Broadband interactive services provided through TV-centric technologies
via bidirectional satellite connection
Gabriele Boccolini1, Hendrik Knoche2, Marco Luise1, Jean-Michel Merour3, Luca Vignaroli4
1
Dept. of Information Engineering, University of Pisa, Italy
{gabriele.boccolini, marco.luise@iet.unipi.it}
2
Dept. of Computer Science, University College London, UK
{h.knoche@cs.ucl.ac.uk}
3
Thales Alenia Space, Toulouse, France
{jean-michel.merour@thalesaleniaspace.com}
4
Rai - Centro Ricerche e Innovazione Tecnologica, Torino, Italy
{l.vignaroli@rai.it}
Abstract
This paper presents a smart collection of existing
technologies to provide low-cost satellite delivery
of triple-play services to the home with a TVcentric terminal. The satellite connections provides
the best and quickest solution to reduce the digital
divide in less-favored areas, which has been
considered as a major issue in the diffusion of
broadband access. The platform employs DVB-S(2)
and DVB-RCS technologies in the forward and the
return link, respectively. The flexible framing
structure of DVB-S2 and the adoption of the
Adaptive Coding & Modulation (ACM)
functionality allow an efficient exploitation of the
satellite resource. The paper provides a description
of the TV-Centric services, the required QoS and
the relevant system architecture.
1. Introduction
A critical element which constitutes an obstacle to
harmonious continent-wide development is the
“social divide”. The lack of skills and ability to use
a computer or other interactive devices create a
significant barrier to broadband access to older
people. TV-Centric technologies to provide
interactive triple-play services satisfy the demands
of the broadest possible span of European consumer
communities.
Accessing and using new media, such as interactive
TV, Internet, mobile video and new combinations
of those, whether via a computer, a mobile phone,
or a TV Set Top Box (STB), will grow
considerably, especially in major metropolises and
most developed areas. Unfortunately, rural areas in
well-developed countries and large areas with
limited terrestrial network infrastructure in
developing countries are still excluded from
traditional access choices.
Satellite-based telecom systems provide the best
and quickest solution to reducing or eliminating the
digital divide in less-favored areas to allow the
diffusion of broadband access, owing to their wide
geographical coverage and the speed and ease of
deployment of terminal equipment. For satellite
systems to fulfil this role, however, they must be
efficient and cost effective, and capable of full
inter-working with state-of-the-art terrestrial
broadband networks.
This paper presents a TV-Centric two-way
broadband satellite architecture developed in the
framework of the UNIC (UNIversal satellite home
Connection) project (Boccolini et al. 2007, Seager
et al. 2007)), sponsored within the 6th EU Research
Programme Framework. The UNIC architecture
provides TV-Centric triple play services to actual
end-users in the home employing DVB-S(2) and
DVB-RCS technologies in the forward and the
return link, respectively, together with a newly lowcost defined architecture for the distribution of
connectivity to end-users.
The flexible framing structure of DVB-S2 and the
adoption of the ACM functionality allow
optimizing the transmission parameters for each
individual user on a frame-by-frame basis,
dependant on path conditions and required QoS,
under closed-loop control via the satellite return
channel. The result is an efficient exploitation of
the satellite resources and even greater gain of
DVB-S2 over DVB-S for point-to point
applications.
The main application scenario of the UNIC system
is a remote village not served by terrestrial
broadband infrastructures (i.e. ADSL, WiMax).
This platform is therefore designed to provide (i)
broadband connectivity to the homes, via a bidirectional Collective Satellite Gateway (CSG)
located in a building or a village city hall (e.g.
serving a group of houses, a village, a large multistorey building), and (ii) conventional TV/HDTV
services via Direct-to-Home (DTH) reception. The
user STB, allowing seamless access to the various
services independently from their origin/transport
infrastructure, is an hybrid DVB and IP box
connected to the CSG through a wired (Ethernet
LAN) or wireless (WiFi/WiMax LAN) local
broadband network (for interactive IP-based
services) and to the DTH receiving antenna through
the home cable network (for TV/HDTV services).
The UNIC system provides a set of primary
services such as Internet, interactive TV, IPTV,
HDTV, VOIP and videoconference services
together with another set of innovative services
such as surveillance, monitoring, tourism
information, distance learning and home-based care
services that will reshape the way consumers use
DTV.
The system two-way platform fully support the IP
and TCP/IP protocols, resulting in an optimisation
of the required satellite bandwidth. A reduction in
the amount of bandwidth needed lowers network
costs and allows for greater profitability of new
services.
