IJSC Special Issue on ASMS2003

Industrial and scientific interest is growing anew in the field of mobile satellite communications, after the downturns at the end of the last millennium and the consequent unavoidable difficulties for the entire sector. In the year 2001, the Task Force on Advanced Satellite Mobile Systems (ASMS-TF) was founded at the initiative of the European Commission (EC) and of the European Space Agency (ESA), to foster this industrial segment and ensure that the upcoming market and business opportunities are exploited to their fullest. The ASMS-TF works on several fronts, including market studies, research and development, test and demonstration, regulatory and standardization issues, along with public relations and publicity. Indeed, to the end of disseminating to the widest possible audience the culture and the new findings in the field of mobile satellite communications, the ASMS-TF has organized the ASMS2003 conference, which was held at the ESA/ESRIN premises in Frascati (Italy), on July 10–11, 2003. This special issue of the International Journal of Satellite Communications collects the extended versions of some of the best papers presented at this conference. In order to place the special issue into context, the introductory paper is devoted to a description of the ASMS-TF. It is authored by G. J. King and the undersigned, and dwells upon the objectives, vision, and structure of the ASMS-TF, which enjoys a fast growing membership, now counting up to more than sixty entities, encompassing all sectors of the mobile satellite value chain. The following five technical papers address themes that span across all communication layers, starting from physical layer technologies, and then up to access control and scheduling, routing, transport protocols and system architecture considerations. The first technical paper, entitled ‘Layered Coding for Satellite-plus-Terrestrial Multipath Correlated Fading Channels’, by A. Levissianos, G. Metaxas, N. Dimitriou and A. Polydoros, focuses on a layered-coding approach for a meshed GEO-satellite and terrestrial system providing multicasting multimedia services. Through a mathematical formulation of the problem, based on information theory, and numerical simulations, the Authors test several layered-coding structures with different sets of constituent codes, particularly focusing on the trade-off between performance, throughput and complexity. The second paper, ‘Packet scheduling for the delivery of multicast and broadcast services over S-UMTS’, by M. Karaliopoulos, P. Henrio, K. Narenthiran, E. Angelou, and B. G. Evans, is concerned with packet scheduling management for broadcast/multicast satellite networks over terrestrial UMTS, as developed in the IST project SATIN. Two known packet scheduling approaches are adapted for use in the proposed system. Their performance is evaluated via simulations in terms of ability to meet the packet-level QoS requirements of individual flows, fairness with respect to different flows, handling priority, and efficiency with respect to the system resources.