SHO

Misunderstanding:

There are multiple RLs in both uplink and downlink during SHO.

In downlink, there are two/three RLs(radio links) during SHO. Please notice, radio link is just a logic concept which isn’t existed but just describes the connection between Node B and UE. But unlike downlink, there is only one RL in uplink. The reason is, in the downlink, scrambling code is used to distinguish the cells, whereas it’s used to identify UE in the uplink.

Therefore, Node B should send two/three copies of the same data via two/three different cells with different scrambling codes (2 way/3 way softer handover). At the same time, there is only one copy of data transmitting from UE to Node B. But all cells in active set will recieve it respectively and finally soft-combine it in RAKE.

The same mechanism is also applicable for E-DPDCH/E-DPCCH, as well as associated ul DPCCH and HS-DPCCH. As a result, all uplink channels have got diversity receiving gain.