1. Advanced VSAT Overview:
The Advanced VSAT CDM-800 Series modems (CTOG-250, CDM-800, CDD-880 & CDM-840) integrate modem/router technology that provides a unique topology that is designated by the type of hardware. The hardware determines the placement location, Hub or Remote to build a Point-to-Multipoint network. The physical layer utilizes DVB-S2, SCPC, and IP circuit switched management, offering flexibility, optimization and control of private satellite networks. The 800 series is designed to connect low to ultra high-speed data link connections between Ethernet LAN to satellite WAN networks, providing a variety of communications services to Operators, Service Providers, and Enterprise Users. The benefit of this architecture yields seamless bandwidth management on-demand, while simplifying network capacity needs.
The Comtech Vipersat network solution integrates this advanced modem/router with the powerful network management tool, the Vipersat Management System (VMS). The VMS provides for traditional monitor and control of the 800 series modem, but more than just an M&C package, the VMS offers unique bandwidth management that is ideal for IP-switched networks. An entries channel provides a method for tens of hundreds on remotes to initialize and gain access to the network using a slotted aloha channel. Upon initial configuration or boot the remotes receive assigned transmit information to announce, register and automatically switched to assigned dSCPC bandwidth.
Main characteristics:
· Up to 160 Mbps / 62 Msps
· QPSK, 8PSK, 16APSK and 32APSK
· Adaptive Coding & Modulation (ACM)
· Variable Coding & Modulation (VCM)
· Normal Frame, Short Frame
· Advanced Quality of Service (QoS)
· Group QoS
· DiffServ
· Rule-based – CIR/MIR, Priority/MIR
· Header compression
· Lossless payload compression
· Low overhead Enhanced Generic Stream Encapsulation
· VersaFEC low latency LDPC Return (Patented)
· Up to 15.35 Mbps / 4.5 Msps
· Adaptive Coding & Modulation (ACM)
· Constant Coding & Modulation (CCM)
· Rule-based – CIR/MIR, Priority/MIR
· Header compression
· Lossless payload compression
· Ultra low overhead Streamline Encapsulation (SLE) (Patent Pending)
· Dynamic bandwidth management
· Share pools of bandwidth with other terminals
· Bandwidth can be increased or decreased on demand
· Lossless switching
The CDM-800 statistical multiplexing benefit of a shared outbound carrier from a single point to a multiple remote terminals provides significant bandwidth and equipment savings.
• Full statistical multiplexing of the Point to Multi-Point shared outbound
• Per Remote Es/No reporting and MODCOD assignment
• Group QoS
– Each Group contains the matching Remotes
– “VCM Only MODCOD” specifies the MODCOD when the Remotes cannot be discovered
• CTOG Specifications
– Supports 256 QoS Groups
– 32 QoS rules per Group
– 128 Subnets per Group
– 2000 Total Routes
Variable Coding and Modulation (VCM)
With the introduction of Variable Coding and Modulation (VCM) through group QoS, the carrier can be configured so sites on the fringe of the satellite’s footprint (lowest EIRP) can be configured with lower order MODCOD, while sites in the center of the beam (higher EIRP), can be configured with higher order MODCOD while operating simultaneously in the same carrier. A typical satellite footprint is shown below with the EIRP contours shown.
Adaptive Coding & Modulation (ACM)
ACM is a technique that allows for automatic change in modulation and code rate in response to changing link conditions
– Converts link margin into increased capacity – average throughput gain of 100% (or more) is possible, compared to traditional CCM
Most of the year, the link operates at significantly increased throughput
For the worst few hours of the year, the link may be available with lower throughput
– Optimizes channel coding and modulation on a frame-by-frame basis
– Allows each remote to operate optimally subject to antenna size, location within the footprint, rain fade and other impairments
ACM can maximize throughput under all conditions
– Rain fade
– Inclined orbit satellite operation
– Antenna pointing error
– System Noise
– Interference
– Other impairments
2. Vipersat Management System (VMS) :
The Vipersat Management System (VMS) is primarily a bandwidth manager the key feature of which is to manage dSCPC carriers. It is designed to work in any satellite environment. As long as the operator configuring the RF Manager has access to a few system parameters, VMS will perform all calculations required to manage the bandwidth in predefined pools. If the operator had to perform all the calculations there would be a much greater risk of error. This document covers the features of the RF chain in the VMS and provides an overview of the issues involved in setting up a satellite network.
