 PDN Charging Gateway Figure 4.41 GPRS core network elements 4.7.5 Network Optimisation Results A network optimisation project report is made in this module according to the network optimisation plan. An executive summary presents recommended changes and decisions to be made for optimisation of the network and future network performance monitoring. The full report provides the results of the project in a more detailed and explanatory format. An updated follow-up procedure is included. It is a good practice at this stage to organise a workshop to discuss the most important findings of the optimisation project and suggestions for a regular KPI measurement reporting procedure. It is also a good forum in which to discuss any future development paths for the operator. PART II PACKET SWITCHED CORE NETWORK PLANNING AND OPTIMISATION 4.8 Introduction to the PS Core Network The packet switched service is a communication system in which data is divided and transmitted in packets of a predefined size. Its special feature is that communication between terminals with differing speeds and formats is possible since transmission/reception is performed after the data has been stored at the exchange. In contrast to circuit switching where a circuit is occupied until all data transfer has been completed, packet switching improves efficiency through the common use of circuits. In a 2.5 generation GSM network, the GPRS was introduced to handle data in a more efficient manner. Due to the above-mentioned benefits of packet switching, a packet switched domain was introduced in the GPRS as CSD and HSCSD (high speed CSD) could not fulfil the requirements of handling bursty data traffic. A GPRS network can be broadly divided into two domains, the RF domain and the packet core domain. The RF domain extends from the handset till the BSC including BTS and associated interfaces. The packet switched domain is beyond the Gb interface towards the Internet, comprising SGSN, GGSN, DNS, border gateway, charging gateway, firewalls, their interfaces an