Jon Crowcroft

Bio: Jon Crowcroft is an academic researcher from University of Cambridge. The author has contributed to research in topics: The Internet & Multicast. The author has an hindex of 87, co-authored 672 publications receiving 38848 citations. Previous affiliations of Jon Crowcroft include Memorial University of Newfoundland & Information Technology University.

Why lossy internetworking and lossless ABR ATM services do not go together-RN/94/21

Abstract: This paper is about the conflicts between two Multiservice Network architectures and to some extent, the Data Transfer Perspective for Congestion Control, in the context of an Internet with some (or most) paths provided by underlying ATM. In the limit, we believe that networks will have excess capacity, and that this will be the model for all traffic control - hence traffic control is about finding the operating point for a fair share of the network. The conflicts between the emerging multiservice model for the Internet, which could operate in this future, and that for ATM, which address a bandwidth limited scenario, arise because we foresee a period during which ATM available bitrate will be used as part of Internetwork paths, the rest of whose hops will either be best effort, or some new sub-service of integrated services internet, but that each is being designed with a view to being the all pervasive model, and not running recursively above the other.

Task Farming in Crowd Computing

Abstract: This chapter contains sections titled: Introduction Ideal Parallelism Model Task Farming Socially Aware Task Farming Related Work Conclusions and Future Work References

On the performance of proactive mobile IPv6 for context-aware all-IP wireless access networks

Abstract: A major challenge in building ‘all-IP’ wireless access networks, besides the use of IP as the unifying layer, relates to the transparency of the IP handoff process as the mobile node (MN) transits across heterogeneous wireless network domains in IPv6 mobility management. Transparency in IP handoffs, however, must be effected in two separate contexts: IP-addressing and (re-)connection latency. Excessive delays during an IP handoff degrades the seamlessness of IP transmission between the MN and its peers. Motivated by experimental results over heterogeneous wireless networks, we discuss why dynamic establishment of IP context-state can help address these limitations that seem inherent in heterogeneous environments. To this end, we provide an in-depth evaluation of Proactive Mobile IPv6 by means of simulations. Our study contrasts the efficiency of proactive context-state establishment, between candidate points of attachment (PoAs), against reactive MIPv6 standard practices over handoff delay, jitter and associated packet loss. Departing from reactive MIPv6 standards, this study brings new insights towards seamless handoffs by investigating the influential aspects of non-determinism in the mobility pattern of the MN. In addition, it demonstrates quantitatively the performance benefit attained by maximising MN's service utility through PoA selectivity embedded in MN IPv6 handoff decision. Copyright © 2006 John Wiley & Sons, Ltd.

Reheating cold topics (in networking)

Abstract: It has been proposed that research in certain areas is to be avoided when those areas have gone cold. While previous work concentrated on detecting the temperature of a research topic, this work addresses the question of changing the temperature of said topics. We make suggestions for a set of techniques to re-heat a topic that has gone cold. In contrast to other researchers who propose uncertain approaches involving creativity, @lateral thinking and imagination, we concern ourselves with deterministic approaches that are guaranteed to yield results1.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Community detection in graphs

Abstract: The modern science of networks has brought significant advances to our understanding of complex systems. One of the most relevant features of graphs representing real systems is community structure, or clustering, i. e. the organization of vertices in clusters, with many edges joining vertices of the same cluster and comparatively few edges joining vertices of different clusters. Such clusters, or communities, can be considered as fairly independent compartments of a graph, playing a similar role like, e. g., the tissues or the organs in the human body. Detecting communities is of great importance in sociology, biology and computer science, disciplines where systems are often represented as graphs. This problem is very hard and not yet satisfactorily solved, despite the huge effort of a large interdisciplinary community of scientists working on it over the past few years. We will attempt a thorough exposition of the topic, from the definition of the main elements of the problem, to the presentation of most methods developed, with a special focus on techniques designed by statistical physicists, from the discussion of crucial issues like the significance of clustering and how methods should be tested and compared against each other, to the description of applications to real networks.