Earticle

Mobile nodes must be managed efficiently for the Internet connectivity of mobile ad hoc networks. The tree-based mobility management approach is highly dependable in that mobile nodes register with Internet gateway along tree paths from itself up to a gateway without using flooding. However, it is costly to resume on-going communication if a node belonging to an active path loses its connectivity to its parent. In this paper, we introduce a new approach in which a node maintains multiple parents whenever possible. A mobile node can still retain its upstream path to a gateway even though it loses connectivity to one of its parents. The new approach is evaluated against the tree-based method by resorting to simulation. The result shows that the new method outperforms the tree-based approach and also is very robust against the change of topology.

To improve traffic safety in intelligent transportation systems, vehicles formed by vehicular ad-hoc networks (VANETs) conventionally disseminate warning messages to their nearby vehicles as soon as a dangerous situation occurs. In this paper, we propose a novel scheme employing a novel story?carry?forward (SCF) mechanism to tackle the network partition and broadcast storm problems, which are two major challenges in VANETs. The experimental result in the Veins simulation framework shows that the proposed SCF scheme significantly mitigates broadcast storms relative to other schemes, and maintains good coverage across various traffic densities.

In military applications, mobile ad hoc networks are commonly used due to the autonomy, self-configuration, and flexibility. In addition, spectrum sharing-based communication protocols are being actively considered due to spectrum shortage. We propose a cooperative phase-steering (CPS) technique for a spectrum sharing-based military mobile ad hoc network which consists of a single secondary source (SS) node, multiple secondary relay (SR) nodes, a single secondary destination (SD) node, and multiple primary destination (PD) nodes. In the proposed technique, the SR nodes that succeeded the packet decoding cooperatively adjust the phase of their transmit signals such that the received signals at the SD node from the SR nodes are aligned to a certain angle, while the SR nodes control the transmit power such that the received power at all PD nodes is lower than a certain threshold. Through extensive computer simulations, it is shown that the proposed technique outperforms the conventional cooperative relaying scheme in terms of outage probability.

In this paper, we propose a cooperative maximum-ratio transmission (C-MRT) technique with multi-antenna relay nodes for tactical mobile ad-hoc networks (MANETs) where both the location and the number of antennas of relay nodes are arbitrary. Each relay node is assumed to know both the wireless channel coefficient from the source node to itself and the wireless channel from itself to the destination node, which is known as local channel state information (CSI) assumption. Maximum-ratio combining (MRC) and MRT techniques are used for beamforming the transmit and receive signals of the relay node, respectively. In addition, we mathematically analyze the overall outage probability of the proposed technique with moment generating function (MGF). It is shown that the mathematical analysis on the overall outage probability of the proposed C-MRT technique is matched well with the simulation results especially in high transmit power regimes. It is also observed that the proposed technique outperforms other schemes such as phase steering (PS) and optimal relay selection (ORS) in terms of outage probability.

Recent developments in the fields of communications, smart transportation systems and computer systems have significantly expanded the potential for intelligent solutions in the domains of traffic safety, convenience and efficiency. The utilization of Artificial Intelligence (AI) is presently prevalent across diverse sectors of application due to its significant capacity to augment conventional data-driven methodologies. In the domain of Vehicular Ad hoc NETworks (VANETs), data is regularly gathered from several sources. The collected data serves multiple goals, such as facilitating efficient routing, enhancing driver awareness, forecasting mobility patterns to prevent potential risks, and ultimately enhancing passenger comfort, safety and overall road experience. Internet of thing (IoT) can be a good solution fro many issues that of VANETs. In order to make a complete system of VANETs communications are very essential like 5G and 6G. This study provides a detailed examination of AI, IoT and 5G/6G methodologies currently being investigated by multiple research endeavors in the field of VANETs. The merits and demerits of the AI-based methodologies suggested for the VANET domain have been analyzed with the using of IoT and 5G/6G. In conclusion, forthcoming research prospects in the field of VANETs are ascertained.

5G-based MANET has received a lot of attention recently. Its fundamental feature is that nodes are constantly subjected to high traffic loads, while QoS requirements are extremely stringent. When applied to 5G-based MANETs, existing routing protocols have shown drawbacks. In this paper, we propose an enhanced AODV protocol solution for 5G-based MANETs. Using reinforcement learning, each node updates a state information database of intermediate nodes along routes to destinations. This database is used by the routing algorithm to find guaranteed QoS routes. Our solution is highly efficient in terms of throughput, end-to-end delay, and SNR, according to the simulation results.

