Pair Of Mobile Nodes Research Articles

A Node Density Control Learning Method for the Internet of Things.

When examining density control learning methods for wireless sensor nodes, control time is often long and power consumption is usually very high. This paper proposes a node density control learning method for wireless sensor nodes and applies it to an environment based on Internet of Things architectures. Firstly, the characteristics of wireless sensors networks and the structure of mobile nodes are analyzed. Combined with the flexibility of wireless sensor networks and the degree of freedom of real-time processing and configuration of field programmable gate array (FPGA) data, a one-step transition probability matrix is introduced. In addition, the probability of arrival of signals between any pair of mobile nodes is also studied and calculated. Finally, the probability of signal connection between mobile nodes is close to 1, approximating the minimum node density at T. We simulate using a fully connected network identifying a worst-case test environment. Detailed experimental results show that our novel proposed method has shorter completion time and lower power consumption than previous attempts. We achieve high node density control as well at close to 90%.

Time synchronization and ranging under unknown positions and velocities

The process to achieve time synchronization and ranging for a network of mobile nodes is raising a concern among researchers, and hence a variety of joint time synchronization and ranging algorithms have been proposed in recent years. However, few of them handle the case of all-node motion under unknown positions and velocities. This study addresses the problem of determining ranging and time synchronization for a group of nodes moving within a local area. First, we examined several models of clock discrepancy and synchronous two-way ranging. Based upon these models, we present a solution for time synchronization with known positions and velocities. Next, we propose a functional model that jointly estimates the clock skew, clock offset, and time of flight in the absence of a priori knowledge for a pair of mobile nodes. Then, we extend this model to a network-wide time synchronization scheme by way of a global least square estimator. We also discuss the advantages and disadvantages of our model compared to the existing algorithms, and we provide some applicable scenarios as well. Finally, we show that the simulation results verify the validity of our analysis.

A Novel Link Reliable Multipath Routing Protocol for MANET

Mobile Ad Hoc networks (MANETs) are self configurable wherein mobile nodes communicate with each other via wireless links. Due to ever-changing topology, frequent link failure and lack of fixed infrastructure, it is difficult to develop and maintain an optimal route between source and destination nodes in MANET. In such a network, it is highly required to construct a link reliable route in order to provide an uninterrupted communication. This paper proposes an ant colony optimization (ACO) based link reliable (LR) ad hoc on demand multipath distance vector (AOMDV) routing (ACO-LR-AOMDV) which is inspired from swarm intelligence especially using collective behavior of natural ants. It establishes and maintains multiple routes between a pair of mobile nodes using simulated pheromone deposited by artificial ants. The optimal path is selected based on hop count and minimum value of the Path-Link Quality Estimator (P-LQE) which have been integrated into the pheromone computation of the path. The efficiency of the proposed protocol is examined using the network simulator NS2.34 and the experimental results show the better performance over the well-known multipath routing protocol AOMDV and ACO-AOMDV in terms of end-to-end delay, routing overhead and packet delivery ratio.

Secret Key Generation Via Localization and Mobility

We consider secret key generation by a pair of mobile nodes utilizing observations of their relative locations in the presence of a mobile eavesdropper. In our proposed algorithm, the legitimate node pair makes noisy observations of the relative locations of each other. Based on these observations, the nodes generate secret key bits via information reconciliation, data compression, and privacy amplification. We characterize a theoretically achievable secret key bit rate in terms of the observation noise variance at the legitimate nodes and the eavesdropper and show that the performance of our algorithm is comparable to the theoretical bounds. We also test our algorithm in a vehicular setting based on observations made using wireless beacon exchange between the legitimate nodes. To achieve this, we used TelosB wireless radios mounted on the sides of the vehicles on local roads and freeways. Note that our approach relies solely on distance reciprocity, and thus, it is not restricted to the use of wireless radios and can be used with other localization systems (e.g., infrared and ultrasound systems) as well. Overall, this study proves, via both information theoretic and practical analysis, that localization information provides a significant additional resource for secret key generation in mobile networks.

