چكيده به لاتين
In this thesis, first we propose a new approach for mathematical multiple criteria decision making (MCDM) methods using information theoretic measures, entropy and divergence. Using the concept of entropy, we determine the impact of each criterion in decision making process. The Shannon's entropy has been previously employed for this purpose. In this thesis we use Renyi's entropy and the concept of information potential of each criterion for weight assessment. Next, we introduce divergence as new separation measure for MCDM methods. The results indicate that the new measure outperforms the conventional Euclidean distance measure. These techniques employed in MCDM methods are new and may be of independent interest. Further more, we consider a wireless cooperative network with a base station (central unit) and many subscribers (users) in which the subscribers have the ability to relay information for each other to improve the overall network performance. In future wireless communication networks where subscribers are intellectual and pursue various objectives, they will not help relay information for others. This means that the viability of cooperative communication networks largely depends on the willingness of users to help. The reputation based schemes solved this problem by stimulating the users to cooperate with others. Besides, the average achievable rate at the destination node in a relay based network highly depends on the relay node location. Therefore, for a relay selection scheme, the choices of relay location, and the reputation of each user as well as signal-to-noise ratio, which is the main criterion for relay selection schemes, are important selection parameters. This thesis proposes a novel multiple criteria relay selection scheme with a low implementation complexity. The proposed scheme incorporates reputation, SNR and location of the users in a highest-level design that not only selects the best relay node for each source-destination pair, but also assigns weight efficiently for each criterion. A simple and efficient optimization tool based on multiple criteria decision making method (MCDM) is employed to solve our formulated problem. Finally, the numerical results are provided to illustrate the comparisons between different typical experiments. To best of our knowledge, no prior work has studied the process of relay selection from this point of view.
