Content diffusion between wireless mobile devices

Thomas, Bryce (2015) Content diffusion between wireless mobile devices. PhD thesis, James Cook University.

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The architecture of today's Internet was conceived in the 1960s and 1970s. Networking aimed to solve the problem of resource sharing -- enabling remote access to scarce and expensive devices such as card readers, high-speed tape drives and supercomputers. The resulting communication model was one of a conversation between exactly two hosts -- a resource consumer and a resource provider. Over the past 50 years, computers have undergone a metamorphosis from scarce, multimillion-dollar machines occupying large rooms to cheap and ubiquitous pocket-sized devices. The value of the Internet no longer lies in facilitating access to scarce hardware. Rather, the Internet now primarily derives its utility from enabling large-scale electronic content distribution and retrieval.

At odds with the content-centricity of modern network applications is the host- centricity of the prevailing network architecture. The juxtaposition of the two paradigms has been the impetus for new research into alternative Future Internet architectures under the umbrella title of Information-Centric Networking (ICN). Though individual visions for ICN vary substantially in ambition and detail, the central role of content is widely recognized. There is all but consensus that con- tent identity and security ought to be independent of content location, enabling seamless replication throughout the network. This would permit secure content retrieval from a cache geographically and/or topologically close to the end user while balancing load for the content distributor. What separates the current wave of research from the myriad of application-specific distributed caching overlays is a generalization which intends to render content the primary network abstraction. One proposal emblematic of ICN's core principles is Content-Centric Networking (CCN). CCN envisages an Internet architecture in which Internet Protocol (IP) packets are replaced by comparably sized chunks of named content. Attached to each chunk is a cryptographic signature allowing the validity, relevance and provenance of content to be assessed, irrespective of sender. Like other ICN projects, CCN solves a critical problem on the path towards truly distributed con- tent dissemination -- establishing trust in content received from untrusted senders. This opens up compelling new caching strategies in which content may be retrieved from any device in the network, including those not typically thought of as content distributors.

This thesis is motivated by one particular application of CCN's universal secure caching -- content diffusion (spreading) directly between colocated mobile wireless devices. Over the past decade, commercial and private Content Delivery Network (CDN) overlays have proliferated on the Internet as a way of geographically distributing cached copies of content, balancing load for content producers and increasing performance for consumers. These CDNs however are limited in their reach by the granularity of the facilities in which content servers may be installed -- typically Internet Service Providers' (ISPs') Points of Presence (PoP). Building a 'CDN' of sorts from the colocated end user devices themselves is a natural progression of the distributed caching architecture and one which we consider the 'final frontier' for CDNs. The meaning of this statement is that there are no content caching locations closer to an end user than another colocated device.

The potential advantages of direct device-to-device content sharing are manifold: (i) higher throughput, (ii) lower latency, (iii) extended network coverage and (iv) reduced load on infrastructure. Despite being conceptually attractive in these respects, relatively little is known about the intrinsic spreading potential of opportunistic encounter (contact) networks. It is to this matter that we direct our attention in this thesis. Drawing upon empirical spatiotemporal traces of device mobility and inferred device encounters, we conduct a simulation-driven exploration of opportunistic content diffusion. We address a number of aspects of spreading potential, which are divided into three separate papers. In the first, we perform simulations parameterized by site, time and number of source devices in order to establish the impact of these variables on content diffusion. We also motivate content diffusion by integrating real-world application usage statistics from a popular campus maps application into our simulations. Our second paper addresses the impact of margins of trace uncertainty on diffusion potential, as well as the inherent variation in diffusion potential as a function of the randomly chosen source device. Our third paper seeks to understand how nodes' spatiotemporal preferences impact on spreading potential. We achieve this through the presentation of a set of novel null models which separately decorrelate the relationships between times, locations and nodes. We also describe how the null models can be generalized to any contact network in which contact events are predicated on node colocation.

As a preamble to the three papers on content diffusion, we present one additional paper, the subject matter of which is the SPDY web protocol. As such, the set of three papers just described are in fact numbered 2, 3 and 4 in the thesis, with the SPDY paper being listed as paper number 1. The SPDY paper is the by- product of a thorough review of the current state of the art in near-term protocol innovations which we conducted during the early stages of the research. The SPDY paper offers an interesting point of comparison between the pragmatic strategies behind near-term protocol improvements and the broader long-term research perspectives on computer network architecture.

Item ID: 52475
Item Type: Thesis (PhD)
Keywords: computer networks; content diffusion; content sharing; content-centric networking; handheld devices; mobile ad hoc networks (MANET); mobile devices; portable devices; spreading; wireless technology
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This is a thesis by publication. Published articles included as chapters 4 and 5 have been redacted from the thesis due to copyright restrictions. The full thesis may either be requested via document delivery at your local library or viewed in the Eddie Koiki Mabo Library at JCU, Townsville.

Three publications arising from this thesis are available from the Related URLs field. The publications are:

Chapter 4: Thomas, Bryce, Jurdak, Raja, and Atkinson, Ian (2012) SPDYing up the Web. Communications of the ACM, 55 (12). pp. 64-73.

Chapter 5: Thomas, Bryce, Atkinson, Ian, and Jurdak, Raja (2014) Content diffusion in wireless MANETs: the impact of mobility and demand. In: Proceedings of the 10th International Wireless Communications and Mobile Computing Conference, pp. 959-966. From: IWCMC 2014: 10th International Wireless Communications and Mobile Computing Conference, 4-8 August 2014, Nicosia, Cyprus.

Chapter 7: Thomas, Bryce, Jurdak, Raja, Zhao, Kun, and Atkinson, Ian (2016) Diffusion in colocation contact networks: the impact of nodal spatiotemporal dynamics. PLoS ONE, 11 (8). pp. 1-21.

Date Deposited: 08 Feb 2018 06:35
FoR Codes: 08 INFORMATION AND COMPUTING SCIENCES > 0805 Distributed Computing > 080503 Networking and Communications @ 50%
10 TECHNOLOGY > 1005 Communications Technologies > 100510 Wireless Communications @ 50%
SEO Codes: 89 INFORMATION AND COMMUNICATION SERVICES > 8901 Communication Networks and Services > 890103 Mobile Data Networks and Services @ 100%
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