The effect of traffic load on using XCAST based routing protocol in wireless ad hoc networks

Tree-based routing protocols in low-rate wireless mesh networks usually have the detour problem in return for the no route discovery overhead. In this paper, we propose a novel algorithm, named Incremental Path Reduction (IPR), which incrementally shortens inefficient detoured path as more data packets are delivered. In IPR, data packets are delivered along the tree route in use by using 1-hop broadcast, enabling neighbor nodes to learn about the data packets' hop count. Using the hop counts, each node estimates their residual hop count to destination. As a result, each forwarder selects next hop node that has small residual hop count. In this way, IPR incrementally shortens the detoured route as more data packets are delivered. To verify our algorithm, we applied IPR to the representative tree routing protocols, and evaluated the path stretch and packet delivery ratio as well as control packet overhead. Simulation results show that IPR significantly enhances the overall routing metrics for any types of tree-based routing protocols.

Vehicular ad-hoc network VANET is an important technology for future development of intelligent transportation systems. Due to the highly-dynamic nature of vehicular nodes, network topology changes very frequently which complicate the routing of data packets. A number of routing protocols have been developed by various researchers. Hop count is a key parameter in evaluating the performance of a routing protocol. Number of hops required in directional routing protocols is more in comparison to other routing protocols. For a city vehicular traffic scenario we propose an improved direction-based location aided routing D-LAR protocol that we call distance and direction-based location aided routing DD-LAR protocol. A mathematical model for DD-LAR protocol has been developed to examine its performance on path duration and hop count metric. Simulations have been done in MATLAB and from the results, it can be seen that DD-LAR routing protocol shows significant performance improvement over D-LAR and LAR in terms of reducing the hop count and maximising the path duration.

The traffic load has grown significantly in recent years, which could pose a threat to the service safety of existing bridges. Thus, evaluating the actual traffic load effects on bridges using actual traffic data is an urgent task. This study presents a framework for extrapolating maximum dynamic traffic load effects on long-span bridges using site-specific traffic monitoring data. The framework involves traffic-bridge interaction analysis and probabilistic modeling of extreme values. The weigh-in-motion measurements of a heavy-duty highway were utilized to simulate stochastic traffic loads. Case studies of two long-span cable-supported bridges based on weigh-in-motion measurements were undertaken to demonstrate the effectiveness of the proposed framework. It was concluded that Rice’s level-crossing approach can capture both the dynamic and probabilistic characteristics of traffic load effects, and thus provides a reasonable extrapolation. The amplification factors for the cable-stayed bridge and the suspension bridge are 5.9% and 3.6%, respectively. For a longer-span bridge, the dynamic effect for extrapolation is weaker, but the effect of traffic volume growth seems more significant.

With the steadily growing of global transportation market, the traffic load has increased dramatically over the past decades, which may develop into a risk source for existing bridges. The simultaneous presence of heavy trucks that are random in nature governs the serviceability limit for large bridges. This study investigated probabilistic traffic load effects on large bridges under actual heavy traffic load. Initially, critical stochastic traffic loading scenarios were simulated based on millions of traffic monitoring data in a highway bridge in China. A methodology of extrapolating maximum traffic load effects was presented based on the level-crossing theory. The effectiveness of the proposed method was demonstrated by probabilistic deflection investigation of a suspension bridge. Influence of traffic density variation and overloading control on the maximum deflection was investigated as recommendations for designers and managers. The numerical results show that the congested traffic mostly governs the critical traffic load effects on large bridges. Traffic growth results in higher maximum deformations and probabilities of failure of the bridge in its lifetime. Since the critical loading scenario contains multi-types of overloaded trucks, an effective overloading control measure has a remarkable influence on the lifetime maximum deflection. The stochastic traffic model and corresponding computational framework is expected to be developed to more types of bridges.

In this paper, we consider the problem of unbalanced energy consumption for nodes in wireless sensor networks (WSN). Current routing protocols divide the network into clusters and route data packets by electing cluster heads, but ineffective network energy utilization leads to the death of nodes very soon. We show that the behavior of sensor networks becomes very unstable once the first node dies. We propose NSEEAR - network stability enhancement by energy aware routing, an adaptive routing protocol which leads to a better energy utilization of the network to prolong its stability period (the time interval before the death of the first node) and the significant network lifetime (the time interval before half of the network is dead) which is crucial for many sensing applications in which the feedback from the network should be reliable. NSEEAR organizes the network into concentric tiers around the base station and routes aggregated data packets by forwarding them from one tier to another in the direction of the base station. Relaying nodes are elected by considering their distance from the transmitting node and the base station, as well as their residual energy. We evaluate NSEEAR through analysis and simulations and show that NSEEAR results in much longer stability periods compared to those obtained by the current clustering protocols.

