The Internet of Underwater Things (IoUT) requires a fast and trustworthy communication framework in order to ensure the timely delivery of mission-critical data in dynamic environments. Named Data Networking (NDN), a data-centric architecture, offers inherent data authentication and in-network caching. However, secure data exchange across organizational or administrative domains becomes a challenge due to isolated trust schemas. This paper proposes and evaluates an Inter-Zone Trust framework within NDN that allows for controlled and authenticated communication between multiple trust zones in an IoUT environment. A custom simulation is implemented using ndnSIM, custom producer, consumer, and controller apps, and dynamic trust revocation. Three simulation scenarios, namely, baseline, inter-zone trust, and malicious attack of a trust revocation is used to quantify potential performance overhead. The results of application delay, packet count, and energy consumption show that despite the slight increase in overhead, the proposed inter-zone trust architecture successfully responds to cache poisoning attacks and provides a scalable foundation for secure inter-zone communication for multi-organizational IoUT deployments.

Spatial transcriptomics is an emerging technology that allows for analysis of cellular and molecular heterogeneity at spatial resolution. The accurate identification of pathological regions in spatial transcriptomics data is essential for understanding tissue heterogeneity and disease progression. We introduce UPSST, a comprehensive framework that integrates tissue morphology, imputes gene expression, and clusters spatial regions using a graph attention neural network (GAT). UPSST was evaluated across multiple spatial transcriptomics datasets, achieving high performance, such as achieving an Adjusted Rand Index (ARI) of 0.737 and a Fowlkes-Mallows Index (FMI) of 0.818 on slice 151671 of the LIBD human dorsolateral prefrontal cortex (DLPFC) dataset. These results highlight the robustness and precision of our approach in identifying pathology domains. Additionally, UPSST facilitates downstream analyses such as differential and enrichment analysis, which are crucial for deriving biological insights. In conclusion, UPSST offers a powerful and reliable tool for spatial transcriptomics analysis, advancing the identification of pathological regions with high accuracy.

Autonomous Underwater Vehicles (AUVs) play a crucial role in applications such as deep-sea exploration and military operations. However, variations in temperature, salinity, and depth affect the speed of sound, leading to communication delays and signal degradation. These environmental factors in-troduce uncertainties that complicate effective communication and may increase energy consumption as AUV s sometimes need to expend additional power to maintain connectivity due to the position drift.

Distributed Particle Swarm Optimization (DPSO) is a powerful algorithm that can instruct a group of AUVs to conduct search operation. However, the effectiveness of DPSO is constrained by local communication. In this paper, we proposed an Ad-hoc communication strategy that can greatly extend the effectively communication range of DPSO. By utilizing the Ad-hoc communication strategy, nbest can be shared with other AUVs several hops away. The preliminary result shows the effectiveness of our proposed scheme.

In the field of drug discovery, a proliferation of pre-trained models has surfaced, exhibiting exceptional performance across a variety of tasks. However, the extensive size of these models, coupled with the limited interpretative capabilities of current fine-tuning methods, impedes the integration of pre-trained models into the drug discovery process. This paper pushes the boundaries of pre-trained models in drug discovery by designing a novel fine-tuning paradigm known as the Head Feature Parallel Adapter (HFPA), which is highly interpretable, high-performing, and has fewer parameters than other widely used methods. Specifically, this approach enables the model to consider diverse information across representation subspaces concurrently by strategically using Adapters, which can operate directly within the model's feature space. Our tactic freezes the backbone model and forces various small-size Adapters' corresponding subspaces to focus on exploring different atomic and chemical bond knowledge, thus maintaining a small number of trainable parameters and enhancing the interpretability of the model. Moreover, we furnish a comprehensive interpretability analysis, imparting valuable insights into the chemical area. HFPA outperforms over seven physiology and toxicity tasks and achieves state-of-the-art results in three physical chemistry tasks. We also test ten additional molecular datasets, demonstrating the robustness and broad applicability of HFPA.

Whole Slide Images (WSIs) are paramount in the medical field, with extensive applications in disease diagnosis and treatment. Recently, many deep-learning methods have been used to classify WSIs. However, these methods are inadequate for accurately analyzing WSIs as they treat regions in WSIs as isolated entities and ignore contextual information. To address this challenge, we propose a novel Dual-Granularity Cooperative Diffusion Model (DCDiff) for the precise classification of WSIs. Specifically, we first design a cooperative forward and reverse diffusion strategy, utilizing fine-granularity and coarse-granularity to regulate each diffusion step and gradually improve context awareness. To exchange information between granularities, we propose a coupled U-Net for dual-granularity denoising, which efficiently integrates dual-granularity consistency information using the designed Fine- and Coarse-granularity Cooperative Aware (FCCA) model. Ultimately, the cooperative diffusion features extracted by DCDiff can achieve cross-sample perception from the reconstructed distribution of training samples. Experiments on three public WSI datasets show that the proposed method can achieve superior performance over state-of-the-art methods. The code is available at https://github.com/hemo0826/DCDiff.

The paper introduces a deep reinforcement learning model for a special scenario in future smart transportation. The scenario describes a mobile edge computing platform hosted by a group of self-organized connected vehicles for sharing computation resources. The presented DQN model is to solve the trade-offs between the computing capability and the traffic state. Results show the existence of the trade-off and the need for future research in a few areas.

When network is undergoing problems, such as DDoS attack, component failures, etc., the detection of heavy flows (e.g. heavy hitters and heavy changers) is much more critical. However, it has been increasing challenging to ensure the accurate detection of heavy flows while dealing with massive network traffic volume, diversified traffic distribution and the stringent memory requirement. Although recent research efforts like LD-Sketch are scalable for diverse network traffic, they depend on excessive memory to maintain high accuracy, such that they fail to work well when the memory is limited. We propose RL-Sketch, a adaptive sketch using reinforcement learning in detecting heavy flows. It predicts potential heavy flows based on the statistics of network traffic, to achieve both high accuracy and scalability with minor memory. Trace-driven evaluation shows that RL-Sketch achieves higher accuracy than state-of-the-art sketch-based technologies with up to 17.79× accuracy gain, while maintaining high robustness in extreme conditions.

