Cooperative retransmission implementation in ns 2
Master thesis
Åpne
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http://hdl.handle.net/11250/137508Utgivelsesdato
2010Metadata
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Sammendrag
From the theoretical perspective cooperative communications are reasonably well
understood. But in practical realizations of cooperative communication system are still
quite limited, the articles in this special issue are devoted to implementation aspects
related to cooperative retransmission implementation in ns 2.system..Cooperative
retransmission in wireless networks has attracted many research attentions which is the
basic idea when a receiver cannot decode a frame, the retransmission is handled not by its
original source but rather by a neighbor that overheard the transmission successfully, in
this situation may helper have a better channel to the destination and when it comes to
this topic, three key issues need to be addressed, namely when to cooperate, whom to
cooperate with and how to protect cooperative retransmission are addressed here. The
fundamental of cooperative communications lie in the physical layer. However, the
notation of cooperation is available in various forms at different protocol layer. To
facilitate access to the physical layer information and adaptation to mobility, it is natural
to introduce the notion of cooperation in the layer directly above the physical, namely,
the medium access control MAC layer; we consider the case of multiple cooperating
neighbors from a MAC-layer perspective and assume a receiver that can only decode one
transmission at a time, while multiple retransmission by several neighbors that had heard
the frame, will cause a collision, according to our protocol which we are particularly
interested in MAC protocol design for cooperative communication based on 802.11
CSMA/CA, and a cooperation is initiated only if the direct transmission fails. An optimal
relay node is selected in a distributed manner according to instantaneous relay channel
conditions in the network.
Beskrivelse
Masteroppgave i informasjons- og kommunikasjonsteknologi 2010 – Universitetet i Agder, Grimstad