The BGAN Modem Subsystem (BMS) provides software PHY functionality for an Inmarsat BGAN terminal. The BMS in concert with a customer-furnished protocol stack implements the complete Access Stratum of the IAI-2 air interface (the BGAN waveform). The BGAN Modem Subsystem is comprised of:

• BGAN Decoding Subsystem (BDS) for baseline, BGAN-X and LDR/HDR bearers
• BGAN Forward Demodulator Subsystem (BFDS) for baseline, BGAN-X and LDR/HDR bearers
• BGAN Return Modulation Subsystem (BRMS) for baseline, BGAN-X and LDR/HDR bearers
• BGAN software Turbo decoder or FPGA Turbo decoder interface
• Real-time framework with OS abstraction layer
• Modem application

The BPLT/UT Interface (BUI) functional block, which is required in order to interface to the BPLT when running the UT physical layer Mandatory Test Requirement scripts (UTMTRs), is also available. The BFDS is operational in SwiftBroadband (SBB) UTs from several vendors and the BMS is employed in Inmarsat’s BGAN Radio Module (BRM). The BMS has also been integrated into an SB-SAT terminal, supporting BGAN connectivity from LEO satellites.