Cognitive Radio Vehicular Ad Hoc Networks Research Articles

An adaptive and cooperative MAC protocol for safety applications in cognitive radio enabled vehicular Ad-hoc networks

Rapid broadcast of safety message (sm) is critical for real-time applications in cognitive radio vehicular ad hoc networks (CR-VANETs). The arrival of primary users (PU) and the relative unpredictability of traffic emerge as network bottleneck constraints, resulting in unreliable broadcast services. The requirement is for a Medium Access Control (MAC) protocol that allows for fair contention, is adaptive, and includes a makeup strategy for rebroadcasting failed transmissions. There are intricate tradeoff optimisation relationships in which a value for the contention window that is inadequate will not result in optimal network performance. In this paper, we develop a dynamic contention window backoff mechanism using Karush–Kuhn–Tucker (KKT) conditions that enhances network performance by modifying the backoff time according to traffic density. Then we amalgamate this algorithm with a cooperative makeup strategy to design a novel adaptive and cooperative MAC protocol that is operable in a dynamic CR-VANET paradigm (ACCRV-MAC). A Markov chain decision model characterises the protocol, and Network Simulator -2 analyses various performance parameters. The study reveals that ACCRV-MAC improves throughput by 38.3% and reduces network latency by 49% compared to existing MAC protocols.

Performance analysis of cell-based spectrum handoff in cognitive radio vehicular centralized and ad-hoc networks

Spectrum handoff (SHO) is an essential technique in dynamic spectrum access policy to guarantee seamless and robust service of a cognitive radio. Link maintenance probability (LMP), link failure probability (LFP), service completion probability (SCP), probability mass function (PMF), and expected number of SHOs are key measuring metrics to characterize SHO performances in cognitive radio vehicular centralized network (CR-VCNET) and cognitive radio vehicular ad-hoc network (CR-VANET). In this paper, we develop and model the performance measuring parameters for a non-stationary cognitive user (CU) considering both complete service and incomplete service period under two CR network situations: opportunistic situation (OS or CR-VANET) and negotiated situation (NS or CR-VCNET). This paper analyzes the impact of CU mobility and spectrum hole mobility on various performance measuring metrics to explore the characteristics and performance of the CR networks. This paper also presents the comparison results for expected number of SHOs and SCP of a CU with and without mobility in both CR-VCNET and CR-VANET. The results of performance metrics obtain for a non-stationary CU under the impact of service time distributions are significantly different for CR-VCNETs and CR-VANETs. In addition, we also present Monte-Carlo simulation of LMP, LFP, and probability mass function of SHO for a non-stationary CU to validate the proposed model.

A Survey of Game Theoretical Approach in Cognitive Radio Network and 5G-6G Communications

The development of telecommunications, especially wireless communication, requires data transmission at high speed and wide bandwidth to support 5G-6G communication services. For this reason, it is necessary to have a network with adaptive capabilities in managing and improving performance parameters independently through an intelligent radio network system or better known as Cognitive Radio Network (CRN). The use of CRN in several implementations such as Cognitive Radio Ad Hoc Network (CRAHN), Cognitive Radio Vehicular Ad Hoc Networks (CR-VANET), Intelligent CRN and even 6G-CRN has also been widely used. Another method that is also used to optimize system performance independently is through the Game Theory (GT) approach. Game theory can be implemented on CRN as well as on 5G-6G communications. The use of GT in the CRN system provides improvements in terms of increasing system performance such as reducing interference and bit error rate (BER), increasing throughput and Signal to Interference plus Noise Ratio (SINR), power efficiency, increasing utility and resource capacity and being able to achieve convergence or reach the Nash equilibrium state more rapidly. Meanwhile, the use of GT in 5G-6G communication and other technologies are related to the power control, resource allocation, spectrum sharing, channel estimation, channel selection and Quality of Service (QoS) or Quality of Experience (QoE). In general, the use of GT can help to improve the overall performance of a system.

