Nokia (Canada)

Opportunistic routing is a new routing paradigm that takes advantage of the broadcast characteristic of a wireless channel for data delivery in a wireless mesh network. Network coding has recently emerged as a new coding paradigm that can significantly improve the throughput performance of a WMN. In this article we explore the combination of opportunistic routing and network coding for improving the performance of a WMN. We first review existing opportunistic routing and coding-aware routing protocols, respectively, classify these protocols based on different criteria, and discuss their merits and drawbacks. We then propose a coding-aware opportunistic routing mechanism that combines hop-by-hop opportunistic forwarding and localized inter-flow network coding for improving the throughput performance of a WMN. Through opportunistic forwarding, CORE allows the next-hop node with the most coding gain to continue the packet forwarding. Through localized network coding, CORE attempts to maximize the number of packets that can be carried in a single transmission. Simulation results show that CORE can significantly improve the throughput performance of a WMN as compared with existing protocols.

The theory of propagating waves near a surface is reviewed with an eye to gain insight into the mechanisms involved, and to provide analytical-based models, for power-efficient on-body propagation. The Zenneck wave, and in particular the Norton wave, are appraised as candidate mechanisms for the propagation. For flush-mounted (ldquoband aidrdquo) antennas, desired for on-body sensors, the Norton wave is the only direct propagation mechanism between the sensors. The Norton wave fits very well to simulation results presented here, and comparisons are also made with available published physical experiments, although these measurements typically feature the optical paths of elevated, or non-flush, antennas.

Standardization activities are nearly complete for single wavelength 25 Gb/s time-division multiplexed (TDM) passive optical networks (PONs) and well underway for 50 Gb/s TDM PONs. There is considerable debate in the industry about which technology will be the “next step” after 10 Gb/s TDM PON, now finally starting to ramp up to mass deployment. 50 Gb/s PON clearly brings a 2 × bandwidth advantage over 25 Gb/s, at least in the downstream direction. On the other hand, the increase of speed to 50 Gb/s brings with it a substantial receiver sensitivity penalty of at least 4 dB, which has a chain effect on transceiver architecture, cost, and time-to-market. In this paper, each of those elements is investigated, quantified, and compared to 25 Gb/s.

We assess the status of current generation 25G and 50G time division multiplexed passive optical network (TDM PON) technologies based on leveraging the cost efficiencies of the Ethernet intra-datacenter ecosystem. As a first step towards 100G TDM PON, we predict the real-world impact of a flexible modulation enhancement to 50G PON, whereby four-level pulse amplitude modulation (PAM4) symbols can be transmitted at the same symbol rate as 50 Gb/s PAM2, but only where excess margins permit. We find that sufficient margins are likely to exist to allow for a majority of future 50G PON optical network units to operate at 100 Gb/s PAM4. Next, we look at the options for a 100G PON capable of supporting the full loss budget and reach requirements. There is no technical risk if coherent technology is adopted, but intensity-modulation and direct-detection (IM-DD) will provide lower complexity, lower cost, and lower power dissipation. We evaluate this option and conclude that by following IM-DD Ethernet optics to 100 GBd, single wavelength IM-DD will continue to be feasible for 100G PON and will be a strong contender for the next generation of PON after 50 Gb/s.

Abstract Users on social networks such as Twitter interact with each other without much knowledge of the real-identity behind the accounts they interact with. This anonymity has created a perfect environment for bot accounts to influence the network by mimicking real-user behaviour. Although not all bot accounts have malicious intent, identifying bot accounts in general is an important and difficult task. In the literature there are three distinct types of feature sets one could use for building machine learning models for classifying bot accounts. These feature-sets are: user profile metadata, natural language features ( NLP ) extracted from user tweets and finally features extracted from the the underlying social network. Profile metadata and NLP features are typically explored in detail in the bot-detection literature. At the same time less attention has been given to the predictive power of features that can be extracted from the underlying network structure. To fill this gap we explore and compare two classes of embedding algorithms that can be used to take advantage of information that network structure provides. The first class are classical embedding techniques, which focus on learning proximity information. The second class are structural embedding algorithms, which capture the local structure of node neighbourhood. We show that features created using structural embeddings have higher predictive power when it comes to bot detection. This supports the hypothesis that the local social network formed around bot accounts on Twitter contains valuable information that can be used to identify bot accounts.

The goal of this paper is to summarize research in designing and developing an application framework for intelligent and mobile agents.Agents are the next significant software abstraction; they will soon be as ubiquitous as graphical user interfaces are today.The major contribution of the work described here is a reusable design and implementation of an architecture that addresses all levels of agent behavior.The design is robust and well founded, based on object oriented design patterns.The framework has been employed in preliminary applications in network management and enterprise integration.However, agent systems are still evolving; to facilitate future development, the framework is documented with patterns.

