QoE is to measure users’ satisfactory when multimedia services are provided. In this chapter, due to the feature of media cloud, we present a QoE model by defining the obtained cloud processing rate of r, where Q(r) = h(r). Moreover, based on [42], we assume that the QoE function has the following properties:

• h(r) is positive;

• h(r) is concave with respect to r;

• h(r) is continuous and twice differentiable for r.

Note that user’s QoE follows the logarithmic law and QoE function can be modeled in the logarithmic form for applications of multimedia task [43]. Therefore, we adopt the QoE model as the logarithmic function, which is defined as

where a and в are two constant parameters. Both of them are positive and can be different for various types of applications. Parameter q_{max} is the maximum of QoE when user obtains the highest processing rate r_{max}, and parameter q_{min} is the minimum of QoE when user obtains the lowest processing rate rmin.

As QoE function is continuous, r_{min} can be obtained by

Similarly, r_{max} can be obtained by

Design Goals

Our design goals have two desirable objectives as follows: on one hand, user can obtain sufficient cloud resource from media cloud to achieve a satisfied QoE. On the other hand, media cloud can achieve the maximum profit with an optimal price of cloud price.