VMS is a feature-rich, capacity and network management system with an intuitive, user-friendly GUI and a high degree of configuration automation. VMS is designed to enable network administrators and satellite service providers to easily configure their networks and rapidly and effectively respond to network anomalies. Much more than just a network monitor and control platform, VMS automates the carrier switching and spectrum management processes within the satellite network. These capabilities allow SCPC carriers to be resized automatically based on a variety of user-defined policies, providing on demand services and unparalleled space segment savings.
For the mobility market, the VMS topology display of the managed system has been enhanced with a 3D globe view of the network, Figure 1. Globe view displays the real-time status and operation of the network dynamically. Satellite terminals are automatically populated onto the global network and their location, heading, and actual movements are dynamically tracked and displayed on the globe map. The globe map display size, terminal location, rotation, and lighting source are customizable by the operator.
Some customers may not want the location of their remote sites to be transmitted over the network. For this reason we have made it an optional feature, so that location information can be suppressed.
Key features of the VMS include:
· Centralized network and capacity management
· Dynamic SCPC (dSCPC) carrier allocation and true bandwidth on-demand capability
· Automation of space segment capacity efficiencies
· User-defined policies for upstream carrier switching
· Redundancy configurations for hub and remote hardware
· Use of higher order modulation and Forward Error Correction (FEC) techniques
· Site distribution list in multi-point automatic policy-based switching for IP multicast
· Switching protocol enabling external messaging to switch carriers to multi-point destinations
· Operates over multiple transponders and satellites
· Scalable from small to large networks
· Auto detection of new nodes
· Detailed event logs able to be filtered and exported
· Ability to generate SNMP traps can be forwarded to hierarchal NMS management platforms
· Complete IP based digital services over satellite
Virtually all information about the carrier is available from the Bandwidth View.
The key feature in Vipersat is the ability to dynamically manage bandwidth. There is no other product on the market that can provide the capability to automatically resize carriers, prioritize sites and applications, allow for bandwidth guarantees and has the built in recovery mechanisms to insure the maximum level of efficiency in the use of satellite space segment.
· ECM Switching
· Load Switching
· ToS switching
· Legacy Applications Switching
· Manual Switching
The switching engine is a core component of the Switching Subsystem in the VMS responsible for accepting data-rate change requests for a modulator, determining resource availability and coordinating the reconfiguration of devices to fulfill those requests.
The engine interacts with its environment through a set of internal interfaces. This allows the engine to work with different types of carriers (in-band and out-of-band), and hardware devices (all devices that VMS currently has M&C support for) without specific knowledge of those components.
The engine depends on other components of the system in order to fulfill its role. It depends on device drivers to provide information about limits to perform operations based on device specifications (i.e. calculating bandwidth or power required given a set of transmission parameters). It depends on the bandwidth manager (RF manager) to perform frequency calculations and track device visibility. It also depends on switching state objects to interface with external clients, and translate results of solutions into switch type specific command structures for the modem drivers to use for sending commands to the actual hardware.
The allocation space is the component that manages the switching functionality for a particular satellite. It maintains the satellites available resources. It tracks allocations and pre-allocations. It hosts all the queuing functionality and it is also the entry point for switch requests to be processed by the engine. Each allocation space executes operations in parallel (assuming available processing resources).
Vipersat is the industry standard for SCPC bandwidth-on-demand solutions. Enhancing its innovative dSCPC (dynamic SCPC) algorithm to support bandwidth guarantees and site priorities is unparalleled in the industry today.
With dSCPC, when a remote site modem detects a previously configured application, such as a VoIP call, video conference, or QOS stamped traffic, the modem requests inbound (remote to hub) bandwidth from the Vipersat Management Server (VMS). The VMS then allocates inbound bandwidth for the site, and reconfigures modem(s) and demodulators(s) to support the request.
3. Hub Overview:
4. Remote Overview:
The CDM-840 Remote Router is an integral component of Comtech EF Data’s Advanced VSAT Series product offering. This point-to-multipoint IP Remote Router has been developed as the “spoke” or remote site equipment in hub-and-spoke network topologies that require high quality “always-on” availability.
Featuring one 10/100/1000 Gigabit Ethernet (GigE) interface, one 10/100 Fast Ethernet (FE) interface, and providing industry-leading WAN bandwidth optimization, the CDM-840 is designed to support latency-sensitive applications such as cellular backhaul over satellite, Universal Service Obligation (USO) networks, corporate networks, Internet Service Providers, and other applications requiring high-performance IP transport in hub-and-spoke network environments. The CDM-840 also features integrated VersaFEC, a patented system of high- performance, short-block, low-latency codes that provide excellent coding gain with lowest possible latency.
