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In TDD massive MISO systems, user equipments (UEs) send channel measurement pilots to the BS for beamforming. Frequently sending these pilots, although improving beamforming, could consume significant communication resources. In this letter, we investigate how frequent these pilots should be sent for each UE so as to increase overall throughput performance for TDD massive MISO downlink. This real-time resource allocation problem is challenging due to non-trivial performance metric and boundary conditions. Assuming that instantaneous speed and location information of UEs can be obtained by the BS, we propose a reinforcement learning framework in which the BS acts as a learning agent to decide pilot intervals. Simulation results show that, for this multi-terminal setting where UEs compete for resources, using this centralized reinforcement learning framework, performance can be improved by choosing pilot intervals and transmission rates based on the UE information.

We investigate downlink scheduling in two-hop relay access networks with a central controller. To address the time-varying nature of wireless channels, a channel-aware scheduling scheme is proposed to exploit both spatial and multihop diversity. Given instantaneous channel state information, scheduling decisions are made at every time slot based on the designed priority indexes. The proposed scheme improves throughput and ensures fair transmission among all the active mobile stations in the system. In addition, with optimized scaling factors, the proposed scheme is shown to be close to Pareto-optimal.

With the shortage of cybersecurity professionals, there is a critical need to train more young-generation cybersecurity professionals to fill the gap. In this work, we designed interactive activities that make abstract cybersecurity concepts more tangible by using exciting new mixed reality (MR) technology to teach cybersecurity skills and raise the potential interest in cybersecurity careers for middle school students. We plan to analyze the immersive experience, situational interest, and workload after the experiment to study the participants' learning performance and user experience.

Attribute Based Encryption (ABE) has emerged as an informtion-centric public key cryptographic system which allows a data owner to share data, according to an access policy, with multiple data users based on the attributes they possess, without knowing their identities. In the original ABE schemes, a central authority administrates the system and issues secret keys to data users based on their attributes and both the owner and users need to trust a specific CA. However, in certain real-world applications, the data users would not trust anyone but themselves. For such situations, we introduce a new decentralization model of ABE, termed Data User-based ABE (DU-ABE), which is managed jointly by the data users. DU-ABE is the first decentralized ABE scheme which replaces the authorities with the data users without employing any other extra entities.

The global Electronic Health Record (EHR) market is growing dramatically and has already hit $31.5 billion in 2018. To safeguard the security of EHR data and privacy of patients, fine-grained information access and sharing mechanisms are essential for EHR management. This paper proposes a hybrid architecture of blockchain and edge nodes to facilitate EHR management. In this architecture, we utilize attribute-based multi-signature (ABMS) scheme to authenticate user's signatures without revealing the sensitive information and multi-authority attribute-based encryption (ABE) scheme to encrypt EHR data which is stored on the edge node. We develop the blockchain module on Hyperledger Fabric platform and the ABMS module on Hyperledger Ursa library. We measure the signing and verifying time of the ABMS scheme under different settings, and experiment with the authentication events and access activities which are logged as transactions in blockchain., Comment: This paper is accepted to the Short Paper track by 2020 IEEE International Conference on Blockchain and Cryptocurrency (ICBC 2020)

Licensed-assisted access (LAA) of the long term evolution (LTE) has been standardized by the Third Generation Partnership Project (3GPP) in Release 13 to address the urgent issues of ever-increasing traffic demands in cellular systems. However, challenges arise for the efficient coexistence of Wi-Fi and LAA in the same unlicensed spectrum. In this paper, the impact of LAA's energy detection thresholds on such coexistence are investigated from the perspective of collisions occurring during downlink transmissions. To facilitate the efficient coexistence of Wi-Fi and LAA, a distributed algorithm is proposed to adaptively change the energy detection thresholds of LAA per user or per base station, so that the system encourages more concurrent transmissions without introducing too many collisions. Simulation results validate the effectiveness of the proposed adaptive algorithm.

