O slideshow foi denunciado.
Utilizamos seu perfil e dados de atividades no LinkedIn para personalizar e exibir anúncios mais relevantes. Altere suas preferências de anúncios quando desejar.

Comtech sspi vsat_day_2009

130 visualizações

Publicada em

Comtech - Advanced FEC and Modcodes for Optimizing Satellite Links

Publicada em: Tecnologia
  • Seja o primeiro a comentar

  • Seja a primeira pessoa a gostar disto

Comtech sspi vsat_day_2009

  1. 1. Optimizing SCPC Technologies to Address the Satellite Capacity Shortage Welcome to Comtech Technology Seminar
  2. 2. SatCom Economics – “Total Cost of Ownership” • Costs typically associated with satellite communications – Operating expenses Satellite space segment Recurring license fees and taxes Support and maintenance – Capital (Fixed) expenses Ground equipment, codec, routers, switching equipment, modems, converters, RF, HPA, antennas Site preparation, civil works, one time license fees • What does a SatCom user want? – Reduce Operating Expenses (OPEX) Reduce occupied bandwidth Reduce transponder power – Reduce Capital Expenses (CAPEX) Reduce BUC/HPA size Reduce antenna size – Increase availability (margin) – Increase throughput 2 Operating Expenses Capital Expenses Network Operations + Depreciation Total Cost of Ownership Operations & Maintenance Transmission OPEX Power Spares/Support Training Site Rental Network Equipment Site Equipment Civil Works NRO Transmission Equipment
  3. 3. Traditional SatCom Optimization • Traditionally, you could reduce bandwidth or power, but not both without significantly increasing the CAPEX – Reduce occupied bandwidth Use higher order modulation – Increases transponder power utilization – Increases BUC/HPA size and/or antenna size – Reduce transponder power utilization Use lower order modulation – Increases occupied bandwidth – Reduces BUC/HPA size and/or antenna size Without using lower order modulation – Increase antenna size 3
  4. 4. Revolutionary Forward Error Correction & Modulation Low-Density Parity-Check Codes (LDPC) • At lower code rates (≤ Rate 3/4 ) gives better performance than Turbo Product Coding • Can acquire and track at much lower values and Eb/No 5
  5. 5. 6 Modulation and Coding – DVB-S2 – Goals Increase throughput over same transponders Advanced capabilities for one-way and interactive applications – Results: 30% more throughput for same transponder EIRP and BW with constant modulation and coding Change modulation and coding on the fly for advanced applications and services – Modulation and Coding Implementation QPSK, 8-PSK, 16-APSK and 32-APSK modulation Code rates 1/4 to 9/10 using LDPC + BCH error correction – LDPC = Low Density Parity Codes – BCH = Bose-Chasudhri-Hocquenghem C/N (ideal) from -2.4 (QPSK 1/4) to 16 dB (32-APSK 9/10) 6
  6. 6. VersaFEC® • VersaFEC is a patented (Covered by US Patents 7,353,444 and 7,415,659. System of short-block, low latency Low Density Parity Check (LDPC) codes designed to support latency-sensitive applications, such as cellular backhaul over satellite. – VersaFEC was developed by Comtech AHA in collaboration with Comtech EF Data • Requires optional expansion card – Can be field installed by a qualified technician VersaFEC is a Trademark of Comtech AHA 7
  7. 7. Why VersaFEC ? • For block codes such as Turbo Products Codes (TPC) or Low Density Parity Check Codes (LDPC) the coding gain improves with increased block size, however increasing the block size leads to increase in latency. • So, the 1.0 dB improvement in Eb/No came at the expen ses of almost 5 fold increase in latency. • VersaFEC is designed to provide high coding gain with much lower latency so latency sensitive applications can take advantage of the improved gain. 8
  8. 8. VersaFEC Modulation & Code Rates • VersaFEC supports 12 different modulation and code rates for ACM and CCM 9
  9. 9. Is FEC Latency Fixed ? • For block codes such as TPC, LDPC, VersaFEC, DVB-S2, latency is inversely proportional to the data rate, if the data rate doubles, the latency is reduced by 50%. • This is why a low latency FEC is critical for lower data rate links. 10
  10. 10. Low Latency • VersaFEC was specifically designed to support low latency applications while providing superior coding gain – e.g. Consider a 256 kbps link using 8-QAM, Rate 3/4, needing a BER of 5.0E-8 In this case, VersaFEC’s Eb/No performance is as good as LDPC with 76% lower latency and 4% improvement in spectral efficiency Given the excellent Eb/No performance of VersaFEC, it is recommended for all supported data rates 11
