Vsat day-2008-comtech
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This document discusses technologies for efficiently utilizing limited satellite bandwidth resources. It describes how spectral efficiencies can be improved through advances in forward error correction coding, such as turbo product coding and LDPC, which allow higher order modulations to be used at a given signal-to-noise ratio. It also discusses dynamic SCPC technology which provides automated allocation of bandwidth on satellite links based on application requirements, improving bandwidth utilization over fixed SCPC allocations. The Vipersat system is presented as a solution that combines TDM, TDMA, and dynamic SCPC technologies.
Vsat day-2008-comtech
- 1. ADVANCED COMMUNICATION SOLUTIONS SpectralSpectral EfficienciesEfficiencies Making the Most of aMaking the Most of a Limited ResourceLimited Resource Steve GoodSteve Good Director, Sales EngineeringDirector, Sales Engineering
- 2. Agenda • Satellite Network Service Levels • Total Cost of Ownership • Spectral Efficiencies • Point-to-Multipoint Satellite Technology Options • Vipersat Overview
- 3. Service Level Agreement (SLA) … defined as a combination of: Burstable Rates Committed Information Rate (CIRs) Oversubscription Quality of Service (QoS) Latency Jitter
- 4. What is a “1 Mbps Service”?? • 1 Mbps dedicated outbound, 1 Mbps dedicated inbound • 1 Mbps dedicated outbound, 256 kbps dedicated inbound • 1 Mbps shared (5:1) outbound with 256 kbps CIR, 256 kbps shared (5:1) inbound with 32 kbps CIR • 1 Mbps shared (10:1) outbound with 128 kbps CIR, 256 kbps shared (10:1) inbound with 16 kbps CIR • 1 Mbps shared (25:1) outbound with no CIR, 1 Mbps shared (25:1) inbound with no CIR • 1 Mbps shared (100:1) outbound with no CIR, 256 kbps shared (100:1) inbound with no CIR
- 5. Satellite Network Economics “Total Cost of Ownership” • Operating Expenses (OPEX) Satellite space segment Teleport operations Licensing • Capital Expenses (CAPEX) – Remote Indoor Kit Outdoor Kit – Hub Equipment Indoor Kit – Ground equipment, routers, switching equipment Outdoor Kit – Converters, RF, HPA, antennas OperatingOperating ExpensesExpenses CapitalCapital ExpensesExpenses Network Operations + DepreciationNetwork Operations + Depreciation Total Cost of OwnershipTotal Cost of Ownership Operations & Maintenance Transmission OPEX Power Spares/Support Training Site Rental Network Equipment Site Equipment Civil Works NRO Transmission Equipment
- 6. Bandwidth vs. Power Relative Bandwidth (%) – for same data rate -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 16QAM 7/816QAM 7/8 16QAM 3/416QAM 3/4 8PSK 5/68PSK 5/6 8PSK 2/38PSK 2/3 QPSK 7/8QPSK 7/8 QPSK 3/4QPSK 3/4 QPSK 1/2QPSK 1/2 QPSK 1/2 = 100%
- 7. Bandwidth vs. Power • Allocated BW – Portion of transponder actually used – Linear function of modulation and FEC – Decreases with higher order mods and FECs – “Bandwidth Limited” links have greater allocated than PEB • PEB – Fraction of transponder power required to close link – Complicated function of hub antenna, remote antenna and satellite specifics along with required Eb/No – Increases with higher order mods and FECs – “Power Limited” links have greater PEB than Allocated
- 8. Claude Shannon • “The Father of Information Theory” • A Mathematical Theory of Communications (1948) • Defined Channel Capacity • Information Entropy • “The Shannon Limit” • “Source Encoding” FEC • Store each possible message in the receiver Infinite memory and processing
- 9. The Quest to Reach Shannon’s Limit • 1980s Viterbi algorithm • Early 1990s Viterbi algorithm with Reed Solomon • 1999 Turbo product coding (TPC) • 2005 Low Density Parity Check (LDPC)
- 10. Spectral Efficiency vs. Eb/No
- 11. Turbo Product Coding (TPC) • Turbo Product Coding – Lower Eb/No requires less power – Higher efficiency uses less bandwidth 4.0 1.50 3/4 5.2 1.35 Viterbi + Reed Solomon Turbo Product Coding Eb/No (dB) Bandwidth Efficiency (bps/ Hz) 4.2 1.75 7/8 6.5 1.58 Viterbi + Reed Solomon Turbo Product Coding Turbo Less BW Turbo: Less Power
- 12. • Iterative decoding process • Process produces a likelihood and confidence level measure for each bit • Two parallel decoders “collaborate” and reach joint decision on bit value • Low latency (vs. TCC, Vit/RS) – Due to the fact that there is no need to buffer for interleaving Turbo Product Coding (TPC)