The global Electronic Health Record (EHR) market is growing dramatically and expected to reach $39.7 billions by 2022. To safe-guard security and privacy of EHR, access control is an essential mechanism for managing EHR data. This paper proposes a hybrid architecture to facilitate access control of EHR data by using both blockchain and edge node. Within the architecture, a blockchain-based controller manages identity and access control policies and serves as a tamper-proof log of access events. In addition, off-chain edge nodes store the EHR data and apply policies specified in Abbreviated Language For Authorization (ALFA) to enforce attribute-based access control on EHR data in collaboration with the blockchain-based access control logs. We evaluate the proposed hybrid architecture by utilizing Hyperledger Composer Fabric blockchain to measure the performance of executing smart contracts and ACL policies in terms of transaction processing time and response time against unauthorized data retrieval., Accepted to Proc. of the IEEE 2nd International Conference on Blockchain (Blockchain-2019), Atlanta, USA

Attribute-based access control makes access control decisions based on the assigned attributes of subjects and the access policies to protect objects by mediating operations from the subjects. Authority, which validates attributes of subjects, is one key component to facilitate attribute-based access control. In an increasingly decentralized society, multiple attributes possessed by subjects may need to be validated by multiple different authorities. This paper proposes a multi-authority attribute-based access control scheme by using Ethereum's smart contracts. In the proposed scheme, Ethereum smart contracts are created to define the interactions between data owner, data user, and multiple attribute authorities. A data user presents its attributes to different attribute authorities, and after successful validation of attributes, obtains attribute tokens from respective attribute authorities. After collecting enough attribute tokens, a smart contract will be executed to issue secret key to the data user to access the requested object. The smart contracts for multi-authority attribute-based access control have been prototyped in Solidity, and their performance has been evaluated on the Rinkeby Ethereum Testnet., This paper has been accepted by ACM Proceedings of the 2019 International Conference on Blockchain Technology

In wireless networks such as those based on IEEE 802.11, packet losses due to fading and interference are often misinterpreted as indications of congestion by the congestion control protocol at higher layers, causing an unnecessary decrease in the data sending rate. For delay-constrained applications such as video telephony, packet losses may result in excessive artifacts or freeze in the decoded video. We propose a simple and yet effective mechanism to detect and reduce channel-caused packet losses by adjusting the retry limit parameter of the IEEE 802.11 protocol while taking into account the delay requirement of the traffic. Since the retry limit is left configurable in the IEEE 802.11 standard and does not require cross-layer coordination, our scheme can be easily implemented and incrementally deployed. Experimental results of applying the proposed scheme to a WebRTC-based real-time video communication prototype show significant performance gain compared to the case where the retry limit is configured statically.

Two-tiered wireless sensor and actor networks (WSANs) have been proposed to enhance network capabilities, where a set of resource-rich mobile nodes (termed actors ) form a connected backbone to relay sensing data from static sensors to the sink and sometimes are requested by sensors to perform a particular action. Such a two-tiered WSAN facilitates scalability and can efficiently reduce the energy consumption incurred by conventional hop-by-hop relaying via only sensors. However, relocating actors to achieve both connectivity and load balance is a challenge, especially when there is no location information of the nodes. Connectivity ensures that the actors are connected, whereas load balance ensures that actors collect and originate a similar amount of sensory data from the sensors. In this article, we formulate the Connected and Balanced Mobile Actor Relocation (CBMAR) optimization problem to address both connectivity and load balance and prove that the problem is NP-hard. We thus propose a dual-mode distributed actor relocation protocol that does not rely on any location information of nodes to relocate actors. The idea is to locally form virtual Voronoi cells of actors (termed covering cells ) based on the lower-tiered topology, where each actor locally recruits its own sensor members to form its own covering cell. By maintaining the covering cell, each actor locally relocates itself toward a sensor along the lower-tiered topology. Extensive simulation results show that the protocol can achieve both objectives of connectivity and load balance with low moving and communication overheads.

In today's WLANs, scheduling of packet transmissions solely relies on the collision and success a station may experience. To better support traffic differentiation in dense WLANs, in this paper, we propose a distributed reservation mechanism for the Carrier Sense Multiple Access Extended Collision Avoidance (CSMA/ECA) MAC protocol, termed CSMA/ECA-DR, based on which stations can collaboratively achieve higher network performance. In addition, proper Contention Window (CW) will be chosen based on the instantaneously estimated number of active contenders in the network. Simulation results from dense scenarios with traffic differentiation demonstrate that CSMA/ECA-DR can greatly improve the efficiency of WLANs for traffic differentiation even with large numbers of contenders., Comment: This work has been accepted by IEEE VTC 2018 Fall conference

The existing dynamic spectrum access network architecture fails to offer incentives to primary users (PUs). Therefore, PUs are unwilling to cooperate with secondary users (SUs) and intend to set up stringent requirements on SUs' spectrum access. This diminishes the benefit of dynamic spectrum access and hinders its commercialization success. In this paper, we propose a novel architecture for dynamic spectrum access networks, termed incentivized cooperative dynamic spectrum access network (IC-DSAN), to motivate PUs to cooperate with SUs, such that both PUs and SUs achieve significantly higher performance. In an IC-DSAN, SU nodes serve as relays between PU nodes and while relaying PU packets, utilize network coding to encode SU packets onto PU packets, i.e., SU packets get a `free ride' via network coding. To further improve the performance, we propose a new network coding scheme termed coding over coded packets. At last, an optimization model is developed to analyze the throughput gain of IC-DSAN. The performance evaluation indicates that the throughputs of both PUs and SUs significantly increase.

