Marie-José Montpetit

Network coding meets information-centric networking: an architectural case for information dispersion through native network coding

User behavior in the Internet has changed over the recent years towards being driven by exchanging and accessing information. Many advances in networking technologies have utilized this change by focusing on the content of an exchange rather than on the endpoints exchanging the content, in particular to better support mobility. Network coding and information-centric networking are two examples of these trends, each being developed largely independently thus far. This paper brings these areas together at the internetworking layer. We outline opportunities for applying network coding in a novel and performance-enhancing way that could push forward the case for information-centric networking itself.

The future of IPTV

As more and more content migrates to the Internet, “personal” video choices are becoming the norm not the exception. The impact of Internet content and IP-based video distribution is still difficult to evaluate. However, there is obviously no turning back as this content pervades the home and the community. Driven in large part by the near-ubiquitous IP-based communication services, the TV experience has been extended over the years to embrace many of the same ancillary services provided by web applications. This new TV promises to deliver a world of content and services to “any device, anywhere, anytime.” This article addresses the architecture, the value chain and the technical and business challenges of implementing this new connected mobile and social TV experience. To put the architecture into a context, this article also presents a use case of the distributed community Digital Video Recorder (DVR) as an implementation of this vision.

Network Coding as a WiMAX Link Reliability Mechanism

We design and implement a network-coding-enabled reliability architecture for next generation wireless networks. Our network coding (NC) architecture uses a flexible thread-based design, with each encoder-decoder instance applying systematic intra-session random linear network coding as a packet erasure code at the IP layer. Using GENI WiMAX platforms, a series of point-to-point transmission experiments were conducted to compare the performance of the NC architecture to that of the Automatic Repeated reQuest (ARQ) and Hybrid ARQ (HARQ) mechanisms. In our scenarios, the proposed architecture is able to decrease packet loss from around 11-32% to nearly 0%; compared to HARQ and joint HARQ/ARQ mechanisms, the NC architecture offers up to 5.9 times gain in throughput and 5.5 times reduction in end-to-end file transfer delay. By establishing NC as a potential substitute for HARQ/ARQ, our experiments offer important insights into cross-layer designs of next generation wireless networks.

neXtream: A Multi-Device, Social Approach to Video Content Consumption

Video content has become available on an increasingly diverse set of devices and from an ever growing number of sources, creating a vast amount of choice for viewers. At the same time, the varying methods of viewing, interacting with, and sharing content have diverged. This paper introduces neXtream, a new approach to delivering video by integrating multiple devices, content sources, and social networks. This concept is developed following research in social television and converged applications, providing both personalization features and social interaction. NeXtream delivers video by dynamically generating streams of video customized to a viewer, while facilitating a common dialog between users around the content, creating both a userand community-centric viewing experience. NeXtream integrates smartphones, PCs, and TVs to deliver video content to viewers. The paper presents the system concept, theory, and architecture, and describes the developed prototype.

Reducing Operational Costs in Cloud Social TV: An Opportunity for Cloud Cloning

The emergence of social TV has transformed TV experiences, providing a unified media experience across different devices. In response to this trend, we have implemented a multi-screen social TV system, offering video teleportation as an attractive feature. The enabling technology is instantiating a cloud clone to support all media outlets of each user. As the user shifts his attention from one device to the other, the cloud clone might migrate to a better location to reduce its operational cost. This paper investigates this cloud clone migration problem, aiming to minimize the monetary cost on operating video teleportation. Specifically, we formulate it into a Markov Decision Problem, to balance the trade-off between the migration cost and the content transmission cost. Under this framework, four algorithms are proposed to solve this optimization problem. We first characterize an upper and a lower bound for the optimal cost, by considering a random fixed placement and an offline algorithm. We then present a semi-online and a more practical Q-learning approach to make online decisions. Their performances are evaluated based on both simulated and real user traces. The results show that the Q-learning method achieves up to 25% cost compared to random fixed placement in typical scenarios. The savings are affected by the delivery path length, the migration size, and the user behavior pattern. Moreover, our investigations reveal the optimal cloud clone location is either at the nearest or the furthest node to the user along the content delivery path for a single user scenario.

Network Coding for Next Generation Personal Satellite Converged Services

Seeking to meet the resilience, efficiency, and quality of experience challenges of personal and converged satellite services, we present a new approach that leverages the benefits of network coding. The salient features of this strategy are (i) source nodes manage and control the transmission of linear combinations of data packets through heterogeneous communication routes, and (ii) intermediate nodes at each route can generate new coded packets with opportunistic storage. Hence, the amount of data and redundancy sent through each route can meet the required performance of the different sessions. In particular it can help surmount varying channel conditions and correct erasures but also adapt to the different delays and bandwidth that are features of the converged PSAT networks of the future. The main technical challenge is to choose adequate, coding-aware policies to leverage heterogeneous networks based on content and user requirements. We present preliminary analysis that illustrates that exploiting the routes jointly can be performed seamlessly using network coding even with limited feedback capabilities.

Social Television: Enabling Technologies and Architectures

In this paper, we review recent networking developments that will help create the next-generation social television experiences. These include revisiting the way networks are created and using social connectivity to drive physical connectivity and network virtualization. Multipath dissemination and reduction of interruptions will provide better quality of experience. Content protection and privacy are also essential to enable social commentary and metadata applications and will be briefly introduced. Examples of potential applications and results of field trials are also included.

Network Coding Mythbusting: Why It Is Not About Butterflies Anymore

Network coding has been shown to have radical implications for improving current network and storage systems. Because of its disruptive nature, both in terms of techniques and implications, it had naturally led to debate and confusion. This article seeks to dispel some of the misconceptions still associated with network coding, which we term its enduring myths.

An implementation of network coding with association policies in heterogeneous networks

This paper presents a wireless network performance study of a modified TCP/IP protocol stack with a network coding layer inserted between the transport and the network layer. The simulation was performed with the OPNET simulation tool and considered a heterogeneous wireless environment where a mobile device could connect to both LTE (Long Term Evolution) and WLAN (wireless LAN) networks. We simulate various user-network association policies in such an environment with the goal of usage cost optimization under a Quality of Service (QoS) constraint. The results show that using a threshold-based online policy the network usage cost can be reduced significantly while remaining within the users QoS requirements.

Network Coding as a WiMAX Link Reliability Mechanism: An Experimental Demonstration

Our demonstration showcases a network-coding (NC)– enabled reliability architecture for next generation wireless networks. Our NC architecture uses a flexible thread-based design, applying systematic intra-session random linear network coding as a packet erasure code at the IP layer. Using GENI WiMAX platforms, a series of point-to-point transmission experiments are conducted to compare NC with Automatic Repeated reQuest (ARQ) and Hybrid ARQ (HARQ). At the application layer, Iperf and UFTP are used to measure throughput, packet loss and file transfer delay. In our selected scenarios, NC offers up to 5.9 times gain in throughput and 5.5 times reduction in file transfer delay, compared to HARQ and joint HARQ/ARQ. Our demonstration hence illustrates that lower-layer redundancy mechanisms such as HARQ and ARQ incur high cost since they operate at the packet-level. Conversely, running NC at higher layers (e.g., IP) amortizes the cost of redundancy over several packets, thus leading to higher efficiency.