For the past ten years, heterogeneous networks wired and wireless had tended to integrate seamlessly, offering effective and reliable service for medical operations. One of the problems encountered by network practitioners is the seamless integration of network components into healthcare delivery. As a multiplexing hospital model, the implementation certainly presents some challenges. The major technical and performance issues involve are as following. The operating parameters should keep aligned to the Quality of Service (QoS) requirement throughout simulation. Bandwidth utilisation of wireless networking is a challenging issue for real-time multimedia transmission. IEEE 802.11 provides relatively lower data rate than wired networks, thus the developer tends to adopt a more compromised solution: either reduce the file size or compress the image packets. Communication performance that varies constantly with the impact of signal strength, traffic load and interference. As stated radio signal senses as a curve and attenuates greatly while metallic object and microwave exist within the active range. To ensure devices do not interfere with other electronic equipments (e.g. heart monitors), assert wireless spectrum has to be managed appropriately. This research paper aims to develop a generic hospital network scenarios using Wireless Local Area Network (WLAN) over OPNET Simulation, to evaluate the performance of the integrated network scenario for Intensive Care Units (ICU). This research makes use of computer simulation and discusses various aspects of the network design, so as to discover the performance behaviour pertaining to effect of traffic type, traffic load and network size. In the ICU scenario, the performance of video conference degrades with network size, thus, a QoS-enabled device is recommended to reduce the packet delay and data loss. IEEE 802.11a suits in hospital environment because it mitigates interference on the 2.4GHz band where most wireless devices operate. Experiment examines the effect of signal strength in WLAN. It is convinced that -88dBm is the best signal strength threshold. Although 802.11a generates slightly lower throughput than 802.11g, this issues can be addressed by placing more APs in the service area. It is convinced that 802.11a suits the hospital environments, because it mitigates interference on the popular 2.4GHz band where most wireless devices operate. It is important for medical devices which require future upgrade and Bluetooth deployment.

Based on the bridge health monitoring data, the traffic-load effect model for arch bridge suspender was set up using direct statistical method. Firstly, the Bridge Health Monitoring System (BSHM) set up on the Ebian Dadu River Bridge in Sichuan province to obtain daily traffic-load effect of suspenders was introduced. Secondly, the section distribution of suspender traffic-load effect was researched by statistical approach using monitoring data. Finally, the probability distribution of maximum traffic-load effect during design period was given. The statistical result shows that the section distribution of suspender traffic-load effect follows lognormal distribution and the probability distribution of maximum traffic-load effect during design period follows generalized extreme-value distribution. The traffic-load effect model of suspender was different with the design code given which may underestimates the real load effect level. It's the first time in China to determine the traffic-load effect probability model for arch bridge suspenders based on actual acquired monitoring data using statistical and probabilistic approach.

The performance of mobile ad-hoc networks (MANET) is related to the efficiency of the routing protocols in adapting to frequently changing network topology and link status. This paper addresses the issue by comparing the relative performance of three key ad-hoc routing protocols: destination-sequenced distance vector (DSDV), ad-hoc on-demand distance vector (AODV) and optimized link state routing (OLSR). The protocols are tested based on two scenarios, namely, tactical networks for ships and sensor-based network nodes. Four performance metrics were measured by varying the maximum speed of mobile hosts, network size and traffic load, to assess the routing capability and protocol efficiency. The simulation results indicate that AODV performs better than OSLR and DSDV in the first scenario. Although OLSR also performed relatively well, the associated high routing overhead is the dominant reason for not choosing it. On the other hand, OLSR emerged as the protocol of choice for sensor networks, where the high routing overhead is counteracted by consistently better performance in all other metrics. Due to the slow evolution of the sensor network topology, OLSR performed satisfactorily for best effort traffic but needed subtle adjustments to balance between latency and bandwidth to meet the requirements of delay-sensitive applications

In this paper, we address the problem of efficient routing in delay tolerant network. We propose a new routing protocol dubbed as ORION. In ORION, only a single copy of a data packet is kept in the network and transmitted, contact by contact, towards the destination. The aim of the ORION routing protocol is twofold: on one hand, it enhances the delivery ratio in networks where an end-to-end path does not necessarily exist, and on the other hand, it minimizes the routing delay and the network overhead to achieve better performance. In ORION, nodes are aware of their neighborhood by the mean of actual and statistical estimation of new contacts. ORION makes use of autoregressive moving average (ARMA) stochastic processes for best contact prediction and geographical coordinates for optimal greedy data packet forwarding. Simulation results have demonstrated that ORION outperforms other existing DTN routing protocols such as PRoPHET in terms of end-to-end delay, packet delivery ratio, hop count and first packet arrival.

