Quote:
Originally Posted by Railgun
I think you're doing yourself a disservice there by saying it's not about coverage. It absolutely is about coverage. Take ANY wireless site survey and what do you see? A coverage heat map. Most office environments aren't THAT high density in terms of people. And if they are, there still aren't that many devices other than mobile phones which won't be consuming the bulk of traffic at any given time. Of course, you'll have laptops, but most of the time, they'd be docked. Your highest concentration of wireless in this case would be a conference room. Do you see multiple APs in the ceiling there? No, as you have plenty of coverage in that location and the AP will handle the density as well. Of those, some will be on a corporate network, but many more will be personally owned devices and on a guest network. A single AP can handle multiple devices relatively easily, but as you point out, those mobile devices can't reach the levels of TX power the APs can, so your AP density increases to...increase coverage.
It's all about the environment in which the service will be deployed. That in itself will dictate whether you can get away with a single AP (SOHO or residential) or multiple (larger corporate environment).
Mesh networks are even worse for performance as they cut available bandwidth even further. The further downstream an AP is from the main AP, the more latency and reduction in available bandwidth to clients on that AP exists. If possible, always hardwire an AP.
In my last house, I was able to easily get away with a single AP. One, it was an old house that I'd rented, and couldn't wire anything and two, I didn't need to worry about it. My house that I'm in how was properly wired and I'm running five APs, two outdoor and three indoor. I need another one indoor as I don't have the coverage required in one area of the house. Has nothing to do with density.
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And I think you're doing yourself a disservice by following the old model of coverage. It is all about services/density of clients. When you look at heat maps, it's to determine boundaries of when APs start to conflict with each other. A proper wireless system will have the ability to monitor RF output of each AP and adjust transmit levels to prevent one AP from clobbering the other. This reduces the association issues between client devices and APs. Along with reducing "friendly fire" interference.
Your example of a conference room is extremely limited. In a single conference room, the fact there is a single AP placed there means that the wireless engineer understands the potential concentration of wireless clients in that room. Hence that AP is to service that location instead of having neighboring APs pick up the load. I also assume you've never done a wireless deployment for a large conference held at a large hotel/resort venue. I guarantee you won't be seeing a single AP supporting 300+ attendees.
Your assertion of a single AP handling multiple devices again is too general. Yes, APs can handle multiple devices. But there is a practical limit based on the network traffic it is handling. Some of the APs I've had experience with can handle 50 wireless clients. But that is for non consistent wireless traffic such as web surfing. When you throw on multicast traffic such as video streaming or latency sensitive communications such as VoIP/teleconferencing, that number drops to 15 to 20.
Your example of your home is an example of a limitation of the wireless client in transmit power. This isn't a situation where "coverage" is the problem. Is a situation of dealing with the weak power transmission of mobile devices. You placing an AP at that location is more to deal with the reception issue of the particular device. The false premise of blasting as hot a signal you can from an AP or wireless router has fed into the problem everyone is experiencing with 2.4 GHz networks. The issue of adjacent RF interference. Because of the limited number of non-overlapping channels available for 2.4, you run into constant situations where people are complaining they're having wireless problems even if their device is sitting right next to the AP/router. The move to 5 GHz is to get away from this RF interference issue as there are more non overlapping channels available. But even 5 GHz is starting to see interference problems with more and more devices making the move for more channel space and due to the move to 802.11AC. This is why a new IEEE standard is being worked called 802.11ad which proposes to use 60GHz as the carrier frequency. The premise is again not about blasting a signal as far as one can. But to have localized high speed microcells which won't cause all these interference problems.
On the topic of wireless mesh networks, yes, I know about the halving of available bandwidth per hop. But these topologies are way better than the garbage range extenders being used by many to solve a reception problem from wireless clients. The wireless mesh systems I see being used in corporate systems use 5 GHz as the backhaul and 2.4 GHz for client connectivity. This eliminates the issue you've pointed out.
Since we're talking about home networks, my home network at one point had 4 different wireless solutions running at once: Aruba Networks controller based, Aruba Networks IAP, SonicWall, and Aerohive. I have since pulled the IAP and Aerohive systems offline. The Aruba controller based system is running a 7008 controller with 3 AP225, 1 AP215, and an AP105 for RF spectrum monitoring; this system is broadcasting 3 SSIDs. I also have a RAP3 I take on travel with me which establishes an encrypted layer 2 GRE tunnel back to my home network that allows me to extend my wireless at home to any location through the Internet.