Novel Advanced Broadcast Scheme for Efficient Safety Message Collision Alleviation in Vehicular Networks

Safety message broadcasting may cause a broadcast storm in vehicular ad-hoc network without an effective feedback mechanism. In particular, with increasing number of vehicles, serious collisions and incurred long delays are not acceptable for emergency safety messages. In this paper, we proposed an advanced broadcast scheme by the functionality of distributed coordination function and multi-channel operation in dedicated short range communication to decrease collision probability and increase received ratio of safety messages. The proposed scheme can increases safety message transmission efficiency and reduce the latency by delicately designing a rebroadcast probability, choosing the channel and selecting the backoff timer. After broadcasting in the control channel, transmitters return to their original service channel. Then, the vehicles receiving the safety message should inform the others in the same service channel to switch to the control channel for the safety message. Afterwards, the vehicles broadcast the safety message once and go back to the original service channel. This method can inform the other vehicles in different channels to increase the broadcast penetration. The proposed scheme can work without global positioning system (GPS). However, GPS can adapt the rebroadcast probability on hot spots to enhance the efficiency of the proposed scheme. Through detailed simulations, the proposed scheme is shown to be more efficient compared to the existing ones.     

Delay-aware reliable broadcast scheme based on power control for VANETs简

In vehicular Ad-hoc network（VANET）, many multi-hop broadcast schemes are employed to widely propagate the warning messages among vehicles and the key is to dynamically determine the optimal relay vehicle for retransmission. In order to achieve reliable and fast delivery of warning messages, this paper proposes a delay-aware and reliable broadcast protocol（DR-BP） based on transmit power control technique. First, a comprehensive model is derived to evaluate the transmission in vehicle-to-vehicle communications. This model considers the wireless channel fading, transmission delay and retransmissions characters occurring in the physical layer/medium access control（PHY/MAC） layer. Then, a local optimal relay selection mechanism based on the above model is designed. In DR-BP scheme, only the vehicle selected as the optimal relays can forward warning messages and the transmit power is time-varying. Finally, extensive simulations verify the performance of DR-BP under different traffic scenarios. Simulation results show that DR-BP outperforms the traditional slotted 1-persistence（S1P） and flooding scheme in terms of packets delivery ratio and transmission delay.     

A Water-Wave Broadcast Scheme for Emergency Messages in VANET

Vehicular Ad Hoc Network (VANET) is an emerging new technology and a promising platform for the intelligent transportation system. The most important application of VANET is disseminating emergency messages to drivers in case of dangerous events. The effectiveness depends on the design of a broadcast scheme. A simple broadcast scheme encounters many problems such as broadcast storm, connection hole, building shadow, and intersection problems. In this paper, we propose an efficient broadcast scheme that simulates water wave propagation to spread emergency messages. This scheme provides warning services with both space and time constraints. Most existing broadcast schemes provide inadequate strategies for limiting the time period of a warning. We verified the performance of our proposed scheme in a simulated street environment with vehicle movements to show the superiority of this scheme in high broadcast coverage areas.     

A Framework For Handling Local Broadcast Storm Using Probabilistic Data Aggregation In VANET

Data aggregation is used to combine correlated data items from different vehicles before redistributing to other vehicles in the vehicular ad hoc networks (VANET). The number of retransmissions and the communication overhead can be reduced considerably by using aggregation. It is a prerequisite for applications that require periodic dissemination of information into a large region so that, drivers can be informed well in advance and can take alternative route in case of traffic congestion. Dissemination of information to vehicles through broadcasting creates a broadcast storm problem in VANET. In this paper a novel framework is proposed for handling the local broadcast storm problem using probabilistic data aggregation which reduces the bandwidth consumption and hence improves the information dissemination. This system exploits the knowledge base and stores the decisions for aggregation and is based on a flexible and extensible set of criteria. These criteria’s can be application specific and can enable a dynamic fragmentation of the road according to the various application requirements. The framework is evaluated for VANET based traffic information system through simulation for strictly limited bandwidth and local broadcast problem. The results demonstrate that completely structure-free probabilistic data aggregation reduces the bandwidth consumption by eliminating the local broadcast problem.     

