I purchased 2 DCS-930L cameras and was disappointed the wireless range wasn't better.
I took one camera apart, located the internal antenna, then soldered in a 3db omni antenna (drilled the plastic case to run the coax through). My signal strength went from 29% to 100%.
I then took the camera and set it up in my backyard (about 80' from the in-house router) and am getting 55% signal strength. Have it hooked to a solar-panel pack.
Will do this to the 2nd camera, once I purchase another external antenna.
Hope this helps.