- 13. Low Density Parity Check (LDPC) • Basis of new DVB-S2 standard • Third-class of Turbo Code – Turbo Product Coding (TPC) – Turbo Convolutional Coding (TCC) • Iteratively decoded block code • Performs 0.7 dB – 1.2 dB better than TPC at low FEC rates (3/4 and below) • While coding gain is greater, processing delay can be an issue
- 14. Benefits of Forward Error Correction • Advances in FEC can offer ≥ 3 dB of performance over currently used methods • 3 dB of Coding Gain can: – Reduce bandwidth by 50% (OPEX) – Increase data throughput by a factor of 2 (OPEX) – Reduce antenna size by 30% or (CAPEX) – Reduce transmitter power by a factor of 2 (CAPEX)
- 15. TDM/MF-SCPC Model Advantage Disadvantage Dedicated bandwidth for each remote inbound Each remote requires its own space segment Provides superior Quality of Service for mission critical applications Expensive OPEX if each remote bandwidth is not fully utilized Low Latency and Low Jitter SCPC modems typically more expensive than VSAT modems Best transmission method for real-time applications, voice, data, video, broadcast, etc. Fixed data rates on the inbound links Single Channel Per Carrier
- 16. TDM/MF-TDMA Model Advantage Disadvantage Sharing of satellite bandwidth High Latency and Increased Jitter Lower overall OPEX compared to dedicated pipes Demanding remotes can burden the system Good for low data rate applications Fragmentation of packets. Less effective for voice and video Low cost remotes Expensive hub equipment Large population of users All remotes must be designed around worst case link Time Division Multiple Access
- 17. Satellite Access Technologies (“TDM”) • Hub-based shared mechanism (.. also DVB-S(2)) • “IP Packet Switching over an MCPC Carrier” • Combines multiple data streams using variable time slot lengths • Statistical multiplexing allocates bandwidth on an as- needed basis using different statistical decision criteria • Much tighter IP packet transmission than a remote shared mechanism (TDMA, DVB-RCS, etc.) • Some version of “TDM” used for the outbound carrier of most every satellite point-to-multipoint network solution
- 18. Satellite Access Technologies (TDMA) • Allows multiple remotes to access the same medium in an organized fashion • Media access control is required – Reference bursts Timing references for all stations to allow proper burst interleaving within TDMA frame – Guard time Transmit timing accuracy and range rate variation of satellite • Traffic burst – One remote at a time – Detailed traffic plan is calculated and disseminated – One or many slots per burst – One remote per slot
- 19. Satellite Access Technologies (SCPC) • Single Channel per Carrier provides the ability for one remote to access the same medium at a time in a non-contended fashion – No sharing of bandwidth between remotes within the medium itself – No concept of a timeframe as packets are tightly packed without concern of contention • No media access control is required – Associated overhead eliminated – All “bursts” are traffic, one after another not overhead • Earth station has a set amount of bandwidth available to it at all times
- 20. Satellite Access Technologies (dynamic SCPC) • dynamic SCPC links sized for remotes depending upon – SIP, H.323 or TOS byte switching – QoS rules based on address, port and/or protocol – Traffic load – Pre-determined scheduling • Single Hop Mesh – Single hop remote-to-remote links – Eliminates double-hopping – Provides single carrier operation for simultaneous connections with both hub and remote from a remote site • Remote that is allocated SCPC carrier has the entire bandwidth available to it – When SCPC carrier not needed, de-allocated • Master controller manages allocation of SCPC carriers
- 21. Satellite Access Technologies (Info Rate vs. IP Rate) • Two different data rates are important when sizing a TDMA network… IP Rate and Information Rate • IP Rate is the actual IP throughput including IP headers and data at Layer 3 of the OSI model – Represents actual LAN traffic on both remote and hub LANs • Information Rate is the actual Layer 2 information, including TDMA framing overhead, sent over the satellite – Link budgets must account for Information Rate, not IP Rate – Different TDMA platforms have different IP Rate / Information Rate ratios Depends on TDMA satellite access method – aloha, slotted aloha, deterministic, selective, etc.
