Tim McGraw had a supporting role in Friday Night Lights.
Quality of service -LRB- QoS -RRB- mechanism controls the performance , reliability and usability of a telecommunications service .. Quality of service. Quality of service. Mobile cellular service providers may offer mobile QoS to customers just as the fixed line PSTN services providers and Internet service providers may offer QoS .. PSTN. PSTN. Internet service providers. Internet service providers. QoS mechanisms are always provided for circuit switched services , and are essential for non-elastic services , for example streaming multimedia .. circuit switched. circuit switched. streaming multimedia. streaming multimedia. It is also essential in networks dominated by such services , which is the case in today 's mobile communication networks , but not necessarily tomorrow .. Mobility adds complication to the QoS mechanisms , for several reasons  :. A phone call or other session may be interrupted after a handover , if the new base station is overloaded .. handover. handover. base station. base station. Unpredictable handovers make it impossible to give an absolute QoS guarantee during a session initiation phase .. The pricing structure is often based on per-minute or per-megabyte fee rather than flat rate , and may be different for different content services .. flat rate. flat rate. A crucial part of QoS in mobile communications is grade of service , involving outage probability -LRB- the probability that the mobile station is outside the service coverage area , or affected by co-channel interference , i.e. crosstalk -RRB- blocking probability -LRB- the probability that the required level of QoS can not be offered -RRB- and scheduling starvation .. grade of service. grade of service. outage probability. outage probability. blocking probability. blocking probability. scheduling starvation. scheduling starvation. These performance measures are affected by mechanisms such as mobility management , radio resource management , admission control , fair scheduling , channel-dependent scheduling etc. .. mobility management. mobility management. radio resource management. radio resource management. admission control. admission control. fair scheduling. fair scheduling. channel-dependent scheduling. channel-dependent scheduling