One of the fundamental challenges in building Peer-to-Peer (P2P) applications is to locate resources across a dynamic set of nodes without centralised servers. Structured overlay networks solve this challenge by proving a key-based routing (KBR) layer that maps keys to nodes. The performance of KBR is strongly influenced by the dynamic and unpredictable conditions of P2P environments. To cope with such conditions a node must maintain its routing state. Routing state maintenance directly influences both lookup latency and bandwidth consumption. The more vigorously that state information is disseminated between nodes, the greater the accuracy and completeness of the routing state and the lower the lookup latency, but the more bandwidth that is consumed. Existing structured P2P overlays provide a set of configuration parameters that can be used to tune the trade-off between lookup latency and bandwidth consumption. However, the scale and complexity of the configuration space makes the overlays difficult to optimise. Further, it is increasingly difficult to design adaptive overlays that can cope with the ever increasing complexity of P2P environments. This thesis is motivated by the vision that adaptive P2P systems of tomorrow, would not only optimise their own parameters, but also generate and adapt their own design. This thesis studies the effects of using an adaptive technique to automatically adapt state dissemination cost and lookup latency in structured overlays under churn. In contrast to previous adaptive approaches, this work investigates the algorithmic adaptation of the fundamental data dissemination protocol rather than tuning the parameter values of a protocol with fixed design. This work illustrates that such a technique can be used to design parameter-free structured overlays that outperform other structured overlays with fixed design such as Chord in terms of lookup latency, bandwidth consumption and lookup correctness. A large amount of experimentation was performed, more than the space allows to report. This thesis presents a set of key findings. The full set of experiments and data is available online at: http://trombone.cs.st-andrews.ac.uk/thesis/analysis.

Wang, Qian. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (p. 71-74). / Abstract also in Chinese. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- A Review of Pricing in Internet Industry --- p.5 / Chapter 2.1 --- Static Pricing --- p.6 / Chapter 2.1.1 --- Flat-rate Pricing --- p.6 / Chapter 2.1.2 --- Usage-based Pricing --- p.7 / Chapter 2.1.3 --- Paris Metro Pricing --- p.8 / Chapter 2.2 --- Dynamic Pricing --- p.9 / Chapter 2.2.1 --- Smart-market Pricing --- p.9 / Chapter 2.2.2 --- Responsive Pricing --- p.11 / Chapter 2.2.3 --- Edge Pricing --- p.12 / Chapter 2.3 --- Comparisons --- p.14 / Chapter 2.4 --- Concluding Remarks --- p.17 / Chapter 3 --- Uplink Pricing --- p.18 / Chapter 3.1 --- Introduction --- p.18 / Chapter 3.2 --- Model Description --- p.26 / Chapter 3.3 --- Uplink Pricing in a Competitive Market --- p.36 / Chapter 3.4 --- The Cooperative Strategy with Uplink Pricing --- p.40 / Chapter 3.4.1 --- The Cooperative Case --- p.41 / Chapter 3.4.2 --- The Threat Strategy --- p.45 / Chapter 3.5 --- Further Discussion --- p.47 / Chapter 3.5.1 --- Accounting Cost --- p.47 / Chapter 3.5.2 --- Peer-to-Peer Locality --- p.48 / Chapter 3.6 --- Related Works --- p.48 / Chapter 3.7 --- Concluding Remarks --- p.49 / Chapter 4 --- Viability of Paris Metro Pricing --- p.51 / Chapter 4.1 --- The Model --- p.52 / Chapter 4.2 --- Flat-rate Pricing versus Paris Metro Pricing --- p.54 / Chapter 4.2.1 --- One-channel Flat-rate Pricing --- p.55 / Chapter 4.2.2 --- Two-Channel Identical Pricing --- p.56 / Chapter 4.2.3 --- Flat-rate Pricing versus Two-Channel Iden-tical Pricing --- p.57 / Chapter 4.2.4 --- Flat-rate Pricing versus Paris Metro Pricing --- p.59 / Chapter 4.3 --- Case Studies --- p.60 / Chapter 4.4 --- Concluding Remarks --- p.62 / Chapter 5 --- Conclusion --- p.63 / A Equation Derivation --- p.65 / Chapter A. --- l Proof for Lemma 3.3.2 --- p.65 / Bibliography --- p.71