- 22. Vipersat
- 23. • Combines the advantages of TDM/SCPC and TDM/TDMA – Use cost effective STDMA for low data rate inbounds – Share pools of bandwidth with other remotes, saving space segment cost – Switch inbounds to SCPC only when needed – Complete SCPC satellite network management for Vipersat components – High Bandwidth solutions – Redundancy control at Hub and Remotes – Single Hop “mesh” connectivity for remote-to-remote applications – Operates over Multiple Transponders and Satellites IP Modem Management via Vipersat STDMA Inbound TDM Broadcast SCPC Pools
- 24. Vipersat Network Products – in Action TDM dSCPC POOLS Entry Ch. CDM-570 Satellite Modem CDD-564 Quad Demodulator Vipersat Management System (VMS) Internet Hub Broadcasts Point to Multipoint carrier to all Remotes IP version of MCPC Remotes Burst back via an Entry Channel (uses TDMA technology) Remote 1 initiates a VoIP call to Remote 2 IP Router Detects this & VMS Switches TDMA to dSCPC VMS tells Rmt 1 & Hub Demod to tune to Rmt 2 dSCPC VMS tells Rmt 2 & Hub Demod to tune to Rmt 1 dSCPC Remote 1 requests more bandwidth for Video plus VoIP dSCPC Technology re-sizes all carriers PSTN
- 25. Vipersat’s STDMA • STDMA (Selective Time Division Multiple Access) – Remotes take turns bursting on a common channel. – Each modem transmits on the same frequency. – Each burst consist of a Preamble (PA), Data Slot, and Guard Band (GB). • STDMA parameters can be configured depending on the application and network: – Fixed – Dynamic Slot – Dynamic Cycle – Dynamic Cycle w/Guaranteed Information Rate – Entry Channel Mode
- 26. Dynamic SCPC (dSCPC) • SCPC links are best you can get for providing “always-on” pipes • SCPC links are typically fixed at a specific data rate, requiring manual intervention to re- size when additional applications need transport • DAMA systems provide bandwidth-on-demand for a single application; Multiple applications cannot be supported across DAMA/SCPC links without further investment in additional modem hardware • Problem – why pay for “always-on” pipes when you don’t need them 24/7? • Problem – how can you automate the bandwidth requirements of the satellite link based on the numerous daily changes in applications running over the link, and keep hardware and operational costs low? • Solution – dSCPC provides the automated mechanism to: – switch up SCPC links based on a variety of conditions: Application (H.323, SIP, ToS, QoS), Load, Schedule, VESP – alter the SCPC bandwidth to handle each application: Carrier size is dynamically increased or decreased depending on type of traffic over the link – tear down the link when the application(s) are completed Returns the remote to “home state” • Results in significant OPEX (recurring operating expense) savings
- 27. dSCPC Technology • dSCPC allows for dynamic bandwidth allocation based on several “triggers” • Pools of bandwidth are shared between remotes • In the example to the right depicting a ten remote network: – Top picture is dedicated SCPC links with TDM outbound. 8.1 MHz satellite bandwidth required for all remotes to have 512 kbps return – Bottom picture is dSCPC links with same TDM outbound; 5.94 MHz satellite bandwidth required for all remotes to have 64 kbps CIR with the ability to have 40% oversubscription. These remotes can switch up to 512 Kbps. • Savings of 2.14 MHz. At $3,000/MHz/mo: – $ 6,417 per month savings – $77,004 per year savings
- 28. Sample Savings • TDM/Fixed SCPC vs. dSCPC – Example: 20 sites requiring 1 Mbps backup Circuits Fixed SCPC requires dedicated 1 Mbps return Channels Dynamic SCPC allows for oversubscription on Inbounds (5:1 used in this example) TDM / Fixed SCPC Carriers Carrier TypeQty Bit Rate Total Code Rate Mod Bandw idth TDM Outbound TDM 1 4.0 Mbps 4.0 Mbps 3/4 QPSK 3,466,667 Hz Fixed SCPC Inbounds SCPC 20 1.0 Mbps 20.0 Mbps 3/4 QPSK 17,333,333 Hz 20,800,000 Hz $3,000 $62,400 TDM / Vipersat Dynamic SCPC Carriers Carrier TypeQty Bit Rate Total Code Rate Mod Bandw idth TDM Outbound TDM 1 4.0 Mbps 4.0 Mbps 3/4 QPSK 3,466,667 Hz STDMA Shared Channel STDMA 1 64 kbps 64 kbps 3/4 QPSK 55,467 Hz Dynamic SCPC Inbounds SCPC 4 1.0 Mbps 4.0 Mbps 3/4 QPSK 3,466,667 Hz 6,988,800 Hz $3,000 $20,966 $41,434 66.4% Total Bandw idth Required over Satellite Space Segment cost per MHz per Month Total Space Segment Cost per Month Monthly Savings (%) Total Bandw idth Required over Satellite Space Segment cost per MHz per Month Total Space Segment Cost per Month Monthly Savings ($) $497,208 Annually!!