Cyber Situation Awareness (CSA) often requires the collaboration among a team of cyber analysts who work at different levels and/or different parts of the system. Each team member collects data such as intrusion alerts and network logs, generates his/her own awareness for the current cyber situation, and shares the awareness with other team members to generate the comprehensive understanding of the overall situation for the purpose of team decision-making. Since each team member may have his/her own personal expertise knowledge, experience, and opinions, it is difficult for the entire team to make consensus decision when having conflicting judgments on the types of cyber attacks. Furthermore, the complexity of cyber domain significantly exacerbates the situation awareness problems for the cyber analysts. Considering that human cyber analysts tend to use ambiguous linguistics to express their own cyber situation awareness during team collaboration, we propose a fuzzy set based method that allows cyber analysts to quantify their preference and reach consensus on the cyber attack types that are most acceptable by the entire team. Also, to facilitate collaboration among team cyber analysts across distances, we present a fuzzy sets based team CSA decision-making system to demonstrate how the proposed approach provides support for generating team CSA in a distributed manner with the ability of handling uncertain information.

We introduce LOCATHE (Location-Enhanced Authenticated Key Exchange), a generic protocol that pools location, user attributes, access policy and desired services into a multi-factor authentication, allowing two peers to establish a secure, encrypted session and perform mutual authentication with pre-shared keys, passwords and other authentication factors. LOCATHE contributes to: (1) forward secrecy through ephemeral session keys; (2) security through zero-knowledge password proofs (ZKPP), such that no passwords can be learned from the exchange; (3) the ability to use not only location, but also multiple authentication factors from a user to a service; (4) providing a two-tiered privacy authentication scheme, in which a user may be authenticated either based on her attributes (hiding her unique identification), or with a full individual authentication; (5) employing the expressiveness and flexibility of Decentralized or Multi-Authority Ciphertext-Policy Attribute-Based Encryption, allowing multiple service providers to control their respective key generation and attributes., This is an extended version of 2016 International Conference on Computing, Networking and Communications (ICNC 2016), Workshop on Computing, Networking and Communications (CNC), 2016, pp. 201-205

In prior work, a CMT protocol using SCTP multihoming (termed SCTP-based CMT) was proposed and investigated for improving application throughput. SCTP-based CMT was studied in (bottleneck-independent) wired networking scenarios with ns-2 simulations. This paper studies the TCP-friendliness of CMT in the Internet. In this paper, we surveyed historical developments of the TCP-friendliness concept and argued that the original TCP-friendliness doctrine should be extended to incorporate multihoming and SCTP-based CMT. Since CMT is based on (single-homed) SCTP, we first investigated TCP-friendliness of single-homed SCTP. We discovered that although SCTP's congestion control mechanisms were intended to be ''similar'' to TCP's, being a newer protocol, SCTP specification has some of the proposed TCP enhancements already incorporated which results in SCTP performing better than TCP. Therefore, SCTP obtains larger share of the bandwidth when competing with a TCP flavor that does not have similar enhancements. We concluded that SCTP is TCP-friendly, but achieves higher throughput than TCP, due to SCTP's better loss recovery mechanisms just as TCP-SACK and TCP-Reno perform better than TCP-Tahoe. We then investigated the TCP-friendliness of CMT. Via QualNet simulations, we found out that one two-homed CMT association has similar or worse performance (for smaller number of competing TCP flows) than the aggregated performance of two independent, single-homed SCTP associations while sharing the link with other TCP connections, for the reason that a CMT flow creates a burstier data traffic than independent SCTP flows. When compared to the aggregated performance of two-independent TCP connections, one two-homed CMT obtains a higher share of the tight link bandwidth because of better loss recovery mechanisms in CMT. In addition, sharing of ACK information makes CMT more resilient to losses. Although CMT obtains higher throughput than two independent TCP flows, CMT's AIMD-based congestion control mechanism allows other TCP flows to co-exist in the network. Therefore, we concluded that CMT is TCP-friendly, similar to two TCP-Reno flows are TCP-friendly when compared to two TCP-Tahoe flows.

