solutions for satellite ip data transmission

Created on 12/12/2006 18:24:00 Issue 56 www.satcom-services.com

Solutions for Satellite IP Data Transmission

1.0 Overview Advantech, with many years of experience in providing IP (Internet Protocol) connectivity via satellite systems, offers solutions tailored for many different applications. Advantech’s solutions have been designed to support networks scaling from single point-to-point links up to networks requiring 10,000+ users. More significantly, we have many customers using these systems every day, carrying data vital to their business. Our systems start from simple IP Bridges, that can be optionally fitted to all of our standard SCPC products, progress to satellite networking products, including DVB-S2, DVB-SCPC and DVB-RCS solutions culminating to IP networks for thousands of users and dedicated high speed >100Mbps point-to-point IP data links. 2.0 Applications

As many communication applications begin to use it as a basis, IP support is becoming increasingly important to the world of satellite communications. For example:

• IP multicasting • Fast Internet access, e.g. Internet cafe • Voice over IP telephony (typically as part of an Internet access package) • Proxy server synchronization • Streaming Audio/Video • Business TV, Training, Live Events • Push: Stock Market, News Feed and Database • VPN with centralised databases

There are many markets in need of such solutions yet in our experience, the most common are:

• Extending corporate network access to remote sites. • Internet provision to remote sites. • Defence applications (e.g. Internet café for troops). • Multimedia broadcast and contribution links.


Satellite communications equipment is now completely network-aware and provides a full network stack above the transmission layer. Advantech has acknowledged this and offers diverse network capabilities in its product portfolio. An IP-based satellite network can be seen as an IP network cloud. In a typical star configuration, the network consists of access terminals and a satellite gateway or hub. The IP capabilities of the satellite modem can vary depending on the site requirements. For access terminals, the set of IP features offered by Advantech include:

• DHCP • NAT/PAT • VLAN

In addition to these standard access features, Advantech IP networks offer industry-leading capabilities including:

• TCP and HTTP Acceleration • Level 3 QoS • Encryption • Firewall/Packet Filtering • Static and Dynamic Routing • AAA (Authentication, Authorization and Accounting) • IP Services including DNS and FTP/TFTP

Advantech IP products are entirely SNMP manageable and offer additional configuration interfaces including CISCOTM-like command line interfaces and HTTP graphical management. The complete list of IP features are described in the IP Gateway data sheet, which is available from the by contacting us: [email protected] Advantech satellite IP networks can be classified in three families: • DVB-based two-way satellite networks (with SCPC or RCS return links)

[Section Error! Reference source not found.3.0] • SCPC Star networks [Section 4.0] • High speed backbone / high speed distribution links [Section 6.0]


The selection of one of these networks is based on service-provider requirements including the IP services, network size and integration with existing networks. The selection criteria are described in more detail in Section 5.0. DVB-based two-way satellite networks (SatNet) support a service-provider’s network requirements at all stages of network deployment, offering low initial investment that subsequently grows in-line with network expansion. Starting from small-scale SCPC networks, the network evolves to a DVB-RCS MF-TDMA network. The key aspect of this approach, known as SatNet Pay-as-You-GrowTM, is the re-use of user terminal equipment in both SCPC and RCS. This offers the service-provider major cost savings as their network size grows. The DVB-SCPC and DVB-RCS SatNet solutions rely on the DVB standards on both the forward and return links and offers an integration path with existing service-provider infrastructure. The SCPC Star network solutions are based on the AMT60 product and offer increased bandwidth efficiency through the use of HDLC framing on the satellite link. Well-suited to dedicated high quality links that require fixed bandwidth, the SCPC Star network can also operate with a star topology DVB forward link for integration in existing MPEG multiplexers.


3.0 Advantech SatNet Solutions (DVB-SCPC & DVB-RCS) Advantech offers the most scalable solutions of the industry available at the most competitive cost. The SatNet Pay-as-You-Grow™ approach supports the service provider's requirements at all stages of a network deployment. Starting from an SCPC-based network, our strategy enables the network operator and service provider to migrate to DVB-RCS while re-using the same user terminal equipment and forward link equipment. This allows to easily grow the system from a few SCPC terminals to hundreds of DVB-RCS terminals. Further, the Pay-as-You-Grow™ strategy makes it possible to scale up the DVB-RCS hub from hundreds of terminals to tens of thousands of terminals.

