A Multi-Token Sector Antenna Neighbor Discovery Protocol for Directional Ad Hoc Networks

In this paper,we propose a Multi-token Sector Antenna Neighbor Discovery(M-SAND)protocol to enhance the efficiency of neighbor discovery in asynchronous directional ad hoc networks.The central concept of our work involves maintaining multiple tokens across the network.To prevent mutual interference among multi-token holders,we introduce the time and space non-interference theorems.Furthermore,we propose a master-slave strategy between tokens.When the master token holder(MTH)performs the neighbor discovery,it decides which 1-hop neighbor is the next MTH and which 2-hop neighbors can be the new slave token holders(STHs).Using this approach,the MTH and multiple STHs can simultaneously discover their neighbors without causing interference with each other.Building on this foundation,we provide a comprehensive procedure for the M-SAND protocol.We also conduct theoretical analyses on the maximum number of STHs and the lower bound of multi-token generation probability.Finally,simulation results demonstrate the time efficiency of the M-SAND protocol.When compared to the QSAND protocol,which uses only one token,the total neighbor discovery time is reduced by 28% when 6beams and 112 nodes are employed.

Critical Nodes Identification: A Non-Cooperative Method for Unknown Topology Information in Ad Hoc Networks

The foundation of ad hoc networks lies in the guarantee of continuous connectivity.However,critical nodes,whose failure can easily destroy network connectivity,will influence the ad hoc network connectivity significantly.To protect the network efficiently,critical nodes should be identified accurately and rapidly.Unlike existing critical node identification methods for unknown topology that identify critical nodes according to historical information,this paper develops a critical node identification method to relax the prior topology information condition about critical nodes.Specifically,we first deduce a theorem about the minimum communication range for a node through the number of nodes and deployment ranges,and prove the universality of the theorem in a realistic two-dimensional scenario.After that,we analyze the relationship between communication range and degree value for each node and prove that the greater number of nodes within the communication range of a node,the greater degree value of nodes with high probability.Moreover,we develop a novel strategy to improve the accuracy of critical node identification without topology information.Finally,simulation results indicate the proposed strategy can achieve high accuracy and low redundancy while ensuring low time consumption in the scenarios with unknown topology information in ad hoc networks.

Mobility Aware Zone-Based Routing in Vehicle Ad hoc Networks Using Hybrid Metaheuristic Algorithm

Vehicle Ad hoc Networks(VANETs)have high mobility and a rando-mized connection structure,resulting in extremely dynamic behavior.Several challenges,such as frequent connection failures,sustainability,multi-hop data transfer,and data loss,affect the effectiveness of Transmission Control Protocols(TCP)on such wireless ad hoc networks.To avoid the problem,in this paper,mobility-aware zone-based routing in VANET is proposed.To achieve this con-cept,in this paper hybrid optimization algorithm is presented.The hybrid algo-rithm is a combination of Ant colony optimization(ACO)and artificial bee colony optimization(ABC).The proposed hybrid algorithm is designed for the routing process which is transmitting the information from one place to another.The optimal routing process is used to avoid traffic and link failure.Thefitness function is designed based on Link stability and Residual energy.The validation of the proposed algorithm takes solution encoding,fitness calculation,and updat-ing functions.To perform simulation experiments,NS2 simulator software is used.The performance of the proposed approach is analyzed based on different metrics namely,delivery ratio,delay time,throughput,and overhead.The effec-tiveness of the proposed method compared with different algorithms.Compared to other existing VANET algorithms,the hybrid algorithm has proven to be very efficient in terms of packet delivery ratio and delay.

