Satellite Network
Dimensioning
Andreas Spoormaker
Director Customer Solutions
Engineering-Intelsat Africa
For use by Intelsat customers only – please do not distribute.
5986-Interference - 1
Agenda
• Service Level Elements
• Common Satellite Network Technology
• Economics – Cost of Ownership
• Which Solution is Best for My Network?
• Link Optimization Initiatives
For use by Intelsat customers only – please do not distribute.
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Agenda
• Service Level Elements
• Satellite Network Technology Options
• Economics - Cost of Ownership
• Which Solution is Best for My Network?
• Link Optimization Initiatives
For use by Intelsat customers only – please do not distribute.
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Service Level Elements (1)
• Example 1Mbps service descriptions…
– 1Mbps dedicated outbound / 1Mpbs dedicated inbound
– 1Mbps dedicated outbound / 256kbps dedicated inbound
– 1Mbps shared (5:1) outbound with 256kbps CIR / 256kbps shared
(5:1) inbound with 32kbps CIR
– 1Mbps shared (10:1) outbound with 128kbps CIR / 256kbps
shared (10:1) inbound with 16kbps CIR
– 1Mbps shared (25:1) outbound with no CIR / 1Mbps shared (25:1)
inbound with no CIR
• etc…
...many potential scenarios
 Need to clearly specify requirement!
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Service Level Elements (2)
IP Layer
• Common Service Level criteria at IP Layer:
– Committed Information Rate (CIR) (min/max for ACM)
– Burstable Information Rate (BIR)
– Oversubscription Ratio (X:Y)
– Quality of Service (application, VoIP, Diffserv, etc…)
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Service Level Elements (3)
IP Layer
• Network Dimensioning Considerations:
– Supported applications
– Number of users and locations
– Traffic per user/group
– Latency (terrestrial, access protocol, propagation ≈260ms,
hub processing)
– Response time
– Scope for growth/expansion of network
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Service Level Elements (4)
• Service Level criteria can only be met if following ensured:
– Latency (delay)
– Jitter (real-time packet Rx)
– BER
– Link Availability
– Downtime
…SLA’s carry underlying commercial
penalties for non-performance…
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Service Level Elements (5)
• Satellite network is one component of end to end service
• Need to dimension satellite network to ensure performance
criteria met
• Efficient delivery to remote sites
• Efficient inbound access method (to support CIR, BIR)
• Intelsat customers can deliver against SLA
(to their end customers)
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The Satellite Link
… sufficient margins must be included to
ensure link integrity …
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Necessary Inputs to Determine Proper Solution
• Satellite
• Voice Traffic
• Frequency Band
– Number of VoIP Lines
• Hub Antenna Size
– % Usage on Average
• Hub Location
– % Usage Maximum
• Remote Antenna Size
• Remote Locations
• Service Level
– Latency, Jitter, etc.
– Availability, Downtime, etc.
• Data Traffic
– CIR
– BIR
– Oversubscription Ratio
• Video Traffic
– Quality
For use by Intelsat customers only – please do not distribute.
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Agenda
• Service Level Elements
• Satellite Network Technology Options
• Economics - Cost of Ownership
• Which Solution is Best for My Network?
• Link Optimisation Initiatives
For use by Intelsat customers only – please do not distribute.
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Satellite Access Technologies
• Hub platform supporting delivery to multiple sites via shared
outbound
• Dedicated or shared inbound, depending on service
requirements/platform
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Satellite Access Technologies
Outbound (TDM, DVB-S2, etc.)
• Hub-based shared mechanism
• IP Packet Switching over an MCPC Carrier
• TDM combines multiple data streams/packets 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.) – reduced overhead
• Some version of TDM used for the outbound carrier of most
every satellite point-to-multipoint network solution
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Satellite Access Technologies
Inbound (TDMA, DVB-RCS, etc.)
• Allows multiple remotes to access shared medium in an organized
fashion
• 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
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Satellite Access Technologies
Inbound (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 access control required
– Associated overhead eliminated
– All “bursts” are traffic, one after another not overhead
• Each site has a fixed amount of bandwidth available to it at
all times
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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
critical applications
Expensive OPEX if each
remote bandwidth is not
fully utilized
Low Latency and Low
Jitter
SCPC modems typically
more expensive than
TDMA modems
Best transmission
method for real-time
applications, voice,
data, video, broadcast,
etc.
Fixed data rates on the
inbound links
Single Channel Per Carrier
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TDM/MF-TDMA Model
Advantage
Disadvantage
Sharing of satellite
bandwidth
Increased Latency and
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
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Agenda
• Service Level Elements
• Satellite Network Technology Options
• Economics - Cost of Ownership
• Which Solution is Best for My Network?