Spectrum Handoff Aware AODV Routing Protocol for Cognitive Radio Vehicular Ad Hoc Networks

End-to-end application performance and throughput of vehicular cognitive transport control protocol depend on how efficiently the segments (TCP header) are being transmitted from source to destination. One way to enhance the performance of vehicular cognitive TCP protocol is by reducing the packet drops in between the source and destination. In general, packet drops occur in between the source and destination of Cognitive Radio Vehicular Ad Hoc Network (CR-VANET) because of spectrum handoff or cognitive node handoff, or network congestion. In this paper, we focus on enhancing the performance of cognitive TCP protocol through “cognitive AODV routing protocol with the spectrum handoff mechanism.” In the proposed work, channel-route control messages of cognitive AODV routing protocol are updated with the support of spectrum handoff which helps to provide the backup opportunistic channel during PU active and helps to reduce the end-to-end spectrum handoff packet drops. Simulation results reveal that the overall performance of the vehicular cognitive TCP protocol with the proposed spectrum handoff aware cognitive AODV routing protocol is enhanced as compared to the existing cognitive TCP protocol.

Power allocation for cooperative communications in non-orthogonal cognitive radio vehicular ad-hoc networks

To achieve the better system performance for cooperative communication in non-orthogonal cognitive radio vehicular ad-hoc networks (CR-VANETs), this paper investigates the power allocation considering the interference to the main system in a controllable range. We propose a three-slot one-way vehicle system model where the mobile vehicle nodes complete information interaction with the assistance of other independent nodes by borrowing the unused radio spectrum with the primary networks. The end-to-end SNR relationship in overlay and underlay cognitive communication system mode are analyzed by using two forwarding protocol, namely, decode-and-forward (DF) protocol and amplify-and-forward (AF) protocol, respectively. The system outage probability is derived and the optimal power allocation factor is obtained via seeking the minimum value of the approximation of system outage probability. The analytical results have been confirmed by means of Monte Carlo simulations. Simulation results show that the proposed system performance in terms of outage under the optimal power allocation is superior to that under the average power allocation, and is also better than that under other power allocation systems.

Delay-tolerant routing and message scheduling for CR-VANETs

Cognitive radio vehicular ad hoc networks (CR-VANETs) can solve the problem of the limited spectrum resource and improve the vehicle-to-vehicle (V2V) communication efficiency. Nevertheless, the fast moving characteristic of vehicles and the occasional sparse density of vehicles lead to the intermittent CR-VANETs. Recent literature of routing in CR-VANETs focuses on a fully interconnected environment yet fails to address solutions for non-real-time applications. To fill this gap, we propose the delay-tolerant routing and message scheduling (DTRM) schemes for non-real-time applications, aiming to maximize the delivery ratio and decrease the delivery overhead in CR-VANETs. First, we propose a routing scheme that builds a concurrent forwarding set and designs a forwarding strategy. In this set, we select relay candidates by considering both the CR channel availability and the V2V contact duration. Moreover, we evaluate the priority of the relay candidate to provide a reliable forwarding strategy. Second, based on the routing scheme, we propose a message scheduling scheme that combines an optimized-binary-tree replication algorithm and a buffer management policy. The proposed algorithm can spread messages and terminate the replication process quickly. The buffer management policy facilitates the tradeoff between the delivery ratio and the delivery overhead, taking into consideration the node priority, the message tag, and the message remaining time-to-live. Simulation results show that DTRM presents a higher packet delivery ratio and a lower overhead ratio than the counterparts. It presents on average gains of 25.1% and 10.9% in terms of delivery ratio and overhead ratio, respectively, when compared with four CR-VANET routing schemes. It also presents on average gains of 35.6% and 34.1% in terms of delivery ratio and overhead ratio, when compared with three message scheduling schemes.

Single‐channel slotted contention in cognitive radio vehicular networks

Cognitive radio vehicular ad-hoc networks (CR-VANETs) allow the vehicles to exploit the unused channels in their vicinity to fulfil the bandwidth demands of infotainment applications. Existing CR-VANET approaches aim at incorporating spectrum sensing and reporting to the widely used IEEE 802.11p standard developed for VANETs. However, all such approaches were developed for CR-VANETs with low vehicular traffic densities. Applying such approaches at high traffic densities results in long sensing periods, long contention periods with frequent collisions and unnecessary transmissions of sensing information, and variable delays that depend on the vehicular density. In this study, the authors present the single-channel slotted contention ( ( SC ) 2 ) protocol designed for highways with highly dense vehicular traffic. The ( SC ) 2 protocol counters the deficiencies of typical CR-VANETs in high-density networks using three components: random single-channel sensing, slotted contention, and implicit-OR aggregation. The proposed protocol can be easily incorporated with the IEEE 802.11p. Analytic and simulation results show that the proposed protocol increases the CR-VANET throughput and the overall spectrum utilisation while significantly decreasing the radio environment map time in high densities when compared to the conventional IEEE 802.11p protocols.

