What is the difference between 3G to LTE redirection and 3G to LTE handover.

Question

I know its possible to handover to 3G from 4G in connected state.

But do networks implemented the backwards, I mean 3G to 4G while UE in connected state?? Reselection happens for me but not Handover ?? When UE goes to Cell_PCH or IDLE state it moves back to 4G, not when I am streaming or downloading.

Answer 1

• Redirection means transition from connected state on the originating RAT to idle state on the target RAT.
• Handover means transition from connected state on the originating RAT to connected state on the target RAT.

So, in case of handover the connection is maintained "seamlessly" when switching between 3G and LTE , whereas in redirection the UE is moved to idle state on the target radio, after which the UE has to perform a connection establishment to get things moving again.

Answer 2

Redirection :Its a connected mode procedure and this decision is entirely left to the NW. So what happens the NW will send RRC Connection Release Information with some RedirectCarrier Information like : TargetRATType , Frequency/EARFCN/UARFCN/ARFCN. And Based on that information UE can be redirect to the same RAT or Different RAT.

Handover: It is also a connected mode procedure and initiated by Network. Network will ask UE to send the Measurement reports of the serving cell or the Target Cell and based on that NW will initiate Handover.

Answer 3

In technical terms, redirection is used when UE breaks rrc connection with the current node and latch on to another frequency or technology. While term "handover" is used when network prepares target eNodeB/NodeB and asks UE to latch on to prepared cell.