Cooperative Medium Access Control Protocol Design in Distributed Wireless Network
Date Issued
2009
Date
2009
Author(s)
Chung, Guo-Feng
Abstract
Transmission reliability is one of the most important issues in wireless communi-ations. Different techniques have been proposed to improve transmission reliabilityn both physical (PHY) and medium access control (MAC) layers. Inspired by theulti-input multi-output (MIMO) system, cooperative transmission was introducedo obtain diversity gain without the complexity of using multi-antenna radios. Thisdditional gain, when being used properly, can improve transmission reliability oreduce power consumption.n cooperative transmission, neighbors of the source device, referred to as relays,orward the data frame received from the source device to the destination device. Tonable such cooperation, devices including the source, the relays, and the destinationust know (1) when to cooperate and (2) whom to cooperate with. To address thesessues, MAC-layer signaling and coordination among the three parties are needed.n this thesis, we design a new medium access control (MAC) protocol that sup-orts cooperative transmission. The new protocol enables devices to adapt trans-ission schemes (direct or cooperative) to dynamic wireless environments. With ourrotocol, the devices exchange the link information and perform relay selection — viaontention — in a fully distributed manner. In order to select the best relay, we alsontroduce a ”busy-tone” relay raking system. To further improve the performance, cross-layer optimization technique, namely adaptive modulation, is integrated intour protocol.e performed mathematical analysis and conducted extensive simulation in Opnetodeler to show the performance. The overall throughput improvement varies from0% to 20% in low-SNR environments. The results show that our protocol is a feasibleisolution and delivers considerable improvement even when taking into account allignaling overheads.
Subjects
cooperative transmission
MAC protocol
diversity gain
relay
adaptive modulation
distributed networks
Type
thesis
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