The first step of the project was to imagine a
contour of services towards users of existing
satellite TV services who have no access to
alternative services (PC access, web access, email,
video conferencing, music download). Afterwards,
we identified which services were more suitable
and viable when carried over new satellite
technology. The result of this study is a list of
potential services listed in the Section II.
Once the services were defined, the technology
adaptation needed to be prototyped to enable their
delivery. This required a thorough evaluation of the
key parameters impacting the quality of each
service - bandwidth, packet loss, delay and jitter alongside a study of the likely usage across a
population to estimate the burstiness of the
underlying video traffic. In section IV we will
describe the overall architecture of the system.
2. TV-Centric Services
In this section we will first list a set of primary
services constituting the must of UNIC, that are
commonly gathered under the term of Triple Play
services. These are mainly entertainment services
using the TV set as a universal gateway for
consumers at home. They all present some
differences compared to the usual Triple Play
services offered today. Another set of services is
further defined to exploit the possibilities of UNIC
to provide new original features to consumer or to
extend them to business users.
The list of defined services is not exhaustive
neither it is supposed to be supported entirely by
the UNIC project. This list is solely intended to
provide a general overview of the possibilities of
UNIC in the context of TV evolution.
2.1 Real Triple Play
Beyond Internet services: Web2TV, Email2TV,
Chat2TV, Music Download/Playback, Online
Gaming, Home on Demand Gaming, Extreme
Online Role-Playing Game (XORGS) Audience,
Cyber-Gaming. Internet TV-centric services are
mostly intended for people who do not own
computers in order to make the World Wide Web
available to everyone.
Beyond TV services: SD/HD TV, Personal TV,
Interactive TV, Interactive TV return Channel,
Personal Video Recording (PVR), Time Shifting
(TS), Video on Demand (VoD), Electronic Program
Guide (EPG), Mosaic. Several of these are already
delivered by terrestrial and satellite Digital TV
providers using the current PSTN return channel for
interactive services. Exploiting the satellite return
channel combined with the DVB-S2 technology
will allow UNIC to be an attractive alternative.
Beyond phone services: Phone2TV, Video
Conferencing. The TV-Centric structure will ensure
that any person with a TV set can potentially
communicate with voice and/or video with one or
more other distant persons. These services already
exist on terrestrial broadband but require a
computer, a webcam and adequate video
conferencing software. Having a TV-Centric video
conferencing service available to any person
owning a TV would have a great impact on the
business context, considering that it provides a
turnkey solution for video conferencing.
2.2 More Services
Surveillance
and
monitoring
services:
Home/Office Surveillance/Automation, Weather
Monitoring, Crop Monitoring & Management. These
services are designed mainly for industrial
applications in developed area and to meet local
governments’ needs in rural areas in developing
world.
Tourism services: Interactive Travel Channel,
Virtual Cultural Visit (VCV), Real Estate Timeshare
Information, Nightlife Events Information, Weather
Forecast. It will be possible to access to tourism
information in remote areas lacking Internet
connection.
Other services: Bringing Courses Into Home, TV
All Together, Live Announcement, Assisted Living,
TV Health Centre. UNIC can give a large
contribution to the continuing trend of distance
learning and home-based care services reshaping
the way consumers use Digital TV.
2.3 Services requirements
The performance requirements of all services
from the user perspective were obtained similarly to
ITU G.1010 (2001) to take into account all aspects
of a service as it can be experienced by the user.
These requirements are network-agnostic and focus
on user-perceivable effects.
We exploited the QoS criteria commonly used
for IP data communication services to define the
QoS requirements for the particular services.
QoS criteria for IP data communication services
are based on the definition of parameters that allow
specification and assessment of the performance of
speed, accuracy, dependability and availability of
the IP data communication services. In the process
of IP packet transfer, the following event can take
place: successful transmission, loss and error.
We investigated the basic services establishing a set
of recommended values for each transfer
parameters. The QoS requirements must be fulfilled
to achieve sufficient service quality. We used these
basic applications as building blocks for the more
advanced services outlined in this section. For
instance, the Video Conference service requirement
is the combination of Conversational voice and
Videophone application requirements.
3. System architecture
The following
architecture:
picture
recalls
the
UNIC
Figure 1: UNIC Architecture
In the picture above, all interactive services (red
arrows) transit through the Collective Gateway
(CG). The CG is shared among users of the same
local network, so is the Satellite Modem and the
DVB-S2/DVB-RCS [5-7] connection over satellite.
Hence the end-user does not need a personal
satellite antenna for these interactive services as
they all transit over terrestrial connection (Ethernet
or WiFi) from the Set-Top-Boxes to the CG. This
architecture resembles the one of standard
terrestrial Triple Play service providers where the
CG, Satellite Terminal and antenna can be
compared to the DSLAM (Digital Subscriber Line
Access Multiplexer) except in the case of UNIC the
DSLAM is connected to the Internet Backbone via
Satellite and through the UNIC Platform.
