05 skyedge ii inbound overview v6.1

8/12/2019 05 SkyEdge II Inbound Overview v6.1

http://slidepdf.com/reader/full/05-skyedge-ii-inbound-overview-v61 1/44

SkyEdgeI I

Inbound Overview



2

Agenda

IB Carrier Introduction

Configuration Parameters

Carrier Types

Time Frequency Plan (TFP)

DVB-RCS BenefitsSlot Types

Capacity Requests

ICM IB Adaptivity



3

InboundDVB-RCS Introduction

SkyEdge II Inbound Channel is based in DVB-RCS (EN 301 790)

Access Scheme based on dynamic MF-TDMA Multi-Frequency Time-DivisionMultiple Access

The DVB-RCS standard defines Physical and Media Access Control (MAC)levels of the satellite segment (OSI layers 1 and 2).

Modulation and Coding

Access Scheme

Capacity Request

Burst Formats

Timing

Synchronization

Etc.



4

Inbound ChannelConfiguration Parameters

Modulation SchemesQPSK

8PSK

Coding Scheme

Turbo Code

MODCODs Available

QPSK – 1/2, 2/3, 3/4, 4/5, 6/7

8PSK – 2/3, 3/4, 4/5, 6/7

Es/No Dynamic range of 8.9 dB



5

Inbound ChannelMODCOD Es/No Threshold

Mode Code Es/No

QPSK 1/2 4.5

QPSK 2/3 5.9QPSK 3/4 6.8

QPSK 4/5 7.1

QPSK 6/7 8.2

8PSK 2/3 10.7

8PSK 3/4 11.9

8PSK 4/5 12.7

8PSK 6/7 13.4

Dynamic Range 8.9 dB



6

Inbound ChannelConfiguration Parameters

Symbol rates128, 160, 192, 256, 320, 384, 512, 640, 832, 1024,1536, 2048, 2560 Ksps.

Roll off factor

0.20

Inbound BW as low as 153.6KHz (BW = 128 Ksps x 1.20)

Frequency

BW = Sym bo l Rate x (1 + Roll off Factor)

Ampl i tude

B W



7

SEII InboundIntroduction

The IB carries all the transmissions from the VSATs including:User Traffic

Initial Logon

Capacity Requests (Allocations requests)

Maintenance Information

Offers a Reliable communication link:

The MODCODs adaptation and reservation Access mechanisms permitno error correction (no retransmissions are needed) on the IB

The IB Is composed of one or more physical channels that includes oneor more Carrier Types (CT)



8

Inbound ChannelCarrier Type CT

A Carrier Type (CT) is defined by its symbol rate and an arrangement ofslot types in a time frame

Up to four CTs can be configured per HSP

Slot Type (ST)The ST Is defined by its MODCOD and relative bandwidth inside CT

Several ST can be configures in a CT (up to 8 ST per HSP)

Each HSP has its own Time and Frequency Plan (TFP)



9

Inbound ChannelCarrier Type Example

CarrierType

SymbolRate

Amount ofChannels

MODCOD MODCODcomposition

percentage

A 128 1 QPSK 1/2 100%

B 160 1 QPSK 3/4 100%

C 256 2 QPSK 3/4 50%

8PSK 6/7 50%



10

Inbound ChannelCarrier Type Example

Freq

Time

CT- B

C T- A

CT- C

CT- C

C

QPSK ½ QPSK ½ QPSK ½QPSK ½ QPSK ½ QPSK ½

8 P S K 6 / 7

QPSK ¾

8 P

S K 6 / 7

QPSK ¾

QPSK ¾ QPSK ¾QPSK ¾ QPSK ¾ QPSK ¾ QPSK ¾QPSK ¾

C A

8 P

S K 6 / 7

8 P S K 6 / 7

QPSK ¾

QPSK ¾

8 P

S K 6 / 7

8 P S K 6 / 7

8 P

S K 6 / 7

8 P S K 6 / 7

QPSK ¾

QPSK ¾ 8 P

S K

6 / 7

8 P S K 6 / 7

8 P S K 6 / 7

8 P

S K 6 / 7

QPSK ¾

QPSK ¾



11

Inbound ChannelTime Frequency Plan (TFP)

Stop Freq

Time

Q6/7

Q 1/2 Q 1/2 Q 1/2 Q 1/2

Q6/7

Q6/7

Q3/4

Q6/7

Q6/7

Q6/7

Q3/4

Q3/4

Q 1/2 Q 1/2 Q 1/2 Q 1/2

Start Freq

The TFP specifies the layout and usage of the Inbound Carriers on aconstant period of time

TFP includes

Frequency Plan - list of Carrier’s Center frequencies and Symbol Rates

Time Plan - Carrier usage over a period of time (SuperFrame)



12

TFP is constructed to have a full repetition of a SuperFrame every 360 ms Allocation is performed every 40ms and published to all the VSATs

Each allocation round is independent. Each allocation round generates its own“allocation table” broadcasted to the network.

