Performance of Combined Free/Demand Assignment Multiple-Access Schemes in Satellite Communications

Abstract

By combining free assignment with demand assignment, the combined free/demand assignment multiple‐access (CFDAMA) protocol offers a much shorter delay at low and medium traffic loads while maintaining the high channel utility of the demand‐assignment multiple‐access (DAMA) technique. In these schemes, reservation can be made using pre‐assigned (PA) or random‐access (RA) request slots, or piggy‐backing (PB) the request on a data packet. This paper presents a performance analysis of CFDAMA schemes in packet satellite communications. Illustrative examples are given. They show a good agreement between analytical and simulation results. For low and medium sizes of terminal population, the CFDAMA‐PA scheme has an excellent delay‐throughput performance. As the terminal population increases, its performance is gradually degraded due to the long waiting time for a request. For a very large number of terminals, the CFDAMA‐RA becomes more effective than CFDAMA‐PA. This indicates that a CFDAMA scheme using a hybrid PB/RA requesting protocol can provide the best performance for a wide range of terminal population sizes.

Using traffic prediction and estimation of provider revenue for a joint GEO satellite MAC/CAC scheme

“…A reservation subchannel is necessary for users to communicate with each other, since they are distributed; hence only one station can access the channel at a time. e. Hybrids of Random Access and Reservation Protocols [2,[26][27][28][29][30][31][32]. They are designed in order to combine the advantages of the above categories for achieving better QoS for the users.…”

“…This approach was proposed for the first time in the relevant literature in the CFDAMA scheme [28,29], which was one of the first hybrid protocols (according to the classification in Sect. 2) to be proposed; the algorithm implemented in our scheme is a simple round-robin assignment algorithm to all RCSTs which are currently active, however it differs from [18] in that FPRRA's algorithm is fair to video terminals who have been allocated a smaller amount of bandwidth than other video terminals of the same priority type.…”

“…This distribution of the remaining bandwidth is especially useful in allocating slots to video users, as the difficulty in providing them with adequate bandwidth due to their frequent changes in bandwidth needs could be somewhat alleviated by their acquiring the unused channel bandwidth freely in a round-robin manner. Similarly to [29], user stations send their capacity requests embedded in the header of their packets (in our protocol, these requests are very rare, for reasons explained below). The free capacity distribution performed by the protocol brings the end-to-end delay performance at low loads close to that obtained with random access protocols, while the demandbased bandwidth allocation at the beginning of each frame guarantees the protocol's stability, robustness and efficient utilization of transmission bandwidth at high loads.…”

On providing dynamic resource allocation based on multimedia traffic prediction in satellite systems

“…(e) Hybrids of Random Access and Reservation Protocols [17,19,[23][24][25][37][38][39]. The protocols which belong in this category (PRRA belongs in this category as well) are designed in order to combine the advantages of the above categories for achieving better QoS for the users.…”

Satellite bandwidth allocation based on MPEG-4 videoconference traffic prediction

“…We use the Combined Free and Demand Assignment Scheme with Piggybacking (CFDAMA-PB) version of the protocol, which was shown in Ref. [8] to be the most efficient way of making reservations. According to the PB strategy, user stations send their capacity requests embedded in the header of their packets.…”