One of the advantages of the UNIC architecture
over terrestrial Triple Play is that the television
service is provided Direct To Home (DTH) using
the power of broadcast via satellite with the
possibility to provide multiple real full HD
channels. For this service the end-user will require
a receive only satellite antenna (60-80cm) on
his/her own roof.
The UNIC System Platform is composed of four
segments:
• User /Home Service Segment
• Collective Service Segment
• Transport Media Segment
• Ground Service Segment
A. User/Home Service Segment
The UNIC User is intended as a non technical
single in-home user. The UNIC User accesses the
normal broadcasted programmes and UNIC
interactive services mainly from the television
equipment connected to the UNIC STB. The UNIC
User can also provide his own multimedia content
via mobile phone or PC to a central collection
point.
The UNIC STB is defined as the front-end device
that allows UNIC users to interact with the contents
and the services, providing appropriate user
interfaces, navigation tools and local storage.
The UNIC STB is a small box connected to the CG
on one side and to a television set on the other side.
There could be several STBs in the home, bringing
triple play services to multiple rooms. The STB is
responsible for dealing with users requests through
the remote control (additional user inputs to be
considered like webcam, microphone, etc.).
Requests are handled locally or transmitted to the
CG if a connection to the outside world is required.
The STB is also responsible for video and audio
output as well as application interfaces rendering to
television.
Motorola has developed the DVB STB subsystem.
The STB is the platform for the TV centric user
interactions and graphical interfaces for the UNIC
services provided by the STB Portal. The STB
consists of the following parts:
- STB Hardware: including CPU, storage, audio &
video codecs, external inter-faces, etc.
- STB HAL (Hardware Abstraction Layer)
including Linux Operating System, HW interface
library, drivers, etc.
- STB Application Platform including Application
services, web Browser and application program
interfaces (APIs) for both C++ and Java Script.
- TOIX UI Framework used for the development of
the STB Portal.
The STB Portal (see Figure 2) was developed by
Eutelsat using TOIX and the JavaScript APIs. The
STB Portal is an STB application providing the
graphical interface and utilising the functionality in
the STB subsystem.
Figure 2. The UNIC portal Homepage
B. Collective Service Segment
The Collective Service Segment (CSS) contains
all those components/functions providing services
to a community of users (i.e., the residents of a
multi-storey building or the inhabitants of a small
country village) connected to a bi-directional
satellite terminal. Since the satellite media is
particularly suitable for multi-casting applications,
local storage is a key function of the CSS to allow
high quality multimedia services and optimum use
of the satellite frequency resources. In case of
unicasting, the satellite segment provides ACM
functionalities (using the DVB-S2 standard) in
order to maximize the satellite capacity throughput .
The Collective Gateway (CG) is the core of the
CSS. The CG is the local unit of the platform
providing a number of functions available to all the
users connected to it. Components of the CG can be
described as follows:
The Captive Portal (CP) is the subsystem that
permits users to access to the built-in TV-Centric
Services.
The Local VoIP Gateway provides VoIP services
to the users. It is interconnected to the centralized
VoIP Gateway in the Service Operation Centre
(SOC) and provides access to the telephone
network using this peer system.
As per the VoIP subsystem also for web content
browsing a two level architecture has been chosen.
This means that when a user requests a web content
the request is automatically redirected to the Local
Web Server. If the page is already cached by this
system (e.g. already requested previously and not
yet expired) it is returned to the requestor with no
occupation of the satellite link. If the page is not
stored yet in the local cache the request is routed to
the centralized web proxy-cache and then, if needed
to the Internet.
The Local QoS Manager is in charge of deciding
the QoS policies to be applied for each client and
for the whole CG. It is interconnected with the
QoS-to-ACM Controller which is responsible for
remapping QoS requirements in ACM messages to
be sent to the peer system (QoS-to-ACM Actuator)
in the Service Operation Centre. QoS information at
application level are processed by the Local QoS
Manager that can decide to generate ACM
messages. The messages are prepared and delivered
by the QoS-to-ACM Controller.
The Multicast Content Delivery Client (with
Local Storage) subsystem receives contents
distributed in multicast, stores them on a local
storage area and makes them available to the STBs
and the client devices.
C. Transport Media Segment
The Transport Media Segment (TMS) provides a
communication network that supports multimedia
services over GEO bent pipe satellites. It includes
ground subsystems (hub, teleport for satellite),
communication infrastructure and local terminals.
