A Survey on Delay-Aware Resource Control for Wireless Systems --- Large Deviation Theory, Stochastic Lyapunov Drift and Distributed Stochastic Learning

In this tutorial paper, a comprehensive survey is given on several major systematic approaches in dealing with delay-aware control problems, namely the equivalent rate constraint approach, the Lyapunov stability drift approach and the approximate Markov Decision Process (MDP) approach using stochastic learning. These approaches essentially embrace most of the existing literature regarding delay-aware resource control in wireless systems. They have their relative pros and cons in terms of performance, complexity and implementation issues. For each of the approaches, the problem setup, the general solution and the design methodology are discussed. Applications of these approaches to delay-aware resource allocation are illustrated with examples in single-hop wireless networks. Furthermore, recent results regarding delay-aware multi-hop routing designs in general multi-hop networks are elaborated. Finally, the delay performance of the various approaches are compared through simulations using an example of the uplink OFDMA systems.Comment: 58 pages, 8 figures; IEEE Transactions on Information Theory, 201

On the utility of network coding in dynamic environments

Many wireless applications, such as ad-hoc networks and sensor networks, require decentralized operation in dynamically varying environments. We consider a distributed randomized network coding approach that enables efficient decentralized operation of multi-source multicast networks. We show that this approach provides substantial benefits over traditional routing methods in dynamically varying environments. We present a set of empirical trials measuring the performance of network coding versus an approximate online Steiner tree routing approach when connections vary dynamically. The results show that network coding achieves superior performance in a significant fraction of our randomly generated network examples. Such dynamic settings represent a substantially broader class of networking problems than previously recognized for which network coding shows promise of significant practical benefits compared to routing

Learning in Real-Time Search: A Unifying Framework

Real-time search methods are suited for tasks in which the agent is interacting with an initially unknown environment in real time. In such simultaneous planning and learning problems, the agent has to select its actions in a limited amount of time, while sensing only a local part of the environment centered at the agents current location. Real-time heuristic search agents select actions using a limited lookahead search and evaluating the frontier states with a heuristic function. Over repeated experiences, they refine heuristic values of states to avoid infinite loops and to converge to better solutions. The wide spread of such settings in autonomous software and hardware agents has led to an explosion of real-time search algorithms over the last two decades. Not only is a potential user confronted with a hodgepodge of algorithms, but he also faces the choice of control parameters they use. In this paper we address both problems. The first contribution is an introduction of a simple three-parameter framework (named LRTS) which extracts the core ideas behind many existing algorithms. We then prove that LRTA*, epsilon-LRTA*, SLA*, and gamma-Trap algorithms are special cases of our framework. Thus, they are unified and extended with additional features. Second, we prove completeness and convergence of any algorithm covered by the LRTS framework. Third, we prove several upper-bounds relating the control parameters and solution quality. Finally, we analyze the influence of the three control parameters empirically in the realistic scalable domains of real-time navigation on initially unknown maps from a commercial role-playing game as well as routing in ad hoc sensor networks

Localized and Configurable Topology Control in Lossy Wireless Sensor Networks

Recent empirical studies revealed that multi-hop wireless networks like wireless sensor networks and 802.11 mesh networks are inherently lossy. This finding introduces important new challenges for topology control. Existing topology control schemes often aim at maintaining network connectivity that cannot guarantee satisfactory path quality and communication performance when underlying links are lossy. In this paper, we present a localized algorithm, called Configurable Topology Control (CTC), that can configure a network topology to different provable quality levels (quantified by worst-case dilation bounds in terms of expected total number of transmisssions) required by applications. Each node running CTC computes its transmission power solely based on the link quality information collected within its local neighborhood and does not assume that the neighbor locations or communication ranges are known. Our simulations based on a realistic radio model of Mica2 motes show that CTC yields configurable communication performance and outperforms existing topology control algorithms that do not account for lossy links

BIGENERIČKI VIŠESTAZNI ALGORITAM ZA USMJERAVANJE ZA BEŽIČNE MREŽE

Routing is the important research issue in the development of Wireless Networks. Multipath routing allows data communication through multiple paths. On the other hand, multi-path routing does not guarantee deterministic transmission. Since one route is available for transferring data from the source node to the destination node. A bigeneric multi-path routing algorithm is planned for significant wireless mesh networks to enhance reliability, also as in impact considering with link failures. The constituted algorithm adopts the modified Dijkstra’s algorithm for searching the shortest route from the gateway to each end node. A virtual trail distinct from the regular trail is introduced to realize trail diffusion and updating. The routes used for data point’s transmission are selected based on their regular trail values, alleviating the delivery of data points through better routes. Link failures are then treated using route maintenance mechanism. This can be accomplished by increase the accuracy through the already visible route measures collected by the routing protocol. Rate adaptation algorithm is designed to compute the best rate for each wireless link. This modified conclusion aims at providing better routing and rate alternatives. Simulation results show that the proposed algorithm outperforms conventional algorithms in terms of packet delivery ratio, end-to-end delay routing operating cost.Usmjeravanje je važan istraživački problem u razvoju bežičnih mreža. Višestazno usmjeravanje omogućuje podatkovnu komunikaciju kroz više puteva. S druge strane, višestruko usmjeravanje ne jamči deterministički prijenos, budući da je jedna ruta dostupna za prijenos podataka iz izvornog čvora do odredišnog čvora. Konstituirani algoritam primjenjuje modificirani algoritam Dijkstra za traženje najkraćeg puta od pristupnika do svakog krajnjeg čvora. Algoritam prilagodbe stope dizajniran je za izračunavanje najbolje brzine za svaku bežičnu vezu. Ovaj modificirani zaključak ima za cilj pružiti bolje usmjeravanje i ocjenjivati alternative. Rezultati simulacije pokazuju da predloženi algoritam nadmašuje konvencionalne algoritme