In dynamic spectrum access (DSA), secondary users (SUs) dynamically search and access spectrum bands unused by primary users to communicate. We propose a DSA scheme where it does not require a control channel for coordination and SU nodes do not need to exchange control messages to rendezvous. Every SU node selects its operational channel independently. When a node wants to rendezvous with another node, the former estimates the operational channel of the latter. The scheme ensures that such rendezvous has a high probability of success, while operational channels are diversified to reduce co-channel interference and hence increase throughput. We develop a mathematical model to analyze the performance of the scheme. Both analytical and simulation results show that the scheme achieves very good performance.

Constrained by the physical environments, the long-thin topology has recently been promoted for many practical deployments of wireless sensor networks (WSNs). In general, a long-thin topology is composed of a number of long branches of sensor nodes, where along a branch each sensor node has only one potential parent node toward the sink node. Although data aggregation may alleviate excessive packet contention, the maximum payload size of a packet and the dynamically changing traffic loads may severely affect the amount of sensor readings that may be collected along a long branch of sensor nodes. In addition, many practical applications of long-thin WSNs demand the exact sensor readings at each location along the deployment areas for monitoring and analysis purposes, so sensor readings may not be aggregated when they are collected. This paper proposes a lightweight, self-adaptive scheme that designates multiple collection nodes, termed lock gates, along a long-thin network to collect sensor readings sent from their respective upstream sensor nodes. The self-adaptive lock gate designation scheme balances between the responsiveness and the congestion of data collection while mitigating the funneling effect. The scheme also dynamically adapts the designation of lock gates to accommodate the time-varying sensor reading generation rates of different sensor nodes. A testbed of 100 Jennic sensor nodes is developed to demonstrate the effectiveness of the proposed lock gate designation scheme. Copyright © 2011 John Wiley & Sons, Ltd.

Cooperative communications fundamentally changes the abstraction of a wireless link and offers significant potential advantages for wireless networks. However, such technologies are evaluated with idealized scenarios where many control costs are assumed to be negligible. Moreover, even if these costs appear small in simple network scenarios, they increase significantly with the size and traffic level of the network, requiring careful evaluation, or even innovative design, of cooperative protocols to ensure their usefulness in realistic networks. This article describes a realistic evaluation of cooperative communications in a networking context. Insights obtained from this evaluation help guide work on cooperative communications toward practical and potentially beneficial protocols.

With the rapid development of wireless technologies, the future generation wireless networks have more challenges for providing reliable and high quality end-to-end performance in wireless multimedia communications. A cross-layer design has become a popular topic in which more and more researchers are engaged. That leads to a lot of cross-layer design proposals for wireless networks. This special issue aims to collect and foster stateof-the-art research pertaining to cross-layer design in the area of future generation wireless networks. The emphasis of this special issue will be on cross-layer protocol interactions and design of cross-layer optimized techniques. The accepted fourteen papers are grouped into six main themes. The first set of papers deals with the cross-layer energy-efficient and power control mechanisms. The second set reports the cross-layer routing protocols. The third set of papers investigates theTCP improvement schemes using cross-layer design. The fourth set of papers describes the cross-layer multimedia schemes. The fifth set of papers displays the cross-layerQoS scheduling schemes. The final set of papers discusses the cross-layer design in IEEE 802.16 networks. In the first set of papers, the cross-layer energy-efficient design and power control mechanisms are reported. In the first paper, Li-Chun Wang, Jane-Hwa Huang, Anderson Chen, and Chung-Ju Chang, proposed the cross-layer analysis of joint rate and power adaptation in Nakagami fading channels with multiple-user contention. The authors proposed channeldriven rate and power adaptation (CDRPA) schemes and develop a physical (PHY)/medium

Today's static spectrum allocation policy results in a situation where the available spectrum is being exhausted while many licensed spectrum bands are under-utilized. To resolve the spectrum exhaustion problem, the cognitive radio wireless network, termed CogNet in this paper, has recently been proposed to enable unlicensed users to dynamically access the licensed spectrum bands that are unused in either temporal or spatial domain, through spectrum-agile cognitive radios. The CogNet plays the role of secondary user in this shared spectrum access framework, and the spectrum bands accessible by CogNets are inherently heterogeneous and dynamic. To establish the communication infrastructure for a CogNet, the cognitive radio of each CogNet node detects the accessible spectrum bands and chooses one as its operating frequency, a process termed channel assignment. In this paper we propose a graph-based path-centric channel assignment framework to model multi-hop ad hoc CogNets and perform channel assignment from a network perspective. Simulation results show that the path-centric channel assignment framework outperforms traditional link-centric approach.