A college transit system is both important, and different from a general transit system. In this paper, we present a model to predict the arrival time of a college transit vehicle every second to provide information at each stop. The prediction model is divided into two separate modules that make the prediction of the moving time and the stopping time, respectively. The results of the two modules are then combined to obtain the final arrival time prediction. The method can be employed along with the V2I communication to inform the current location of the vehicle to predict the arrival time and can be easily extended to obtain the transit priority at the intersections. The presented model has better results in comparison to the existing work and is expected to be equally useful for any general transit system.

Vehicle-crowd (V-crowd) based cloudlets are envisioned to support high-demand mobile edge computing applications. Yet, a v-crowd's capability to host cloudlet applications is significantly affected by the sustainability of itself. Among the factors that may contribute to the capability and sustaining the v-crowd, traffic signal coordination plays an important role. In this paper, we study the interdependence between them through an empirical approach. We'll define new metrics to quantify the impact, and use data driven simulation to obtain results by manipulating signals offset as a control knob of traffic signal coordination. The goal is to use the results in terms of the metrics to develop guidelines that offer choices of offsets preferable for certain levels of v-crowd properties so as to achieve better performance of cloudlet applications.

As datacenter networks become increasingly programmable with proliferating network functions, network programming languages have emerged to simplify the program development of the network functions. While network functions exhibit high level abstraction over operations on the traffic flow and the interconnections among the operations, the existing languages usually require programming with detailed knowledge about the packet processing patterns at the switches. Such a mismatch between the program abstraction and development details makes developing network functions a nontrivial task. To solve the problem, this paper introduces the easy path programming (EP2) framework. EP2 offers a high-level abstraction to simplify the program design process of the network functions. EP2 also provides a language that captures the common properties of network functions and uses predicates and primitives as basic language components. Specifically, predicates describe when to handle a flow with a global view of the flow dynamics; and primitives describe how to choose a path for a specific flow. Furthermore, EP2 has its own runtime system to support the language and the abstraction model, especially to hide the low level packet-processing behavior at the data plane from the programmers. Throughout this paper, cases are given to illustrate the EP2 abstraction model, language details and benefits. The expressiveness of EP2, the potential overhead of the runtime system and the efficiency of the network functions generated by EP2 are evaluated. The results show that EP2 can achieve comparable performance while reducing programming efforts.

This paper is driven by a simple question of whether traffic engineering in Software Defined Networking (SDN) can react quickly to bursty and unpredictable changes in traffic demand. The key challenge is to strike a careful balance between the overhead (frequently involving the SDN controller) and performance (the degree of congestion measured as the maximum load and the balance between the minimum and the maximum loads). Exploiting OpenFlow (OF) features, quick shift of routing paths for unpredictable traffic bursty is the focal point of this work. It is achieved by using a dual routing scheme and letting the data plane to select the appropriate path in reacting to uncertainty in traffic load. The proposed work is called DUCE (Demand Uncertainty Configuration sElection). Further, we describe a traffic distribution model, an optimization solution that calculates congestion-free traffic distribution plan which guarantees that each switch can select one of the paths in a distributed way, and moreover, OF details about detaching the functionality of responding to the demand uncertainty from the control plane and delegating it to the data plane. Simulations are performed validating the efficiency of DUCE under various network scenarios.

Named Data Networking (NDN) has been considered as a promising networking architecture for Vehicular Ad-Hoc Networks (VANETs). However, Interest forwarding in NDN suffers severe issues in vehicular environment. Broadcast storm results in much packet loss and huge transmission overhead. Also, link disconnection caused by highly dynamic topology leads to low packet delivery ratio. On the other hand, traffic data are playing significant roles in VANETs since they are essential in varieties of Intelligent Transportation System (ITS) applications. Thus, an efficient NDN forwarding strategy using geographical characteristics to retrieve traffic data is urgently required. In this paper, we propose Density-Aware Delay-Tolerant (DADT) Interest forwarding strategy to retrieve traffic data in vehicular NDN with the purpose of improving packet delivery ratio. DADT specifically addresses data retrieval during network disruptions using Delay Tolerant Networking (DTN). It makes retransmission decision based on directional network density. Also, DADT mitigates broadcast storm by using rebroadcast deferring timer. We compared DADT against other strategies through simulation and the results show that it can achieve higher satisfaction ratio while keeping low transmission overhead.

Vehicular networks are expected to support numerous applications, such as emergency announcement, traffic congestions for travelers and intelligent transportation systems. But due to high vehicular mobility, vehicular networks suffer long transmission delay and intermittent end-to- end connectivity. The paper proposes a reliable forwarding strategy aiming to establish reliable end-to-end connection taking vehicular velocity differences into account. The scheme can also replace the use of timers so as to reduce network latency. The paper uses an analytical model to study the impact from forwarding distance of the reliable path under different circumstances such as vehicular density, vehicular transmission range and velocity variance.

Network virtualization enables diversified network architectures to coexist in a substrate network. Content-centric network (CCN), as one of the major proposals for the future network, can be deployed in the virtualized environment. However, the recent work that has attempted in this direction has not addressed issues concerning the unique resource usage of CCN in resource allocations during the embedding procedure when instantiating a virtual CCN (VCCN). The unique problem is the cache component, i.e., the content store, in CCN. This paper will develop a VCCN Mapping Algorithm (VCCNMA) that optimizes the performances of VCCN considering the content store request in addition to CPU and bandwidth. Since the resource allocation problem is NP-hard, this paper thus proposes a heuristic algorithm. Several sets of simulation experiments are performed to evaluate the acceptance ratio, the network cost, the storage utilization ratio and load balance. Results show that the algorithm can achieve better performances. Moreover, the paper also studies the tradeoffs between the network cost and the load balance.

