A self-stabilizing algorithm for the maximum flow problem

Due to the dynamic change of the opportunistic network topology and the lack of stable information transmission paths between nodes, the traditional topology-based routing algorithm cannot achieve the desired routing performance. To address of this problem, this paper proposes a routing algorithm based on trajectory prediction (RATP). The routing protocol based on trajectory prediction can efficiently and quickly adapt to the network link quality instability and the dynamic changes of network topology. RATP algorithm constructs a node mobility model by analyzing the historical mobility characteristics of the nodes. According to the node prediction information, the metric value of the candidate node is calculated, and the node with the smaller metric value is selected as the data forwarding node, which can effectively reduce the packet loss rate and avoids excessive consumption. Simulation results show that compared with other algorithms, the proposed algorithm has higher data delivery ratio, and end-to-end data delay and routing overhead are significantly reduced.

Due to dynamic changes in network topology and constant changes in links between satellites, the routing paths calculated by the traditional shortest multipath routing algorithm are not updated in time, resulting in that the problematic paths are still transmitting data, so a large number of problems such as packet loss and service failure exist in the network. This paper designs a multipath routing algorithm for the satellite network topology which changes frequently, constrained multipath routing algorithm (CMRA). By calculating all feasible path of the entire network topology, CMRA will choose the multiple paths which satisfy the constraint conditions. After that, it will choose the lowest cost value of these paths. Repeatedly performing these operations, select multiple high-quality paths which satisfy the constraint conditions for traffic. Simulation results show that compared with the traditional shortest multipath routing algorithm and single path routing algorithm, the proposed routing algorithm is better in packet loss rate and average time delay.

In certain extreme environments where infrastructure such as base stations is absent, connections between nodes can be intermittent. Traditional networks struggle to function in these conditions. Delay Tolerant Network (DTN) are a network architecture designed for such scenarios. Utilizing Unmanned Aerial Vehicle (UAV) as nodes within DTN can enhance the network’s transmission capabilities and compensate for the deficiencies of ground nodes. However, previous routing methods have shortcomings. Given the high speed and greater freedom of movement of UAVs compared to ground nodes, the network topology is subject to constant and significant change. Traditional routing methods, which typically rely on predetermined rules for selecting forwarding nodes, struggle to adapt to such variations. This paper introduces Graph Neural Network (GNN) into routing decisions for DTN to learn network structural information and assist with routing decisions. In this paper, we first model the routing problem within DTN, accounting for the dynamic changes in network topology and limited resources. Subsequently, we propose a GNN-based dynamic routing method. This method utilizes a graph neural network model that takes as input the feature s of nodes at the current moment and the network’s connectivity information to generate optimal forwarding nodes for each data packet. The proposed method has been implemented in the Opportunistic Networking Environment (ONE) simulator. Experimental results indicate that our method achieves higher delivery ratio, lower latency, and reduced overhead compared to traditional methods.

Adaptive and low-cost resource synchronization based on data distribution service in high dynamic networks

Mobile ad hoc wireless network is a challenging system since all nodes operate on limited battery resource. Besides, the routing protocol has to be adapted to dynamic communication channels through multi-hop path selection due to mobile nodes and relays. Hence, it is necessary to make the multicast routing tree energy efficient and fault tolerance in a changing network topology. In the research, an approach is proposed to make reliable routing decisions with minimal energy consumption. In order to obtain the optimal solutions, a mathematical formulation and an optimization-based method with heuristics for routing strategy adjustment is proposed for jointly considering energy-efficient and dynamic changes in network topology. Simulation results show that the routing decision algorithm has more significant improvement than other traditional algorithms.

A-GR: A novel geographical routing protocol for AANETs

Due to many challenging issues in vehicular ad-hoc networks (VANETs), such as high mobility and network instability, this has led to insecurity and vulnerability to attacks. Due to dynamic network topology changes and frequent network re-configuration, security is a major target in VANET research domains. VANETs have gained significant attention in the current wireless network scenario, due to their exclusive characteristics which are different from other wireless networks such as rapid link failure and high vehicle mobility. In this are, the authors present a Secured and Safety Protocol for VANET (STVAN), as an intelligent Ad-Hoc On Demand Distance Vector (AODV)-based routing mechanism that prevents the Denial of Service attack (DoS) and improves the quality of service for secured communications in a VANET. In order to build a STVAN, the authors have considered a smart traffic environment in a smart city and introduced the concept of load balancing over VANET vehicles in a best effort manner. Simulation results reveal that the proposed STVAN accomplishes enhanced performance when compared with other similar protocols in terms of reduced delay, better packet delivery ratio, reasonable energy efficiency, increased network throughput and decreased data drop compared to other similar approach.

