Asymmetric high speed data in Inmarsat

Mobile Experimental Broadband Interconnection using Satellites (MOEBIUS) is one of the projects funded by the European Community under the RACE (Research and Development for Advanced Communication in Europe) initiative. The MOEBIUS project was established to ensure that the European Community gains maximum benefit from existing and emerging mobile satellite technologies. Its mission is to develop multimedia platforms for specific applications in the maritime and land mobile communities. The MOEBIUS project demonstrated the benefits of Inmarsat duplex high speed data (DHSD) service for various applications, e.g. remote expert support, high quality audio transmissions, high data-rate file exchange etc. However, it was found that for certain applications a higher than 64 kbps data rate from mobile to fixed subscriber might be more efficient. This led to an idea of an asymmetric satellite service offering n×64 kbps (n=1 to 6) in one direction (mobile to fixed) and voice or m×64 kbps (m⩽6) in the fixed-to-mobile direction. The concept of asymmetric high speed data (AHSD) services can assist to use limited bandwidth and power in a cost efficient way. Different aspects of AHSD in Inmarsat are discussed