Thesis Type: Doctorate
Institution Of The Thesis: Gazi University, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği, Turkey
Approval Date: 2021
Thesis Language: Turkish
Student: Metin ÇİÇEK
Supervisor: Nursel Akçam
Abstract:
Cognitive Radio (CR) seeks to identify channels that are empty or infrequent by detecting
the spectrum environment so that the available spectrum can be used more efficiently, and
to allocate appropriate channels to secondary users. In this thesis, simulation studies on
detection and evaluation of communication resource for cognitive secondary users in
Automatic Repeat Request (ARQ) systems have been carried out. The frequencies of the
primary systems can be used by the secondary systems in two different ways: underlay and
overlay. While there is an option to create a certain level of interference on primary users
according to the underlay method, in the overlay model, it is aimed to use the detected
empty channels without allowing any interference on the primary users. In this thesis, CR
applications for Basic ARQ and Hybrid ARQ (HARQ) systems with both methods are
examined. By listening to the ARQ control signals of the primary system, the CR indirectly
has the opportunity to obtain information about the state of the channel and its interference
on the primary system. Thus, the secondary user can determine the action strategy for the
purpose of accessing the spectrum. In the simulations performed for the secondary use of
primary ARQ and HARQ systems, it has been observed that a significant amount of
resources can be provided to the secondary user while maintaining the primary user
throughput performance