EM channel characteristics and their impact on MAC layer performance in underwater surveillance networks

Wireless communications and multihop networking based on electromagnetic (EM) radios have been considered as an alternative to acoustic communications in seawater because in typical applications for networked underwater sensing, EM waves are much less susceptible to multipath distortion and environmental noise. In this paper, we discuss the characteristics of EM channels in seawater and derive a novel EM signal propagation model. Based on the propagation model, we implement in the QualNet network simulator an EM underwater surveillance network for studying the impact of these unique characteristics of underwater EM channels on the media access control (MAC) layer performance. Both a single‐hop network model and a multihop network model are simulated. Simulation results show that the carrier sense multiple access without or with acknowledgement (CSMAWithoutACK or CSMAWithACK, respectively) has advantages over ALOHA and multiple access with collision avoidance in terms of packet average delay, packet delivery ratio, and MAC scheme overhead. In the multihop network model, the use of CSMAWithoutACK significantly reduces the packet average delay and the MAC scheme overhead, and both CSMAWithoutACK and CSMAWithACK achieve more than 90% packet delivery ratio. Therefore, CSMAWithoutACK (with no handshaking via request‐to‐send and clear‐to‐send control packets) is the most appropriate MAC protocol to be used in multihop EM‐based underwater surveillance networks. © Her Majesty the Queen in Right of Canada 2014. Reproduced with the permission of the Minister of Industry Canada     

Improved video streaming using MSVC and nonoverlapping zone routing multipath propagation over MANETs

Providing real‐time video streaming in mobile ad hoc networks is difficult because of the time‐dependent channel status and stringent service requirements. The currently existing route request‐reply–based multihop overlay networks cause considerable control overheads in video transmission resulting in loss of data and communication breakdown. Such networks are more suitable to nonstreaming video applications rather than to time‐sensitive video streaming applications. Therefore, a powerful mechanism needs to be adopted to handle the channel failures amicably and reduce latency effectively in time critical video streaming applications over mobile ad hoc networks. In order to be resilient to the channel failures and reduce latency in such applications, 2 strategies, namely, multistate video coding and 2‐tier–based nonoverlapping zone routing multipath propagation through directional antennas have respectively been incorporated. The performance of the proposed nonoverlapping zone routing multipath propagation system is compared with those of the existing multicast zone routing and zone‐based hierarchical link state routing protocols with parameters average end‐to‐end delay, routing overhead and packet delivery ratio using NS 2.34. The simulation results show that latency and resilience get considerably improved. Finally, the video quality of the proposed work has been verified by subjective and objective video testing methods.     

DFEMD: Delay Tolerant Fast Emergency Message Dissemination Routing Protocol

In vehicular ad-hoc network, vehicles are move very speedy thus their topology is changing frequently and intermittent connectivity occur often. The intermittent connectivity network (delay and disruption-tolerant network) resulting is end to end path is absent. In this intermittent network connectivity areas, during emergency event occurs, emergency rescue message (Example: Fire, Accident, etc.,) are sent to a rescue team is most necessary. Due to these constraints, general ad hoc protocol approaches is not suitable and, as a result, alternative protocol must be deliberated. This leads to the make a specific protocol mechanisms able to deliver both fast and trustworthiness in-order delivery emergency message needed. Thus we introduce the DFEMDR protocol, it follow the vehicular delay tolerant network (VDTN) common technique store carry-forward method and message replicas. This paper describes an efficient Delay tolerant Fast Emergency Message Dissemination Routing Protocol, called DFEMD routing protocol. This protocol enables in VDTN, the source node broadcast an emergency message to all available node in its communication range. The source node allocates a message replicas and message time to live to the neighbour nodes (forwarded node) based on that node has credence value. Credence value is calculated to all nodes based on two values; the first value is visited level estimation, it is calculated based on the number of nodes previously visited by the node. The second value is Destination Reaches Level Estimation (DLE); it is calculated based on the number of times the node successfully delivered the message to the destination. Finally, each node credence value is calculated, from this visited level and destination reaches level estimation values. Finally, the trust authority received emergency messages and evaluate the trustworthiness of message based on message reputation value or message confidence value.

