In this paper, several TDMA-based packet multiple access protocols are studied and evaluated in the geostationary satellite environment. The distributed queueing random access protocol, DQRAP, originally proposed for HFC networks is adapted to the satellite environment. Another protocol, the announced retransmission random access protocol, ARRA, proposed for wireless networks is also studied. Both protocols are modeled and simulated in a VSAT network context. We then propose a new protocol which combines the advantages of both studied schemes and is more adapted to interactive multimedia applications over satellite uplinks. The generalized retransmission announcement protocol, GRAP, regroups the immediate access by contention at low loads, and the reservation access. At higher loads, to achieve a better channel efficiency. An analytical model is proposed to calculate the channel throughput obtained by GRAP under different loading conditions. Simulation results illustrate an improved throughput/delay characteristics and a higher protocol stability compared to both DQRAP and ARRA. Enhanced versions of the protocol are also proposed and evaluated to further improve its efficiency, with reasonable additional complexity.

Multiple access to the radio channel is a very important aspect that determines the efficiency of wireless networks. In this paper, we propose a packet multiple access protocol for uplink satellite channels characterized by their long propagation delay. The generalized retransmission announcement protocol, GRAP relies on a framed channel structure, allowing user access by either direct contention or reservation. This hybrid access scheme is proven to be more efficient in following the dynamic load variations of the satellite system. The different features and operation of GRAP are explained in this paper. An analytical model is developed to calculate the numerical channel throughput achieved by GRAP for different traffic loads.

This work focuses on resource allocation and connection admission control (CAC) issues in broadband satellite networks. Broadband services can now be provided by satellite systems operating in the Ka band, due to the large bandwidth available at such frequencies. In this context, we propose a resource allocation algorithm which integrates three classes of services at the MAC layer: constant bit rate (CBR), bursty data, and best effort services. The double movable boundary strategy (DMBS) is proposed to establish a resource-sharing policy among these service classes over the satellite uplink channel. The DMBS is a dynamically controlled boundary policy which adapts the allocation decision to the variable network loading conditions. Connection-oriented and connectionless services can be supported by the system. The CAC and slot allocation decisions are taken at the beginning of each control period after monitoring the filling level of traffic request queues. A threshold level for the bursty data request queue is defined to regulate the CAC process. The impact of the queue threshold value on the performance of the DMBS allocation policy is particularly evaluated in this study. A dynamic variation of this value is also proposed to enhance the system response to interactive applications. We present a brief analytical formulation for the DMBS model, together with simulation study details and performance evaluation results. The obtained results indicate a good efficiency, in terms of overall channel throughput and CBR blocking probability, for both fixed and dynamic data queue threshold approaches. The dynamic approach, however, outperforms the fixed one in terms of overall encountered bursty data delay.

The movable-boundary integrated CBR/bursty-data traffic, MB-ICBT, is a new version of hybrid protocols supporting both, circuit- and packet-switching techniques in VSAT network environments. Circuit-switching is applied to CBR traffic connections, which are admitted in the system on a DAMA basis. Bursty-data traffic, on the other hand, is allowed to contend randomly, sending simultaneously an anticipating reservation. A movable boundary policy is applied between the two traffic compartments to adapt to network loading conditions. The introduction of the anticipated reservation access for bursty-data, together with the movable-boundary policy, serve to minimize the collision resolution delay, largely significant in VSAT networks. The MB-ICBT protocol is analysed and simulation results verify the enhanced performance in terms of access delay for bursty-data traffic together with an improved overall channel throughput.