360 ms ecSuperFrame

CSC SYN CSC SYN CSC SYN CSC SYN

Freq

CSC SYN

TRF TRF TRF TRF TRF TRF TRF TRF

TRF TRF TRF TRF TRF TRF TRF TRF

Superframe

40 ms ec

Al locat ion Round

Time

Time Frequency Plan (TFP)Time Structure



13

Time Frequency Plan (TFP)Time Slot Types

The Time-Frequency Plan (TFP) is composed of 3 slot types:Logon Burst (CSC- Common Signaling Channel) slot

Initial Logon

Synchronization (SYNC) slot

Maintenance (Es/No report about the OB)

SAC (Satellite Access Control) field for capacity requestsTraffic (TRF) slot

User Data

SAC field (capacity request as piggybacking)

StopFreq

Time

TR F Q

6/7

TRFQ 1/2

TRFQ

6/7

TRFQ

6/7

TRFQ

3/4

TRFQ

6/7

TRFQ

6/7

TRFQ

6/7

TRFQ

3/4

TRFQ

3/4 StartFreq

C

S

S

S

S

S

S

TRFQ 1/2

TRFQ 1/2

TRFQ 1/2

TRFQ 1/2 TRFQ 1/2

TRFQ 1/2

TRFQ 1/2

TRFQ 1/2

TRFQ 1/2

C

Slots of differenttypes on the samecarrier aremultiplexed intime in each CT



14

Slot TypesCSC - Logon Burst Slot

Logon Burst (CSC) slotCarries VSAT initial network LogonIt is used in contention;

collisions may occur

The recommended default is to have one CSC per VSAT with a 10 second

interval (sizing spreadsheet)

CSC MODCODThe CSC slots are located in the most robust CT using the most robustMODCOD

If the most robust MODCOD uses 8PSK as the modulation scheme, thenthe system will define QPSK 6/7 as the MODCOD for the CSC slots



15

Slot TypesCSC - Logon Burst Slot

CSC Burst includes:Preamble for burst detection and CRCVSAT informationVSAT initial identification (VSAT ID)

VSATCapab. VSATID

Rand.VSATCapab.

Rand.VSATID

CSC Burs t (16 bytes)



16

Slot TypesSync - Maintenance Slot

Sync slots are used for:Time, frequency and power maintenanceInitial capacity requestTransfer information about the received Es/No readingsVSAT Capability

Each logged on VSAT is allocated a Sync slot per second

Sync MODCODThe Sync will be located at the most robust CT using the most robustMODCOD

If most robust MODCOD uses 8PSK as the modulation scheme, then thesystem will define QPSK 6/7 as the MODCOD for the Sync slots



17

Slot TypesSync - Maintenance Slot

SYNC burst includesPreamble for burst detectionSatellite Access Control (SAC) for capacity requests.

SYNC slot is 16 bytes



18

Slot TypesTRF - Traffic Slot

The TRF (Traffic) slot contains ATM cells that carry user data

Each Backbone packet is encapsulated over the ATM cells by AAL5 (RFC 2684)

Each TRF burst contains 1, 2 or 4 ATM cells. The default is 2.

TRF burst consists of:

Preamble for receiver detectionSAC (Satellite Access Control) field

Used for piggybacked capacity requests

2 ATM Cell

Each ATM cell carries 48 user traffic bytes (out of a total of 53 bytes)



19

618 Bytes

Data Padding Trailer

600 Bytes

618 Bytes

48 48 48

485

SA C Preamble A TM Cell A TM Cell

48


IP

ATM

TRF Slot

Backbone

AAL5



20


SAC (Satellite Access Control) = 4 Bytes

Used for piggy backed capacity requestsATM cell = 53 bytes

(incl. 5 byte header)

FEC applied and FEC bits added after scrambling

Guard

Guard

Preamble – Usedfor burst detectionand acquisition

TRF Burst

ATM Cell ATM Cell



21

Gilat SEII IBBenefits

Uses multiple MODCODS

Supports robust slot for fade mitigation

Supports more efficient slots to take advantage of better weatherconditions

Uses multiple Carrier TypesYields better satellite utilization

Eliminates the need for additional carrier



22

DVB-RCS TablesService Information (SI) Tables

SkyEdge II uses the DVB-S2 Outbound (forward link) to transmit allrelevant SI tables to define:

Satellite Position

Time-Frequency plan for Inbound channels

Frequency, power and time correctionsVSAT logon slots allocation

Individual VSAT parameters

Capacity/BW Allocation

Etc.