     

Novel Section‐Based Joint Network Coding and Scheduling Scheme in WMNs: JNCS

Guaranteeing quality of service over a multihop wireless network is difficult because end‐to‐end (ETE) delay is accumulated at each hop in a multihop flow. Recently, research has been conducted on network coding (NC) schemes as an alternative mechanism to significantly increase the utilization of valuable resources in multihop wireless networks. This paper proposes a new section‐based joint NC and scheduling scheme that can reduce ETE delay and enhance resource efficiency in a multihop wireless network. Next, this paper derives the average ETE delay of the proposed scheme and simulates a TDMA network where the proposed scheme is deployed. Finally, this paper compares the performance of the proposed scheme with that of the conventional sequential scheduling scheme. From the performance analysis and simulation results, the proposed scheme gives more delay‐ and energy‐efficient slot assignments even if the NC operation is applied, resulting in a use of fewer network resources and a reduction in ETE delay.     

A Multichannel TDMA MAC Protocol to Reduce End‐to‐End Delay in Wireless Mesh Networks

Supporting QoS over multihop wireless mesh networks is difficult because end‐to‐end delay increases quickly with the increasing number of hops. This paper introduces a novel multichannel time‐division multiple‐access media access control (McTMAC) protocol that can help to efficiently reduce delay over multihop networks. Performance evaluation results demonstrate that McTMAC outperforms existing alternative protocols. The max‐delay can be reduced by as much as 60% by using McTMAC.     

A simple void node and loop‐free three‐dimensional routing protocol for multi‐hop wireless networks

Wireless networks are now very essential part for modern ubiquitous communication systems. The design of efficient routing and scheduling techniques for such networks have gained importance to ensure reliable communication. Most of the currently proposed geographic routing protocols are designed for 2D spatial distribution of user nodes, although in many practical scenarios user nodes may be deployed in 3D space also. In this paper, we propose 3D routing protocols for multihop wireless networks that may be implemented in two different ways depending on how the routing paths are computed. When the routing paths to different user nodes from the base station in the wireless network are computed by the base station, we call it centralized protocol (3DMA‐CS). A distributed routing (3DMA‐DS) protocol is implemented when respective routing path of each user node to the base station is computed by the user node. In both of these protocols, the user (base station) selects the relay node to forward packets in the direction of destination, from the set of its neighbours, which makes minimum angle with the reference line drawn from user (base station) to the base station (user), within its transmission range. The proposed protocols are free from looping problem and can solve the void node problem (VNP) of multihop wireless networks. Performance analysis of the proposed protocol is shown by calculating end‐to‐end throughput, average path length, end‐to‐end delay, and energy consumption of each routing path through extensive simulation under different network densities and transmission ranges.     

Efficient multihop transmission scheme for error‐free relay forwarding in cooperative networks

Multihop cooperative communication is emerging as a key concept to extend the coverage area of the network and potentially increase the capacity. The spectral efficiency of such networks can be improved by adapting the transmission to time‐varying channel conditions, referred to as incremental relaying. Although such incremental relaying concepts are progressively being studied, many challenges, such as erroneous transmissions by intermediate nodes and end‐to‐end delay of the network, limit its practical use due to lack of an efficient implementation. This paper proposes an efficient multihop incremental relaying technique. In this method, erroneous relay forwarding is mitigated, and the overhead for coordination among nodes is reduced by exploiting the implicit feedback channel available due to the broadcast nature of wireless transmissions. The proposed scheme fully leverages the benefit of overhearing and eliminates the additional feedback slots required for validation. Further, it ensures reliable forwarding of information, which optimizes the throughput of multihop networks. Thorough analysis of the proposed scheme is performed under different deployment environments, and the theoretical analyses presented in this paper are supported with results from extensive simulation studies. Copyright © 2013 John Wiley & Sons, Ltd.     

Resequencing of Messages in Communication Networks

In this paper we study a message resequencing problem in a store-and-forward computer network where messages may go out of order while traversing logical channels. The logical channels are assumed to consist of multiple physical links which may be of different capacities. A message is dispatched to the fastest available link. Resequencing methods suggested in the literature [3] (resequencing at the channel level and resequencing at the virtual circuit level) are investigated for this link selection rule. The analysis is done on a two-node network connected by multiple links. The source node together with the set of outgoing links are modeled as anM/M/mqueue with servers of different rates. The resequencing delay distribution and the average resequencing delay are derived. On multihop networks, the effect of message length, link numbers, link service rates, and the resequencing methods on resequeucing delay are investigated by simulation.     