Low-Latency Broadcast in Multirate Wireless Mesh Networks

In a multirate wireless network, a node can dynamically adjust its link transmission rate by switching between different modulation schemes. In the current IEEE802.11a/b/g standards, this rate adjustment is defined for unicast traffic only. In this paper, we consider a wireless mesh network (WMN), where a node can dynamically adjust its link-layer multicast rates to its neighbors, and address the problem of realizing low-latency network-wide broadcast in such a mesh. We first show that the multirate broadcast problem is significantly different from the single-rate case. We will then present an algorithm for achieving low-latency broadcast in a multirate mesh which exploits both the wireless multicast advantage and the multirate nature of the network. Simulations based on current IEEE802.11 parameters show that multirate multicast can reduce broadcast latency by 3-5 times compared with using the lowest rate alone. In addition, we show the significance of the product of transmission rate and transmission coverage area in designing multirate WMNs for broadcast     

Rate-Diversity and Resource-Aware Broadcast and Multicast in Multi-rate Wireless Mesh Networks

This paper focuses on the problem of increasing the traffic capacity (volume of admissible traffic) of broadcast and multicast flows in a wireless mesh network (WMN). We study and suggest routing strategies where the process of constructing the forwarding tree considers three distinct features: (a) the ability of individual mesh nodes to perform link-layer broadcasts at multiple rates, (b) the wireless broadcast advantage, whereby a single broadcast transmission covers multiple neighboring receivers and (c) the residual transmission capacity at a WMN node, subject to intereference-based constraints from existing traffic flows in its neighborhood. Our metric of interest is the total number of broadcast and multicast flows that can be admitted into the network, without resulting in unacceptable degradation in metrics such as packet loss and dissemination latency. Our discrete event simulations show that the broadcast tree construction heuristic which takes both transmission rate and residual bandwidth into account out-performs those that do not. Building on our work on resource-aware broadcast tree construction, we propose a resource-aware multicast tree construction algorithm which exploits the multiple link-layer rates, the wireless broadcast advantage and the amount of resources available. Simulation results show that this algorithm performs better than heuristics based on pruning a broadcast tree or shortest path trees.     

ReIDD: reliability-aware intelligent data dissemination protocol for broadcast storm problem in vehicular ad hoc networks

Vehicular ad hoc networks (VANETs) have emerged as fast growing networks with aims to provide safety, and comfort to the onboard passengers. But, in this environment reliable data dissemination to the destination nodes is one of the biggest challenges as there may be a congestion in the network due to blind flooding of messages to their final destination, called as broadcast storm which may lead to the performance degradation with respect to the metric such as-message delivery, reliability and response time. To address this issue, in this paper, we propose a reliability-aware intelligent data dissemination protocol for broadcast storm problem in VANETs. We have solved the above specified problem using game theory concepts in which players, strategy space and decisions with respect to the current state of the system. To reduce the message overhead with respect to the communication cost among the players of the game, in the proposed scheme, messages are routed to the next destination by selecting the most reliable path in an intelligent manner. A coalition game is formulated among the vehicles by considering vehicles as the players in the game. Each player in the game has an initial payoff value based upon the parameters such as-communication range, storage requirements, and computation power. Based upon the payoff value of the players in the game, different coalitions/clusters are formulated among the players in the proposed scheme. Then, the players send the messages to the other vehicles/players within the same coalition which increases the reliability of transmission. In the proposed scheme, messages are unicasted to their final destination in an intelligent manner. Different algorithms are designed for coalition formation, maintenance, and reliability-aware data dissemination. The performance of the proposed scheme is evaluated using various evaluation metrics such as-service time, packet delivery ration, and throughput. The results obtained prove the effectiveness of the proposed scheme as compared to the other state-of-the-art existing schemes.     

多跳无线网络中无需邻节点信息的空间覆盖广播算法

针对多跳无线网络中广播的转发冗余问题,该文提出了一种无需邻节点信息的空间覆盖广播(Space-Covered Broadcast,SCB)算法。SCB算法通过优化转发节点的空间分布达到利用最少数目的转发节点实现对网络空间的覆盖,从而在保证较高送达率的同时明显降低了广播的转发次数。由于无需邻节点信息和网络拓扑信息,SCB算法降低了带宽和存储计算等开销;并且,转发节点的选择由接收节点通过延时转发机制来完成,因而SCB算法能够自动适应信道状况,避免信道变化造成的传输错误。仿真结果表明:该算法在不同的节点密度和网络负载条件下能够明显提高广播的传输效率。     

Identity Based Broadcast Encryption Scheme with Shorter Decryption Keys for Open Networks

In Broadcast Encryption schemes, a sender can broadcast the encrypted message securely in a threatening network to a set of legitimate system users only. In IBE scheme any sender can encrypt the desired message using his/her identity without attaining the public key certificate. Here, we have presented an efficient ID-based broadcast encryption scheme (IBBE) for open networks. In this scheme, desired messages can be broadcasted to any subset of the users by any sender but only authorized receivers are capable in retrieving the encrypted messages. This scheme has shorter decryption keys in comparison with other primitive of IBBE scheme for open networks. Moreover, the proposed scheme intends to achieve the lower cost for computation as well as transmission in comparison to earlier existing IBBE schemes.

