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 , 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 . 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 qmax is the maximum of QoE when user obtains the highest processing rate rmax, and parameter qmin is the minimum of QoE when user obtains the lowest processing rate rmin.
As QoE function is continuous, rmin can be obtained by
Similarly, rmax can be obtained by
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.