Programming a network for innovative services or for function improvements has never been easier using Software-Defined Networking (SDN). However, the programming tasks can also be significantly complicated by the asynchrony of data plane states and complexities of service control states. In order to reduce the complexity for programming a network service in Distributed Control Plane of SDN, we propose a proGRAmming Control (GRACE) layer as a generic solution, which provides two key features, namely, reconfigurability and reusability. Their implementations deal with aforementioned challenges, thus to achieve the consistency of the data plane states and the reusability of the service control states at the distributed controllers. This paper introduces the reconfigurability and reusability with their design goals and their impact on the programmability of DCP. We further use two popular network services, ICN (Information-Centric Networking) and CDN (Content Distribution Networks) to illustrate these concepts. NS-3 simulations and PlanetLab emulations are conducted to show the advantage of using the GRACE layer for ICN and CDN. Results show that the ICN Interest delay is reduced by 19.6% and CDN request delay is reduced by 81% in extremely harsh network conditions.

Various solutions have been proposed to enable mobile users to access location-based services while preserving their location privacy. Some of these solutions are based on a centralized architecture with the participation of a trustworthy third party, whereas some other approaches are based on a mobile peer-to-peer (P2P) architecture. The former approaches suffer from the scalability problem when networks grow large, while the latter have to endure either low anonymization success rates or high communication overheads. To address these issues, this paper deals with an enhanced dual-active spatial cloaking algorithm (EDA) for preserving location privacy in mobile P2P networks. The proposed EDA allows mobile users to collect and actively disseminate their location information to other users. Moreover, to deal with the challenging characteristics of mobile P2P networks, e.g., constrained network resources and user mobility, EDA enables users (1) to perform a negotiation process to minimize the number of duplicate locations to be shared so as to significantly reduce the communication overhead among users, (2) to predict user locations based on the latest available information so as to eliminate the inaccuracy problem introduced by using some out-of-date locations, and (3) to use a latest-record-highest-priority (LRHP) strategy to reduce the probability of broadcasting fewer useful locations. Extensive simulations are conducted for a range of P2P network scenarios to evaluate the performance of EDA in comparison with the existing solutions. Experimental results demonstrate that the proposed EDA can improve the performance in terms of anonymity and service time with minimized communication overhead.

Human mobility, hence the movement pattern of mobile devices, often confines to relatively local geographic areas. Such a movement pattern reduces the opportunities for a message to be disseminated to a more global geographical region using the encounter-based “store-carry-forward” routing approach. On the other hand, different local areas often overlap to cover the entire region. A feasible communication architecture to help message dissemination is to deploy static storage-and-communication devices at those overlapping areas to serve as relays between the local areas. In this paper, we introduce the method to derive the simulation model for this heterogeneous network from contact trace and GPS trace of buses. Our main focus is to model communication properties between the static nodes and the mobile nodes. Typically, they are time-varying link delays formed by a collection of multiple mobile nodes. We further use a Markovian model to describe the time dependency among link delays at each static nodes and use the states to develop a network model for simulation. In the paper, we present simulation results to validate the reproduction of the mobility with the original traces by comparing routing performance. We show that the proposed network model can be used for performance evaluations with inherited realistic. The contributions of this work reside in the reproducibility to the real world traces and its flexibility in configurations. Further, it is the first simulator that enables to produce contact graph for a heterogeneous network with time-varying link properties. Its ability goes beyond simply calculating encounter events, but is well suitable for protocol evaluation in opportunistic networks, mobile social networks and delay tolerant networks.

Very often, network users expect to access services relevant to their locations, whilst preserve their privacy without disclose their exact locations. The well-known privacy preserving method is the spatial cloaking technique where exact user locations are blurred into a cloaked region to meet the privacy requirement, e.g. k-anonymity. Most of current solutions are designed with a centralized architecture in mind and rely on a third trustworthy party, i.e. a location anonymizing server (LAS). Unfortunately, these solutions cannot be directly applied to the mobile peer-to-peer (P2P) networks where no centralized servers are possible. In this paper, we present a dual-active spatial cloaking algorithm for mobile P2P networks. The key difference between the suggested algorithm and two existing algorithms, on-demand and proactive, is that: our algorithm allows peers not only actively collect but also actively disseminate location information to others. The three approaches are assessed through extensive simulation experiments for a range of P2P network scenarios. The experimental result shows that the dual-active approach uses the least anonymizing time and has the best anonymization success rate at the price of acceptable communicating cost.

A dissatisfaction appears to permeate the process of educating computer science students. Both students and instructors seem uninspired in the classroom, resulting in many attempts to enliven, freshen, and improve the experience. These attempts show efficacy, but the pace of improvement is slow. 100 Problems (100P) is an innovative guided discovery curriculum in which students are freed from the classroom and instead work on 100 concept- and research-related problems throughout their undergraduate careers. The 100 problems guide the students to discover the fundamental knowledge and skills required of a graduate of the degree program. Each student is free to create an individualized mode of learning and discovery. As such, the curriculum fosters deep learning among students and challenges students' intellectual growth. In this paper we introduce the 100P curriculum, describe the 100P course format and our experiences offering courses in this format, and report our early findings.

Deploying the static wireless devices (throw-boxes) at certain locations can help message dissemination among mobile nodes in delay tolerant networks. The mobile nodes traveling between throw-boxes form network links that carry the temporally stored messages at one box to another. However, the aggregated mobility between pairs of boxes reveals a time-dependent nature on its link delay (travel time) and link loading capacity (buffer size). The state-of-art DTN routing protocols do not address the challenge of combined delay and capacity with time-dependent links. In this paper, we tackle this challenge by introducing a capacity-aware routing protocol that is able to search the shortest path that considers the time-varying delay and capacity of the virtual links. We use a Markov Chain to model the evolution of the real-time link delay and capacity, and use the Markov Chain states to help derive the forwarding decision and routing policy. In evaluating the capacity-aware routing scheme, we use a network graph with the virtual links extracted from the contact trace. The simulations validate the advantages of the proposed routing strategy.

In this paper we analyze the security architecture of ProtoGENI. ProtoGENI is a prototype control framework implementation of GENI (Global Environment for Network Innovations). We perform a variety of experiments in an effort to identify potential vulnerabilities presented in the current implementation. We classify our attacks into three types: data plane to data plane, data plane to control plane, and data plane to Internet. Our results indicate the potential for a breach of confidentiality and availability internally within ProtoGENI, as well as risks to external Internet. We make suggestions outlining possible defense strategies to improve ProtoGENI security and aid in future development.

