Future wireless network architecture

With widespread use of wireless networks and the emergence of multiple Radio Access Technologies (RATs), the present-day network architecture is currently being transformed into the one global infrastructure vision, called Beyond 3rd Generation (B3G) [1]. B3G is a heterogeneous Internet Protocol (IP) based wireless access infrastructure, which aims to provide higher capacity and quality of service (QoS) to the users even considering the limited radio spectrum through support of a cooperative diversity [2] and reconfigurability [3]. In a system with a cooperative diversity each node in the network can act both as an information source and a relay. Such information relay may increase the capacity and diversity gain in wireless networks, leading to the improved performance in terms of both area coverage and QoS [4]. In B3G the cooperative communication assumes that the network infrastructure will rely on more than one RAT: depending on encountered specific conditions (e.g., hot-spot requirements, traffic demands, etc.) at different times in different areas the RATs will cooperate with each other to achieve the maximization of QoS levels offered to users. To support the cooperative communications in B3G, the advanced management functionality is required to deal with the reallocation of traffic to different RATs and sub-networks, as well as the mapping of applications to QoS levels [5-8]. The move towards the reconfigurability concept was initiated by the development of the Cognitive Radio Network (CRN) – the network, where the nodes with fixed licensed spectrum (so-called primary nodes) can share their spectrum resources with nodes without fixed licensed spectrum (secondary nodes) [9]. In B3G the reconfigurability aims to provide essential mechanisms for terminals and sub-networks, to enable them to adapt dynamically and transparently to the most appropriate RAT depending on encountered situation (hot-spot requirements, traffic demands, etc.). The reconfigurability allows for the dynamic allocation of resources (such as bandwidth, service rate, etc.) to RATs, and invokes a variety of new possibilities with respect to the more efficient utilization of available spectrum [1, 9-10]. With regard to the diverse challenges arising upon the development and deployment of B3G, this thesis aims to: 1. Explore the potential ways of implementing the future wireless infrastucture based on existing wireless networking standards and coexistance of air such features ; 2. Study the main principles of cooperative and cognitive communication which lie in: (a)cooperation and information exchange between all member subnetworks; (b)support of reconfiguration capabilities of all nodes/user terminals within the network; (c)coexistence of the nodes/user terminals belonging to different RATs comprising the network ; (d)intelligent resource planning involving cognitive reactive and proactive management of the network resources based on external (environmental) aspects, as well as on goals, capabilities, experience and knowledge. 3. Develop the efficient radio resource management platform in order to provide increased spectrum utilization and enhanced end-to-end QoS for users of different RATs with and without fixed spectrum allocation. 4. Investigate the problems of co-existance, intra- and cross-layer control between different RATs comprising the network, including: (e)PHY layer channel modeling, including noise and interference models, log-distance path loss, shadow and multipath induced fading, physical layer transmission techniques (MCS, AMC); (f) MAC/RLC layer design, including traffic generation models, packet scheduling, ARQ/HARQ, DCF/HCF, buffer status reporting, etc.; (g)Cross-layer control: necessary parameters (such as packet arrival rate, buffer occupancy, SINR) are observed on MAC and PHY; control of available resources (such as bandwidth, data rate, buffer capacity) on PHY layer; (h)Application layer QoS for users as a result of undertaken control on PHY/MAC layer.