The Quality of Service (QoS) refers to the capability of a network to offer a service with a certain quality. The quality of a service can be related to a number of different parameters. Much used parameters are:
Which parameter is of importance depends on the service. For example, voice and video services require low latency but tolerate some error rate. By contrast, generic data applications can not tolerate error, but latency is not critical.
The ITU has defined four different categories of services. Each with it's own quality of service associated to it:
This classification is used for instance by 3GPP in the development of UMTS.