Truth-Telling Mechanism for Two-Way Relay Selection for Secrecy Communications With Energy-Harvesting Revenue

This paper brings the novel idea of paying the utility to the winning agents in terms of some physical entity in cooperative communications. Our setting is a secret two-way communication channel where two transmitters exchange information in the presence of an eavesdropper. The relays are selected from a set of interested parties, such that the secrecy sum rate is maximized. In return, the selected relay nodes' energy harvesting requirements will be fulfilled up to a certain threshold through their own payoff so that they have the natural incentive to be selected and involved in the communication. However, relays may exaggerate their private information in order to improve their chance to be selected. Our objective is to develop a mechanism for relay selection that enforces them to reveal the truth since otherwise they may be penalized. We also propose a joint cooperative relay beamforming and transmit power optimization scheme based on an alternating optimization approach. Note that the problem is highly non-convex, since the objective function appears as a product of three correlated Rayleigh quotients. While a common practice in the existing literature is to optimize the relay beamforming vector for given transmit power via rank relaxation, we propose a second-order cone programming-based approach in this paper, which requires a significantly lower computational task. The performance of the incentive control mechanism and the optimization algorithm has bee

Cooperative Transmitter-Receiver Arrayed Communications

This thesis is concerned with array processing for wireless communications. In particular, cooperation between the transmitter and receiver or between systems is exploited to further improve the system performance. Based on this idea, three technical chapters are presented in this thesis. Initially in Chapter 1, an introduction including array processing, multiple-input multiple-output (MIMO) communication systems and the background of cognitive radio is presented. In Chapter 2, a novel approach for estimating the direction-of-departure (DOD) is proposed using the cooperative beamforming. This proposed approach is featured by its simplicity (beam rotation at the transmitter) and effectiveness (illustrated in terms of channel capacity). Chapter 3 is concerned with integration of spatio-temporal (ST) processing into an antenna array transmitter, given a joint transmitter-receiver system with ST processing at the receiver but spatial-only processing at the transmitter. The transmit ST processing further improves the system performance in convergence, mean-square error (MSE) and bit error rate (BER). In Chapter 4, a basic system structure for radio coexistence problem is proposed based on the concept of MIMO cognitive radio. Cooperation between the licensed radio and the cognitive radio is exploited. Optimisation of the sum channel capacity is considered as the criterion and it is solved using a multivariable water-filling algorithm. Finally, Chapter 5 concludes this thesis and gives suggestions for future work

Framework for media oriented transport systems

Dissertação de mestrado integrado em Engenharia Electrónica Industrial e ComputadoresThe natural evolution of embedded systems resulted in a faster execution of tasks, increased possibility for including additional features, allied to lower power consumption and benefiting from ever-growing rates of integration as far as silicon is concerned. The automotive industry is not an exception with regards to the integration of technology for a vast arrays of applications in systems which vary from entertainment of infotainment to systems related to vehicle safety and stability such as driver assists. The existence of diverse independent systems in modern cars, combined with the necessity of centralizing the user interface, simplifying the operation of the system and minimizing the user’s intervention, help to promote the comfort and reduce the likelihood of distractions taking place while driving. Modern communication oriented network standards, e.g. MOST or FlexRay, enable information compatibility when exchanged between systems communicating over different protocols. Moreover, the coexistence of packet, control and timesensitive information are ensured within timing requirements, providing a reliable QoS (Quality of Service) and by making use of a single physical transmission mean. Synchronized multimedia data (e.g. synchronized video and audio transmission) are example of this kind of (time-sensitive) information. This dissertation proposes a framework for design and development of network distributed applications in the field of automotive infotainment, compliant with the industry standards and using FPGA technology in order to ensure the system requirements satisfaction and promote IP Core re-utilization.A evolução natural dos sistemas embebidos traduziu-se numa maior rapidez na execução de tarefas, a possibilidade de incluir mais funcionalidades, aliado a menores consumos energéticos e beneficiando de crescentes e elevadas taxas de integração ao nível de silício. A indústria automóvel não é excepção no que diz respeito à integração de tecnologia para as mais variadas aplicações, com ou sem tolerância à falha, em sistemas que vão desde entretenimento ou infotainment a sistemas relacionados com a estabilidade e segurança do veículo, como é exemplo as driver assists. Existem de vários sistemas independentes nos modernos veículos automóveis. Estes, combinados com a necessidade de centralização ao nível de interface com o utilizador, tornam imperativa a simplicidade da operação. Para tal, requerem a minimizaccão da intervenção do utilizador, promovendo o conforto e diminuindo a probabilidade de desconcentração durante o exercício de condução. Os mais modernos standards de redes de comunicação como é exemplo o MOST ou o FlexRay, permitem a compatibilidade de informação trocada entre sistemas que comunicam através de distintos protocolos de comunicação. Para além disso, ainda garantem a coexistência de informação de controlo, informação do entretenimento e informação do tipo time-sensitive, onde os requisitos de temporização devem ser assegurados, mantendo uma qualidade de serviço fiàvel e fazendo uso de um único meio físico de transmissão. São exemplos deste tipo de informação, dados síncronos do tipo multimédia (e.g. streaming de àudio e vídeo de forma sincronizada). Pretende-se desenvolver uma framework para desenvolvimento de aplicações de rede distribuídas, do tipo infotainment e que beneficia a aplicação de tecnologias como FPGA, no offloading de computação para este dispositivo, como meio de garantir a satisfação dos requisitos, e promover a reutilização deste tipo de sistemas, mantendo o elevado desempenho na troca de dados e promovendo a portabilidade e a modularidade