A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> A new global positioning system (GPS)-based routing protocol for ad hoc networks, called zone-based hierarchical link state (ZHLS) routing protocol, is proposed. In this protocol, the network is divided into nonoverlapping zones. Each node only knows the node connectivity within its zone and the zone connectivity of the whole network. The link state routing is performed on two levels: focal node and global zone levels. Unlike other hierarchical protocols, there is no cluster head in this protocol. The zone level topological information is distributed to all nodes. This "peer-to-peer" manner mitigates traffic bottleneck, avoids single point of failure, and simplifies mobility management. Since only zone ID and node ID of a destination are needed for routing, the route from a source to a destination is adaptable to changing topology. The zone ID of the destination is found by sending one location request to every zone. Simulation results show that our location search scheme generates less overhead than the schemes based on flooding. The results also confirm that the communication overhead for creating and maintaining the topology in the proposed protocol is smaller than that in the flat LSR protocol. This new routing protocol provides a flexible, efficient, and effective approach to accommodate the changing topology in a wireless network environment. <s> BIB001 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> This paper presents a novel routing protocol for wireless ad hoc networks-fisheye state routing (FSR). FSR introduces the notion of multi-level fisheye scope to reduce routing update overhead in large networks. Nodes exchange link state entries with their neighbors with a frequency which depends on distance to destination. From link state entries, nodes construct the topology map of the entire network and compute optimal routes. Simulation experiments show that FSR is a simple, efficient and scalable routing solution in a mobile, ad hoc environment. <s> BIB002 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> We present Greedy Perimeter Stateless Routing (GPSR), a novel routing protocol for wireless datagram networks that uses the positions of routers and a packet's destination to make packet forwarding decisions. GPSR makes greedy forwarding decisions using only information about a router's immediate neighbors in the network topology. When a packet reaches a region where greedy forwarding is impossible, the algorithm recovers by routing around the perimeter of the region. By keeping state only about the local topology, GPSR scales better in per-router state than shortest-path and ad-hoc routing protocols as the number of network destinations increases. Under mobility's frequent topology changes, GPSR can use local topology information to find correct new routes quickly. We describe the GPSR protocol, and use extensive simulation of mobile wireless networks to compare its performance with that of Dynamic Source Routing. Our simulations demonstrate GPSR's scalability on densely deployed wireless networks. <s> BIB003 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> In an ad hoc network, each host assumes the role of a router and relays packets toward final destinations. This paper studies efficient routing mechanisms for packet flooding in ad hoc wireless networks. Because a packet is broadcast to all neighboring nodes, the optimality criteria of wireless network routing are different from that of the wired network routing. We show that the minimum cost flooding tree problem is similar to MCDS (Minimum Connected Dominating Set) problem and prove the NP-completeness of the minimum cost flooding tree problem. Then, we propose two flooding methods: self-pruning and dominant pruning. Both methods utilize the neighbor information to reduce redundant transmissions. Performance analysis shows that both methods perform significantly better than the blind flooding. Especially, dominant pruning performs close to the practically achievable best performance limit. <s> BIB004 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> The capacity of ad hoc wireless networks is constrained by the mutual interference of concurrent transmissions between nodes. We study a model of an ad hoc network where n nodes communicate in random source-destination pairs. These nodes are assumed to be mobile. We examine the per-session throughput for applications with loose delay constraints, such that the topology changes over the time-scale of packet delivery. Under this assumption, the per-user throughput can increase dramatically when nodes are mobile rather than fixed. This improvement can be achieved by exploiting a form of multiuser diversity via packet relaying. <s> BIB005 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> Mobile ad hoc routing protocols allow nodes with wireless adaptors to communicate with one another without any pre-existing network infrastructure. Existing ad hoc routing protocols, while robust to rapidly changing network topology, assume the presence of a connected path from source to destination. Given power limitations, the advent of short-range wireless networks, and the wide physical conditions over which ad hoc networks must be deployed, in some scenarios it is likely that this assumption is invalid. In this work, we develop techniques to deliver messages in the case where there is never a connected path from source to destination or when a network partition exists at the time a message is originated. To this end, we introduce Epidemic Routing, where random pair-wise exchanges of messages among mobile hosts ensure eventual message delivery. The goals of Epidemic Routing are to: i) maximize message delivery rate, ii) minimize message latency, and iii) minimize the total resources consumed in message delivery. Through an implementation in the Monarch simulator, we show that Epidemic Routing achieves eventual delivery of 100% of messages with reasonable aggregate resource consumption in a number of interesting scenarios. <s> BIB006 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> Intermittently connected mobile networks are sparse wireless networks where most of the time there does not exist a complete path from the source to the destination. These networks fall into