Copies Of Message Research Articles

Comparing Statistical, Analytical, and Learning-Based Routing Approaches for Delay-Tolerant Networks

In delay-tolerant networks (DTNs) with uncertain contact plans, the communication episodes and their reliabilities are known a priori. To maximise the end-to-end delivery probability, a bounded network-wide number of message copies are allowed. The resulting multi-copy routing optimization problem is naturally modelled as a Markov decision process with distributed information. In this paper, we provide an in-depth comparison of three solution approaches: statistical model checking with scheduler sampling, the analytical RUCoP algorithm based on probabilistic model checking, and an implementation of concurrent Q-learning. We use an extensive benchmark set comprising random networks, scalable binomial topologies, and realistic ring-road low Earth orbit satellite networks. We evaluate the obtained message delivery probabilities as well as the computational effort. Our results show that all three approaches are suitable tools for obtaining reliable routes in DTN, and expose a trade-off between scalability and solution quality.

About an Unknown Letter “from the Newly Conquered City of Areshek”

A handwritten book Collection of Military Letters is kept in the funds of the Russian National Library. It is a collection containing copies of messages about the military operations of parts of the Russian Army in 1702–1710. The study of the manuscript makes it possible to establish that the collection comes from the office of Boyar T. N. Streshnev and belonged to Clerk I. P. Topilsky. On the first pages of the collection, there is a previously unknown letter with a message about the assault and capture of the fortress of Nöteborg. An analysis of the letter demonstrates that its author was P. P. Shafirov, secretary of the Ambassadorial Prikaz. He was sent to Nöteborg to negotiate the conditions for surrendering the fortress. The letter contains information about the events of the assault, the course of negotiations, an assessment of the damage to the fortifications, and reports on the losses of the Russian side. Shafirov’s letter, written the day after the assault, is much longer than the known letters of Peter I but is not a work of the editors who created the official text of the report much later. The introduction of a new source about the assault and capture of Nöteborg adds to the knowledge about one of the significant events of the initial stage of the Northern War.

SCAP SigFox: A Scalable Communication Protocol for Low-Power Wide-Area IoT Networks

The Internet of Things (IoT) is a new future technology that is aimed at connecting billions of physical-world objects to the IT infrastructure via a wireless medium. Many radio access technologies exist, but few address the requirements of IoT applications such as low cost, low energy consumption, and long range. Low-Power wide-area network (LPWAN) technologies, especially SigFox, have a low data rate that makes them suitable for IoT applications, especially since the lower the data rate, the longer the usable distance for the radio link. SigFox technology achieves as a main objective network reliability by striving for the successful delivery of data messages through redundancy. Doing so results in one of the SigFox weaknesses, namely the high collision rate, which questions SigFox scalability. In this work, we aimed at avoiding collisions by changing SigFox's Aloha-based medium access protocol to TDMA and by using only orthogonal channels while removing redundancy. Consequently, every node sends a single copy of the data message on a given orthogonal channel in a specific time slot. To achieve this, we implemented a slot- and channel-allocation protocol (SCAP) on top of SigFox. In other words, our goal was to improve SigFox's scalability by implementing two mechanisms: time slot allocation and channel allocation. Performance analysis was conducted on large networks with sizes ranging from 1000 to 10,000 nodes to evaluate both technologies: the original SigFox and SCAP SigFox. The simulation results showed that SCAP SigFox highly reduced the probability of collision and energy consumption when compared to the original SigFox. Additionally, SCAP SigFox had a greater throughput and packet delivery ratio (PDR).

Enhanced Message Replication Technique for DTN Routing Protocols

Delay-tolerant networks (DTNs) are networks where there is no immediate connection between the source and the destination. Instead, nodes in these networks use a store-carry-forward method to route traffic. However, approaches that rely on flooding the network with unlimited copies of messages may not be effective if network resources are limited. On the other hand, quota-based approaches are more resource-efficient but can have low delivery rates and high delivery delays. This paper introduces the Enhanced Message Replication Technique (EMRT), which dynamically adjusts the number of message replicas based on a node's ability to quickly disseminate the message. This decision is based on factors such as current connections, encounter history, buffer size history, time-to-live values, and energy. The EMRT is applied to three different quota-based protocols: Spray and Wait, Encounter-Based Routing (EBR), and the Destination-Based Routing Protocol (DBRP). The simulation results show that applying the EMRT to these protocols improves the delivery ratio, overhead ratio, and latency average. For example, when combined with Spray and Wait, EBR, and DBRP, the delivery probability is improved by 13%, 8%, and 10%, respectively, while the latency average is reduced by 51%, 14%, and 13%, respectively.

