t fall under the first three categories are included, such as e-mails. This class of service has the least stringent quality of service requirement of all the four classes. 7.1.5 Elements is a WCDMA Radio Network User Equipment (UE) The mobile terminal is called user equipment. The basic principles remain the same as explained in Chapter 2, but with the addition of the capability to handle data calls. User equipment can be divided into three parts, USIM, ME and TE, as shown in Figure 7.2(a). The USIM card (also known as SIM) contains authentication information and associ- ated algorithms, encryptions and subscriber-related information. In contrast, the mobile 3G RADIO NETWORK PLANNING AND OPTIMISATION Figure 7.2(a) Simplified block diagram of user equipment (UE) equipment (ME) is user-independent. The Terminal equipment (TE) is responsible for ter- mination of the entire control and user-plane bearer with the help of the ME. Base Station (BS) The base station is also known as 'node B' in a WCDMA radio network. It is more complex than the base station of a GSM network. Its functions include handover channel management, base-band conversion (TX and RX), channel encoding and decoding, interfacing to other network elements, etc. A simplified version of it is shown in Figure 7.2(b). Mod./ Lub Interface Amplifier Demod. Network Interface Filters Spreading Figure 7.2(b) Simplified block diagram of WCDMA base station Amplifiers and Filters This unit consists of signal amplifiers and antenna filters. The amplifiers are used to amplify the signal coming from the transceiver and going towards the RF antenna (the downlink signal), while the filters select the required frequencies coming in from the RF antenna (the uplink signal) and amplify the signals for further processing before sending them to the receiver part of the TRX. Transceiver The TRX is capable of transmitting and receiving signals, by handling uplink and downlink traffic. It consists of one transmitter and one or more receiver. Modulation/Demodulation and Sprea