lan consists of attributing frequencies to all TRXs using the optimum way. For this purpose, the regular design of sectors is crucial. In fact, the idea is to reallocate the same Radio Network Planning and Optimisation frequency to sectors shooting in the same direction and enough far from each other not to interfere. This means in practice to plan area by area rather than site by site (area is a set of 4, 7 or more sites). Performing new frequency plans is a recurrent operation that takes place each time that adding new sites reaches a certain spectral limitation. At the launch phase, operators can handle the number of sites using the width of the frequency band. In this way dedicated channels can be attributed to each TRX. Nevertheless, at a certain stage, frequency hopping becomes necessary to introduce in order to spread interference. Two frequency hopping modes exist: synthesised frequency (SFH) and base band hopping (BBH). Base Band Hopping BBH consists of attributing fixed frequencies to all TRXs, and then the TCH hops from TRX to TRX within the same cell. This kind of hopping mode planning is quite difficult, since it is obligatory to allocate one dedicated frequency per TRX. Moreover, the maximum number of possible channels for a mobile to hop on is the number of hopping TRXs. This brings a certain limitation to the interference diversity. Hardware requirements for BBH are remote tune combiners at the BTS level. Synthesised Frequency Hopping SFH is more suitable for mature networks. It is easier to plan, since hopping TRXs use mobile allocation lists, SO there is no need to plan them. However, it requires regular engineering for azimuths. It consists of planning the BCCH layer and then the hopping parameters (HSN, MAIO, etc.). SFH requires wideband combiners that have a higher insertion loss. A detailed method for planning an SFH based network is now presented. BCCH Strategy The BCCH layer is more sensitive to interference than the TCH as the broadcast channel transmits continuously in time. Therefore th