Radio Network Controller

Other interfaces include Iub (between the RNC and the Node B) and Iur (between RNCs in the same network).

Physically, these interfaces can be carried over SDH over optical fiber, E1 (sometimes referred to as PDH) - over a copper wire or microwave radio.

The actual implementation depends on the network topology; examples are chain, distant star, mesh and loop configurations.

Iub, Iu and Iur protocols all carry both user data and signalling (that is, control plane).

In a relationship to a UE (in a soft handover situation) an RNC can play two different roles.