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Chaoub A.,Mohammed V University | Ibn-Elhaj E.,National Institute of Posts and Telecommunications
Computers and Electrical Engineering | Year: 2013

This study addresses the reliability of secondary multimedia transmissions under delay constraints and lossy conditions. In particular, a cognitive radio (CR) infrastructure collocated with a licensed network is considered. The primary traffic evolves following a Poisson distribution. During the sensing operations, the best spectrum opportunities are identified using a new subchannel quality metric. To mitigate the effects of packet loss, the use of a multiple description coding (MDC) framework of the unequal loss protection (ULP) class is explored. The performance of the proposed scheme is evaluated by comparing the results with those of the traditional equal loss protection (ELP) technique. Finally, a general cross layer model is proposed to ensure end-to-end message delivery in realistic cognitive radio contexts, which are characterized by difficult primary signal detection and random primary interruptions, in addition to subchannel impairments. Numerical simulations are conducted to investigate the peak signal-to-noise ratio (PSNR) benefits of the proposed system using both ULP and ELP schemes. © 2012 Elsevier Ltd. All rights reserved. Source


Chaoub A.,Electronic and Communication Laboratory | Elhaj E.I.,National Institute of Posts and Telecommunications | El Abbadi J.,Electronic and Communication Laboratory
Communications in Computer and Information Science | Year: 2011

In this paper, we propose a solution to multimedia transmission problem over Cognitive Radio networks in lossy environments. For Cognitive Radio networks where the spectrum is owned by Primary Users having Poissonian traffic, Secondary Users are allowed to use these spectral resources for some delay constrained multimedia applications. The service provider produces layered stream based on a progressive source coder like SPIHT. We use a specific packetization framework for Multiple Description Coding derived from the Priority Encoding Transmission to cope with both primary traffic interruptions and subchannels fading. An efficient exhaustive algorithm that implements an Unequal Loss Protection mechanism will be introduced to maximize the received PSNR as a function of our transmission model parameters. Numerical simulations for image transmission case show that the proposed scheme can protect the important layers from packet losses to a meaningful degree and improves the perceived image quality even when packet losses increase. © 2011 Springer-Verlag. Source


Chaoub A.,Laboratory of Electronic and Communication | Elhaj E.I.,National Institute of Posts and Telecommunications | Abbadi J.E.,Laboratory of Electronic and Communication
International Conference on Multimedia Computing and Systems -Proceedings | Year: 2011

Cognitive Radio networks are emerging as a new paradigm of communication and channels sharing in multimedia and wireless networks. In this paper, we consider multimedia traffic transmission over shared Cognitive Radio (CR) networks using fountain codes under different subchannel selection policies in a fading environment. We assume that the primary traffic arrival follows a Poisson process. To share this CR infrastructure, we propose to make use of the Time Division Multiple Access (TDMA) method, each secondary user (SU) is assigned one time slot where he transmits with a certain probability, the proposed model permits to this SU to transmits also in the remaining slots if he has data to transmit and has missed his own slot. Therefore, packets are not only lost by reason of Primary traffic interruptions, but also we consider losses caused by collisions between several SUs due to our specific time slot allocation. We evaluate the influence of the proposed model parameter settings on the secondary traffic transmission performance in view of the Spectral Efficiency. Numerical simulations show that the system still exhibit good secondary traffic efficiency despite of the presence of primary interferences and secondary collisions. © 2011 IEEE. Source


Chaoub A.,Mohammed V University | Ibn-Elhaj E.,National Institute of Posts and Telecommunications
Proceedings of the Mediterranean Electrotechnical Conference - MELECON | Year: 2012

In this paper, we treat the problem of delay constrained multimedia applications over Cognitive Radio (CR) networks under Binomial primary traffic arrival. Secondary Users (SUs) share the spectrum holes using the TDMA method based on the Opportunistic Spectrum Access. Primary traffic interruptions and the concurrent secondary access to spectral resources are major reasons for packet losses. Thereby, we use a specific packetization framework for Multiple Description Coding to cope with both primary interruptions and secondary collisions. Numerical simulations, in view of the Spectral Efficiency, show the effectiveness of the proposed solution in dealing with dynamics between primary and secondary users. © 2012 IEEE. Source


Chaoub A.,Mohammed V University | Elhaj E.I.,National Institute of Posts and Telecommunications
2011 3rd International Conference on Next Generation Networks and Services, NGNS'2011 | Year: 2011

Cognitive Radio is an enabling technology for communication and channels sharing in multimedia and wireless networks. In this paper, we consider multimedia traffic transmission over shared Cognitive Radio (CR) networks using fountain codes. To share this CR infrastructure, we propose to make use of Time Division Multiple Access method based on the opportunistic spectrum sharing. Each Secondary User (SU) is assigned one time slot where he transmits with a certain probability. The given model allows each SU to transmit in the remaining slots if he has data to transfer and has missed his own slot. Therefore, the reasons for packet loss are twofold: Primary traffic interruptions and collisions between several SUs due to our specific time slot allocation. We use a redundancy-based model for link maintenance to compensate the spectrum resources loss caused by the primary traffic reclaims. Moreover, we setup up many Secondary User Links to minimize the collision effects in order to meet the QoS requirements for multimedia communication services. Numerical simulations, in view of the average Goodput, show that the system still exhibit good secondary traffic robustness despite of the presence of primary interferences and opportunistic transmission collisions. © 2011 IEEE. Source

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