Route selection can greatly affect vehicle fuel consumption and emissions. Finding the most fuel/energy-efficient route is known as the eco-routing problem. Existing eco-routing solutions do not effectively consider the critical traffic signal information and rely on fuel consumption models that may not be sufficiently accurate. To address the eco-routing problem in a signalized traffic network, this paper proposes a graph convolutional network based multi-objective meta-deep Q-learning (GM$^{\bm{2}}$DQL) method. The problem is formulated as dynamic multi-objective Markov decision processes (MOMDP) and is tackled through deep reinforcement learning and meta-learning. We identify that graph convolutional network (GCN) is an efficient and suitable feature representation for a signalized traffic network. GM$^{\bm{2}}$DQL can explore the optimal routes with respect to drivers’ different preferences on saving fuel and travel time. Through GM$^{\bm{2}}$DQL, the agent is trained under a series of learning environments that are characterized by historical vehicle trajectories, fuel consumption data, and traffic signal data in the remote data center. The vehicle requesting eco-routing service can download the model that represents the action value function of the historical dynamic driving conditions. The model in the vehicle can quickly adapt to the most recent driving condition through online one-shot learning and predict the optimal eco-routes for the subsequent unseen driving conditions of the signalized traffic network. Extensive proof-of-concept experiments validate that GM$^{\bm{2}}$DQL can effectively discover optimal eco-routes. It saves up to 71% travel time and 62% fuel, compared to the conventional shortest-path routing strategy that is widely used in navigation systems.

Collaborative spectrum sensing (CSS) in Cognitive Radio based Networks (CRNs) is vulnerable to Spectrum Sensing Data Falsification (SSDF) attack. Many existing defense mechanisms assume the number of malicious users are in minority or the attackers' flip rates are identical and fixed. However, such assumption doesn't hold when some intelligent attacks such as Sybil attack are launched successfully, wherein one dedicated attacker can pretend to be multiple attackers. Besides, most existing approaches adopting "hard decision" approach by identifying the attackers first and ignore their sensing reports in the fusion operation. Thus the overall system performance is degraded since some intelligent attackers' sensing reports are still possible to be genuine. On the other hand, representative existing work using "soft decision" method still cannot distinguish the malicious users and honest users correctly under certain condition. The defense mechanism doesn't perform properly for the case when the distributions of two sensing reports are different but have equal mean and variance. In this paper, we propose a secure fusion strategy which adopts "soft decision" method and can distinguish malicious users and honest users under any distribution of sensing reports using maximum mean discrepancy (MMD). Our proposed CSS scheme is suitable for any general CRN application scenarios. The simulation results show our proposed defense mechanism outperforms the existing works.

Efficient and fair radio resource allocation is essential for wireless networking systems. Most existing fairness-aware dynamic spectrum allocation-based schemes target at instantaneous or short-term resource allocation optimization. However, due to the dynamic nature of wireless networks (in terms of network topologies, traffic demands, qualify-of-service (QoS) requirements, etc.), the resource allocation problem cannot be optimized by only considering instantaneous or short-term resource allocation. In fact, with the fast growing applications of elastic traffic (e.g., video streaming, video conferencing), it is highly desirable to achieve efficient and fair radio resource allocation over a long period of time. In this paper, we propose a long-term fairness-aware dynamic resource allocation mechanism to achieve better system performance (in terms of total network data rate and user fairness). To model the optimal long-term fairness-aware dynamic resource allocation, the stochastic game is adopted to analyze the effect of historical resource allocation on the future network performance. In this scheme, the efficient and fair radio resource allocation for each time slot is optimized with the consideration of the long-term utility. The simulation results show significant performance enhancement in terms of both fairness index and throughput of our mechanism compared to classic dynamic spectrum allocation schemes.

The Common Control Channel (CCC) is foreseen to be adopted to establish and maintain network connections for users in future Cognitive Radio Networks (CRNs). However, the jamming attack can be easily launched to interfere with the CCC of CRNs, and causes the deny-of-service of CRNs. Most of existing anti-jamming approaches are based on the frequency hopping principle with insufficient jamming resilience performance. MIMO based anti-jamming algorithms are effective to improve the jamming resilience performance. However, they are not applicable for the low power cognitive radio networks wherein the user devices are equipped with single antenna, such as cognitive radio sensor network. Observing that relaying strategy will be widely adopted for future CRN systems, we propose a Virtual Multiple Input Multiple Output (VMIMO) based anti-jamming strategy assisted by relay nodes, which proactively mitigates the interference caused by the jamming signal. Simulations show that the bit error rate (BER) of our proposed strategy is at least 10 times lower than that of frequency hopping based approaches.