the general category of Delay Tolerant Networks. There are many real networks that follow this paradigm, for example, wildlife tracking sensor networks, military networks, inter-planetary networks, etc. In this context, conventional routing schemes would fail.To deal with such networks researchers have suggested to use flooding-based routing schemes. While flooding-based schemes have a high probability of delivery, they waste a lot of energy and suffer from severe contention, which can significantly degrade their performance. Furthermore, proposed efforts to significantly reduce the overhead of flooding-based schemes have often be plagued by large delays. With this in mind, we introduce a new routing scheme, called Spray and Wait, that "sprays" a number of copies into the network, and then "waits" till one of these nodes meets the destination.Using theory and simulations we show that Spray and Wait outperforms all existing schemes with respect to both average message delivery delay and number of transmissions per message delivered; its overall performance is close to the optimal scheme. Furthermore, it is highly scalable retaining good performance under a large range of scenarios, unlike other schemes. Finally, it is simple to implement and to optimize in order to achieve given performance goals in practice. <s> BIB007 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> Disruption-tolerant networks (DTNs) attempt to route network messages via intermittently connected nodes. Routing in such environments is difficult because peers have little information about the state of the partitioned network and transfer opportunities between peers are of limited duration. In this paper, we propose MaxProp, a protocol for effective routing of DTN messages. MaxProp is based on prioritizing both the schedule of packets transmitted to other peers and the schedule of packets to be dropped. These priorities are based on the path likelihoods to peers according to historical data and also on several complementary mechanisms, including acknowledgments, a head-start for new packets, and lists of previous intermediaries. Our evaluations show that MaxProp performs better than protocols that have access to an oracle that knows the schedule of meetings between peers. Our evaluations are based on 60 days of traces from a real DTN network we have deployed on 30 buses. Our network, called UMassDieselNet, serves a large geographic area between five colleges. We also evaluate MaxProp on simulated topologies and show it performs well in a wide variety of DTN environments. <s> BIB008 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> The Dynamic Source Routing protocol (DSR) is a simple and efficient routing protocol designed specifically for use in multi-hop wireless ad hoc networks of mobile nodes. DSR allows the network to be completely self-organizing and self-configuring, without the need for any existing network infrastructure or administration. The protocol is composed of the two mechanisms of Route Discovery and Route Maintenance, which work together to allow nodes to discover and maintain source routes to arbitrary destinations in the ad hoc network. The use of source routing allows packet routing to be trivially loop-free, avoids the need for up-to-date routing information in the intermediate nodes through which packets are forwarded, and allows nodes forwarding or overhearing packets to cache the routing information in them for their own future use. All aspects of the protocol operate entirely on-demand, allowing the routing packet overhead of DSR to scale automatically to only that needed to react to changes in the routes currently in use. We have evaluated the operation of DSR through detailed simulation on a variety of movement and communication patterns, and through implementation and significant experimentation in a physical outdoor ad hoc networking testbed we have constructed in Pittsburgh, and have demonstrated the excellent performance of the protocol. In this chapter, we describe the design of DSR and provide a summary of some of our simulation and testbed implementation results for the protocol. <s> BIB009 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> The fundamental component for the success of VANET (vehicular ad hoc networks) applications is routing since it must efficiently handle rapid topology changes and a fragmented network. Current MANET (mobile ad hoc networks) routing protocols fail to fully address these specific needs especially in a city environments (nodes distribution, constrained but high mobility patterns, signal transmissions blocked by obstacles, etc.). In our current work, we propose an inter-vehicle ad-hoc routing protocol called GyTAR (improved greedy traffic aware routing protocol) suitable for city environments. GyTAR consists of two modules: (i) dynamic selection of the junctions through which a packet must pass to reach its destination, and (ii) an improved greedy strategy used to forward packets between two junctions. In this paper, we give detailed description of our approach and present its added value compared to other existing vehicular routing protocols. Simulation results show significant performance improvement in terms of packet delivery ratio, end-to-end delay, and routing overhead. <s> BIB010 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> Intermittently connected mobile networks are wireless networks where most of the time there does not exist a complete path from the source to the destination. There are many real networks that follow this model, for example, wildlife tracking sensor networks, military networks, vehicular ad hoc networks (VANETs), etc. To deal with such networks researchers have suggested to use controlled replication or "spraying " methods that can reduce the overhead of flooding-based schemes by distributing a small number of copies to only a few relays. These relays then "look" for the destination in parallel as they move into the network. Although such schemes can perform well in scenarios with high mobility (e.g. VANETs), they struggle in situations were mobility is slow and correlated in space and/or time. To route messages efficiently in such networks, we propose a scheme that also distributes a small number of copies to few relays. However, each relay can then forward its