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DVB-RCS2: Advancing TDM/TDMA

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DVB-RCS2: Advancing TDM/TDMA DVB-RCS2: Advancing TDM/TDMA HomeSolutionsIntroductionEducatione-GovernanceOil & GasISPs & TelecomsCorporate NetworksRetailMaritime & ShippingLand Mobile CommunicationsBankingProductsIntroductionSatLink Hub FamilySatLink VSATsSatLink 2000SatLink 2910SatLink 2910 MobileTechnologySatellite Technology for IPDVB-RCS2: Advancing TDM/TDMADVB-RCS & DVB-RCS2 StandardsOpen Hub ArchitectureServicesIntroductionCustomer SupportSystems IntegrationManaged NetworksTrainingTurnkey SatelliteAbout UsAbout UsMilestonesMarket PresenceNewsMain OfficeQuick Menu Sales & Marketing InquiriesPartners & Resellers    An NSSLGlobal Technologies Solution NSSLGlobal Technologies AS acquires SatLink resources in major network R&D investment...<read more> NewsContact Us HomeSolutionsTailored to your needsIntroductionEducatione-GovernanceOil & GasISPs & TelecomsCorporate NetworksRetailMaritime & ShippingLand Mobile CommunicationsBankingProductsManufactured by STMEAIntroductionSatLink Hub FamilySatLink VSATsSatLink 2000SatLink 2910SatLink 2910 MobileTechnologyHow does it work?Satellite Technology for IPDVB-RCS2: Advancing TDM/TDMADVB-RCS & DVB-RCS2 StandardsOpen Hub ArchitectureServicesHow can we serve you?IntroductionCustomer SupportSystems IntegrationManaged NetworksTrainingTurnkey SatelliteAbout UsWho are we?About UsMilestonesMarket PresenceNewsMain OfficeQuick MenuUseful LinksSales & Marketing InquiriesPartners & Resellers Print DVB-RCS2: Advancing TDM/TDMA Technology The predominance of TDM/TDMA in satellite networks today for interactive IP (Internet Protocol) communications illustrates the importance of this technology in furthering the reach of the Internet and for extending all kinds of private IP networks or VPNs into regions of the world poorly served by terrestrial communications. The portion of these networks where the greatest innovation is occurring is in the TDMA liaison from many remote VSATs (i.e., low-cost ground terminals) to one or increasingly inside sites or Hubs in a star topology, and to other VSATs (in a mesh topology). The bandwidth for transmissions from the VSATs is provided by a TDMA Carrier Group, which acts as a single pool of bandwidth shared by many VSATs. See the icon unelevated (as workable to a star topology).   Multiple Carrier Groups can be used if desired, with a single TDM forward link. A Carrier Group is managed by tenancy logic at the Hub using the concept of a "superframe" which defines and tracks all timeslots, on all TDMA carriers. For maximum efficiency, timeslots are prescribed exclusively to specific VSATs to implement all necessary "virtual channels" for user traffic, which must (ideally !) "float" dynamically wideness multiple TDMA carriers based on many fast waffly criteria well-expressed the network to reassure maximum link-level availability and multiplexing efficiency. Furthermore this must be washed-up with the necessary throughput, response time, and jitter performance for each of potentially many thousands of variegated IP traffic flows, based on a set of pre-defined "QoS Classes" (i.e., aggregates of IP traffic), which may be configured on a customized understructure for each VSAT in the network. NOTE: The same QoS policies and link-level availability requirements must moreover be met on the TDM forward link carrier (typically using DVB-S2 carriers with ACM), but it is much easier to implement that since all packet processing and tenancy over the forward ink is located in the Hub. Yet many TDM/TDMA suppliers do not yet integrate their QoS handling for each IP spritz with their implementation of ACM and how that impacts the virtual channels for these IP flows to each VSAT. The recently tried DVB-RCS2 standard – the 2nd generation of the well-established and widely unexplored DVB-RCS standards – is the most significant urging in TDMA burst-mode technology within the last 15 years. DVB-RCS2 sets a new benchmark that other TDM/TDMA network technologies – which are proprietary or non-standard – have yet to match. The