Gravitational outlier detection for wireless sensor networks

Accuracy of sensed data and reliable delivery are the key concerns in addition to several other network‐related issues in wireless sensor networks (WSNs). Early detection of outliers reduces subsequent unwanted transmissions, thus preserving network resources. Recent techniques on outlier detection in WSNs are computationally expensive and based on message exchange. Message exchange‐based techniques incur communication overhead and are less preferred in WSNs. On the other hand, machine learning‐based outlier detection techniques are computationally expensive for resource constraint sensor nodes. The novelty of this paper is that it proposes a simple, non message exchange based, in‐network, real‐time outlier detection algorithm based on Newton's law of gravity. The mechanism is evaluated for its accuracy in detecting outliers, computational cost, and its influence on the network traffic and delay. The outlier detection mechanism resulted in almost 100% detection accuracy. Because the mechanism involves no message exchanges, there is a significant reduction in network traffic, energy consumption and end‐to‐end delay. An extension of the proposed algorithm for transient data sets is proposed, and analytic evaluation justifies that the mechanism is reactive to time series data. Copyright © 2016 John Wiley & Sons, Ltd.     

Multiframe message broadcast in agility link based navigation satellite network

The agility link based navigation satellite network suffers from a lack of continuous end‐to‐end connectivity. Message transmitting relies on a store‐forward mechanism—ie, data are sent from one node to another, depending on the communication opportunities, termed contacts, which arise when 2 nodes are connected by a link. To address the technical issues in such networks, the common approach is termed delay‐tolerant networking. However, the problem becomes more complicated when the message is subdivided into several frames for the limited transmission capacity of one contact. In this paper, we formalize the multiframe message broadcast problem where node may possess different knowledge, such as contact plans and message distribution, which depict the state of network and is helpful for data transmission. With the different amount of the knowledge, we investigate several different transmission strategies. And we propose the theoretical models to evaluate the above transmission strategies. Simulations prove the accuracy of our model. We also find that, as expected, the strategy using more knowledge tends to perform better. To the best of our knowledge this is the first investigation of multiframe message broadcast issues in the agility link based navigation satellite network.     

Cross-Layer Collaborative In-Network Processing in Multihop Wireless Sensor Networks

Emerging wireless sensor network (WSN) applications demand considerable computation capacity for in-network processing. To achieve the required processing capacity, cross-layer collaborative in-network processing among sensors emerges as a promising solution: sensors do not only process information at the application layer, but also synchronize their communication activities to exchange partially processed data for parallel processing. However, scheduling computation and communication events is a challenging problem in WSNs due to limited resource availability and shared communication medium. In this work, an application-independent task mapping and scheduling solution in multihop homogeneous WSNs, multihop task mapping and scheduling (MTMS), is presented that provides real-time guarantees. Using our proposed application model, the multihop channel model, and the communication scheduling algorithm, computation tasks and associated communication events are scheduled simultaneously. The dynamic voltage scaling (DVS) algorithm is presented to further optimize energy consumption. Simulation results show significant performance improvements compared with existing mechanisms in terms of minimizing energy consumption subject to delay constraints     

Distributed space-time coding for multihop transmission in power line communication networks

In this paper, we consider transmission in relatively wide-stretched power line communication (PLC) networks, where repeaters are required to bridge the source-to-destination distance. In particular, it is assumed that each network node is a potential repeater and that multihop transmission is accomplished in an ad hoc fashion without the need for complex routing protocols. In such a scenario, due to the broadcasting nature of the power line channel, multiple repeater nodes may receive and retransmit the source message simultaneously. It is shown that, if no further signal processing is applied at the transmitter, simultaneous retransmission often deteriorates performance compared with single-node retransmission. We therefore advocate the application of distributed space-time block codes (DSTBCs) to the problem at hand. More specifically, we propose that each network node is assigned a unique signature sequence, which allows efficient combining at the receiver. Most notably, DSTBC-based retransmission does not require explicit collaboration among network nodes for multihop transmission and detection complexity is not increased compared with single-node retransmission. Numerical results for multihop transmission over PLC networks show that DSTBC-based retransmission achieves a considerably improved performance in terms of required transmit power and multihop delay compared with alternative retransmission strategies.     