기존의 Greedy 경로 프로토콜은 일반적으로 차량 Ad-hoc 통신 (Vehicle Ad-hoc Networks) 에서 좋은 성능을 보인 다. 그러나 일시적으로 거리를 비게 만드는 교통신호가 존재하는 구간이나 분리된 도로가 합류하는 지점이 없는 도시의 도로에서 지형적인 영향으로 Greedy 라우팅 프로토콜은 잘못된 경로 라우팅 된 경우 불필요하게 경로가 길어지거나 라 우팅 실패가 많이 발생한다. 또한, 단순하게 목적지 노드와의 직선거리를 가지고 노드들의 우선순위를 부여하고 가장 낮 은 값을 가진 노드를 중계노드로 선택한다. 최근에 차랑 Ad-hoc 통신에서는 지리적인 환경의 특성 때문에 거리뿐만 아 니라 전달 방향도 중요한 요소 중에 하나이다. 그래서 본 논문은 개선된 프로토콜을 제안 하는데 하나의 노드가 패킷을 전달할 때 목적지 노드 까지를 지능적으로 거리 및 전달 방향성을 고려하여 다음 노드를 선정하고 교통 통신 상태를 지 능적 제어에 따라 보다 안정적인 경로 설정을 할 수 있게 하고 지형적 모델이 따라 자유롭게 변경이 가능 하게끔 관리 한다. 제안된 프로토콜 방법의 성능 분석은 두 가지의 이동모델을 적용한 네트워크 시뮬레이션을 통하여 검증하였고 대 부분의 경우 기존 프로토콜보다 좋은 성능을 보였다.

Greedy protocols show good performance in Vehicular Ad-hoc Networks (VANETs) environment in general. But they make longer routes causing by surroundings or turn out routing failures in some cases when there are many traffic signals which generate empty streets temporary, or there is no merge roads after a road divide into two roads. When a node selects the next node simply using the distance to the destination node, the longer route is made by traditional greedy protocols in some cases and sometimes the route ends up routing failure. Most of traditional greedy protocols just take into account the distance to the destination to select a next node. Each node needs to consider not only the distance to the destination node but also the direction to the destination while routing a packet because of geographical environment. The proposed routing scheme considers both of the distance and the direction for forwarding packets to make a stable route. And the protocol can configure as the surrounding environment. We evaluate the performance of the protocol using two mobility models and network simulations. Most of network performances are improved rather than in compared with traditional greedy protocols.

A clustering scheme for ad hoc networks is aimed at managing a number of mobile devices by utilizing hierarchical structure of the networks. In order to construct and maintain an effective hierarchical structure in ad hoc networks where mobile devices may move at high mobility, the following requirements must be satisfied. The role of each mobile device for the hierarchical structure is adaptive to dynamic change of the topology of the ad hoc networks. The role of each mobile device should thus change autonomously based on the local information. The overhead for management of the hierarchical structure is small. The number of mobile devices in each cluster should thus be almost equivalent. This paper proposes an adaptive multihop clustering scheme for highly mobile ad hoc networks. The results obtained by extensive simulation experiments show that the proposed scheme does not depend on mobility and node degree of mobile devices in the ad hoc network, which satisfy the above requirements.

Vehicular ad hoc network (VANET) has become most predominant on account of their usage in a vehicle to vehicle communication. But one of the major challenges in this network is the mobility of nodes involves in the communication. Either single-hop or multi-hop communication is used within the vehicle to vehicle communication. There are reactive, proactive, and hybrid routing protocols that are generally used within the multi-hop communication and for the path establishment, a reactive routing protocol named AODV is primarily used. Because of the decentralized nature of the network, there is a possibility of various attacks that reduce the performance of the network. One of the most devastating attacks is the Sybil attack which destroys the privacy of networks. This paper proposes a novel approach for the detection and isolation of the malicious nodes that are responsible for causing Sybil attack in VANETs through an improvement in the AODV protocol and thus the overall performance of the network is improved. Moreover, the proposed approach is compared with the existing one in terms of metrics like delay, packet loss, overhead, and throughput using the network simulator. Results confirmed that the proposed approach is quite effective in handling the network under the impact of a Sybil attack.

