Saverio Niccolini

A peek into the future: predicting the evolution of popularity in user generated content

Content popularity prediction finds application in many areas, including media advertising, content caching, movie revenue estimation, traffic management and macro-economic trends forecasting, to name a few. However, predicting this popularity is difficult due to, among others, the effects of external phenomena, the influence of context such as locality and relevance to users,and the difficulty of forecasting information cascades. In this paper we identify patterns of temporal evolution that are generalisable to distinct types of data, and show that we can (1) accurately classify content based on the evolution of its popularity over time and (2) predict the value of the contents future popularity. We verify the generality of our method by testing it on YouTube, Digg and Vimeo data sets and find our results to outperform the K-Means baseline when classifying the behaviour of content and the linear regression baseline when predicting its popularity.

Detecting SPIT Calls by Checking Human Communication Patterns

SPam over Internet Telephony (SPIT) is expected to become a very serious issue in the next years. The threat is going to spin out from the well known email spam problem by bot nets being re-programmed to initiate not just spam emails but also Voice over IP (VoIP) calls. Preventing SPIT is a new problem, because many well-established methods for blocking email spam cannot be applied. Currently, several SPIT prevention methods are being proposed but SPIT prevention research is still at a very early stage. In this paper, we propose an innovative way to detect SPIT calls by comparing applying hidden Turing tests that compare them with typical human communication patterns. For passing these tests, significant resource consumptions at the SPIT generating bot nets would be required which contradicts the spammers objective of placing as many SPIT calls as possible, The proposed method has several advantages compared to other methods that also interact with the caller. We validated its feasibility with a prototype implementation that we integrated into our modular VoIP security system called VoIP SEAL.

Temporal locality in today's content caching: why it matters and how to model it

The dimensioning of caching systems represents a difficult task in the design of infrastructures for content distribution in the current Internet. This paper addresses the problem of defining a realistic arrival process for the content requests generated by users, due its critical importance for both analytical and simulative evaluations of the performance of caching systems. First, with the aid of \youtube traces collected inside operational residential networks, we identify the characteristics of real traffic that need to be considered or can be safely neglected in order to accurately predict the performance of a cache. Second, we propose a new parsimonious traffic model, named the Shot Noise Model (SNM), that enables users to natively capture the dynamics of content popularity, whilst still being sufficiently simple to be employed effectively for both analytical and scalable simulative studies of caching systems. Finally, our results show that the SNM presents a much better solution to account for the temporal locality observed in real traffic compared to existing approaches.

SIP-based mobility management in next generation networks

The ITU-T definition of next generation networks includes the ability to make use of multiple broadband transport technologies and to support generalized mobility. Next generation networks must integrate several IP-based access technologies in a seamless way. In this article, we first describe the requirements of a mobility management scheme for multimedia real-time communication services; then, we report a survey of the mobility management schemes proposed in the recent literature to perform vertical handovers between heterogeneous networks. Based on this analysis, we propose an application-layer solution for mobility management that is based on the SIP protocol and satisfies the most important requirements for a proper implementation of vertical handovers. We also implemented our proposed solution, testing it in the field, and proving its overall feasibility and its interoperability with different terminals and SIP servers.

On Spam over Internet Telephony (SPIT) Prevention

Spam over IP telephony (SPIT) is expected to become a serious problem in the near future. One of the main requirements for a SPIT prevention system is to avoid the involvement of the callee in the SPIT detection process, because this implies disturbing the callee each time an unclassified potential SPIT call arrives. Further requirements include adaptability to different deployment scenarios and flexibility to quickly react to new kinds of SPIT that bypass existing prevention systems. This article analyzes the requirements for SPIT prevention, provides a systematic classification of currently known SPIT prevention methods, and introduces a reference model for SPIT prevention systems. As an instance of the reference model, we designed and implemented an advanced SPIT prevention system, composed of methods that avoid unnecessary callee interaction and adaptive in order to be customized for different scenarios.

An Experimental Evaluation of Voice Quality Over the Datagram Congestion Control Protocol

Most Internet telephony applications currently use either TCP or UDP to carry their voice-over-IP (VoIP) traffic. This choice can be problematic, because TCP is not well suited for interactive traffic and UDP is unresponsive to congestion. The IETF has recently standardized the new Datagram Congestion Control Protocol (DCCP). DCCP has been designed to carry media traffic and is congestion-controlled. This paper experimentally evaluates the voice quality that Internet telephony calls achieve over prototype implementations of basic DCCP and several DCCP variants, under different network conditions and with different codecs. It finds that the currently-specified DCCP variants perform less well than expected when compared to UDP and TCP. Based on an analysis of these results, the paper suggests several improvements to DCCP and experimentally validates that a prototype implementation of these modifications can significantly increase voice quality.

Architecture of a network-aware P2P-TV application: the NAPA-WINE approach

Peer to Peer streaming (P2P-TV) applications have recently emerged as cheap and efficient solutions to provide real time streaming services over the Internet. For the sake of simplicity, typical P2P-TV systems are designed and optimized following a pure layered approach, thus ignoring the effect of design choices on the underlying transport network. This simple approach, however, may constitute a threat for the network providers, due to the congestion that P2P-TV traffic can potentially generate. In this article, we present and discuss the architecture of an innovative, network cooperative P2PTV application that is being designed and developed within the STREP Project NAPA WINE1 Our application is explicitly targeted to favor cooperation between the application and the transport network layer.

Design principles of an operator-owned highly distributed content delivery network

Mobile network operators are experiencing a tremendous increase in data traffic due to the growing popularity of bandwidth-intensive video services. This challenge can be faced either by boosting the capacity of the network infrastructure, or by means of offloading traffic from the backhaul and core network and serving contents from distributed cache servers close to the users. Network operators can extend the coverage of traditional CDNs by making usage of caching locations much closer to the users than traditional CDNs. Additionally, network operators can optimize the caching and delivery of contents by exploiting the complete knowledge of their network for designing a cost-effective infrastructure able to achieve both improved user satisfaction and cost savings. This article provides thoroughly justified design principles for a highly distributed operator-owned CDN while focusing on four key aspects: the optimal location of cache servers, mechanisms for request routing, content replica placement, and content outsourcing and retrieval.

Building a cooperative P2P-TV application over a wise network: the approach of the European FP-7 strep NAPA-WINE

Introduction TV services over the Internet can be provided by either exploiting IP multicast functionalities or relying on a pure peer-to-peer (P2P) approach. The first technique will only work on a network infrastructure controlled by a single broadband operator due to limitations of IP multicast facilities. The main goal of the project is the study of a future system suitable for HQTV live streaming over the Internet based on P2P technology, or a P2P-HQTV system. The major focus is on overcoming todays pure layered approach through a cooperative paradigm in which the application and network layers cooperate to optimize the quality of service offered to end users.

ISE03-2: SPam over Internet Telephony (SPIT) Prevention Framework

SPam over Internet telephony (SPIT) is expected to become a threat inhibiting the delivery of voice services over the Internet in the near future both because of its technical and economical characteristics. Experiences with email SPAM and its analogies with SPIT suggest that SPIT will be difficult to detect with a single detection method. Moreover, personalized management of detection strategies will be needed to increase effectiveness and to adapt the methods to special environments. This paper presents a modular framework for SPIT prevention designed to be easily manageable and extensible. Additionally, the framework makes use of a two-stage architecture in order to exploit the knowledge coming both from the signaling and from the media flows while still allowing real-time delivery of the media content to the user. Following the experience gained with our prototype implementation we also present the most important design issues we encountered and suggest solutions to these issues.