Emerging wireless networks are characterized by increased heterogeneity in wireless access technologies as well as increased peer-to-peer communication among wireless hosts. The heterogeneity among wireless access interfaces mainly exists because of the fact that different wireless technologies deliver different performance trade-offs. Further, more and more infrastructure-less wireless networks such as ad-hoc networks are emerging to address several application scenarios including military and disaster recovery. These infrastructure-less wireless networks are characterized by the peer-to-peer communication model. In this thesis, we propose transport protocols that tackle the challenges that arise due to the above-mentioned properties of state-of-the-art wireless data networks. The main contributions of this work are as follows: 1. We determine the ideal nature and granularity of transport adaptation for efficient operation in heterogeneous wireless data networks by performing comprehensive experimental analysis. We then design and implement a runtime adaptive transport framework, *TP, which accommodates the capabilities of the ideal transport adaptation solution. 2. We prove that conversational transport protocols are not efficient under peer-to-peer wireless data networks. We then design and implement NCTP which is a non-conversational transport protocol.

To support extramural learning, Johnson (2005) has proposed the Learning Computer concept, which aims to provide a learning appliance that can be used for studying university courses at any time, from anywhere, and by anybody who might have only basic software and hardware, dial-up Internet connection, and little computer literacy. Lonely extramural students need extra support for interactions and collaboration in learning, especially in second language learning that requires intensive oral language practice between the students and the tutor. This research project was a trial to extend IMMEDIATE (the prototype of the Learning Computer) to a second language extramural course. To meet the requirements of long distance conversation in such a course, a synchronous/asynchronous bimodal approach was conceptualised based on a review of e-learning, communication, and VoIP technologies. It was proposed that the prototype should automatically adapt to either synchronous mode or asynchronous mode according to different levels of Internet connection speed. An asynchronous conversation mode similar to Push-to-Talk (PTT) was also proposed. A VoIP SDK was investigated and used in the prototype for fast development. IMMEDIATE messaging protocols have been extended in the prototype to control call procedures and the asynchronous conversation mode. An evaluation of the prototype which was conducted to assess its usability, functionality and integrity of the prototype demonstrated that users can conduct telephone-like synchronous conversation efficiently at high connection speed. Although the PTT-like asynchronous mode has a time lag problem, especially when two users are both at low connection speed, it is a still a good way for novices to practise second language oral skills. The evaluation has given strongly support to the feasibility and effectiveness of the bimodal approach for applying IMMEDIATE in second language extramural learning.

To support extramural learning, Johnson (2005) has proposed the Learning Computer concept, which aims to provide a learning appliance that can be used for studying university courses at any time, from anywhere, and by anybody who might have only basic software and hardware, dial-up Internet connection, and little computer literacy. Lonely extramural students need extra support for interactions and collaboration in learning, especially in second language learning that requires intensive oral language practice between the students and the tutor. This research project was a trial to extend IMMEDIATE (the prototype of the Learning Computer) to a second language extramural course. To meet the requirements of long distance conversation in such a course, a synchronous/asynchronous bimodal approach was conceptualised based on a review of e-learning, communication, and VoIP technologies. It was proposed that the prototype should automatically adapt to either synchronous mode or asynchronous mode according to different levels of Internet connection speed. An asynchronous conversation mode similar to Push-to-Talk (PTT) was also proposed. A VoIP SDK was investigated and used in the prototype for fast development. IMMEDIATE messaging protocols have been extended in the prototype to control call procedures and the asynchronous conversation mode. An evaluation of the prototype which was conducted to assess its usability, functionality and integrity of the prototype demonstrated that users can conduct telephone-like synchronous conversation efficiently at high connection speed. Although the PTT-like asynchronous mode has a time lag problem, especially when two users are both at low connection speed, it is a still a good way for novices to practise second language oral skills. The evaluation has given strongly support to the feasibility and effectiveness of the bimodal approach for applying IMMEDIATE in second language extramural learning.

Thesis (Ph. D.)--University of Oregon, 2007. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 134-139). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (M.App.Sc.) - Carleton University, 2005. / Includes bibliographical references (p. 95-103). Also available in electronic format on the Internet.

Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Electrical and Computer Engineering, 2007. / Includes bibliographical references.

Thesis (M.Sc. (Computer Science)) - Rhodes University, 2008

Thesis (Ph.D.)--University of Western Australia, 2008.