23

Test Your Knowledge

1. Name the slot types in the TFP___________________________________ 2. How many allocation cycles are in a SuperFrame?___________________

3. Which type slots carries capacity requests? _____________________________

4. How many CT can be configured per HSP?______________________________

5. Calculate the required channel bandwidth for a carrier with symbol rate of 512Ksps. ___________________________________________________________

6. What is the user data size in each TRF? ________________________________

7. How many MODCODs can be configured in a CT?________________________

8. What is a CSC slot? _______________________________________________

9. What is carried by the Sync slot? A._________________ B.__________________C._______________________



SkyEdgeII

Capacity Allocation Methods



25

Bandwidth Allocation Methods

BW AllocationMethods Requ es t / Pr io r i ty Uns o l ic i t ed

Rate RBDC

(Rate Based DynamicCapacity)

C2P (VoIP)

AC (Admission Control)

ABS (Absolute)

High/Medium/Low

(Flywheel included here)

Volume VBDC

(Volume BasedDynamic Capacity)

or

AVBDC

(Absolute VolumeBased DynamicCapacity)

ABS (Absolute) FCD

(Free CapacityDistribution)

High/Medium/Low



26

Rate Allocation MethodsRate Based Dynamic Capacity (RBDC)

RBDC - Rate Based Capacity RequestRate based capacity requests originated by the VSAT

Granularity of 2Kbps

A RBDC request is issued every 200 msec per priority

The VSAT refreshes AC, Abs and H, M,L requests once per second

Full multi-frequency allocation (even across different CTs)Prioritization by IB QoS mechanisms

C2P (VoIP) priority / AC (Admission Control) priority

Abs (Absolute) priority

High, Medium or Low flow priority

Used for Managed Multimedia Application (VoIP, Video), Trunk Mode (forABIS), CBR Applications and general non TCP traffic.



27

Rate Allocation MethodsRBDC Priority Levels

C2P (Connection Control Protocol)AC (Admission Control) priority

Absolute, low jitter, low delay rate based requests Guaranteed bit rateallocation (explicit grant or reject)

Minimum jitter capacity request by uniform allocations in the SuperFrame(not more than 10 ms difference)

Highest priority in the system



28

Rate Allocation MethodsRBDC Priority Levels

Abs (Absolute) PriorityGuaranteed rate based allocation requests

Priority used by the VSAT for allocation requests up to the CIR value

High, Medium and Low priorities

Weighted fair sharing rate based priority requestsNeither rate nor jitter guaranteed

Priority used by the VSAT for allocations up to the MIR value

Configurable on the DiffServ queues



29

Rate Allocation MethodsRBDC Sources Requests

Managed VoIP ApplicationsUse C2P requests

Applications included in this criteria are detected and locally managed by theVSAT application layers

Automatic SIP recognition



30


Trunk Traffic (SkyAbis Solution)Use AC RBDC allocation request

Abis traffic is dynamically measured for required satellite demand and low jitter

Trunk Mode parameter should be enabled and specific configuration is

required in the VSAT



31


CBR (Constant Bit Rate) Allocates a fixed CBR to the VSATs

Used for any application that requires strict CBR

Uses an Absolute RBDC allocation request

Must be preconfigured on the VSAT

Requested immediately after logon



32


Non TCP trafficUsed for Raw-IP and any UDP applications (TFTP, file-sharing, ICMP, etc.)

Up to CIR, use Abs RBDC allocation request

After CIR reached, use Low, Medium or High RBDC request

The HSP allocated BW according need and overall network demand

It is configurable by DiffServ VSAT queue configuration



33

Rate Allocation MethodsTraffic Sense Flywheel

Flywheel MechanismOne of the heuristics mechanism employed in SEII

It is a rate based allocation mechanism that shortens response time

The mechanism is based on the assumption that an active VSAT will soonneed to transmit more traffic even if its DRPP queues are currently empty

When any traffic that passes through the VSAT, the flywheel mechanismwill be set for three seconds (but not before the DRPP queues are empty)

The three seconds are hard coded

The flywheel request is configurable in the VSAT by 2 Kbps steps

Flywheel may be totally disabled

Flywheel uses a Low RBDC request



34

Volume Allocation MethodsVolume Based Dynamic Capacity (VBDC)

VBDC Volume Based Dynamic CapacityIt is a volume based capacity allocation dynamically requested by the VSAT

The VBDC request is issued every 100 msec for the total amount of trafficwhich accumulated since last VBDC (only the newly added traffic)

Prioritization by IB QoS mechanisms

Ab s (Abs olute) pr ior i ty

Low, Medium or High pr ior i ty

It is used for TCP type Traffic

AVBDC Absolute Volume Based Dynamic Capacity requests

This is a “health mechanism” used for recovery

This request type overwrite and replaces all previous VBDC requests

AVBDC is sent after timeout interval during which none of the VSAT’sVBDC requests were not allocated



35

Rate Allocation MethodsVBDC Sources Requests

TCP TrafficFTP, HTTP, Telnet, POP3, SMTP, etc.

