The area of cooperative communications has received tremendous research interest in recent years. This interest is not unwarranted, since cooperative communications promises the ever-so-sought after diversity and multiplexing gains typically associated with multiple-input multiple-output (MIMO) communications, without actually employing multiple antennas. In this dissertation, we consider several cooperative communication channels, and for each one of them, we develop information theoretic coding schemes and derive their corresponding performance limits. We next develop and design practical coding strategies which perform very close to the information theoretic limits. The cooperative communication channels we consider are: (a) The Gaussian relay channel, (b) the quasi-static fading relay channel, (c) cooperative multiple-access channel (MAC), and (d) the cognitive radio channel (CRC). For the Gaussian relay channel, we propose a compress-forward (CF) coding strategy based on Wyner-Ziv coding, and derive the achievable rates specifically with BPSK modulation. The CF strategy is implemented with low-density parity-check (LDPC) and irregular repeataccumulate codes and is found to operate within 0.34 dB of the theoretical limit. For the quasi-static fading relay channel, we assume that no channel state information (CSI) is available at the transmitters and propose a rateless coded protocol which uses rateless coded versions of the CF and the decode-forward (DF) strategy. We implement the protocol with carefully designed Raptor codes and show that the implementation suffers a loss of less than 10 percent from the information theoretical limit. For the MAC, we assume quasi-static fading, and consider cooperation in the low-power regime with the assumption that no CSI is available at the transmitters. We develop cooperation methods based on multiplexed coding in conjunction with rateless codes and find the achievable rates and in particular the minimum energy per bit to achieve a certain outage probability. We then develop practical coding methods using Raptor codes, which performs within 1.1 dB of the performance limit. Finally, we consider a CRC and develop a practical multi-level dirty-paper coding strategy using LDPC codes for channel coding and trellis-coded quantization for source coding. The designed scheme is found to operate within 0.78 dB of the theoretical limit. By developing practical coding strategies for several cooperative communication channels which exhibit performance close to the information theoretic limits, we show that cooperative communications not only provide great benefits in theory, but can possibly promise the same benefits when put into practice. Thus, our work can be considered a useful and necessary step towards the commercial realization of cooperative communications.

Les technologies numériques et du multimédia ont connu de grandes avancées ces dernières années. La chaîne de transmission des images est constituée de plusieurs traitements divers et variés permettant de transmettre un flux de données toujours plus grand avec toujours plus de services à la clé. Nous citons par exemple, la compression, l'augmentation de contenu, la confidentialité, l'intégrité et l'authenticité des images pendant leur transmission. Dans ce contexte, les approches conjointes ont suscité un intérêt certain de la part de la communauté du traitement d'images car elles permettent d'obtenir des systèmes de faible complexité calculatoire pouvant être utilisés dans des applications nécessitant peu de ressources matérielles. La dissimulation de données ou Data Hiding, est l'art de cacher un message dans un support numérique. L'une des branches les plus importantes du data hiding est le tatouage numérique ou watermarking. La marque doit rester présente dans l'image hôte même si celle-ci subit des modifications appelées attaques. La compression d'images a comme objectif de réduire la taille des images stockées et transmises afin d'augmenter la capacité de stockage et de minimiser le temps de transmission. La compression représente une opération incontournable du stockage ou du transfert d'images. Elle est considérée par le data hiding comme une attaque particulièrement destructrice. La norme JPEG2000 est le dernier standard ISO/ITU-T pour le codage des images fixes. Dans cette thèse, nous étudions de manière conjointe la compression avec perte et le data hiding dans le domaine JPEG2000. L'approche conjointe offre de nombreux avantages dont le plus important est que la compression ne constitue plus une attaque vis-à-vis du data hiding. Les contraintes à respecter sont exprimées en termes de compromis à atteindre: compromis entre la quantité d'information insérée (payload), le taux de compression, la distorsion induite par l'insertion du message et la robustesse de la marque dans le cas du tatouage.Nos travaux de recherche ont conduit à l'élaboration de plusieurs schémas conjoints : un schéma conjoint d'insertion de données cachées et deux schémas conjoints de tatouage dans JPEG2000. Tous ces systèmes conjoints reposent sur des stratégies d'insertion informée basées sur la quantification codée par treillis (TCQ). Les propriétés de codage de canal de la TCQ sont exploitées pour pouvoir à la fois quantifier et insérer un message caché (ou une marque) pendant l'étape de quantification de JPEG2000. / Technological advances in the fields of telecommunications and multimedia during the two last decades, derive to create novel image processing services such as copyright protection, data enrichment and information hiding applications. There is a strong need of low complexity applications to perform seveval image processing services within a single system. In this context, the design of joint systems have attracted researchers during the last past years. Data hiding techniques embed an invisible message within a multimedia content by modifying the media data. This process is done in such a way that the hidden data is not perceptible to an observer. Digital watermarking is one type of data hiding. The watermark should be resistant to a variety of manipulations called attacks. The purpose of image compression is to represent images with less data in order to save storage costs or transmission time. Compression is generally unavoidable for transmission or storage purposes and is considered as one of the most destructive attacks by the data hiding. JPEG2000 is the last ISO/ ITU-T standard for still image compression.In this thesis, joint compression and data hiding is investigated in the JPEG2000 framework. Instead of treating data hiding and compression separately, it is interesting and beneficial to look at the joint design of data hiding and compression system. The joint approach have many advantages. The most important thing is that compression is no longer considered as an attack by data hiding.The main constraints that must be considered are trade offs between payload, compression bitrate, distortion induced by the insertion of the hidden data or the watermark and robustness of watermarked images in the watermarking context. We have proposed several joint JPEG2000 compression and data hiding schemes. Two of these joint schemes are watermarking systems. All the embedding strategies proposed in this work are based on Trellis Coded Quantization (TCQ). We exploit the channel coding properties of TCQ to reliably embed data during the quantization stage of the JPEG2000 part 2 codec.