Message Transmission Delay Research Articles

Optimizing Content Dissemination for Real-Time Traffic Management in Large-Scale Internet of Vehicle Systems

As an application of “smart transport” for Internet of Things, Internet of Vehicle (IoV) has emerged as a new research field based on vehicular ad hoc networks (VANETs). With the development of smart vehicles and the integration of sensors, applications of traffic management and road safety in large-scale IoV systems have drawn great attentions. By sensing events occurred on roads, vehicles can broadcast messages to inform others about traffic jams or accidents. However, the store-carry-and-forward transmission pattern may cause a large transmission delay, making the implementation of large-scale traffic management difficult. In this paper, we put forward a feasible solution to minimize the response time for traffic management service, by enabling real-time content dissemination based on heterogeneous network access in IoV systems. We first design a crowdsensing-based system model for large-scale IoV systems. Then, a cluster-based optimization framework is investigated to provide timely responses for traffic management. Specifically, we estimate the message transmission delay by stochastic theory, which can provide a guideline for the next-hop relay selection in our delay-sensitive routing scheme. Furthermore, network performances are evaluated based on two city-road maps, and performance metrics, containing average delivery delay, average delivery ratio, average communication cost, and access ratio, demonstrate the superiority of our system. Finally, we conclude our work and discuss the further work.

Time Barrier-Based Emergency Message Dissemination in Vehicular Ad-hoc Networks

With the advancement in technology and inception of smart vehicles and smart cities, every vehicle can communicate with the other vehicles either directly or through ad-hoc networks. Therefore, such platforms can be utilized to disseminate time-critical information. However, in an ad-hoc situation, information coverage can be restricted in situations, where no relay vehicle is available. Moreover, the critical information must be delivered within a specific period of time; therefore, timely message dissemination is extremely important. The existing data dissemination techniques in VANETs generate a large number of messages through techniques such as broadcast or partial broadcast. Thus, the techniques based on broadcast schemes can cause congestion as all the recipients re-broadcast the message and vehicles receive multiple copies of same messages. Further, re-broadcast can degrade the coverage delivery ratio due to channel congestion. Moreover, the traditional cluster-based approach cannot work efficiently. As clustering schemes add additional delays due to communication with cluster head only. In this paper, we propose a data dissemination technique using a time barrier mechanism to reduce the overhead of messages that can clutter the network. The proposed solution is based on the concept of a super-node to timely disseminate the messages. Moreover, to avoid unnecessary broadcast which can also cause the broadcast storm problem, the time barrier technique is adapted to handle this problem. Thus, only the farthest vehicle rebroadcasts the message which can cover more distance. Therefore, the message can reach the farthest node in less time and thus, improves the coverage and reduces the delay. The proposed scheme is compared with traditional probabilistic approaches. The evaluation section shows the reduction in message overhead, transmission delay, improved coverage, and packet delivery ratio.

EFFICIENCY EVALUATION OF SCHEDULING ALGORITHMS FOR DELAY-SENSITIVE TRAFFIC IN OFDM DOWNLINK

Introduction: Common introduction of industrial control systems based on wireless networks leads to the emergence of a new way of using wireless networks, called the Industrial Internet of Things (IIoT). This framework assumes a large but finite number of users for which you have to provide the transmission of short messages with low delay and limited delay variation. Purpose: Efficiency evaluation of resource allocation algorithms for delay-sensitive traffic in a downlink OFDM channel. Methods: A n OFDM system is presented as a set of M/G/1 queuing systems. A convex optimization problem is introduced, whose solution determines the lower boundary of the average delay of message transmission in delay-sensitive traffic over the set of scheduling algorithms under study. Results: An algorithm is proposed for calculating the lower boundary of the average delay. This algorithm is fed by system parameters: the average message size, the input flow intensity, and the average maximum throughput for each device connected to the base station. Based on these input parameters, the optimization problem is introduced and solved by a numerical method. The solution of the optimization problem determines the lower boundary of the average message transmission delay. Practical relevance : The obtained result can be used by system developers for plan ning and deploying OFDM networks . It can also serve as a reference when developing Ultra- Reliable and Low Latency Communication technology .

BMCGM: A Behavior Economics-Based Message Transmission Cooperation Guarantee Mechanism in Vehicular Ad-hoc NETworks.

