ance. In fact, sometimes the cells are very proximate to each other but for some reason (low traffic, the presence of an obstacle, hardware anomaly, etc.) they perform few interhandover attempts. In this case the relationship should be maintained. In any case, after deletion is downloaded to the network, a control mechanism will assess the impact on quality. Adding new adjacencies is a more complicated concern. It uses surrounding cells measurements that are then ranked from the strongest to the weakest. The number of measured samples of each cell is also to be considered in order to declare only useful new adjacencies. The add/delete mechanisms are launched on a regular basis and hand-in-hand in order to optimise the number of adjacencies. Each cell can support up to 32 neighbours, but to increase handover performance it is recommended not to exceed some 15 adjacencies per cell. Automation in adjacency management can also include a parameter incoherence check. A specific subsection presenting the types of checking that can be useful to do is included in the handover performance section. Parameter Optimisation At the deployment phase, operators tend to use standard parameter templates, as thousands of GSM parameter exist. However, due to differences between cells (propagation and interference environment), it is necessary to fine-tune some parameters on a cell-by-cell or adjacency-by-adjacency basis in order to get optimum performance. The essential idea behind optimisation is how to find the correct value for a specific parameter applied to a specific cell. Even this task, which requires optimisation expertise and is time consuming, can be automated. A complex mechanism based on four main principles allows such automation to be performed: definition of subsystem architecture; choice of adequate control techniques; consideration of control algorithm mapping to network elements; assessment of performance according to initial rules. Radio Network Planning and Optimisation Cellular Troubleshooting Troubleshooting co