     

Network condition and application‐based data adaptive intelligent message routing in vehicular network

Recent advances in intelligent transportation systems enable a broad range of potential applications that significantly improve the vehicle and road safety and facilitate the efficient dissemination of information among the vehicles. To assist the vehicle traffic, message broadcasting is a widely adopted technique for road safety. But efficient message broadcasting is a significant issue, especially in a high network density due to the broadcast storm problem. To solve this issue, several methods are proposed to eliminate the redundant transmission of safety packets. However, they lack in restricting the broadcasting region of safety messages, and the transmissions of safety packets outside the dangerous region, and force the vehicles to unnecessary detours. This paper proposes an adaptive multimode routing protocol, network condition, and application‐based data adaptive intelligent message routing in vehicular network (NetCLEVER) that supports 2 modes of operation such as message broadcasting and intelligent routing. In message broadcasting mode, the NetCLEVER decides the dangerous region of the network by considering the changes of neighbor vehicles velocity, instead of current vehicle velocity, because a vehicle decision in velocity is interdependent with the preceding vehicles. In intelligent routing mode, the NetCLEVER exploits the cuckoo search optimization in routing by taking into account multiple routing factors such as the road topology of intersections and traffic signals and their impact on link stability, which improves the reliability of routing packets significantly. The performance evaluation illustrates that the proposed NetCLEVER improves reliable wireless communication as well as road safety in vehicular ad hoc networks.     

物联网环境中基于车联网与3G网络的跨层安全相关广播业务结构(英文)

As Vehicle Ad Hoc Networks (VANETs) is part of the applications of the Internet of Things (IoT), and Vehicles in VANETs periodically broadcast the beacon message for status advertisement to provide public safety, the impacts of the network parameters on the reliability of broadcast messages are investigated and discussed; meanwhile, a cross-layer safety-critical broadcast service architecture is proposed to obtain an optimized set of packet loss rate and delay based on the Neural Networks (NN) and Back Prop...     

Broadcast scheduling for information distribution

Broadcast data delivery is encountered in many applications where there is a need to disseminate information to a large user community in a wireless asymmetric communication environment. In this paper, we consider the problem of scheduling the data broadcast such that average response time experienced by the users is low. In a push-based system, where the users cannot place requests directly to the server and the broadcast schedule should be determined based solely on the access probabilities, we formulate a deterministic dynamic optimization problem, the solution of which provides the optimal broadcast schedule. Properties of the optimal solution are obtained and then we propose a suboptimal dynamic policy which achieves average response time close to the lower bound. The policy has low complexity, it is adaptive to changing access statistics, and is easily generalizable to multiple broadcast channels. In a pull-based system where the users may place requests about information items directly to the server, the scheduling can be based on the number of pending requests for each item. Suboptimal policies with good performance are obtained in this case as well. Finally, it is demonstrated by a numerical study that as the request generation rate increases, the achievable performance of the pull- and push-based systems becomes almost identical.     

Energy-Aware Broadcast Trees in Wireless Networks

In this paper we address the problem of broadcasting in wireless networks, so that the power consumed by any node is as small as possible. This approach is motivated by the fact that nodes in such networks often use batteries and, hence, it is important to conserve energy individually, so that they remain operational for a long time. We formulate the problem as a lexicographic node power optimization one. The problem is in general NP-complete. We provide an optimal algorithm which runs in polynomial time in certain cases. We also provide a heuristic algorithm whose performance relative to the optimal one is fairly satisfactory. We next show that these algorithms can also be used to solve the problem of broadcasting so that the residual energy of any node after the broadcast process is as large as possible. Finally, we discuss the issues of implementing the above algorithms distributively, as well as their multicast extensions.     

Adaptive intervehicle communication control for cooperative safety systems

Vehicular ad hoc networks play a critical role in enabling important active safety applications such as cooperative collision warning. These active safety applications rely on continuous broadcast of self-information by all vehicles, which allows each vehicle to track all its neighboring cars in real time. The most pressing challenge in such safety-driven communication is to maintain acceptable tracking accuracy while avoiding congestion in the shared channel. In this article we propose a transmission control protocol that adapts communication rate and power based on the dynamics of a vehicular network and safety-driven tracking process. The proposed solution uses a closed-loop control concept and accounts for wireless channel unreliability. Simulation results confirm that if packet generation rate and associated transmission power for safety messages are adjusted in an on-demand and adaptive fashion, robust tracking is possible under various traffic conditions.     