Online advertising, also known as web advertising or Internet marketing, is the means and process of promoting products and services on the Internet, and it has been one of the important business models for the Internet. Due to its lucrative nature and its large scale of adoption, it has also been a target for malicious parties with various attack aims such as getting a cut of online advertising revenues, obtaining a user’s privacy, and spreading malware. Over the years, a great deal of research has been conducted on online advertising. Recently, the health of the online advertising ecosystem has become more of a concern for both advertisers and regular Internet users. Advertising budgets have been abused, and Internet users’ privacy and security have been infringed. In this article, we broadly study threats to online advertising and trace the root causes from a systems point of view. Existing threat mitigation strategies are also reviewed and analyzed. To protect online advertising, which has been an essential funding source of many free Internet services, several challenges still need to be addressed, including the need for transparency of the advertising ecosystem and software vulnerabilities on the client-side. To overcome these challenges, we conclude by brainstorming some innovative ideas on some potentially interesting and useful research directions.

Cladding-pumped optical fiber amplifiers are of increased interest in the context of space-division multiplexing but are known to suffer from low power efficiency. In this context, ytterbium (Yb) co-doping can be an attractive solution to improve the performance of erbium (Er) doped fiber amplifiers. We present a detailed direct comparison between Er/Yb-co-doping and Er-doping using numerical simulations validated by experimental results. Two double-cladding fibers, one doped with Er only and the other one co-doped with Er and Yb, are designed, fabricated and characterized. Using the experimentally extracted parameters, we simulate multi-core fiber amplifiers and investigate the interest of Er/Yb-co-doping. We calculate the minimum gain of the amplifiers over a 35-nm spectral window considering various scenarios.

Smart phones pose new challenges to usable security. Current means of specifying security policies or preferences for resource sharing are either woefully inadequate or too hard to use. This article presents a policy model approach toward usable security for smart phones. In particular, the approach adopts a semantic-based policy representation to help users' understanding of security policies and to better reflect what users really want. Furthermore, given the special nature of smart phones' usage, social awareness plays an important role. In this regard, the authors present propose a socially-aware policy reasoning model based on the results of a user study.

We present the design and characterization of a cladding-pumped amplifier with erbium doping located in an annular region near the core. This erbium-doped fiber is proposed to reduce gain saturation, leading to smaller gain compression when compared to uniform core doping. Through numerical simulations, we first compare the performance of three fibers with different erbium doping profiles in the core or the cladding. When the doped fibers are operated at the optimum length, results show that the smaller overlap of the signal mode field with the annular erbium doping region leads to higher gain and lower saturation of the amplifier. A single-core erbium-doped fiber with an annular doping and a D-shaped cladding was fabricated. Measurements demonstrate less than 4 dB of gain compression over the C-band for input power ranging from -40 dBm to 3 dBm. Small gain compression EDFAs are of interest for applications that require input channel reconfiguration. Higher gain and saturation output power are also key issues in cladding-pumped multi-core amplifiers.

Current differential protection typically requires symmetrical communications channels—with equal latency in each direction—for correct operation. Conventionally, this has been delivered using protocols such as IEEE C37.94 over a time-division multiplexing wide-area network (WAN). Modern packet-based WANs offer improvements in efficiency, flexibility, and cost-effectiveness for utility applications. However, jitter is unavoidable in packet-based networks and, in extreme cases, jitter inevitably results in substantial asymmetrical latency in communications paths. This paper clearly defines how a new source of asymmetry arises due to the use of “de-jitter” buffers, which can jeopardize critical protection services. This is demonstrated using an analytical modeling approach, which precisely quantifies the degree of risk, and through real-time demonstration with actual devices, involving current differential protection over an IP/MPLS WAN. Using a novel method of real-time manipulation of Ethernet traffic to emulate large WANs, the modeling approach has been validated. It is shown how the sensitivity of relays to asymmetry depends on the protection settings and the magnitude of the measured load current. To address the risk of protection maloperation, a new approach for compensating for asymmetrical latency has been comprehensively validated. These developments will be of immediate interest to utilities operating, or migrating to, a packet-based infrastructure.

In this work, two balanced dipole antennas in both the cellular band and the PCS band have been measured using a GTEM (Gigahertz transverse electromagnetic mode) cell and the results have been compared with those obtained using an anechoic room. It is pointed out that correct rotation plane of the antenna under test (AUT) inside the GTEM cell is essential to produce right antenna patterns The effectiveness and limitation of antenna measurements using a GTEM cell and associated measurement uncertainties are discussed.