A DTN oriented adaptive routing algorithm based on node load

In recent years, Delay Tolerant Networks (DTN) have received more and more attention. At the same time, several existing DTN routing algorithms generally have disadvantages such as poor scalability and inability to perceive changes in the network environment. This paper proposes an AdaptiveSpray routing algorithm. The algorithm can dynamically control the initial maximum message copy number according to the cache occupancy rate of the node itself, and the cache occupancy rate is added as an impact factor to the calculation of the probability of each node meeting the destination node. In the forwarding phase, the node will first compare the meeting probability of itself and the meeting node to the destination node, and then choose different forwarding strategies. The simulation shows that the AdaptiveSpray algorithm proposed in this paper has obvious advantages compared with the existing routing algorithms in terms of message delivery rate and average delay.

Effective Data Optimization and Evaluation Based on Social Communication with AI-Assisted in Opportunistic Social Networks

Billions of people around the world send and receive data over online networks daily. Sufficient and redundant data are transmitted over social platforms with AI-assisted in 5G networks. In opportunistic social networks, the main challenge faced by traditional methods is that numerous user nodes participate in data transmission, causing a lot of message copy redundancy and node cache consumption. As a result, the transmission delay of the algorithm is high, the node energy consumption is too large, and even information is lost. To solve these problems, this study establishes an artificial intelligence-based optimization multiple evaluation method. The main purpose of this method is to avoid information loss caused by data loss when reducing data noise, reasonably select communication nodes in opportunistic social network scenarios, optimize data transmission performance, and avoid network congestion. Moreover, our method can effectively identify and exclude potential malicious nodes, reducing the situation that packets are intercepted and discarded. The experiment confirms that the optimized transmission evaluation scheme can effectively reduce routing overheads and energy consumption of a user node, improve the delivery ratio of node data transmission, and ensure the reliability and security of data transmission.

A Probabilistic Spray-and-Wait Routing Algorithm Based on Node Interest Preference in Delay Tolerant Networks

How to select proper relay nodes to ensure the successful delivery of messages is still a hot topic in delay tolerant networks (DTN). In this paper, we propose a probabilistic Spray-and-Wait routing algorithm based on node interest preference (called NIP-PSW). Firstly, considering the influence of the social attributes of nodes, we define a metric called node interest preference (NIP) to measure the probability of nodes becoming friends. Secondly, in view of the influence of node quality and connection time between nodes on message forwarding, we define the delivery probability (DP). Finally, according to the historical information of nodes, the node interest similarity (NIS) is proposed. In spray phase, NIP and DP are used to select the relay node and allocate the number of message copies adaptively. In wait phase, it is judged whether to forward the message to the encountering nodes again according to the NIS and the DP. In addition, the concept of message storage value (MSV) and the acknowledgment (ACK) mechanism are introduced to manage the buffer of nodes. The simulation results show that the NIP-PSW not only can significantly improve the delivery rate and reduce the average delay but also shows good performance in network overhead and average number of hops.

Efficient Reservation-based Fault-Tolerant Scheduling for IEEE 802.1Qbv Time-Sensitive Networking

Time-Sensitive Networking (TSN) is one of the enhanced Ethernet technologies for the real-time application of industrial networks in the future. However, unexpected data errors caused by transient influence like electromagnetic interference may be occurred during the data transmission. One common way to tolerate such failures is to directly transmit multiple instance copies, such as IEEE 802.1 CB. However, wasting limited network resources is one of the drawbacks, since not all message copies could be received incorrectly. Cyclic Redundancy Check (CRC) can detect such errors when data is received, then the detection result is notified to the sending node. Despite that the re-transmission is performed only if the returned detection result is negative or time-out, the occurrence of errors are uncertain. Consequently, the time when responding to the re-transmission requests is also random, which results in different transmission sequences and violates the deterministic transmission service of TSN. Furthermore, CRC detection results messages also might be fault during transmission. To tackle the above drawbacks, we propose a novel offline reservation-based fault-tolerance scheduling algorithm for IEEE 802.1 Qbv TSN. Firstly, the Dijkstra algorithm is used to generate the routing for each flow. Then, the resource allocation is generated by Satisfiability Modulo Theories according to TSN constraints formulated to guarantee the deterministic transmission for Time-Trigger (TT) flows, CRC-related flows, and the reserved re-transmissions of TT flows. Finally, the queues are also open for non-TT flows in the time slice reserved for re-transmissions of TT flows to enhance the throughput of non-TT flows. Through extensive simulations, we demonstrate the effectiveness of the proposed approach in terms of acceptance ratio, execution time and the wasted resources.