Fast Response PKC-Based Broadcast Authentication in Wireless Sensor Networks

Public Key-based (PKC) approaches have gained popularity in Wireless Sensor Network (WSN) broadcast authentication due to their simpler protocol operations, e.g., no synchronization and higher tolerance to node capture attack compared to symmetric key-based approaches. With PKC??s security strength, a sensor node that authenticates messages before forwarding them can detect a bogus message within the first hop. While this prevents forged traffic from wasting the sensor nodes?? energy, performing PKC operations in the limited computing-power sensor nodes can result in undesirably long message propagation time. At the other extreme, the sensor node can forward messages to other nodes prior to authenticating them. This approach diminishes propagation time with the trade-off of allowing forged messages to propagate through the network. To achieve swift and energy efficient broadcast operation, sensor nodes need to decide wisely when to forward first and when to authenticate first. In this paper, we present two new broadcast authentication schemes, called the key pool scheme and the key chain scheme, to solve this dilemma without any synchronization or periodic key redistribution. Both schemes utilize a Bloom filter and the distribution of secret keys among sensor nodes to create fast and capture-resistant PKC-based broadcast authentication protocols. Our NS-2 simulation results for a 3,000-node WSN confirm that broadcast delays of our protocol are only 46.7% and 39.4% slower than the forwarding-first scheme for the key pool and the key chain scheme respectively. At the same time, both protocols are an order of magnitude faster than the authentication-first scheme. The key pool scheme is able to keep forged message propagation to the minimal even when the majority of the nodes have been captured by the attacker. The key chain scheme has smaller transmission overhead than the key pool scheme at the expense of less resistance to node capturing. Two generic improvements to these schemes are also described. One reduces the marking limit on the Bloom filter vector (BFV), which makes it more difficult for an attacker to forge a BFV for a bogus message. The other limits broadcast forwarding to a spanning tree, which reduces the number of nodes forwarding bogus messages by one to two orders of magnitude depending on the percentage of compromised nodes. The first improvement can be applied to any BFV scheme, while the second is even more generally applicable.     

MIMO广播信道中联合多用户速率和延迟约束调度的研究

该文给出了一种多入多出高斯广播信道中具有延迟约束的多用户无线数据包的传输方案。首先,在信道的QR分解及脏纸编码基础上,通过贪婪算法获取多用户分集与包延迟约束之间的有效结合。其次,将包到达速率、可达服务速率、用户数以及传输天线数构成一优化问题,得到最佳的用户组合及调度周期。最后,在不同用户数及发射天线数情况下对该方案进行了性能仿真,仿真结果表明:在满足包传递最小延迟等待要求的同时,得到了传输容量的最大化。     

Minimum-Energy Broadcasting in Multi-hop Wireless Networks Using a Single Broadcast Tree

