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- 저자 : Parastoo Sadeghi (검색결과 3 건)
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Delay Tolerant Information Dissemination via Coded Cooperative Data Exchange
Shahriar Etemadi Tajbakhsh,Parastoo Sadeghi 한국통신학회 2015 Journal of communications and networks Vol.17 No.2
In this paper, we introduce a system and a set of algorithms for disseminating popular content to a large group of wireless clients spread over a wide area. This area is partitioned into multiple cells and there is a base station in each cell which is able to broadcast to the clients within its radio coverage. Dissemination of information in the proposed system is hybrid in nature: Each base station broadcasts a fraction of information in the form of random linear combinations of data blocks. Then the clients cooperate by exchanging packets to obtain their desired messages while they are moving arbitrarily over the area. In this paper, fundamental trade-offs between the average information delivery completion time at the clients and different parameters of the system such as bandwidth usage by the base stations, average energy consumption by the clients and the popularity of the spread information are studied. Moreover different heuristic algorithms are proposed to control and maintain a balance over these trade-offs. Also, the more complicated case of multiple sessions where each client is interested in an arbitrary subset of sessions is considered and two variants of the basic dissemination algorithm are proposed. The performance of all the proposed algorithms is evaluated via extensive numerical experiments.
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Shama N. Islam,Salman Durrani,Parastoo Sadeghi 한국통신학회 2016 Journal of communications and networks Vol.18 No.5
Multi-way relay networks (MWRNs) allow multiple usersto exchange information with each other through a single relayterminal. MWRNs are often incorporated with capacity achiev-ing lattice codes to enable the benefits of high-rate signal constel-lations to be extracted. In this paper, we analytically character-ize the symbol error rate (SER) performance of a functional de-code and forward (FDF) MWRN in the presence of channel esti-mation errors. ConsideringM-ary quadrature amplitudemodula-tion (QAM) with square constellations as an important special caseof lattice codes, we obtain asymptotic expressions for the averageSER for a user in FDF MWRN. The accuracy of the analysis athigh signal-to-noise ratio is validated by comparison with the sim-ulation results. The analysis shows that when a user decodes otherusers with better channel conditions than itself, the decoding userexperiences better error performance. The analytical results al-low system designers to accurately assess the non-trivial impact ofchannel estimation errors and the users’ channel conditions on theSER performance of a FDF MWRN withM-QAM modulation.
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Islam, Shama N.,Durrani, Salman,Sadeghi, Parastoo The Korea Institute of Information and Commucation 2016 Journal of communications and networks Vol.18 No.5
Multi-way relay networks (MWRNs) allow multiple users to exchange information with each other through a single relay terminal. MWRNs are often incorporated with capacity achieving lattice codes to enable the benefits of high-rate signal constellations to be extracted. In this paper, we analytically characterize the symbol error rate (SER) performance of a functional decode and forward (FDF) MWRN in the presence of channel estimation errors. Considering M-ary quadrature amplitude modulation (QAM) with square constellations as an important special case of lattice codes, we obtain asymptotic expressions for the average SER for a user in FDF MWRN. The accuracy of the analysis at high signal-to-noise ratio is validated by comparison with the simulation results. The analysis shows that when a user decodes other users with better channel conditions than itself, the decoding user experiences better error performance. The analytical results allow system designers to accurately assess the non-trivial impact of channel estimation errors and the users' channel conditions on the SER performance of a FDF MWRN with M-QAM modulation.
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