| William H. Magill on 25 Nov 2004 05:28:02 -0000 |
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On 23 Nov, 2004, at 11:38, George Gallen wrote: Will this system work like cell phones? No. Not even close. By comparison, cell phones work extraordinarily well. By that I mean, if you are moving, and jump from one AP to another, will your IP address change? It is theoretically possible to build such a system, however, from the way The Committee has been talking, not likely. Since the City will NOT be providing ISP services, whoever the ISP for any given AP will control what IP you get and where, if anywhere, they allow roaming. I looked at this to be nice if you were on your way to school or work, using public transportation, you could maybe get some work done, but if your IP address changes every block, it would be really difficult to maintain any connection that is IP dependent. Ignoring the fact that there may not be much public transportation in the City in the future, WiFi roaming is not particularly "good" for maintaining something like an ssh connection for example. Not that it can't be configured to support it, but it works much better (i.e. requires much less network "technical administration") with anything that is stateless -- like an HTML connection, that doesn't care if the IP changes. WiFi is really intended for "static" usage. While you can provide coverage for a large, congruent, open area (like Rittenhouse Square) providing coverage the length of Chestnut Street takes a LOT more effort. In the end it will all depend upon who the ISP is, how many ISPs are involved in the system and if they decide to offer roaming. Without a lot of expensive antennas, RF radiates in a 360 degree circle with signal strength dropping off the further you get from the AP. In order to remain "unlicensed" the signal strength of an AP is miniscule compared to a Cell transmitter. Similarly, the sensitivity of the AP receiver is much less than that of a Cell receiver because of the correspondingly significantly lower cost. Initially I saw this system to great for the above situation, but now....not sure. Yeah, that's another of those "expectations" that the public has, which The Committee most likely won't include in the RFP. T.T.F.N. William H. Magill # Beige G3 - Rev A motherboard - 768 Meg # Flat-panel iMac (2.1) 800MHz - Super Drive - 768 Meg # PWS433a [Alpha 21164 Rev 7.2 (EV56)- 64 Meg]- Tru64 5.1a # XP1000 [Alpha EV6] magill@mcgillsociety.org magill@acm.org magill@mac.com whmagill@gmail.com
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