operation. Then, if we main- tain operation at this minimum EV/N, we can obtain the optimum performance of the system. From Ref. [23] we can define the relationship between the number of mobile users M, the processing gain Gp, and the Eb/No ratio as follows: M 22 . (2.25) On the other hand, the Eb/No performance can be seen better in relation with Shannon's limit in AWGN5, which simplified can be presented as: (2.26) E2.2108,2=0.69=-1.59 dB (2.27) provides error-free communications. Then for Shannon's limit the number of users can be projected from: (2.28) Shannon's theoretical limit implies that a WCDMA system can support more users per cell than classical narrow-band systems limited by the number of dimensions. On the other hand, this limit in practice has ENo = 6 dB as a typical value. However, due to practical limitations, accommodating as many users in a single cell as indicated by Shannon's limit is not possible in a CDMA system, and this applies also to the UTRA FDD. Thus, cell capacity depends upon many factors, (e.g. receiver-modulation per- 5 Additive White Gaussian Noise. System Analysis Fundamentals formance, power control accuracy, intersystem interference), and the upper-bound theo- retical capacity of an ideal noise-free CDMA channel has also limitations by the proc- essing gain Gp [23]. Multiple transmissions in neighbouring CDMA cells using the same carrier frequency cause interference, denoted by B factor. This event will cause reduction of the number of users in a cell, because the interference from users in other cells has to be added to the interference generated by the other mobiles in the user's cell. may range from 0.4 to 0.55. In addition to the interference factor, we also introduce the imperfect power control or power control accuracy factor a, which ranges from 0.5 to 0.9. Interference can be reduced by the voice activity factor V ranging from 0.45 to 1.0. If we use direc- tional antennas at the base station, the sectorized cell will have a sectors, the antennas used at the cell each w