Inmarsat-4 GRM


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.