3G/UMTS

Measurement Control and Handover

I got a question long time ago, saying "Why we see measurement control/measurement report almost always in Handover procedure ?"

In real live network, it would be common to perform 'Measurement Control' both for SHO and HHO. But purely in terms of technology, 'Measurement Control' and 'Measurement Report' is not a mandatory part for any Handover process. If I explain these two procedure in a very simplified (a little bit over simplified) manner, I would say

i) Handover - Changing a communication cell from one to another, or changing the number of communication cell to one to another.

ii) Measurement Control - Ordering UE to perform a specific measurement (e.g, the signal quality of the current cell or the signal quality of another cell).

Basically these two procedures are independent.

But in reality, most of network operator combine these two process mainly to improve the successbility of the handover.

For example, let's suppose that there are two cells (let's call them Cell A, Cell B respectively) and a UE is now communicating to cell A and now your network is trying to let UE change the communication cell from Cell A to Cell B. The simplest way would be to send UE a handover command, saying "change Cell from A to B". But what if the cell B is not ready to communicate with your UE. For example, the signal quality between Cell A and UE is so bad and it will almost for sure that the call would drop as soon as the UE changes the cell ?

Do you still want to change the cell ?

The answer would be No.

Main for this kind of reason, the network try to make it sure that the target cell (the UE is handed over to) is good enough condition before trying handover. That's why in most live network log, you would see measurement control/measurement report message before the handover.