Comtech - Spectral Efficiencies: Making the Most of a Limited Resource - Steve Good

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

38. DVB-S2 and Vipersat

39. Carrier-in-Carrier

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

48. Optimizing CAPEX
Remote Hardware
40W
HPA/BUC
Required
40W
HPA/BUC
Required
20W
HPA/BUC
Required
20W
HPA/BUC
Required

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