3.1. DVB-SCPC The DVB-SCPC SatNet solution combines a high rate forward link with a set of discrete return link carriers providing dedicated bandwidth to each of the user terminals. DVB-SCPC networks offer the advantages of being easily installed


and have lower operational costs, particularly at initial network deployment. The hard committed bandwidth of SCPC is also attractive to many users of SCPC networks. The DVB-SCPC network architecture is shown in below:

Customer LAN

Customer LAN

OptionalRouter

S5400

S5400

HUB TERMINALS

AMT-70IP Encapsulator

1:N Splitter

RS CS TR RD TD CDTALK / DATA

TALK

RS CS TR RD TD CDTALK / DATA

TALK

AMT-34

AMT-34

Figure 1: DVB-SCPC Network Architecture

Forward Link

The forward link is based on the DVB-S/S2 standard (EN 300 421/ EN 302 307) used for digital video broadcasting. The forward link carrier rate can vary from 1-45MBaud with data rates of up to 80Mbps (limited by terminal throughput). The forward link uses Multi-Protocol Encapsulation (MPE) of IP data into MPEG frames. An Advantech encapsulator is used in the Gateway for data encapsulation; however, this architecture is suited to introduction of 3rd party encapsulators.

Return Link

The return link is an MPEG-based SCPC carrier that utilizes the coding available in DVB-RCS. To maximize return link bandwidth efficiency, section packing is used in conjunction with MPE. The return link supports both QPSK and 8PSK modulation.


DVB-SCPC Micro Hub

The DVB-SCPC Micro Hub is an IF (L-band or 70/140 MHz) - Ethernet integrated modem-router equipment chain that provides access to the terrestrial network. The hub consists of a single broadcast forward transmit chain in conjunction with return links comprising of banks of SCPC receivers. Both the broadcast forward link and SCPC return receivers have Ethernet interfaces and therefore can be configured to suit the network infrastructure of the hub. All that is required is to close the IP loop in the regular switch/hub device.

AMT34: 4-Channel SCPC Integrated Receiver Router

The AMT34 can be configured as a quad receiver for the scalable architecture. When configured for this architecture, the AMT34 includes the IP Gateway, MPEG to IP de-capsulation and offers a native 10/100BT Ethernet interface. The AMT34 can be easily integrated into the gateway IP infrastructure as required by the end-customer.

IP Encapsulator

The SCPC Encapsulator is an Ethernet to ASI IP Encapsulator. This encapsulator performs standard MPE encapsulation of IP and interfaces to the modulator via ASI. Advantech provides an extremely cost-effective IPE solution for this application. Additionally, 3rd party encapsulators may also be used for meeting specific customer requirements.

AMT70 Modulator

The AMT70/75 DVB-S/S2 modulator is configured with an ASI interface for connection to the IP Encapsulator.

3.2. DVB-RCS

In its standard form, a DVB-RCS network is a star-based VSAT network providing access to the Internet and related networks. Advantech offers a compact RCS system that supports up to thousands of user terminals, and beyond, in this architecture. In addition, the capabilities of this network go beyond standard RCS to offer 8PSK return links and mesh capabilities, DVB-S2 ACM, as well as dual SCPC/RCS return link capabilities.


Forward Link

The forward link is based on the DVB-S/S2 standard (EN 300 421/ EN 302 307) used for digital video broadcasting. The forward link carrier rate can vary from 1-45MBaud (DVB-S) with data rates of up to 80Mbps. The forward link uses Multi-Protocol Encapsulation (MPE) of IP data into MPEG frames. As with the DVB-SCPC network, an Advantech-provided encapsulator is available and the architecture supports 3rd party encapsulators.

Return Link

The return link is Multi-Frequency TDMA. Each TDMA carrier can range from 64kbps to 8Mbps. The terminal is capable of frequency hopping among the return link carriers to ensure maximum use of return link bandwidth. A hub-based scheduler provides dynamic bandwidth control. The transmission by terminals on the return link is controlled via the hub – only logon burst use random access. Individual terminals can be assigned constant bandwidth or the terminal can make dynamic bandwidth requests. These two mechanisms can be combined to guarantee each terminal a minimum bandwidth while allowing access to a complete return link carrier bandwidth for short periods. The inbound return links support concatenated RS/Convolutional or Turbo Convolutional encoding, using QPSK modulation and with an option for 8PSK available. Return link bandwidth is assigned to user terminals in a Burst Time Plan. The bandwidth scheduling algorithms support Committed Information Rate (CIR) and dynamic packet-by-packet bandwidth requests. This provides an exceedingly flexible mechanism for scheduling individual terminals in regards to Service Layer Agreements (SLAs). DVB-RCS Micro, Mini & Max Hubs The DVB-RCS Hub product portfolio consists of equipment-scalable rack units that operate both as a DVB-RCS modem and as a network manager providing access to the DVB-RCS network. The product line consists of the Micro, Mini and Max hubs, capable of supporting networks as small as 20 terminals and as large as 10,000 terminals, and beyond.


