UL Channelization Code in UMTS

One day I stumbled upon a question  "How NodeB come to know about the channelization of an UL  Data channels that UE transmit? Does it communicated by UE in some message on some channels or what?

Generally the channelization code and SF are fixed for control channels in UL and DL both directions but when it comes to data channels there are certain things which are defined and some are to be derived by Network.

Network(RNC) only communicates the MIN Spreading Factor to be used in UL in physical channel configuration. For example in case of HSUPA RNC communicates the MIN SF to be used in both BearerSetup/Reconfig and RL_Setup/Reconfig which could be 2SF2, 2SF4, 2SF2 + 2SF4.

In UL direction there is no dearth of coding resources as its being selected by UE and it does not have to share this resource. UE always selects higher SF and do the TFCI/ETFCI selection based on its transmit power. So network(NodeB) is not even aware of the SF in use to decode a particular channel and this is necessary to know the SF and Channelization code to decode a channel.

So first of all NodeB derive the Spreading Factor using the received data rate from the UE.

TBD....