  11. 11. Adaptive Coding & Modulation • Satellite users have traditionally relied on worst case link margin to overcome rain fade and other dynamic impairments which leads to significant inefficiencies • A Constant Coding and Modulation (CCM) link is generally over provisioned by many dBs of margin throughout the year, just to get through a few hours of excessive degradation. • CCM Link – Modulation and FEC Rate are set manually and remain unchanged until changed by the. 16
  12. 12. Adaptive Coding & Modulation • Adaptive Coding and Modulation (ACM) is a technique that allows for automatic change in Modulation and FEC Code Rate in response to changing link conditions. • Adaptive Coding & Modulation (ACM) converts the fade margin into increased capacity – average throughput gain of 100% (or more) is possible, compared to traditional CCM – This is accomplished by automatically adapting the modulation type and FEC code rate to give highest possible throughput. • ACM maximizes throughput under all conditions – rain fade, inclined orbit satellite operation, antenna mispointing, noise, interference and other impairments. 17
  13. 13. DoubleTalk Carrier-in-Carrier Bandwidth Compression
  14. 14. DoubleTalk® Carrier-in-Carrier® • Based on patented “Adaptive Cancellation”, Carrier-in- Carrier (CnC) allows carriers in a Duplex satellite link to occupy the same transponder space Without DoubleTalk Carrier-in-Carrier With DoubleTalk Carrier-in-Carrier Carrier-in-Carrier is a Registered Trademark of Comtech EF Data DoubleTalk is a Registered Trademark of Applied Signal Technology, Inc. 19
  15. 15. Use Spreading When Traditional Link is Balanced OR Power Limited 20
  16. 16. Multi Dimensional Optimization • DoubleTalk Carrier-in-Carrier is a bandwidth compression solution based on patented “Adaptive Cancellation” technique that allows satellite carriers to share spectrum • DoubleTalk Carrier-in-Carrier combined with proper Modulation and FEC, makes it possible to optimize satellite communications like never before – Reduce OPEX Occupied Bandwidth & Transponder Power – Reduce CAPEX BUC/HPA Size and/or Antenna Size – Increase throughput – Increase link availability – Or a combination to meet different objectives 21
  17. 17. Carrier-in-Carrier • CDM-625 has the most advanced Carrier-in-Carrier implementation • Significant Performance Enhancements – Improved Eb/No Performance – Ability to handle higher asymmetry – Improved Doppler performance – Additional optimization options when combined with LDPC/TPC and VersaFEC • Power ratio based on Power Spectral Density and not absolute power – PSD Ratio Spec (Interferer to Desired): -7 dB to +11 dB 22
  18. 18. Upgrading Balanced Link (Using CDM-625) • IS-905 – C-Band (EH) • Earth Station – 7.2 m to 3.8 m (Africa) 23
  19. 19. Upgrading Asymmetric Antenna Link (Using CDM-625) • IS-1002, C-Band (SEZ) • Earth Station – 9.0 m to 2.4 m (Africa) • Option 1 - Using different Modulation and FEC rate to keep PSD Ratio within specification • Power Spectral Density Ratio ~ ±5.5 dB (well within spec) 24
  20. 20. Upgrading Asymmetric Antenna Link (Using CDM-625) • Option 2 – Using same FEC and Modulation in each direction, but increasing Transmit EIRP of the smaller Antenna (if possible) to achieve similar PSD Ratio • Increasing Remote’s TX EIRP by 1 dB, allows similar Power Spectral Density Ratio as previous example 25
  21. 21. Upgrading Asymmetric Data Rate Link (Using CDM-625) • IS-905, C-Band (Global Beam) • Earth Station – 9.5 m to 3.8 m (Middle East/Africa) 26
  22. 22. CDM-625 Advanced Satellite Modem • CDM-625 Advanced Satellite Modem builds on Comtech EF Data’s legacy of providing the most bandwidth efficient satellite modems – First modem to support DoubleTalk® Carrier-in-Carrier® with LDPC and VersaFECTM (short block LDPC) FEC Provides significant OPEX and CAPEX savings compared to any other modem 27
  23. 23. Carrier-in-Carrier + VersaFEC/ACM • The CDM 625 Modem is the Most Spectral Efficient satellite modem on the market today – VersaFEC/ACM can deliver more then 100% traffic throughput increase – Carrier-in-Carrier can reduce satellite Power and/or Bandwidth resources by 50% 28
  24. 24. TPC / LDPC FEC + Carrier-in-Carrier Savings Compared to DVB-S2
  25. 25. CDM-625 Value Proposition • Combination of DoubleTalk Carrier-in-Carrier and LDPC – Additional reduction in Transponder Power – Additional increase in Margin (availability) – Further reduction in BUC/HPA and/or Antenna • CDM-625 can handle higher asymmetry – No restriction on symbol rate of the 2 carriers – Power Spectral Density Ratio limit as opposed to Total Power Ratio
