Home >> June 2013 Edition >> SatBroadcasting™: S2 Extensions Demystified
SatBroadcasting™: S2 Extensions Demystified
By Koen Willems, Strategic Marketing Director, Newtec


DVB-S2 is the most accepted and widely spread standard in the satellite market. The standard has a deep market penetration in Sports and News Contributions, Professional Video Distribution solutions, IP trunking and Cellular Backhauling, Broadband VSAT solutions including Government and Defense networks over satellite.

WillemsFig1 In a fast moving satellite world, new technologies (HTS, HEVC, UHDTV) emerge and data rates increase at an accelerated pace. Within applications such as Contribution and IP Trunking, the efficiency requirements are already testing the limits of the DVB-S2 standard. The risk for a massive take-over by proprietary technologies with better performance is realistic. A proprietary scenario would disperse the satellite industry, increase the cost of satellite communications as well as prevent interoperability and result in vendor lock-in.

A new standard (or extension to DVB-S2) with improved efficiency will give the satellite industry more breathing space to increase profitability and allow for business growth throughout all applications, from High Speed IP to Broadcast to VSAT.

Callout1 The efficiency technologies contributed by Newtec to the new DVB standard boost the satellite link as much as 20 percent in Direct-To-Home (DTH) networks, and 36 percent in other professional applications when compared to DVB-S2. These gains already exceed the results by proprietary systems in the market today.

Introduction
Kick-started by Newtec earlier this year, key players in the satellite industry are calling for a new satellite transmission standard, specifically for professional satellite contribution links, which would extend the existing DVB-S2 standard.

The satellite world has changed a lot since DVB-S2 was first published in 2005. Higher speeds, more efficient satellite communication technology and wider transponders are required to support the exchange of large and increasing volumes in data, video and voice over satellite. The biggest demand for the extensions to the DVB-S2 standard comes from video contribution and high-speed IP services, as these services are affected the most by the increased data rates.

In the long run, more throughput will be required for DTH applications as well with the rise of Ultra-High Definition TV (UHDTV) and the High Efficiency Video Coding (HEVC) video compression standard to support the request of higher quality images by the market.

Callout1 Ultimately, for satellite businesses, the creation and adoption of these extensions will translate to higher efficiency, higher speed and greater service robustness to increase business and, therefore, revenues.

Many vendors, operators and satellite specialists within the industry agree with DVB and are working towards these new extensions. As the official naming by DVB has not been decided yet, we will refer to the bundle of improved candidate technologies for the new standard as S2 Extensions.

The Market Is In (R)evolution

Satellite’s Challenge Versus Fiber
Changes have never occurred so rapidly in the satellite industry as they are today. The increasing penetration of terrestrial communication alternatives has placed satellite under pressure.

A common misconception is that fiber will entirely replace satellite sooner or later. Use cases, economic considerations and new technologies prove that satellite still has value for years to come. Terrestrial and satellite communications are more likely to cohabitate in network structures and will be selected depending on the application.

Breakthrough Technologies Change The Game
High Throughput Satellites (HTS) and efficiency technologies have changed the game. More bandwidth capacity will become available and prices per megabit will drop. Both HTS and efficiency technologies blow oxygen into satellite service providers’ profitability and growth.

Efficiency technologies allow for more throughput in the same bandwidth or to save on OPEX. In technical terms, efficiency technologies push more bits through the same Hertz.

What can be done with these extra megabits? Examples throughout different applications demonstrate the benefits:

In a VSAT environment more users can be added to the network resulting in extra revenue. Higher SLA’s become possible increasing the user experience.
Broadcasters can add more TV channels to their offering and increase the quality of the image.
Extra revenues can be achieved by adding services in a multiservice context.


WillemsFig2 Why Standards?
In the satellite industry there will always be a field of tension between open standards and proprietary technologies. Although in the short term proprietary technologies might be the best option to acquire quick revenues, in the long run the availability of open standards will benefit the entire satellite industry for the following reasons:

The impact of standardization increases the quality of life in both developed and developing countries. Standards for satellite communications allows people to connect all over the world to the information highway to give them better access to education, to (welfare) services, to economical, political and social involvement.