Network ManagerRouter

Encapsulator

AMT-70 Modulatorwith NCR

Burst Demodulator

ASI Ethernet

TrafficEthernet

ManagementEthernet

10MHz1pps

Figure 2: DVB-RCS Hub Schematic

AMT70 Modulator

The hub uses the Advantech AMT70 Universal Modem. The AMT70 supports a broad range of transmission standards including both DVB-S and DVB-S2. As part of RCS network synchronization, the AMT70 supports NCR time stamping and synchronization via 10MHz and GPS’ 1pps inputs. The AMT70 supports the full range of DVB-S/S2 coding and modulation.

Burst Demodulator

The hub burst demodulator is a full IF to baseband multi-carrier demodulator (MCD). Packaged as a single rack-mount unit, the MCD supports an L-band interface, performs frequency de-multiplexing, burst demodulation and decoding and IP reassembly. Features of the MCD include: • L-band interface (950 to 2150 MHz). • Maximum Throughput: 24Mbps • Maximum Bandwidth: 34MHz • Supported Traffic Encapsulation Format: 1 & 2 ATM and MPEG


• Symbol Rate: Selectable per carrier • Burst Format: Selectable per carrier • Maximum number of carriers per MCD: 96 • Carrier rates: 64kbps to 8Mbps • Channel spacing: 1.25 to 1.50 (variable) • QPSK and 8PSK demodulation. • Timing, Power and Frequency Measurements on a burst-by-burst basis. • Turbo or RS-V FEC decoder. • 10MHz/1pps synchronization including NCR loading.

Network Manager/Router/Encapsulator

The main features are: • Network Manager

♦ Network entry and exit control ♦ Return link bandwidth scheduling ♦ Configuring the return link ♦ Monitoring the performance of terminals on the return link ♦ Monitoring overall network performance

• Router

♦ Forwarding of IP traffic between the satellite and terrestrial networks ♦ IP-Layer traffic shaping (using an optional traffic shaper) ♦ Level 3 QoS ♦ Terrestrial Routing Protocols

• Encapsulator

♦ MPE encapsulation of user IP traffic ♦ Insertion of RCS tables ♦ Support for 3rd Party encapsulators

3.3. DVB-SCPC/RCS Terminals

Advantech offers a portfolio of terminal products for the DVB-based two-way SatNet solutions. These terminals are built on field-proven DVB-RCS technology that has been deployed worldwide. Advantech Satnet terminals are DVB-RCS standard compliant and offer additional value-added features that enable the service-provider to increase their return on investment. Key features of the terminal portfolio include:

• Full-featured IP networking including QoS


• DVB-S and S2 Forward Links • SCPC and DVB-RCS Return Links • High Forward Link Throughput (36Mbps sustained) • High Return Link Throughput (up to 8Mbps) • Higher Order Return Link Modulation (8PSK) • Local and remote management via SNMP, HTTP and Command Line

Interface • Installation support including scripts and antenna alignment tools • Reliable remote software upgrade • Flexible multicasting • Industry standard BUC/LNB Interface with 2-cable IFL

The Advantech SatNet terminal portfolio consists an Indoor Unit (IDU) and Outdoor Unit (ODU). Two product lines are available: the affordable Series 4000 (with Model S4100) and the enterprise-oriented Series 5000 (with Models S5100/5200/5300/5400). Both product lines support DVB-S and DVB-S2. The Series 5000 supports as well Mesh connectivity, DVB-S2 ACM mode, and SCPC transmission mode (for DVB-SCPC satellite networks). There is also a receive-only terminal (ROT) supporting both DVB-S and DVB-S2 called based on the Model S1010 IDU.

