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Although several analytical models have been proposed for wireless sensor networks (WSNs) with different capabilities, very few of them consider the effect of general service distribution as well as design constraints on network performance. This paper presents a new analytical model to compute message latency in a WSN with loop-free Bellman Ford routing strategy. The model considers limited buffer size for each node using M/G/1/k queuing system. Also, contention probability and resource utilization are suitably modeled. The results obtained from simulation experiments confirm that the model exhibits a high degree of accuracy for various network configurations. © 2009 IEEE  

Motivated by applications of sensor networks, there has been growing interest in monitoring large scale distributed systems. In these applications, we usually wish to monitor a global system condition defined as a function of local network elements parameters. In this paper, we study Reactive Monitoring in sensor networks, which has the benefit of operating in a decentralized manner. Our primary concern in adopting such a monitoring paradigm is reducing the communication cost which is the dominant factor of energy drain in wireless sensor networks. In this study, we address the reactive aggregate monitoring problem by casting the underlying threshold assignment as an optimization problem.... 

Wireless sensor networks (WSNs) are a new technology, foreseen to be used increasingly in the near future, and security is an important issue for them. However because of the nodes resource limitations, other schemes proposed for securing general ad hoc networks, are not appropriate for WSNs. Usually some nodes act maliciously and they are able to do different kinds of DoS attacks. In order to make the network more secure, malicious nodes should be isolated from the network. In this paper, we model the interaction of nodes in WSN and intrusion detection system (IDS) as a Bayesian game formulation and use this idea to make a secure routing protocol. By this approach nodes are motivated to act... 

Although many Medium Access Control (MAC) protocols have been specifically designed for WSNs where energy awareness is an essential consideration, only a few of them have considered the presence of mobile nodes or dynamic network topology in their protocols. However, they have usually considered occasional mobility, in which a few number of nodes may start moving at very low speeds and then remained immobile for a long period of time. In this paper, we propose a modified version of LMAC as Mobile-LMAC (MLMAC) to improve its performance in the scenarios include continuous mobility. The protocol is compared to SMAC and LMAC by simulation. The results show that the proposed MLMAC protocol has... 

Considering a multihop cellular system with one relay per sector, an effective modeling for the joint base-station/relay assignment, rate allocation, and routing scheme is proposed and formulated under a single problem for the downlink. This problem is then formulated as a multidimensional multichoice knapsack problem (MMKP) to maximize the total achieved throughput in the network. The well-known MMKP algorithm based on Lagrange multipliers is modified, which results in a near-optimal solution with a linear complexity. The notion of the infeasibility factor is also introduced to adjust the transmit power of base stations and relays adaptively. To reduce the complexity, and in order to... 

The mobility pattern of users is one of the distinct features of vehicular ad hoc networks (VANETs) compared with other types of mobile ad hoc networks (MANETs). This is due to the higher speed and the roadmap-restricted movement of vehicles. In this paper, we propose a new analytical mobility model for VANETs based on product-form queueing networks. In this model, we map the topology of the streets and the behavior of vehicles at both intersections and different parts of the streets onto different parameters of a BCMP1 open queueing network comprising M/G/nodes. This model represents a sparse situation for VANETs. To include the effect of dense situation on the mobility model, we modify the... 

Chemical reactions are a prominent feature of molecular communication systems, with no direct parallels in wireless communications. While chemical reactions may be used inside the transmitter nodes, receiver nodes, or the communication medium, we focus on its utility in the medium in this paper. Such chemical reactions can be used to perform computation over the medium as molecules diffuse and react with each other (physical-layer computation). We propose the use of chemical reactions for the following purposes: 1) to reduce signal-dependent observation noise of receivers by reducing the signal density; 2) to realize molecular physical-layer network coding (PNC) by performing the natural XOR... 

Wireless body area networks (WBANs) are characterized by short-range wireless communication between inherently resource-limited sensors that operate in the vicinity of the human body for recording certain physiological signals. One of the main limitations of WBANs is in terms of their available power. Since the nodes are typically battery-driven, an efficient power transmission is essential to guarantee long-lasting communications among nodes without the need for frequent battery replacement or charging. In this study, aiming to improve the WBAN performance, we first investigate the power allocation problem by choosing the ergodic capacity and the outage probability as the desired metrics.... 

Mobile Ad hoc Networks (MANETs) are based on the assumption of that all participants in the network cooperate and forward packets towards the destinations. However, due to the limited nature of the nodes' resources, a node may decide not to cooperate to save its resources while still using the network. Such behavior of some nodes may degrade the whole network performance. To cope with such a situation, we propose a Stable path, Low overhead, Truthful, and Cost efficient (SLTC) routing protocol which stimulates nodes to cooperate. SLTC utilizes the game theoretic notion of mechanism design. To the best of our knowledge, SLTC is the first protocol attaining the message complexity of O(nd),... 

Mobile ad hoc networks have different characteristics from wired networks. There are new challenges related to security issues that need to be addressed. In this paper, first, critical nodes and authentication in mobile ad hoc networks are discussed. Then, a monitoring nodes selection method with high battery power in these networks is presented. We propose a three-phase detection scheme. In the first phase, unauthorized nodes and in the second phase, malicious nodes are detected. Finally in the third phase, nodes with the largest battery power as monitoring nodes are considered. In the first and the second phases, detection scheme uses non-interactive zero knowledge technique in order to... 

