RF - RRC Status                                         Home : www.sharetechnote.com

At high level view, LTE RRC has only two status (RRC Connected and RRC Idle). It may sound too simple comparing to other Radio Access Technology, but the detailed processes undergoing in these two status is not as simple as you might think. Following illustration is based on 36.331 4.2.1 UE states and state transitions including inter RAT.

As an engineer, you need to have ability to see both forest and the individual trees in the forest. This illustration is important but only a picture of forest. To see the individual trees in the forest, you need to look into almost every pages in this site. I recommend you to switch back and forth between this page and other pages related to each individual process.

Connected User (UE) vs Active User (UE)

I was asked of what is the difference between Connected UE and Active UE. However, I don't personally see the term Active User in any of 3GPP specification (Probably I missed something when I am reading the documents). However, from the context in which these two terms are used, I would define these terms as follows.

• Connected User : User (UE) that are in RRC Connected
• Active User : User (UE) that are in RRC Connected and undergoing User Data Transaction and you may include the UE that performing Signaling Messages (e.g, sending Measurement Report etc) as well.

Based on this definition, you may say Active User can be a kind of subset of Connected user meaning that the number of Active User in a specific moment (at a specific subframe) is highly likely to be smaller than the number of Connected User. It seems that the concept of Active User is often used in the context of estimating the capacity of a base station. In terms of base station point of view, UEs not transmitting/receiving any data (ether U plane or C plane data) would not put any load on it. So these UEs can almost be ignored for that specific moment.