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INVITED
PAPER
Social Television: Enabling
Technologies and Architectures
The concept of TV and other content being everywhere has been accepted in the
entertainment world and this paper reviews the recent developments that will
create social television experiences beyond the current generation.
By Marie-José Montpetit, Senior Member IEEE , and Muriel Médard, Fellow IEEE
ABSTRACT | 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.
KEYWORDS | Network coding (NC); network on demand; social
networking; social television
I. INTRODUCTION
Let us look into the future:
After a long day of work, Lisa decides to take a
break and watch that TV show that she and her
daughter really like. With her daughter in college on
the U.S. west coast, Lisa will see the show three
hours ahead but wants to make the show as much a
common experience as it was last year. To do so she
leaves comments and recent related pictures for her
daughter to see using her companion application on
her smartphone. About halfway through the show
she gets a message from her husband to share in his
live experience of the Chinese New Year celebrations captured by his smartphone camera. She sends
the video to her tablet application so that the main
Manuscript received February 14, 2012; accepted February 21, 2012. Date of publication
April 6, 2012; date of current version May 10, 2012.
The authors are with the Research Laboratory of Electronics, Massachusetts Institute of
Technology, Cambridge, MA 02139 USA (e-mail: [email protected]; [email protected]).
Digital Object Identifier: 10.1109/JPROC.2012.2189804
0018-9219/$31.00 Ó 2012 IEEE
screen continues to display her show but during the
commercials she switches the screens. At the end of
the show she records the rest of her husband’s video
on her cloud application for future viewing. Later,
her daughter Suzie wants to watch her show but she
is in a crowded bus with four of her college friends
so they decide to watch it on their own devices;
three of them are already subscribing to the TV service with enhanced web experience and the fourth
one is allowed to watch after a commercial. At times
in the show Suzie sees the messages and pictures her
mother left her but her friends can only wonder why
she is smiling so much.
The future is however very near. The concepts of BTV
everywhere[ and Bcontent everywhere[ have readily been
accepted in the entertainment and publishing world with
devices like smartphones and tablets now being the extensions of the living room and library. The Bsecond
screen[ experience is now standard and the use of Facebook or Twitter for content recommendation is common.
And the idea of exploiting metadata for social interactivity
has also been explored [1]. As seen in Fig. 1, the social filter
creates personalized and group-centric viewing experiences that are replacing the traditional approach to television content consumption.
But the use case also emphasizes the requirements of
socially connected TV: international or time shifted, cloud
based, heterogeneous in devices and networks, private and
respecting of content protection.
In this paper, we review recent developments that will
create social television experiences beyond the current generation. We need to revisit the way information is disseminated and how networks are created. We include
examples of network coding (NC) as one of the enabler of
new network paradigms. As proven by many recent studies
and implementations, NC demonstrated improved network
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Montpetit and Médard: Social Television: Enabling Technologies and Architectures
Fig. 1. Using social networking in the TV experience;
adapted from [2].
performance for content distribution and protection and for
optimizing transmission control protocol (TCP)-based services, the basis for the next-generation of social television.
In Section II, we will present architectures using social
connectivity to drive physical connectivity and we define
how network virtualization beyond the current Bsoftware
defined networks[ (SDNs) [3] could be used to create that
connectivity Bon-demand.[ Improved dissemination and
reduction of interruptions to provide better quality of experience as well as examples of potential applications and
results of field trials are the focus of Section III. Content
protection and privacy are also essential to enable social
commentary and metadata applications; they are presented
in Section IV.
II. SOCIAL CONNECT IVITY T O DRIVE
PHYSICAL CONNECTIVITY
Many social media applications require that the members
of the communal experience be connected via some Internet technology using the same network technology or
even the same devices. But inherently, social connectivity
should not imply physical connectivity, but instead should
allow changing the physical connectivity to offer the best
quality of experience.
In addition, models that until a few years ago seemed to
describe the behavior of Internet traffic have become
obsolete. Indeed, the Internet is less and less about flows
moving from a source to a destination but more and more
about information disseminated across a large number of
nodes. The information superhighway has evolved into a
complex organism of information diffusion. In this context, a re-architecture of the way we consider IP packets
becomes necessary and a more diffusive model needs to be
defined; one that takes advantage of multipath and combination opportunities.
Our need to connect socially should drive our physical
connectivity, then if we all want to watch together we
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Proceedings of the IEEE | Vol. 100, May 13th, 2012
should be able to download Bthe right network[ to enable
it on demand and embody the latest strategies. It would
further allow combining and supporting innovation in the
academic and application world at the same time.