A mobicast routing protocol with carry‐and‐forward in vehicular ad hoc networks

In vehicular networks, safety and comfort applications are two quite different kinds of applications to avoid the emergency traffic accident and enjoy the non‐emergency entertainment. The comfort application drives the challenges of new non‐emergency entertainments for vehicular ad hoc networks (VANETs). The comfort application usually keeps the delay‐tolerant capability; that is, messages initiated from a specific vehicle at time t can be delivered through VANETs to some vehicles within a given constrained delay time λ. In this paper, we investigate a new mobicast protocol to support comfort applications for a highway scenario in VANETs. All vehicles are located in a geographic zone (denoted as zone of relevance (ZOR)) at time t; the mobicast routing must disseminate the data message initiated from a specific vehicle to all vehicles that have ever appeared in ZOR at time t. This data dissemination must be performed before time t + λ through the carry‐and‐forward technique. In addition, the temporary network fragmentation problem is considered in our protocol design. Also, the low degree of channel utilization is kept to reserve the resource for safety applications. To illustrate the performance achievement, simulation results are examined in terms of message overhead, dissemination success rate, and accumulative packet delivery delay. Copyright © 2012 John Wiley & Sons, Ltd.     

HARQ–ARQ interaction method for LTE‐based mobile satellite communication system

Hybrid automatic repeat request (HARQ) and automatic repeat request (ARQ) of the terrestrial long‐term evolution (LTE) system are designed considering the very short propagation delay of terrestrial environment. Therefore, when HARQ and ARQ are applied to the LTE‐based mobile satellite communication system, the inefficiency is caused by the long propagation delay of satellite environment. This paper proposes the interaction method between HARQ and ARQ for the decrease of inefficiency in the LTE‐based mobile satellite communication system. The existing concept of layered architecture about HARQ and ARQ is also maintained in our interaction method. Simulation results reveal that our proposed scheme can provide the larger spectrum efficiency than that of the non‐interaction scheme in all environments. The performance improvement can be up to 2.04 times through the interaction method. Copyright © 2014 John Wiley & Sons, Ltd.     

Slot allocation strategies for delay sensitive traffic support in asynchronous ad hoc wireless networks

Supporting real‐time traffic in ad hoc wireless networks is considered as a challenging problem. Existing bandwidth reservation mechanisms assume a TDMA environment where achieving time synchronisation is expensive in terms of resources. Heuristics that exist for slot allocation schemes assume a CDMA over TDMA model in order to alleviate the presence of hidden terminals. Slot allocation strategies in the presence of hidden terminals assume significance in a single channel system for supporting delay sensitive traffic. In this paper, we propose three heuristics for the slot allocation process in asynchronou single channel multihop wireless networks in the presence of hidden terminals. The heuristics we propose are the early fit reservation (EFR), minimum bandwidth‐based reservation (MBR) and position‐based hybrid reservation (PHR). The EFR heuristic assigns bandwidth link‐by‐link in the forward path. The MBR heuristic allocates bandwidth to the links in the increasing order of free conn‐slots. The PHR heuristic assigns bandwidth for every link proportional to its position in the path. Simulation studies show that EFR performs better in terms of delay characteristics. MBR provides better call blocking performance at the cost of high end‐to‐end delay. PHR provides a better delay performance compared to MBR and better call blocking performance comparedto EFR. Copyright © 2004 John Wiley & Sons, Ltd.     

Graph‐based optimal asynchronous scheduling in large propagation delay underwater acoustic sensor networks

Optimal scheduling is essential to minimize the time wastage and maximize throughput in high propagation delay networks such as in underwater and satellite communication. Understanding the drawbacks of synchronous scheduling, this paper addresses an asynchronous optimal scheduling problem to minimize the time wastage during the transmission. The proposed scheduling problem is analyzed in both broadcast and non‐broadcast networks, which is highly applicable in high propagation delay networks. In broadcast networks, the proposed scheduling method reduces to a graph‐theoretic model that is shown to be equivalent to the classic algorithmic asymmetric traveling salesman problem (TSP) which is NP‐Hard. Although it is NP‐Hard, the TSP is well‐investigated with many available methods to find the best solution for up to tens of thousands of nodes. In non‐broadcast networks, the optimal solution to the scheduling problem considers the possibility of parallel transmission, which is optimized using graph coloring algorithm. The groups obtained through graph coloring are solved using Asymmetric Traveling Salesman algorithm to obtain the optimal schedule. The proposed method efficiently solves the scheduling problem for networks of practical size.     

