Tinitus ...
I don't think it's the RealTek 8192CU chip.
I have had the problem I described with various wireless adaptors ... with Atheros AR9271 and Reattek RT5370 chips.
If you are using an EdiMax with the 8192CU chip and have not taken special measures then it could be going into power saving mode and dropping the connection.
I do the following which I found on the RPi forum ... to stop the Edimax losing connection after periods of non-use/overnight.
(by MrEngman » Sun Nov 24, 2013 5:47 pm)
Make a file 8192cu.conf in directory /etc/modprobe.d/ with the command ...
sudo nano /etc/modprobe.d/8192cu.conf
and add the following lines ...
# Disable power management
options 8192cu rtw_power_mgnt=0 rtw_enusbss=0
I also do the same for 8188eu ... just in case I use that type of wi-fi adaptor
Hope this helps