Figure 2: DVB-RCS Terminal Schematic


4.0 SCPC Star Network Solutions (AMT60/65) The AMT60/65 system provides an SCPC network combining a high rate forward link with a set of discrete return link carriers providing dedicated bandwidth to each of the user terminals. SCPC Networks offer the advantages of being easily installed and have lower operational costs, particularly at initial network deployment. The hard committed bandwidth of SCPC is also attractive to many users of SCPC networks. The AMT60 system can be scaled from QPSK to 16-ary constellations on both forward and return link while the return link can support up to 10Mbps sustained throughput. In addition, AMT60 systems can operate as either MPEG-TS MPE encapsulation, or HDLC (Frame Relay), consequently further improving spectrum efficiency. The SCPC network architecture is shown below:

Router

HUB

Frame Relay System

Forward Link

AMT-70 U/C PA

Return Link

LNBD/CAMT34IP G/W

Terminal

AMT61

RFFE

Terminal

AMT61

RFFE

Terminal

AMT61

RFFETerminal

AMT61

RFFE

Figure 3: Frame Relay based AMT60 series Solution


4.1 Hub System

The hub for this system does not require an MPEG Encapsulation unit. This saves both money and link capacity, as MPEG Encapsulation typically adds approximately 16% to 20% overhead on top of the data. This function is replaced by HDLC (Frame Relay) encapsulation inside the AMT70 Modulator. The Modulator is equipped with a high speed (full 10/100 Base-T) IP Gateway card and the HDLC encapsulation is implemented on this card. The Modulator can transmit any of the supported AMT70 series modulation / coding systems (Intelsat / DVB-S / DVB-DSNG / Turbo (eTPC) or DVB-S2 LDPC/BCH). This would allow a Turbo 16QAM or 16APSK DVB-S2 forward link. The DVB-S2 forward link operates in Generic stream mode, which treats the forward link as a pure serial data stream. The return path reception in the hub is very similar to the DVB-SCPC and DVB-RCS satellite networking systems. It is implemented using AMT34 Quad Demodulator units including the IP Gateway card. However, in this system there is no need for an MPEG De-capsulation function in the return path. This function is replaced by an HDLC De-framer. Each of the Quad units has only one 10/100 Base-T output and aggregates the received data from 4 different remote terminals into one IP data flow. Note that it is possible to construct VLANs within the AMT60 system allowing different IP networks to use the common transmission network without compromising each users network security.

4.2 AMT60/65 Series Terminal products

The AMT60 series supports a number of different terminals. The AMT60 is a receive-only high-end IDR solution for users who utilize an alternative return path technology. The receiver can support DVB-S / DVB-DSNG (8PSK/16QAM) / Intelsat and Turbo (QPSK/8PSK and 16QAM) modes and can operate from 64kbps/S up to >100 Mbps/S. The AMT61 sister product provides both receive and transmit functionality. The receiver is identical to the AMT60 and the transmitter is based on Advantech’s AMT30 series product and provides QPSK/8PSK/16QAM modulation with Intelsat and Turbo encoding. The AMT65 is similar to the AMT61 but offers DVB-S2 receive functionality. All these products are 1RU 19inch Rack Mount units with a built-in IP Gateway and HDLC encapsulation / de-capsulation.


Figure 4: AMT61/65 Terminal Architecture

This architecture enables very powerful high-speed IP terminals with guaranteed latency and throughput.

IP

Gateway

10/100 Base-T

Demodulator DVB-S/ DSNG/ S2/ Turbo

AMT30 Modulator

L Band

AMT61 Integrated Terminal (1RU 19inch Rack)


4.3 AMT60/65 Forward link example with MPEG

Router

HUB

Forward Link

MPE AMT-70 U/C PA

Return Link

LNBD/CAMT34IP G/W

Terminal

AMT61

RFFE

Terminal

AMT61

RFFE

Terminal

AMT61

RFFETerminal

AMT61

RFFE

Figure 5: AMT60 series with MPEG Framing

It is also possible to use the AMT60 series in a system with MPEG encapsulation. The Hub for this system will be identical to the DVB-SCPC SatNet system. It requires an MPEG Encapsulator and the AMT34 units incorporate


MPEG de-capsulation. The terminals also implement MPEG Encapsulation / De-capsulation in their IP Gateway cards. This system could find application in a Hybrid network which shared a common DVB forward link but the terminals could either be DVB-RCS for lower bandwidth TDMA users or AMT61 for users who required an SCPC return link with its guaranteed bandwidth and latency.