specific nature of the TDMA technology for implementation these goals in satellite networks is tabbed dynamic MF-TDMA (Multi-Frequency TDMA). It is supported fairly widely in the industry, but not by all TDM/TDMA suppliers, as some lack the required dynamic flexibility. Dynamic MF-TDMA employs fast frequency hopping within the TDMA carrier group where the hopping wideness carriers occurs automatically in response to the needs of the network (i.e., not requiring human intervention). Dynamic MF-TDMA technology was standardized in the first version of the DVB-RCS standard in 2001. Today both standard (DVB-RCS) and proprietary versions of Dynamic MF-TDMA exist. But many suppliers lack the key features needed to produce the highest levels of efficiency, throughput, and reliability demanded by many customers. In particular, they lack the support of adaptive technologies for use in TDMA Carrier Groups (such as ACM) and they lack good modem spectral efficiency.   Adaptive MF-TDMA Technology: ACS and ACM perSplashThe two principal adaptive technologies for TDMA splash mode operation are: Adaptive Carrier Selection (ACS) per Burst: Dynamically selecting the carrier for a VSAT to use for its next TDMA burst, based on the carrier symbol rate, current conditions at the VSAT or the Hub (e.g., bad weather or interference), and as constrained by the VSAT hardware configuration. This helps reassure greater throughput and increased link reliability. Adaptive Coding and Modulation (ACM) per Burst: Dynamically selecting the MODCOD for a VSAT to use for its TDMA bursts, based on the same factors as above. This delivers the major wholesomeness for maximizing efficiency, as well as throughput and link reliability. Both of these technologies are supported by DVB-RCS2 and SatLink Communications' SatLink products. While ACS has been supported in SatLink Communications' SatLink networks for many years using first-generation DVB-RCS, the introduction of ACM per splash is a first with DVB-RCS2 shipments by SatLink Communications in 2012. No other TDMA technology or supplier provides DVB-RCS2 yet considering it requires major changes to their old and proprietary architectures. The support of "ACM per burst" on TDMA carriers can produce a 2x to 2.5x increase in the stereotype efficiency and throughput of those carriers in Ku or Ka wreath networks, while moreover profoundly increasing link-level reliability. When combined with ACS, remoter advantages are realized in throughput and reliability. For those many suppliers still without ACM or ACS the weightier mode of operation is to have all TDMA carriers in the Carrier Group run at the same symbol rate using a single stock-still MODCOD. This is in fact the requirement of some "dynamic" TDM/TDMA products from well-known suppliers. This prevents them from obtaining comparable efficiency, throughput, or reliability under worldwide network conditions, plane if they do sooner modernize their vital modem performance and support a wider range of modulation and coding options (MODCODs). NOTE: ACS is not a specific full-length of either DVB-RCS or DVB-RCS2, but rather a smart and very useful value-added full-length for managing a TDMA Carrier Group hands and well.   EvenIncreasinglyAdvancements with DVB-RCS2 DVB-RCS2 delivers many spare advancements that work in combination with ACM and ACS to produce the highest performance TDMA networks available. These include: Modulation and Coding Options (MODCODs) from QPSK 1/3 to 16QAM 5/6: These imbricate a range similar to DVB-S2 for TDM carriers, with "nominal" efficiencies up to 3.3 shit per symbol, using a 16-state Turbo Code FEC. LowSplashOverheads: All TDMA modems incur some splash overhead for baby-sit times, preambles and/or pilot symbols. The key is to reassure that these do not significantly reduce the nominal spectral efficiency by increasingly than a few percent, plane at upper symbol rates. Lower Carrier Spacing: In a DVB-RCS2 network, a spacing of 1.12x among TDMA carriers produces the optimal spectral efficiency (in bps/Hz), and the weightier efficiency of any splash modem, while matching or vibration the spectral efficiencies