Abstract The dynamic spectrum access (DSA) paradigm of the cognitive radio (CR) contributes intrinsic security capability to the CR network by hiding information in the unpredictable spectrum access patterns. This paper formalizes the frequency hopping DSA (FH‐DSA)‐based cryptography by introducing the model of dynamic bit (dybit), whose state indicates both the binary value and the DSA strategy. Taking advantage of uncertainty of the dybit state, FH‐based key distribution (FH‐KE) mechanisms are proposed to establish secrets among communication attendants. Based on the group FH‐KE (GKE), a confidentiality‐oriented DSA scheme, GKE‐DSA is developed to realize the FH‐DSA cryptography‐based secure data communication. The GKE‐DSA can conceal the DSA strategy of each communication link from others while limiting the data packet collisions through GKE‐based negotiation. Copyright © 2016 John Wiley & Sons, Ltd.

Collaborative spectrum sensing in Cognitive Radio Networks is vulnerable to Spectrum Sensing Data Falsification (SSDF) attack. Many existing SSDF attack defending algorithms need the assistance of reference sensing devices with high spectrum sensing performance, which are difficult and costly to be implemented in reality. Most of other existing approaches are based on statistic characteristics of sensing information. These approaches assume there is a small fraction of malicious users, and the flip rates of malicious users are fixed and identical. However, some effective attacks such as Sybil attack can be easily launched with which large number of different malicious identities can be generated. To solve these problems, we propose a Fuzzy C-Means clustering based secure fusion strategy. Simulations show this secure fusion strategy outperforms the traditional reputation based approach, at almost any malicious user ratio and varying attack flip rate.

In vehicular ad hoc networks (VANETs), privacy protection makes it challenging to maintain a long-term reputation of any node, while reputation management requires reputation manifestation at risk of easier vehicle tracking. Here, JPRA is proposed to reconcile these challenging conflicts and support the synergistic coexistence of both indispensible schemes in VANETs. JPRA adopts a localized reputation management model where the behavior evaluation, reputation aggregation, and reputation manifestation of each node are collectively performed by itself and its neighbors. In this model, novel algorithms are designed to support secure and efficient reputation management in face of node mobility and privacy protection. Furthermore, a conditional reputation discretization algorithm ensures privacy-preserving reputation manifestation for the honest nodes. Theoretical analysis and simulations show that JPRA can efficiently and synergistically support both schemes in VANETs.

This paper investigates the critical privacy implications of short-time certificates to vehicular ad hoc networks (VANETs). A short-time certificate-based privacy protection scheme, STCP2, is proposed to address such privacy implications. STCP2 features a progressive roadside unit (RSU) deployment algorithm to optimize RSU deployment with cost and application constraints, while providing a minimal privacy assurance to vehicular nodes against the power abuse of VANET authorities. Besides, secure and privacy-preserving pseudonym change procedures enable each node to protect its privacy against both external and internal observers. As such, STCP2 properly protects the privacy of nodes with short-time certificates, as shown by theoretical analysis and simulations.

Vehicular ad hoc networks (VANETs) are emerging as an indispensable platform to collect vehicular sensor data, which can be applied to improve traffic efficiency and support numerous promising commercial applications. However, it is challenging to efficiently collect these data without overloading the network. In this paper, a novel scheme, compressive sensing based data collection (CS-DC), is proposed to efficiently collect spatially correlated data in VANETs. CS-DC is able to efficiently reduce communication overhead with low computation and less communication control. To achieve high cluster stability in CS-DC, the distance and mobility based clustering protocol (DIMOC) is proposed to support reliable data transmissions among neighboring nodes. Furthermore, the compressive sensing (CS) theory is applied to efficiently compress in-network data and accurately recover original data. Simulation results show that the CS-DC scheme significantly improves the efficiency, scalability and reliability of data collection in VANETs.