A Wireless Mesh Opportunistic Network Routing Algorithm Based on Trust Relationships

To solve the problem of low message delivery rate and high network resource consumption when forwarding messages in opportunistic networks, an opportunistic routing algorithm based on trust relationships for wireless mesh networks is proposed. Firstly, the wireless mesh network is analyzed and the opportunistic routing model is constructed; By analyzing the security mechanism and security threat of communication entities, then measuring the trust degree of links and nodes, establishing the trust relationship between nodes, and defining and quantifying a new security measurement method based on the trust model; Finally, according to the security measurement method defined by the model, select the node with high trust value to participate in the message forwarding process. At the same time, give priority to the node with greater trust with the destination node as the relay node, and allocate the message copy according to the trust degree to make the message pass along the direction of increasing trust, to complete the design of opportunistic routing algorithm in wireless mesh networks. Experimental results show that the routing algorithm can effectively improve the message delivery rate, up to about 95%, and reduce the consumption of network resources.

An Adaptive Routing Algorithm Based on Relation Tree in DTN.

It is found that nodes in Delay Tolerant Networks (DTN) exhibit stable social attributes similar to those of people. In this paper, an adaptive routing algorithm based on Relation Tree (AR-RT) for DTN is proposed. Each node constructs its own Relation Tree based on the historical encounter frequency, and will adopt different forwarding strategies based on the Relation Tree in the forwarding phase, so as to achieve more targeted forwarding. To further improve the scalability of the algorithm, the source node dynamically controls the initial maximum number of message copies according to its own cache occupancy, which enables the node to make negative feedback to network environment changes. Simulation results show that the AR-RT algorithm proposed in this paper has significant advantages over existing routing algorithms in terms of average delay, average hop count, and message delivery rate.

Microsoft's Your Phone environment from a digital forensic perspective

Your Phone is a Microsoft dual mobile/desktop application that links a Windows 10 environment to a smartphone. The Android version provides the smartphone's user with the ability to control the mobile device from Windows 10, allowing to place/receive calls, send/receive text messages such as SMS, MMS and RCS, access up to the last 2000 photos/screenshots of the device and to receive notifications from applications, all through the Windows 10 Your Phone application and, if configured to do so, within Windows 10 notification center.This work analyzes the Your Phone environment, that is, Your Phone Companion for Android and Your Phone for Windows 10. The paper studies the digital forensic artifacts that can be found in a post mortem analysis, focusing on the SQLite3 databases used by both the Android and Windows 10 applications. We also compare the examined version with a previous version of Your Phone, showing that Your Phone newest functionalities bring new valuable artifacts for forensic examiners.The study shows that Your Phone data left on a Windows 10 device can be useful to access a copy of messages, photos, and document interactions, especially when the Android device is inaccessible or even physically unavailable. To ease the task for digital forensic examiners, we have updated our open-source YPA software that collects and analyzes Your Phone data from a Windows 10 system. YPA runs as a module within the digital forensic Autopsy software.

Routing Algorithm Based on User Adaptive Data Transmission Scheme in Opportunistic Social Networks

With the rapid popularization of 5G communication and internet of things technologies, the amount of information has increased significantly in opportunistic social networks, and the types of messages have become more and more complex. More and more mobile devices join the network as nodes, making the network scale increase sharply, and the tremendous amount of datatransmission brings a more significant burden to the network. Traditional opportunistic social network routing algorithms lack effective message copy management and relay node selection methods, which will cause problems such as high network delay and insufficient cache space. Thus, we propose an opportunistic social network routing algorithm based on user-adaptive data transmission. The algorithm will combine the similarity factor, communication factor, and transmission factor of the nodes in the opportunistic social network and use information entropy theory to adaptively assign the weights of decision feature attributes in response to network changes. Also, edge nodes are effectively used, and the nodes are divided into multiple communities to reconstruct the community structure. The simulation results show that the algorithm demonstrates good performance in improving the information transmission’s success rate, reducing network delay, and caching overhead.