Which Markets Will Quickly Adapt To S2 Extensions?
The satellite industry has come to a consensus that a successor to the DVB-S2 standard is required to accommodate for increased profitability, interoperability and growth in the professional satellite communications market.

Newtec has taken the lead and teamed with other DVB-members in order to define and develop the update on the DVB-S2 standards. The current DVB-S2 standard has served the industry well, but it is now close to 10 years old.

To learn more on how the market perceives the introduction of the new S2 Extensions standard, go to the Newtec website and download the E-book with the S2 Extensions Survey results by 700 SATCOM experts: www.newtec.eu/technology/s2-extensions.

WillemsFig3 Up until now, the DVB-S2 standard has been the solution for a wide scope of applications over satellite including distribution applications such as DTH. For distribution activities, broadcasters are likely to continue to use the existing DVB-S2 standard for some time to come. However, with the new, higher resolution technologies such as UDHTV and HEVC video compression about to hit the market, and the drive for more content, in the longer term the new S2 Extensions will be adopted for DTH networks as well.

We are likely to see an immediate take-up, in applications that require high throughput over satellite for professional use and in applications that suffer for bandwidth or need better margins to remain profitable. The applications that will adapt quickly to the S2 Extensions are:

– IP Trunking & IP/Telecom Backbones
– Broadcast Contribution and Exchange
– IP Backhauling & Professional IP Access
– Government High Speed Communications and Disaster Recovery
– Multi-Service networks over satellite


The Innovations Behind S2 Extensions
The successor to the DVB-S2 standard is a combination of innovative technologies that improve overall efficiency over satellite links.

These technologies and their intrinsic benefits will be described in more detail in the sections below.

Callout3 Smaller Roll-Offs + Advanced Filtering Technologies
The new S2 Extensions include a combination of smaller roll-offs (5, 10, 15 percent) and introduces advanced filtering technologies to allow optimal carrier spacing. Compared to DVB-S2 the combination brings efficiency gains up to 15 percent.

Improvement 1: Smaller Roll-Offs
A first innovation inside the new standard implements a smaller Roll-Off (RO) percentage than currently used in the DVB-S2 standard. In the DVB-S2 standard, the 20 and 25 percent RO percentages are common and are an integral part of the modulated carrier (i.e., symbol rate plus RO).

Reducing Roll-Offs to 5, 10 and 15 percent results in a direct gain in bandwidth. Looking at the spectral image when implementing smaller ROs, the slope of the carrier becomes steeper compared to DVB-S2 but still fits nicely in the allocated bandwidth.
The efficiency gain by implementing smaller roll-offs can increase to 15 percent. When implementing smaller roll-offs every network and/or link needs to be checked individually, as immediately switching towards 5 percent RO does not always bring the best efficiency. In some cases, 10 percent roll-off will afford better results.

Improvement 2: Advanced Filtering Technologies for Improved Carrier Spacing
The second innovation deals with noise levels (side lobes) on both sides of the carrier. These side lobes prevent putting satellite carriers close to one another. Applying advanced filter solutions has an immediate effect on bandwidth savings, as the spacing between carriers can be put as close as 1.05 times their symbol rates (or even closer in some specific use cases).

It is important to note that even with 35, 25 and 20 percent ROs, better filtering results are obtained. The improvement has the best effect when the ground station High Power Amplifier (HPA) is driven close to saturation. The spectral regrowth at a frequency offset (= symbol rate) will be lower with the better filtering. Meaning, at saturation the result will have a much cleaner signal spectrum.

Improvement 3: Supporting Different Network Configurations
The RO and filtering innovations within the new standard can be applied in satellite links with single carriers (mainly RO effect), multiple carriers (Filtering and RO effects) or carriers sharing the same transponder with other providers. In the latter case, S2 Extensions carriers can easily coexist with adjacent carriers from other operators within the same transponder. The improved ROs and filtering technologies are only applied on the allocated carriers. Neighboring carriers will not be affected and do not notice any form of interference.

