design criteria may be worded as '-95% location probability with a signal of -75 dBm'. Capacity The capacity of a network means how many subscribers the can network support. This is measured by 'network blocking'. Network blocking is expressed as a percentage. A 2% blocking means that for 2% of the time a user will not be able to get a call through. The network blocking can be measured both by drive tests as well as network statistics. In this case network statistics provide a more correct picture of the network blocking. For a second- generation GSM network, where the call set-ups are made on the SDCCH channel and traffic is carried on the TCH or traffic channels, it is possible for the user to get a signalling channel for call set-up but not a traffic channel. By counting the total number of SDCCH allocations versus traffic channel allocations, network statistics can give an accurate measurement of 'traffic channel blocking'. In many cases the government regulating authority, which allots the licences for wireless networks, specifies the blocking. The signalling or SDCCH blocking can be similarly measured by statistics since the initial signalling is on the RACH (random-access channel). Network capacity can be increased BASIC SYSTEM KPIs by adding transmitters provided there is sufficient frequency available. The current 3G networks are also able to generate similar statistics to show traffic channel blocking as well as blocking on the call set-up. Blocking percentages are normally used for voice calls but can be used for any circuit switched call like WCDMA video calls, which use a 64 kbps carrier. Call Set-up Success Rate Even though coverage and blocking measure the ability of the user to make a call, almost all operators measure Call Set-up Success Rate (CSSR) as a key performance indicator. The CSSR comes closest to the user experience in making a call. In addition to coverage and blocking, the CSSR takes into account the effect of interference, fading, etc., which affect the ability of the user to make a 