resources should be less (1-2%). RNC Dimensioning The purpose of RNC dimensioning is to provide the number of RNCs needed to support the estimated traffic. The main limitations that should be taken into account are: maximum number of cells; maximum number of base stations; maximum lub throughput; amount and type of interfaces; input data from the customer or RF planning; RNC dimensioning example; RNC areas. Some Parameters Used in WCDMA Dimensioning Eb/No is the ratio of the average bit energy and noise spectral density. The value of Eb/No is dependent on the type of service, UE speed and radio channel: (2.12) (2.13) IDL =Iown(1-a)oth = PN (2.14) Radio Network Planning and Optimisation where Prx = received power Iown = total power received from the serving cell (excluding own signal) Ioth = total power received from other cells a = orthogonality factor R = bit rate W = bandwidth PN = noise power Thus, the required RF C/I (channel-to-interference) ratio needed to meet the baseband Eb/No criteria, also known as the ratio of energy per chip to total spectral density, can be given as (2.15) In WCDMA systems, the Eb/No is larger than the S/N (signal-to-noise) ratio by an amount of the spread- ing factor. Thus, communication is possible in the WCDMA system even when S/N for a connection at the receiver is typically much smaller than unity. Macro Diversity Gain (MDC) The concept of a soft handover (described later) is used for this. It is calculated using the average overall connections by taking into account the difference of received signal branched and the UE speed. In the UL direction it is about 0 dB and in the downlink direction it is 1 dB. Interference Margin This is calculated from UL/DL loading values (n). UL indicates the loss in link budget calculations due to load while in DL it shows the loss of sensitivity of the BS due to load: NR = -10 log10(1-n) (2.16) Power Control Headroom At the cell edge the UE (usually a slow moving one) does not have enough power to follow the fast fading dips. The margin against 