Default [Q] Cell standby and battery use

I seem to use battery charge due to 'cell standby' even if mobile data is off. Checking 'restrict background data' under 'data usage' does reduce the drain - but not completely. The drain is about the same as 'Android system' when the device is left on but unused. What is draining the battery - and is it something I can disable or freeze?
Device 1: Sony Xperia Z, Android 4.4.2 rooted
Device 2: Samsung Galaxy Tab 8.4 LTE, Android 4.4.2 rooted