We propose a vehicular network trust model that integrates cryptography-based entity trust and email-based social trust. The entity trust provides security protections such as origin integrity, data integrity, and confidentiality. The social trust provides a level of belief on the data transmitted by an entity. To achieve the email-based social trust, we require each user to run an automated agent that performs trust evaluation checks and processes trust checking requests. The requests are from their highly trusted contacts or through a trusted proxy server maintained by the email service provider. We utilize identity-based cryptography (IBC) to integrate entity trust and social trust. This allows us to use a unique identity (e.g., an email address) for each entity. Further, we use the IBC based attribute based cryptography to develop secure group communications in vehicular networks. Finally, we present research challenges and potential research directions to extend this work.

In this paper, we study the transition phase in the network connectivity. We focus on the critical time points that mark the network transformation from partition to connected state following a growth of node density. The percolation theory is used to analyze the relationship between the density increase process and the connectivity transition. Specifically, we derive the lower bound and the upper bound of critical density points against node transmission range. We also use three growth functions of node density to obtain the first connection time and the total connection time which denote the critical points when the node densities reach the lower bound and upper bound of critical value respectively. The simulation demonstrates the evolution of network in terms of the connectivity and gives the connection times with three different growth models.

In delay tolerant network, message delivery can be inspired by biological communication models in realizing encountering and delivering. One way of communications can be through "thrown box" where the messages can be left and collected by different nodes in mimicking pheromone-based communications. In thrown box based model, the box is viewed as message relay and the delivery rate is enhanced by spreading a message at as many boxes as possible. Both the life time of message left at the boxes and message leaving preference will have a significant influence on the latency and delivery ratio in message dissemination. In this paper, we model the latency problem as discrete time Markov Chain and further derive the time distribution of first contact between the message and collector. By varying the parameters of message leaving probability and initial environment condition, the latency related results are studied.

Due to the self organizing characteristic of Ad Hoc network, it is difficult to adopt traditional delay measurement techniques in a multi hop Wireless Mesh network (WMN). This problem is much more complicated in multi-radio environment because of the mutual interferences that contribute significantly to the overall delay. We present an experimental methodology to obtain an estimate of average intra-node delay and inter-node delay for packets of variable payload size in both single radio and multi-radio environment without the constraint of clock synchronization between the nodes. Our results provide insights on comparing performances between single and multi-radio environment with some interesting findings like periodic nature for intra-node delay with oscillating frequency distribution. Finally our statistical analysis validates the linear relationship between end to end delay, intra-node delay and inter-node delay.

Wireless network access from moving vehicles can be challenged by many factors such as connection opportunities, mobility, handshake phase, and data sizes, etc. The handshake time and transmission rate can be influenced differently in vehicle-to-roadside networks than a static wireless LAN access. The radio signal strength changes and Doppler shift occur when the vehicle is moving. Switching among APs could cause significant connection stale, which could have a major impact on the handshake phase and transmission rate. The purpose of our paper is to enhance the understanding of these influential factors and study the feasibility of mobile vehicle access for a hybrid environment that contains sparse and dense access point deployments. Experiment data was collected in a moving vehicle, which traveled around the campus of the university. In the data analyze part, the above factors are analyzed for packet inter-arrival time, response time and transmission rate; Our main results are focused in security enabled protocols such as HTTPS and SSH, as well as TCP file transmission. Our data shows that IEEE 802.11g is still weak in supporting mobile vehicle access to the Wireless LAN. We expect that IEEE 802.11p, designed specifically for vehicle networks, can provide better mobile services.

The security issue regarding to worm propagation that exploits geographic proximity of wireless enabled devices has raised attentions in recent years. Early work has modeled worm propagation through directly infecting neighboring nodes, e.g., wireless routers and Bluetooth networks. However, there remains new potential wireless connection topology that can assist the spread of worm in a covert way and threat the cyberspace. In this paper, we study a potential worm epidemic pathway that lies in the densely overlapped wireless metropolitan networks and covers large geographic areas. Specifically, the overlapped footprints of neighboring access points can create hidden connections for worms to propagate across the entire wireless network. We present a novel analytical model to analyze the spread speed of this type of worm. The constraints of the nodes within the overlapped footprints, the boundaries set aside by the access point associations, network topology, and density of both access points and users are considered in the model. We also present methods to obtain estimations about propagation delays in an access point coverage and to generate numerical results based on the model. In evaluation, real maps of access points are used to simulate worm propagation and validate the model. The results call for research on detection and defense solutions against worm propagation in wireless networks.

Existing channel assignment algorithms designed for multi-radio multi-channel wireless mesh networks (MRMC-WMN) mainly deal with orthogonal or nonoverlapped channels. But in reality, the limited availability of orthogonal channel is a major issue where the network is very dense in terms of inter-nodal distances. On the other hand, partially overlapped channels (POC) are currently considered as a great potential for increasing the number of simultaneous transmissions and eventually upgrading the network capacity; especially in case of MRMC-WMN. In this paper, we address the limited orthogonal channel problem by exploring the usable POCs. The key technique lies in the fact that the interference between adjacent channels has to be considered intelligently in order to increase the overall capacity. Our contributions include a new interference model I-Matrix that helps selecting channels with less interference and a POC based channel assignment algorithm. We evaluate the performance of our POC based algorithm in terms of capacity by comparing with the one using only orthogonal channels. Our results show capacity improvement as the increased link assignments at an average of more than 15 percent.

Abstract Anonymity is an important security aspect of wireless communications and has continuously attracted significant attention. Implementing anonymity of mobile users not only protects their privacy but also reduces the chances of attacks based on impersonation; therefore security can be improved. Untraceability is a related issue to anonymity. If a user is traceable, its hidden identity can be revealed through profiling the activities associated to a user. In this paper, we conduct a survey on anonymity issues of wireless communication systems. We first discuss general issues of anonymity in wireless communication systems. Then we survey some protocols in the literature, which are designed for wireless mobile systems as well as wirelessad hocnetworks. Copyright © 2008 John Wiley & Sons, Ltd.

