2. This being a generic and simplified scenario, we have not specified the variables in
designing the DEA input/output variables formulation. The variables will have to
be defined in the specific implementation contexts of presence-enabled services. As
we have seen in the previous sections, there are various types of presence-enabled
services, each of which need a set of inputs, some of which are common and some
which are unique to their specific implementation requirements. And consequently,
the output requirements also vary. For example, location information service performance
requirements will primarily be the real-time accuracy of the data, whereas for
call services, the availability of QoS parameters will be the most important output
variables for monitoring and control. So, depending on the implementation-specific
requirements, the input-output variables can be defined.
Using these assumptions, now we can formulate the algorithm.
In this algorithm, the number of suppliers/providers (called as Decision-Making. Units.
or.DMUs in context of DEA) of presence-enabled services about which adequate SLA
parameter values/historical data is available = n. Number of output decision variables Y =
SLA parameter values + cost = s .
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