What... I never said 4.9GHz doesn't work past 30MPH. I know for a fact it does
What I said is that to assume you put a 4.9GHz AP on a tower in the middle of town and that's going to do it is very short sighted. The EIRP rules in 4.9GHz are not great... and physics is going to prevent you from penetrating tree canopy and houses. Furthermore... point to point operations are the primary use of 4.9GHz spectrum, not point to multipoint. There are lots of politics with the spectrum also... for instance what happens if the county moves in during an emergency and wants to turn on their 4.9GHz gear... usually they get priority and you have to shut off your network. That's why 4.9GHz is not great for mobility... UNLESS your deploying a Mesh. I probably should have specified better ;-D Even then... if the noise floor is low enough... 900MHz and 2.4GHz may be better solutions for signal propagation... Daniel White 3-dB Networks http://www.3dbnetworks.com >-----Original Message----- >From: [email protected] [mailto:[email protected]] On >Behalf Of Scott Carullo >Sent: Saturday, October 17, 2009 12:57 PM >To: WISPA General List >Subject: Re: [WISPA] Ideas on Police Department Wireless Link from >StationtoCruiser > > >You must think the wireless carriers defy physics is you don't believe >you >can deploy any solution yourself that can't go over 30MPH. Why would >your >4.9 not work over 30MPH. > >Put one good set of equipment on a tall tower with no noise and you are >home free. Actually I'd put two sets on the tower for redundancy but >you >get the picture. > >Of course, it does depend on the environment as far as mountains, >tunnels, >forests, large tall buildings etc - I have no idea on the area I'm just >suggesting it as an option to have unless it doesn't work - for some >other >reason that it can go 30MPH lol > >I promise it looks like the car is motionless then the radio wave >travels >near speed of light. > >Scott Carullo >Brevard Wireless >321-205-1100 x102 >-------- Original Message -------- >> From: "3-dB Networks" <[email protected]> >> Sent: Saturday, October 17, 2009 2:39 PM >> To: "WISPA General List" <[email protected]> >> Subject: Re: [WISPA] Ideas on Police Department Wireless Link from >StationtoCruiser >> >> Not for mobility it won't. 4.9GHz is great for point to point or >point >to >> multipoint... but if you want mobility... your back to a 4.9GHz mesh >to >make >> it work reliably. >> >> There is an alvarion 900MHz system that alvarion claims will work from >one >> tower in a situation like this... but without having touched it I >won't >> recommend it :-D >> >> It probably comes down to two things: >> >> 1) What are the throughput requirements >> 2) Is mobility required (mobility meaning driving around the city and >> staying connected) >> >> Either way... the most cost effective solution (especially if there is >only >> one or two cars on the force) is going to be utilizing some sort of 3G >> service. Mesh networks (and I should specify, Mesh networks designed >with >> high speed mobility in mind... some sort of proprietary protocol has >to >be >> used for the switching) are going to provide the best coverage at high >> speeds with the highest throughput... along with giving the city a >network >> it controls. >> >> If mobility isn't required... you could do more of a hotspot type >> solution... or a high gain omni on the car with some high gain omni's >on >the >> towers... but there would be no guarantee of reliable service >everywhere... >> >> Robert... no matter what make sure before you do anything that the >> expectations are clear, and that you have a contract written. If the >city >> doesn't like the way the network performs, you could have a serious >lawsuit >> on your hands (since it is a public safety application). >> >> Daniel White >> 3-dB Networks >> http://www.3dbnetworks.com >> >> >> >-----Original Message----- >> >From: [email protected] [mailto:[email protected]] >On >> >Behalf Of Scott Carullo >> >Sent: Saturday, October 17, 2009 12:23 PM >> >To: WISPA General List >> >Subject: Re: [WISPA] Ideas on Police Department Wireless Link from >> >Station toCruiser >> > >> > >> >I myself would look into 4.9 or other licensed spectrum. Then you >could >> >have gear on one tower and service the whole area... >> > >> >Scott Carullo >> >Brevard Wireless >> >321-205-1100 x102 >> >-------- Original Message -------- >> >> From: "3-dB