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Ad Hoc Networks
Published in Jerry C. Whitaker, Microelectronics, 2018
Michel D. Yacoub, Paulo Cardieri, Élvio João Leonardo, Álvaro Augusto Machado Medeiros
An ad hoc network is a wireless network that is established without the aid of infrastructure or centralized administration. It is formed by a group of wireless terminals (nodes) such that a communication between any two terminals is carried out by means of a store-and-relay mechanism. A terminal wishing to transmit accesses the medium and sends its information to a nearby terminal. Upon receiving such information this terminal determines that this is not addressed to it. It then stores the information in order to relay it to another terminal at an appropriate time, and this process continues until the destination is reached. Note that in ad hoc networks there are no fixed routers. Nodes may be mobile and can be connected dynamically in an arbitrary manner. Nodes function as routers, which discover and maintain routes to other nodes in the network. Ad hoc networks find applications in emergency-and-rescue operations, meeting or conventions, data acquisition operations in inhospitable terrain, sensor networks, and home and office networks. Cheaper hardware, smaller transceivers, and faster processors fuel the increased interest in wireless ad hoc networks. This chapter addresses the ad hoc networks from four main aspects: routing, medium access, TCP/IP issues, and capacity. In routing, the main routing algorithms are illustrated. In medium access, the main medium access protocols are described. In TCP/IP issues, the aspects concerning the performance of TCP/IP in an ad hoc network is discussed. In capacity, some formulation concerning the capacity of the network is tackled.
Clustering Algorithms
Published in Jiguo Yu, Xiuzhen Cheng, Honglu Jiang, Dongxiao Yu, Hierarchical Topology Control for Wireless Networks, 2018
Jiguo Yu, Xiuzhen Cheng, Honglu Jiang, Dongxiao Yu
The ad hoc network, which was introduced in Chapter 1, is a new wireless network without infrastructure. It consists of dramatic nodes with wireless devices under the support of various protocols. Because of mobile nodes, the topology will change quickly in an unpredictable way along with the movement of nodes. The nodes can have the function of both host and router: As a host, a node can send and receive data; as a router, the node needs to switch the routing information, construct a routing table, and forward the corresponding data according to the routing protocol configured in advance. Compared with the wireless network based on the base station or the AP, the characteristics of the ad hoc network bring a lot of difficulties for scalability and management, such as noncenter structure and the mobility of nodes. Clustering is proposed as a popular solution to these difficulties and was first proposed in ad hoc networks. Mobile nodes with the same property (e.g., similar geographic position, similar motion behavior) use a clustering method. The cooperative work among the nodes in a cluster can improve the whole performance of the network. Generally, nodes in the same cluster are regarded as an autonomous domain. In a cluster, the node with the strongest ability will be chosen as a cluster head to manage the other nodes in the cluster. When it needs inter-cluster communication, the corresponding nodes will be responsible for communication and provide reliability for the ad hoc network. Figure 3.1 shows the clustering topology of the ad hoc network.
Wireless Infrared Networking
Published in Roberto Ramirez-Iniguez, Sevia M. Idrus, Ziran Sun, Optical Wireless Communications, 2008
Roberto Ramirez-Iniguez, Sevia M. Idrus, Ziran Sun
As for many other wireless networks, there are two basic optical wireless network architectures: (1) ad hoc and (2) infrastructure. The current IEEE 802.11 specification allows network interface cards to be set to work in either of these modes, but not in both simultaneously. An ad hoc network as illustrated in Figure 10.1 is the most basic form of a network, in which stations or mobile nodes cooperatively and spontaneously form the connections, independently of any fixed infrastructure or centralized administration such as a base station (BS) in a cellular wireless network or an access point (AP) in a wireless local area network. In general, these networks, which are characteristically limited both temporally and spatially, can be set up rapidly. In an ad hoc network, the nodes are dynamically and arbitrarily located, and the use of a multi-hop route to deliver data through other nodes in the network is possible.
A Modified DSR Protocol Using Deep Reinforced Learning for MANETS
Published in IETE Journal of Research, 2023
In recent years, Mobile Ad Hoc networks (MANETs) have been extensively studied as an alternative to infrastructure networks because of their ease of deployment. The targeted environments for ad hoc networks are typically inhospitable regions where it is difficult to set up infrastructure or environments where the existing infrastructure has collapsed temporarily or permanently. The growing development of information technologies has led to the emergence of various architectures among wired and wireless communication networks. Under wireless network technologies, Mobile Adhoc Network (MANET) is an encouraging research area because of its self-configuring wireless network of mobile devices or nodes, which communicate with each other using radio transmissions. Unlike traditional networks, an ad hoc network does not have a base station which acts as a router [1]. All intermediate nodes in a MANET act as a router and forwards packets on behalf of other nodes until the packet is received by the destination from its sender. MANETs rely on multi-hop transmissions among the nodes and in the past years, a lot of research has been encouraged due to considerable issues in routing techniques which include the large area of flooding, greedy forwarding, flat addressing and widely distributed information, large power consumption, interference and load balancing [2]. Hence an efficient routing protocol is required to enhance communication in MANET.
Quality of service assessment routing protocols for performance in a smart building: A case study
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
DSDV routing protocol is an extended version of the classical distributed Bellman-Ford algorithm (DBF). In the DSDV routing protocol, to prevent loop problems in the DBF algorithm, loops can be prevented by mixing the input of every routing table and an ordinal number for setting routing data. In this protocol, routing operations are performed between nodes by routing tables stored in every Ad-Hoc network node. In each node, routing tables determine all available D nodes and the number of levels to them (Perkins and Bhagwat 1994). The routing table input is connected to an ordinal number created by the D node. To keep track of routing table data correct, this protocol utilizes both activated and periodic routes updates. The activated route updates are done periodically so that it can broadcast routing data as quickly as possible when there is no topology change. Updated packages contain the destinations available at each node, the number of jumps needed for each D, and an ordinal number connected to that route. During the process, the data is stored in the time interval between the first receipt and the receipt of the best path for each particular D. The information structure might also be regulated to postpone the announcement of paths that are likely to vary, for eliminating fluctuations in route tables and reducing the number of repetitive broadcasts of routes entering with a sequential number (Sinwar et al. 2020).
An enhanced performance through agent-based secure approach for mobile ad hoc networks
Published in International Journal of Electronics, 2018
Dhananjay Bisen, Sanjeev Sharma
Ad hoc network is vulnerable due to its fundamental characteristics such as open medium, dynamic topology, distributed cooperation, congestion, energy constraints, variable capacity links and security. Nodes work together as a team for forwarding packets between sources to destination. But due to security vulnerabilities and dynamic nature of network, mobile ad hoc networks may be unprotected against selfish and malicious behaviour of nodes. Such nodes show their presence between source and destination at the time of route discovery in which they always update their routing table but at the time of data forwarding they might not forward the data packets and intentionally drop it. The reason because of which a node may be considered as malicious is given below: Nodes drop forwarding packets due to its selfishness nature.Packets can be dropped by any set of congestion, collision and delay occurring in nodes.