g and optimisation in 3G networks, let us look at a few concepts that will help in an understanding of the planning process. 7.1.2 System Requirements 3G networks serve a different purpose to earlier networks, and major changes from previous network types are: Fundamentals of Cellular Network Planning & Optimisation A.R. Mishra. © 2004 John Wiley & Sons, Ltd. ISBN: 0-470-86267-X 3G RADIO NETWORK PLANNING AND OPTIMISATION Iu-cs Ju-ps Iu-cs Internet Iu-ps Figure 7.1 Scope of radio network planning in a 3G system (WCDMA) maximum user bit rates up to 384 kbps efficient handover between different operators and technologies (e.g. GSM and UMTS) an ability to deliver requested bandwidth an ability to deliver different services (both CS and PS) with the required quality. 7.1.3 WCDMA Radio Fundamentals Let us try to understand some principle that would be of use in designing a network capable of giving the desired performance. WCDMA (wide-band code-division multiple access) tech- nology has emerged as the preferred and most adopted technology for the third-generation air interface. Air interface technology has changed, SO there are some major differences between the WCDMA and GSM air interfaces: The WCDMA system supports higher bit rates, SO a large bandwidth of 5 MHz is used as compared to 200 kHz in GSM. Packet data scheduling in WCDMA is load-based, while in GSM/GPRS it is time-slot based. Theoretically, only one frequency channel is used in WCDMA, while GSM uses many frequency channels. The limited bandwidth of 5 MHz is sufficient for radio network design. Multipath diversity is possible with rake receivers, while in GSM techniques like frequency hopping are used for (frequency) diversity. Quality control in WCDMA is done using RRM algorithms, while in GSM it was done by implementing various techniques such as frequency planning. Users/cells/channels are separated by codes instead of time or frequency. BASICS OF RADIO NETWORK PLANNING 7.1.4 Service Classes in UMTS In a 3G network, mobile equipment will be able to estab