly until it gets to you. What's more, it's heavily insulated/shielded coax, and has alot more bandwidth than the standard telco loop.
Contrast this with a telco loop which can be 5+ miles of unshielded copper.