Redundant Messages Research Articles

A Scalable Indirect Position-Based Causal Diffusion Protocol for Vehicular Networks

Emerging applications based on vehicular ad-hoc networks (VANETs) are focused on offering new services to intelligent transportation systems (ITSs), such as traffic safety and management. For such kind of services, there are intrinsic spatial and temporal dependencies in the communication among mobile and fixed components. However, the characteristics of VANETs, which include a rapidly changing topology and the lack of global temporal references, make it difficult to satisfy such communication constraints. Commonly, the communication protocols for VANETs assume high coupled communication links; nevertheless, for most ITSs, the entities to whom such information will be useful are determined at run time by the spatial and temporal context. In this paper, a causal position-based indirect communication protocol is proposed, which allows road side units (RSUs) to disseminate messages with an uncoupled communication. The proposed solution uses the vehicles as opportunistic carriers, leveraging the bounded movement in a specific geographical region to exchange data among RSUs even with unknown recipients. To preserve the coherence of the exchange of messages, they are ordered by establishing their causal dependencies without the requirement of global references or synchronized physical clocks. Furthermore, the proposed protocol leverages message redundancy to recover some lost messages during the transmission. It is analytically demonstrated that the protocol is scalable since the size of the control information depends only on the number of RSUs rather than on the total number of entities in the system.

A mobility-aware approach for distributed data update on unstructured mobile P2P networks

In unstructured mobile peer-to-peer systems (MP2P), the frequent link breakages lead frequent topology mismatching problems and data transmission failures due to high mobility of nodes. The overhead of data transmission and synchronization cannot be neglected. In order to keep the data consistent, flooding is a fundamental and straightforward data synchronization mechanism since a mobile node does not know which else has the same shared data item. However, data flooding causes the broadcast storm problem. In this paper, we propose a mobility-aware data update approach (MADU) to improve the data dissemination and to reduce the overhead of maintaining the consistency of shared data items in an MP2P network. We use safe-time which is derived from the neighbor’s location and speed to determine the time for a node to do the checking and updating between the neighbor nodes and itself. We also consider the network connectivity of a mobile node and access frequency of a data item as the factors to trigger the update process. By combining the mobility information of nodes, network connectivity, and access frequency of data items, we set a reasonable data update mechanism, which can significantly decrease the number of retransmissions and redundant messages so as to reduce the overhead of maintaining the data consistency.

The interdependence of frequency, predictability, and informativity in the segmental domain

Abstract It has long been noted that language production seems to reflect a correlation between message redundancy and signal reduction. More frequent words and contextually predictable instances of words, for example, tend to be produced with shorter and less clear signals. The same tendency is observed in the language code (e.g. the phonological lexicon), where more frequent words and words that are typically contextually predictable tend to have fewer segments or syllables. Average predictability in context (informativity) also seems to be an important factor in understanding phonological alternations. What has received little attention so far is the relation between various information-theoretic indices – such as frequency, contextual predictability, and informativity. Although each of these indices has been associated with different theories about the source of the redundancy-reduction link, different indices tend to be highly correlated in natural language, making it difficult to tease apart their effects. We present a computational approach to this problem. We assess the correlations between frequency, predictability, and informativity, and assess when these correlations are likely to create spurious (null or non-null) effects depending on, for example, the amount of data available to the researcher.

On Efficient Scheduling of H2H Traffic and Reducing Signaling Overhead due to Uplink Small Data M2M Traffic in LTE-A Networks

Large coverage and global connectivity makes cellular networks as preferred choice for internet of things (IoT). Machine-to-machine (M2M) communications deal with communication and networking aspects of IoT. Since, cellular networks are optimized to support human-to-human (H2H) communication (e.g., Voice calls, Internet), incorporating M2M communication may affect the QoS of the former. Also, the large number of M2M devices incur significant signaling overhead on both core network (CN) and radio access network (RAN). In LTE-A networks, EPS bearer establishment procedure to connect a device to the PDN gateway involves several signaling messages exchange between the device and the network. M2M devices mostly generate traffic of low volume and less frequent, in nature. So, it is very uneconomical to have rigorous signaling messages exchange to send few bytes of data. In this paper, we first studied class based dynamic priority (CBDP) algorithm Giluka et al. (in: Proceedings of IEEE WF-IoT, 2014), which is a delay aware radio resource scheduling algorithm to support uplink M2M traffic with minimal effect on QoS of uplink H2H traffic. Further, we modeled the optimal behavior of the CBDP algorithm and compared with its behavior in practical scenarios. Apart from this, we propose a lightweight EPS bearer establishment procedure to be followed by M2M devices sending small data, in which M2M small data is piggybacked with control message. Further, in the same procedure, redundant signaling messages for small data transmission (SDT) are carefully removed preserving the security aspects of the system. To ensure security for the small data transmitted, a new insightful technique of replacing authentication with confidentiality is conceived. With this, we propose an enhanced version of CBDP algorithm, named as Non-SDT-CBDP algorithm or NSDT-CBDP algorithm, which schedules resources only to H2H and NSDT-M2M flows while SDT-M2M flows are piggybacked with Message 3 (MSG-3) of lightweight EPS bearer establishment procedure. The simulation results show performance gain of NSDT-CBDP over CBDP, specially for class-3 M2M and class-4 H2H. The NSDT-CBDP algorithm show percentage reduction in packet loss ratio by 25% for class-3 M2M, percentage reduction in end-to-end delay by 11 and 19% for class-4 H2H and class-3 M2M, percentage gain in throughput by 27 and 19% for class-4 H2H and class-3 M2M. Apart from this, NSDT-CBDP algorithm is able to allocate 12% more RBs to H2H devices in comparison to CBDP algorithm.

