Distributed Energy Efficiency Optimization for MIMO Cognitive Radio Network

Robust Energy-Efficient MIMO Transmission for Cognitive Vehicular Networks

“…Following some typical work such as [19], [19], [21], [25], [26], we represent the total transmission power consumption of the j-th link in the MIMO CR network as p j = βTr(Q j ) + p j,c where Q j denotes the covariance matrix corresponding to M j , i.e.,…”

“…It should be noted that the information on U i for ∀i ∈ J has to be fed back to the individual j-th receiver Rx j when adopting (6) in an optimization scheme. However, as suggested by many existing literature [24], [26], [28], it is appropriate to pre-partition the total power interference that a primary user can tolerate in per-secondary link portions, which can be helpful to realize a distributed implementation with low-complexity and to guarantee possible quality-of-service requirements, while some other study cases [20], [21], [29] have provided their beamforming solutions where the upper bound of a total aggregate interference is not divided. For example, in [30], the aggregate interference constraint directly is combined with the power constraint via introducing auxiliary variables.…”

“…Hence, the conventional fractional programming algorithm based on Dinkelbach's method in [21], [33] would fail to deal with the model. In addition, it can be seen that (14d) is a nonlinear inequality constraint, which increases the complexity of of this model.…”

“…Up to now, there have been many studies focusing on EE transmission of MIMO systems such as [17]- [21]. The authors in [17] aimed to achieve a high energy efficiency and proposed a EE strategy for V2I and I2I (infrastructure-to-infrastructure) communications based on cooperative relay and cooperative MIMO transmissions.…”

“…In our model, we adopt a specific mathematical formulation of the performance metric on EE, i.e., the ratio of the data rate over the power consumed to perform MIMO transmissions, which is similar to the models proposed in [19]- [21]. In these models, only the conditions on maximum power budget and tolerable interference power were considered, and they are under the assumption of perfect CSI.…”