copy further using a single-copy utility-based scheme, instead of naively waiting to deliver it to the destination itself. This scheme exploits all the advantages of controlled replication, but is also able to identify appropriate forwarding opportunities that could deliver the message faster. Simulation results for traditional mobility models, as well as for a more realistic "community-based" model, indicate that our scheme can reduce the delay of existing spraying techniques up to 20 times in some scenarios <s> BIB011 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> Sensors are now embedded in all sorts of devices (such as phones and PDAs) and attached to many moving things such as robots, vehicles and animals. The collection of data from these mobile sensors presents challenges related to the variability of the topology of the sensor network and the need to limit communication (for energy or bandwidth saving). Fortunately, the data collected, despite considerable, is often delay tolerant and its delivery to the sinks is, in most cases, not time critical. We have devised SCAR, a context aware opportunistic routing protocol which allows efficient routing of sensor data to sinks, through selection of best paths by prediction over movement patterns and current battery level of nodes. In this paper we present the implementation of the protocol in Contiki and validate the approach through the use of the COOJA simulator with mobility traces provided by the ZebraNet Project. We compare the performance with respect to random choice based dissemination. <s> BIB012 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> Because a delay-tolerant network (DTN) can often be partitioned, routing is a challenge. However, routing benefits considerably if one can take advantage of knowledge concerning node mobility. This paper addresses this problem with a generic algorithm based on the use of a high-dimensional Euclidean space, that we call MobySpace, constructed upon nodes' mobility patterns. We provide here an analysis and a large-scale evaluation of routing schemes using MobySpace by replaying real mobility traces. The specific MobySpace evaluated is based on the frequency of visits of nodes to each possible location. We present simulation results for single-copy and multi-copy routing strategies that use MobySpace as a means to route bundles or to control flooding. We show that routing based on MobySpace can achieve good performance compared to a number of common algorithms. <s> BIB013 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> It is widely believed that identifying communities in an ad hoc mobile communications system, such as a pocket switched network, can reduce the amount of traffic created when forwarding messages, but there has not been any empirical evidence available to support this assumption to date. In this paper, we show through use of real experimental human mobility data, how using a small label, identifying users according to their affiliation, can bring a large improvement in forwarding performance, in term of both delivery ratio and cost <s> BIB014 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> Vehicular ad hoc networks (VANETs) allow vehicles to form a self-organized network without the need for permanent infrastructure. As a prerequisite to communication, an efficient route between network nodes must be established, and it must adapt to the rapidly changing topology of vehicles in motion. This is the aim of VANET routing protocols. In this paper, we discuss design factors of VANET routing protocols and present a timeline of the development of the existing greedy routing protocols. Moreover, we classify and characterize the existing greedy routing protocols for VANETs and also provide a qualitative comparison of them. <s> BIB015 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> Multihop data delivery through vehicular ad hoc networks is complicated by the fact that vehicular networks are highly mobile and frequently disconnected. To address this issue, we adopt the idea of carry and forward, where a moving vehicle carries a packet until a new vehicle moves into its vicinity and forwards the packet. Being different from existing carry and forward solutions, we make use of predictable vehicle mobility, which is limited by traffic pattern and road layout. Based on the existing traffic pattern, a vehicle can find the next road to forward the packet to reduce the delay. We propose several vehicle-assisted data delivery (VADD) protocols to forward the packet to the best road with the lowest data-delivery delay. Experimental results show that the proposed VADD protocols outperform existing solutions in terms of packet-delivery ratio, data packet delay, and protocol overhead. Among the proposed VADD protocols, the hybrid probe (H-VADD) protocol has a much better performance. <s> BIB016 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> This paper presents ORWAR, a resource-efficient protocol for opportunistic routing in delay-tolerant networks. Our approach exploits the context of mobile nodes (speed, direction of movement and radio range) to estimate the size of a contact window. This knowledge is exploited to make better forwarding decisions and to minimize the probability of partially transmitted messages. As well as optimizing the use of bandwidth during overloads it helps to reduce energy consumption since partially transmitted messages are useless and waste transmission power. Another feature of the algorithm is the use of a differentiation mechanism based on message utility. This allows allocating more resources for high utility messages. More precisely, messages are replicated in the order of highest utility first, and removed from the buffers in the reverse order. To illustrate the benefit of such a scheme the global accumulated utility is used as a system-wide performance metric. Simulations illustrate the benefit of our model and show that ORWAR provides lower overhead and higher delivery rate, as well as higher accumulated utility compared to a number of well-known algorithms (including Maxprop and SprayAndWait). <s> BIB017 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> We propose behavior-oriented services as a new paradigm of communication in mobile human networks. Our study is motivated by