satellite network dimensioning
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Satellite Network Dimensioning. Andreas Spoormaker Director Customer Solutions Engineering-Intelsat Africa. Agenda. Service Level Elements Common Satellite Network Technology Economics – Cost of Ownership Which Solution is Best for My Network? Link Optimization Initiatives. Agenda. - PowerPoint PPT PresentationTRANSCRIPT
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Satellite Network DimensioningAndreas SpoormakerDirector Customer Solutions Engineering-Intelsat Africa
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Agenda• Service Level Elements• Common Satellite Network Technology• Economics – Cost of Ownership• Which Solution is Best for My Network?• Link Optimization Initiatives
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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
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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 commercialpenalties 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
• Frequency Band
• Hub Antenna Size
• Hub Location
• Remote Antenna Size
• Remote Locations
• Service Level– Latency, Jitter, etc.
– Availability, Downtime, etc.
• Voice Traffic– Number of VoIP Lines
– % Usage on Average
– % Usage Maximum
• Data Traffic– CIR
– BIR
– Oversubscription Ratio
• Video Traffic– Quality
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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
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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 TechnologiesOutbound (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 TechnologiesInbound (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 TechnologiesInbound (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
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Satellite Network Economics“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
Operating Operating ExpensesExpenses
Capital Capital ExpensesExpenses
Network Operations + DepreciationNetwork Operations + Depreciation
Total Cost of OwnershipTotal Cost of Ownership
Operations & Maintenance
Transmission OPEX
Power
Spares/SupportTraining
SiteRental
NetworkEquipment
SiteEquipment
CivilWorks
NRO
TransmissionEquipment
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Mbps vs. MHz
DataMbps
Layer 2 O/H
FEC
Modulation • Data• Actual Information
• Layer 2 O/H• Control• Addressing * • Guard Band *• Reference Bursts *
• Modulation•Bits/Hz
• FEC• Added Redundancy
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Mbps vs. MHzRevenue and Cost Bases
DataMbps
Layer 2 O/H
FEC
Modulation …Service REVENUE based uponIP Rate in Mbps…
…Main OPEX cost based upontotal MHz required…
An end user’s service level requirements and per-site price
points will determine what realistic margins may be achievable…
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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 CorrectionTurbo 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 BW
Less Power
Viterbi / RS TPC
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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
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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
– Transponder bandwidth actually used
– Linear function of modulation and FEC
– Decreases with higher order mods and FECs
– “Bandwidth Limited” links have greater allocated BW compared to PEB
• Power Equivalent BW– 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 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)
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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
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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
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So Which Solution is Best??
TDM / MF - SCPC TDM / MF-TDMA
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So Which Solution is Best??• Satellite
• Frequency Band
• Hub Antenna Size
• Hub Location
• Remote Antenna Size
• Remote Locations
• Service Level– Latency, Jitter
– Availability, Downtime
• Voice Traffic– Number of VoIP Lines
– % Usage on Average
– % Usage Maximum
• Data Traffic– CIR
– BIR
– Oversubscription Ratio
• Video Traffic– Quality
… only with this information can one make the proper decision…
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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
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Link Performance OptimizationIntelsat 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)
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Satellite ParametersOrbit LocationCoverageFootprintFrequency bandTransponder Op Mode
Customer RequirementsCIR/BIR/oversubscription/QoSVoIP traffic profilesVideo/data profileLatency, Jitter etc.IP/Information RateBERAvailability
Network ArchitectureNumber of carriersAccess type (Outbound/Inbound)Modulation, Coding
DimensioningSatellite BandwidthTxp Operating PointHub/Remote AntennaHPA SizeLink Performance
Link Budget
Network Dimensioning
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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)
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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
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8PSK A => B B => ATypical 8PSK Link
QPSK8PSK QPSK (Spreading)
Bandwidth increases,Power decreasesA => B A => B
Original Link shownfor Reference
QPSK - WithDoubleTalk
Carrier-in-Carrier
Apply DoubleTalk Carrier-in-Carrier -Composite Carrier uses Less Bandwidth
& Less Power Compared to Original
Composite Link
Comtech Double Talk Carrier-in-Carrier
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Comtech Double Talk Carrier-in-Carrier
Teleport
“Remote”
CCT CxrFwd & Rtn
Local NewPoint
CDM-625
CDM-625
Mgmt Router
CRS-300 1:NRedundancy Switch CDM-625
SpecAn
Firebird #1
Firebird #2
G.703 unbal
G.703 unbal
Hub System
Control & Monitoring of link test equipment
CR
S-2
80 IF
Sw
itch
Teleport Loopback test
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Thank You: Questions?