Allowing commercial service providers (SPs) to promote their businesses, ad dissemination in vehicular ad hoc networks (VANETs) shows great application potential. In this paper, a VANET-based Ambient Ad-Dissemination scheme (VAAD) is proposed to support secure ad disseminations with pragmatic cost and effect control. VAAD provides an incentive-centered architecture for the involved parties to trade off their conflicting requirements regarding ad dissemination. Given realistic advertising effect and cost requirements of an SP, VAAD adopts a distance-based gradient ad dissemination algorithm to maximize the achievable ad effect by emulating the ad-posting patterns in the physical world. To facilitate vehicular nodes' participation in VAAD, efficient, secure, and privacy-preserving incentive cash-in is ensured to support financial transactions in VAAD. Thus, with proper cost and effect control, VAAD is a novel and comprehensive solution to secure ad dissemination in VANETs.

Privacy protection and reputation management, both indispensible to Vehicular Ad Hoc Networks (VANETs), impose conflicting requirements: privacy protection makes it challenging to maintain the reputation history of any node; reputation management requires real-time reputation manifestation at risk of easier vehicle tracking. Here, a novel Joint Privacy and Reputation Assurance (JPRA) scheme is proposed to solve these conflicting requirements. To make reputation aggregation secure and efficient in face of high node mobility and privacy protection, JPRA adopts a localized reputation management approach. A reputation relay procedure ensures that the complete reputation information of any node is always maintained by itself and its 1-hop neighbors in face of network topology changes. Neighbor-assisted reputation update, with partially blind signature, allows each node to securely update its reputation without harming its privacy in JPRA. Eventually, to make reputation manifestation privacy-preserving, a conditional reputation discretization algorithm is proposed to allow the honest nodes to manifest a common reputation value. Analysis and simulations show that JPRA efficiently and synergistically supports the coexistence of reputation schemes and privacy schemes in VANETs.

Abstract Driven by road safety applications and commercial applications, verification of messages' content integrity and authenticity in vehicularad hocnetworks (VANETs) is indispensable. However, due to numerous message exchanges in VANETs, message verification often leads to excessive resource consumption and even resource depletion in vehicular nodes. To tackle the scalability issue, a novel resource‐aware message verification (RAMV) scheme is proposed in this paper. With application specific differentiation of the messages to better support road safety applications, RAMV streamlines the existing message verification schemes to keep their resource consumption within the preset resource budget. Meanwhile, the common security requirements for message verification are all properly met by RAMV. Enabling resource‐aware, safety‐upholding, and secure message verification, RAMV is especially appealing to the forthcoming massive deployment of VANETs. Copyright © 2011 John Wiley & Sons, Ltd.

The 12 papers in this special issue focus on exploiting wireless communication technologies in vehicular traffic networks.

End-to-end delay is critical for the real-time safety message delivery in Vehicular Ad Hoc Networks (VANETs). In this paper, we present an analytical model to evaluate the impact of transmission range on the end-to-end delay in 802.11p-based VANETs. Compared with the previous works, our model derives a concise expression of the transmission delay in saturated networks, and obtains the service rate of non-saturated networks with novel methodology. To the best of our knowledge, it is the first complete analytical model that reveals the significant end-to-end delay difference between saturation and non-saturation cases.

In VANETs, message aggregation is crucial to reduce information redundancy and communication overhead. In addition, it can effectively decrease the information inaccuracy from the on-board sensors. In this paper, we propose a novel scheme, event driven structure-less message aggregation (SLMA), for safety-relevant VANET applications. The key motive of SLMA is to reliably and efficiently improve information accuracy and reduce communication overhead with limited delay at the same time. To our best knowledge, this is the first paper to address these goals of message aggregation simultaneously in VANETs. Using multiple level parallel fusion model to provide high reliability, the structure-less aggregation framework eliminates packet exchanges for aggregation structure formation and maintenance. Bayesian fusion algorithm is adopted to effectively achieve precise event detection on the road. Simulation results show that SLMA scheme efficiently reduces the communication overhead with reasonable delay. Meanwhile, it can greatly improve information accuracy.