이동 애드-혹 네트워크는 물리적 위치 이동이 가능한 노트들에 의해 자체적으로 형성되는 시스템으로 동적 위상을 고려한 라우팅 프로토콜을 필요로 한다 본 논문에서는 IETT의 라우팅 프로토콜 DSR을 확장한 R-DSR이라 불리는 온-디멘드 다중경로 프로토콜을 제안한다. 제안된 프로토콜에서는 DSR에 의해 구축되는 단인 경로 상의 2-홉 간격의 모든 노드들에 대해 별도의 노드론 경유하는 추가 경로가 연결된다. 수학적 분석을 통하여 DSR 관련 연구 중 가장 대표적인 방법 중의 하나인 Das의 다중경로 프로토콜보다 더 높은 메시지 전달 확률을 제공함을 보였다. A mobile ad-hoc network is an autonomous system of mobile nodes which are free to move around randomly and organize themselves arbitrarily, hence a routing protocol that handles the dynamic network topology changes is required for the network. In this paper we present a multi -Path on-demand routing protocol called R-DSR (Robust Dynamic Source Routing), an extension to the existing IETF protocol DSR. The proposed protocol has it that every pair of 2-hop away nodes on the single route is additionally connected via an alternative node. Throughout mathematical analysis we show the proposed protocol reveals higher message delivery rate than that of the Das's multi-path protocol, currently known as one of the most typical approaches related to DSR.

Robust PMU Placement in Branch Switching Power Networks for Minimum Variance State Estimation

To solve the problem of the existing self-organizing network which mainly adopts unicast routing protocol and its narrow application, this paper proposes an improved load balancing-based non-coherent routing protocol - LIRP. This method can effectively avoid congestion node and path, make the network load equilibrium, and reduce the packet transmission end-to-end delay. It has a good adaptability with the dynamic change of network topology, which can shorten the routing reconstruction time caused by broken chains and improve the robustness of network and reliability of data transmission.

The paper proposed a wireless access authentication mechanism for unmanned systems, which can effectively solve the problem of secure access authentication under the dynamic change of network topology. The authentication process of cooperative authentication and the realization of secure access were designed to meet the application requirements of random access and anti-attack capabilities. The simulation results showed that the cooperative authentication mechanism not only ensures the security of the unmanned system, but also reduces the transmission overhead and the number of interactive authentications. The network access time is less than 30 milliseconds, and the success ratio of network access is close to 100%.

To solve the problem of low ratio success delivery, long latency caused by the rapid dynamic change of network topology, limited node buffer, large amount of data transmission and large user population density in delay-tolerant network (DTN). This paper propose a routing algorithm in DTN based on nodes’ sociality. In this paper, contact history was used to determine the node link quality; Markov model was used to predict the node position based on the nodes’ movement track; according to nodes’ social similarity to divide community, then calculated node betweenness centrality. Finally, the best forwarding nodes for message transmission were determined. Besides, to increase the ratio of successful delivery, message delivery probability in the relay node’s buffer was calculated. Experimental results show that compared with traditional routing algorithm, the proposed algorithm performs better on the delivery ratio and average end-to-end delay.

Group team communication serving for collaboration-work of special members, is an important application of MANET. In which, multicast protocol is a key technique to the group team application, which must guarantee the performance requirements: adaptable to the dynamic change of network topology, timeliness, minimizing routing overhead etc. This paper focuses on the improvement of MAODV applied to group team communication. Considering the existence of special nodes and determining the optimal repair node, GT-MAODV is proposed. After discussing the problems of link repair process of MAODV, a link repair mechanism--GTR-MAODV which improves the successful repair rate effectively through distinguishing different multicast tree branches is proposed on the basis of GT-MAODV. Through analysis and simulation, it is showed that the GTR-MAODV provides better performance than MAODV and GT-MAODV on successful repair rate, packet delivery rate and end to end delay.

Chapter 5 - Efficient CUDA Algorithms for the Maximum Network Flow Problem

We discuss a modular simulation framework to investigate the energy efficiency of different routing protocols used in resource constrained wireless sensor networks. Our simulation framework provides a flexible tool to build diverse protocols by combining existing building blocks at different layers and to analyse how several factors such as routing strategies, MAC protocols, link and node failures, energy on path, network topology changes, in-network processing, scheduling at MAC layer and other adjustable configuration parameters influence the energy efficiency of the protocol. The simulator extends the open source OMNeT++ and its Mo- bility Framework and provides a framework to rapidly develop, to experiment with and to evaluate efficiently routing protocols; the quantitative effort to design new routing protocols and to integrate them into a complete protocol stack is considerably reduced. Moreover, we develop complete modules for MAC and network protocols; in order to study and evaluate the behavior and lifetime of the network we implement independent energy and statistics modules. We provide also new features such as add/delete, move, dis/reconnect nodes during simulation, which allow to analyse the impact of dynamic topology changes. Index Terms—energy-aware, simulation, WSN protocols We first need energy-aware routing protocols which should take into account new metrics based on a sensor node's residual energy or other attributes to be able to take appropriate routing decisions in order to extend the lifetime of the WSN. Moreover, for a resource constrained sensor node it is very important that also the protocol stack operates efficiently and all the layers making up the protocol stack are optimized toward the specific requirements of the application running on top of it. In particular, the energy consumption must be optimized at each layer and the cooperation between layers should be improved. In order to achieve this, we proposed in (1) a modular, energy-aware network stack architecture of a sensor node as a flexible approach to design and plug-and- play various protocols at network and MAC layers, and to combine and analyse the impact of different strategies (inside the protocols) on performance and lifetime of the WSN. A. Motivation and objectives