the tight user-network coupling in future mobile societies. In such a paradigm, messages are sent to inferred behavioral profiles, instead of explicit IDs. Our paper provides a systematic framework in providing such services. First, user behavioral profiles are constructed based on traces collected from two large wireless networks, and their spatio-temporal stability is analyzed. The implicit relationship discovered between mobile users could be utilized to provide a service for message delivery and discovery in various network environments. As an example application, we provide a detailed design of such a service in challenged opportunistic network architecture, named CSI. We provide a fully distributed solution using behavioral profile space gradients and small world structures. ::: Our analysis shows that user behavioral profiles are surprisingly stable, i.e., the similarity of the behavioral profile of a user to its future behavioral profile is above 0.8 for two days and 0.75 for one week, and remains above 0.6 for five weeks. The correlation coefficient of the similarity metrics between a user pair at different time instants is above 0.7 for four days, 0.62 for a week, and remains above 0.5 for two weeks. Leveraging such a stability in user behaviors, the CSI service achieves delivery rate very close to the delay-optimal strategy (above 94%), with minimal overhead (less than 84% of the optimal). We believe that this new paradigm will act as an enabler of multiple new services in mobile societies, and is potentially applicable in server-based, heterogeneous or infrastructure-less wireless environments. <s> BIB018 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> Current work in routing protocols for delay and disruption tolerant networks leverage epidemic-style algorithms that trade off injecting many copies of messages into the network for increased probability of message delivery. However, such techniques can cause a large amount of contention in the network, increase overall delays, and drain each mobile node's limited battery supply. We present a new DTN routing algorithm, called Encounter-Based Routing (EBR), which maximizes delivery ratios while minimizing overhead and delay. Furthermore, we present a means of securing EBR against black hole denial- of-service attacks. EBR achieves up to a 40% improvement in message delivery over the current state-of-the-art, as well as achieving up to a 145% increase in goodput. Also, we further show how EBR outperforms other protocols by introduce three new composite metrics that better characterize DTN routing performance. <s> BIB019 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> Routing is one of the most challenging open problems in disruption-tolerant networks (DTNs) because of the short-lived wireless connectivity environment. To deal with this issue, researchers have investigated routing based on the prediction of future contacts, taking advantage of nodes' mobility history. However, most of the previous work focused on the prediction of whether two nodes would have a contact, without considering the time of the contact. This paper proposes predict and relay (PER), an efficient routing algorithm for DTNs, where nodes determine the probability distribution of future contact times and choose a proper next hop in order to improve the end-to-end delivery probability. The algorithm is based on two observations: one is that nodes usually move around a set of well-visited landmark points instead of moving randomly; the other is that node mobility behavior is semi-deterministic and could be predicted once there is sufficient mobility history information. Specifically, our approach employs a time-homogeneous semi-markov process model that describes node mobility as transitions between landmarks. Landmark transition and sojourn time probability distributions are determined from nodes' mobility history. A simulation study shows that this approach improves the delivery ratio and also reduces the delivery latency compared to traditional DTN routing schemes. <s> BIB020 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> Most of the existing research work in mobile ad hoc networking is based on the assumption that a path exists between the sender and the receiver. On the other hand, applications of decentralised mobile systems are often characterised by network partitions. As a consequence delay tolerant networking research has received considerable attention in the recent years as a means to obviate to the gap between ad hoc network research and real applications. In this paper we present the design, implementation and evaluation of the context-aware adaptive routing (CAR) protocol for delay tolerant unicast communication in intermittently connected mobile ad hoc networks. The protocol is based on the idea of exploiting nodes as carriers of messages among network partitions to achieve delivery. The choice of the best carrier is made using Kalman filter based prediction techniques and utility theory. We discuss the implementation of CAR over an opportunistic networking framework, outlining possible applications of the general principles at the basis of the proposed approach. The large scale performance of the CAR protocol are evaluated using simulations based on a social network founded mobility model, a purely random one and real traces from Dartmouth College. <s> BIB021 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> It is a challenging work to develop efficient routing protocols for Delay Tolerant Mobile Sensor Networks (DTMSNs), which have several unique characteristics such as sensor mobility, intermittent connectivity, energy limit, and delay tolerability. In this paper, we propose a new routing protocol called Minimum Expected Delay-based Routing (MEDR) tailored for DTMSNs. MEDR achieves a good routing performance by finding and using the connected paths formed dynamically by mobile sensors. In MEDR, each sensor maintains two important parameters: Minimum Expected Delay (MED) and its expiration time. According to MED, messages will be delivered to the sensor that has at least a connected path with their hosting nodes, and has the shortest expected delay to communication directly with the sink node. Because of the changing network topology, the path is fragile and volatile, so we use