The paradigm of dynamic spectrum access, an intrinsic characteristic of the cognitive radio network (CRN), embraces new opportunity for protecting the privacy of communication content through random channel hopping patterns, which are hard to follow by adversaries. Different from conventional DSA where each active CR user only accesses the spectrum once, the confidentiality driven DSA requires every active user to hop over multiple channels during one transmission session. Hence the DSA process is modeled as a fractional coloring process. By artfully converting two-dimensional color to one-dimensional color through vertex expansion, a Latin square (LS) based DSA is proposed, with confidentiality requirements embedded. Theoretic analysis and simulation results verify the feasibility of the DSA based cryptography and illustrates how confidentiality requirement affects the spectrum utilization efficiency.

Dynamic transmission power based dynamic spectrum allocation (DSA) schemes are extensively adopted in cognitive ratio (CR) networks due to their flexible spectrum access strategies to improve spectrum utility. However such DSAs suffer from high sensitivity to the environment change. Based on the protocol model of wireless communications, a notion of interference threshold (IT) is introduced into the DSA model such that the intricate interactions among CRs can be decoupled and CRs' adaptations only affect the local area. With IT modeling, CRs' strategy profile number turns into finite such that an exhaustive search based IT DSA (ES-IT DSA) scheme is feasible to enumerate all strategy profiles for finding the optimal one. To address the scalability issue in ES-IT-DSA, a suboptimal RGF-IT DSA is developed in virtue of restricted growth function theory. Simulation results concur that the IT based DSA algorithms can keep high spectrum utility while achieving simplicity.

In Vehicular Ad Hoc Networks (VANETs), the massive messages are periodically broadcasted by each node and need to be processed by each receiver. Due to their enormous quantity, message verification in this context threatens excessive resource consumption for VANET nodes. Thus, in this paper a novel Resource-Aware Message Verification (RAMV) scheme is proposed to efficiently and securely verify the massive messages in VANETs. Streamlining the existing message verification schemes, RAMV keeps their resource consumption under control in face of massive messages exchanges. Meanwhile, it also ensures that the security requirements for message verification are all properly met, endorsed by both the theoretical analysis and simulation results.

Abstract Due to the unique features of mobilead hocnetworks (MANETs), traditional wired anonymous protocols cannot be directly adopted in MANETs. On the other hand, skillful as they are, existing MANET anonymous routing protocols are often inherited from traditional routing protocols by modifying the content of routing packets of the baseline MANET routing protocols, which causes themselves subjected to certain inherent defects. This paper proposes a novel anonymous on‐demand source routing (AODSR) protocol, which is a scalable distributed solution to achieve sender, receiver, and sender–receiver relation anonymity in MANETs. In AODSR, the route discovery process is not controlled by the initiator/target node, but controlled by a series of random residual‐hop numbers. This not only eliminates different protocol behaviors between the initiator/target node and intermediate nodes, but also avoids the flooding of routing packets. With the aid of the ‘buddy’ group strategy, the anonymity is further reinforced. Based on our security analysis, the peculiar reachability attack caused by the broadcast nature of wireless networks and the shielding attack caused by the hidden‐terminal problem, which are often ignored by existing anonymous MANET routing protocols, are also countered against by AODSR. Theoretical analysis and simulation shows that AODSR achieves high degree of anonymity while requiring low computational complexity and communication overhead. Copyright © 2008 John Wiley & Sons, Ltd.

In vehicular ad hoc networks (VANETs), it is vital to ensure that tampered data packets, especially safety-related ones, are detected and stopped from further propagation. To this end, we propose a novel scheme, autonomous watchdog formation enabled by 2-hop neighborhood awareness (AWF-NA), to ensure nodes automatically functioning as watchdogs to monitor the behaviors of the relaying nodes. Unlike existing schemes [1-4], it aims to detect and react at each hop, and stop any tampered packet from further propagation in spite of dishonest watchdogs and relaying nodes. At each hop, the neighbors of the relaying node and the receiver node autonomously select eligible watchdogs among themselves based on local information provided by 2-hop neighborhood awareness. With 2-hop neighborhood awareness each node knows all the neighbors within its 2 hops, which provides it with necessary information to act according to the heuristic rules in AWF-NA. Induction-based proof shows that AWF-NA can detect all potential attacks of data packet tampering. Theoretical analysis indicates that it achieves good balance of desirable performance and authentic packet relaying.