Abstract The open nature of wireless medium has left wireless communications vulnerable to various privacy attacks. Much research work has been proposed to protect the identity anonymity of communicating parties, the anonymity of network routes and the location privacy of the message source and destination. However, with the advent of new radio identification and localization techniques, more advanced privacy attacks are possible. We describe a new privacy attack in which the adversary tries to infer the itineraries of the nodes in the network. To protect itinerary privacy, we design an algorithm, called$\Delta$ ‐camouflaging mobility algorithm, which changes the original motion segments of a node into$\Delta$ ‐shaped camouflaging paths. Itinerary privacy, correspondent privacy, and route privacy are closely related so we propose a comprehensive anonymous routing scheme, calledMARS, to protect these privacy goals. MARS exploits camouflaging mobility to protect itinerary privacy and usesmotion pseudonymsgenerated from the camouflaging mobility to protect correspondent privacy and route privacy without using cryptography. Our analysis results show that$\Delta$ ‐camouflaging mobility algorithm is cost‐effective, which can significantly reduce the itinerary exposure probability at a small cost of extra travel distance. Moreover, our network simulation results illustrated that MARS anonymous routing scheme and$\Delta$ ‐camouflaging mobility algorithm did not reduce network layer performance. Copyright © 2009 John Wiley & Sons, Ltd.

We present a collaborated camouflaging mobility algorithm to protect mobile hosts' mobility privacy. Our algorithm alters a mobile host's straight moving paths into Delta-shaped camouflaging paths, which cause its wireless transmissions to be distributed over a large area, and hence, reduce the probability of generating traceable wireless transmissions. Furthermore, on the premise of not affecting the mobile hosts' itineraries, our collaborated mobility algorithm clusters the motion paths of mobile hosts to make it difficult for an adversary to identify the mobile hosts. We model the objective of maximizing mobility privacy and minimizing the overhead (e.g. the extra travel distance) as a nonlinear constrained optimization problem and use the solution to the optimization problem as the collaborated mobility. Lastly, we analyze the calculation time of the collaborated camouflaging mobility and conduct simulations to evaluate the privacy improvements brought by the collaborated camouflaging mobility algorithm compared with non-covered mobility.

In this paper, we propose a distributed online multichannel assignment and routing algorithm called LOAM. Using LOAM algorithm, a node in the network assigns channels for the incoming traffic flows and forwards them based on the channel usage information of its nearby nodes. We also present a model to analyze the throughput of multichannel networks and prove LOAM can achieve more than a fraction of the optimal throughput. Furthermore, we compare the achievable throughput of LOAM with a centralized offline channel assignment algorithm in average cases considering different channel rate and traffic load scenarios, the results of which demonstrate that LOAM can achieve more than 90% of theoretical maximum throughput and has a more balanced load distribution. Finally, we evaluate LOAM in a realistically simulated 802.11a wireless multihop network, compared with a random channel assignment algorithm. The simulation results show that LOAM can deliver up to 25 percent more messages with a shorter delivery latency.

Because of easy accessible medium in wireless networks, use of these wireless networks in military applications poses several security issues. Likewise, in the business field, despite the emerging static wireless Internet access, the same security issues remains. On example is the passive attack in which attackers attempt to overhear network communications from the outside. Confidentiality can be further divided into two categories, namely, data confidentiality and traffic confidentiality. In this paper, for improving traffic confidentiality, we propose two anonymous routing algorithms, called randomized routing algorithm and probabilistic penalty-based routing algorithm. Both algorithms aim to differentiate routing paths to the same destination enhancing anonymity of the network traffic. We provide simulation results and demonstrate how much these two algorithm disperse routing paths in a network.

The privacy of wireless communications is becoming an important issue due to the open nature of wireless medium. Much research work has been proposed to address the anonymity of communicating parties, the location privacy of the message source and destination, and the privacy of the network routing paths. However, with the advent of new radio identification and localization techniques, more advanced privacy attacks are possible. We describe a new privacy attack in which the adversary tries to infer the itineraries of the nodes in the network. To protect itinerary privacy, we design an algorithm, called the Delta-mobility camouflaging algorithm, which can be applied upon any mobility model by changing the original motion segments into Delta-shaped camouflaging paths. Our analysis results show that the Delta-mobility camouflaging algorithm is cost-effective, which in most cases decreases the itinerary exposure probability more than 80% at a cost of less than 3% extra travel distance.

Abstract Relative location information helps build vehicle topology maps. Such maps provide location information of nearby vehicles to drivers. In building a vehicle topology, one must consider various attacks on vehicular networks. Also the localization system should protect the drivers' identity and make it difficult for the adversary to track vehicles. Many techniques have been proposed for relative positioning and location verification. Due to the high speed and the strict security requirements, the existing relative positioning and location verification techniques are not directly applicable to vehicular networks. Hence, we present a scheme called Privacy‐preserving Secure Relative Location Determination (P‐SRLD), which securely determines the relative locations of a set of wirelessly connected vehicles based on the relative locations of each vehicle's surrounding vehicles. P‐SRLD uses cryptographic keys to authenticate location messages and vehicle's cryptographic pseudonym to identify the vehicle to protect vehicle's driver's privacy. To defend against Sybil attacks, P‐SRLD employs registration and relative location message verification mechanisms. It defends wormhole and blackhole attacks by probabilistically monitoring losses of relative location messages. Analysis and simulation results show that P‐SRLD is lightweight and is resilient to Sybil, wormhole and some other attacks. Copyright © 2008 John Wiley & Sons, Ltd.

In this paper, we address the problem of destination anonymity for applications in mobile ad hoc networks where geographic information is ready for use in both ad hoc routing and Internet services. Geographic forwarding becomes a lightweight routing protocol in favor of the scenarios. Traditionally the anonymity of an entity of interest can be achieved by hiding it among a group of other entities with similar characteristics, i.e., an anonymity set. In mobile ad hoc networks, generating and maintaining an anonymity set for any ad hoc node is challenging because of the node mobility, consequently the dynamic network topology. We propose protocols that use the destination position to generate a geographic area called an anonymity zone (AZ). A packet for a destination is delivered to all the nodes in the AZ, which make up the anonymity set. The size of the anonymity set may decrease because nodes are mobile, yet the corresponding anonymity set management is simple. We design techniques to further improve node anonymity and reduce communication overhead. We use analysis and extensive simulation to study the node anonymity and routing performance, and to determine the parameters that most impact the anonymity level that can be achieved by our protocol.