The minimum-energy multicast tree problem aims to construct a multicast tree rooted at the source node and spanning all the destination nodes such that the sum of transmission power at non-leaf nodes is minimized. However, aggressive power assignment at non-leaf nodes, although conserving more energy, results in multicast trees that suffer from higher hop count and jeopardizes delay-sensitive applications, signifying a clear tradeoff between energy efficiency and delay. This article formulates these issues as a constrained Steiner tree problem, and describes a distributed constrained Steiner tree algorithm, which jointly conserves energy and bounds delay for multicast routing in ad hoc networks. In particular, the proposed algorithm concurrently constructs a constrained Steiner tree, performs transmission power assignment at non-leaf nodes, and strives to minimize the sum of transmission power of non-leaf nodes, subject to the given maximum hop count constraint. Simulation results validate the effectiveness and reveal the characteristics of the proposed algorithm.

Time indexed information refers to information whose instance producing time is used as the search key for its access. One common scenario of querying time indexed information is to discover the information instance whose producing time is the closest to a given queried time. However, in the context of mobile ad hoc networks (MANETs), lack of infrastructure support, node mobility, and potential packet loss in wireless communications make querying time indexed information a challenging task. This paper describes a Self-Organizing Mechanism for querying Time indexed Information in MANETs, termed SOMTI. Using SOMTI, each instance producer h discovers routes to a set of instance producers whose instance producing times are the closest to a set of computed time points both before and after h's instance producing time. These routes form a web of search indices, which allow queries received by any instance producer to be forwarded in the manner of n-ary search for the instance producer whose instance producing time is the closest to the queried time. Both mathematical analysis and simulation study show that SOMTI is scalable with the number of nodes and the query producing rate. In addition, simulations results demonstrate that the goodness, in terms of the closeness to the queried time, of the discovered instance is always better than competing approaches under various node mobility speeds, query generation rates, and the number of nodes in the network, which demonstrates the effectiveness of SOMTI.

This paper addresses the issue of improving multicast packet delivery in mobile ad hoc networks and proposes an adaptive mechanism called Protocol-Independent Packet Delivery Improvement Service (PIDIS) to recover lost multicast packets. PIDIS provides its packet-delivery improvement services to any multicast routing protocol for mobile ad hoc networks by exploiting the mechanism of swarm intelligence to make intelligent decisions about where to fetch the lost multicast packets from. PIDIS is a gossip protocol, and nodes using PIDIS are only concerned with which neighbor nodes to gossip with to recover the most lost packets, rather than which member nodes to gossip with. Thus, it does not rely on membership information in a multicast scenario, which is often difficult to get. PIDIS employs the beneficial aspects of probabilistic routing and adapts well to mobility. PIDIS achieves probabilistic improvement in multicast packet delivery and, unlike other gossip-based schemes, does not need to maintain information about group members from which lost multicast packets are retrieved. Further, the operations of PIDIS do not rely on any underlying routing protocol or primitive, and can be incorporated into any ad hoc multicast routing protocol. We incorporated PIDIS over ODMRP [On-Demand Multicast Routing Protocol in Multihop Wireless Mobile Networks, Kluwer Mobile Networks and Applications, 2000], and compared it against Anonymous Gossip (AG) [International Conference on Distributed Computing Systems (ICDCS 2001) Phoenix, Arizona, April 2001] implemented over ODMRP, and ODMRP itself. Our simulation results show that ODMRP+PIDIS is more efficient and performs better than ODMRP+AG and ODMRP in terms of multicast packet delivery, end-to-end delay, and MAC layer overheads. We attribute the better performance and lower MAC overheads of ODMRP+PIDIS to the efficient gossiping made possible by using the swarm intelligence techniques.

In-band full-duplex (IBFD) radios can double the spectral efficiency in theory, and their feasibility has been demonstrated by using advanced cancellation methods for terrestrial communications. We investigate the feasibility of acoustic IBFD in the underwater acoustic (UWA) channel, to enhance the spectral efficiency in the severely bandwidth-limited aquatic environment. We discuss the challenges of implementing IBFD UWA systems. Further, we propose an acoustic-specific cancellation scheme to deal with the strong multipath self-interference in IBFD UWA systems. We show, through simulations, that the proposed scheme can effectively suppress different types of interference.