A Secured Message Transmission Protocol for Vehicular Ad Hoc Networks

Vehicular Ad hoc Networks(VANETs)become a very crucial addition in the Intelligent Transportation System(ITS).It is challenging for a VANET system to provide security services and parallelly maintain high throughput by utilizing limited resources.To overcome these challenges,we propose a blockchain-based Secured Cluster-based MAC(SCB-MAC)protocol.The nearby vehicles heading towards the same direction will form a cluster and each of the clusters has its blockchain to store and distribute the safety messages.The message which contains emergency information and requires Strict Delay Requirement(SDR)for transmission are called safety messages(SM).Cluster Members(CMs)sign SMs with their private keys while sending them to the blockchain to confirm authentication,integrity,and confidentiality of the message.A Certificate Authority(CA)is responsible for physical verification,key generation,and privacy preservation of the vehicles.We implemented a test scenario as proof of concept and tested the safety message transmission(SMT)protocol in a real-world platform.Computational and storage overhead analysis shows that the proposed protocol for SMT implements security,authentication,integrity,robustness,non-repudiation,etc.while maintaining the SDR.Messages that are less important compared to the SMs are called non-safety messages(NSM)and vehicles use RTS/CTS mechanism for NSM transmission.Numerical studies show that the proposed NSM transmission method maintains 6 times more throughput,2 times less delay and 125%less Packet Dropping Rate(PDR)than traditional MAC protocols.These results prove that the proposed protocol outperforms the traditional MAC protocols.

Distributed intrusion detection for mobile ad hoc networks

Mobile ad hoc networking （MANET） has become an exciting and important technology in recent years, because of the rapid proliferation of wireless devices. Mobile ad hoc networks is highly vulnerable to attacks due to the open medium, dynamically changing network topology, cooperative algorithms, and lack of centralized monitoring and management point. The traditional way of protecting networks with firewalls and encryption software is no longer sufficient and effective for those features. A distributed intrusion detection approach based on timed automata is given. A cluster-based detection scheme is presented, where periodically a node is elected as the monitor node for a cluster. These monitor nodes can not only make local intrusion detection decisions, but also cooperatively take part in global intrusion detection. And then the timed automata is constructed by the way of manually abstracting the correct behaviours of the node according to the routing protocol of dynamic source routing （DSR）. The monitor nodes can verify the behaviour of every nodes by timed automata, and validly detect real-time attacks without signatures of intrusion or trained data. Compared with the architecture where each node is its own IDS agent, the approach is much more efficient while maintaining the same level of effectiveness. Finally, the intrusion detection method is evaluated through simulation experiments.

Self-Organized Public-Key Management for Mobile Ad Hoc Networks Based on a Bidirectional Trust Model

In traditional networks , the authentication is performed by certificate authoritys（CA）,which can＇t be built in distributed mobile Ad Hoc Networks however. In this pa per, we propose a fully self-organized public key management based on bidirectional trust model without any centralized authority that allows users to generate their public-private key pairs, to issue certificates, and the trust relation spreads rationally according to the truly human relations. In contrast with the traditional self-organized public-key management, the average certificates paths get more short, the authentication passing rate gets more high and the most important is that the bidirectional trust based model satisfys the trust re quirement of hosts better.

Reliable adaptive multicast protocol in wireless Ad hoc networks

In wireless ad hoe network environments, every link is wireless and every node is mobile. Those features make data lost easily as well as multicasting inefficient and unreliable. Moreover, Efficient and reliable multicast in wireless ad hoe network is a difficult issue. It is a major challenge to transmission delays and packet losses due to link changes of a multicast tree at the provision of high delivery ratio for each packet transmission in wireless ad hoe network environment. In this paler, we propose and evaluate Reliable Adaptive Multicast Protocol （RAMP） based on a relay node concept. Relay nodes are placed along the multieast tree. Data recovery is done between relay nodes. RAMP supports a reliable multicasting suitable for mobile ad hoe network by reducing the number of packet retransmissions. We compare RAMP with SRM （Scalable Reliable Multicast）. Simulation results show that the RAMP has high delivery ratio and low end-to-end delay for packet transmsission.

An Energy Based Dynamic AODV Routing Protocol in Wireless Ad Hoc Networks

In recent years,with the rapid development of the Internet and wireless communication technology,wireless Ad hoc networks have received more attention.Due to the limited transmission range and energy of nodes in Ad hoc networks,it is important to establish a reliable and energy-balanced transmission path in Ad hoc networks.This paper proposes an energy-based dynamic routing protocol based on the existing AODV routing protocol,which has the following two aspects of improvement:(1)In the route discovery process,a node selects a suitable route from the minimum energy consumption route and the energy-balanced route designed in this paper according to a“Mark”bit that representing remaining energy of a node.(2)Based on(1),a route interruption update strategy was proposed to restart the route discovery process when node energy was used excessively.Simulation results demonstrate that compared with AODV and other existing routing protocols,proposed algorithm can reduce network energy consumption and balance node energy,thus extending the network lifetime.

