New network paradigms for future multihop cellular systems

The high increase in traffic and data rate for future generations of mobile communication systems, with simultaneous requirement for reduced power consumption, makes Multihop Cellular Networks (MCNs) an attractive technology. To exploit the potentials of MCNs a number of new network paradigms are proposed in this thesis. First, a new algorithm for efficient relaying topology control is presented to jointly optimize the relaying topology, routing and scheduling resulting in a two dimensional or space time routing protocol. The algorithm is aware of intercell interference (ICI), and requires coordinated action between the cells to jointly choose the relaying topology and scheduling to minimize the system performance degradation due to ICI. This framework is extended to include the optimization of power control. Both conventional and cooperative relaying schemes are considered. In addition, a novel sequential genetic algorithm (SGA) is proposed as a heuristic approximation to reconfigure the optimum relaying topology as the network traffic changes. Network coding is used to combine the uplink and downlink transmissions, and incorporate it into the optimum bidirectional relaying with ICI awareness. Seeking for a more tractable network model to effectively use context awareness and relying on the latest results on network information theory, we apply a hexagonal tessellation for inner partition of the cell into smaller subcells of radius r. By using only one single topology control parameter (r), we jointly optimize routing, scheduling and power control to obtain the optimum trade-off between throughput, delay and power consumption in multicast MCNs. This model enables high resolution optimization and motivates the further study of network protocols for MCNs. A new concept for route discovery protocols is developed and the trade-off between cooperative diversity and spatial reuse is analyzed by using this model. Finally, a new architecture for MCN is considered where multihop transmissions are performed by a Delay Tolerant Network, and new solutions to enhance the performance of multicast applications for multimedia content delivery are presented. Numerical results have shown that the algorithms suggested in this thesis provide significant improvement with respect to the existing results, and are expected to have significant impact in the analysis and design of future cellular networks.