Expansion of Cluster Head Stability Using Fuzzy in Cognitive Radio CR-VANET

The Vehicular Ad Hoc Network (VANET) plays a vital role in the development of smart cities, especially in ensuring vehicles' safety on roads. However, VANET wireless-based networks face some challenges such as security, stability, communication, and reliability. To resolve these issues, we propose a fuzzy cluster head selection scheme in Cognitive Radio (CR) VANET, which uses the CR technology for the spectrum sensing algorithm. In this technology, the free spectrums of the primary user are utilized by secondary users without any correlation. Moreover, we have considered some input parameters such as vehicles' average velocity, distance, network connectivity level, lane weight and trustworthiness for the fuzzy system based CR VANET in this research. The selected cluster head provides stability and reliability to the cluster compared to the state of art techniques. Extensive experiments were conducted in order to evaluate the effectiveness of the proposed approach. However, simulation results authenticate more stable and secure cluster formation using the proposed fuzzy logic based CR VANET.

Trust management for secure cognitive radio vehicular ad hoc networks

Recently, there are growing interests in cognitive radio vehicular ad hoc networks (CR-VANETs), which is a kind of intelligent cyber-physical systems. In CR-VANETs, there are two main processes: spectrum sensing and data transmission. Although some excellent works have been done to address spectrum sensing security and data transmission security in CR-MANETs, these two important areas have traditionally been addressed separately in the literature. In this paper, we propose to use a common framework to study trust management so as to enhance security for both spectrum sensing and data transmission processes in CR-VANETs. We identify a new attack, named joint spectrum sensing and data transmission (JSSDT) attack, in which an attacker can report fake sensing data in the spectrum sensing process as well as drop packets in the data transmission process. Then, using recent advances in the theory of uncertain reasoning, we propose a unified trust management scheme for both spectrum sensing and data transmission processes in CR-VANETs. In addition, based on the unified trust model, we present a weighted consensus-based spectrum sensing scheme to protect the spectrum sensing process. Moreover, we apply the trust value derived from the unified trust model to enhance the security of the data transmission process in CR-VANETs. Simulation results show the effectiveness of the proposed trust-based security schemes.

Towards low-delay and high-throughput cognitive radio vehicular networks

Abstract Cognitive Radio Vehicular Ad-hoc Networks (CR-VANETs) exploit cognitive radios to allow vehicles to access the unused channels in their radio environment. Thus, CR-VANETs do not only suffer the traditional CR problems, especially spectrum sensing, but also suffer new challenges due to the highly dynamic nature of VANETs. In this paper, we present a low-delay and high-throughput radio environment assessment scheme for CR-VANETs that can be easily incorporated with the IEEE 802.11p standard developed for VANETs. Simulation results show that the proposed scheme significantly reduces the time to get the radio environment map and increases the CR-VANET throughput.

Determining vehicles’ radio transmission range for increasing cognitive radio VANET (CR-VANET) reliability using a trust management system

As a part of an intelligent transportation system, a Vehicular Ad-Hoc Network (VANET) requires reliability by way of an essential need. Timely and accurately delivering safety messages in VANET is one of the reliability issues affected by different factors such as the lack of frequency spectrum as well as nodes’ inabilities or misbehaviors. To overcome spectrum shortage, Cognitive Radio (CR) has been proposed while employing a trust mechanism can lessen any damage caused to reliability by incapable or misbehaver nodes. An effective trust management system can analyze ‘agree’ and ‘disagree’ messages and decide about an event to increase reliability. However, message transmission based on trust assessment imposes an extra decision delay causing a reliability cutback, especially in delay-sensitive safety messages. In this research, an effective trust management system for CR-VANET is proposed and analyzed based on a Birth and Death Process (BDP) model to evaluate the average delay imposed by the decision-making process. The probability of event occurrence is also derived in terms of arrival message rate. Moreover, the minimum and maximum permissible range of radio transmission to reach an acceptable degree of reliability, based on the above analysis, is determined. Our statistical analysis in base of 2k factorial methodology shows that determining the radio transmission range has a major impact on decision-making delay. Using the proposed radio transmission range, simulation results also show that reliability can be improved as well as increasing the accuracy of event detection and reducing decision-making and safety message delivery delays.