본 논문에서는 다중 홉 ad-hoc 네트워크가 단방향 경로를 포함하고 있는 경우 단방향 링크를 통하여 패킷을 전송하기 위한 효율적인 라우팅 프로토콜을 제안한다. 제안하는 프로토콜은 노드에서 패킷의 송신과 수신이 가능하도록 두개의 라우팅 테이블로 구성되어 있다. 프로토콜은 양방향 링크들로만 구성된 네트워크와 단방향 링크를 포함하는 네트워크 모두에 운용이 가능하다. 제안하는 프로토콜은 양방향 링크뿐만 아니라 단방향 링크도 고려한 방식이므로 패킷의 송신과 수신을 위한 경로 생성 시 단방향 링크에 대한 경로생성이 내재된다

We proposed a simple and efficient routing protocol designed specifically for multi-hop ad-hoc networks. The proposed protocol is composed of the two routing tables which work together to allow nodes to send and receive packets. All aspects of the protocol can be operated on networks entirely consisting bidirectional links and networks with unidirectional links. Finding unidirectional link is embedded in the routing protocol since we considered not only bidirectional links but also unidirec-tional links when we developed a method.

모바일 애드 혹 네트워크를 형성하는 노드들은 불규칙한 이동성을 갖기 때문에 소스 노드와 목적지 노드 간의 초기 경로 설정 시 임의의 시간동안 경로 유지가 가능한 최적의 중계 노드들을 선택하는 것이 중요하다. 이의 분석을 위해, 본 논문에서는 중계 노드들 간의 초기 거리 및 이동 속도를 고려한 링크 유지 확률을 유도하고 임의의 시간 동안 두 중 계노드 간 링크 유지가 가능한 최적의 거리를 제시하며, 이를 기반으로 임의의 두 노드 간에 설정되는 경로의 신뢰성을 분석한다.

Mobile nodes in MANETs have the nature of unrestricted mobility so that they will join and leave the network frequently. Therefore, it important consideration to determine the optimal distance progress between relaying nodes along the route in order to maintain the established route for an arbitrary length of time (i.e., route duration). In this paper, we derived the link maintenance probability by considering the initial distance between two relaying nodes and node mobility. Based on the link maintenance probability, we further analyzed the route stability by considering the impact of distance progress between relaying nodes along the route.

본 논문은 애드 혹 네트워크에서 다중 경로 설정을 위한 탐색 기법을 제안한다. 데이터 경로 설정은 요구기반 방식으로 동작하며, 소스와 목적지 노드 간의 다중 경로는 초기 경로 설정 과정에서 함께 구해진다. 이러한 다중 경로는 데이터 경로의 백업이나 부하 분산에 사용될 수 있다. 제안 방식에서는 소스와 목적지 노드 간 다중 경로를 찾기 위해, 사전 질의 방법을 사용한다. 이 방안은 중간 노드에서 응답 메시지를 처리할 때, 주변 노드와의 정보 교환을 통해 최적의 다음 노드를 선택하는 방안이다. 시뮬레이션 결과를 통해, 제안된 다중 경로 체계가 경로간의 만나는 횟수를 감소시켜 다중 경로의 더 좋은 분리도를 주고, 노드들이 이동하는 환경에서 더 높은 경로 생존 확률을 달성함을 알 수 있었다.

This paper suggests a multipath establishing scheme for ad hoc networks. Data paths are established by on-demand manner. Multipath are made as a sequence of route control message exchange at route setup process. Multipath can be used as a backup path or load balancing for data exchange. Proposed scheme uses a one-hop pre-search scheme for establishing multipath between source and destination. When a node selects a next node for route reply, the node finds optimal route by exchanging route information with neighbor nodes. Simulation results show that the proposed multipath scheme has better split characteristics among multipath and higher route survivability at the environment where nodes are moving.

무선 애드혹 네트워크에서 MAC layer의 효율을 높이기 위한 하나의 방법으로서 사용되는 MAC frame aggregation은 MAC layer에서 여러 개의 MPDU (MAC protocol data units)를 하나의 PPDU (PHY protocol data units)로 aggregation 시켜서 성능을 향상시키는 방법이다. 애드혹 네트워크에서 TCP 성능 향상을 위해서 사용되는 방법의 하나로서 CWL (congestion window limit)의 설정 방법이 있는데 이는 congestion window의 상한을 두어 부적절한 congestion window 크기가 선택에 따른 영향을 최소화 하고자 하는 방법이다. 본 논문에서는 MAC frame aggregation이 가능한 MANET에서 최적화된 TCP 성능을 위하여 CWL를 조정하는 방법에 대하여 다룬다.