Investigation of maximum lifetime and minimum delay trade‐off in underwater sensor networks

Underwater acoustic sensor networks (UASNs) are subjected to harsh characteristics of underwater acoustic channel such as severe path losses, noise, and high propagation delays. Among these constraints, propagation delay (more generally, end‐to‐end delay) is the most dominating limitation especially for time‐critical UASN applications. Although the minimization of end‐to‐end delay can be achieved by using the minimum hop routing, this solution cannot lead prolonged lifetimes since nodes consume excessive energy for transmission over long links. On the other hand, the maximization of network lifetime is possible by using energy efficient paths, which consist of relatively short links but high number of hops. However, this solution results in long end‐to‐end delays. Hence, there is a trade‐off between maximizing the network lifetime and minimizing the end‐to‐end delay in UASNs. In this work, we develop a novel multi‐objective–optimization (MOO) model that jointly maximizes the network lifetime while minimizing the end‐to‐end delay. We systematically analyze the effects of limiting the end‐to‐end delay on UASN lifetime. Our results reveal that the minimum end‐to‐end delay routing solution results in at most 72.93% reduction in maximum network lifetimes obtained without any restrictions on the end‐to‐end delay. Nevertheless, relaxing the minimum end‐to‐end delay constraint at least by 30.91% yields negligible reductions in maximum network lifetimes.     

A secure end‐to‐end SMS‐based mobile banking protocol

Short message service (SMS) provides a wide channel of communication for banking in mobile commerce and mobile payment. The transmission of SMS is not secure in the network using global system for mobile communications or general packet radio service. Security threats in SMS restricted the use of SMS in mobile banking within certain limits. This paper proposed a model to address the security of SMS using elliptic curve cryptography. The proposed model provides end‐to‐end SMS communication between the customer and the bank through the mobile application. The main objective of the proposed model is to design and develop a security framework for SMS banking. Further, the protocol is verified for its correctness and security properties because most of the protocols are not having the facility to be verified by using the formal methods. Our proposed framework is experimentally validated by formal methods using model checking tool called automated validation of internet security protocols and Scyther tools. Security analysis shows that the proposed mechanism works better compared to existing SMS payment protocols for real‐world applications.     

Information Propagation through Opportunistic Communication in Mobile Social Networks

At present, people can communicate with each other through short range communication technologies (Bluetooth, WiFi, etc.) installed in their smart terminals. Due to limited communication range, communication is opportunistic, and mobile social networks formed by such technologies can be seen as delay tolerant networks (DTN). This paper presents a theoretical framework to evaluate the performance of information propagation in such network based on ODE equations. This framework can evaluate the impact of peoples?? many behaviors. For example, people may not want to help others because of their selfish nature. In addition, peoples who are not interested in the message may not receive the message at all, but they become to be interested in the message later. On the other hand, people may discard the message after they used it. We check the accuracy of our model through simulations based on both synthetic and real motion traces (the average deviation is not bigger than 5.09?%). Numerical results show that peoples?? behaviors really have certain impact on the performance of information propagation. For example, if the selfish level is bigger, some persons cannot obtain message at all. If peoples discard message with bigger probability, above result may also appear.     

Secure data communication in mobile ad hoc networks

We address the problem of secure and fault-tolerant communication in the presence of adversaries across a multihop wireless network with frequently changing topology. To effectively cope with arbitrary malicious disruption of data transmissions, we propose and evaluate the secure message transmission (SMT) protocol and its alternative, the secure single-path (SSP) protocol. Among the salient features of SMT and SSP is their ability to operate solely in an end-to-end manner and without restrictive assumptions on the network trust and security associations. As a result, the protocols are applicable to a wide range of network architectures. We demonstrate that highly reliable communication can be sustained with small delay and small delay variability, even when a substantial portion of the network nodes systematically or intermittently disrupt communication. SMT and SSP robustly detect transmission failures and continuously configure their operation to avoid and tolerate data loss, and to ensure the availability of communication. This is achieved at the expense of moderate transmission and routing overhead, which can be traded off for delay. Overall, the ability of the protocols to mitigate both malicious and benign faults allows fast and reliable data transport even in highly adverse network environments.