the expiration time of MED to indicate the valid time of the path, and avoid wrong transmissions. Simulation results show that the proposed MEDR achieves a higher message delivery ratio with lower transmission overhead and data delivery delay than other DTMSN routing approaches. <s> BIB022 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> The delay tolerant mobile sensor network(DTMSN) is a type of sensor network used for pervasive information gathering.DTMSN distinguishes itself from conventional sensor networks by several unique characteristics such as sensor mobility,loose connectivity,and delay tolerability.Therefore,traditional data gathering methods cannot be applied.In this paper,a novel data gathering method named relative distance-aware data delivery scheme(RDAD) is proposed.RDAD introduces a simple non-GPS method with small overhead to gain the relative distance from a node to sink and then to calculate the node delivery probability which gives a guidance to message transmission.RDAD also employs the message survival time and message maximal replication to decide message's transmission and dropping for minimizing transmission overhead.Simulation results have shown that the proposed RDAD data delivery scheme does not only achieve a relatively long network lifetime but also get the higher message delivery ratio with lower transmission overhead and data delivery delay than other DTMSN data delivering approaches. <s> BIB023 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> Routing protocols for disruption-tolerant networks (DTNs) use a variety of mechanisms, including discovering the meeting probabilities among nodes, packet replication, and network coding. The primary focus of these mechanisms is to increase the likelihood of finding a path with limited information, and so these approaches have only an incidental effect on such routing metrics as maximum or average delivery delay. In this paper, we present rapid, an intentional DTN routing protocol that can optimize a specific routing metric such as the worst-case delivery delay or the fraction of packets that are delivered within a deadline. The key insight is to treat DTN routing as a resource allocation problem that translates the routing metric into per-packet utilities that determine how packets should be replicated in the system. We evaluate rapid rigorously through a prototype deployed over a vehicular DTN testbed of 40 buses and simulations based on real traces. To our knowledge, this is the first paper to report on a routing protocol deployed on a real outdoor DTN. Our results suggest that rapid significantly outperforms existing routing protocols for several metrics. We also show empirically that for small loads, RAPID is within 10% of the optimal performance. <s> BIB024 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> Position-based routing has proven to be well suited for highly dynamic environment such as Vehicular Ad Hoc Networks (VANET) due to its simplicity. Greedy Perimeter Stateless Routing (GPSR) and Greedy Perimeter Coordinator Routing (GPCR) both use greedy algorithms to forward packets by selecting relays with the best progress towards the destination or use a recovery mode in case such solutions fail. These protocols could forward packets efficiently given that the underlying network is fully connected. However, the dynamic nature of vehicular network, such as vehicle density, traffic pattern, and radio obstacles could create unconnected networks partitions. To this end, we propose GeoDTN+Nav, a hybrid geographic routing solution enhancing the standard greedy and recovery modes exploiting the vehicular mobility and on-board vehicular navigation systems to efficiently deliver packets even in partitioned networks. GeoDTN+Nav outperforms standard geographic routing protocols such as GPSR and GPCR because it is able to estimate network partitions and then improves partitions reachability by using a store-carry-forward procedure when necessary. We propose a virtual navigation interface (VNI) to provide generalized route information to optimize such forwarding procedure. We finally evaluate the benefit of our approach first analytically and then with simulations. By using delay tolerant forwarding in sparse networks, GeoDTN+Nav greatly increases the packet delivery ratio of geographic routing protocols and provides comparable routing delay to benchmark DTN algorithms. <s> BIB025 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> A vehicular ad-hoc network (VANET) consists of vehicles that form a network without any additional infrastructure, thus allowing the vehicles to communicate with each other. VANETs have unique characteristics, including high node mobility and rapidly changing network topology. Because of these characteristics, routing algorithms based on greedy forwarding such as greedy perimeter stateless routing (GPSR) are known to be very suitable for a VANET. However, greedy forwarding just selects the node nearest to the destination node as a relay node within its transmission range. This increases the possibility of a local maximum and link loss because of the high mobility of vehicles and the road characteristics in urban areas. Therefore, this paper proposes a reliability-improving position-based routing (RIPR) algorithm to solve those problems. The RIPR algorithm predicts the positions, velocities, and moving directions of vehicles after receiving beacon messages, and estimates information about road characteristics to select the relay node. Thus, it can reduce the possibility of getting a local maximum and link breakage. Simulation results using ns-2 revealed that the proposed routing protocol performs much better than the existing routing protocols based on greedy forwarding. <s> BIB026 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> Research and industries are recently more interesting and attracting to the Vehicular Ad hoc Networks (VANETs) development domain. They contribute to safer and more efficient roads by providing timely and accuracy information to drivers and authorities. Thus, the definition of a quality of service routing protocol for VANETs is one of their challenges. In this paper, we propose QoSBeeVanet, a new multipath quality of service routing protocol adapted for the vehicular ad hoc networks. It is based