End-to-end latency is critical to many distributed applications and services that are based on computer networks. There has been a dramatic push to adopt wireless networking technologies and protocols (such as WiFi, ZigBee, WirelessHART, Bluetooth, ISA100.11a, etc.) into time-critical applications. Examples of such applications include industrial automation, telecommunications, power utility, and financial services. While performance measurement of wired networks has been extensively studied, measuring and quantifying the performance of wireless networks face new challenges and demand different approaches and techniques. In this paper, we describe our work in progress of designing a measurement platform based on the technologies of software-defined radio (SDR) and IEEE 1588 Precision Time Protocol (PTP) for evaluating the performance of wireless networks.

This work presents an application of the highly expressive Attribute-Based Encryption to implement Secure Zones for firearms. Within these zones, radio-transmitted local policies based on attributes of the user and the firearm are received by embedded hardware in the firearms, which then advises the user about safe operations. The Secure Zones utilize Attribute-Based Encryption to encode the policies and user attributes, and providing privacy and security through it cryptography. We describe a holistic approach to evolving the firearm to a cyber-physical system to aid in augmenting safety. We introduce a conceptual model for a firearm equipped with sensors and a context-aware software agent. Based on the information from the sensors, the agent can access the context and inform the user of potential unsafe operations. To support Secure Zones and the cyber-physical firearm model, we propose a Key Infrastructure Scheme for key generation, distribution, and management, and a Context-Aware Software Agent Framework for Firearms., Communications and Network Security (CNS), 2013 IEEE Conference on. arXiv admin note: substantial text overlap with arXiv:1411.1733

In wireless networks such as those based on IEEE 802.11, packet losses due to fading and interference are often misinterpreted as indications of congestion, causing unnecessary decrease in the data sending rate due to congestion control at higher layer protocols. For delay-constrained applications such as video teleconferencing, packet losses may result in excessive artifacts or freeze in the decoded video. We propose a simple and yet effective mechanism to detect and reduce channel-caused packet losses by adjusting the retry limit parameter of the IEEE 802.11 protocol. Since retry limit is left configurable in the IEEE 802.11 standard, and does not require cross-layer coordination, our scheme can be easily implemented and incrementally deployed. Experimental results of applying the proposed scheme to a WebRTC-based realtime video communication prototype show significant performance gain compared to the case where retry limit is configured statically.

Dynamic Adaptive Streaming over HTTP (DASH) is being adopted as a cost effective means for multimedia delivery. User Adaptive Video (UAV) is a new technique that exploits the perceptual limits of the human visual system to modulate a video stream's bit rate based on the viewing conditions, such as viewing distance and ambient illuminance, resulting in significant bandwidth reduction without perceived loss of quality to the user. UAV presents an opportunity to significantly improve the efficiency of DASH by not requesting unnecessarily high bit rate video. Due to the random access nature of the Wi-Fi MAC protocol and the intricate interaction among DASH traffic flows, it is not clear whether UAV will manifest its benefits in Wi-Fi networks. We design UAV-enabled DASH (UDASH) and evaluate its performance in Wi-Fi networks. We show that UDASH in a Wi-Fi network has the benefits of not only improving the video streaming performance such as reducing the rebuffering probability, but also enhancing the performance of cross traffic. We also give the conditions under which the benefits can be achieved. Simulation results confirm that the benefits of UDASH are significant.

As the market for cellular telephones, and other mobile devices, keeps growing, the demand for new services arises to attract the end users. Location Based Services (LBS) are becoming important to the success and attractiveness of next generation wireless systems. To access location-based services, mobile users have to disclose their location information to service providers and third party applications. This raises privacy concerns, which have hampered the widespread use of LBS. Location privacy mechanisms include Anonymization, Obfuscation, Policy Based Scheme, k-anonymity and Adding Fake Events. However most existing solutions adopt the k-anonymity principle. We propose an entropy based location privacy mechanism to protect user information against attackers. We look at the effectiveness of the technique in a continuous LBS scenarios, i.e., where users are moving and recurrently requesting for Location Based Services, we also evaluate the overall performance of the system with its drawbacks.

