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With the technology development, more and more transactions or activities are conducted via networks. Along with electronic technology penetrating every where in the world, networks need face the new problem which was not predicted when networks were firstly designed, the malicious attack. The existing malicious activity or malicious person forces to redesign a much safer network. The security problem in multi hop wireless networks is more severe than that in wired networks since its transmission media is the unprotected air, which makes wireless network easier to be attacked. In this paper, we show how to increase the effective throughput via carefully choosing the multi-path routing for given source and destination nodes under attack. We model the problem as a two-player game and theoretically prove that the corresponding routing protocols can achieve an effective network throughput (with packets which are not attacked) within a constant factor of the optimum in the worst case. Our theoretic results are confirmed by extensive simulations studies. [ABSTRACT FROM AUTHOR]

Providing Quality of Service (QoS) is a major challenge in wireless networks. In this paper we propose a distributed call admission control protocol (DCAC) to do both bandwidth and delay guaranteed call admission for multihop wireless mesh backbone networks, by exploiting the multi-channel multi-radio (mc-mr) feature. We propose a novel routing metric for route setup, and present an efficient distributed algorithm for link reservation that satisfies the required bandwidth and reduces the delay by a local scheduling that minimizes one hop delay. To the best of our knowledge, this is the first distributed protocol that embeds mc-mr feature in Time Division Medium Access (TDMA) to do QoS call admission in wireless backbone networks. Extensive simulation studies show that our protocol significantly improves network performance on supporting QoS sessions compared with some widely used protocols. [ABSTRACT FROM AUTHOR]

Assume that n wireless nodes are uniformly randomly deployed in a square region with side-length a and all nodes have the uniform transmission range r and uniform interference range R > r. We further assume that each wireless node can transmit (or receive) at W bits/second over a common wireless channel. For each node vi, we randomly and independently pick k - 1 points pi,j (1 ≤ j ≤ k - 1) from the square, and then multicast data to the nearest node for each Pi,j. We derive matching asymptotic upper bounds and lower bounds on multicast capacity of random wireless networks. Under protocol interference model, when a²/r² = O(n/log(n)), we show that the total multicast capacity is Θ (√n/log n · (W/√k)) when k = O(n/log n); the total multicast capacity is Θ; (W) when k = Ω(n/ log n). We also study the capacity of group-multicast for wireless networks where for each source node, we randomly select k - 1 groups of nodes as receivers and the nodes in each group are within a constant hops from the group leader. The same asymptotic upper bounds and lower bounds still hold. We also extend our capacity bounds to d-dimensional networks. [ABSTRACT FROM AUTHOR]

Abstract-We study efficient interference-aware joint routing and TDMA link scheduling for a multihop wireless network to maximize its throughput. Efficient link scheduling can greatly reduce the interference effect of close-by transmissions. Unlike the previous studies that often assume a unit disk graph (UDG) model, we assume that different terminals could have different transmission ranges and different interference ranges. In our model, it is also possible that a communication link may not exist due to barriers or is not used by a predetermined routing protocol, while the transmission of a node always result interference to all nonintended receivers within its interference range. Using a mathematical formulation, we develop interference-aware joint routing and synchronized TDMA link schedulings that optimize the networking throughput subject to various constraints. Our linear programming formulation will find a flow routing whose achieved throughput is at least a constant fraction of the optimum, and the achieved fairness is also a constant fraction of the requirement. Then, by assuming known link capacities and link traffic loads, we study link scheduling under the request-to-send and clear-to-send (RTS/CTS) interference model and the protocol interference model (PrIM) with fixed transmission power. For both models, we present both efficient centralized and distributed algorithms that use timeslots within a constant factor of the optimum. We also present efficient distributed algorithms whose performances are still comparable with optimum, but with much less communications. We prove that the timeslots needed by our faster distributed algorithms are only at most O(iniii(logn, Iog ψ)) for RTS/ CTS interference model and PrIM. Our theoretical results are corroborated by extensive simulation studies. [ABSTRACT FROM AUTHOR]

Abstract  In this paper, we address the problem of gateway placement for throughput optimization in multi-hop wireless mesh networks. Assume that each mesh node in the mesh network has a traffic demand. Given the number of gateways to be deployed (denoted by k) and the interference model in the network, we study where to place exactly k gateways in the mesh network such that the total throughput is maximized while it also ensures a certain fairness among all mesh nodes. We propose a novel grid-based gateway deployment method using a cross-layer throughput optimization, and prove that the achieved throughput by our method is a constant times of the optimal. Simulation results demonstrate that our method can effectively exploit the available resources and perform much better than random and fixed deployment methods. In addition, the proposed method can also be extended to work with multi-channel and multi-radio mesh networks under different interference models. [ABSTRACT FROM AUTHOR]

Consider a wireless sensor network consisting of n wireless sensors randomly distributed in a two-dimensional plane. In this paper, we show that with high probability we can locally find a path for any pair of sensors such that the length of the path is no more than a constant factor of the minimum. By assuming each sensor knows its position, our new routing method decides where to forward the message purely based on the position of current node, its neighbours, and the positions of the source and the target. Our method is based on a novel structure called localized Delaunay triangulation and a geometric routing method that guarantees that the distance travelled by the packets is no more than a small constant factor of the minimum when the Delaunay triangulation of sensor nodes are known. Our experiments show that the delivery rates of existing localized routing protocols are increased when localized Delaunay triangulation is used instead of several previously proposed topologies, and our localized routing protocol based on Delaunay triangulation works well in practice. We also conducted extensive simulations of another localized routing protocol, face routing. The path found by this protocol is also reasonably good compared with previous one although it cannot guarantee a constant approximation on the length of the path travelled theoretically. Copyright © 2006 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The article discusses various reports published within the issue including one on opportunistic routing, the construction of virtual backbone with wireless ad-hoc network constraints, and wireless ad-hoc network connectivity.