• Link Optimisation Initiatives
For use by Intelsat customers only – please do not distribute.
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Satellite Network Economics
“Cost of Ownership”
• Operating Expenses (OPEX)
– Satellite space segment
Operating
Expenses
– Teleport operations
– Licensing
• Capital Expenses (CAPEX)
Site
Rental
Operations &
Maintenance
Power
Transmission
OPEX
Spares/Support
Training
– Remote
• Indoor Kit
Capital
Expenses
• Outdoor Kit
– Hub Equipment
• Indoor Kit
Transmission
Equipment
Network
Equipment
Civil
Works
Site
Equipment
NRO
– Ground equipment, routers,
switching equipment
• Outdoor Kit
– Converters, RF, HPA,
antennas
For use by Intelsat customers only – please do not distribute.
Network Operations + Depreciation
Total Cost of Ownership
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Mbps vs. MHz
Modulation
FEC
Layer 2 O/H
Data
Mbps
• Data
• Actual Information
• Layer 2 O/H
• Control
• Addressing *
• Guard Band *
• Reference Bursts *
• FEC
• Added Redundancy
• Modulation
•Bits/Hz
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Mbps vs. MHz
Revenue and Cost Bases
Modulation
…Service REVENUE based upon
IP Rate in Mbps…
FEC
Layer 2 O/H
Data
Mbps
…Main OPEX cost based upon
total MHz required…
An end user’s service level
requirements and per-site price
points will determine what realistic
margins may be achievable…
For use by Intelsat customers only – please do not distribute.
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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 platforms have different IP Rate / Information Rate ratios
• Depends on satellite access method
– aloha, slotted aloha (minimum delay, low traffic), TDMA
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Forward Error Correction
Turbo Product Coding (TPC)
• 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
– Lower Eb/No requires less power
– Higher efficiency requires less bandwidth
Less Power
Viterbi / RS
TPC
Less
BW
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Low Density Parity Check (LDPC)
• Basis of DVB-S2 standard (LDPC/BCH)
• 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
For use by Intelsat customers only – please do not distribute.
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Spectral Efficiency vs. Eb/No
Source : Comtech EF Data
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Benefits of
Forward Error Correction
• Advances in FEC can offer ≥ 3-5 dB of performance
• 3 dB of Coding Gain can:
– Reduce required bandwidth by 50% (OPEX)
– Increase data throughput by a factor of 2 (OPEX)
– Reduce antenna size by 30% (CAPEX)
– Reduce transmitter power by a factor of 2 (CAPEX)
– Provides more link margin (Service Level)
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Bandwidth vs. Power
• Allocated BW
• Power Equivalent BW
– Transponder bandwidth
actually used
– Transponder power
required to close link
– Linear function of
modulation and FEC
– Complicated function of
hub antenna, remote
antenna and satellite
specifics along with
required Eb/No
– Decreases with higher
order mods and FECs
– “Bandwidth Limited” links
have greater allocated BW
compared to PEB
– Increases with higher order
mods and FECs
– “Power Limited” links have
greater PEB compared to
allocated BW
Balanced Allocated BW/PEB
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CAPEX (Hub Hardware)
• Two models of hub hardware cost assignment
– Per project
– Over multiple projects
• Hub platform costs can introduce significantly high barriers
to entry
– Lower cost hubs have lowered this barrier
– Virtual Network Operator (VNO) concept lowered this entry cost
• Growth costs must also be considered
– Function of how many end customers a “starter kit” can support
• Equipment re-use
– Some platforms use the same hardware for hub and remote
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CAPEX (Remote Hardware)
• Remote costs can become significant part of the total cost
of a network
– Portion of TCO grows with the size of the network
• Indoor Kit
– Low-cost TDMA/DVB-RCS Indoor Units (IDUs) have dropped in
price to $1,000
– SCPC modems $4,000+
• Outdoor Kit
– Antenna and ODU sizing based on either shared carrier size or
dedicated carrier size
– Example  1024 kbps TDMA inbound carrier with each remote
requiring a 256 kbps service
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CAPEX (Remote Hardware)
TDMA vs. SCPC
• ODU requirements  TDMA site requires ~30% more power
• Bandwidth requirements  SCPC site requires ~53% more BW
• Avg. CIR  256kbps vs. 512kbps (TDMA vs. SCPC)
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CAPEX (Remote Hardware)
TDMA vs. SCPC
• ODU requirements  TDMA site requires ~160% more power
• Bandwidth requirements  SCPC site requires ~53% more BW
• Avg. CIR  256kbps vs. 512kbps (TDMA vs. SCPC)
For use by Intelsat customers only – please do not distribute.