We draw an analogy of biological cyanide poisoning to security attacks in self-organizing mobile ad hoc networks. When a circulatory system is treated as an enclosed network space, a hemoglobin is treated as a mobile node, and a hemoglobin binding with cyanide ion is treated as a compromised node (which cannot bind with oxygen to furnish its oxygen-transport function), we show how cyanide poisoning can reduce the probability of oxygen/message delivery to a "negligible" quantity. Like modern cryptography, security problem in our network-centric model is defined on the complexity-theoretic concept of "negligible", which is asymptotically sub-polynomial with respect to a pre-defined system parameter x. Intuitively, the parameter x is the key length n in modern cryptography, but is changed to the network scale, or the number of network nodes N, in our model. Based on this new analytic model, we show that RP (n-runs) complexity class with a virtual oracle can formally model the cyanide poisoning phenomenon and similar network threats. This new analytic approach leads to a new view of biological threats from the perspective of network security and complexity theoretic study.

Delay-Tolerant network (DTN) is a network in which no simultaneous end-to-end path exists. And the messages delivered in the DTN usually have large delivery latency due to network partition. These special characteristics make DTN routing a challenging problem. In this paper, we propose a DTN routing protocol SMART. SMART uses travel companions of the destinations (i.e. nodes that frequently meet the destination) to increase the delivery opportunities. In the first phase of SMART, a fixed number of copies of a message are injected into the network to forward the message to the companions of the destination. In the second phase of SMART, a companion of the destination only forwards the message to a fixed number of the destination’s companions. Our analysis and simulation results show that SMART has a higher delivery ratio and smaller delivery latency than opportunistically controlled-flooding schemes and has a significantly smaller routing overhead than pure flooding schemes.

Location information of users can now be collected from most wireless communication using advanced wireless location tracking techniques. Providing location information can be advantageous in some situations. However, there are instances, where it may be critical to protect the location of the individual. Several protection strategies, such as periodically updating interface identifiers, have been proposed so that an adversary cannot track mobiles in long-term movements. In this paper, we introduce a new strategy, DMAS (Dynamical Mac Assignment with Shuffle), in which the mobile client dynamically exchanges its assigned Mac addresses with others.We present a security analysis to show this scheme can greatly secure a client's location privacy.

We propose a secure data transmission scheme that takes advantage of node mobility. The scheme is based on the observation that due to mobility, messages sent at different times are routed through different intermediate nodes. The source divides a message into multiple shares and sends these shares at different times. The destination combines enough shares to recover the original message. Due to mobility, it is high unlikely that an intermediate node is able to collect enough shares. The feasibility of this scheme is analyzed and simulated.

In this paper, we propose a novel dynamic Mac address assignment and exchange strategy to reduce location disclosure risks. The use of dynamic Mac addresses in a local area network (LAN) is feasible since the address uniqueness needs only to be handled within the LAN. Though each node has a universal Mac address assigned by the manufacturer, a local unique Mac address is sufficient for the node to participate in communications. Our proposed strategy includes three major schemes. The first is to assign a Mac address to the client using the same idea as the IP address assignment. Next, a Mac addresses shuffle is conducted among the clients in the wide local area network (WLAN) without exposing any exchange relations or frequently disrupting current connections. Lastly, dummy messages are sent from the wireless client to cover others during idle. In current wireless networking, a client must communicate with an access point (AP) and authorization server in order to obtain authorization to access a local wireless network. In our scheme, we do not use a node's real physical Mac address when associating with an AP. Instead, there is a public special Mac address broadcast in the beacon messages which will be chosen as the source Mac address in the association request frame. As a result, the user will never expose its identifier when associated with the AP. The client also keeps a variant silent period as a defense against a correlation attack.

Introducing node mobility into the network also introduces new anonymity threats. This important change of the concept of anonymity has recently attracted attentions in mobile wireless security research. This paper presents identity-free routing and on-demand routing as two design principles of anonymous routing in mobile ad hoc networks. We devise ANODR (ANonymous On-Demand Routing) as the needed anonymous routing scheme that is compliant with the design principles. Our security analysis and simulation study verify the effectiveness and efficiency of ANODR.

The data availability in a data grid system is complicated by node failure, data catalog error and an unreliable network. To improve the job response time and data availability, data is typically replicated in large scale data-massive applications. However, the dynamic behavior of a Grid user makes it difficult to determine where and how to make data replications to meet the system availability goal. Some strategies for data replication have previously been proposed, but they assumed unlimited storage for replicas. In this paper, we present two new metrics to measure the system data availability. We then model the system availability problem assuming limited replica storage and transfer this to a classic optimal problem. We present four strategies for limited replica storage that maximize the data availability by minimizing the data missed rate (MinDmr), based on a file weight and prediction function. Our simulation on the OptorSim shows our MinDmr algorithm achieves better performance overall than others in term of data availability. Results indicate the performance of MinDmr is always better than others with varying prediction functions, job schedulers and file access patterns, as far as the data missing rate is concerned.

Under security threats, today's networks are being made to be intrusion tolerant. In a large scale, services are continuing (at a degraded level) while compromising and recovering are both progressing. One of the key problems in the restoration procedure regards to the resource allocation strategies, typically a minimized total cost concerning both service loss and resource expense. In this paper, we investigate the achievable minimal total cost and corresponding resource allocation strategy for different situations. The situations include nonlinear relationship between resource allocation rate and the restoration rate, and its variant when time factor is concerned. We present cost models and numerical results. The results show the impact from various system parameters on the critical conditions for a successful system restoration and the minimal cost. An important result of our study suggests that tight operational region exists under certain conditions.