Performance Evaluation of FSR, DYMO and LANMAR Routing Protocols

Mobile Ad hoc Network (MANET) is a collection of mobile nodes that are arbitrarily located so that the interconnections between nodes are energetically altering [1]. In MANET mobile nodes forms a temporary network without the use of any existing network infrastructure or centralized administration. A routing procedure is used to find routes between mobile nodes to facilitate communication inside the set of connections. The main goal of such an ad hoc network routing protocol is to establish correct and efficient route between a pair of mobile nodes so that messages delivered within the active route break intermission. Route should be discovered and maintained with a minimum of overhead and bandwidth expenditure. This article presents performance evaluation of three different routing protocols i.e. Fisheye Source Routing (FSR), Landmark Adhoc routing protocol (LANMAR), and Dynamic MANET on Demand Routing Protocol (DYMO) with respect to different nodes. Performance of FSR, LANMAR and DYMO is evaluated based on Throughput and Average end to end delay with and without Black hole Attack.

Discovering periodic patterns of nodal encounters in mobile networks

Routing in Delay Tolerant Networks is very challenging because of frequent disconnections. One cause of disconnection is node movement. Disconnections can be overcome by finding a set of sequential opportunistic encounters between pairs of mobile nodes. These encounters can be used for message forwarding and delivery. In this context, understanding user mobile behaviour is essential to design effective and efficient network protocols. This paper presents a generic methodology to model and find periodic encounter patterns by using the auto-persistence function and detection techniques derived from it. From the studies on four real mobility traces, we are able to detect strong weekly periodic encounter patterns with an accuracy of up to 100%. The experimental results show that periodic encounter patterns in real mobility traces do not last long, e.g., years, because they are interrupted by unexpected events from time to time. Nonetheless our experimental results show that those periodic encounters can still last up to a few months. Furthermore, we show that, for some of the mobility traces, the network formed by periodic encounters forms a small-world structure.

Changing Trends in Modeling Mobility

A phenomenal increase in the number of wireless devices has led to the evolution of several interesting and challenging research problems in opportunistic networks. For example, the random waypoint mobility model, an early, popular effort to model mobility, involves generating random movement patterns. Previous research efforts, however, validate that movement patterns are not random; instead, human mobility is predictable to some extent. Since the performance of a routing protocol in an opportunistic network is greatly improved if the movement patterns of mobile users can be somewhat predicted in advance, several research attempts have been made to understand human mobility. The solutions developed use our understanding of movement patterns to predict the future contact probability for mobile nodes. In this work, we summarize the changing trends in modeling human mobility as random movements to the current research efforts that model human walks in a more predictable manner. Mobility patterns significantly affect the performance of a routing protocol. Thus, the changing trend in modeling mobility has led to several changes in developing routing protocols for opportunistic networks. For example, the simplest opportunistic routing protocol forwards a received packet to a randomly selected neighbor. With predictable mobility, however, routing protocols can use the expected contact information between a pair of mobile nodes in making forwarding decisions. In this work, we also describe the previous and current research efforts in developing routing protocols for opportunistic networks.

Simulation based Performance Comparison of AODV, FSR and ZRP Routing Protocols in MANET

Mobile Ad hoc NETwork (MANET) is a collection of mobile nodes that are arbitrarily located so that the interconnections between nodes are dynamically changing. In MANET mobile nodes forms a temporary network without the use of any existing network infrastructure or centralized administration. A routing protocol is used to find routes between mobile nodes to facilitate communication within the network. The main goal of such an ad hoc network routing protocol is to establish correct and efficient route between a pair of mobile nodes so that messages delivered within the active route timeout interval. Route should be discovered and maintained with a minimum of overhead and bandwidth consumption. This paper presents performance evaluation of three different routing protocols i.e. Ad hoc OnDemand Distance Vector (AODV), Fisheye State Routing (FSR) and Zone Routing Protocol (ZRP) in variable pause times and variable number of nodes. We have used random waypoint mobility model to design the network and performed simulations by using QualNet version 5.0 Simulator [1] from Scalable Networks. Performance of AODV, FSR and ZRP is evaluated based on Average end-to-end delay, Packet delivery ratio, Throughput and Average Jitter.