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CAPEX (Remote Hardware)
TDMA vs. SCPC
• ODU constant  Higher mod and/or FEC possible with SCPC
• Hub CAPEX constant in SCPC model, variable with TDMA
• Ratio of Avg. CIR / BIR will determine best solution
For use by Intelsat customers only – please do not distribute.
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Agenda
• Service Level Elements
• Satellite Network Technology Options
• Economics - Cost of Ownership
• Which Solution is Best for My Network?
• Link Optimization Initiatives
For use by Intelsat customers only – please do not distribute.
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So Which Solution is Best??
TDM / MF - SCPC
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TDM / MF-TDMA
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So Which Solution is Best??
• Satellite
• Voice Traffic
• Frequency Band
– Number of VoIP Lines
• Hub Antenna Size
– % Usage on Average
• Hub Location
– % Usage Maximum
• Remote Antenna Size
• Remote Locations
• Service Level
– Latency, Jitter
– Availability, Downtime
• Data Traffic
– CIR
– BIR
– Oversubscription Ratio
• Video Traffic
– Quality
… only with this information can
one make the proper decision…
For use by Intelsat customers only – please do not distribute.
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Agenda
• Service Level Elements
• Satellite Network Technology Options
• Economics - Cost of Ownership
• Which Solution is Best for My Network?
• Link Optimization Initiatives
For use by Intelsat customers only – please do not distribute.
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Link Performance Optimization
Intelsat support to optimise throughput / service delivery:
• Optimized link analysis (LST-5, STRIP7, IOO)
• Beam/txp/carrier allocation to optimise outbound/inbound
performance
• In-house evaluation of hardware (managed service portfolio)
 operating conditions (e.g. IESS, 16APSK DVB-S2, CCT)
• VNO – traffic optimization (iDirect)
For use by Intelsat customers only – please do not distribute.
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Network Dimensioning
Satellite Parameters
Orbit Location
Coverage
Footprint
Frequency band
Transponder Op Mode
Customer Requirements
CIR/BIR/oversubscription/QoS
VoIP traffic profiles
Video/data profile
Latency, Jitter etc.
IP/Information Rate
BER
Availability
Link Budget
Dimensioning
Satellite Bandwidth
Txp Operating Point
Hub/Remote Antenna
HPA Size
Link Performance
Network Architecture
Number of carriers
Access type (Outbound/Inbound)
Modulation, Coding
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Satellite Parameters – Footprint Data
•Technical User Guides (TUG) – Footprint Data (IS-902/62°E)
•Transponder, Connectivity, etc.
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Link Optimization
• LST5 link budget tool
• STRIP7, OFPS (Intelsat)
• 8PSK/8QAM, 16QAM, 16APSK
• ACM - maximize throughput under dynamic link conditions
(SLA)
• LDPC (incorporated into LST5)
• CCT optimization algorithm soon (guidance on interim LST-5
approach)
For use by Intelsat customers only – please do not distribute.
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16APSK Operation
• Detailed testing of Newtec Elevation DVB-S2 modulator to
determine practical operating conditions for 16APSK under
multicarrier txp / saturated txp scenarios
• With pre-correction
• No pre-correction – assessment of HPA OBO for TWTA,
linearized TWTA, SSPA
• Implications for general DVB-S2 platforms
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16APSK Operation
• No significant impact for use of linear pre-correction for group
delay/frequency response for multi-carrier transponder
• Require non-linear pre-correction to compensate for amplitude
and phase distortions associated with operation near
transponder saturation
• Uplink HPA assumed to operate multi-carrier OBO
• Requires transponder characteristics (freq response, group
delay, AM/AM, AM/PM)
• Newtec calculation of pre-distortion data (approx. 24 hours)
• Load data into Newtec modulator
For use by Intelsat customers only – please do not distribute.
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Comtech Double Talk Carrier-in-Carrier
8PSK
A => B
B => A
Typical 8PSK Link
Original Link shown
for Reference
QPSK
A => B
A => B
8PSK
QPSK (Spreading)
Bandwidth increases,
Power decreases
Composite Link
QPSK - With
DoubleTalk
Carrier-in-Carrier
For use by Intelsat customers only – please do not distribute.
Apply DoubleTalk Carrier-in-Carrier Composite Carrier uses Less Bandwidth
& Less Power Compared to Original
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Comtech Double Talk Carrier-in-Carrier
CCT Cxr
Fwd & Rtn
Teleport Loopback test
G.703 unbal
CDM-625
G.703 unbal
CDM-625
Firebird #2
CRS-280 IF Switch
Firebird #1
CRS-300 1:N
Redundancy Switch
CDM-625
“Remote”
Local NewPoint
Mgmt Router
Hub System
SpecAn
Control & Monitoring of link
test equipment
Teleport
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Thank You:
Questions?
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