Multipath Source Self Repair Routing Algorithm for Mobile Ad Hoc Networks

A multipath source self repair routing (MSSRR) algorithm for mobile ad hoc networks is proposed. By using multiple paths which can be repaired by themselves to transmit packets alternately, the network's load is balanced, the link state in the network can be checked in time, the number of the times the route discovery mechanism starts is decreased. If only one route which will be broken can be used to transmit the packets, the route discovery mechanism is restarted.The algorithm is implemented on the basis of dynamic source routing (DSR). The effect of MSSRR on lifetime of the access from the source to the destination and the overhead is discussed. Compared with the performance of DSR,it can be seen that the algorithm can improve the performance of the network obviously and the overhead almost does not increase if the average hop count is larger.

Adaptive 3D Routing Protocol for Flying Ad Hoc Networks Based on Prediction-Driven Q-Learning

The routing protocols are paramount to guarantee the Quality of Service(QoS)for Flying Ad Hoc Networks(FANETs).However,they still face several challenges owing to high mobility and dynamic topology.This paper mainly focuses on the adaptive routing protocol and proposes a Three Dimensional Q-Learning(3DQ)based routing protocol to guarantee the packet delivery ratio and improve the QoS.In 3DQ routing,we propose a Q-Learning based routing decision scheme,which contains a link-state prediction module and routing decision module.The link-state prediction module allows each Unmanned Aerial Vehicle(UAV)to predict the link-state of Neighboring UAVs(NUs),considering their Three Dimensional mobility and packet arrival.Then,UAV can produce routing decisions with the help of the routing decision module considering the link-state.We evaluate the various performance of 3DQ routing,and simulation results demonstrate that 3DQ can improve packet delivery ratio,goodput and delay of baseline protocol at most 71.36%,89.32%and 83.54%in FANETs over a variety of communication scenarios.

An Ant Colony Algorithm Based Congestion Elusion Routing Strategy for Mobile Ad Hoc Networks

A critical challenge for mobile ad hoc networks is the design of efficient routing protocols which are able to provide high bandwidth utilization and desired fairness in mobile wireless environment without any fixed communication establishments. Although extensive efforts have already been devoted to providing optimization based distributed congestion elusion strategy for efficient bandwidth utilization and fair allocation in both wired and wireless networks,a common assumption therein is the fixed link capacities,which will unfortunately limit the application scope in mobile ad hoc networks where channels keep changing. In this paper,an effective congestion elusion strategy is presented explicitly based on ant colony algorithm for mobile ad hoc networks, which will explore the optimal route between two nodes promptly,meanwhile forecast congestion state of the link. Accordingly,a new path will be found rapidly to have the flow spread around to relieve the congestion degree. Compared with OLSR,the strategy proposed will greatly reduce the packet loss ratio and the average end-to-end delay at the same time,which illustrate that it will make use of networking resource effectively.

Virtual reality mobility model for wireless ad hoc networks

For wireless ad hoc networks simulation, node＇s mobility pattern and traffic pattern are two key elements. A new simulation model is presented based on the virtual reality collision detection algorithm in obstacle environment, and the model uses the path planning method to avoid obstacles and to compute the node＇s moving path. Obstacles also affect node＇s signal propagation. Considering these factors, this study implements the mobility model for wireless ad hoc networks. Simulation results show that the model has a significant impact on the performance of protocols.

