In new wireless systems (such as cognitive radio or millimeter wave networks), users may collaborate so as to get mutual benefit in their communications. For example, in cognitive radio networks each secondary user can assist a primary user in its communication and in exchange, get access to the primary user channel. Thus, each group of secondary users assisting the same primary user forms a coalition. Within each coalition, sequential relaying is employed, and a relay ordering algorithm is used to make use of the relays in an efficient manner. It is required then to find the optimal sets of secondary users assisting each primary user such that the sum of their rates is maximized. Another example is millimeter wave systems, for which the channels suffer from considerable degradation in the channel quality when the signal is Non Line of Sight (NLOS) between the source and the destination. Multihop relaying is thus anticipated to improve the communication between a source and its destination. This is achieved by transmitting the signal to a sequence of relays in which a Line of Sight (LOS) signal exists between two nodes along the path, or more generally when the signal is better than the transmitted signal directly from the source to the destination. Consider a millimeter wave network composed of multiple source-destination pairs and a set of deployed relays. Then, the problem of multi hop relaying can be seen as a cooperative network formation game in which each relay chooses which source-destination pair to assist in order to improve the end-to-end performance, that is, the multi hop delay between the source and the destination. In this talk we present a uniform model of such situations using the coalition game framework of game theory and discuss some possible algorithmic solution and their performance.
Corinne Touati is a research scientist at Inria Rhône Alpes since 2006. She has received her Ph.D. degree from the University of Nice Sophia Antipolis in 2003 and her engineering degree in information and communication technology from Telecom SudParis in 2000. She has been a post-doctoral fellow at the University of Tsukuba from 2003 to 2006. Her research focuses on strategic interactions in distributed systems with emphasis on wireless systems, using game theoretic models, with the goal of developing distributed solutions for system optimization and control. Her recent work involves studying situations of competitive approaches, collusion and fair sharing, assessing their relative performance and developing distributed algorithmic solutions.