Butch, Cellular isn't that expensive when you're talking a few cars... if you're talking 30 patrol cars... I agree it's expensive. Heck, if the city has a ton of cell phones already they might be able to get the service free. I've heard of cities getting aircard equipment to do network monitoring type work at night when the network was offloaded for pennies a month. I agree that Mesh is way beyond what most departments need.
Many police departments have two officers in their cars... so the second officer needs to be able to work on the laptop on the way to a call etc. Probably not a requirement here since it's a small town... but for instance one city I am working with now wants to be able to watch streaming video from security cameras while driving up to 75MPH... that's hard to do without a Mesh IMO. Also, I doubt that Homeland Security is paying for anything here or they wouldn't be hitting up Walmart for free laptops :-D For your last part... you didn't explain what you did for your network. What equipment was used, how it was configured, etc. I would suspect you ended up working around the 802.11 protocol to handle the roaming hand-offs better. It might not be a true mesh (meaning you have actual nodes meshing), but something similar must be done (more AP's than point to multipoint service to account for worse link budgets from omni's and typically NLOS shots). Generally it's also best to have the AP's below the trees... also kinda lends itself to a mesh. With that said... I'm not advocating any manufactures product here (I just happen to be the most familiar with Motorola's)... but if I was to build out a Mesh network, and mobility was required, I'd choose something that was designed for it and proven for it. Heck I'm really advocating air cards here... I've got no stake in that but realistically is probably the cheapest and best option for this police department assuming that there is decent 3G service there. Daniel White 3-dB Networks http://www.3dbnetworks.com >-----Original Message----- >From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On >Behalf Of Butch Evans >Sent: Saturday, October 17, 2009 12:55 PM >To: WISPA General List >Subject: Re: [WISPA] Ideas on Police Department Wireless Link from >Station to Cruiser > >On Sat, 2009-10-17 at 11:45 -0600, 3-dB Networks wrote: >> IMHO, the only way to do something like this where the office is >mobile is >> with cellular service > >I have done this MANY times without cellular and without mesh. Cellular >is too expensive and WAY too slow to be really very useful. Mesh is >simply not needed for what MOST of them need. > >> or to use a Mesh network designed for mobility (since 802.11G tends to >fall >> apart past 30MPH or so). > >You are thinking that an officer of the law is gonna be using the >network while driving at 30MPH+? If their need is to have it working >that way, then I would agree that it may be necessary to increase >coverage. > >> Unless this city want's to make a major investment in Mesh... I'd tell >him >> to stick with the cellular air cards (Verizon, AT&T, whatever) and be >done >> with it. > >In some cases, these networks have been paid for with Homeland Security >$$. No cost to the city. > >> Hacking together a solution is probably more effort than its >> worth, and there could be theoretical consequences if the network >doesn't >> operate correctly. > >Of course. It's all about explaining benefits and pitfalls. Once the >network needs are known (which they are not at this point), THEN a >solution is devised. > >For what it's worth, the second time I did this type of network, we >watched a LIVE streaming video from one cop car as it drove all over >town without more than a 1 second hiccup (which happened 2 times). >Additionally, he was talking to us via an 802.11g wireless voip phone >and NEVER lost the call. This was using a mixture of 2.4GHz 802.11b, >802.11g and 900MHz (Mikrotik 802.11a I think), if you're interested. >Not too bad for not having purchased, or even considered Moto. I think >to dismiss a technology outright before understanding what good >engineering can do is pretty short sighted. > >-- >******************************************************************** >* Butch Evans * Professional Network Consultation* >* http://www.butchevans.com/ * Network Engineering * >* http://www.wispa.org/ * Wired or Wireless Networks * >* http://blog.butchevans.com/ * ImageStream, Mikrotik and MORE! * >******************************************************************** > > > >------------------------------------------------------------------------ >-------- >WISPA Wants You! Join today! >http://signup.wispa.org/ >------------------------------------------------------------------------ >-------- > >WISPA Wireless List: wireless@wispa.org > >Subscribe/Unsubscribe: >http://lists.wispa.org/mailman/listinfo/wireless > >Archives: http://lists.wispa.org/pipermail/wireless/ -------------------------------------------------------------------------------- WISPA Wants You! Join today! http://signup.wispa.org/ -------------------------------------------------------------------------------- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