  26. 26. Recent Customer Savings Examples • New Network in South Asia – 175 MHz (Traditional) vs. 125 MHz (CnC) Annual Savings ~ $600,000 (@ $1,000 / MHz / Month) • Existing Network in Africa – 40% potential saving on 1st transponder (36 MHz) Annual Savings ~ $520,000 (@ $3,000 / MHz / Month) – 44% potential saving on 2nd transponder (54 MHz) Annual Savings ~ $800,000 (@ $2,800 / MHz / Month) • Existing Network in Latin America – 38% potential saving on 1st transponder (41 MHz) Annual Savings ~ $486,000 (@ $2,600 / MHz / Month) 35
  27. 27. WAN Link Optimization
  28. 28. CDM-570/L-IP • Enables bandwidth efficient IP connectivity over satellite – Managed Switch capability for simplified set up – Static IP routing for unicast and multicast – Options for improving bandwidth efficiency Header Compression Payload Compression – Quality of Service (QoS) Option DiffServ Max/Priority Min/max – 3xDES data encryption option – Manageable via CLI, SNMP, web interface or telnet • Optional integration with Vipersat Management System (VMS)
  29. 29. VLAN Support (CDM-570/L-IP) • Native and Tagged Mode • Ingress/Egress processing based on user configuration – Up to 32 VLANs can be specified • VLAN QoS – Priority based with option to limit maximum
  30. 30. Header & Payload Compression (CDM-570/L-IP) • Header Compression – Reduces the Layer 2/3/4 header to a few bytes E.g., in case of Voice over IP (VoIP) bandwidth required can be reduced by as much as 60% – Configurable on a per route basis – Ethernet headers are compressed in easyConnect Mode • Payload Compression – Can reduce payload size by 40% or more – Configurable on a per route basis Supported Ethernet Headers (Header Comp.) Ethernet 2.0 Ethernet 2.0 + VLAN-tag Ethernet 2.0 + MPLS 802.3-raw 802.3-raw + VLAN-tag 802.3 + 802.2 802.3 + 802.2 + VLAN-tag 802.3 + 802.2 + SNAP 802.3 + 802.2 + SNAP + VLAN-tag 802.3 + 802.2 + SNAP + MPLS Supported Layer 3&4 Headers (Header Comp.) IP TCP UDP RTP (Codec Independent)
  31. 31. Quality of Service (QoS) (CDM-570/L-IP) • Minimizes jitter and latency for real time traffic • Provides priority treatment to mission critical applications • Allows non-critical traffic to use the remaining bandwidth • Modes – DiffServ Allows Differentiated Services in accordance with Industry standards – Max/Priority Assign maximum bandwidth that any traffic flow can utilize Establish up to 8 levels of prioritization – Min/Max Set the minimum and maximum bandwidth for user-defined classes of traffic Ensures that a certain level of bandwidth is always applied
  32. 32. WAN Adaptation • WAN adaptation capability reduces the satellite bandwidth required to carry an E1 bearer when used for cellular backhaul • Cellular protocols were originally designed to use entire E1 bearer(s) irrespective of actual traffic • WAN Adaptation reduces the bits that need to be transmitted, significantly reducing the transmission bandwidth – Possible savings of 30% or more depending on traffic profile 42
  33. 33. Modem Configuration • WAN Adaptation feature allows users to control savings and link quality • Terrestrial Input – E1 Balanced/Unbalanced – Select up to 16 Time Slots carrying traffic • WAN (Satellite) Output – Configure Modem Tx Data Rate The Modem Tx Data Rate can be as low as 0.5 x N x 64 kbps, where N is the number of selected traffic Time Slots E.g. if user selects 8 Time Slots as input, the Tx Data Rate can be selected from 256 kbps (50%) to 512 kbps (100%) 43
  34. 34. Adaptation Ratio & Savings • Adaptation Ratio is the ratio of the Modem Tx Data Rate and the Data Rate of the selected Time Slots – E.g. if 10 Time Slots are selected and Modem Tx Data Rate is set to 448 kbps Adaptation Ratio = 448/ (10 x 64) = 0.7 • % BW Savings = (1 – Adaptation Ratio) x 100 – E.g., in previous case, Savings = (1 – 0.7) x 100 = 30% 44
  35. 35. WAN Adaptation Savings 46
  36. 36. WAN Utilization 47
  37. 37. Link Congestion/Quality 48
  38. 38. Availability & Ordering • WAN Adaptation is available on E1/T1 capable CDM-570/L and CDM-570/L-IP • Plug-in hardware module – Can be installed in existing modems (that are E1/T1 capable) by a qualified technician Also requires firmware upgrade to 1.7.0 (or later) – Uses the Reed Solomon slot in the modem i.e. Reed Solomon cannot be ordered/used with WAN Adaptation • No software options/FAST required 49