In this paper, we address the problem of efficient routing in delay tolerant networks. We propose a new routing protocol dubbed as ORION. In ORION, only a single copy of a data packet is kept in the network and transmitted, contact by contact, towards the destination. The aim of the ORION routing protocol is twofold: on one hand, it enhances the delivery ratio in networks where an end-to-end path does not necessarily exist, and on the other hand, it minimizes the routing delay and the network overhead to achieve better performances. With ORION, nodes are aware of their neighborhood by the mean of actual and statistical estimation of new contacts. ORION makes use of autoregressive moving average (ARMA) stochastic processes for best contact prediction and geographical coordinates for optimal greedy data packet forwarding. Simulation results have demonstrated that ORION outperforms other existing DTN routing protocols such as PRoPHET in terms of end-to-end delay, packet delivery ratio, hop count, first packet arrival and queues occupancy.

Ad Hoc Routing with Distributed Ordered Sequences

Mobile wireless networks have been gaining popularity since the turn of the new millennium as they enable communication to take place without fixed communication infrastructure. This form of communication, which has been made possible by radio links proved its usefulness during emergency medical rescues such as an Ebola pandemic, battlefield communications or other emergency situations, where quick communication is of paramount importance. Nature-inspired algorithms such as AntHocNet, AntSense, among other ant inspired techniques, have been mimicked in solving the communication challenges in wireless networks, but they focus mostly on the ‘next-hop’ in determining routing of data packets from the source to the destination, which tends to suffer from congestion-related problems. Ant routing methods focus more on next-hop neighbours when choosing the shortest path which might have many data packets and are prone to congestion. Focusing on the next-hop neighbours poses a challenge of having other nodes that end up being congested. This problem of routes being heavily used, often decreases throughput rates, leading to the proposed Queuing Ant Colony System (QUACS) which is a bio-inspired, complementing the queuing optimisation approach in routing of data packets across the network. The results of simulations show that QUACS performs better in throughput, packet delivery ratio, end-to-end delay and communication overhead than other ant routing algorithms. This study is particularly beneficial in the ad hoc networks where the QUACS routing method can greatly assist in faster communication and evacuation in emergency for treatment of patients during emergency medical rescue operations.

This paper presents "OR2", an adaptive path tuning scheme for mobile ad hoc networks. In OR2, the active path adapts dynamically to node mobility without any link failures based on the local link quality. Most conventional routing protocols accommodate the change of network topology only when the link fails. Unless the movement of intermediate nodes leads to any link failures, they cannot adapt to the network topology even if other routes with less hop count become available. In contrast to these protocols, OR2 reduces the hop count of an active route while data packets are sent without link disconnection. Specifically, by introducing the notion of proximity that indicates the nearness of two communicating nodes, OR2 skips the upstream node in a proximity area and continues to shorten an active route as possible. For delay sensitive TCP flows, reducing the number of hops and path delay significantly improves the performance of TCP. We have implemented OR2 as an extension to DSR on FreeBSD. The experimental results have shown that OR2 is effective in enhancing TCP throughput and reducing end-to-end delay for all relevant flows.

We propose a novel routing protocol, RMR, for wireless tactical, high-mobility military networks that finds reliable routes through difficult terrains with possibly compromised regions. RMR uses an end-to-end reliability measure that includes both end-to-end connectivity as well as trustworthiness, and reactively discovers routes over spatial cells whose local reliability is proactively maintained by fast dissemination through the network. By using a space-centric approach where reliability is attributed to space rather than to nodes, RMR is able to find reliable routes through space that persist for longer durations than node-centric protocols. Via QualNet simulation studies, we compare the performance of our protocol with AODV in terms of end-to-end reliability as well as delay, and packet delivery ratio (PDR), and quantify the effects of node density, velocity, and traffic load on these performance metrics.

In recent times, different routing protocols have been proposed in the Internet of Things enabled Underwater Wireless Sensor Networks (IoT-UWSNs) to explore the underwater environment for different purposes, i.e., scientific and military purposes. However, high Energy Consumption (EC), End to End (E2E) delay, low Packet Delivery Ratio (PDR) and minimum network lifetime make the energy efficient communication a challenging task in Underwater Wireless Sensor Network (UWSN). The high E2E delay, EC and reliable data delivery are the critical issues, which play an important role to enhance the network throughput. So, this paper presents two energy efficient routing protocols namely: Shortest Path-Collision avoidance Based Energy Efficient Routing (SP-CBE2R) protocol and Improved-Collision avoidance Based Energy Efficient Routing (Im-CBE2R) protocol. At this end, both routing protocols minimize the probability of void hole occurrence and in return minimizes the EC and E2E delay. In both routing protocols, courier nodes are positioned at different strategic locations to keep the greedy forwarding continuous. The proposed routing protocols are also analyzed by varying the Packet Size (PS) and Data Rate (DR). Additionally, various simulations have been performed to authenticate the proposed routing protocols. Simulation results show that the proposed routing protocols outperform the baseline routing protocols in counterparts.