Flooding and its variants are the simplest and most widely used broadcasting methods. Therefore, analysis of its performance in an ad-hoc environment using realistic assumptions is an important research topic. In this article, deploying a rigorous theoretic analysis, an upper bound on the performance of probabilistic flooding running over CSMA as a real and suitable MAC layer protocol for broadcasting scenarios is derived in a static multi-hop ad-hoc network in saturated condition. This model reveals the relation between network parameters and the performance of flooding and thus, helps the designer to have a better understanding of the effect of different design parameters. Using this... 

Recently, distributed space-time coding over half duplex wireless relay networks has been proposed to achieve higher diversity at the receiver. The use of orthogonal and quasi-orthogonal designs in such relay networks has the advantage of providing maximum diversity at a low decoding complexity. However, similar to their originating space-time codes, these designs are restricted in terms of rate and number of relays. In order to alleviate such restrictions, we propose an extension of group-coherent codes (GCCs) to wireless relay networks. As will be shown, with a very limited amount of feedback from receiver to the relays, it is possible to achieve a distributed code that is applicable for... 

In this paper, we propose a new method of signaling based on Frequency Shifted Reference (FSR) for Ultra-wideband (UWB) communication system in which the channel estimation is not required in the decoder. This signaling is more like orthogonal signaling of frequency shift keying (FSK), and has its advantage of non-coherent detection; so as a result, one of the major drawbacks of previously introduced FSR-UWB system can be eliminated. It is shown that in binary signaling the proposed method achieves similar performance as conventional Transmitted Reference UWB (TR-UWB) systems without any rate loss. Also, it is demonstrated that the proposed method outperforms the conventional FSR-UWB system... 

In this paper we examine the transmission of two types of ultra-wideband (UWB) signals, multiband orthogonal frequency division multiplexing (MB-OFDM) and impulse radio ultra-wideband (IR-UWB), over single mode fiber at 1550 nm. In order to investigate the impact of optical components such as laser diode, external modulator and single mode fiber on UWB signals, we develop mathematical models for these components. These models are experimentally verified and corresponding numerical parameter values are obtained by experiment. Using these models we discuss the transmission of two types of UWB signals over single mode fiber. A new figure of merit namely distortion factor is defined. Using this... 

Overlay multicast has gained much attention in recent years as an alternative method to network layer multicast, especially for mobile ad hoc networks (MANETs). In this paper, we propose a new overlay multicast protocol to achieve simplicity of deployment, rapid adaptation of overlay structure when nodes move, and reduced delay. In our algorithm, to join or leave a multicast group, it is only sufficient for a member node to inform its first upstream member node. This updates the tree structure more rapidly when nodes move. In addition, join and leave delays are reduced and this makes the protocol suitable for multimedia multicasting in MANETs. Simulation results compared to that of ODMRP and... 

In New applications of Mobile Ad hoc Networks (MANETs), nodes may decide not to cooperate in routing protocols in order to save their limited resources while still using the network to relay their own traffic. Exhibiting such a selfish behavior by even a few nodes may degrade network performance and other cooperating nodes may find themselves unfairly loaded. To cope with such a situation, we propose a Stable path, Low overhead, Truthful, and Cost efficient (SLTC) routing protocol which stimulates nodes to cooperate and act truthfully by utilizing the game theoretic notion of mechanism design. To the best of our knowledge, SLTC is the first protocol attaining the message complexity of O(nd),... 

combination of smart antenna techniques and OFDM could be considered as a promising solution for improving the performance and enhancing the data rates of next generation wireless communication systems operating in frequency selective fading environments. There are different design parameters which could affect the application of adaptive arrays in OFDM-based systems. Various beam-forming methods in frequency or time domain, different array architectures and various number of array elements are important factors which are able to change the performance and complexity of the system. These parameters may show different effects in different channel conditions. In this paper we implemented a new... 

In this paper, a hierarchical routing protocol for wireless sensor networks is introduced that aims at reducing the energy imbalance among sensor nodes by integrating the distance of the nodes from the base station into clustering policies. Moreover, the proposed routing protocol does not need any centralized support from a certain node which is at odds with aiming to establish a scalable routing protocol. Mobility management is a salient feature of this protocol that guarantees reliable communications between mobile and static nodes. A simulator was developed in the MATLAB environment to evaluate the performance of this protocol. Simulations on two different network configurations are used... 

Energy consumption is one of the most important design criteria in Wireless Sensor Networks. Sensor nodes are expected to be battery-equipped. Due to their working environments, recharging or replacing batteries for each node is difficult and uneconomical. So prolonging the service lifetime of sensor nodes is a critical issue. The MAC protocol for WSNs plays a very important role in the control of energy consumption. Many of proposed MAC protocols attempt only to prolong the network lifetime for energy-efficiency. In this paper, we are going to reduce end-to-end latency in addition to extending the network lifetime. To reach this purpose, we propose a new adaptively ProLong MAC protocol... 

There are applications where important and critical data should be sent to all nodes in a wireless Ad-hoc network. Flooding and its variants are typically used to achieve this target. Network coding can also be used for broadcasting in such an environment. Energy consumption in the network, coverage and total delay are all important parameters that should be considered when an algorithm is evaluated. In this article, a reliable and energy efficient single source broadcasting algorithm is proposed based on network coding. This algorithm guarantees the delivery of desired messages to all network nodes, consumes less energy compared and reduces the total delay compared to other algorithms. This...