Our answer is to define a Bnetwork as a service[ approach leveraging current cloud computing and Bsoftware
as a service[ approaches and enabling radical new technologies based on NC to be deployed efficiently. In fact,
futurologist Daniel Burrus had identified Bcloud computing,[ Bon-demand services,[ and Bvirtualization[ as numbers two, three, and four of the 20 technology trends for
2012 [4]. Combining these and pushing these ideas further, a communal viewing group could define its own
television network and enable viewing on any screen (as
illustrated in Fig. 2).
One use case could be for a video device to require a
more efficient delivery mechanism in a wireless network,
another for a content provider or consumer to request more
protection when transmitted over a nonsecure network. A
social viewing application would learn of available network
services (via service discovery, provisioning, or other) and
the policies for requesting (including user authentication
and location). It is assumed this capability could eventually
become part of the network operating systems but retain its
external call functionality. Network performance enhancements like NC could be available to services and application to improve quality of experience especially to better
manage content distribution in a web space more and more
dedicated to Bwhat[ and less to Bwhere.[
While we are obviously far from this being implemented in a product, the experience of Bwidgets[ and browser
plug-ins to allow the specific applications to be deployed or
adding features to existing services as well as cloud computing services like those offered by the Amazon Elastic
Fig. 2. neXtream concept from [5].
Montpetit and Médard: Social Television: Enabling Technologies and Architectures
Computing service points to networking solutions based
on service requirements.
II I. NETWORK CODING S TRATEGIES
FOR SOCIAL T ELEVISION DELIVERY
The traditional television delivery system, based on content
being acquired and distributed to a single end device under
the control of a single operator is now obsolete. The original content can be combined with ancillary content and
extra features that could be inserted anywhere in the network and rendered on an ecosystem of devices over wired
and wireless networks alike. Because of the scarcity of resources for video, there are increasing demands for content
to be shared locally and to reduce the volume of content
management, retransmission of lost segments, and other
nonrevenue generating traffic. And NC has proven to be an
effective solution for these requirements.
NC considers data traffic as algebraic information [6].
The output of a network coder is a linear combination of a
number of input packets multiplied by coefficients of a
Galois field. It has been shown in an information theoretic
manner to reduce the required number of transmissions to
complete a file or stream operation over noisy or unreliable
networks. Considering that all participants of social TV
will not experience the same network conditions, this provides a strategy for success. Finally, since network codes
are composable, hence the information is capable of being
recombined in the network, they are ideal to communicate
socially enhanced video streams without the need to decode before the destination, hence reduce the effects of
accumulated delays on the quality of the experience.
NC does add complexity to both source and destination
nodes but these are quite simple linear operations and NC
has been successfully implemented in mobile devices such
as phones and MP3 players. The use of random linear network coding (RLNC), where the coding coefficients are
chosen randomly over a chosen small Galois field, creates
the simplest encoder [7]. The application of NC to real-
world problems is recent but it has already demonstrated
its usefulness. One major recent success is the use of NC
to improve the performance of web traffic in wireless
networks.
The analysis of NC with the prevalent protocol of the
Internet TCP was in terms of loss rate, round trip, and
window sizes [8], [9]. The main aspect of the work is to
ensure that losses due to poor channel quality are not
interpreted as congestion by TCP. The main element of the
protocols is to insert a Bshim[ layer between IP and TCP
where datagrams are coded with RLNC and the coded
coefficients are added to the header along with the number of packets combined. In addition, in TCP–NC, the
acknowledgment (ACK) mechanisms are modified to
acknowledge degrees of freedom instead of individual
datagrams. It introduced the concept of Bseen[ packets,
in which the number of degrees of freedom received is
translated to the number of consecutive packets received.
Note that NC only prevents random erasures, not congestion. With correlated losses, TCP–NC follows TCP
congestion mechanisms and the transmission window is
closed. In order to validate these results, trials were conducted around the Boston area with the TCP–NC encoder
implemented in Amazon EC3 and the decoder on a laptop
computer. The results are shown in Table 1. As can be
seen, in very congested areas (Starbucks and downtown)
the gains are significant and allow watching video without
interruptions and loss of synchronization with social
commentary.
The success of the TCP–NC opens the way for other
theoretical work to move into the application realm. The
two most promising are network combining and caching to
improve the network and open new architectures to support the creation of the networks presented in Section II.
In particular by combining less than 5% of network coded
packets from a fourth-generation (4G) network to the
packets of a stressed WiFi network the full quality of a 4G
session can be achieved and at a much lower cost for both
users and operators [10].
