carry the video traffic (e.g. as Internet traffic), and finally the customer's equipment (e.g. PC, smartphone) will be used for watching the video content. However, two or more elements in this chain may be offered by the same party. For example, the network operator can also be a service provider (e.g. for IP-based TV), and also it can provide the setup box at the customer's premises. Another example is when the con- tent is created by the service provider (a typical example at the present time is Netflix, a service provider offering in-house content). The four-market model is shown in Figure 1.8. However, different multimedia services have different QoS requirements, and the four-market model provides the possibility to identify QoS criteria for one or more components in the model. For example, for multi- media streaming (i.e. video streaming with accompanied audio and data), the following criteria can be applied considering the four-market model: Content creation. Suitability and popularity of the content, codec quality, piracy aspects, etc. Service provision. Ease of navigation to requested multimedia content, security, pric- ing, customer care, etc. Service transport. Bandwidth (in bit/s), latency (i.e. one-way end-to-end delay) and round-trip delay, jitter (i.e. delay variation), error rate, traffic congestion, distortion, etc. Customer equipment. Network interface (e.g. supported bitrates in downlink and uplink), ease of selection and playback of the video content, ease of navigation through the content, ergonomic aspects of the user device, etc. Content, service, and/or network providers Content Service Service creation provision transport Customer equipment Customer perception of the quality Customer Figure 1.8 Four-market model. 1 Introduction 1.5 QoE Concepts and Standards QoE covers entire end-to-end system effects, including customers' equipment as well as network and service infrastructure. Additionally, end-user perception of telecom- munication services is influenced by trends, advertising, tariff