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Perhaps it is worth covering off some of the fundamentals of how Wi-Fi works.
Every Wi-Fi device on the planet is a transmitter and receiver combined - phone, tablet, laptop, printer, eftpos, Access Point (AP,) router, whatever - they all transmit and receive. Wi-Fi is a two way "conversation" like walkie-talkies not a one way "lecture" like television. Sound is a model to have in your mind.
The sort of Wi-Fi we mostly use involve a "client" device establishing a connection with some kind of fixed base station. This process is called "Association" in Wi-Fi speak and the base stations are called Access Points (or "AP" or Wi-Fi AP's (WAP.)) A SOHO "router" contains an AP along with all the other "get-you-on-the-internet" and "network-in-a-box" gubbins, but apart from the fact is shares a box, the AP in a "router" is no different to a stand alone AP.
Back to the conversation analogy - if two conversing peers cannot hear each other well enough to maintain a conversation then the need to either move closer together of remove obstructions (walls etc.) In Wi-Fi that either means moving closer to an AP (which is often inconvenient) or deploying more AP's closer to where we expect the clients to spend most of their time. On big sites we put up hundreds of AP's creating a "cellular" coverage pattern.
The "trick" with multiple AP's is how one established what I call the "backhaul" links (I'm not sure that's "official" terminology from the standards) between the AP's. The fastest and most reliable backhaul links are by using wired ethernet. Next best is probably by tunneling over the domestic mains using HomePlug type technology - though the performance is highly dependent on you mains environment. It is also possible to use Wi-Fi for the backhaul links, but that comes with increasing caveats. Of course, the AP's will need to be "in range" of a good signal from each other - if not speeds may drop. It used to be the case using "repeaters" that Wi-Fi backhauls clobbered the throughput (speed) but with things like tri-band kit and ever faster link rates (speeds) that may be less of an issue and of course even with repeaters, whether the bandwidth clobbering you suffer is a problem depends on your use case. It might be fine, but if you are speed obsessed you might want to avoid as much performance hit as possible.
The latest nonsense-du-jour being sold into the domestic market is so called "mesh" systems (sometimes styled as "whole home" and similar.) Many perceive this to mean "Wi-Fi backhaul" but it's not necessarily so. Many so called "mesh" systems can also use wired backhauls. IIRC there's one of them that will automatically choose wired/Wi-Fi backhaul depending on what's available, what's fastest and what achieves the best topology.
Unsurprisingly, this is the sort of thing that has been available in enterprise scale systems pretty much forever, and what mesh/whole-home et al is really about is bringing aspects of such enterprise systems to the domestic market where people are discovering "one AP in the middle of the house" cannot cut it. Most notably in mesh/whole-home system, the AP's "talk" to each other in meanginful ways to establish the backhauls and provide a single management platform - often an app, which doesn't happen with a fleet of stand-alone AP's/routers. The take home here is, don't assume that "mesh" means Wi-Fi backhaul - it probably does, but it may not be exclusively, you'll need to dig into the spec. sheets to see what you are getting. Unfortunately, "mesh" has become something of an overloaded term, not least since the marketing people have got hold of it. So do terms like "extender" which these days could mean almost anything.
With a fleet of multiple AP's/cells client devices can switch between them automatically - we normally call this "roaming." However there are some caveats: It is the client devices, not "the system" that determine if/when to roam. It is "Big Wi-Fi Myth Number 2" that clients are always "hunting for the best signal" - they do not and some clients need it to get pretty grotty before they initiate a roaming assessment. Even then, clients will only roam automatically between cells with the same SSID/passphrase, if not you have to flip them yourself or get sufficiently far away that you completely loose connection - which may be much further that you think.
Some newer Wi-Fi protocols and systems - such as the some of the newer "mesh" systems - have a kind of "hint" mechanism where the system can suggest to a particular client that is "might do better" using a different AP, though it's still up to the client whether it "takes the hint" and move (and not al clients are "hint" compliant and may simply ignore it anyway.) Part of the "deal" of mesh/wholehome/enterprise system is that the AP's talk to each other to establish which AP can hear which client the best and this between determine who can best service a particular client ans send them the aforementioned "hint." However, there's no mandate that anything calling itself "mesh" should offer such a feature, so one still needs to check the spec. sheet.
So answers:
1) No problem - on big sites we use hundreds - however if your "hubs" are routers, there's some things you need to do with DHCP to stop chaos breaking out - see the "using two routers together" FAQ pinned in this forum. Depends somewhat on what your "hubs" are.
2) Could be wired, could be Wi-Fi there's no mandate that it has to be either. Check the spec. to see what you've got. If possible, wires for backhaul are better than Wi-Fi, but with the right kit/system an AP may be no less a "mesh" node if it's on a wire.
3) Almost always more AP's is better - though you can go too far and get into issues devising a radio channel plan so adjacent cells don't interfere with each other - but that's a entire discussion all of it's own. If you have an AP in every room, you'd be in Wi-Fi Nirvana. Don't make the rookie mistake of placing the "AP's in the corridors" - sometimes it's unavoidable, but ideally you put your AP's where the clients are - the lounge, the den, the kitchen, the bedroom rather than the "communication" spaces and seldom used rooms - the hall the landing, the wet room, the lavatory. However, sometimes cost, geography, performance required dictate otherwise - it's something of a black art. |
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2-12-2019 04:45:31
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