Wireless communication system has been experiencing a dramatic increase in data traffic volume due the introduction of new services and applications in every up-to-dated mobile generation technologies. In wireless communication systems, the emerging services and user cases are envisaging to transform digital industry. The quality of service, as well as reliable content delivery are expected from the connectivity between devices. However, more radio spectrum and higher energy consumption are crucial metrics in this wireless communication evolution to react on the exponential growth of data demand related to a huge number of wireless devices data hungry. In this context, this thesis is proposing the approaches to effectively overcome the aforementioned wireless communication challenges. Specifically, the contribution provided by this thesis covers three approaches—particularly combined in two aspects: (1) Solving the clashing between the enormous data demand and the limited radio spectrum. (2) Higher energy consumption in wireless communication system.
The contribution in the first aspect assures the spectral efficiency improvement to overcome the spectrum scarcity from the proliferation of data demand facing in wireless communication. Herein, we consider the cognitive radio network (CRN) system with two scenarios—conventional and dynamic environment. In conventional CRN, we employ fullduplex (FD) communication mode for targeting the enhancement of spectral efficiency in a typical network system. However, since the FD introduces the inherent self-interference (SI) at the SU receiver due the power in SU¡¯s transmit antenna, to ensure the enhancement of spectrum utilization, we propose the effective SI cancellation that allows successful operation of the FD mode in CRNs.
In other words, the approach is based on controlling SU transmitted power to prevent the power throughput trade-off which is facing in the recent literature. The performance corroborates these findings not only for simultaneously sensing the status and transmitting the data, but also enhancing the utilization of the existing limited spectral resources, as was demonstrated by the evaluation of the throughput and sensing efficiency. In dynamically varying environment scenario, we assume the uncertain behavior of the primary network, which makes white spaces to be unstable. This gives motivation proposes both Kriging Interpolation and Kalman Filter(KF) techniques for tracking and estimating the PUs position, then evaluates their performances with respect to the received signal strength indicator (RSSI) scheme.
To optimize the energy efficiency in a typically wireless network, this thesis proposes a technique based on the new network topology (centrals radio access network (C-RAN)) aiming to reduce power consumption in the entire network. Unlike other existing approaches in literature are related to conventional heterogeneous cellular network (CHCN), the new network topology was design to replace CHCN . The new network topology consists of the distributed access points (APs) in network coverage area to improve the energy efficiency with respect to minimum power consumption. Through simulation, the results demonstrate that, the proposed network topology significantly improves energy efficiency (about 60%) compared to CHCN, hence dealing the data traffic in communication network system; and becoming the environment friendly.
Furthermore, the performance evaluation of these three contributing parts was manifested in simulating results where proposed approaches prove their effectiveness over the existing schemes in terms of efficient utilization of existing radio spectrum, as well as the optimal energy efficient, hence leveraging high system throughput and maximum achievable rate capacity. It was finally concluded that, this significant enhancement of spectral efficiency and energy efficiency metrics confirms how all those approaches proposed in this thesis undoubtedly solve the spectrum scarcity issues and energy consumption in wireless communication system.