- 29. Advanced Upstream Site Switch • Advanced Upstream Site Switch allows remotes to switch into the bandwidth pool in a mod/FEC combination other than that of its homestate • For example, remotes can switch out of homestate of QPSK, TPC ¾ to a higher order modulation, i.e. 8-QAM, 8-PSK, 16-QAM • Yields greater bandwidth efficiencies. • In the example to the right, dSCPC saves 2.1 MHz spectrum vs. TDM/SCPC links – Saves $77,004 annually • Utilizing Adv. Upstream Site Switching – Switch from QPSK to 8QAM in this example – Saves an additional 476 KHz bandwidth ($17,136/yr) – $94,140/year saved when combining both examples
- 30. Example Hub Site
- 31. Example Remote
- 32. dSCPC Upstream Switching • Applications Switching / SHOD • Protocol detection occurs at the remote • Capable of detecting the following protocols • Video - H.323, SIP, ToS • VoIP - H.323, SIP, ToS • QoS Switching • User selectable QoS rules allow switching based on: • Source and/or Destination IP Addresses • Source and/or Destination Ports • Protocol Type (RTP, HTTP, FTP, UDP, TCP, etc.) • Load Switching • Buffer status of the remote is monitored • Overloaded remotes can switch to SCPC • VESP • Vipersat External Switching Protocol • API that can be implemented in third party vendor equipment allowing requests for bandwidth by VMS • Scheduled Switching • Circuits can be switched to SCPC by using VCS • Manual Switching • Circuits can be manually switched to SCPC by VMS operator • Advanced Site Switching • Allows for switching remotes from QPSK 3/4 STDMA channel into a single alternate Modulation/FEC when going to SCPC • Policy Priority Switching • Type 254 policy is uninterruptible by other application, load, ToS, QoS or VESP switch requests. Manual and VCS can still interrupt
- 33. Vipersat Management System • Fault Management – Detects and identifies faults • Configuration Management – Parameter Settings • Accounting Management – Export usage data to billing systems • Performance Management – Status of critical parameters • Security Management – Determines network resources based on user log-in • Centralized Network Management – Manage Multiple Networks – Organize Network Layouts – Automatic Equipment Detection – Detailed Event Logs
- 34. Vipersat Management System Bandwidth Manager • Simplifies capacity management • Defines and manages space segment • Automatic upstream carrier switching • Improved network spectrum analyzer – View entire satellite – Carrier Eb/No (power) display vs. frequency Subnet Manager • Define policies for each remote upstream switch type • Limit users min/max SCPC bit rates • Specify VoIP and VTC switch rates
- 35. Single Hop On Demand TDM Outbound STDMA Return SCPC Remote 1 SCPC Remote 2
- 36. Vipersat Circuit Scheduler • Web interface SCPC scheduler • Ties into VMS database to gain knowledge of space segment • Alternative method to load or application switching • Detailed reporting information • Great for scheduling: – Video Conferences – Broadcast Events (News, Sporting) – Large File Transfers
- 37. VMS Network Deployment Manage Multiple Networks over Multiple Satellites with a Single VMS
- 40. For Official Use Only Use or disclosure of data contained on this sheet is subject to the restriction on the title page of this document. 40 Why use Carrier-in-Carrier?? • Uncovers Available BW – Specifically important within capacity constrained regions – Does NOT uncover power!! • Reduces Operating Expense (OPEX) PER BIT • Reduces Total Capital Expense (CAPEX) – Lower order Modulations and FECs require less expensive remote RF equipment • Increases Throughput • Increases Link Reliability and Security
- 41. For Official Use Only Use or disclosure of data contained on this sheet is subject to the restriction on the title page of this document. 41 Carrier-in-Carrier Overview • CnC Technology allows sharing of same satellite bandwidth by both terminals Mod_1 Demod_1 Demod_2 Mod_2 S1 S2 S1 *'+ S2 *' S1 * S2 * S1 S2 S2 S1 S1 *' + S2 *' Without Carrier-in-Carrier With Carrier-in-Carrier
