Feedback Allocation For OFDMA Systems With Slow Frequency-domain Scheduling

We study the problem of allocating limited feedback resources across multiple users in an orthogonal-frequency-division-multiple-access downlink system with slow frequency-domain scheduling. Many flavors of slow frequency-domain scheduling (e.g., persistent scheduling, semi-persistent scheduling), that adapt user-sub-band assignments on a slower time-scale, are being considered in standards such as 3GPP Long-Term Evolution. In this paper, we develop a feedback allocation algorithm that operates in conjunction with any arbitrary slow frequency-domain scheduler with the goal of improving the throughput of the system. Given a user-sub-band assignment chosen by the scheduler, the feedback allocation algorithm involves solving a weighted sum-rate maximization at each (slow) scheduling instant. We first develop an optimal dynamic-programming-based algorithm to solve the feedback allocation problem with pseudo-polynomial complexity in the number of users and in the total feedback bit budget. We then propose two approximation algorithms with complexity further reduced, for scenarios where the problem exhibits additional structure.Comment: Accepted to IEEE Transactions on Signal Processin

Coping with dynamic membership, selfishness, and incomplete information: applications of probabilistic analysis and game theory

textThe emergence of large scale distributed computing networks has given increased prominence to a number of algorithmic concerns, including the need to handle dynamic membership, selfishness, and incomplete information. In this document, we outline our explorations into these algorithmic issues. We first present our results on the analysis of a graph-based coupon collecvi tor process related to load balancing for networks with dynamic membership. In addition to extending the study of the coupon collector process, our results imply load balancing properties of certain distributed hash tables. Second, we detail our results on worst case payoffs when playing buyersupplier games, against many selfish, collaborating opponents. We study optimization over the set of core vectors. We show both positive and negative results on optimizing over the cores of such games. Furthermore, we introduce and study the concept of focus point price, which answers the question: If we are constrained to play in equilibrium, how much can we lose by playing the wrong equilibrium? Finally, we present our analysis of a revenue management problem with incomplete information, the online weighted transversal matroid matching problem. In specific, we present an algorithm that delivers expected revenue within a constant of optimal in the online setting. Our results use a novel algorithm to generalize several results known for special cases of transversal matroids.Computer Science

Studies on chimeric plants of the grapevine (Vitis vinifera L., cultivar Bolgar)

Chimeric grapevines have been established in the cultivar Bolgar as a result of the natural mutation process. Part of these grapevines is diploid, while the other part of the same plants is a di-tetraploid periclinal chimera of the 2-4 type. Yield and quality of grapes are the lowest in the cases when the fruit-bearing shoots are formed on the chimeric part.Étude sur les plantes chimériques de la vigne (Vitis vinifera L., variété Bolgar)Chez la variété Bolgar on a découvert des vignes chimériques - résultat de mutations naturelles. Une partie de ces vignes est diploide, une autre représente une chimère périclinale di-tétraploide du type 2-4. Quand les sections fruitières sont formées sur la partie chimérique, les caractéristiques du rendement et de la qualité du raisin sont les plus basses