AP proximity? (How close can your AP be to someone else's AP).

Question

Tried doing some searches but cannot find anything...
If you are designing a WiFi system in a building that already has a system (independent to your new system), how much separation between APs should you have? ie. How close can/should you put your AP to an existing AP?
Sometimes because of the building layout you want to go at the same spot, but I know you need some separation. Assume omni, 100mW APs.
Thanks.

Answer 1

You have some valid points. But every-man-and-his-dog has a 2.4 AP and it still works then it will most likely still work even if it's "every-man-and-his-dog +1".
Most importantly the system has to be designed correctly regardless of the existing networks. The better your system is designed to work solo, the better it will perform in an environment with other APs. Yes existing networks will obviously degrade your performance, but you can't really find anywhere in an modern urban environment without seeing a dozen APs from either inside and/or outside your building. The existing network could be dense but if it is not used all that much, the degradation should not be extreme.
Besides, you have say 100 users in the building, they can use system A (existing) or B (my new one). If they have the option of using both/either, then you have 50 on A and 50 on B. Is that much/any worse than having 100 on A? Contention is contention though the extra beacons will add to it. For the users that can only use "B", then they will at least have an option, even though it will be at a slower performance than if A did not exist, at least they have an wireless option now. If "A" did not exist, you could build your "B" network, and 1 week later, someone could build "A" anyway.
1) Don't worry, it's not my money. Most of the existing "high density" areas are low usage private wlans. (P.S. What's the definition of "high density"?).
2) RFID is not part of our application.
3) & 5) This is being accounted for in our designs.
4) If we use Cisco, then I hope it's significant. ;-)
6) Gigabit.
Good discussions.