| Abstract: | 4th
generation (4G) mobile communication networks have resolved many
problems of 3rd generation mobile networks. Following the boom
development of communications, it has a dramatically increase in the
number of user terminals that leads to foresee the limitations of 4G
mobile communication standards. It is expected that beyond 4G mobile
networks or 5G mobile networks will provide not only very high
transmission rate but also utilize radio resource effectively under the
constraints of high user density and limited radio spectrum. So we will
present a vision for beyond 4G mobile networks or 5G mobile cellular
networks based on the notions from expert international forums and
well-known published papers. To solve communications demand of high user
density areas, cognitive radio and femtocell are proposed as core
technologies for future wireless communications and for providing
wireless voice and broadband services to customers in small areas such
as home, office or designated locations, which are deployed and
installed by user terminals without depending on mobile network
operator. In our research, we study a framework for cellular-femtocell
network optimization based on the cognitive interference management
methodology. We first introduce a feasible architecture model of
cognitive cellular-femtocell networks which we consider as a mobile
network model of beyond 4G mobile communications. In this model,
femtocells, what are deployed to extent coverage and reduce the load for
macro cellular networks, are equipped with cognitive radio function
that it allows operating in the same radio spectrum with macro cellular
network. Based on the sensed information from its distinct environment,
femtocell can fully reuse all available spectrums or reuse limited by
predefining. With the interference level sensed from its environment,
femtocell can autonomously allocate a proper channel which has strong
signal strength and minimum interference to macro environment. With our
best knowledge about the cognitive cellular-femtocell networks, we
propose two novel channel allocation schemes which will be compared with
two existing channel allocation schemes, and then design a simulation
program that content all of our research to demonstrating and supporting
the research work. With those schemes, cellular-femtocell networks will
have self-configuration procedures to adapt resource management
effectively. Performance study results obtained by the simulation
program, show that the two proposed channel allocation schemes
outperform other existing schemes in terms of unsuccessful probability
of new connection requests considering user’s QoS constraint. |
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