Vehicular networks will become an important component for information accesses in one's daily life. A vehicular network provides a vehicular user not only chances to communicate with peer vehicles but also to use Internet through roadside access points (APs). During a trip a vehicular user could roam across multiple APs either belong to their home wireless domain or to domains owned by different authorities. This poses challenges on privacy and network performance to the current public wireless network access protocols. In this paper we explore an idea that shifts the paradigm of authentication that goes back to home networks to a paradigm of authentication that performs at the APs. We propose three authentication schemes in realizing the idea. These schemes are designed for preserving user's identity and location privacy. They also greatly reduce response time for authentication when roaming. The paper then analyzes the security and privacy properties of these schemes as well as the efficiency of them

Mobile ad hoc networks require anonymous communications in order to thwart new wireless passive attacks; and to protect new assets of information such as nodes' locations, motion patterns, network topology and traffic patterns in addition to conventional identity and message privacy. In particular, in wireless ad hoc networks mobile nodes must rely on ad hoc routing to keep network functional for communication. The transmitted routing messages and cached active routing entries leave plenty of opportunities for eavesdroppers. To address the new challenges, several anonymous routing schemes have been proposed recently. However, in various network scenarios, how the different cryptographic operations impact the routing performance remains unclear. In this paper we investigate the impact from cryptographic operations needed for the anonymous features. The overhead considered includes both increased control packet size and prolonged processing delay. The protocols taken into account include ANODR, AnonDSR, ASR, MASK, and SDAR. We present results based on extensive simulation study. We use the standard/unprotected on-demand scheme AODV in the comparison to show how much cost is paid by each anonymous on-demand scheme. Our simulation study shows that various design choices in anonymous routing indeed trade performance with anonymity protection. We conclude that extensive performance study is needed to evaluate the practicality of any enhancement of these proposed schemes and any new anonymous routing schemes

Abstract Privacy in mobile ad hoc networks has new semantics in addition to the conventional notions for infrastructure networks. Mobility enabled by wireless communication has significantly changed privacy issues and anonymity research in many ways. In particular, mobility requires ad hoc routing schemes to transmit messages frequently in an open wireless medium. The routing traffic facilitates adversaries in conducting various attacks threatening the network security and privacy. In this work, we focus on passive routing attacks. We present an extensive study on new anonymity threats and classify the corresponding security demands into three new categories: (1)venue anonymity; (2)privacy of ad hoc network topology; and (3)privacy of motion pattern. These new aspects are all introduced by mobility and left unaddressed in fixed infrastructure. This leads us to investigate new design principles. Our study suggests thaton‐demand routing,identity‐free routing, andneighborhood traffic mixingare better design choices to defend against the new anonymity threats in mobile networks. The paper also demonstrates through examples on the visualization of the mobile anonymity attacks and on the quantification of the effectiveness of the attacks. Copyright © 2006 John Wiley & Sons, Ltd.

Introducing node mobility into the network also introduces new anonymity threats. Nevertheless, this important change of the concept of anonymity has not been studied in state-of-art network security research. This paper presents the needed study. Then we show that anonymous routing in mobile networks has great impact on routing performance. We calls for the attention to devise new and efficient anonymous routing schemes for mobile ad hoc networks.

Mobile ad hoc networks (MANETs) are vulnerable to routing attacks, especially attacks launched by non-cooperative (selfish or compromised) network members and appear to be protocol compliant. For instance, since packet loss is common in mobile wireless networks, the adversary can exploit this fact by hiding its malicious intents using compliant packet losses that appear to be caused by environmental reasons.In this paper we study two routing attacks that use non-cooperative network members and disguised packet losses to deplete ad hoc network resources and to reduce ad hoc routing performance. These two routing attacks have not been fully addressed in previous research. We propose the design of "self-healing community" to counter these two attacks. Our design exploits the redundancy in deployment which is typical of most ad hoc networks; Namely, it counters non-cooperative attacks using the probabilistic presence of nearby cooperative network members.To realize the new paradigm, we devise localized simple schemes to (re-)configure self-healing communities in spite of random node mobility. We develop a general analytic model to prove the effectiveness of our design. Then we implement our secure ad hoc routing protocols in simulation to verify the cost and overhead incurred by maintaining the communities. Our study confirms that the community-based security is a cost-effective strategy to make off-the-shelf ad hoc routing protocols secure.

Routing protocols for mobile ad-hoc networks have been evaluated extensively through simulation because various network conditions can be easily configured, tested, and replicated across different schemes in simulation than in a real system. Recently, some of these schemes have been implemented in academic, industry and defense testbeds. This gives researchers an opportunity to validate their simulation results with actual implementations. In this paper we report the lessons learned from the implementation of LANMAR (Pei et al. (2000)), a scalable routing protocol that was developed at UCLA as part of large-scale ad hoc network architecture for autonomous unattended agents under ONR support. LANMAR is designed to provide efficient, scalable routing in large ad-hoc wireless networks that exhibit group mobility. In this paper we describe the implementation of this protocol in Linux environments and report on experimental results based on this implementation. The results and lessons from these experiments have enriched our understanding of the LANMAR protocol and its interaction with the other layers and the environment, paving the way to protocol refinements and more efficient implementations.

In hostile environments, the enemy can launch traffic analysis against interceptable routing information embedded in routing messages and data packets. Allowing adversaries to trace network routes and infer the motion pattern of nodes at the end of those routes may pose a serious threat to covert operations. We propose ANODR, an anonymous on-demand routing protocol for mobile ad hoc networks deployed in hostile environments. We address two closely related problems: For route anonymity, ANODR prevents strong adversaries from tracing a packet flow back to its source or destination; for location privacy, ANODR ensures that adversaries cannot discover the real identities of local transmitters. The design of ANODR is based on "broadcast with trapdoor information", a novel network security concept which includes features of two existing network and security mechanisms, namely "broadcast" and "trapdoor information". We use simulations and implementation to validate the effectiveness of our design.