BNE-based concurrent transmission considering channel quality and its PSO searching strategy in Ad Hoc networks

The paper proposes a decentralized concurrent transmission strategy in shared channels based on an incomplete information game in Ad Hoc networks.Based on the nodal channel quality,the game can work out a channel gain threshold,which decides the candidates for taking part in the concurrent transmission.The utility formula is made for maximizing the overall throughput based on channel quality variation.For an achievable Bayesian Nash equilibrium（BNE） solution,this paper further prices the selfish players in utility functions for attempting to improve the channel gain one-sidedly.Accordingly,this game allows each node to distributedly decide whether to transmit concurrently with others depending on the Nash equilibrium（NE）.Besides,to make the proposed game practical,this paper next presents an efficient particle swarm optimization（PSO） model to fasten the otherwise very slow convergence procedure due to the large computational complexity.Numerical results show the proposed approach is feasible to increase concurrent transmission opportunities for active nodes and the convergence can be swiftly obtained with a few of iteration times by the proposed PSO algorithm.

An efficient proactive RSA scheme for large-scale ad hoc networks

A previous proactive RSA scheme for large-scale ad hoc network has been shown to be faulty. In this paper, we present a new proactive RSA scheme for ad hoc networks, which includes four protocols： the initial key distribution protocol, the share refreshing protocol, the share distribution protocol, and the signature generation protocol. This scheme has two advantages： the building blocks are secure, and the system is efficient.

A new multi-channel MAC protocol based on CDMA for ad hoc networks

This paper proposes a novel multichannel medium access control （MAC） protocol based on CDMA that improves network performance and reduces collision probability in wireless ad hoc networks. In the scheme, the code channel is divided into common channel, broadcast channel and several data channels. Simulation results show that the proposed protocol can achieve significantly better performance than the IEEE 802.11 standard.

A distributed adaptive multi-hop certification authority schemefor mobile Ad Hoc networks

This paper theoretically analyzes a deficiency of the existing scheme, and proposes a distributed multi-hop certification authority scheme for mobile Ad Hoc networks. In our design, we distribute the certification authority functions through a threshold secret sharing mechanism, in which each node holds a secret share and multiple nodes jointly provide complete services. Certification authority is not limited in a local neighborhood but can be completed within multi-hop location. In addition, we replace broadcast by multicast to improve system performance and reduce communication overhead. This paper resolves some technical problems of ubiquitous certification authority services, and presents a wieldy multi-hop certification authority algorithm. Simulation results confirm the availability and effectiveness of our design.

History-Based Backoff Algorithms for Mobile Ad Hoc Networks

Mobile Ad hoc Network (MANET) is a wireless network consisting of mobile devices (laptops, smart phones, etc.) that move and communicate with each other without the use of any existing network infrastructure or centralized server to avoid collisions which have negative effects on the performance of the network. Access to the shared media is controlled by a Backoff algorithm that is a part of the Media Access Protocol. In this paper, we improve the History Based Probabilistic Backoff (HPPB) algorithm by modifying the increment/decrement behavior of the Contention Window to introduce History Based Increment Backoff (HBIB) algorithm which outperforms HBPB in terms of throughput and end-to-end delay with various numbers of nodes and different traffic loads.

Issues and Challenges in Node Connectivity in Mobile Ad Hoc Networks: A Holistic Review

One of the fundamental properties of an ad hoc network is its connectivity. Maintaining connectivity in wireless networks is extremely difficult due to dynamic changing topology of MANETs. There are several techniques to understand the connectivity level for a given network topology. In this paper, we examine the existing methods and discuss the issues and challenges that are still insurmountable in order to enhance the connectivity properties of wireless multi hop networks.

A New Communication Scheme for Threshold Certificate Authority in Ad Hoc Networks

We present a new approach to reduct the com--munication overhead caused bythreshold cryptography using modified multicast protocol and certificate proxy technology. Servernodes maintain a few multicast groups proactively. A client wanting to updateits certificatemulticasts its request to a server nocks group through its certificate proxy. At periodic intervals,server nodes refresh their shares of the private key of certificate authority using multicast.

Escape probability based routing for ad hoc networks

Routes in an ad hoc network may fail frequently because of node mobility. Stability therefore can be an important element in the design of routing protocols. The node escape probability is introduced to estimate the lifetime and stability of link between neighboring nodes and the escape probability based routing （EPBR） scheme to discover stable routes is proposed. Simulation results show that the EPBR can discover stable routes to reduce the number of route rediscovery, and is applicable for the situation that has highly dynamic network topology with broad area of communication.