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Evènements et manifestations

18/10/2014

Doctorate thesis defense of Maymouna BEN SAID




Doctorate thesis defense on Saturday October 18th 2014, at 09h00, Amphi I at Sup'Com


Entitled : ARQ Protocols for Cooperative Systems

Presented by : Maymouna BEN SAID 



Committee


President

Monia TURKI

Professor, ENIT – Tunisia

 

 

 

Reviewers

Mohamed IBNKAHLA

Professor, Queen’s University – Canada

 

Noura SELLAMI

Associate Professor, ENIS – Tunisia

 

Examiner

Fatma ABDELKEFI

Associate Professor, Sup'Com – Tunisia

 

Thesis director

Hatem BOUJEMAA

Professor, Sup'Com – Tunisia


Abstract


With the deployment of multimedia services and streaming for mobile devices, the demand for high-speed reliable data increases progressively. In this respect, cooperative automatic repeat request (C-ARQ) protocols have been considerably acknowledged as being efficient to combat channel impairments. The concept of C-ARQ protocol is to exploit the broadcasting nature of the wireless channel jointly with the receiver feedback. Thereby, a set of relay nodes are placed between the sender and the receiver, whose overheard the direct transmission, can assist the communication when requested. At the receiver and upon each packet decoding failure, a retransmission is requested until error-free reception. Although the spatial diversity and the feedback exploitation benefit and under poor channel conditions, the throughput performance of C-ARQ can be badly affected; In that way, several cooperation schemes have been questioned. This thesis investigates the throughput performance of C-ARQ protocols with different cooperation schemes. After providing a detailed study on the throughput performance of C-ARQ protocol in the presence of single/multiple antenna terminals; we focus on the multi-node cooperative ARQ protocol. Two main subject areas are questioned; relay selection and hybrid relaying. Concerning the first aspect, we first carry out an extensive study on the opportunistic relaying and we derive close-form expressions for the throughput with amplify and forward (AF) and decode and forward (DF) relaying modes. Second, we address the partial relay selection (PRS) ARQ protocol and we present a study on the throughput, the queuing and transmission delays. As for the second aspect, we propose a new static hybrid AF-DF ARQ protocol with opportunistic relaying. When a relay is close to source, it operates in AF mode otherwise, it operates in DF mode. The relay node that offers the high instantaneous signal to noise ratio of the relaying link is selected to retransmit the data packet. Simulation results showed that the proposed algorithm may offer same performance as opportunistic DF with a lower complexity.


Finally, in the fourth part of our work, we tackle C-ARQ protocol modeling. We first propose a three state Markov chain model convenient for dual-hop ARQ protocol with DF relaying over channels with memory. Furthermore, an extended (N + 2) − state Markov chain model for multi-hop ARQ with N relays over block fading channels is developed.


Keywords

Cooperative systems, ARQ protocols, relay selection, hybrid relaying, throughput analysis.