A new approach for efficient utilization of resources in WIMAX cellar networks

iskorištavanja resursa u interoperabilnosti širom svijeta za mikrovalni pristup (WiMAX) 802.16e. Ovaj pristup ne samo da učinkovito poboljšava iskorištavanje resursa u baznoj stanici (BS), već i povećava brzinu prijenosa podataka i broj posluženih korisnika. Ovaj rad razmatra silaznu vezu pod-okvira WiMAX BS uporabom djelomične uporabe potkanalnog načina i pristupa ortogonalnog multipleksiranja. Pet je slučajeva bilo uključeno, kao slučajevi u razmjeni, u identifikaciji najboljeg načina iskorištavanja resursa BS u FFR tehnici. Provedena je teorijska analiza u svrhu predstavljanja nove formule za stopu FFR podataka. Rezultati simulacije (slučajevi 5 i 4) otkrivaju da takav pristup ima prednost u odnosu na tradicionalnu tehniku FFR u raznim metrikama. Broj posluženih korisnika i upotrijebljenih slotova povećan je za 100 % u razmatranju slučaja 5. Nasuprot tome, brzina prijenosa podataka (8,69 Mbit/s), učinkovitost subnositelj (2,02 bit/subnositelj/burst), i iskoristivost spektra (0,869 bit/s/H) poboljšani su kod slučaja 4. Zbog učinkovite uporabe širine pojasa i resursa predloženi je pristup uvjerljiv kandidat za postavljanje ćelijske mreže.This paper proposes new static resource utilization (SRU) approach by using the fractional frequency reuse (FFR) technique to enhance resource exploitation in Worldwide Interoperability for Microwave Access (WiMAX) 802.16e. This approach not only efficiently enhances resource exploitation in the base station (BS) but also increases the data rate and number of served users. This work considers the downlink sub-frame of WiMAX BS by using the partial usage of sub-channel mode and the orthogonal frequency division multiplexing access. Five cases were included as a trade-off study to identify the best way of utilizing BS resources in the FFR technique. Theoretical analysis was conducted to present a new formula for the FFR data rate. Simulation results (cases 5 and 4) reveal that the proposed approach has an advantage over the traditional FFR technique in various metrics. The number of served users and slots utilized was increased by 100 % when case 5 was considered. By contrast, the data rate (8,69 Mbit/s), subcarrier efficiency (2,02 bit/subcarrier/burst), and spectral efficiency (0,869 bit/s/H) were enhanced when case 4 was considered. The efficient utilization of bandwidth and resources has made the proposed approach a compelling candidate for cellular network deployment

Performance evaluation of future wireless networks: node cooperation and aerial networks

Perhaps future historians will only refer to this era as the \emph{information age}, and will recognize it as a paramount milestone in mankind progress. One of the main pillars of this age is the ability to transmit and communicate information effectively and reliably, where wireless radio technology became one of the most vital enablers for such communication. A growth in radio communication demand is notably accelerating in a never-resting pace, pausing a great challenge not only on service providers but also on researches and innovators to explore out-of-the-box technologies. These challenges are mainly related to providing faster data communication over seamless, reliable and cost efficient wireless network, given the limited availability of physical radio resources, and taking into consideration the environmental impact caused by the increasing energy consumption. Traditional wireless communication is usually deployed in a cellular manner, where fixed base stations coordinate radio resources and play the role of an intermediate data handler. The concept of cellular networks and hotspots is widely adopted as the current stable scheme of wireless communication. However in many situations this fixed infrastructure could be impaired with severe damages caused by natural disasters, or could suffer congestions and traffic blockage. In addition to the fact that in the current networks any mobile-to-mobile data sessions should pass through the serving base station that might cause unnecessary energy consumption. In order to enhance the performance and reliability of future wireless networks and to reduce its environmental footprint, we explore two complementary concepts: the first is node cooperation and the second is aerial networks. With the ability of wireless nodes to cooperate lays two main possible opportunities; one is the ability of the direct delivery of information between the communicating nodes without relaying traffic through the serving base station, thus reducing energy consumption and alleviating traffic congestion. A second opportunity would be that one of the nodes helps a farther one by relaying its traffic towards the base station, thus extending network coverage and reliability. Both schemes can introduce significant energy saving and can enhance the overall availability of wireless networks in case of natural disasters. In addition to node cooperation, a complementary technology to explore is the \emph{aerial networks} where base stations are airborne on aerial platforms such as airships, UAVs or blimps. Aerial networks can provide a rapidly deployable coverage for remote areas or regions afflicted by natural disasters or even to patch surge traffic demand in public events. Where node cooperation can be implemented to complement both regular terrestrial coverage and to complement aerial networks. In this research, we explore these two complementary technologies, from both an experimental approach and from an analytic approach. From the experimental perspective we shed the light on the radio channel properties that is hosting terrestrial node cooperation and air-to-ground communication, namely we utilize both simulation results and practical measurements to formulate radio propagation models for device-to-device communication and for air-to-ground links. Furthermore we investigate radio spectrum availability for node cooperation in different urban environment, by conductive extensive mobile measurement survey. Within the experimental approach, we also investigate a novel concept of temporary cognitive femtocell network as an applied solution for public safety communication networks during the aftermath of a natural disaster. While from the analytical perspective, we utilize mathematical tools from stochastic geometry to formulate novel analytical methodologies, explaining some of the most important theoretical boundaries of the achievable enhancements in network performance promised by node cooperation. We start by determining the estimated coverage and rate received by mobile users from convectional cellular networks and from aerial platforms. After that we optimize this coverage and rate ensuring that relay nodes and users can fully exploit their coverage efficiently. We continue by analytically quantifying the cellular network performance during massive infrastructure failure, where some nodes play the role of low-power relays forming multi-hop communication links to assist farther nodes outside the reach of the healthy network coverage. In addition, we lay a mathematical framework for estimating the energy saving of a mediating relay assisting a pair of wireless devices, where we derive closed-form expressions for describing the geometrical zone where relaying is energy efficient. Furthermore, we introduce a novel analytic approach in analyzing the energy consumption of aerial-backhauled wireless nodes on ground fields through the assistance of an aerial base station, the novel mathematical framework is based on Mat\'{e}rn hard-core point process. Then we shed the light on the points interacting of these point processes quantifying their main properties. Throughout this thesis we relay on verifying the analytic results and formulas against computer simulations using Monte-Carlo analysis. We also present practical numerical examples to reflect the usefulness of the presented methodologies and results in real life scenarios. Most of the work presented in this dissertation was published in-part or as a whole in highly ranked peer-reviewed journals, conference proceedings, book chapters, or otherwise currently undergoing a review process. These publications are highlighted and identified in the course of this thesis. Finally, we wish the reader to enjoy exploring the journey of this thesis, and hope it will add more understanding to the promising new technologies of aerial networks and node cooperation