This work presents a mobile sign-on scheme, which utilizes Bluetooth Low Energy beacons for location awareness and Attribute-Based Encryption for expressive, broadcast-style key exchange. Bluetooth Low Energy beacons broadcast encrypted messages with encoded access policies. Within range of the beacons, a user with appropriate attributes is able to decrypt the broadcast message and obtain parameters that allow the user to perform a short or simplified login. The effect is a "traveling" sign-on that accompanies the user throughout different locations., Comment: Communications and Network Security (CNS), 2013 IEEE Conference on. arXiv admin note: text overlap with arXiv:1410.0983

Cyber attacks have been increasing significantly in both number and complexity, prompting the need for better training of cyber defense analysts. To conduct effective training for cyber situation awareness, it becomes essential to design realistic training scenarios. In this paper, we present a Cognitive Task Analysis based approach to address this training need. The technique of Cognitive Task Analysis is to capture and represent knowledge used by experts to perform complex tasks. Accurate characterization of cyber security experts’ cognitive processes can be incorporated into training materials to teach novice cyber analysts how to think and act like experts. After performing Cognitive Task Analysis of cyber situation awareness, we identify the steps necessary for designing training scenarios and training workflows. In order to address the challenge of information overload confronting the cyber analysts, we identify and design attack-specific watch list items. During training, cyber analysts can tailor their own watch list items and triggering thresholds in order to detect cyber attacks faster. As the time it takes for cyber analysts to recognize, analyze, and respond to attacks is critical, we evaluate cyber analysts’ performance based on their response time compared with the ideal attack timeline.

We present a hybrid routing protocol for both pure and hybrid ad hoc networks which uses the mechanisms of swarm intelligence to select next hops. Our protocol, Ad hoc Networking with Swarm Intelligence (ANSI), is a congestion-aware routing protocol, which, owing to the self-organizing mechanisms of swarm intelligence, is able to collect more information about the local network and make more effective routing decisions than traditional MANET protocols. Once routes are found, ANSI maintains routes along a path from source to destination effectively by using swarm intelligence techniques, and is able to gauge the slow deterioration of a link and restore a path along newer links as and when necessary. ANSI is thus more responsive to topological fluctuations. ANSI is designed to work over hybrid ad hoc networks: ad hoc networks which consist of both lower-capability, mobile wireless devices and higher-capability, wireless devices which may or may not be mobile. In addition, ANSI works with multiple interfaces and with both wired and wireless interfaces.Our simulation study compared ANSI with AODV on both hybrid and pure ad hoc network scenarios using both TCP and UDP data flows. The results show that ANSI is able to achieve better results (in terms of packet delivery, number of packets sent, end-to-end delay, and jitter) as compared to AODV in most simulation scenarios. In addition, ANSI achieves this performance with fewer route errors as compared to AODV. Lastly, ANSI is able to perform more consistently, considering the lower variation (measured as the width of the confidence intervals) of the observed values in the results of the experiments. We show that ANSI's performance is aided by both its superior handling of routing information and also its congestion awareness properties, though we see that congestion awareness in ANSI comes at a price.

This paper proposes a new approach that applies multibeam directional antennas to controlling topology by reducing the power intensity directionally instead of omnidirectionally. In contrast to omnidirectional topology control, which reduces transmission power (and, thus, the resulting transmission range) in all directions, the proposed approach maintains the original power range in certain directions while clearing the power intensity in other directions. This paper shows that the proposed approach and the. omnidirectional topology control approach are equivalent in terms of the probability distribution of the number of symmetric neighbors in their resulting topologies. Major benefits of this approach include reduced and steady hop count, power saving independent of the number of neighbors within the original power range, and symmetric link in terms of SNR quality, as compared to omnidirectional topology control approaches. Simulation studies have demonstrated these benefits and highlighted its trade-offs.

For mobile ad hoc networks, network-wide broadcast is a critical network layer function supporting route discovery and maintenance in many unicast and multicast protocols. A number of broadcast schemes have been proposed; however, almost all of them assume the usage of omnidirectional antennas and focus on broadcast overhead in terms of the number of forwarding nodes. Directional antennas have narrow beams and can potentially reduce broadcast overhead in terms of the ratio of the number of received duplicate packets to the number of nodes that receive broadcast packets. In this paper, we propose to map probability-based directional and omnidirectional broadcast to bond and site percolation, respectively, and describe a collection of directional antenna-based broadcast schemes for mobile ad hoc networks. A thorough and comparative simulation study is conducted to demonstrate the efficiency of the proposed schemes.