5.0 IP Network Selection

The selection between a DVB-SCPC networkand an AMT60 network is based on the services and the network size. This section focuses on the return link element of these systems as the differentiator. In terms of forward link, both systems support DVB-based links and can be integrated with existing infrastructure – the AMT60 also offers Frame Relay/HDLC framing that has reduced overhead when compared to DVB-MPE and support for 16QAM / 16APSK forward links. The IP features are common between the two network types. Both DVB-SCPC and AMT60 operate in SCPC mode, providing dedicated bandwidth to end customers. SCPC is well suited to applications where the customer has a continuous bandwidth requirement or when a customer needs guaranteed access to a fixed amount of bandwidth. A service-provider who has these requirements with no plans to evolve the services can choose either DVB-SCPC or AMT60/65 based networks. On the other hand, the AMT60/65 offers the advantage of higher data rates (>110Mbps), lower bandwidth overhead with HDLC framing and higher order modulation schemes in both directions. Both DVB-SCPC and AMT60 solutions can be integrated with existing DVB-based forward links. Service-providers who foresee a migration to MF-TDMA can start with the DVB- SCPC solution and change to MF-TDMA when appropriate. The MF-TDMA DVB-RCS network can be operated in both contention-less and contention-based modes depending on how the service-provider configures the return link scheduler. As compared to SCPC services, which scale with number of users, the RCS hub infrastructure costs scales with either users or bandwidth. This means that for services that rely on statistical multiplexing, the infrastructure costs will be lower as the bandwidth is shared. The contention-less mode of operation, implemented through providing committed information rates, can offer reduced infrastructure and bandwidth costs as the service-provider network grows. Contention-based services are well suited to burst traffic requirements, which are typically related to HTTP and Internet access. In addition to the trade-offs that can be made based on these considerations, it is also possible to offer hybrid networks, simultaneously consisting of both SCPC and DVB-RCS links in order to optimise the offering of the service-provider.


6.0 High Speed Back-bone / Distribution Solutions

The AMT75 product range offers high-end IP Back-bone and IP distribution solutions. The range is outlined in Error! Reference source not found.. AMT75 is a wide-ranging (from 128kbps to 150Mbps) DVB-S2 QPSK, 8PSK, 16APSK and 32APSK product. It also supports multi-stream Variable Coding Modulation (VCM) and Adaptive Coding Modulation (ACM) operating modes.

Table 1: AMT75 Configurations

Model ASI 10/100 Base-T Ethernet

Octal G703 & 10/100 Base-T

AMT75 Modulator √ √ √

AMT75 Modem √ √ √

AMT75R Receiver only

√ √ X

AMT75R Dual Receiver

√ √ X

The AMT75 can be configured to distribute IP from an AMT75 TX only modulator to multiple AMT75R receivers. Both the modulator and receiver have the IP encapsulation and de-capsulation functions integrated into the units along with full router capabilities. The system can be configured to have routing or just to be an Ethernet bridge. The in-built router can process up to 35,000 packets per second allowing up to 92Mbps of large packet IP to be transmitted over the satellite link. Alternatively 2 or more AMT75 can be deployed in point-to-point IP backbone applications for IP trunking applications. Applications for AMT75 include high speed > 50Mbps IP distribution to multiple receive sites, such as distributing IP TV to multiple triple-play head-ends. The IP backbone applications include IP backbone disaster recovery restoration, backbone solutions where fibre is not present and IP broadcasting of H.264 video.


7.0 Glossary of Terms

Table 2: Glossary

DVB Digital Video Broadcast, the Project defining transmission standards

DVB-DSNG Digital Video Broadcast, Digital Satellite News Gathering

DVB-MPE Digital Video Broadcast, Multi-Protocol Encapsulation

DVB-RCS Digital Video Broadcast, Return Channel over Satellite

DVB-S Digital Video Broadcast, Satellite

DVB-S2 Digital Video Broadcast, Satellite – Version 2

HBD Hub Burst Demodulator

HDLC High-level Data Link Control

IP Internet Protocol

MF-TDMA Multi Frequency – Time Division Multiple Access

MPEG Moving Picture Experts Group, authors of encapsulation standards for multimedia data

SCPC Single Channel Per Carrier

Joyce Taddeo

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solutions for satellite ip data transmission

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