Robust multi-hop message dissemination in Vehicular Ad hoc Networks (VANETs) is challenging due to the high mobility and frequent partitioning. In this paper, we propose a novel scheme referred as the relative position based message dissemination (RPB-MD), to robustly disseminate messages in VANETs. The relative position based (RPB) addressing model is proposed to define the intended receivers without requiring exterior location service. To achieve robust message dissemination with vehicular traffic independency, RPB-MD adopts the directional greedy broadcast routing approach to forward messages based on position and direction information. The performance of the proposed scheme is evaluated through simulations. Simulation results show that RPB-MD achieves high delivery ratio, limited overhead and reasonable delay.

The game theoretic dynamic spectrum allocation (DSA) technique is an efficient approach to coordinate the cognitive radios to share the spectrum. However, existing game based DSA algorithms lack a platform to support the game process. On the other hand, existing medium access control (MAC) protocols for cognitive radio (CR) networks do not fully utilize the adaptability and intelligence of the cognitive radio (CR) to achieve efficient spectrum utilization, let alone fairness and QoS support. Therefore it is necessary to develop a DSA-driven MAC protocol with the game theoretic DSA embedded into the MAC layer. In this paper, based on the analysis of challenges for the game theoretic DSA in realistic applications, we conclude that a unified game theoretic DSA-driven MAC framework should constitute of four integral components: 1)DSA algorithm, which derives the steady strategy of each radio to guide the channel access for data communication; 2) negotiation mechanism, which coordinates game players to exchange game information and update their strategies in the right game timing; 3) clustering algorithm, which limits the negotiation of game players in one cluster to solve the scalability issue; 4) cluster based collision avoidance mechanism, which is to avoid collisions among negotiations in different clusters. Subsequently, we design each component to construct an effective DSA-driven MAC framework with low cost. Our proposed game theoretic DSA- driven MAC framework can fulfill the merits of game theoretic DSA algorithms including high spectrum utilization, collision- free channel access for data communication, QoS and fairness support. Through simulations, the merits of the DSA-driven MAC framework are demonstrated.

To enable real-time and robust message delivery, the highly mobile vehicular ad hoc networks (VANETs) call for comprehensive investigation on the dynamic power control effects on the real-time and robust communications. Ideally, by adjusting transmission power adaptively, VANET nodes may agilely cope with the segmentation problem at light vehicular traffic and with the limited system capacity problem at high traffic load. In this paper, we propose a delay-bounded dynamic interactive power control (DB-DIPC) module which is a fully distributed and proactive approach, wherein neighboring nodes periodically and interactively reach each other via power adjustment to maintain run-time connectivity. DB-DIPC algorithm is distributed, asynchronous, fast converging, and capable of interactive learning and calibrating over multiple iterations. With DB-DIPC, the transmission powers of VANET nodes are verified iteratively and interactively by the neighbor vehicles at run-time, which consequently ensures that the prompt 1-op neighbor connectivity to adapt the high VANET dynamics. Our analytical and simulation studies confirm these salient features of the proposed DB-DIPC mechanism.

As one special case of the mobile ad hoc networks (MANETs), vehicular ad hoc network (VANET) is featured for its extremely high mobility and constantly changing topology. As a fully distributed network, VANET can work properly only if all the participating vehicles cooperate well during communications. However, lacking centralized coordinators, individual vehicle might be uncooperative for its own benefits. To promote node cooperation and to protect VANET packets during propagation, this paper proposes a dynamic trust-token (DTT) based cooperation enhancement mechanism. DTT utilizes both symmetric and asymmetric cryptography mechanisms to protect packet integrity, and applies neighborhood WatchDog to generate trust token based on instant performance to verify packet correctness. As a result, cooperation among VANET nodes during packet disseminations could be achieved and packet delivery could be well-protected. Performance analysis shows that the latency degradation of the proposed DTT mechanism is negligible.