Vehicular Ad-hoc NETwork (VANET) is a special mobile ad hoc network that composed of facilities such as vehicle nodes and roadside units. Message transfer among vehicle nodes has been a great challenge due to the network’s highly variable topology and the selfish nature of vehicle nodes. Thus, it is very necessary to propose a mechanism to improve the cooperation among vehicle nodes to guarantee the effective message transmission. Currently, incentive-based cooperation mechanisms are commonly used to encourage nodes to participate in message transmission. Those mechanisms are based on traditional economics and generally assume that the decision-making behavior of nodes is completely independent. Also, the cooperation of nodes depends on whether the cooperation behavior can obtain the higher utility. But researches in behavioral economics have shown that due to the existence of altruistic reciprocity, the behavior of nodes is affected by not only their utility but also the behavioral motives of other nodes, so as to obtain different results from traditional incentive-based mechanisms. Therefore, the paper introduces the reciprocal altruistic from behavioral economics and proposes the reciprocal altruistic factor to reconstruct the utility function of nodes. The reconstructed utility function reflects the interaction of behavioral motives among nodes, which promotes the node’s cooperative behavior. Also, since the Network Formation Game (NFG) is a common mathematical model for studying the interaction and communication links formation among network nodes, hence the paper regards NFG in traditional economics as the research object. A Behavior Economics-based Message Transmission Cooperation Guarantee Mechanism named BMCGM is proposed, which motivates nodes to participate in the message transmission to reduce the transmission delay ratio. The simulation results show that the BMCGM reduces message transmission delay by at least 30.3% compared with the recent representative cooperation transmission mechanism.

Location-assistant content distribution scheme for emergency rescue

In order to optimize the timeliness and pertinence of message delivery in emergency rescue scenarios and improve the service performance of emergency communications network, we propose a location-assistant content distribution scheme based on delay tolerant network. First of all, considering that the movement patterns of rescue teams tend to follow a predetermined course of action, we design a location-based group mobility model. Due to the intermittent network connectivity and variety of emergency service, a content-classification-based publish/subscribe architecture and a GenericSpray routing algorithm based on the prediction of overlap opportunity in spatio-temporal positions are proposed. Furthermore, we also give a cache management strategy based on the content significance. Since location-assistant content distribution scheme can predict the overlap of activity between rescue teams through the course of action, not only can the number of copy forwarding and message delivery delays be significantly reduced but also the priority delivery of important messages can be ensured by message classification. Simulation experiments show that compared with the traditional delay tolerant network routing algorithm and the classic first-in-first-out caching strategy, location-assistant content distribution scheme improves the performance of message delivery rate, transmission delay, and control overhead significantly.

Application-value-awareness cross-layer MAC cooperative game for vehicular networks

In vehicular ad-hoc networks (VANETs), numerous safety related applications have a stringent requirement for the upper latency limit for transmission of messages between vehicles. Thus, it is necessary to design a high-efficiency medium access control (MAC) method that can ensure the allowed upper limit of message delivery delay is satisfied. In this study, we propose the concept of application value (i.e., the value of a conveyed packet), and correlate it with the waiting time of a packet determined by the delay of each concerned message. Subsequently, we design an inter-vehicle cross-layer cooperative game model taking into account the global optimal utility of the participants. Next, we theoretically prove the existence of an equilibrium using a Markov decision process (MDP), and provide a concrete approach to obtain the channel access probability of a node according to the best response method. Finally, we present the results of a partially observable MDP (POMDP) and of the extensive numerical analyses of the performance indicators such as the access delay, throughput, and packet delivery rate (PDR). These are compared with the IEEE 802.11p protocol in saturated and unsaturated states. These comparisons show that the proposed cross-layer MAC cooperative game method guarantees the message transmission delay when the channel is nearly saturated, enabling a successful delivery of the messages within the time limit and providing a strong support to delay-sensitive safety related applications.

Vehicular delay-tolerant networks for smart grid data management using mobile edge computing

With the widespread popularity and usage of ICT around the world, there is increasing interest in replacing the traditional electric grid by the smart grid in the near future. Many smart devices exist in the smart grid environment. These devices may share their data with one another using the ICT-based infrastructure. The analysis of the data generated from various smart devices in the smart grid environment is one of the most challenging tasks to be performed as it varies with respect to parameters such as size, volume, velocity, and variety. The output of the data analysis needs to be transferred to the end users using various networks and smart appliances. But sometimes networks may become overloaded during such data transmissions to various smart devices. Consequently, significant delays may be incurred, which affect the overall performance of any implemented solution in this environment. We investigate the use of VDTNs as one of the solutions for data dissemination to various devices in the smart grid environment using mobile edge computing. VDTNs use the store-and-carry forward mechanism for message dissemination to various smart devices so that delays can be reduced during overloading and congestion situations in the core networks. As vehicles have high mobility, we propose mobile edge network support assisted by the cloud environment to manage the handoff and the processing of large data sets generated by various smart devices in the smart grid environment. In the proposed architecture, most of the computation for making decisions about charging and discharging is done by mobile devices such as vehicles located at the edge of the network (also called mobile edge computing). The computing and communication aspects are explored to analyze the impact of mobile edge computing on performance metrics such as message transmission delay, response time, and throughput to the end users using vehicles as the mobile nodes. Our empirical results demonstrate an improved performance 10-15 percent increase in throughput, 20 percent decrease in response time, and 10 percent decrease in the delay incurred with our proposed solution compared to existing state-ofthe- art solutions in the literature.