Networks" <[email protected]> >> >> Sent: Saturday, October 17, 2009 1:46 PM >> >> To: "WISPA General List" <[email protected]> >> >> Subject: Re: [WISPA] Ideas on Police Department Wireless Link from >> >Station toCruiser >> >> >> >> IMHO, the only way to do something like this where the office is >> >mobile >> >is >> >> with cellular service (although he will need to VPN back to the >Police >> >HQ) >> >> or to use a Mesh network designed for mobility (since 802.11G tends >to >> >fall >> >> apart past 30MPH or so). >> >> >> >> 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. Hacking together a solution is probably more effort than >its >> >> worth, and there could be theoretical consequences if the network >> >doesn't >> >> operate correctly. >> >> >> >> I'm still nowhere close to being able to offload this... but down >the >> >pipe I >> >> know of a city that is replacing their MOTOMESH Solo network with >> >MOTOMESH >> >> Duo... so those nodes would probably be cheap... and it allows the >cop >> >cards >> >> to go up to 144MPH in the Mesh and still stay connected (its >actually >> >really >> >> cool technology developed for the US Military... but the most it >can >> >do >> >is >> >> T1 speeds) >> >> >> >> Daniel White >> >> 3-dB Networks >> >> http://www.3dbnetworks.com >> >> >> >> >> >> >-----Original Message----- >> >> >From: [email protected] [mailto:wireless- >[email protected]] >> >On >> >> >Behalf Of Robert West >> >> >Sent: Saturday, October 17, 2009 9:05 AM >> >> >To: WISPA General List >> >> >Subject: [WISPA] Ideas on Police Department Wireless Link from >> >Station >> >> >to Cruiser >> >> > >> >> >I got a call Friday afternoon from the police chief of a small >little >> >> >spot >> >> >in the road asking about the possibility of connecting his >cruisers >> >to >> >> >the >> >> >station network via a wireless link. (He is the "Police Chief" >but >I >> >> >suspect he is also the entire police force) He said that the >local >> >Wal- >> >> >Mart >> >> >has agreed to donate to him a few of those little Acer 7" screen >> >> >laptops, >> >> >which are a big piece of crap from the number of repairs we've had >to >> >do >> >> >on >> >> >them... Anyhow, he wants to be able to be in the cruiser and >connect >> >to >> >> >the >> >> >network back at the station and use the websites from the Attorney >> >> >General's >> >> >office where he can run plates, drivers license info and also fill >> >out >> >> >his >> >> >reports. >> >> > >> >> > >> >> > >> >> >Here's the setup.. >> >> > >> >> > >> >> > >> >> >This Burg is a bit less than 2 miles long and about one and a half >> >miles >> >> >wide. The town hall is equivalent to a 4 story building and they >> >also >> >> >have >> >> >a water tower that looks to be 100 foot tall. The terrain is flat >as >> >> >can be >> >> >and they have the normal scattering of trees. The Town Hall and >> >water >> >> >tower >> >> >are the tallest structures by far aside from a large grain >elevator >> >> >right >> >> >outside of town. Boy wants to connect to his network anywhere in >> >town >> >> >from >> >> >his cop-mobile as well as when he is at home, also within the >town. >> >> > >> >> > >> >> > >> >> >We've done plenty of private networks but it's all been in the 2.4 >> >and >> >> >5ghz >> >> >band. He was thinking he could just throw up a 2.4ghz link and be >> >good >> >> >but >> >> >I told him to hold on, I didn't think he could broadcast the >Attorney >> >> >Generals network to every antenna in town, I had to do some >research. >> >> >So >> >> >this, because of my utterly blatant laziness, is my research. J >> >> > >> >> > >> >> > >> >> >Has anyone been down this path? What can we do and not do? >> >> > >> >> > >> >> > >> >> >I have a meeting with the guy next Wednesday and want to have some >> >idea >> >> >of >> >> >what we're up against on this one. (Hopefully he doesn't >recognize >> >me >> >> >as >> >> >the guy who took him to court over a ticket he wrote for a crooked >> >> >license >> >> >plate... I won that one by the way) >> >> > >> >> > >> >> > >> >> >Thanks for any help! >> >> > >> >> > >> >> > >> >> >Robert West >> >> > >> >> >Just Micro Digital Services Inc. >> >> > >> >> >740-335-7020 >> >> > >> >> > >> >> > >> >> > >> >> > >> >> >> >>>---------------------------------------------------------------------- >- >> >- >> >> >-------- >> >> >WISPA Wants You! 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