MAC frame aggregation is a method that combines multiple MPDUs (MAC protocol data units) into one PPDU (PHY protocol data units) to enhance network performance at the MAC layer. In ad hoc networks, TCP underperforms due to the congestion window overshooting problem and thus by setting CWL (congestion window limit) TCP performance can be improved. In this paper, we investigate the problem of setting CWL for TCP performance optimization in ad hoc networks with MAC frame aggregation.

본 논문은 Vehicular Ad-Hoc Networks(VANETs) 환경에서 NFT와 블록체인 연동을 고려한 인센티브 메커니 즘 접근 방식을 제시하였으며, 고속 이동과 불안정한 네트워크 특성으로 인해 어려움을 겪는 차량 간 데이터 공유 문제를 해결하기 위해서 Non-Fungible Token (NFTs)와 스마트 계약 기술을 활용하였다. 연구의 핵심은 차량이 도로에서 수집하는 데이터는 가치 있는 자산으로 변환됨을 고려하였으며, 스마트 계약을 통해 수집된 데이터는 NFTs로 전환하고, 이를 기반으로 차량 운전자들에게 실질적인 보상이 제공하도록 하였다. 이때 주목할 만한 점은 이 시스템의 자동화된 프로세스로써, 데이터 공유부터 NFTs 생성, 보상 지급까지 모든 과정이 투명하고 안전하게 진행되며, 차량 운전자들은 자신이 제공한 데이터에 대해 공정한 보상이 보장되며, 따라서 향후 VANETs 네트워크 의 참여도와 효율성을 크게 높일 것을 기대한다. 본 논문은 기술적 제안 이외에 향후 교통 데이터 처리의 새로운 방 향성을 제시하며, 교통 데이터의 가치를 다시 정의하였으며 참여자들에게 실질적인 인센티브를 제공함으로써 협력 적이고 효율적인 VANETs 환경을 제시하였다.

This study presents an incentive mechanism that explores the integration of Non-Fungible Tokens (NFTs) and blockchain in the context of Vehicular Ad-Hoc Networks (VANETs). It utilizes NFTs and the smart contract technology to address the challenges for data sharing in vehicle, which are exacerbated by high-speed movement and unstable networks. The core premise in this study is that the data which is collected by vehicles; it is transformed in valuable assets. Data gathered through a smart contract is converted into NFTs which is enabling real compensation for vehicle users. A noteworthy aspect of this system is its automated process, ensuring that each step is transparent and secure. This guarantees fair compensation provided by vehicle drivers which is expected to enhance participation and efficiency within the VANETs in the future. In this paper, it proposes a new paradigm for the future traffic data, moving beyond a simple technical proposal. It advocates for a cooperative and efficient VANETs by redefining the value of data and offering tangible incentives to participants.

이동 Ad hoc 네트워크 (MANET: Mobile Ad-hoc Network)는 기존의 통신 인프라의 구축 여부와 무관하게 무선 단말기기간의 통신이 가능한 네트워크이다. Ad hoc 네트워크는 음영지역, 재난지역, 전쟁 시와 같은 통신 인프라가 구축되기 어려운 상황에서 유용하게 사용 될 수 있다. 그러나 음성 및 데이터 서비스 등과 같은 무선 서비스의 제공을 위해 많은 양의 네트워크 용량이 필요하게 되지만 기존의 제한된 주파수 자원에 따른 주파수 부족 상황 및 주파수 자원정책의 규제에 따라 원활한 주파수 사용이 어려운 상황이다. 이에 따라 높은 주파수 활용을 제공하는 무선 인지 시스템이 Ad hoc네트워크에 적용하여 보다 다양하고 확장된 네트워크 서비스를 제공할 수 있다. 본 논문에서는 기존의 단일 스펙트럼 센싱 및 협력 스펙트럼 센싱과 비교하여 Ad hoc 네트워크가 적용된 무선인지 시스템에서의 스펙트럼 센싱의 성능이 향상됨을 모의 실험 및 성능 분석을 통하여 나타내도록 한다.

Wireless devices can communicate between each other without existing infrastructure in mobile Ad-hod network. Ad hoc networks can be used under difficult conditions, where it is difficult to construct infrastructures, such as shadowing areas, disaster areas, war area, and so on. In order to support to considerable and various wireless services, more spectrum resources are needed. However, efficient utilization of the frequency resource is difficult because of spectrum scarcity and the conventional frequency regulation. Ad-hoc networks employing cognitive radio (CR) system that guarantee high spectrum utilization provide effective way to increase the network capacity. In this paper, we simulate and compare the performance of conventional single and cooperative spectrum sensing with CR system using ad-hoc networks. And we demonstrate performance improvement by analyzing the system performance.