ty in case it needs to be upgraded and there are considerable lead times for purchasing new equipment and installing them. There can also be considerable lead times and extra installation costs for leasing more bandwidth. The decision about the period under optimisation should come for transmission optimisation from operator top management. Transmission Media Selections The selection of transmission media might not be very relevant to all operators since there are plenty of operators with some installed base of transmission capacity due to an already existing fixed line network or 2G network. However, capacity needs for transmission in 3G are likely to grow SO high that some new selections and modification are likely to be needed, especially for the last mile for base stations. Even if there is not significant installed base of transmission capacity, selecting the transmission media is partly linked to a larger decision of whether to use own or leased transmission. That decision has the same parameters as any other owning versus leasing decision that individuals need to make, such as with a car, apartment, etc. If top management decides to go for own transmission then microwave radio links provide an attractive option. Microwave radio links are normally faster to install, even if most radio links are subject to permission from authorities controlling the radio frequencies, and the failures with microwave radio links are easier to overcome. They do carry a larger risk of failure, however, compared with copper or fibre, due to radio propagation problems in rainy conditions, misalignment, etc., but conveversely, on the credit side of copper and fiber, once they are installed they are very resistant to errors. The main reason for problems with fibre and copper is human error; either someone cuts the cable or by error disconnects it. The downside of having fibre or copper is the long lead times to get it installed, with first the delay to get all the permissions to do the wiring and then to do the actual wiring itself