We report on the current state and future direction of ubiquitous VR, based on presentations and discussions during the 2009 International Symposium on Ubiquitous Virtual Reality. In the symposium, enabling technologies and applications for realizing ubiquitous VR on mobile devices are discussed and several approaches were proposed aimed at improving ubiquitous VR applications with pervasive and ubiquitous computing technologies.

Cross-correlation coefficients of two side-by-side /spl lambda//2 dipole antennas as a function of space separations are calculated from antenna patterns measured using a 3D diversity antenna measurement system in an anechoic chamber. Autocorrelation coefficients determined from the measured patterns of a /spl lambda//2 dipole antenna agree well with the theoretical model. The effects of antenna mutual coupling on the cross-correlation coefficients of two /spl lambda//2 dipole antennas are obtained experimentally and analysed.

We report the characterization of a cladding-pumped multicore fiber with annular erbium doping for low gain compression over the C-band (1528.8 nm to 1563.9 nm). The fiber aims to minimize saturation effects by placing the erbium doping in the cladding where the signal intensity is lower. The challenge of ensuring adequate erbium ion solubility in the cladding, without unduly raising its refractive index, was answered by using aluminophosphosilicate for the doped region. Before assembling the eight-core amplifier with fan-in and fan-out, we needed to determine the optimum fiber length to meet the gain compression target when the eight cores are loaded, for a given pump power injected in the cladding. We thus performed a thorough experimental characterization of a single core. This allowed the determination of all the relevant fiber parameters needed to do numerical simulations and predict the multicore fiber amplifier performance under the fully loaded scenario. For the first time, these numerical results are compared to the experimental results of a fully loaded multicore amplifier with cladding pumping and erbium doping in the cladding. We discuss the amplifier performance in terms of gain compression when the input power signal is varied, as would be the case in dynamic optical networks. We also examine the core-to-core gain variations and the sensitivity of the design to fabrication variations. Results show that significant reduction in gain compression of multicore cladding-pump amplifiers can be achieved with the proposed annular doping design in the cladding, although improvement in the fabrication uniformity of the core will be required for practical applications. Lastly, we discuss how this erbium doped fiber design can also lead to improved power conversion efficiency (PCE) in cladding-pumped amplifiers.

This paper reviews the work of industry organizations that are defining the requirements on, and the details of, transport slicing functionality and models, in support of 5G network slicing automation and assurance. Slicing permits the simultaneous support of multiple service frameworks from a converged infrastructure and is key to the 5G operational vision, but poses challenges related to cross-domain coordination, automation and SLA assurance. Transport network slicing is an important component of the overall network slicing picture, and its mechanics are being defined collaboratively by organizations including 3GPP, ETSI ZSM and NFV, and IETF. Supporting demonstrative implementation is being done in the Linux Foundation ONAP project.

We address the challenge of correctly estimating the position of wireless sensor network (WSN) nodes in the presence of malicious adversaries. We consider adversarial situations during the execution of node localization under three classes of colluding adversaries. We describe a decentralized algorithm that aims at determining the position of nodes in the presence of such colluders. Colluders are assumed to either forge or manipulate the information they exchange with the other nodes of the WSN. This algorithm allows location-unknown nodes to successfully detect adversaries within their communication range. Numeric simulation is reported to validate the approach. Results show the validity of the proposal, both in terms of localization and adversary detection.

Notification is a service that addresses devices and users with messages to be processed immediately or at a specific time. Notification is important for delivering emergency, warning, and other timely messages. In this article extensions to include notification service in the data transport system called IP DataCast used in the DVB-H mobile television standard are presented. The architecture of IPDC in DVB-H is first overviewed, and the notification service elements complementing it are described. Next, the notification protocols and message formats are defined, and the system operation is explained. The presented notification system is now part of the new IPDC over DVB-H standard.

A study on the effect of hands on mobile handset antennas has been carried out experimentally with antenna prototypes and an active mobile phone. It is reported that the positive hand effect exists for small antennas in the 900 MHz band. Measurements of antenna prototypes and an active mobile phone show that the positive hand effect can improve antenna total efficiency by 1 to 2 dB in the 900 MHz band.

Inference on location data has generated a great amount of interest and there are two data sources. GPS location data from GPS-based endpoint devices have high precision, but suffer from intermittent availability, small coverage of users and extra demand on devices' battery. Telecom mobility data, on the other hand, have the complementary advantages of continuous availability and complete coverage but generally with coarse location accuracy. The focus of this paper is on the development of a location insight system for activity labeling and user segment inference, based only on Telecom mobility data enriched with point-of-interest (POI) data. Specifically, we estimate activity patterns based on Bayesian techniques while infer user segments via a tree-based classification algorithm. We test the performance of our inference system via simulated mobility data and investigate the impact of important factors such as granularity of data. We conclude that imprecise location data, enriched with other source of information, can be used for the development of new generation activity inference models.