S2 Extensions MODCOD and FEC Upgrades

Improvement 4: Increased Granularity in MODCODs
As a next step, the S2 Extensions increase the modulation and coding (MODCOD) schemes and Forward Error Correction (FEC) choices when compared to DVB-S2.

WillemsFig4 By introducing an increased granularity, the highest resolution for optimal modulation in all circumstances can be provided. The current DVB-S2 quantization steps are quite far apart. By adding granularity in the upcoming standard, the service provider can further optimize the satellite link depending on the application. In combination with Adaptive Coding and Modulation (ACM), where the highest MODCOD is selected automatically, full efficiency can be gained. The amount of MODCODs has grown from 28 in DVB-S2 up to 87 in the S2 Extensions, bringing efficiency as close to the theoretical Shannon limit as possible.

Improvement 5: Higher Modulation Schemes Up to 64APSK
Adding higher modulation schemes such as 64APSK proves to be useful considering the professional applications that work with improved link budgets provided by, for example, bigger antennas (more powerful satellites that become available). Newtec sees the 32APSK boundary being reached frequently with its auto-adaptive FlexACM® technology during clear weather conditions. In these situations 64APSK is highly beneficial. When combining the increased granularity (MODCODs and FECs) and 64APSK (higher order modulation and coding) immediate efficiency gains up to 37 percent can be achieved when compared to DVB-S2 (see figure below).

Improvement 6: Different Classes for Linear and Non-Linear MODCODs
Different to DVB-S2, the MODCODs in the S2 Extensions have two different classes for linear and non-linear MODCODs. Since the DVB-S2 MODCODs are focused on DTH, the constellations are well suited for distribution applications with quasi-saturated transponders. For high-speed data and contribution applications other constellations can be considered where the performance gain is larger than 0.2dB.

Although the MODCODs might use the same code/name, the linear and non-linear MODCODs are not interchangeable. Additionally the MODCODs and FECs themselves have been improved compared to the DVB-S2 standard to achieve even better efficiency levels.

Wideband

Callout4 Improvement 7: Wideband Support up to 72 Mbaud
The S2 Extensions support technology for typical wideband transponders that become/are available today hosting high-speed data links.

The wideband implementation (up to 72 Mbaud) in S2 Extensions typically addresses satellite transponders with bandwidths from 72MHz (typically C-band) up to several hundred MHz (Ka-band, HTS). In principle it would be possible to allocate several narrower, channels inside the wideband transponders, but this would require the operation of the satellite transponder with reduced downlink power and therefore at sub-optimal efficiency. The S2 Extensions demodulator will receive the complete wideband signal up to 72 Mbaud resulting in a very high data rate. The introduction of the wideband technology adds extra 20 percent efficiency gain.

S2 Extensions Technology Results
As illustrated in the figure, DVB-S2 with 20 percent RO is compared with S2 Extensions and 5 percent RO. The main efficiencies are located in the higher MODCODs. Herein resides the reason why the S2 Extensions standard first targets data rate hungry applications such as Broadcast contribution and exchange, TSoIP Contribution and Primary Distribution, IP backbones and IP Trunking related configurations (IP Access, IP Backhaul, Government high speed communications).

WillemsFig5 Newtec Implementation Of The S2 Extensions
The smaller ROs and advanced filtering technologies were already introduced by Newtec as early as September 2011 as a first step towards the new S2 Extensions standard through Newtec’s Clean Channel Technology®, which is available on Newtec’s professional equipment, both as a software field upgrade for installed based equipment as well as new Newtec equipment.

In the meantime, Newtec has invested a lot in its innovative technology to add to the new S2 Extensions standard. Newtec’s contribution to the new S2 Extensions standard has resulted in the technology candidates that are already implemented on Newtec’s newest family member, the MDM6000 Satellite Modem. The modem integrates all S2 Extensions innovations on board, from smaller ROs, advanced filtering, MODCODs and FEC upgrades to wideband support.

On top of the DVB-S2 Extensions the MDM6000 modem can be used in combination with technologies such as Adaptive Coding & Modulation (ACM), Pre-distortion, bandwidth cancellation, network optimization software and cross-layer optimization to bring the efficiency of the satellite link to the highest level at maximum service availability.