An overlapping and pipelining data transmission MAC protocol with multiple channels in ad hoc networks

In mobile ad hoc networks (MANETs), the IEEE 802.11 DCF protocol is commonly used at the medium access control (MAC) layer to reduce collision and contention. However, mobile nodes, before send out data, need to wait for other in-process data transmission in the same range to be completed. In this paper, we address this performance degradation problem in the DCF mechanism and propose an overlapping and pipelining data transmission MAC protocol to enhance throughput. The protocol regulates the actions of the neighboring nodes of both the sender and the receiver and enables the utilization of the same channel simultaneously by these neighboring nodes. A multiple sub-channel technique is proposed to avoid the interference problem caused by the control and data signals of different communication mobile node pairs. With the regulated actions and the multiple channel technique, multiple pairs of mobile nodes are provided with the desired feature of utilizing the same data sub-channel simultaneously without interfering with one another. Although the overlapping data transmission technique can increase the number of simultaneous communication pairs, an efficient bandwidth allocation of the control and data sub-channels to maximize utilization is critically important. Therefore, we further propose a bandwidth allocation strategy in which the control signals and data signals are pipelined. Performance simulation results prove the efficiency of the proposed bandwidth allocation strategy with better channel utilization. In addition, the proposed MAC protocol with the bandwidth allocation strategy, combined with the overlapping and pipelining data sub-channel technique, outperforms the IEEE 802.11 DCF in throughput (kB/s) by about 43.76%.

Delay and resource analysis in MANETs in presence of throwboxes

This paper addresses the delay analysis and resource consumption in mobile ad hoc networks (MANETs) equipped with throwboxes. Throwboxes are stationary, wireless devices that act as relays, and that are deployed to increase the connectivity between mobile nodes. Our objective is to quantify the impact of adding throwboxes on the performance of two routing protocols, namely the Multicopy Two-hop Routing protocol and the Epidemic Routing protocol, in the cases where the throwboxes are fully disconnected or mesh connected. To this end, we use a Markovian model where the successive meeting times between any pair of mobile nodes (resp. any mobile node and any throwbox) are represented by a Poisson process with intensity λ (resp. μ ). We derive closed-form expressions for the distribution of the delivery delay of a packet and for the distribution of the total number of copies of a packet that are generated, the latter metric reflecting the overhead induced by the routing protocol. These results are then compared to simulation results. Through a mean-field approach we also provide asymptotic results when the number of nodes (mobile nodes and/or throwboxes) is large.

Statistical estimation of link availability and its impact on routing in wireless ad hoc networks

AbstractIn this paper, an analytical framework is developed and validated via simulation for statistical estimation of the evolution of the separation between a pair of mobile nodes in an ad hoc network. Simulation results demonstrate that path selection based on minimization of the product of the link statistic significantly outperforms minimum‐hop and fixed threshold‐based ‘path‐stability’ schemes. A hierarchical mobility model integrating the dynamic effects of velocity, group movement and geographic scope is used to generalize the results. Another significant result is the performance enhancements hold in large networks irregardless of the assumptions used for statistical estimation. The effect of merging many independent groups appears to restore independent mobility. Finally, results show that at the highest mobility levels, 90% of the longest surviving paths fail within 60 s. None of the strategies approach this optimal value. This important result suggests that optimal predictive mechanisms alone are insufficient to ensure scalable routing in ad hoc networks. Copyright © 2004 John Wiley & Sons, Ltd.