- 42. DoubleTalk Carrier-in-Carrier • Based on Applied Signal Technology’s (APSG) DoubleTalk™ bandwidth compression system – Uses patented “Adaptive Cancellation” – Allows full duplex satellite links to transmit concurrently in the same segment of transponder bandwidth – Provides significant bandwidth savings • Comtech EF Data licensed the technology from APSG, and after integrating it with CDM-Qx, is offering it as DoubleTalk Carrier-in-Carrier – Delivers unprecedented operating expense savings when combined with Comtech EF Data’s advanced Forward Error Correction and Modulation techniques Without DoubleTalk Carrier-in-Carrier With DoubleTalk Carrier-in-Carrier
- 43. Carrier-in-Carrier Theory of Operation Mod_1 Demod_1 Demod_2 Mod_2 S1 S2 S1 *'+ S2 *' S1 * S2 * S1 S2 S2 S1 S1 *' + S2 *'
- 44. Eb/No Degradation - QPSK • Very low degradation when using QPSK Eb/No Degradation vs Carrier Power Ratio (QPSK) -0.5 -0.4 -0.3 -0.2 -0.1 0.0 -10 -5 0 5 10 Interferer - Desired Carrier Power (dB) Eb/NoDegradation(dB) QPSK, TPC 17/18 QPSK, TPC 3/4 QPSK, TPC 21/44 QPSK, TPC 7/8
- 45. Eb/No Degradation – 8-PSK • Low degradation except for TPC, Rate 17/18 Eb/No Degradation vs Carrier Power Ratio (8-PSK) -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 -10 -5 0 5 10 Interferer - Desired Carrier Power (dB) Eb/NoDegradation(dB) 8-PSK, TCM 2/3 8-PSK, TPC 7/8 8-PSK, TPC 3/4 8-PSK, TPC 17/18
- 46. Eb/No Degradation – 16-QAM • Low degradation for TPC, Rate 3/4 Eb/No Degradation vs Carrier Power Ratio (16-QAM) -2.0 -1.8 -1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 -10 -5 0 5 10 Interferer - Desired Carrier Power (dB) Eb/NoDegradation(dB) 16-QAM, TPC 3/4 16-QAM, TPC 7/8
- 47. How To Use Carrier-in-Carrier QPSK Change 8PSK to QPSK (Spreading). While Bandwidth increases, Power DecreasesA => B B => A Apply Carrier-in-Carrier. Composite Carrier uses Less Bandwidth & Less Power than original 8PSK link! Composite Link QPSK with Carrier-in-Carrier Original Link shown for reference A => B B => A 8PSK A => B Typical 8PSK LinkB => A
- 49. Modulation and FEC Economics Example 3.783.780.767/8TPC16QAM 1.411.411.332/3LDPC8QAM 2.931.332.931/2Vit RSQPSK Greater (MHz) PEB (MHz) Allocated (MHz) FEC Rate FEC Type Modulation Let’s look at an example of a 2.048kbps link in C-Band from a 16M to a 3.7M antenna BW Limited PEB Limited BW/PEB Balanced
- 50. Modulation and FEC Economics Example 1.411.411.332/3LDPC8QAM Outbound 7/8TPC CinC QPSK Inbound 1.78Out: 1.29 In: 0.27 Req: 1.56 Out: 1.78 In: 1.52 Req: 1.78 3/4TPC CinC QPSK Outbound Greater (MHz) PEB (MHz) Allocated (MHz) FEC Rate FEC Type Modulation Same example but now for a duplex E1 (instead of simplex E1) using CDM-QX with Carrier-in-Carrier Simplex We now look to optimize on a PAIR OF LINKS, not individual links. Duplex!! CDM-QX with CinC provides a symmetric return link for only 0.37 MHz ROI OF LESS THAN 2 MONTHS!!
- 51. For Official Use Only Use or disclosure of data contained on this sheet is subject to the restriction on the title page of this document. 51 Common Questions / Misconceptions • Misconception #1: Carrier-in-Carrier increases carrier power on the satellite so it cannot be used if original link is balanced – Truth: Proper CnC signal design specifically avoids this problem by using a less robust modulation and code rate combination, and balancing of signal powers Sum of carriers designed not to exceed satellite power allocation limits • Misconception #2: CnC increases intermodulation (IM) – Truth: CnC effectively just moves the location of the two carriers in the transponder Has no measurable effect on IM level
- 52. For Official Use Only Use or disclosure of data contained on this sheet is subject to the restriction on the title page of this document. 52 Myths/Misconceptions (cont’d) • Misconception #3: CnC Increases Latency – Truth: After initial acquisition of CnC parameters, algorithm itself has very small latency (< 1 ms) Insignificant impact on latency at any data rate • Misconception #4: Useful Only with Big-Dish-to- Big-Dish Links – Truth: Reasonable ROI for large-to-small or medium-to-medium links Typical ROIs in the 3-6 month period