Radio Bearer is established, modified, and released with following RRC messages:
1.Radio Bearer Setup,
2.Radio Bearer Reconfiguration, and
3.Radio Bearer Release.
If a radio bearer is setup or reconfigured, not only the RB parameters, but also the transport channel and physical channel parameters have to be set or modified.
It is possible to modify the transport channel configuration. If this is done, the accessory RB parameters are not affected. But a transport channel modification always has an impact on the physical channel setting. A transport channel reconfiguration is triggered with the RRC message.
4. Transport Channel Reconfiguration
It is also possible to modify the physical channel characteristics of a radio bearer only. One example
is a channelisation code re-allocation. This is done with the RRC message
5. Physical Channel Reconfiguration.
Every RRC request, which is mentioned above, can be conducted successfully or fail.