A Bursty Multi-node Handover scheme for mobile internet using the partially Distributed Mobility Management (BMH–DMM) architecture

In the wireless network and mobile internet, several mobile nodes (MNs) may handover from the same previous network X to the same destination network Y at the same time. However, currently proposed Distributed Mobility Management (DMM)-based protocol mainly focus on the handover processing of a single MN’s handover. It causes many redundant messages’ exchanging when multiple MNs do handover at the same time. In this paper, a Bursty Multi-node Handover scheme for mobile internet using the partially Distributed Mobility Management (BMH–DMM) architecture is proposed to tackle the aforementioned problem. Using the proposed BMH–DMM method, one set of control messages for handover is used instead of n sets of control messages for a group that has n MNs. The performance analysis shown that when the number of MNs that perform handover at the same time and in the same place is increased, the handover overhead is not increased so much, for which the proposed BMH–DMM method can reduce about 30% bandwidth consumption for exchanging handover’s signaling messages. Furthermore, the network utilization, handover delay, packet loss, handover blocking probability of using the proposed BMH–DMM scheme are also smaller than that of using the individual handover approach.

Flooding in 3-dimensional mobile ad hoc networks using 1-hop information

Flooding is a fundamental problem in mobile ad hoc networks (MANETs). In traditional pure flooding, a node retransmits a flooding message to all its neighbours when it firstly receives the message. The pure flooding suffers from excessive redundancy of transmissions, which causes high overhead and severe interference of the network. Therefore, many flooding algorithms have been proposed to reduce the redundancy of messages. However, former works mostly focus on 2-dimensional MANETs, and their approaches are hard to be extended to 3-dimensional wireless networks. In this paper, we consider the flooding problem for 3-dimensional MANETs. We propose an efficient flooding algorithm using only 1-hop neighbours information to optimise running time of the algorithm. Under the premise of ensuring full delivery, the proposed algorithm selects a minimum set of neighbours for each node to forward messages for reducing redundant transmissions. Simulations have been conducted and the results have shown that the proposed algorithm significantly decreases required transmissions for a flooding.

SMARTER THAN YOUR AVERAGE SENSOR: AIS SENSOR THAT INTELLIGENTLY RE-TRANSMITS MEANINGFUL INFORMATION DERIVED FROM RAWAIS DATA IN NETWORK LIMITED AREAS

Abstract. AIS is a transponder based, anti-collision system used by the majority of ocean traffic. Ships regularly transmit their identity, position and speed. The information used to populate the AIS fields come from ship based sensors, such as GPS, and user populated fields, such as the vessels name and MMSI number. These fields are susceptible to spoofing and can be changed to hide the identity or location of a vessel. This is often done to disguise the vessel as a different class to avoid inspections or to enter a protected area without raising alarms. The AIS system has found great utility in monitoring global shipping trends and traffic but this was never intended when the protocol was designed. Docked vessels still transmit messages regularly that contain no new information. These, and other redundant messages, are still transmitted and stored. In situations where a sensor is remote and has limited access to the Internet this can become costly. The Smart-AIS sensor records all incoming messages locally and makes a decision on whether the message is of special interest or not. Messages of interest are re-transmitted to an external AIS database.

