Samsung Galaxy S3 has a 4.8″ 720p display. It was the first device to have a quad-core Exynos 4412 processor, with each core clocked at a maximum 1.4 GHz. It packs NFC, wireless charging capability, and the latest wireless radios. It ships with Samsung’s Nature UX interface. At the time of its launch, it ran on Android 4.0.4 ICS.
Google has released the Android 5.1.1 update for few devices and based on it many developers have come up with their Android 5.1.1 ROMs. Samsung Galaxy S3 can be updated to Android 5.1.1 using the BlissPop ROM which is based on the CyanogenMod ROMs. Follow the guide given below.