Up to CIR, use Abs VBDC/ AVBDC allocation requests

After CIR is reached, use Low, Medium or High VBDC/AVBDC requests

The HSP allocated BW according need and overall network demand

It is configurable by DiffServ VSAT queue configuration



36

Free Capacity Distribution (FCD)

FCD - Free Capacity Distribution MechanismOne of the heuristics mechanism employed in SEII

It is a unsolicited volume based capacity allocation that assigns theunused capacity

The mechanism is based on the assumption that some unused capacitycan remain after all pending capacity requests have been processed

Allocated by the HSP without any request or signaling from the VSATs

The HSP allocates a configurable number of slots equally to each VSATs in“round robin” manner

The Free Capacity is distributed equally by the Hub to:

All on-line VSATsor

All idle VSATs



Inbound Adaptivity



38

ICM – 3 Dimensions of AdaptivityMultiple Dimensions of IB Adaptivity

Adaptive channel rate selection (ICM 1D)Each VSAT is allocated the appropriate symbol rate

Adaptive MODCOD selection (ICM 2D)

Each VSAT is allocated the best possible MODCOD from the plan

Adaptive Uplink Power Control (ICM 3D)

The BUC output power is increased or decreased based on the receivedsignal



39

Multi-Channel Selection

Q ¾ Q ¾ Q ¾ Q ¾ Q ¾ Q ¾ Q ¾ Q ¾

Q ¾ Q ¾ Q ¾ Q ¾ Q ¾ Q ¾ Q ¾ Q ¾

Q ¾ Q ¾ Q ¾ Q ¾ Q ¾ Q ¾ Q ¾ Q ¾

Freq

Time

Q ¾ Q ¾

256ks/s

128ks/sQ ¾ Q ¾ Q ¾ Q ¾

Multi-Channel selection permits the adaptation of Symbol ratesAll carriers have their own symbol rateKnown also as ICM (IB Coding Modulation) 1D



40

MODCOD Allocation

TRF are allocated on a more robust or more efficient MODCOD withinsame or even different channels of different Symbol RatesSymbol rate and MODCOD division optimized per network:

Different coverage areasDifferent VSAT capabilities / throughput requirements

Known also as ICM (IB Coding Modulation) 2D

Q ¾Q ¾Q ¾Q ¾Q ¾Q ¾Q ¾Q ¾

Q ¾Q ¾Q ¾Q ¾Q ¾Q ¾Q ¾Q ¾

Q ¾Q ¾Q ¾Q ¾Q ¾Q ¾Q ¾Q ¾

Freq

Time

Q ½Q ½

256ks/s

256ks/sQ ½Q ½ Q ½Q ½

8¾

8¾

86 /7

8¾

8¾

86 /7

8¾

8¾

86 /7

8¾

8¾ 256ks/s

1.1dB 4.3dB 1.3dBGain per change



41

Power Loop

Also known as Power Adaptive Coding Modulation (P-ACM) or Known alsoas ICM (IB Coding Modulation) 3D

Remote Unit includes Linear BUC with adaptive power control

The VSAT can increase TX power as the link faces fade conditions

The VSAT determines its 1dB compression point and adapts TX power tochanging link conditions so that transmissions are received at a fixed level atthe satellite

When weather conditions worsen the VSAT first increases TX power untilreaches its limit, then robust MODCODs are used

Received E S /N 0(in OB to VSAT)

SYNC bursts(every second)

Decision toincrease/decrease



42

Power Loop

The Power loop compensates for:Rain fade

Static attenuation (such as cable)

Satellite location offset and aging

Temperature and frequency effects on BUC gain

The BUC Saturation point is discovered by the Power Loop mechanism onceper hour

The VSAT increases SYNC bursts TX power and receives SYNC receptionpower readings from the hub until saturation is reached

Saturation: TX power increase doesn’t fully translate into Rx power increase

The Power loop is maintain used the Sync slots every second

During the Power loop process, TRF Transmission power is not affected



43

Test Your Knowledge

1. Which allocation mechanism is guaranteed?____________________________

2. Describe two differences between Volume based and Rate Based CapacityRequests

__________________________________________________________________ __________________________________________________________________

3. Describe the Flywheel mechanism ____________________________________

4. What is AVBDC requests used for?____________________________________

5. How does the VSAT learn the Saturation point of the BUC? __________________________________________________________________

6. Can the same VSAT be allocated on a efficient or robust MODCODs indifferent CT?

__________________________________________________________________



The En d

05 skyedge ii inbound overview v6.1

Documents