Purpose of WCDMA Channelization Code
  • Channelization code is used to distinguish different physical channels of one transmitter
  • For downlink, channelization code ( OVSF code ) is used to separate different physical channels of one cell
  • For uplink, channelization code ( OVSF code ) is used to separate different physical channels of one UE
  • For voice service (AMR), downlink SF is 128, it means there are 128 voice services maximum can be supported in one WCDMA carrier;
  • For Video Phone (64k packet data) service, WCDMA downlink SF is 32, it means there are 32 voice services maximum can be supported in one WCDMA carrier.
Purpose of WCDMA Scrambling Code
  • Scrambling code is used to distinguish different transmitters
  • For WCDMA downlink, scrambling code is used to separate different cells in one carrier
  • For WCDMA uplink, scrambling code is used to separate different UEs in one carrier
In addition to spreading, part of the process in the transmitter is the scrambling operation. This is needed to separate terminals or base stations from each other.