First, using integer programming, we achieve the joint relay selection and subcarrier allocation based on maximizing system sum rate in a centralized way.
In such a system, in order to maximize system transmission rates, multiple D2D pairs may use the spectrum occupied by regular cellular users.
With the objective of maximizing secondary system rate by joint time, power, and bandwidth allocation with the primary secrecy rate constraint, the following joint optimization problem is formulated.
It is because that the algorithm in [8] aims at maximizing the system rate, regardless of power consumption of a certain user.
For maximizing the system rate, there are three key issues related to the system optimization problem, i.e., 1) how to mitigate the serious in-cluster interference, 2) how to determine which D2D pairs and CUEs are clustered together, and 3) how to allocate appropriate resources to the clusters.
For each design, iterative algorithms based on convex optimization technique are proposed to maximize the system rate.
In summary, we give the user selection algorithm in Algorithm 2. Since α k affects the data rate greatly, we need to carefully choose a suitable power allocation ratio to maximize the system rate.
The work proposes a framework to adaptively allocate power, subcarriers, and data rate to maximize system spectral efficiency under QoS constraints.
A multi-objective mixed integer programming model was presented by Das et al. (2006) that minimizes variable cost of machine and penalty cost of non-utilizing machine as well as inter-cell material handling cost, and maximizes system reliability with minimizing failure rate.