The TMS is designed to complement the direct
satellite broadcast (one-way) audio and video
transmission channel with a bidirectional IP based
access system.
The satellite transport network comprises one
Gateway and a large number of Satellite Terminals
(ST) connected with the CSS or the HGW. It
supports star links between the Gateway and the
ST, but also ST to ST connectivity through the
Gateway.
The Gateway is the central component of the
network. It offers a connection to the UNIC
platform – and wherefrom external networks –
through its IP router. The Gateway handles the
traffic between the platform/external networks and
the STs and manages all access services. It provides
a powerful radio resource management, which
allows efficient utilization of the satellite capacity
with circuit and packet types of traffic.
The TMS is described here in a layer based
approach. The access layers are divided into the
following two links: the forward link, which
provides connectivity from the gateway to the STs,
based on the DVB-S(2) standards, and the return
link, which provides an MF-TDMA access scheme
offering cost-effective sharing for the return
bandwidth between the STs, based on the DVBRCS standard.
The access layers are sub-divided into the
physical layer (modulation, bursts), the layer 2
transport layer (ATM or Multiprotocol/Generic
Stream Encapsulation) and the Medium Access
Control (MAC) sub layer. The latter handles the
mapping and scheduling of higher layer flows onto
layer 2 transport means and it is an important part
of the end-to-end QoS enforcement.
At the transport layer, the segment also supports
a specific acceleration scheme in order to mitigate
the “high delay x bandwidth” adverse effect of the
satellite transmission channel on TCP connections.
D. Ground Service Segment
The Ground Service Segment (GSS) contains
the:
• Service Operation Center
• Multicast Content Delivery platform
• Integrated Value added Service
platform.
The GSS allows:
1) Independence from the actual service providers
making the UNIC platform ready to interoperate
with different “Existing Service Providers”, such as
mobile operators, IPTV broadcaster, etc.
2) Central provisioning and access of basic
services, making it easy to account and log services
and to monitor actual performances.
3) Integrated QoS Management specifically
designed to optimize the perceived QoS in the
collective scenario, and possibly work in
conjunction with the QoS management module at
level of TMS.
4) Easy integration of Value-Added Services, such
as Push VoD and User-Generated Content or other
service platform from external actors.
The Service Operation Centre (SOC) provides an
independent access to all the available transport
media as well as gateway to provide basic services
such as SMS/MMS, Email, Internet Access, VoIP
Gateway.
The Multicast Content Delivery platform is the
core of the content distribution system. It is a
hardware/software system designed to handle
robust and secure multicast content distribution
with no return channel. It is based on a Multicast
Delivery Framework (MDF), that is a general
framework for easy, robust, optimized and secure
multicast file delivery and has two main
components: MDF Server and MDF Client. The
MDF Server has the main role of file pushing
through the one-way multicast channel. In order to
allow an MDF client to receive the right and
expected file other synchronization information are
sent, called Electronic Service Guide (ESG). MDF
is optimized with full bandwidth control and group
management to send the same content to more than
one user, but not all the user.
The Integrated Value Added Service platform
allows the following processes to be applied to the
multimedia content: acquisition, storage, metadata
provision, transcoding and Digital Right
Management.
5. Conclusions
The above paper gives a description of the
interactive bidirectional satellite architecture being
developed in the UNIC project. Lab and home trials
phase is running throughout the first months of
2008, following a stepped scenarios approach. First
the delivery of basic IPTV services over satellite is
to be validated. Then, additional services (push and
forward solutions, content delivery) will be added.
Finally, more interactive service will be tried for
demonstration. At the end of the project, July 2008,
it is expected that the proof of concept platform will
show the potential of the TV-centric satellite
approach, using efficient standards, and leveraging
on terrestrial IP solutions, to bring to TV users in
remote areas an effective access into the digital
world.
6. References
G. Boccolini, B. Garnier, J.-M. Merour, A.
Brunelle, S. Titomanlio, V. Mignone, P.-O. Agne,
M. Luise, J.-P. Bucau, M.A. Sasse (2007) “UNIC:
A Novel Bi-directional Satellite Platform To
Provide Triple Play Services”, in Proc. 16th IST
Mobile and Wireless Communications Summit,
2007, Budapest, Hungary.
ITU G.1010 (2001) “Draft New Recommendation
G.QoSRQT – End-user Multimedia QoS
Categories”, ITU-T study group 12, contribution 37
Seager, W., Knoche,H., Sasse, (2007) M. A, "TVcentric triple play services: a requirements capture",
European Interactive TV Conference (EuroITV07)
May 24-25, 2007, Amsterdam, Holland.