. If the top management decision is, however, to go for leasing then the main options are basically dark fibre, xDSL/PDH capacity, SDH/SONET capacity or ATM capacity. Dark fibre and xDSL/PDH capacity mean practically that the fibre ends are delivered to two locations to be interconnected or copper cable is delivered to digital distribution frames (DDFs) in two locations. On the other hand, SDH/SONET capacity as well as ATM capacity normally mean that some terminating equipment is delivered and the operator connects the base stations directly to that. Summary There is no way to guide anyone through the problems step by step, as there is such a variety of possible cases, but hopefully the information here is enough to give the reader a checklist of what are the important aspects in this optimisation task SO that wise decisions can be made. Endnote Source: ITU-R P 530-7. Reproduced with the kind permission of ITU. Core Network Planning and Optimisation James Mungai, Sameer Mathur, Carlos Crespo and Ajay R Mishra PART I CIRCUIT SWITCHED CORE NETWORK PLANNING AND OPTIMISATION 4.1 Network Design Process Due to the highly complex nature of network data design, it is imperative to follow a structured process for design of the circuit switched (CS) core network (CN). The network design process (Figure 4.1) can be done in several phases, as described below: Network assessment. The purpose of network assessment is to show the restrictions and advances of the network and to produce dimensioning guidelines concerning user distribution, traffic profiles and service penetration. These issues are taken into consideration in later planning steps. Network dimensioning. The objective of dimensioning is to produce a model of the network in ac- cordance with the operator's forecast user and service profiles. The correct model should achieve the operator's technical objectives while optimising costs of investment. The results of network dimen- sioning form an important part of the network master plan, showing selected network architec