For my latest project, I need to have a PC communicate with an Arduino that is going to be relatively far away, up to about 150 feet cable length or a 75 feet straight line if I were to communicate wireless.
We won't be able to boost the signal anywhere in between, if it needs to be done we'll have to do it either at the PCs end or the Arduinos end, or both ends. To make matters worse we're going to be in a noisy environment too..
Communication needs to go both ways and must obviously be reliable. Speed is less important, even 2400 baud would be okay, altho 9600 would be nice for fast response times. But data integrity is the most important thing here.
As far as I understand, communicating anywhere over 16 ft using a plain USB cable is not going to work so I guess we can scrap that right away.
USB over CAT5/6 looks pretty interesting and from the sound of it it would handle distance too. But I have no experience whatsoever with it, it definitely sounds like the easiest solution.
RS232 would work probably work fine too if we could get a real RS232 connection over a CAT6 cable, I'm not so sure about TTL and its low voltages, but again no experience. The PC doesn't have a real RS232 port so we're stuck with either having another Arduino there or a USB-serial adapter, and neither of those give a real 12V serial signal. That can be solved with some circuitry but I would ideally want to use as little parts as possible to keep the clutter down.
Wireless might be a problem because we're in noisy environment, and there will be lots of cellphones and what not around too. On top of that it'd probably be the most expensive solution.
What do you suggest would be the best way to do this?
Thanks in advance

Edit: I should add that the Arduino will have its own power supply and does not need to be powered by USB.