Providing satisfactory security services in mobile ad hoc network (MANET) is indispensable to their mission critical applications; however, often a highly secure mechanism inevitably consumes a rather large amount of system resources, which in turn may unintentionally cause a security provisioning denial-of-service (SPDoS) attack. To avoid SPDoS attack, a framework is presented to design a resource-aware self-adaptive network security provisioning scheme for the resource constraint MANET. With the support of the offline optimal secure protocol selection module and the online self-adaptive security control module, the framework is capable of deploying different combinations of secure protocols to satisfy different security needs at different conditions for different applications. Consequently, the proposed self-adaptive security provisioning achieves the maximum overall network security services and network performance services, without causing the SPDoS attack. Moreover, it provides additional security capability via security services hopping

Vehicular ad hoc networks (VANETs) will play a vital role in reducing the number of road accidents and fatalities as well as vehicular traffic optimization. Though an instance of mobile ad hoc networks (MANETs), the highly mobile and dynamic environment of VANET introduces new research challenges. To quickly adapt to the highly mobile and constantly changing topology and still meet the desired application requirements, it is vital for the VANET media access control (MAC) protocol guarantees wireless channel access with minimal delay and minimal exchange of control messages. This paper proposes an innovative relative-position-based MAC Nucleus (RPB- MACn). By combining the dedicated communication channel pair and the dedicated directional antenna associated to the relative position of vehicles, a conceptually contention-free RPB-MACn mechanism for VANET is realized (when coupling with dynamic power control mechanism). Consequently, RPB-MACn can meet all the key requirements of the MAC protocol in a VANET system.

Ubiquitous wireless networking calls for efficient dynamic spectrum allocation (DSA) among heterogeneous users with diverse transmission types and bandwidth demands. To meet user-specific quality-of-service (QoS) requirements, the power and spectrum allocated to each user should lie inside a bounded region in order to be meaningful for the targeted application. Most existing DSA methods aim at enhancing the total system utility. As such, spectrum wastage may arise when the system-wise optimal allocation falls outside the desired region for QoS provisioning. The goal of this paper is to develop QoS-aware distributed DSA schemes using the game-theoretic approach. We derive DSA solutions that respect QoS and avoid naively boosting or sacrificing some users' utilities to maximize the network spectrum utilization. Specifically, we propose two game-theoretic DSA techniques: one resorts to proper scaling of the transmission power according to each user's useful utility range, and the other embeds the QoS factor into the utility function used for dynamic gaming. In addition, we introduce two new metrics to evaluate DSA schemes from a practical QoS perspective, namely "system useful utility" and "fraction of QoS satisfied users." Simulations confirm that the proposed DSA techniques outperform existing QoS-blind game models in terms of spectrum sharing efficiency in heterogeneous networks.

In this paper, we first propose almost optimal sequential aggregate signatures in the simulation-based paradigm. We then provide an immediate application of the new primitive to construct compact routing discovery protocols

In this paper, a novel system level methodology for evaluating functionalities of network systems within general security model is introduced and formalized. We first decompose the entire system into a collection of subsystems each associated with a functionality. Thereafter, a new model for evaluating security properties of individual subsystem is built, which intends to implement a functionality by allowing an adversary to learn information and obtain knowledge from the correspondent subsystem via oracle queries. We further define evaluation and security metrics for security qualifications which is shown to be complete and robust within our model

One of the most important issues in sensor enabled emergency applications is the QoS provisioning. Wireless LANs plays critical role in providing anywhere and anytime connectivity for many sensor enabled emergency applications. This paper addresses the issue of provisioning QoS over the wireless channel between the sensor enabled emergency application and the wireless access points (e.g., wireless hotspots in various locations). Unlike traditional QoS provisioning which supports voice and data applications, resulted by the extremely rare events which lack the predictability, it is not trivial to provide adequate QoS support for the emergency data traffic with strong erratic nature. In this paper, we first investigated several potential alternative schemes to support QoS in emergency applications. An express dual channel (EDC) based QoS provisioning approach is then proposed. The proposed mechanism is not only simple and efficient, but also results in the minimum delay for the erratic emergency data traffic. Simulation results show the proposed EDC based solution provides satisfactory QoS for emergency applications.

Providing satisfactory security services in mobile ad hoc networks (MANET) is indispensable for mission critical applications; however, often a highly secure mechanism inevitably consumes a rather large amount of system resources, which in turn may unintentionally cause a security provisioning denial of service (SPDoS) attack. The scheme proposed in this paper sets out a framework to solve this problem by designing a resource-aware self-adaptive network security provisioning scheme. With the support of the offline optimal secure protocol selection module and the online self-adaptive security control module, the framework is capable of deploying different combinations of secure protocols to satisfy different security needs in different conditions for different applications. Consequently, the proposed self-adaptive security provisioning achieves the maximum overall network security services and network performance services, without causing an SPDoS attack. Moreover, it provides additional security capability via security service hopping.