Opportunistic Network Algorithms for Internet Traffic Offloading in Music Festival Scenarios.

Constant Internet connectivity has become a necessity in our lives. Hence, music festival organizers allocate part of their budget for temporary Wi-Fi equipment in order to sustain the high network traffic generated in such a small geographical area, but this naturally leads to high costs that need to be decreased. Thus, in this paper, we propose a solution that can help offload some of that traffic to an opportunistic network created with the attendees’ smartphones, therefore minimizing the costs of the temporary network infrastructure. Using a music festival-based mobility model that we propose and analyze, we introduce two routing algorithms which can enable end-to-end message delivery between participants. The key factors for high performance are social metrics and limiting the number of message copies at any given time. We show that the proposed solutions are able to offer high delivery rates and low delivery delays for various scenarios at a music festival.

Genetic Improvement of Routing Protocols for Delay Tolerant Networks

Routing plays a fundamental role in network applications, but it is especially challenging in Delay Tolerant Networks (DTNs). These are a kind of mobile ad hoc networks made of, e.g., (possibly, unmanned) vehicles and humans where, despite a lack of continuous connectivity, data must be transmitted while the network conditions change due to the nodes’ mobility. In these contexts, routing is NP-hard and is usually solved by heuristic “store and forward” replication-based approaches, where multiple copies of the same message are moved and stored across nodes in the hope that at least one will reach its destination. Still, the existing routing protocols produce relatively low delivery probabilities. Here, we genetically improve two routing protocols widely adopted in DTNs, namely, Epidemic and PRoPHET, in the attempt to optimize their delivery probability. First, we dissect them into their fundamental components, i.e., functionalities such as checking if a node can transfer data, or sending messages to all connections. Then, we apply Genetic Improvement (GI) to manipulate these components as terminal nodes of evolving trees. We apply this methodology, in silico, to six test cases of urban networks made of hundreds of nodes and find that GI produces consistent gains in delivery probability in four cases. We then verify if this improvement entails a worsening of other relevant network metrics, such as latency and buffer time. Finally, we compare the logics of the best evolved protocols with those of the baseline protocols, and we discuss the generalizability of the results across test cases.

An adaptive multiple spray-and-wait routing algorithm based on social circles in delay tolerant networks

In delay tolerant networks (DTN), the social attributes of nodes show long-term stability, which can be leveraged for more effective routing. In this paper, we first present a novel way of constructing social circles based on the node clustering phenomena in DTN. Then, considering that the forwarding capability of nodes is significantly different, we propose a spray strategy based on social circles (named SC-SS) to improve the spray-and-wait routing algorithm. SC-SS selects the next hop based on the social circle of nodes in the spray phase. Instead of fixing the initial number of copies, we design an adaptive multiple spray-and-wait routing algorithm based on social circles (named SC-AMSW) to further improve the performance of SC-SS. SC-AMSW selectively sprays messages multiple times in the wait phase and determines an appropriate number of redundant message copies based on delivery predictability. We conduct extensive simulations to confirm the effectiveness of our proposed routing algorithms in DTN.

Impact of contacts for message copies, mobile nodes and buffer size in delay-tolerant networks

Delay tolerant network is a mobile ad hoc network where there are no predefined routes from one node to another, which is used in disaster and emergency communications. Here, we concentrate the analysis of node contact on contact duration aware routings techniques and address the issues of variation of mobile nodes, message copies and buffer size using ONE simulator. We observe that contact increases per hour with the increase of mobile nodes, while goes up and down for varying message copies and remains approximately the same for buffer size, i.e., buffer size does not affect the achievement of contacts. While, inter-contact time (ICT) is high at the beginning of communication for three cases, i.e. for varying message copies, mobile nodes and buffer size. Higher contact time results in higher ICT and number of contacts for varying mobile nodes, while it remains slightly changed for varying message copies and fixed for varying buffer size.

