Non-contiguous spectrum access and small cell network design

The explosive demand for high data rate wireless services cannot be sustained through improvements in PHY layer technologies alone. Opportunistic use of additional bandwidth through dynamic spectrum access and densification of wireless networks are necessary to meet this increasing demand, and this dissertation covers both these aspects. The first part of the thesis focuses on a cooperative spectrum access scenario where nodes exchange non-contiguous spectrum chunks as incentives for cooperative forwarding. An autonomous network is considered where each node gets an initial amount of bandwidth, and uses this bandwidth as a flexible incentive for two hop relaying. This dissertation proposes an incentivized forwarding based resource allocation algorithm which maximizes the global utility of the network while preserving the initial utility of each cooperative node. The second part of the thesis studies power optimal non-contiguous spectrum access. Non-Contiguous Orthogonal Frequency Division Multiple Access (NC-OFDMA), a popular technique in software defined radio research, accesses non-contiguous spectrum chunks by nulling intermediate spectrum. However, nulling subcarriers increases the sampling rate (spectrum span) which, in turn, increases the power consumption of radio front ends. This dissertation characterizes this trade-off from a cross-layer perspective, specifically by showing how the slope of ADC/DAC's power consumption versus sampling rate curve influences scheduling decisions in a multi-hop network. The final part of the thesis focuses on two aspects of small cell network design: (i) a prototype wireless channel measurement system that allows network operators to measure path loss and multipath fading characteristics between multiple candidate small cell locations and their potential users; and (ii) joint cost optimal aggregator node placement, power allocation, channel scheduling and routing for wireless backhaul network of small cells.Ph.D.Includes bibliographical referencesby Muhammad Nazmul Isla