From the empirical study and the workload model obtained, we learn that there are two kinds of factors that a QoS metric must represent. These are (1) resource consumption factors and (2) user satisfaction factors. Resource consumption factors are a measure of the cost incurred due to resource utilization in the system and include CPU, storage and network related parameters. User satisfaction factors quantify the QoS guarantees met and factors that affect the delivery of the desired response quality. Application QoS related parameters such as frame rate, frame width, frame height, color resolution, compression ratio, jitter for video and synchronization skew are good measures to determine the achieved quality and the deviation between the actual response and the desired quality.
We propose a new metric for measuring the effectiveness of video transmission in dynamic situations based on aggregate resource and response factors [20]. We call this metric the weighted resource cost- user-satisfaction ratio and it includes parameters that specify the various objectives of QoS.
To quantify levels of service, we assign
weights to user satisfaction (US) and the cost incurred due to resource
consumption (RC) and construct a benefit function from
the composition of the weighted objectives. Let the QoS metric that represents service to user i be denoted as 
.
where 
represents the weight of the user satisfaction
component and 
represents the weight of the resources consumed
component.
In the following subsections we elaborate further on each factor.
