Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 76-79). Also available in electronic version. Access restricted to campus users.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2009. / Title from title screen (site viewed March 2, 2010). PDF text: ix, 110 p. : ill. (chiefly col.) ; 3 Mb. UMI publication number: AAT 3386564. Includes bibliographical references. Also available in microfilm and microfiche formats.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (p. 87-96).

Thesis (M.S. in Information Technology Management)--Naval Postgraduate School, March 2003. / Thesis advisor(s): Alex Bordetsky, Nancy Roberts. Includes bibliographical references (p. 65-71). Also available online.

Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 171-179). Also available in electronic version. Access restricted to campus users.

published_or_final_version / Industrial and Manufacturing Systems Engineering / Master / Master of Philosophy

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Computer Science / Doctoral / Doctor of Philosophy

 Surge in WLAN development leads to urgent demand for more efficient bandwidth allocation methods. The bandwidth resource becomes more and more scarce. As a consequence, it demands both revenue maximizing and cost efficient allocation methods. To develop this sort of allocation methods, a dilemma between the target of maximizing service quality (in terms of user revenue) and the target of cost efficient allocation must be resolved. In this thesis, two novel auction-based time-slotted WLAN bandwidth allocation models are established, namely the Combination of Single-slot Second-Price Sealed Auction (CSSA) and the Multi-slot Vickrey Auction versus Homogeneous Objects (MVAH). The two models propose a new approach to the solution of the dilemma: user revenue is formulated by not only its revenue gain or loss related to the access to the bandwidth resource, but also by a series of WLAN transmission factors, including Packet Collision Rate and Minimal Packet Transmission error rate. In the two models, wireless bandwidth is time-slotted and bandwidth users compete for the access to these time slots. Initially, each bandwidth user joins a bidding group which is represented by its bidder. There is only one bandwidth provider in the coverage area of the WLAN. After being assigned virtual credit budget, every bidder bids for arbitrary slot combination in each bidding trial or all slots in one bidding trial, according to the bidding rule of adopted allocation model. Non-cooperative game formulation is thereafter introduced to analyze the revenue of each bidder, revenue of the provider, and revenue of the whole allocation system. Specifically, each bidder’s revenue function is differentiated by its bid; the extreme points of this partial differential equation, i.e., the best bids for the bidder, are computed. The bidding strategy formula for each single bidder is derived from the game formulation under the bidder’s budget limit. Each bidder adjusts its bids to attain the optimal revenue obtained from the bidding strategy formula. The allocation pattern is therefore formed. By means of calculation of the all-bidder revenue to whole system revenue ratio, the system efficiency values for both allocation models are analyzed. Conclusions can be derived from the formula of system efficiency: 1) CSSA benefits about 1 percent higher system efficiency unit than MVAH when only average throughputs of user groups differ. And both models iii- gain optimal system efficiencies when bidder’s average throughput differs 65 times pairwise. 2) The larger the number of users connecting to each bidder, the lower the system efficiency. And CSSA model attains higher system efficiency than MVAH when user numbers of user groups differ more than 3.2 times pairwise. In accordance with the pursuit of maximum system efficiency, new WLANs satisfying both revenue maximizing and cost efficient allocation demands can be established. / published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

Interference creates a fundamental barrier in attempting to improve throughput in wireless networks, especially when multiple concurrent transmissions share the wireless medium. In recent years, significant progress has been made on characterizing the capacity limits of wireless networks under the premise of global and instantaneous channel state information at transmitter (CSIT). In practice, however, the acquisition of such instantaneous and global CSIT as a means toward cooperation is highly challenging due to the distributed nature of transmitters and dynamic wireless propagation environments. In many limited CSIT scenarios, the promising gains from interference management strategies using instantaneous and global CSIT disappear, often providing the same result as cases where there is no CSIT. Is it possible to obtain substantial performance gains with limited CSIT in wireless networks, given previous evidence that there is marginal or no gain over the case with no CSIT? To shed light on the answer to this question, in this dissertation, I present several achievable sum of degrees of freedom (sum-DoF) characterizations of wireless networks. The sum-DoF is a coarse sum-capacity approximation of the networks, deemphasizing noise effects. These characterizations rely on a set of proposed and existing interference management strategies that exploit limited CSIT. I begin with the classical multi-user multiple-input-single-output (MISO) broadcast channel with delayed CSIT and show how CSI feedback delays change sum-capacity scaling law by proposing an innovative interference alignment technique called space-time interference alignment. Next, I consider interference networks with distributed and delayed CSIT and show how to optimally use distributed and moderately-delayed CSIT to yield the same sum-DoF as instantaneous and global CSIT using the idea of distributed space-time interference alignment. I also consider a two-hop layered multiple-input-multiple-output (MIMO) interference channel, where I show that two cascaded interfering links can be decomposed into two independent parallel relay channels without using CSIT at source nodes through the proposed interference-free relaying technique. Then I go beyond one-way and layered to multi-way and fully-connected wireless networks where I characterize the achievable sum-DoF of networks where no CSIT is available at source nodes using the proposed space-time physical-layer network coding. Lastly, I characterize analytical expressions for the sum spectral efficiency in a large-scale single-input-multiple- output (SIMO) interference network where the spatial locations of nodes are modeled by means of stochastic geometry. I derive analytical expressions for the ergodic sum spectral efficiency and the scaling laws as functions of relevant system parameters depending on different channel knowledge assumptions at receivers. / text