Sony has released the Android 5.1.1 Lollipop software update for a number of its handsets in the Sony Xperia Z range.
The update is already available for a number of devices in the Z range and now it is the turn of some of the older devices.
The Android 5.1.1 Lollipop update is now available for the Sony Xperia Z with the model numbers C6602 and C6603, the Sony Xperia ZL with the model numbers C6503 and C6506, the Sony Xperia ZR with the model number C5503 and the Sony Xperia Tablet Z, with the model numbers SGP311 and SGP312 (WiFi), plus the LTE version of the tablet with the model number SGP321.
The software update has been released for the devices as an over the air update, you can check to see if the update is available for your dfevice from the settings menu.
Source Xperia Blog