Cooperative Communication And Improved Resource Allocation In 60-GHz Networks

Recently,60-GHz network is getting more attention because of the expo-nential increase in data demands. The severe propagation and penetration losses of 60-GHz networks are the main limiting factors to achieve its promised data rates in multiple gigabits per second. Signal blockage is also another nuisance that restricts the achievement of higher system capacity. The main challenge is to satisfy the users’expectations and data demands in 60-GHz’s dynamic en-vironment with aforementioned service obstacles. To satiate the huge demands of the bandwidth-craving applications in 60-GHz networks, cooperative com-munication using relays and improved resource allocation are utilized in this dissertation. To enhance the system capacity of 60-GHz networks, this disser-tation proposes a concurrent scheduling algorithm, a centralized distance based relay selection and a novel receiver based distributed relay selection algorithms. The main contributions of the dissertation are as follows:(1). In high-speed data-centric networks, it is argued that the system capacity primarily depends upon the resource allocation schemes. For the problem of the efficient resource allocation in 60-GHz network, the dissertation proposes a concurrent transmission scheduling algorithm based on the concept of ver- tex coloring scheme. The proposed algorithm employs time and space division to allow the transmitter-receiver pair to span over more colors, enabling better time-slot utilization. The proposed algorithm significantly improves the system capacity by 19%; whereas improves the average number of flows per time-slot by 12% as compared to its competing algorithms.(2). The propagation loss in 60-GHz networks may result in up to 28 dB more loss as compared to networks operating at 2.4-GHz. It is also well established that the probability of signal blockage increases with the length of transmission path. Furthermore, transmission on the longer communication paths induces more interference in the network and reduces the number of concurrent trans-missions. To cater these limiting factors, a distance based relay selection algo-rithm is proposed. The proposed algorithm utilizes transmission distance and traffic load on devices to select a relay and proactively reduce the probability of signal blockage. In doing so, the co-channel interference is also reduced, which is compensated in terms of higher capacity. The proposed scheme improves the system capacity by 21% and 46% as compared to multi-hop concurrent trans-mission algorithm and random relay selection scheme, respectively.(3). Signal blockage is also another limiting factor, which is attributed to the very small wavelengths of 60-GHz networks. Signal blockage may result in a loss of up to 40 dB, in addition to propagation loss. A receiver based distributed relay selection algorithm is proposed, which fully leverages the directive nature of 60-GHz networks. The proposed algorithm effectively limits the efforts re-quired for relay selection by reducing the search space. Instead of searching for the whole network space, the relay search is initiated only in neighboring sec-tors in the direction of blockage. The proposed algorithm improves the ergodic capacity by 26% and outage probability by 40% as compared to fixed relay se-lection algorithm.Altogether, this dissertation contributes in the enhancement of system capacity of 60-GHz networks. This is achieved via dual fronts, i.e., cooperative commu-nication and efficient resource allocation. Unlike other works, both centralized and distributed relay selection algorithms are proposed, tailored for different scenarios. The proposed algorithms are proved to be efficient by simulations. We hope the simulation results can provide a theoretical guidance for future dynamic networks.