A Combinational Buffer Management Scheme in Mobile Opportunistic Network

Nodes in Mobile Opportunistic Network (MON) have to cache packets to deal with the intermittent connection. The buffer management strategy obviously impacts the performance of MON, and it attracts more attention recently. Due to the limited storage capacity of nodes, traditional buffer management strategies just drop messages based on the property of message, and they neglect the collaboration between neighbors, resulting in an ineffective performance improvement. Therefore, effective buffer management strategies are necessary to ensure that each node has enough buffer space to store the message when the node buffer is close to congestion. In this paper, we propose a buffer management strategy by integrating the characteristics of messages and nodes, and migrate the redundant messages to the neighbor to optimize the total utility, instead of deleting them. The simulation experiment results show that it can obviously improve the delivery ratio, the overhead ratio and the average delays, and reduce the amount of hops compared with the traditional ones.

Immunization-based redundancy elimination in Mobile Opportunistic Networks-Generated big data

Diverse sensors and smart devices are promising in facilitating to perform specific tasks which generate massive data whilst such data transmission is challenged in the big data era. Under some circumstances, these devices may form Mobile Opportunistic Networks (MONs) which are characterized by intermittent connectivity. In such scenarios, there is a critical issue that nodes with the already delivered message copies may continue carrying and transmitting the copies if they are not informed that the message has been delivered. This may result in redundant data, and thus large consumption of network resources and network performance degradation. To avoid generating, transmitting and storing unwanted data due to redundant message copies, we propose an Immunization-Based Redundancy Elimination scheme (IBRE) in MONs to stop useless data transmission and flush redundancy. In IBRE, each destination independently selects the right number of ACKs distributed to respond to the variation of the amount of redundant data in a dynamic fashion. Simulation results demonstrate that IBRE suppresses redundant data transmission and eliminates useless data generated from redundant message copies in cost-efficient manner.

DoS Attacks in Internet of Things

The Internet of Things (IoT) defines a highly interconnected network of heterogeneous devices where all kinds of communications seem to be possible, even unauthorized ones. As a result, the security requirement for such network becomes critical whilst common standard Internet security protocols are recognized as unusable in this type of networks, particularly due to some classes of IoT devices with constrained resources. Due to the limitations of energy, computation and storage for sensors, although IoT have been widely deployed in many applications such as military, ecological and health-related areas. It is a critical challenge to present the effective and lightweight security protocol to prevent various attacks for IoT, especially for the denial of service (DoS) attack. Normally, the adversaries compromise sensors and launch the DoS attack by replaying redundant messages or making overdose of fake messages. In this paper, we explore the scope of the DoS attack problem in IoT. First we outline the constraints, security requirements, and then explore types of DoS attacks in IoT.

A group-based data-driven approach for data synchronization in unstructured mobile P2P systems

This paper addresses the problem of data consistency on mobile peer-to-peer (MP2P) systems (or MP2P networks). The considered MP2P system is based on a mobile ad-hoc network, where the energy and connectivity on the mobile devices are limited. Since different mobile nodes may store copies of shared information, data synchronization on an MP2P system becomes crucial and challenging due to frequent disconnection and change on network topology caused by node mobility. We propose an effective approach to improving the performance of data synchronization with a dynamic inverted data indexing structure and group-based data-driven consistency management. The proposed approach can effectively synchronize the data items without using a central cache node in each group (or cluster) and perform well in terms of the coverage of successfully synchronized nodes and the number of redundant messages. Last, the proposed approach is validated through extensive simulation experiments.

Flooding in 3-Dimensional Mobile Ad Hoc Networks Using 1-Hop Information

Flooding is a fundamental problem in mobile ad hoc networks (MANETs). In traditional pure flooding, a node retransmits a flooding message to all its neighbours when it firstly receives the message. The pure flooding suffers from excessive redundancy of transmissions, which causes high overhead and severe interference of the network. Therefore, many flooding algorithms have been proposed to reduce the redundancy of messages. However, former works mostly focus on 2-dimensional MANETs, and their approaches are hard to be extended to 3-dimensional wireless networks. In this paper, we consider the flooding problem for 3-dimensional MANETs. We propose an efficient flooding algorithm using only 1-hop neighbours information to optimise running time of the algorithm. Under the premise of ensuring full delivery, the proposed algorithm selects a minimum set of neighbours for each node to forward messages for reducing redundant transmissions. Simulations have been conducted and the results have shown that the proposed algorithm significantly decreases required transmissions for a flooding.