of the weightier "continuous mode" (e.g., TDM or SCPC) modems, plane without subtracting splash overhead and Layer 1 framing overheads. This holds true moreover when compared with DVB-S2 at its minimum 1.2x carrier spacing (with pilots and short-frames, as is worldwide when using DVB-S2 with ACM). Excellent Signal-to-Noise Ratio (SNR) Requirements: SNR requirements for DVB-RCS2 TDMA carriers are comparable (+/- 0.3 dB) to DVB-S2 TDM carriers for the same spectral efficiency at comparable FEC frame & splash sizes. MultipleSplashSizes: DVB-RCS2 defines several traffic splash sizes (which may moreover contain signaling information), a mini-burst defended to periodic and/or random wangle signaling, plus a special logon burst. All are specified in terms of symbols to simplify superframe customization and enable ACM. The traffic splash sizes indulge TDMA Carrier Groups to be optimized for the mix of IP packet sizes and/or the peak loading intensities expected at each VSAT.IncreasinglyEfficient IP Packet Encapsulation for Multiple IP Flows & Protocols: DVB-RCS2 replaces the previous standard methods of IP packet encapsulation with a new method tabbed "RLE" that is optimized for maximum efficiency in TDMA splash operation, profoundly reducing overhead on small IP packets where it matters most, and supporting multiple concurrent QoS Classes from a single VSAT as well as multiple IP versions (e.g., IPv4 & IPv6). Higher Symbol Rate TDMA Carriers: Maximum symbol rates for DVB-RCS2 carriers are not specified in the standard since they are implementation dependent. But the worthiness to tightly synchronize TDMA bursts in a DVB-RCS2 network (down to small fractions of a microsecond) minimizes required baby-sit times, and therefore reduces the penalty of going to higher symbol rates. This goal is moreover helped by the "Long Burst" and "Very Long Burst" options in DVB-RCS2 and the simplicity of the superframe. SatLink currently supports symbol rates on TDMA carriers up to 8 Msps (much higher than supported by other TDMA technologies) with the sufficiency for remoter increases as the market may demand. Large, Diverse TDMA Carrier Groups: The size and diversity of symbol rates with a TDMA Carrier Group is moreover implementation dependent. The DVB-RCS2 standard provides signaling structures that indulge a huge diversity and a very large number of carriers all in the same Carrier Group. Currently 24 TDMA carriers are supported in SatLink Hubs for the RCS2 superframes with both ACM and ACS active. In the future, up to 64 TDMA carriers will be hands supported for RCS2 on high-performance platforms. This increases efficiency, throughputs, and overall link reliability for all VSATs. See Creation of the Second Generation: DVB-RCS2 for increasingly information on the minutiae of this important new standard and to see a video re-creating the first live sit-in of DVB-RCS2 with ACM per splash for the European Space Agency. NOTE: Not all features of the DVB-RCS2 standard are supported in SatLink products today, but nearly all the major features (see above) are currently supported and many other useful ones will be supported in 2013 for the "linear" modem options as listed above. Interested in a SatLink® product or a solution or service? Please click here to send an inquiry. HomeSolutionsIntroductionEducatione-GovernanceOil & GasISPs & TelecomsCorporate NetworksRetailMaritime & ShippingLand Mobile CommunicationsBankingProductsIntroductionSatLink Hub FamilySatLink VSATsSatLink 2000SatLink 2910SatLink 2910 MobileTechnologySatellite Technology for IPDVB-RCS2: Advancing TDM/TDMADVB-RCS & DVB-RCS2 StandardsOpen Hub ArchitectureServicesIntroductionCustomer SupportSystems IntegrationManaged NetworksTrainingTurnkey SatelliteAbout UsAbout UsMilestonesMarket PresenceNewsMain OfficeQuick MenuSales & Marketing InquiriesPartners & Resellers Click on the undecorous pin to get directions to NSSLGlobal Technologies AS.   NSSLGlobal Technologies AS: Rolfsbuktveien 4B, N-1364Fornebu, Norway Contact: This email write is stuff protected from spambots. You need JavaScript enabled to view it. 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