Resource Allocation and Design Issues in Wireless Systems.

摘要

Present wireless communication systems are required to support a variety of high-speed data communication services for its users, such as video streaming and cloud-based services. As the users' demands for such services grow, more efficient wireless systems need to be designed that can support high-speed data and, at the same time, serve the users in a fair manner. One method to achieve this is by using efficient resource allocation schemes at the transmitters of wireless communication systems. Here, the term "resources" refers to the fundamental physical and network-layer quantities that limit the amount of data that can be transmitted over a communication link, such as available bandwidth and power. With the above fact in mind, we study, in this dissertation, physical and network-layer resource allocation problems in three different communication systems, and propose various optimal and sub-optimal solutions. First, we consider point-to-point links and propose greedy low and high-complexity rate-assignment schemes using degraded feedback (ACK/NAK) to maximize goodput of the system. Here, goodput is defined as the amount of data that a transmitter can send to the receiver without any error. Second, we propose optimal and sub-optimal schemes for simultaneous user-scheduling, power-allocation, and rate-selection in an Orthogonal Frequency Division Multiple Access (OFDMA) downlink, with the goal of maximizing expected sum-utility under a sum-power constraint and the availability of imperfect channel-state information at the transmitter. Finally, we consider allocation of network resources in the downlink of large multi-cellular OFDMA-networks and answer, from the view-point of a service provider, complex questions related to network design such as: How many base-stations need to be installed, or how much bandwidth should be purchased given a particular revenue-target, or what pricing scheme must be employed to meet the Quality-of-Service constraints of users and, at the same time, maximize revenue for the service provider? Using our analysis, we also propose a near-optimal resource allocation scheme for multi-cellular OFDMA systems under a truncated path-loss model and different fading models (Rayleigh, Nakagami-m, Weibull, and LogNormal) that is optimal in the scaling sense.