Impact of contacts for message copies, mobile nodes and buffer size in delay-tolerant networks

Delay tolerant network is a mobile ad hoc network where there are no predefined routes from one node to another, which is used in disaster and emergency communications. Here, we concentrate the analysis of node contact on contact duration aware routings techniques and address the issues of variation of mobile nodes, message copies and buffer size using ONE simulator. We observe that contact increases per hour with the increase of mobile nodes, while goes up and down for varying message copies and remains approximately the same for buffer size, i.e., buffer size does not affect the achievement of contacts. While, inter-contact time (ICT) is high at the beginning of communication for three cases, i.e. for varying message copies, mobile nodes and buffer size. Higher contact time results in higher ICT and number of contacts for varying mobile nodes, while it remains slightly changed for varying message copies and fixed for varying buffer size.

Performance Analysis of DEBT Routing Protocols for Pocket Switch Networks

Pocket Switched Networks (PSN) represent a particular remittent network for direct communication between the handheld mobile devices. Compared to traditional networks, there is no stable topology structure for PSN where the nodes observe the mobility model of human society. It is a kind of Delay Tolerant Networks (DTNs) that gives a description to circulate information among the network nodes by the way of taking the benefit of transferring nodes from one area to another. Considering its inception, there are several schemes for message routing in the infrastructure-less environment in which human mobility is only the best manner to exchange information. For routing messages, PSN uses different techniques such as Distributed Expectation-Based Spatio-Temporal (DEBT) Epidemic (DEBTE), DEBT Cluster (DEBTC), and DEBT Tree (DEBTT). Understanding on how the network environment is affected for these routing strategies are the main motivation of this research. In this paper, we have investigated the impact of network nodes, the message copies per transmission, and the overall carrying out of these routing protocols. ONE simulator was used to analyze those techniques on the basis of delivery, overhead, and latency. The result of this task demonstrates that for a particular simulation setting, DEBTE is the best PSN routing technique among all, against DEBTC and DEBTT.

Avoiding Spurious Retransmission over Flooding-Based Routing Protocol for Underwater Sensor Networks

In underwater wireless sensor networks (UWSN), acoustic communication naturally introduces challenges such as long propagation delay and high packet loss. The flooding-based routing protocol can address these challenges with its multipath characteristics. As in flooding-based routing, due to multipath propagation mechanism, not only DATA but also ACK messages are transmitted through multiple routes however still some packet loss will degrade the performance. So, to provide high reliability of message delivery, an efficient retransmission mechanism is inevitable. Though, if the network uses conventional transport layer protocol such as TCP, it will suffer a spurious retransmission problem as TCP was originally not designed for the multipath environment. In this paper, we propose route discrimination for flooding-based routing to reduce spurious retransmission in UWSN to solve the limitation. The notion of ACK copies waiting time (ACWT) is utilized which is selectively updated based on the similarity of paths of transmission of ACK message copies. We also improved our previous solution that lacks flexibility to cope with dynamic link error characteristics. Through evaluation, we verified that our new scheme achieves the performance improvements of 14%~84% in terms of retransmission ratio compared to the previous research.

Quantum Proxy Signature Scheme with Discrete Time Quantum Walks and Quantum One-Time Pad CNOT Operation

The quantum proxy signature is one of the most significant formalisms in quantum signatures. We put forward a quantum proxy signature scheme using quantum walk-based teleportation and quantum one-time pad CNOT (QOTP-CNOT) operation, which includes four phases, i.e., initializing phase, authorizing phase, signing phase and verifying phase. The QOTP-CNOT is achieved by attaching the CNOT operation upon the QOTP and it is applied to produce the proxy signature state. The quantum walk-based teleportation is employed to transfer the encrypted message copy derived from the binary random sequence from the proxy signer to the verifier, in which the required entangled states do not need to be prepared ahead and they can be automatically generated during quantum walks. Security analysis demonstrates that the presented proxy signature scheme has impossibility of denial from the proxy and original signers, impossibility of forgery from the original signatory and the verifier, and impossibility of repudiation from the verifier. Notably, the discussion shows the complexity of the presented algorithm and that the scheme can be applied in many real scenarios, such as electronic payment and electronic commerce.