Regular-hexagon-equilateral-triangle area grouping–based broadcast protocol for safety message in urban vehicular ad hoc networks

Road-based directional broadcast protocols are proposed in the literatures to offset efficiency of message dissemination of traditional broadcast protocol in urban vehicular ad hoc networks. However, these protocols cannot provide enough reliability and efficiency for vehicles’ misclassification at intersection or on straight road. Therefore, we present regular-hexagon-equilateral-triangle area grouping–based broadcast protocol for urban vehicular ad hoc networks. The area covered by relay node is averagely divided using regular-hexagon-equilateral-triangle, and vehicles are grouped according to the area that they reside. The algorithm for constructing regular-hexagon-equilateral-triangle is proposed. We adopt same vehicles’ grouping method at intersection and on straight road, and no neighbor list is maintained to identify road intersection. We design waiting time formula to calculate time for node forwarding message. It is ruled that node with waiting time dropping to zero first is defined as the relay node, and this relay node transmits message. So there is only one relay node which forwards message in each group. It also rules in regular-hexagon-equilateral-triangle area grouping–based broadcast protocol that each relay node forwards the same message only once, therefore, it limits redundant message retransmission. Using the vehicles’ grouping method and selection strategy of relay node as mentioned above, the proposed protocol enables message to be transmitted in different directions along different roads at the same time. Simulation indicates that our protocol has a better performance

Simulation, modeling and analysis of master node election algorithm based on signal strength for VANETs through Colored Petri nets

The broadcast storm problem causes redundancy, contention and collision of messages in a network, particularly in vehicular ad hoc networks (VANETs) where number of participants can grow arbitrarily. This paper presents a solution to this problem in which a node is designated as a master through an election process. Moreover, an algorithm is proposed for asynchronous VANETs to select a master node, where the participants (i.e., vehicles) can communicate with each other directly (single-hop). The proposed algorithm is extrema-finding in a way that a node having maximum signal strength is elected as a master node and each vehicle continues communication with the master until the master node keeps its signal strength at the highest level and remains operational too. This paper further presents the Petri net-based modeling of the proposed algorithm for evaluation which is going to be presented for the first time in leader election algorithm in VANETs. Verification of the proposed algorithm is carried out through state space analysis technique.

A heuristic data update mechanism in unstructured mobile P2P systems

With the advances in information and communication technology, the unstructured mobile peer-to-peer (MP2P) system based on a hybrid mobile ad-hoc network (hybrid MANETs), where the membership between mobile nodes is more dynamic and the energy on each node is limited, becomes a trend. Since different mobile nodes may store copies of shared information, data synchronization on an MP2P system is crucial for providing the latest information. Nevertheless, the node mobility makes the communication links disconnected and the network topology changed frequently. The maintenance on data consistency in an MP2P system thus becomes challenging. In this paper, we propose a heuristic data update mechanism (HDUM) to effectively maintain the data consistency in an MP2P system with less overhead. In HDUM, each node derives safe-time values from the neighbors’ locations and speeds to determine an appropriate time to check and update data items between the neighboring nodes and itself. HDUM also considers the relative node ability, which is derived from nodes connectivity, access frequency of a data item, and the residual capacity of battery. Relative node ability indicates the ability of a node with respect to a data item. If the ability value of a node is not lower than a given threshold, this node can be notified to receive updated data items from its neighbors. To evaluate the proposed HDUM, extensive simulated experiments are performed. The experimental results show that HDUM can keep higher coverage of successfully synchronized nodes while significantly reducing a large amount of redundant messages.

Limited area broadcast for warning message delivery over vehicular ad-hoc networks

Vehicular ad hoc networks have been developed in consideration of advancing driving safety. In driving-safety applications, rapid dissemination of warning messages is highly demanded to avoid accidents involving incoming vehicles. Broadcast transmission is considered the most appropriate technique to spread warning messages because it can simultaneously reach all neighboring nodes within a transmission range using only a brief wireless media access. However, blindly broadcasting redundant messages may severely overcrowd wireless media channels and provoke transmission collisions; this is known as the broadcast storm problem. In order to reduce broadcast redundancy, broadcasting must be intelligently controlled. Simultaneously, an intelligent broadcast scheme should aim to reduce the number of hops needed to arrive at a destination, to achieve smaller propagation delay. In this paper, we observed the behavior of a few broadcast schemes and found that their performances can be explained as limiting a space to control the number of contentions in broadcasting. From the observation, we propose a limited area-based (LAB) scheme to achieve a shorter propagation time as well as a smaller number of redundant broadcast messages. The proposed scheme can maintain a proper collision rate to obtain a faster propagation time by adjusting the size of an area in which broadcasting nodes belong. Performance evaluation results from simulation show that the proposed scheme is feasible and reasonable.

