Cognitive radio networks (CRN) and Heterogeneous Networks (HetNets) have been proposed to alleviate the problem of data crunch caused by the rapid penetration of laptops, smartphones and tablets in the technology market, as well as the applications that they provide, which are mainly bandwidth-hungry. The common principle to the two paradigms is their intermittent nature. While in CRN the secondary users can access the spectrum with their full potential only when no licensed users (PU) are active, in HetNets a mobile user can access a certain wireless access technology only intermittently.
In both cases, the performance of a mobile user is subject of randomness of the availability of the specific interface (of the idle channel or access technology), and also on other parameters, such as: the traffic intensity, the distributions of the periods with certain access, etc. In order to get a better idea of the nature of interaction between different network and traffic parameters, and the extent of their impact on the performance, we propose different models that enable performance analysis of the CRNs and HetNets key figure of merits, such as the delay, throughput, etc. Finally, based on our results, we solve various optimization problems, whose solutions can lead to enhancing the performance.