[teacup50]

Unless you have lead walls, a ~1000 sq ft apartment should be fully covered by a single access point.

The problem in NYC is that there's just too much band crowding; adding more access points is only going to provide an improvement (if any at all) until everyone else does it, too, and then it's going to be worse for everyone.

We really need better solutions for extremely high-density deployment of competing WiFi networks.

[mikeyouse]

Unfortunately, it doesn't take lead to attenuate WiFi signals. Many turn-of-the-century buildings used chickenwire under plaster on the interior walls. This makes a pretty effective Faraday cage:

http://www.wsj.com/articles/SB126221116097210861

My SF apartment is the same -- well under 1,000sqft, need an enterprise router and a substantial repeater to get signal on the end opposite from the cable modem.

[acdha]

It's not just old buildings, either – at a previous employer we learned that a lot of the interior walls had a similar mesh inside. You could put a Cisco AP set to the highest power levels on one side, move a laptop one foot away on the other side and barely be online. We solved that by adding extra APs, which wasn't a big deal since we had the budget and plenty of Ethernet drops but in a residential building - especially a rental - that'd have been an annoying amount to pay.

[stordoff]

My house, built <20 years ago (UK), has something similar. Currently at 4 APs (DD-WRT routers acting as APs, all hardwired to a central router), and still some rooms only get a patchy signal (fortunately we're more than 50ft on all sides from other building, so not too concerning about interference). 5GHz is even worse - for any practical use, it's pretty much limited to a single room per router.

[jburgess777]

Going 5Ghz is definitely a step in the right direction. Not only does it provide greater bandwidth for more channels but the reduced range actually helps avoid interference.

The downside is that you might need more access points to achieve equivalent coverage. Forming a mesh, like these Google APs do, is useful for avoiding additional wiring.

The beam-forming features present in 802.11n and 802.11ac also help reduce interference.

[sbierwagen]

  The problem in NYC is that there's just too much band crowding

802.11ad will help there: runs on 60GHz. Certainly won't penetrate drywall. https://en.wikipedia.org/wiki/IEEE_802.11ad

[peterbonney]

The walls may not be a primary problem, but they do contribute. The simple test (which I've done) is to stand either side of a wall and check the signal. With an unobstructed line of sight to the router the signal is acceptable; on the other side of the wall the signal is poor (dropped ping packets, high latency, etc.). I doubt it's because of the additional 1 foot of distance from the router.

But to your point, I'm sure it's all interrelated and if I had concrete walls with no neighbors it would be significantly better.