on ideas of the autonomic bee communication. Simulation results taken with NS2 in realist urban settings were shown that QoSBeeVanet outperforms DSDV and AODV two of the current state-of-the-art protocols, in terms of end-to-end delay, normalized overhead load and packet delivery ratio. <s> BIB027 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> A persisting major challenge in Vehicular Delay- Tolerant Networks (VDTNs) is the delay minimization of data delivery when communicating nodes are stationary, arbitrarily deployed along roadsides and considerably apart that they cannot establish direct communication between each other. A source opportunistically releases bundles of data to cooperating vehicles passing by, hoping that they will successfully deliver them to the intended destination. Several complex strategies that tackle this problem have been proposed in the open literature. Nevertheless, these strategies often implicitly assume complete network knowledge. In this paper, we propose a rather simple Probabilistic Bundle Relay Strategy (PBRS) that relaxes the availability of complete network information. A queuing model is formulated to represent VDTN stationary sources where PBRS is deployed. We introduce the bundle release probability parameter which expresses the likelihood that a bundle is released by the source to a vehicle passing by. The proposed model is studied analytically and theoretical expressions of its characteristic parameters are all derived. In particular, we compute the time it takes to release a head-of-line bundle (referred to as the bundle's service time). Moreover, the model is validated through a simulation study that gauges its merit. The simulation results show that even with partial network knowledge the proposed queueing model can guarantee acceptable bundle delivery delay. <s> BIB028 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> For vehicle users, content distribution through roadside APs is an important complement to that through 3G and other cellular networks. However, the unique features of such access scheme pose many challenges on effectively satisfying vehicles' data request. This paper proposes a cooperative content distribution system for vehicles(CCDSV), based on the network-coding, vehicle-AP contact prediction, and data-prefetching techniques. CCDSV uses network coding to distribute encoded data for the effective sharing of popular contents. CCDSV predicts the vehicle's future contact APs and adaptively prefetches requested data in advance before vehicle's arrival. The proposed system is implemented into ns-2 simulator and demonstrates its effectiveness in terms of throughput, reduced traffic load, and download volume. <s> BIB029 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> In Delay Tolerant Mobile Sensor Networks (DTMSNs) that have the inherent features of intermitted connectivity and frequently changing network topology it is reasonable to utilize multi-replica schemes to improve the data gathering performance. However, most existing multi-replica approaches inject a large amount of message copies into the network to increase the probability of message delivery, which may drain each mobile node’s limited battery supply faster and result in too much contention for the restricted resources of the DTMSN, so a proper data gathering scheme needs a trade off between the number of replica messages and network performance. In this paper, we propose a new data gathering protocol called DRADG (for Distance-aware Replica Adaptive Data Gathering protocol), which economizes network resource consumption through making use of a self-adapting algorithm to cut down the number of redundant replicas of messages, and achieves a good network performance by leveraging the delivery probabilities of the mobile sensors as main routing metrics. Simulation results have shown that the proposed DRADG protocol achieves comparable or higher message delivery ratios at the cost of the much lower transmission overhead than several current DTMSN data gathering schemes. <s> BIB030 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> The increasing penetration of smart devices with networking capability form novel networks. Such networks, also referred as pocket switched networks (PSNs), are intermittently connected and represent a paradigm shift of forwarding data in an ad hoc manner. The social structure and interaction of users of such devices dictate the performance of routing protocols in PSNs. To that end, social information is an essential metric for designing forwarding algorithms for such types of networks. Previous methods relied on building and updating routing tables to cope with dynamic network conditions. On the downside, it has been shown that such approaches end up being cost ineffective due to the partial capture of the transient network behavior. A more promising approach would be to capture the intrinsic characteristics of such networks and utilize them in the design of routing algorithms. In this paper, we exploit two social and structural metrics, namely centrality and community, using real human mobility traces. The contributions of this paper are two-fold. First, we design and evaluate BUBBLE, a novel social-based forwarding algorithm, that utilizes the aforementioned metrics to enhance delivery performance. Second, we empirically show that BUBBLE can substantially improve forwarding performance compared to a number of previously proposed algorithms including the benchmarking history-based PROPHET algorithm, and social-based forwarding SimBet algorithm. <s> BIB031 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> Routing in Delay Tolerant Networks (DTNs) is a challenge due to the fact that the network graph is intermittently connected. However, routing benefits considerably if one can take advantage of knowledge concerning nodes mobility, recent studies have shown that human have location visiting preferences in their daily mobility traces, considering this is a common and stable property of human, we utilize it in the design of routing algorithm for social-oriented DTNs. In this paper, we propose a preference location-based routing strategy (PLBR). We focus on three aspects, according to the longterm behavior, we first provide the approach of acquiring one’s preference locations, then