A Multi-Hop Broadcast Protocol for Emergency Message Dissemination in Urban Vehicular Ad Hoc Networks

In vehicular ad hoc networks (VANETs), multi-hop wireless broadcast has been considered a promising technology to support safety-related applications that have strict quality-of-service (QoS) requirements such as low latency, high reliability, scalability, etc. However, in the urban transportation environment, the efficiency of multi-hop broadcast is critically challenged by complex road structure, severe channel contention, message redundancy, etc. In this paper, we propose an urban multi-hop broadcast protocol (UMBP) to disseminate emergency messages. To lower emergency message transmission delay and reduce message redundancy, UMBP includes a novel forwarding node selection scheme that utilizes iterative partition, mini-slot, and black-burst to quickly select remote neighboring nodes, and a single forwarding node is successfully chosen by the asynchronous contention among them. Then, bidirectional broadcast, multi-directional broadcast, and directional broadcast are designed according to the positions of the emergency message senders. Specifically, at the first hop, bidirectional broadcast or multi-directional broadcast conducts the forwarding node selection scheme in different directions simultaneously, and a single forwarding node is successfully chosen in each direction. Then, directional broadcast is adopted at each hop in the message propagation direction until the emergency message reaches an intersection area where multi-directional broadcast is performed again, which finally enables the emergency message to cover the target area seamlessly. Analysis and simulation results show that the proposed UMBP significantly improves the performance of multi-hop broadcast in terms of one-hop delay, message propagation speed, and message reception rate.

Conformance Test for IEDs Based on IEC 61850 Communication Protocol

In this paper, a conformance test platform is built for intelligent electronic devices (IEDs) from different manufacturers based on IEC 61850 communication protocol. A conformance test of time delay of message transmission between two IEDs, made by the same or different manufacturers, is performed. The conformance test platform, as well as the test results provide a helpful reference for IEC 61850 implementation.

Weighted dominating set based routing for ad hoc communications in emergency and rescue scenarios

Disasters create emergency situations and the services provided must be coordinated quickly via a communication network. Mobile adhoc networks (MANETs) are suited for ubiquitous communication during emergency rescue operations, since they do not rely on infrastructure. The route discovery process of on-demand routing protocols consumes too much bandwidth due to high routing overhead. Frequent route changes also results in frequent route computation process. Energy efficiency, quick response time, and scalability are equally important for routing in emergency MANETs. In this paper, we propose an energy efficient reactive protocol named Weighted-CDSR for routing in such situations. This protocol selects a subset of network nodes named Maximum Weighted Minimum Connected Dominating Set (MWMCDS) based on weight, which consists of link stability, mobility and energy. The MWMCDS provides the overall network control and data forwarding support. In this protocol, for every two nodes u and v in the network there exists a path between u and v such that all intermediate nodes belong to MWMCDS. Incorporating route stability into routing reduces the frequency of route failures and sustains network operations over an extended period of time. With fewer nodes providing overall network control and data forwarding support, the proposed protocol creates less interference and consumes less energy. The simulation results show that the proposed protocol is superior to other protocols in terms of packet delivery ratio, control message overhead, transmission delay and energy consumption.

Road traffic and geography topology based opportunistic routing for VANETs

The message delivery ratio and transmission delay is affected deeply by road traffic flow in vehicular ad hoc networks (VANETs). An opportunistic routing based on geography and road traffic flow for VANETs (ORRIS) was proposed. ORRIS leverages the knowledge of geography positions, motion vectors and road traffic flows. In order to estimate the traffic flow density, the history of encounter number of the vehicles in the opposite direction is considered in ORRIS. The forwarding decisions are made by distributed vehicles based on the geography topology and the road traffic flow. The real map based simulation results show that ORRIS has a better performance than other algorithms, especially when the road traffic is busy or the traffic flow rates have great differences between roads.

