ol between network and UE Common traffic channel Used to transmit dedicated user information to a group of UEs Dedicated control channel Dedicated channel for (UL/DL) control-related information between the UE and network Dedicated traffic channel Similar to DCCH except that it (UL/DL) is used for user information Paging control channel Used to page information to the 7.3 THE SPREADING PHENOMENON 7.3.1 Introduction The spreading phenomenon is the basis of the WCDMA technique. The word 'spreading' refers to the 'spreading of bandwidth' of the actual information. This means that the in- formation is transmitted at a larger bandwidth than the original bandwidth. Through this process, the modulated signal becomes tolerant towards a narrow-band interfering signal. This solves the problem faced by TDMA and FDMA systems, which limit the simultane- ous number of users. By using the spread spectrum technique, efficient use of the spectrum will allow multiple users to use the same frequency band. Using a very common technique known as direct sequencing, the information can be spread over a frequency spectrum. The most common techniques used for this purpose are: DS-WCDMA_FDD (direct-sequence WCDMA frequency-division duplex) DS-WCDMA_TDD (direct-sequence WCDMA time-division duplex) MC-CDMA (multi-carrier code-division duplex) With DS-WCDMA_FDD, the information is spread over the frequency spectrum, while with DS-WCDMA.TDD the frequency band is located on both sides of the WCDMA_FDD signal. With MC-CDMA, the whole of the frequency band is used with a number of carriers instead of one. Both of the techniques FDD and TDD will be implemented, but in the initial phase of a third-generation system only the FDD mode is used because it is more suitable for outdoor coverage purposes. The frequencies for the DS-WCDMA_FDD are: THE SPREADING PHENOMENON downlink: 2110-2170MHz uplink: 1920-1980 MHz. As seen from these frequencies, the bandwidth is 60 MHz in either direction, while the separation between the uplink and downlink is 190 MHz