Have you ever wondered what happens to your phone signal when you walk or drive? How come I don’t lose the signal like on my home router?
I will now introduce you to a technical term often used and necessary in cellular mobile telecommunications, namely the term handover.
This refers to the process of transferring an ongoing call or data session from a cell (BTS – antenna/equipment pair) to an adjacent cell without loss or interruption of service.
How is it done? The makings of handover is divided into three processes.
- The first process involves identifying the conditions for changing the network and initiating the need for handover. In the case of the picture above, it consists of interpreting the signal level as the vehicle moves from cell 1 to cell 2. When it reaches the shaded area, the need for handover is initiated in order to preserve the signal.
- The second process is to identify new resources to perform the handover connection and additional routing operations. In this case, in the picture it consists in identifying cell 2.
- The third process is the control of the data flow so that the cell can be changed without losing the connection. Basically, it will switch from the cell 1 connection to the cell 2 connection without the user noticing this.
There are other situations in which the handover process can be initiated. Below is a list of some of these situations:
– when the maximum connection capacity of a cell is reached, for new calls, then an attempt is made to route to a free adjacent cell;
– in non-CDMA networks when the channel used by the phone interferes with another phone using the same channel in a different cell, then the call is transferred to a different channel in the same cell or to a different channel in another cell to avoid interference