Assessing the influence of selfishness on the system performance of gossip based vehicular networks

In delay tolerant vehicular networks, gossip is an efficient forwarding scheme, which significantly reduces the message transmission overhead while maintaining a relatively high transmission rate in the high mobility vehicular environment. This mechanism requires vehicles as the network nodes to forward messages according to the system-defined gossip probability in a cooperative and selfless way among all the vehicles in the system. However, in the real word vehicular networks, most of the vehicular nodes exhibit selfish and non-collaboration behaviors to reduce the gossip probability in order to save their own energy and other limited resources in the vehicular nodes. In this paper, we study how node selfishness influences the performance of energy-constrained gossip forwarding based vehicular networks. We consider two typical forms of selfishness in the realistic vehicular networks: individual selfishness and social selfishness, and study the networking performance by focusing on the average message transmission delay and mean transmission cost. First, we model the message transmission process with selfish behaviors in the gossip forwarding based delay tolerant vehicular networks using a continuous time Markov chain. Based on this useful model, we derive closed-form formulae for average message transmission delay and mean transmission cost. Then, we give extensive numerical results to analyze the impact of selfishness on system performance of the vehicular networks. The results show that gossip forwarding in delay tolerant vehicular networks is robust to selfish behaviors since even when they increase the message transmission delay, there is a gain on the message transmission cost.

On improving delay performance of IEEE 802.11p vehicular safety communication

In this work, we present the design of an efficient Deterministic medium Access DA for Dedicated Short-Range Communication DSRC vehicular safety communication over IEEE 802.11p, called Vehicular DA VDA. VDA supports two types of safety services emergency and routine safety messages with different priorities and strict requirements on delay, especially for emergency safety messages. VDA processes both types of safety messages to maintain a balance between two conflicting requirements: reducing chances of packets collisions and lowering the transmission delay. VDA allows vehicles to access the wireless medium at selected times with a lower contention than it would otherwise be possible within two-hop neighbourhood with the classical 802.11p EDCA or DCF schemes. Besides, we propose an improvement of VDA called Dynamic VDA opportunities Re-assignment DVR to avoid network performance degradation caused by interference outside the two-hops. Particularly, our scheme provides an efficient adaptive adjustment of the Contention Free Period CFP duration to establish a priority between emergency and routine messages. Simulations show that the VDA scheme, used with 802.11p, clearly outperforms 802.11p alone in high-offered load conditions while bounding the transmission delay of safety messages. Furthermore, beyond two-hops, DVR is able to efficiently tackle the interference phenomenon by reducing losses and delays of safety applications.

Increased Energy Efficiency via Delay-Tolerant Transmissions in Cognitive Radio Networks

We are currently witnessing the emergence of two important trends in wireless networks, namely the increased usage of Internet like application many of them which are delay tolerant and cognitive radio techniques. In this paper, the focus is how to capitalize the delay tolerance of various applications (email, P2P networks, social networking & operating system updates, file transfers) to reduce the energy consumption in cognitive networks. Since it becomes feasible to estimate the Primary Users (PU) connections for the Secondary Users (SU) by contacting a trusted database containing the information of PU traffic, a scheme is proposed that explicitly utilize the distribution of SU traffic loads to provide load-balancing. By modeling a M/M/K/L queuing system, the performance of the SUs competition is analyzed under various traffic blocking thresholds and queuing delays. To this end, the number of SU connection that can be accommodated simultaneously is derived, which as a result optimize the frequency channel utilization. A wide set of numerical investigations reveal how message transmission delays and use of white spaces can reduce the energy consumption without affecting PU traffic.

How Much Delay Has to Be Tolerated in a Mobile Social Network?

Message delivery in a mobile social network (MSN) is difficult due to the fact that the topology of such network is sparse and unstable. Various routing schemes for MSNs were proposed to make the message delivery robust and efficient. However, little research has been conducted to explore how much delay has to be tolerated for the message delivery from the source to the destination. Since the social relationships among nodes are stable during a certain period of time, it is expected that the delay of message delivery in MSNs could be modeled with a probability model. In this paper, we take the first step to address this issue. We firstly extract three routing models from the existing routing schemes for MSNs and then develop the probability models of the message transmission delay for each abstract routing model. The simulation results show that the theoretical models match very well the simulation trace statistics.

