| Summary: | Over the past several years, a number of new satellite systems have been proposed in an
attempt to provide high-speed Internet and multimedia services to businesses and home users.
These proposals are driven by network operators' desire to reach end users who do not have cost
effective access to other alternatives, such as fiber and cable. While the use of satellites provides
the most flexible way to globally extend networks, most protocols are optimized to run on terrestrial
networks. The primary differences between terrestrial and satellite connectivity are the link
latency and error rates. Satellite links often suffer higher error rates and larger latency than terrestrial
links. Terrestrial links also have much more available bandwidth than their satellite counterparts,
making satellite bandwidth a precious resource that cannot be wasted.
A number of network applications require the use of reliable multicast protocols to
disseminate data from one source to a potentially large number of receivers. Broadband satellite
networks are well suited to support such applications. Although reliable multicast protocols for
the Internet have received much attention, not much work on these protocols for satellite networks
has been conducted. The objective of our work is to develop window-based, satellite reliable
multicast transport protocols (SRMTPs) for bulk data transfer over broadband satellite networks.
The proposed protocols guarantee reliability while achieving high throughput and maintaining
low end-to-end delay. Satellite onboard processing (OBP) is used to split uplink and downlink
channels. A different automatic retransmission request (ARQ) is used for error recovery in each
link. OBP can detect uplink packet losses in advance and report the losses to the source, thus
avoiding the uplink losses faced by all downlink users. Onboard buffering (OBB) is employed to
recover downlink errors to reduce retransmission time. We evaluated the SRMTP's performance through simulations. Results show that SRMTP generally outperforms the existing multicast
protocol, MFTP (Multicast File Transfer Protocol), in terms of network delay and system
throughput. The performance is further enhanced by OBP and OBB. Based on the simulation, we
contend that SRMTPs are indeed scalable, efficient reliable multicast transport protocols over
satellite broadband networks.
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