the closeness metric which is used to measure the degree of proximity of any two nodes is proposed, on the basis of that, the data forwarding algorithm is presented. Simulations based on real mobility traces show that compared to other two relevant routing protocols in DTNs, PLBR strategy achieves better tradeoff between the data delivery ratio/delay and the delivery overhead. <s> BIB032 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> Delay-optimal data delivery in Vehicular Intermittently Connected Networks (VICNs) is challenging since vehicular traffic is affected by numerous recurring and completely random events. Some of these events cause breakdowns and jams while others subserve traffic stability. Researchers observed that mobile vehicles might be wisely exploited to connect two isolated, Stationary Roadside Units (SRUs). In this context, the design of effective delay-minimal data relaying strategies is receiving significant attention. However, many existing such schemes either do not adequately model vehicular traffic behaviours or adapt typical Internet packet-like forwarding protocols to VICNs. In contrast, this manuscript presents a concise, yet comprehensive study of vehicular traffic states based on which a "comme-il-faut" vehicular traffic model is established. This model captures the fundamental traffic characteristics and enables the selection of appropriate distributions for vehicular flow and speeds that parallel the realistic measurements made by traffic theorists. These distributions constitute the basis of a novel Probabilistic Bundle Release Scheme with Bulk Bundle Release (PBRS-BBR) that is proposed with the objective to minimize the average bundle delivery delay. An analytical queueing model is formulated to assess the performance of PBRS-BBR under medium-to-light vehicular traffic. Extensive simulations are conducted to prove the model's validity and accuracy. <s> BIB033 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> As an important component of transportation system, public transportation accounts for a considerable proportion in the whole traffic flow. The public transportation vehicles can be categorized into two categories as follows: one with determinate trajectories and schedules such as bus, tramway, and light rail; the other with flexible and variable running paths, such as taxis. In this paper, we firstly present a destination-gathering-based driving path prediction method for taxis, which can make taxis’ driving paths prescient in the initial stage of carrying passengers every time. Compared with ordinary vehicles, public transportation vehicles have such features as long time running on roads and no privacy-protection need, and thus their trajectories can be opened. Through utilizing the features above, we propose a novel public-transportation-assisted data delivery scheme (PTDD) used to improve the performance of data delivery of Vehicular Delay Tolerant Networks (VDTNs). Simulation results based on a real map demonstrate the effectiveness of the proposed scheme. <s> BIB034 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> Efficient data delivery in vehicular sensor networks ::: is still a challenging research issue. Position-based routing ::: protocols have been proven to be more suitable for dynamic ::: vehicular networks or large-scale mobile sensor networks than ::: traditional ad hoc routing protocols. However, position-based ::: routing assumes that intermediate nodes can always be found ::: to set up an end-to-end connection between the source and the ::: destination; otherwise, it suffers from network partitions which ::: are very common in vehicular networks and leads to poor ::: performances. This paper addresses data delivery challenge in ::: the possible intermittently connected vehicular sensor networks ::: by combining position-based forwarding strategy with store-carry-forward routing scheme from delay tolerant networks. The ::: proposed routing method makes use of vehicle driving direction ::: to determine whether holding or forwarding the packet. Experimental ::: results show that the proposed mechanism outperforms ::: existing position-based solutions in terms of packet delivery ratio. <s> BIB035 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> Delay-Tolerant Networks (DTNs) are special types of network environments that are subject to delays and disruptions. Traditional end-to-end routing fails in DTNs due to intermittent connections. We apply the concept of DTN to vehicular environments, and propose a new routing protocol that applies both diversity and accuracy in routing decisions. Our proposed routing has one excellent feature that supports its use for a distributed location discovery service. We evaluate this routing, using a real street map, in terms of different performance aspects. Experimental results show the superiority of this protocol over other existing ones. <s> BIB036 </s> A Survey of Abnormal Traffic Information Detection and Transmission Mechanisms in VSNs <s> (b) Routing Information <s> Vehicular sensor network (VSN) is a promising ::: technology which could be widely applied to monitor the physical ::: world in urban areas. In such a scenario, the efficient data delivery ::: plays a central role. Existing schemes, however, cannot choose ::: an optimal route, since they either ignore the impact of vehicular ::: distribution on connectivity, or make some unreasonable ::: assumptions on vehicular distribution. In this paper, we propose ::: a traffic-aware data delivery scheme (TADS). The basic idea of ::: TADS is to choose intersections to forward packets dynamically ::: as the route from a source to destination based on link quality and ::: remaining Euclidean distance to destination. Specifically, we first ::: present an optimal utility function as the criteria of intersection ::: selection. Besides the packet forwarding through intersections, ::: we also propose an improved geographically greedy routing ::: algorithm for packet forwarding in straightway mode. Moreover, ::: in order to decrease the routing overhead brought by the traffic ::: information gathering, we build a traffic condition prediction ::: model to estimate the link quality. The simulation results show ::: that our TADS outperforms existing works on packet delivery ::: ratio, end-to-end delay, and routing overhead. <s> BIB037