Network capacity analysis for cellular based cognitive radio VANET in urban grid scenario

The spectrum scarcity of VANETs (Vehicular Ad hoc Networks) can be alleviated by spectrum sharing technology. We present a framework of CCR-VANETs (Cellular-based Cognitive-radio Vehicular Ad hoc Networks). In CCR-VANETs, cellular network performs as primary network while VANET shares the downlink spectrum of cellular network. We consider a scalable urban grid scenario in which vehicles detect available spectrum holes and opportunistically access them according to a carrier-sensing multiple-access protocol. To restrict vehicles’ interference to primary receivers, we set a square preservation region around each particular street block where an active base station is located. The number of street blocks in the preservation region is calculated with the practical assumption that vehicles only know the locations of primary transmitters. We analyze the aggregate interference power from primary and secondary networks, then derive the lower-bound of downlink capacity for the primary network and lower-bound of V2V (Vehicle-to-Vehicle) channel capacity for the secondary network respectively. The numerical results demonstrate the impacts of different network parameters on inter-networks interference level and network capacities.

A Trust-Based Framework for Increasing MAC Layer Reliability in Cognitive Radio VANETs

Vehicular Ad hoc Networks (VANETs) are introduced to improve the performance of Intelligent Transportation Systems (ITS). As safety is the most important purpose of VANETs, reliability is one of their main necessities. In the other hand, regarding the popularity of VANETs in the future of auto-technologies, the lack of bandwidth in peak traffic hours seems to be one of the most important challenges. For this purpose, utilizing Cognitive Radio (CR) technology in VANETs appears to be a proper candidate. Making the most of CR-VANETS capabilities involves cooperation between the vehicles which in turns necessitates a comprehensive trust management system among them. Considering the concept of reliability in CR-VANETs in this article, employment of trust as a mean of improving reliability is investigated. Classifying the node’s misbehaviors into three categories of selfish, malicious and incapable, a model for evaluating reliability is derived, based on which a trust based framework is presented to improve the reliability of VANET’s transmission media access. Simulation results show that considering cognitive radio and trust together can improve the reliability of VANET and can decrease the number of accidents in peak traffic hours.

Cognitive radio network in vehicular ad hoc network (VANET): A survey

Abstract Cognitive radio network and vehicular ad hoc network (VANET) are recent emerging concepts in wireless networking. Cognitive radio network obtains knowledge of its operational geographical environment to manage sharing of spectrum between primary and secondary users, while VANET shares emergency safety messages among vehicles to ensure safety of users on the road. Cognitive radio network is employed in VANET to ensure the efficient use of spectrum, as well as to support VANET’s deployment. Random increase and decrease of spectrum users, unpredictable nature of VANET, high mobility, varying interference, security, packet scheduling, and priority assignment are the challenges encountered in a typical cognitive VANET environment. This paper provides survey and critical analysis on different challenges of cognitive radio VANET, with discussion on the open issues, challenges, and performance metrics for different cognitive radio VANET applications.

Spectrum-Aware Geographic Routing in Cognitive Vehicular Ad Hoc Network Using a Kalman Filter

We propose a position-based routing protocol for cognitive radio vehicular ad hoc networks (CR-VANETs) using aKalmanfilter algorithm. The protocol first selects an idle channel from among all the channels available to a vehicle while moving on a straight road and then finds the best relay node to deliver the packet to the destination. The selection of a relay node is done by dividing the vehicular transmission range into five regions, and then the source/relay node selects the one that is in the region having a higher preference than other regions. Communication between two vehicles occurs only when both the vehicles are on the same channel. Delay may increase while sensing the channel and selecting the relay node. To reduce the delay, we use aKalmanfilter to predict the future positions of all moving vehicles in the network. We consider vehicle-to-vehicle communication and compare our protocol for different probabilities of primary user being idle. Our proposed protocol shows improvement in both packet delivery ratio and end-to-end delay.