In this paper we address the minimum-energy broadcast problem in multi-hop wireless networks, so that all broadcast requests initiated by different source nodes take place on the same broadcast tree. Our approach differs from the most commonly used one where the determination of the broadcast tree depends on the source node, thus resulting in different tree construction processes for different source nodes. Using a single broadcast tree simplifies considerably the tree maintenance problem and allows scaling to larger networks. We first show that, using the same broadcast tree, the total power consumed for broadcasting from a given source node is at most twice the total power consumed for broadcasting from any other source node. We next develop a polynomial-time approximation algorithm for the construction of a single broadcast tree. The performance analysis of the algorithm indicates that the total power consumed for broadcasting from any source node is within 2H(n−1) from the optimal, where n is the number of nodes in the network and H(n) is the harmonic function. This approximation ratio is close to the best achievable bound in polynomial time. We also provide a useful relation between the minimum-energy broadcast problem and the minimum spanning tree, which shows that a minimum spanning tree may be a good candidate in sparsely connected networks. The performance of our algorithm is also evaluated numerically with simulations. A preliminary version of this work appeared in the Proceedings of WiOpt’04: Modeling and Optimization in Mobile, Ad hoc and Wireless Networks, University of Cambridge, UK, March 2004. Ioannis Papdimitriou was fully supported for this work by the Public Benefit Foundation “ALEXANDER S. ONASSIS”, Athens, Greece. Ioannis Papadimitriou was born in Veria, Greece, in 1976. He received his five year Diploma from the Department of Electronic and Computer Engineering, Technical University of Crete (Chania), Greece, in 1999 (graduating 2nd in class). He is currently a postgraduate student - Ph.D. candidate at the Telecommunications division, Department of Electrical and Computer Engineering, Aristotle University of Thessaloniki, Greece. His doctoral thesis deals with the design of wireless ad hoc networks. His research interests include broadcast and multicast communication, energy conservation, routing and topology control protocols, MAC layer and QoS issues. During his studies he has been honored with awards and scholarships by the Technical University of Crete, the Hellenic Telecommunications Organization S.A.(OTE S.A.) and Ericsson Hellas S.A. Mr. Papadimitriou has been a member of the Technical Chamber of Greece (TEE) since March 2000, and he has been supported by the Public Benefit Foundation ALEXANDER S. ONASSIS, Athens, Greece, with a scholarship for his doctoral studies from October 2001 to March 2005. Leonidas Georgiadis received the Diploma degree in electrical engineering from Aristotle University, Thessaloniki, Greece, in 1979, and his M.S. and Ph.D. degrees both in electrical engineering from the University of Connecticut, in 1981 and 1986, respectively. From 1981 to 1983 he was with the Greek army. From 1986 to 1987 he was Research Assistant Professor at the University of Virginia, Charlottesville. In 1987 he joined IBM T.J. Watson Research Center, Yorktown Heights, as a Research Staff Member. Since October 1995, he has been with the Telecommunications Department of Aristotle University, Thessaloniki, Greece. His interests are in the area of wireless networks, high speed networks, distributed systems, routing,scheduling, congestion control, modeling and performance analysis. Prof. Georgiadis is a senior member of IEEE Communications Society. In 1992 he received the IBM Outstanding Innovation Award for his work on goal-oriented workload management for multi-class systems.x     

Toward Broadcast Reliability in Mobile Ad Hoc Networks with Double Coverage

The broadcast operation, as a fundamental service in mobile ad hoc networks (MANETs), is prone to the broadcast storm problem if forwarding nodes are not carefully designated. The objective of reducing broadcast redundancy while still providing high delivery ratio under high transmission error rate is a major challenge in MANETs. In this paper, we propose a simple broadcast algorithm, called double-covered broadcast (DCB), which takes advantage of broadcast redundancy to improve the delivery ratio in an environment that has rather high transmission error rate. Among the 1-hop neighbors of the sender, only selected forwarding nodes retransmit the broadcast message. Forwarding nodes are selected in such a way that 1) the sender's 2-hop neighbors are covered and 2) the sender's 1-hop neighbors are either forwarding nodes or nonforwarding nodes covered by at least two forwarding neighbors. The retransmissions of the forwarding nodes are received by the sender as the confirmation of their reception of the packet. The nonforwarding 1-hop neighbors of the sender do not acknowledge the reception of the broadcast. If the sender does not detect all its forwarding nodes' retransmissions, it resends the packet until the maximum number of retries is reached. Simulation results show that the proposed broadcast algorithm provides good performance under a high transmission error rate environment     

Data Broadcast with Adaptive Network Coding in Heterogeneous Wireless Networks

In this paper, we propose a new data broadcast mechanism with network coding in heterogeneous wireless networks. Our mechanism adaptively clusters the mobile hosts in fewer cells to minimize the bandwidth consumption. In addition, we adaptively code the data according to the data temporarily stored in each mobile host with a distributed manner. Our mechanism allows each delivered message to be coded from only a subset of data to further reduce the number of required messages. We formulate the cell selection and broadcast coding problem with integer programming and prove that the problem is NP-hard. We design a distributed algorithm based on Lagrangean relaxation. Our algorithm needs no server to record the location, queried, and stored information of receivers. Moreover, our algorithm is adaptive to the dynamic group membership, mobility, queried, and stored data of receivers.     

Indexing Techniques for Power Management in Multi-Attribute Data Broadcast

In this paper, we discuss the power conservative indexing techniques for managing multi-attribute data broadcast on wireless channels. These indexing techniques, namely, index tree, signature and hybrid, aim at improving the battery power consumption of mobile clients. By taking into account the broadcast management factors such as clustering and scheduling, these three indexing schemes may significantly reduce tune-in time while maintaining a reasonable access time. Cost models for single and multi-attribute query processing are developed. Our performance evaluation shows that the signature and hybrid methods are superior to the index tree method.