Directed broadcasting with mobility prediction for vehicular sensor networks

This article suggests a new directed broadcasting method with mobility prediction of moving vehicles in vehicular sensor networks (VSNs). VSNs can play a critical role to ensure prompt delivery of real-time sensing data and be able to prevent various road dangers. The suggested method is particularly for vehicle safety communication (VSC) on highway roads by using directed broadcasting between vehicles. In VSNs, broadcasting is the most suitable communication mechanism for VSC. The simplest broadcasting mechanism is flooding, which introduces the redundant message retransmission and the broadcast storm problem. It is because all vehicles rebroadcast the messages in flooding. The broadcast storm problem can be addressed with selective flooding schemes which select rebroadcast vehicles to perform rebroadcasting. However, selective flooding schemes cannot promise enough reliability for VSC because of the highly dynamic topology and frequent disconnections of vehicular networks. Fast movement and frequent topology changes cause repeated link breakages and it increases the packet loss rate of vehicular networks. In this article, we propose a mobility prediction-based directed broadcasting (MPDB) protocol to achieve a reliable broadcasting in VSNs. MPDB protocol broadcasts emergent messages only to the rear vehicles on the same road. MPDB protocol consists of two phases: (i) mobility prediction phase and (ii) broadcasting phase. The mobility prediction can be acquired through periodical beaconing. In mobility prediction phase, each vehicle gets its rear vehicle set on the same road through neighbour’s position, inter-vehicle distance, relative speed and moving direction. In broadcast phase, MPDB protocol selects a vehicle having the largest link available time (LAT) values acquired by the mobility prediction as a rebroadcast vehicle among the rear vehicle set acquired in previous phase. By using LAT for broadcasting propagation, MPDB protocol can intensify the reliability of the message dissemination and also prevent the broadcast storm problem in vehicular networks. The simulation results show that MPDB protocol has better performance improvement in terms of average packet rate and packet delay.

Signalling with a cryptic trait: the regularity of barred plumage in common waxbills.

Sexual signals often compromise camouflage because of their conspicuousness. Pigmentation patterns, on the contrary, aid in camouflage. It was hypothesized that a particular type of pattern—barred plumage in birds, whereby pigmented bars extend across feathers—could simultaneously signal individual quality, because disruptions of these patterns should be perceptually salient at close range and help assess plumage condition. Here we show that common waxbills (Estrilda astrild), which have extensive barred plumage, have more regular patterns as adults than as juveniles, and that adult males have more regular patterns than females. Both these differences are indicative of sexual signalling in species with conventional sex roles. More regular barred plumage was related to better body condition in adult males. Colour ornamentation traits were also related to aspects of quality, either the same as barred plumage (body condition) or a different one (good feather development), supporting both the ‘redundant message’ and the ‘multiple message’ hypotheses for the coexistence of multiple sexual signals. Although receiver responses to the regularity of barred plumage were not studied here, research on other species has shown that barred plumage can mediate social interactions. We conclude that using barred plumage as a signal of quality helps circumvent the functional compromise between camouflage and communication.

The Distributed Convergence Classifier Using the Finite Difference

The paper presents a novel distributed classifier of the convergence, which allows to detect the conver- gence/the divergence of a distributed converging algo- rithm. Since this classifier is supposed to be primarily applied in wireless sensor networks, its proposal makes provision for the character of these networks. The classifier is based on the mechanism of comparison of the forward finite differences from two consequent iterations. The con- vergence/the divergence is classifiable only in terms of the changes of the inner states of a particular node and there- fore, no message redundancy is required for its proper functionality.

A distributed selectivity-driven search strategy for semi-structured data over DHT-based networks

Distributed Hash Tables (DHTs) are widely used for indexing and locating many types of resources, including semi-structured data modeled as XML documents. A common distributed strategy to process an XML query over a DHT consists in splitting it into a set of simple path queries, and resolving each of them separately. The traffic generated by this strategy grows with the number of paths in the query. To overcome this drawback, an alternative strategy consists in resolving only the sub-query associated with the most selective path, and then submitting the original query to the nodes in the result set. A first goal of this paper is to provide an analytical and experimental study of the two strategies to assess their relative merits in different scenarios. On the basis of this study, we introduce an Adaptive Path Selection (APS) search technique that resolves an XML query in a distributed way by querying either the most selective path or the whole path set, based on the selectivity of the paths in the query. The effective use of APS requires that the querying nodes know in advance the selectivity of all the paths. Addressing this problem is another goal of the paper, which is achieved through: (i) The definition of a space-efficient data structure, the Path Selectivity Table (PST), which given any path, returns an estimate of its selectivity. (ii) The definition of an efficient strategy that builds the PST in a distributed way and propagates it to all nodes in the network with logarithmic performance bounds and without redundant messages. Experimental results show that the PST accurately estimates the path selectivity values, and that the traffic generated by the APS algorithm using PST-estimated selectivity values is comparable to that produced by APS assuming to know the real path selectivity values.