Key operational features :
· Advanced Forward Error Correction (FEC) – VersaFEC low-latency LDPC
· DVB-S2 Receiver with low overhead encapsulation
· Integrated Router:
· Low Overhead Encapsulation
· Quality of Service (QoS)
· Payload Compression
· L-Band operation from 950 to 2150 MHz
· Block Up Converter (BUC) and Low-Noise Block Down Converter (LNB) support
· 20%, 25%, and 35% Rolloff
· Data Interfaces: (1X) 10/100/1000 BaseT Ethernet for Gigabit Ethernet traffic) port and
§ (1X) 10/100 BaseT Ethernet port (for management)
· Firmware – Flash Upgrading
· 1:1 redundancy switch compatibility
The CDM-840 is compact – 1RU high X 16.18” deep – and consumes 20 watts at 110V input (maximum, without BUC supply) or 245 watts (maximum, with BUC supply).
The CDM-840 utilizes a high performance processor and a real-time operating system (RTOS) combined with multiple Field Programmable Gate Arrays (FPGAs) for optimal performance. All non-volatile memory is provided onboard. Field upgrades are easily uploaded via satellite or the Ethernet port; software-based options are added to the unit via FAST (Fully Accessible System Topology) upgrade.
The CDM-840 runs on an embedded operating system and does not have moving parts for media storage. This design provides carrier class reliability and high speed, purpose-driven processing. The unit can be managed through multiple interfaces providing options for both in-band and out- of-band monitor and control:
· SNMP MIB II and Private MIB
· HTTP Web-based Management
· EIA-232 serial remote control
The CDM-840 supports reception and transmission of IP data over satellite links via two fundamentally different types of interface – IF and data:
• The IF interface provides a bidirectional link with the satellite via the uplink and downlink equipment.
• The data interface is a bidirectional path, which connects with the customer’s equipment (assumed to be the DTE) and the unit (assumed to be the DCE). All terrestrial data is connected using the available 10/100/1000 BaseT Ethernet interface.
The platform includes support for Constant Coding and Modulation (CCM) operation. CCM allows operators to define groups of remotes that can have different modulation and coding parameters to improve efficiency on existing satellite capacity.
On the transmit side: The return modulator transmits IP datagrams and is compatible with Comtech EF Data’s CDD-880 Multi-Receiver Router(s) located at a hub site.
In the FEC encoder, the data is differentially encoded, scrambled, and then VersaFEC-encoded. Following the encoder, the data is fed to the transmit digital filters, which perform spectral shaping on the data signals. The resultant I and Q signals are then fed to the BPSK, QPSK, 8-QAM, or 16- QAM modulator. The carrier is generated by a frequency synthesizer, and the I and Q signals directly modulate this carrier to produce an IF output signal.
On the receive side: The DVB-S2 demodulator supports enhanced GSE decapsulation and label filtering for up to 2,047 unique labels.
DVB-S2 Receiver: The CDM-840’s demodulator supports DVB-S2 QPSK, 8-PSK, 16-APSK and 32-APSK demodulation up to 62 Msps with receive data rates up to 167 Mbps depending on the modulation type and code rate. In DVB-S2 operation, the receiver operates in the CCM , VCM and ACM mode. The receiver automatically detects for spectral inversion and pilots ON/OFF, and supports spectral rolloff of 20%, 25% or 35%.
Return Channel ACM
• Based on VersaFEC ACM
• Only product to support ACM with E1 RAN while maintaining service quality
• ACM allows for automatic change in modulation and code rate in response to changing link conditions
– Converts link margin into increased capacity
– Optimizes channel coding and modulation on a frame-by-frame basis
– Allows each remote to operate optimally subject to antenna size, location within the footprint, rain fade and other impairment
Low Overhead Framing
• Most efficient framing / encapsulation
• Ultra low overhead Streamline Encapsulation (SLE)
• Patent pending
• Reduces encapsulation overhead
• Up to 65% compared to HDLC
• Up to 95% compared to DVB-RCS
• Up to 90% compared to other VSATs
• Enhanced Generic Stream Encapsulation
• 70-80% more efficient compared to MPE
• 20-30% more efficient compared to GSE