Delay-constrained anycast routing problem in WDM networks with wavelength conversions

Anycast routing and wavelength assignment problem has been intensively studied in wavelength-division multiplexing (WDM) networks, however, real-time application where packets have explicit expiration deadlines is not taken into consideration. In a WDM network, each link is associated with limited wavelengths available for channel connections. Data transmission over one wavelength to another requires wavelength conversion, which causes a long delay of message transmission. When the network and the set of anycast routing requests are given, the delay-constrained wavelength conversions anycast routing (DWCAR) problem is to find a set of light-paths, one for each source, for anycasting message to one member of the anycast destination group. The objective is to find a minimum number of wavelength conversions with the constraint that the sum of delays along every path must not exceed a given delay-bound. In this paper, we present a Tabu-search based delay-constrained anycast routing algorithm (TSDA) to solve this NP-complete problem, and compare it to a simple K shortest path based anycast algorithm (KSPA). Simulation results show TSDA achieves an average 40–50% improvement in required wavelength conversions.

About Deterministic and non-Deterministic Vehicular Communications over DSRC/802.11p

In this work, we introduce a priority-aware deterministic access protocol called Vehicular Deterministic Access VDA. VDA is based on 802.11p/DSRC and allows vehicles to access the shared medium in collision-free periods. Particularly, VDA supports two types of safety services emergency and routine safety messages with different priorities and strict requirements on delay. To avoid long delays and high packet collisions, VDA allows vehicles to access the wireless medium at selected times with a lower contention than would otherwise be possible within a two-hop neighborhood by the classical 802.11p Enhanced Distributed Channel Access or Distributed Coordination Function schemes. A non-VDA-enabled vehicle, that is, a vehicle not configured with the optional VDA capability over 802.11p, may start transmitting on the shared channel just before or during the VDA opportunities reserved for vehicles with VDA capabilities. To avoid the aforementioned issues and prevent interfering transmissions from VDA-enabled vehicles and non-VDA-enabled vehicles, we also proposed a novel scheme called extended VDA. We analyzed the impact of several design tradeoffs between the contention free period/contention period dwell time ratios on the performance of safety applications with different priorities for VDA and extended VDA. Simulations show that the proposed schemes clearly outperform the backoff-based schemes currently used by 802.11p in high communication density conditions while bounding the transmission delay of safety messages and increasing the packet reception rate. Copyright © 2012 John Wiley & Sons, Ltd.

On the Performance of TETRA DMO Short Data Service in Railway VANETs

In this paper we present the results of an empirical study investigating the performance of TETRA (TErrestrial Trunked RAdio) in a Vehicular Ad-hoc Network (VANET) for safety related railway traffic applications. The Short Data Service (SDS) of TETRA in the Direct Mode Operation (DMO) allows an infrastructure-less exchange of traffic relevant information between vehicles in range of the communication. The propagation channel in case of such a direct (base station free) communication between railway vehicles underlies specific effects, which are not equivalent to other well known terrestrial mobile scenarios. We will present measurements covering urban, suburban and rural environments along a regional railway network in the south of Bavaria. Beside different operational conditions such as front, rear, and flank approaches of trains, we investigated several topological scenarios on both, single and double track sections along the line. We will also discuss the observed characteristic changes in narrow band signal attenuation and Doppler spectra for passages through forests, hilly areas, stations and a tunnel. We determined statistics for the transmission delay of messages and the message erasure rates for single and multi user access on a single common carrier for different transmission intervals. Finally, the quality of service for the envisaged safety applications is assessed.

Expanding transmission capacity of can systems using dual communication channels with kalman prediction

The controller area network (CAN) protocol is widely used for in-vehicle network (IVN) systems, and many automotive companies also use the CAN in chassis network systems. However, the increasing number of electronic control units (ECUs) dictated by the need for more intelligent and fuel-efficient functions requires an IVN system with a greater transmission capacity and less network delay. Automotive companies have tried several approaches such as segmenting CAN systems and developing time-triggered protocols. This paper presents a practical method for increasing the transmission capacity and reducing the network delay in CAN systems using dual communication channels with a traffic-balancing algorithm based on Kalman prediction to forecast the traffic on each channel and allocate frames to the one that is most appropriate. An experimental testbed using commercial microcontrollers with two or more CAN protocol controllers was used to demonstrate the feasibility of the Kalman traffic-balancing algorithm. Experimental results show that the traffic-balancing CAN system with Kalman prediction reduced the transmission delay of all priority messages compared to that of a simple method, such as a channel-switching CAN, without sacrificing the performance for high-priority messages.

An Novel Message Transmission Delay Model for Disruption Tolerant Networking

An Novel Message Transmission Delay Model for Disruption Tolerant Networking