City wide coverage?
in [Wireless Internet]
|
Prev: Got the Cisco E3000
Next: Used Gear...........
From: Tony Hwang on 27 Apr 2010 01:52 SteveC wrote: > How do large companies typically offer wifi coverage for a > large city such that no matter where you are, you can pretty > much connect? > > Is this done by multiple antennas, high power APs, what factors > are involved. Hi, Maybe via the bird in the sky?
From: ps56k on 27 Apr 2010 02:38 "SteveC" <SteveC(a)gmail.com> wrote in message news:hr5rge$4qu$1(a)speranza.aioe.org... > How do large companies typically offer wifi coverage for a > large city such that no matter where you are, you can pretty > much connect? > > Is this done by multiple antennas, high power APs, what factors > are involved. search on things like - metro wifi -
From: bod43 on 27 Apr 2010 07:48 On 27 Apr, 07:38, "ps56k" <pschuman_no_spam...(a)interserv.com> wrote: > "SteveC" <Ste...(a)gmail.com> wrote in message > > news:hr5rge$4qu$1(a)speranza.aioe.org... > > > How do large companies typically offer wifi coverage for a > > large city such that no matter where you are, you can pretty > > much connect? > > > Is this done by multiple antennas, high power APs, what factors > > are involved. Cell phone infrastructure has to solve the same problem. They use high power APs and quite a lot of them. Here is one in London. http://www.sitefinder.ofcom.org.uk/ postcode N1 8LN Name of Operator Orange Operator Site Ref. GLN0044 Station Type Macrocell Height of Antenna 17.2 Metres Frequency Range 1800 MHz Transmitter Power 29.6 dBW Maximum licensed power 32 dBW Type of Transmission GSM I am not exactly sure what 32dBW means (well I know the acronym and some maths) but I am sure it is a LOT more than is typically allowed for WiFi transmitters. http://sss-mag.com/calcdb.html 29.6 dBW = 912 Watts
From: Jeff Liebermann on 27 Apr 2010 19:18 On Tue, 27 Apr 2010 05:08:30 +0000 (UTC), SteveC <SteveC(a)gmail.com> wrote: >How do large companies typically offer wifi coverage for a >large city such that no matter where you are, you can pretty >much connect? > >Is this done by multiple antennas, high power APs, what factors >are involved. <http://www.muniwireless.com> <http://en.wikipedia.org/wiki/Mesh_networking> Sector or omni antennas, 4-12 access points per square mile, mesh networks or expensive backhauls, creative billing and advertising, etc. High power sucks, but is all too common. I really don't want to explain all the various "factors". Good reading would be the literature from the major players and vendors. There are also complete system proposals and templates available online, some of which are great science fiction reading. Also the National Broadband Plan has some aspiration towards universal connectivity. Also note that wide area networks are being planned and built using WiMax and LTE on newly auctioned licensed frequencies which have the potential of being far more reliable than 2.4GHz unlicensed. If this is your homework project, you should be able to use the above as a starting point. -- # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060 # 831-336-2558 # http://802.11junk.com jeffl(a)cruzio.com # http://www.LearnByDestroying.com AE6KS
From: Jeff Liebermann on 28 Apr 2010 14:03
On Wed, 28 Apr 2010 05:35:55 +0000 (UTC), SteveC <SteveC(a)gmail.com> wrote: >Why do you think high power "sucks"? Two big problems (and some minor ones). 1. High power access points talk farther than they hear. If the connecting radio (i.e. laptop or PDA) also had a high power xmitter, there would be no issue. However, with a high power AP, the excess power simply creates interference to other systems and cells. The effect is also known as the "alligator" which is an animal that has a big mouth, and small ears. 2. Mesh networks tend to use omnidirectional antennas. Lots of reasons but the big one is that it creates a "cell" type of coverage. For 2.4GHz, there are only 3 non-overlapping channels (1, 6, 11). If the xmit range of any cell substantially overlaps an adjacent cell, and the system re-uses channels (very common), then there's going to be interference. With high power AP's, most of the interference comes from the systems own transmitters. 3. There are other reasons but I'm late for lunch. >Shouldn't everyone be >able to have a wifi broadband connection? That's what the National Broadband Plan suggests. There is nothing about high power in the plan. >I was just wondering how it is that no matter where I point >my parabolic reflector antenna, I am able to connect to a >certain company here. I can't answer that without technical details. The company many be rather close to you, your dish antenna may be so small as to leak in odd directions, the company may have multiple AP's with duplicated SSID's, etc. -- Jeff Liebermann jeffl(a)cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |