After trying for hours to SSH into Edison wirelessly, I finally discovered that I had to do the following:
ifconfig usb0 down
ifconfig wlan0 down
ifconfig wlan0 up
Apparently usb0 on 192,168.x.15 and wlan0 on 192.168.x.y can't be up together. Unfortunately, I have yet to discover how to make this permanent, so I end up going through this exercise after every reboot.
Jim