Abstract:
For about the past decade and a half research efforts into
cognitive radio networks (CRNs) have increased dramatically. This
is because CRN is recognized as a technology that has the potential
to squeeze the most out of the existing spectrum and hence virtually
increase the effective capacity of a wireless communication system.
The resulting increased capacity is still a limited resource and its
optimal allocation is a critical requirement in order to realize its
full benefits. Allocating these additional resources to the secondary
users (SUs) in a CRN is an extremely challenging task and integer
programming based optimization tools have to be employed to
achieve the goals which include, among several aspects, increasing
SUs throughput without interfering with the activities of primary
users (PUs). The theory of the optimization tools that can be used
for resource allocations (RA) in CRN have been well established
in the literature; convex programming is one of them, in fact the
major one. However when it comes to application and implementation,
it is noticed that the practical problems do not fit exactly
into the format of well established tools and researchers have to
apply approximations of different forms to assist in the process.
In this survey paper, the optimization tools that have been applied
to RA in CRNs are reviewed. In some instances the limitations of
techniques used are pointed out and creative tools developed by researchers
to solve the problems are identified. Some ideas of tools
to be considered by researchers are suggested, and direction for future
research in this area in order to improve on the existing tools
are presented.