Table 1 TCP/NC Trials in the Boston Area
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Montpetit and Médard: Social Television: Enabling Technologies and Architectures
IV. SOCIAL CONTENT DISSEMINATION,
PROTECTION, AND PRIVACY
The scenario presented in the Introduction included the
communal viewing of content on individual devices. This
was to highlight the problems with the current architecture for such experiences: each device is considered individually with unicast traffic wasting bottleneck resources.
Furthermore, device authentication creates nonrevenue
generating traffic. Hence, in a social-video-rich wireless
environment, getting the information to its destination is
not sufficient for commercial success: efficient content
dissemination and content ownership need to be protected, hence, the need for novel approaches to content
protection in a social viewing perspective. Peer-to-peer
mechanisms need to be recognized as a legitimate mechanism for content dissemination [11] while still allowing
both protection of commercial content and privacy of
social commentary.
Digital rights management (DRM) is more about
business cases than content protection per se and is usually
for a single device and a single user. Heavily encrypted
approaches fail to meet the needs of commercially produced content that needs protection when this content is
shared among devices and Bfriends[ and gets annotated
and enhanced. The commercial content and the annotation may need protection but most likely not the same.
One aspect of NC that is yet to be fully exploited is
how its algebraic structure inherently protects the encoded content. We propose an approach for distributed
content verification without the need to contact a centralized trusted authority. Our techniques build upon our
earlier work on constructing encrypted network coded
messages [12] in which only the NC coefficients are encoded which in essence protects the whole encoded
packet: without knowledge of the coefficients the information cannot be intercepted. The decoding time is very
short and significantly faster than traditional decryption
and leads to efficient peer-to-peer implementation. And
REFERENCES
[1] J.-Y. Hwang, P. Pia i Contesa, H. Holtzman,
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while peers can help to disseminate NC video content
they will not be able to decode it without the right key
information (these can be obtained via traditional mechanisms or provisioning). This approach has been implemented successfully on smartphones. But to ensure that
the content itself is the original one, we are adding a
homomorphic signature scheme that will allow validating
the received content even before decoding hence ensuring that the content ownership will be preserved. This
work is ongoing.
V. CONCLUSION
This paper presented a vision for the use of novel technologies for social television viewing. We believe that to
provide the radically new services, combining social connectivity to video streaming and personal content demands redefining the way we currently interact with our
network. Social TV, which combines wired and wireless
networking, necessitates a comprehensive end-to-end and
top-to-bottom strategy. In this view, NC targets the providing
of resiliency and efficiency the operators charge for and the
flexibility and social connectivity demanded by application
developers and consumers alike. The solution to providing
social television is not only to use higher capacity networks
or better compression mechanisms but also to use the existing networks optimally. The results presented in this paper
will apply directly to rising community-based video distribution networks linking ecosystems of smartphones, home
gateways, and caches as well as set-top boxes and digital
video recorders (DVRs) to efficiently use existing resources
and provide the infrastructure for the social connectivity of
the future. h
Acknowledgment
The authors would like to thank S. Ng of NBC
Universal for the invitation to this special issue.
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Montpetit and Médard: Social Television: Enabling Technologies and Architectures
ABOUT THE AUTHORS
Marie-José Montpetit (Senior Member, IEEE)
received the Ph.D. degree in electrical engineering
and computer science from Ecole Polytechnique
of Montreal, Montreal, QC, Canada, in 1991.
She is a Research Scientist in the Research
Laboratory of Electronics, Massachusetts Institute
of Technology (MIT), Cambridge, focusing on
network coding for video transmission. Her research interests include converged video applications, social and multiscreen media dissemination,
and wireless networks.
Dr. Montpetit was a recipient of the MIT Technology Review TR10 in
2010.
Muriel Médard (Fellow, IEEE) received the B.S.
degrees in electrical engineering and computer
science and in mathematics in 1989, the B.S.
degree in humanities in 1990, the M.S. degree in
electrical engineering in 1991, and the Sc.D.
degree in electrical engineering in 1995, all from
the Massachusetts Institute of Technology (MIT),
Cambridge.
She is a Professor in the Electrical Engineering
and Computer Science, MIT. Her research interests
are in the areas of network coding and reliable communications,
particularly for optical and wireless networks.
Prof. Médard was named a 2007 Gilbreth Lecturer by the National
Academy of Engineering. She is a member of the Board of Governors of
the IEEE Information Theory Society.
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