In ad hoc, multihop wireless networks the routing protocol is key to efficient operation. The design of an ad hoc routing protocol is extremely challenging because of mobility, limited power, unpredictable radio channel behavior and constrained bandwidth. As the network grows large, two additional challenges must be faced: increasing node density, and large number of nodes. High density (i.e., a large number of neighbors within radio range) leads to "superfluous" forwarding of broadcast control messages. Large network size leads to large routing tables and high control traffic overhead. The two aspects are related and they both undermine the scalability of routing protocols. In this paper, we address scalability for a specific class of routing protocols, namely, proactive link state routing protocols. Link state protocols are desirable in many applications because of low access delay, ability to include QoS criteria in path selection, support of alternate routes, etc. Yet, these protocols are most affected by density and large scale. In the paper, we propose two techniques to overcome density and large scale, namely passive clustering and landmark routing. We compare via simulation our proposed solutions to other existing scalable schemes.

A mobile ad hoc network (MANET) is usually assumed to be homogeneous, where each mobile node shares the same radio capacity. However, a homogeneous ad hoc network suffers from poor scalability. Recent research has demonstrated its performance bottleneck both theoretically and through simulation experiments and testbed measurement Building a physically hierarchical ad hoc network is a very promising way to achieve good scalability. In this paper, we present a design methodology to build a hierarchical large-scale ad hoc network using different types of radio capabilities at different layers. In such a structure, nodes are first dynamically grouped into multihop clusters. Each group elects a cluster-head to be a backbone node (BN). Then higher-level links are established to connect the BN into a backbone network. Following this method recursively, a multilevel hierarchical network can be established. Three critical issues are addressed in this paper. We first analyze the optimal number of BN for a layer in theory. Then, we propose a new stable clustering scheme to deploy the BN. Finally LANMAR routing is extended to operate the physical hierarchy efficiently. Simulation results using GloMoSim show that our proposed schemes achieve good performance.

We present an enhanced version of the routing protocol, Landmark Ad Hoc Routing (LANMAR). LANMAR combines the features of Fisheye State Routing (FSR) and Landmark routing. The enhanced version features landmark election to cope with the dynamic and mobile environment. Other advantages of LANMAR include the use of landmarks for each logical group (e.g., a team of co-workers at a convention or a tank battalion in the battlefield) in order to reduce routing update overhead in large networks, and the exchanging of neighborhood link state only with neighbors. When the network size grows, remote groups of nodes are "summarized" by the corresponding landmarks. As a result, each node will maintain accurate routing information about immediate neighborhood; at the same time it will keep track of the routing directions to the landmark nodes and thus, to remote groups. Simulation experiments show that the enhanced version suffers some performance degradation at steady state because of election overhead. However, it still provides an efficient and scalable routing solution in a mobile, ad hoc environment. Moreover, the election provides a much needed recovery from landmark failures.

In this paper, we present a novel routing protocol for wireless ad hoc networks-landmark ad hoc routing (LANMAR). LANMAR combines the features of fisheye state routing (FSR) and landmark routing. The key novelty is the use of landmarks for each set of nodes which move as a group (e.g., a team of co-workers at a convention or a tank battalion in the battlefield) in order to reduce routing update overhead. Like in FSR, nodes exchange link state only with their neighbors. Routes within the fisheye scope are accurate, while routes to remote groups of nodes are "summarized" by the corresponding landmarks. A packet directed to a remote destination initially aims at the landmark; as a gets closer to the destination it eventually switches to the accurate route provided by fisheye. Simulation experiments show that LANMAR provides efficient and scalable routing in large, mobile, ad hoc environments in which group mobility applies.

Multi-layer ad hoc wireless networks with UAVs is an ideal infrastructure to establish a rapidly deployable wireless communication system any time any where in the world for military applications. In this tactical environment, information traffic is quite asymmetric. Ground fighting units are information consumers and receive far more data than they transmit. The up-link is used for sending requests for information and some networking configuration overhead with a few kilobits, while the down-link is used to return the data requested with megabits size (e.g. multimedia file of images and charts). Centralized intelligent channel assigned multiple access (C-ICAMA) is a MAC layer protocol proposed for ground backbone nodes to access UAV (unmanned aerial vehicle) to solve the highly asymmetric data traffic in this tactical environment. With it's intelligent scheduling algorithm, it can dynamically allocate bandwidth for up-link and downlink to fit the instantaneous status of asymmetric traffic. The results of C-ICAMA is very promising, due to the dynamic bandwidth allocation of asymmetric up-link and down-link, the access delay is tremendously reduced.

Large homogeneous ad hoc wireless networks have a problem: the bandwidth available to a mobile user decreases as the number of nodes in the network increases. Using the embedded ad-hoc networking mechanism, nodes are able to transport packets across the network in a multihop fashion. An embedded mobile backbone is dynamically constructed to form a 2-level physical heterogeneous multihop wireless network. These backbone nodes provide two critical functions: (1) direct communication between neighboring cluster heads; and (2) efficient route discovery in HSR. With the broadcast feature of unmanned aerial vehicle (UAV), the link state can be broadcast to backbone nodes instead of "flooding" on the level 2. Thus, the routing overhead can be tremendously reduced, and the throughput will be improved. We modified hierarchical state routing (HSR) to have an intelligent selection algorithm to reduce the system latency caused by the long propagation delay of the UAV channel. The performance of the system is evaluated through simulation experiments.

In this paper we present a hierarchical routing protocol in a large wireless, mobile network such as found in the automated battlefield or in extensive disaster recovery operations. Conventional routing does not scale well to network size. Likewise, conventional hierarchical routing cannot handle mobility efficiently. We propose a novel soft state wireless hierarchical routing protocol-Hierarchical State Routing (HSR). We distinguish between the "physical" routing hierarchy (dictated by geographical relationships between nodes) and "logical" hierarchy of subnets in which the members move as a group (e.g., company, brigade, battalion in the battlefield). HSR keeps track of logical subnet movements using home agent concepts akin to Mobile IP. A group mobility model is introduced and the performance of the HSR is evaluated through a detailed wireless simulation model.

The trace image of moving object is directly obtained from video signal and stored in one frame memory. From the trace image, one can measure the concentration, velocity, and acceleration of objects. The morphology of each trace can also be analyzed. Because only one frame of trace image is needed, it is less expensive, but more automatic, so it can be wide used in many fields. An application example of semen analysis is given.>