“SED provided a complete turnkey solution, installing a fully-operational system on time and on budget that met or exceeded all our requirements. Today the system continues to provide the reliable service we demand to keep our customers satisfied. As our network expands and new services are added, we keep going back to SED for management system solutions. We are confident that SED will continue to provide the performance we need.”
We have first-hand experience designing, building, and integrating purpose-built resource management systems for satellite communications. These systems are designed to maximize the usage of limited satellite and network resources while maintaining quality of service requirements. Typically, integrated into the gateway or central operations center of a communications service provider, these highly-available software systems provide real-time management of network resources at the global, national, and gateway basis. We have proven system designs, extensive domain knowledge, and custom software frameworks upon which to implement solutions.
Designed and built by SED, the Global Resource Manager (GRM) is a real-time software system that dynamically manages the payload resources of the Inmarsat-4 satellites. Interfacing with the Inmarsat-4 network and satellite ground control systems, the GRM selects, prioritizes, and establishes communication channels on the satellite in response to traffic demand on a 3G-based BGAN network.
The GRM is designed to maximize space segment usage while ensuring service quality. By modeling the signal to noise ratios (SNR) of active carriers, the GRM prioritizes and selects channels, maximizing frequency reuse across the wide and narrow spot beams and dynamically managing SNR via power constraints and C/I models. An operator-configurable resource management algorithm enables spectrum planning engineers to meet their on-going tactical and strategic needs.
The GRM is a technically sophisticated system designed to manage a technically sophisticated satellite. Unlike traditional bent-pipe satellites, the Inmarsat-4 satellite is built with digital channelizers, beamformers, and powerful digital signal processors. Designed specifically to accommodate mobile communication, the payload is capable of dynamically switching hundreds of channels between 256 beams. In order to maximize the efficiency of the onboard digital resources, the GRM monitors the payload status in real-time and dynamically reconfigures the channel switching to accommodate bandwidth allocations on the ground.
Implemented using the SED high-availability software framework, the GRM is a critical system in the operation of the global Inmarsat-4 network. Each GRM is fully redundant, having an active hot-standby configuration and an off-site, warm-standby system for disaster recovery.
SED delivered the turn-key GRM in 2003 and continues to provide technical support, maintenance, and enhancements to Inmarsat as their commercial needs evolve and new services are offered. SED is currently enhancing the GRM to support the Alphasat satellite, which has an extended L-band range and an even more powerful digital payload.
Similar to Inmarsat-4, SED’s systems plays an integral part in the real-time management of the Inmarsat-3 satellite resources. Centralized Network Coordination Stations (NCS), designed and built by SED, coordinate the usage of shared satellite resources amongst multiple geographically-separated ground gateways. The gateways, using out-of-band satellite control channels, communicate with the NCS to acquire demand assigned shared channels for short-to-medium duration SCPC-based services such as voice, fax, and ISDN.
Rather than dividing the limited spectrum between gateways that may have varying diurnal traffic profiles, the NCS offers a sophisticated planning mechanism that allows spectrum to be shared by different services having different waveforms, bandwidths, and power requirements. Services can be prioritized and the NCS supports preemption to accommodate critical services, such as safety and emergency. Additionally, occasional, off-peak, and long-term spectrum leases are accommodated using autonomous scheduling mechanisms and, in some cases, dedicated systems.
Originally installed in 1998, SED has successfully supported and evolved the NCS for almost 15 years, including 6 global locations and multiple relocations. Through SED’s commitment to retain system knowledge and continual software and hardware improvement, Inmarsat has enjoyed commercial success of the Inmarsat-3 network for a satellite lifetime and more.
In 2009, Hughes was contracted to develop the next generation core architecture for the Globalstar mobile satellite phone and low-speed data communications network. Backed by solid performance on previous outsourcing efforts, SED was sub-contracted by Hughes to design, develop, deliver, and support the Resource Management System (RMS) component of the Globalstar Radio Access Network (RAN) gateways.
The RMS is a highly-available fault-tolerant software system that manages the data-path components of the RAN in real-time to provide pre-planned service to beams and sub-beams during each pass of the low-earth orbit satellites. During each pass, in preciously timed intervals of milliseconds, the RMS allocates portions of the payload’s available power to each beam providing service. At each interval, the RMS allocates power based on received power utilization reports and requests for additional power while considering the satellite, polarization, and beam power limits. Power demands that exceed limits are reduced based on configured priority for various categories of demand. The RMS also manages the payload’s longer-term power requirements, including monitoring satellite power usage over time and reducing the received satellite power limits as needed to ensure that satellite energy limits are not exceeded over the satellite visibility period.
The TerreStar satellite mobile communications service that combines cellular wireless connectivity with a GEO satellite network. Using innovative ground-based beam forming (GBBF) spot beam technology, the network allows TerreStar to dynamically reposition beams to be able to allocate power and spectrum to situation-specific incidents ensuring capacity when and where it is needed.
SED was sub-contracted by Hughes to design, develop, deliver, and support a combined Packet Resource Management System / Local Resource Manager (PRMS/LRM) subsystem for integration into the Hughes-design Satellite Access Station (SAS) gateway. As an integral component to the SAS, the PRMS/LRM was designed by SED to be a highly-available fault-tolerant software system.
The LRM component receives high-level resource plans from a centralized global resource manager, channelizes the available spectrum and power based on time of day plans, and provides the channels to the PRMS component for assignment to the SAS channel units and processing elements. The PRMS component manages the utilization of the channel units and processing elements, configures the carriers for assigned channels, and monitors the traffic load on each of the configured carriers. The PRMS requests additional channels from the LRM for over-utilized beams and returns channels from under-utilized beams.
In 2001, SED worked under sub-contract to Hughes to assist in developing the Inmarsat Early Entry (IEE) packet data satellite communications system. The IEE system, also known as R-BGAN, is the precursor to the current Inmarsat-4 BGAN system. SED was initially contracted to provide on-site consulting during the requirements analysis and system design phase of the IEE program. On completion of the consultation, SED was further sub-contracted to design, develop, install, and support the PRMS subsystem of the IEE gateway system.
The PRMS is a highly-available fault-tolerant software subsystem that is responsible for determining when and where satellite channels are to be reused (which sub-beams), assigning channels to gateway channel units and processing elements, and assigning users to carriers as they access the gateway. The PRMS manages configuration of carriers on the allocated satellite channels by selecting and configuring appropriate equipment. Using utilization reports and requests for service, received from the gateway processing elements, the PRMS periodically performs a ranking to determine the number of satellite channels needed to service the current traffic demands in each sub-beam. The results of the periodic ranking result in new carriers being set up to satisfy high user demand and under-utilized channels being returned for reallocation by first coordinating the reassignment of allocated users. Additionally, the PRMS manages the power level of each carrier, and coordinates the abatement of over-assigned channels.
In 1997, prior to the introduction of UMTS mobility management, SED provided a turn-key Mobility Management System (MMS) to Inmarsat to allow the users of its B, M, and Mini-M services to access terminals using one Single Network Access Code (SNAC).
Utilizing the terminal’s network registration process, the MMS interfaces with the ground gateways and coordinating stations to obtain, maintain, and distribute mobile location information. Two MMS systems located at opposite sides of the world collect information on terminals located in visible satellite coverage areas. Using a terrestrial inter-connect, the two MMS systems exchange location information to create two complete and replicated global databases. The two MMS systems synchronize the information, via satellite and terrestrial connections, to local databases stored at each gateway, where it is used to route terrestrial-originated requests to the gateway where the terminal connected to obtain service.