ific in the downlink. A terminal receiving trans- streams spread with different OVSF codes, even if the missions from one cell will therefore be interfered by data rate, and therefore the spreading factors, are dif- transmissions in neighboring cells as the scrambling se- ferent. This holds as long as the different OVSF codes quences are non-orthogonal. This interference will be are selected from different branches of the channeliza- suppressed by the terminal receiver with a factor pro- tion code tree and transmitted with the same timing. By portional to the processing gain (the processing gain is selecting different spreading factors, physical channels given by the spreading factor divided by the code rate with different data rates can be provided. after rate matching). In the downlink, data to a certain user, including the In the uplink, data are carried on a BPSK-modulated necessary control information, are carried on one QPSK- Dedicated Physical Data Channel (DPDCH). Similar to modulated Dedicated Physical Channel (DPCH) corre- the downlink, different data rates are realized by using sponding to one OVSF code. By varying the spreading different spreading factors for the DPDCH. Coherent factor, different DPCH symbol rates can be provided. demodulation is used also in the uplink, which requires a The spreading factor is determined by the transport channel estimate. Unlike the downlink, where a common format selected by the MAC layer. There is also a possi- pilot signal is used, uplink transmissions originate from bility to use multiple physical channels to a single user for different locations. Therefore, a common pilot cannot be the highest data rates. used and each user must have a separate pilot signal. This Some downlink channelization codes are pre-allocated is carried on the Dedicated Physical Control Channel, for specific purposes. One of the most important is the DPCCH. The DPCCH also carries information about code used for reference signal transmission, in WCDMA the transport format of the data transm