2. Retainability/sustainability. What is the success rate that a consumer does not get interrupted during the consumption of the service, but completes the service by himself/herself? 3. Bandwidth. How fast/slow is the service or response time? These categories will be looked at one by one, putting extra effort into the main focus of this chapter. How can the transmission network be optimised SO that the effect is in that particular aspect of quality? First aspects of GSM/EDGE transmission network optimisation and then UMTS transmission network optimisation will be discussed. 3.14.2 GSM/EDGE Transmission Network Optimisation Performance Monitoring Before performance monitoring begins, it is important to study the actual plans and compare them with what was implemented/commissioned. As in most of the networks the number of sites implemented are in hundreds and thousands and are set up at a very high speed, e.g. a few hundred sites in the air in few months, there is every possibility that an antenna will not be mounted at the exact height or facing the correct direction, power output will not be at the right level, interference problems will develop from the same or external networks, etc. Capacity may also be a problem as the growth of mobile subscribers may be higher than expected. For capacity related problems in the GSM, the optimisation exercise would include studying the existing capacity plans, which means studying the site configurations, topology and transmission media. Once the radio planning engineers come up with new configurations, transmission planning engineers should be able to connect the sites with upgraded configurations. This is a usual problem in green-field networks. Hence, the best cure for such a problem is to make sure that there is a sufficient extra capacity during the planning phase itself SO that new upgrades (after a few months) can take place. Assume that two BTSs each with a 2 + 2 + 2 configuration are connected to a BSC through the 1E1 link. This means that there is no extra capacit