(i) Topology-Based Routing. Generally, the topology-based routing refers to the traditional MANET routing, which define the data forwarding rules based on the link information stored in routing tables. They mainly include the following. (1) Proactive Routing. It requires the node to broadcast and exchange the routing information packets periodically, thereby discover the routing initiatively. In addition, each node has to maintain all the nodes' routing information. To reflect the changes of the network topology, the routing tables also need updating frequently. For the high mobile vehicle nodes in VSNs, the proactive routing will spend too much communication cost. The typical proactive routing protocols include: DSDV  , OLSR BIB015 , and FSR BIB002 . (2) On-Demand Routing. It contains two procedures: routing discovery and routing maintenance. Moreover, their topology and routing tables are built on demand; that is, only when the source node finds that there exists no path to destination node, the routing discovery procedure will be started. The typical ondemand routing protocols include: AODV  , DSR BIB009 , and TORA  . (3) Hybrid Topology Routing. It aims to minimize the routing control overhead of proactive routing and the routing discovery time of on-demand routing. It splits the whole network into two zones: inside zone and outside zone. Then, each node maintains the inside zone routing by the proactive routing and discovers the outside zone routing by the on-demand routing. The typical hybrid routing protocols include: ZRP  and ZHLS BIB001 . (ii) Location-Based Routing. In location-based routing, each node must be aware of its position information, so it can forward data to the optimal neighbor node that is closest to the destination node. However, the optimal neighbor node does not always exist. To solve this problem, lots of protocols are proposed, such as GPSR BIB003 , GyTAR BIB010 , and RIRP BIB026 . But, for the reason that they assume that lots of nodes have the communication opportunity and ignore the issue of the network nonconnectivity, they are more suitable to the high density VSNs environment. (iii) DTN Routing. Due to the high mobility and uneven distribution of vehicles, the network topology is dynamicly changeable and the end-to-end connection is hard to keep in VSNs. Moreover, the low market penetration of DSRC devices leads to more sparse and low network connectivity. To enhance the reliability of information transmission, VSNs widely adopt the DTN (delay tolerant network) routing mechanism. The main idea of DTN routing is store and forward. It can be classified into the following. (1) Knowledge-Based Routing. It utilizes the knowledge information to forward data, such as the link state, history encounter information, movement pattern, and network topology. The common knowledgebased routing methods include the following. (a) QoS-Aware Forwarding. Most of the QoS-aware forwarding mechanisms aim to minimize the information transmission delay. Moreover, the constraint objects are two mobile vehicle nodes or two static roadside units. If the constraint objects are vehicle nodes, the whole network can be seen as a connected graph with weights, where the weight of each edge denotes the transmission delay of each link. To guarantee the QoS performance, the node will take the minimum source-to-destination information transmission delay as the optimal object and find the optimal transmission route by algorithms like Dijsktra. The typical example is the MEDR protocol BIB022 . Additionally, QoSBee BIB027 utilizes the pheromone, produced by bees looking for food, to assist in finding the optimal route, thereby ensure the transmission delay condition. For the delay minimization between roadside units, the probability that the data bundles in queue head could be released to the roadside vehicles is computed. Since the high probability indicates a low transmission delay, the vehicle node with the lowest transmission delay is in charge of forwarding data. The typical examples are PBRS-BBR BIB033 and PBRS BIB028 protocols. (b) Prediction-Aware Forwarding. It mainly utilizes the historical statistics, such as encounter time or frequency, movement trajectory of vehicle nodes, to predict the future encounter probability between the vehicle node and the destination node. The neighbor node with the largest encounter probability will be selected to forward data. While the protocols of PROPHET  , Spray and Focus BIB011 , EBR BIB019 , PER BIB020 , and CCSDV BIB029 use the history encounter information to predict the encounter probability, TMA 8 International Journal of Distributed Sensor Networks  and PTDD BIB034 use the history movement trajectory to predict. (c) Environment-Aware Forwarding. It originates from the CAR routing BIB021 , which is based on the various environmental information to forward data. For example, the SCAR BIB012 is based on the history neighbor perception, the MobySpace BIB013 and VADD BIB016 are both based on the movement pattern perception, the ORWAR BIB017 is based on the link time window perception, the RDAR BIB023 and DRADG BIB030 are based on the distance perception, the Maxprop BIB008 and RAPID BIB024 are based on the buffer space perception, and the TADs BIB037 is based on the traffic pattern and road layout perception. (2) Non Knowledge-Based Routing. It forwards data without any knowledge. Meanwhile, the forwarding behavior is random and blind. The typical routing protocols include flooding BIB004 , epidemic BIB006 , direct transmission BIB005 , and Spray and Wait BIB007 . (3) Social Routing. It forwards data with the social relationships or behaviors of drivers. For instance, LABLE BIB014 , BUBBLE BIB031 , and PepleRank  are proposed based on the social relationship. And PLBR BIB032 , ESPR  , CSI BIB018 , and HARP  are proposed based on the social behaviors. (iv) Hybrid-Style Routing. The hybrid-style routing integrates the topology-based routing, location-based routing, and DTN routing. For instance, the GeoDTN+Nav system BIB025 integrates the navigation information with the DTN routing; the GPSR-DTN system BIB035 integrates the location information with the DTN routing; and the DARCC system BIB036 integrates the geographic information with the encounter information.