Multi-frequency Time Division Multiple Access Research Articles

Interactive channel for multimedia satellite networks

Multimedia, including Internet traffic, can currently be multiplexed within the DVB/MPEG-2 formats and delivered direct to home users. Traditionally a slow terrestrial telephone link between the user and Internet service provider is used to request data. A direct return channel system will facilitate users' high-bit-rate bidirectional communication via satellite. The return link could be used for the fast Internet access or large data exchanges that will be necessary in a multimedia world. The satellite system not only removes the need for wires but also increases transfer speeds. Satellite interactive terminals can establish network connections via satellite and a ground-based hub. The DVB/MPEG-2 format carries up to 45 Mb/s in the forward link, and a multifrequency time-division multiple access scheme allows up to 2 Mbit/s in the return direction. The return channel of the interactive channel for multimedia satellite networks underwent final standardization by ETSI in early 2000. This article reviews the system concept of a typical implementation. The key features of the return channel air interface, from transmission parameter to login procedure, are explained. In general, Internet packets are expected to be carried via DVB/MPEG-2 in the forward direction and via ATM in the return direction. The IP transportation techniques are described.

Quality of service-oriented protocols for resource management in packet-switched satellites

The present paper deals with bandwidth allocation and congestion avoidance in a broadband satellite with on-board switching, oriented towards guaranteeing the Quality of Service (QoS) associated with various traffic/service classes as defined by ATM forum. At the core of the bandwidth allocation a novel uplink (UL) access protocol is proposed, based on a Multi-Frequency Time Division Multiple Access (MF-TDMA) primary access scheme, in conjunction with a downlink (DL) access protocol based on a more traditional Time Division Multiplex (TDM) scheme. This UL access protocol is complemented by a rate-based congestion control protocol (consistent with ATM Forum recommendations), which is an adaptation to GEO satellites environment of the Explicit Rate Indication for Congestion Avoidance (ERICA) algorithm developed for terrestrial networks. The performance of both UL access and congestion avoidance schemes has been evaluated through extensive simulations and the results compared with those obtained with other protocols or by analytical approximations.