e equipment failure while having an ongoing service, but it is possible, as discussed earlier, to have accessability problems due to the same reason. However, the causes and possible approaches needed to achieve optimisation have already been discussed above. Bandwidth This end user quality aspect is purely defined by transmission capacity, which can be allocated to the user, and the possible transmission channels that can be assigned to a certain service. There might also be some subscription policies related to bandwidth. This quality issue only covers non-real-time services, for obvious reasons. The spectrum of different 3G non-real-time services is SO broad (with many breakthrough services still not even foreseen) and end users SO different that it is hard to tell what is exactly slow and what is a fast enough service. This amounts to psychology. However, simulations are needed to make sure that admission control, offered services, assigned transmission channels, subscriptions and average end user expectations do meet each other. Once again admission control should protect the transmission network SO that no one should have a slow service if services and transmission channels are properly mapped. Transmission Network Optimisation Table 3.16 Physical layer counters Description of counter Severely errored cells Physical layer termination point counters for counting all errored cells with one or more errors in the cell header (containing the header error check error) Table 3.17 IMA counters Description of counter IMA group unavailable IMA group counter for counting one second intervals where the group seconds traffic state machine is down IMA link severely errored IMA link counter for counting one second intervals at the near end seconds containing more than 30 % of the IMA Control Protocol (ICP) cells counted as ICP violation or one or more link defects, loss of IMA frame or link out of delay synchronisation defects except during IMA unavailable second condition IMA link unavailable IMA link counter for countin