2 research outputs found

    Multicast communication support over satellite networks

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    In this dissertation, we focus on providing multicast communication support over satellite networks. We investigate the possible performance enhancements in terms of the throughput, capacity, and scalability of a Ka-band, multiple spot-beam satellite communication system that supports unicast and multicast services. The role satellite systems play in today's communication infrastructure is changing rapidly, fueled by the technological advance in the design of new satellite systems, and by the new multimedia service applications, such as on-demand multimedia content delivery, distance learning, and distributed software updates that would benefit from the wide-area coverage, direct and ubiquitous access capability of the satellite systems. These applications require concurrent transmission of the same content to multiple users. In order for multicasting-based services to grow over satellite networks, there must be an incentive to deploy them. We address the problem of user heterogeneity that occurs when multicast users that are located across several different spot-beam locations experience different channel conditions. We propose a novel power allocation scheme for smoothing out the heterogeneity experienced by the multicast groups, while making sure that unicast users get a fair share of system resources as well. Our power allocation scheme would benefit from user feedback in determining the channel conditions. However, collecting feedback from a large set of users is a challenging task in satellite systems, since access to the uplink bandwidth is to be shared between several users, and the resources are usually limited. We introduce a novel algorithm that reduces the volume of feedback information that is to be transmitted over the satellite segment of the network, while maintaining that the relevant information is collected in a timely manner. Finally, we focus our attention to the potential benefits of integrating packet level forward error correction coding to packet delivery for reliable multicast services over satellite networks. Forward error protection helps recover corrupted data, and minimizes the need for retransmissions over the satellite channel. We investigate the use of a special form of forward error correcting (FEC) code and couple it with an adaptive control mechanism to dynamically adjust the number of encoding packets forwarded to the users

    Some Design Issues of SRMTP, a Scalable Reliable Multicast Transport Protocol

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    . In this paper, we propose a transport layer protocol for oneto -many multicast that is designed to have good scalability properties in large receiver groups and provides reliable transmission. Reliability is achieved using forward error correction (FEC) in combination with selective repeat NAK-based ARQ. Using FEC can significantly reduce the necessity for retransmission requests or make them totally unnecessary, which is important in wireless and satellite communicaton environments, as well as for delay-sensitive multimedia applications. The protocol uses one multicast group address for the original transmission and a second group address for the handling of retransmissions, which helps in significantly reducing the network load on branches with low loss and facilitates usage in the context of satellite communications. We hope that our work will be useful and encouraging for the development of group communication applications. 1 Introduction Communication between peop..
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