How to Increase Efficiency + Availability Of A Satellite Link On Top Of S2 Extensions


Callout5 Adaptive Coding & Modulation
Adaptive Coding & Modulation (ACM) auto-adaptively sets modulation parameters to the optimal point to overcome fading or interference conditions and allows for the best possible throughput.
Newtec’s implementation of ACM, called FlexACM®, combines the adaptive modulation with noise and distortion estimation technology (NoDE) and predictive technology on upcoming variation (ThIMM) to get as close to the zero margin limit as possible allowing the full use of the satellite link at maximum service availability.

Pre-Distortion Technology
Pre-distortion technologies are typically designed to compensate for the effects of imperfections in the filters and amplifiers of the satellite.

Newtec’s implementation of pre-distortion technology, Automated Equalink®, improves the performance of the end-to-end satellite communication channel by a typical 2dB and allows the use of higher modulation schemes such as 16/32APSK or 64APSK on carriers occupying a full transponder.

Newtec’s Equalink® brings up to 10 percent bandwidth efficiency gain, even in saturated non-linear transponders (which is the use case for very high speed links). Moreover a better Quality-of-Service (QoS) can be achieved.

Bandwidth Cancellation
Bandwidth Cancellation Technology combines the forward and return transmissions in the same satellite bandwidth opening up extra capacity (up to 33 percent) for the service provider. This extra capacity gives room for considerable OPEX savings or deployment expansions by adding services within the same available bandwidth.

WillemsFig6 Cross-Layer Optimization™
Cross-Layer-Optimization™ is the technology that allows the satellite modulation equipment to be in continuous interaction with Acceleration, Compression, Bandwidth Management and IP Shaping technology. As soon as a satellite link condition changes, the link will be auto-optimized following Quality-of-Service (QoS) and Priority Settings without the loss of data or link.

Conclusion
The satellite industry has come to a consensus that a successor to the DVB-S2 standard is required to accommodate for increased profitability, interoperability and growth in the professional satellite communications market. Newtec has taken the lead and teamed up with other DVB-members in order to define and develop the update on the DVB-S2 standard.

Applications such as Sports and News Contribution, IP trunking and Cellular backhauling up to Broadband VSAT solutions will immediately benefit from the gains achieved by the new standard. As soon as Ultra High Definition TV hits town and more content is required by the market, the Professional Video Distribution and DTH applications will quickly follow.

Callout6 Newtec’s contribution to the new standard (naming still to be decided by the DVB organization) consists of a number of efficiency technologies, such as...

Smaller Roll-Offs
Advanced filter technologies
Increased granularity in MODCODs
Higher Modulation (64APSK)
Wideband (72 Mbaud)


By combining these technologies an efficiency optimization up to 37 percent can be obtained in a professional satellite link. Adding wideband to the equation adds another 20 percent gain.

The Newtec MDM6000 Satellite Modem integrates the candidate technologies combined with Newtec efficiency technologies (FlexACM®, Equalink®, Bandwidth Cancellation and Cross-Layer-Optimization™) and guarantees the best performance with barrier-breaking throughputs at optimal service availability.

For further information, please visit Newtec’s online page at: http://www.newtec.eu/technologies/s2extensions

Also, download the results of the Survey on S2 Extensions, with the results by 700 SATCOM experts from 400 different companies at: http://www.newtec.eu/technology/s2-extensions .

WillemsHead About the author
Koen Willems starts his career in 1998 with Lernout&Hauspie, as project manager in the Consulting & Services division. More recently he joins Toshiba as a Product Marketing Manager for the Benelux and later for the European market. In a total of 6 years Koen contributes to all major Toshiba Retail IT product releases. Mr. Willems is, at present, Product Marketing Director Mobile TV and Digital Terrestrial TV Equipment for Newtec, a Belgium-based specialist in satellite communications. Koen holds a degree in Germanic Languages (University Ghent, Belgium, 1997) and completed a Master in Marketing Management program at the Vlekho Business School in Brussels (1998). He acquires a Six Sigma Black Belt for product development and process improvement in 2006.



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