INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS Int. J. Satell. Commun. 17, 129 } 141 (1999) Quality of service-oriented protocols for resource management in packet-switched satellites A. Iuoras*, P. Takats, C. Black, R. DiGirolamo, E. A. Wibowo, J. Lambadaris and M. Devetsikiotis EMS Technologies Canada Limited, 21025 Trans-Canada Highway, Ste-Anne-de-Bellevue, Que., Canada, H9X 3R2 SpaceBridge Networks Corporation, 715 Champlain Street, Hull, Quebec, Canada, J8X 3R1 Carleton University, Department of Systems and Computer Engineering, 4442 MacKenzie Building, 1125 Colonel By Drive, Ottawa, Ont., Canada K16 5B6 SUMMARY 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 tra$c/service classes as de"ned by ATM forum. At the core of the bandwidth allocation a novel uplink (UL) access protocol is proposed, based on a Multi-Frequency Time Division Multiple Access (MF-TDMA) primary access scheme, in conjunction with a downlink (DL) access protocol based on a more traditional Time Division Multiplex (TDM) scheme. This UL access protocol is complemented by a rate-based congestion control protocol (consistent with ATM Forum recommendations), which is an adaptation to GEO satellites environment of the Explicit Rate Indication for Congestion Avoidance (ERICA) algorithm developed for terrestrial networks. The performance of both UL access and congestion avoidance schemes has been evaluated through extensive simulations and the results compared with those obtained with other protocols or by analytical approximations. Copyright  1999 John Wiley & Sons, Ltd. 1. Introduction Broadband satellite networks are becoming an important segment of the global communication infrastructure, due to their wide geographical coverage, quick and cost-e!ective deployment and con"guration #exibility. They are required to provide seamless integration of applications and services which have traditionally been available via terrestrial networks. In order to ensure inter-operability between terrestrial and satellite networks, e!orts have been made to expand the existing protocols to satellite environment or to develop new satellite-speci"c protocols. In a satellite network the satellite resources (bandwidth, bu!ers) are shared by a relatively large population of terminals, connected to end-users and sending tra$c corresponding to various applications. Each application is associated with a service type, characterized by a tra$c descriptor and speci"ed Quality of Service (QoS). The challenge in the system design is to ensure e$ciency and fairness in satellite resources allocation to all contending terminals, while guaran- teeing the QoS for each connections (i.e. ensuring the availability of the resources required to satisfy the performance of that connection). * Correspondence to: A. Iuoras, EMS Technologies Canada Limited, 21025 Trans-Canada Highway, Ste-Anne-de- Bellevue, Quebec, Canada H9X 3R2. E-mail: aiuoras@spar.ca CCC 0737}2884/99/030129}13$17.50 Copyright  1999 John Wiley & Sons, Ltd. Accepted February 1999