Small-cell networks have been proposed to meet the demand of ever growing mobile data traffic. One of the prominent challenges faced by small-cell networks is the lack of sufficient backhaul capacity to connect small-cell base stations (small-BSs) to the core network. We exploit the effective application layer semantics of both spatial and temporal locality to reduce the backhaul traffic. Specifically, small-BSs are equipped with storage facility to cache contents requested by users. As the {\em cache hit ratio} increases, most of the users' requests can be satisfied locally without incurring traffic over the backhaul. To make informed caching decisions, the mobility patterns of users must be carefully considered as users might frequently migrate from one small cell to another. We study the issue of mobility-aware content caching, which is formulated into an optimization problem with the objective to maximize the caching utility. As the problem is NP-complete, we develop a polynomial-time heuristic solution termed {\em MobiCacher} with bounded approximation ratio. We also conduct trace-based simulations to evaluate the performance of {\em MobiCacher}, which show that {\em MobiCacher} yields better caching utility than existing solutions., Accepted by Globecom 2014

By adjusting the transmission power of mobile nodes, topology control aims to reduce wireless interference, reduce energy consumption, and increase effective network capacity, subject to connectivity constraints. In this paper, we introduce the Ant-Based Topology Control (ABTC) algorithm that adapts the biological metaphor of Swarm Intelligence to control topology of mobile ad hoc networks. ABTC is a distributed algorithm where each node asynchronously collects local information from nearby nodes, via sending and receiving ant packets, to determine its appropriate transmission power. The operations of ABTC do not require any geographical location, angle-of-arrival, topology, or routing information, and are scalable. In particular, ABTC attempts to minimize the maximum power used by any node in the network, or minimize the total power used by all of the nodes in the network. By adapting swarm intelligence as an adaptive search mechanism, ABTC converges quickly to a good power assignment with respect to minimization objectives, and adapts well to mobility. In addition, ABTC may achieve common power, or properly assign power to nodes with non-uniform distribution. Results from a thorough comparative simulation study demonstrate the effectiveness of ABTC for different mobility speed, various density, and diverse node distributions.

Swarm intelligence refers to complex behaviors that arise from very simple individual behaviors and interactions, which is often observed in nature, especially among social insects such as ants. Although each individual (an ant) has little intelligence and simply follows basic rules using local information obtained from the environment, such as ant's pheromone trail laying and following behavior, globally optimized behaviors, such as finding a shortest path, emerge when they work collectively as a group. In this paper, we apply this biologically inspired metaphor to the multicast routing problem in mobile ad hoc networks. Our proposed multicast protocol adapts a core-based approach which establishes multicast connectivity among members through a designated node (core). An initial multicast connection can be rapidly setup by having the core flood the network with an announcement so that nodes on the reverse paths to the core will be requested by group members to serve as forwarding nodes. In addition, each member who is not the core periodically deploys a small packet that behaves like an ant to opportunistically explore different paths to the core. This exploration mechanism enables the protocol to discover new forwarding nodes that yield lower total forwarding costs, where cost is abstract and can be used to represent any metric to suit the application. Simulations have been conducted to demonstrate the performance of the proposed approach and to compare it with certain existing multicast protocols.

Future space missions are envisioned to be implemented using a flexible, distributed architecture consisting of constellations of dynamically deployed or configured space and mobile platforms that are networked together into an integrated information system, which we term an ad hoc space network. An ad hoc space network is characterized by changing topology and potentially sparse and intermittent connectivity, which pose unique challenges to routing. In this paper we describe a flexible routing architecture for ad hoc space networks, consisting of an interrogation-based relay routing mechanism and an attribute-based naming (AN) and intentional routing (IR) scheme. The interrogation-based relay routing mechanism allows satellites to buffer data and to interrogate each other so as to make intelligent routing decisions. The AN and IR scheme facilitate mission-specific routing capability. We present a simulation study of the effects of buffer space, satellite density, and orbital patterns on the throughput of the interrogation-based relay routing mechanism.

The topology of an ad hoc network has a significant impact on its performance in that a dense topology may induce high interference and low capacity, while a sparse topology is vulnerable to link failure and network partitioning. Topology control aims to maintain a topology that optimizes network performance while minimizing energy consumption. Existing topology control algorithms utilize either a purely centralized or a purely distributed approach. A centralized approach, although able to achieve strong connectivity (k-connectivity for k /spl ges/ 2), suffers from scalability problems. In contrast, a distributed approach, although scalable, lacks strong connectivity guarantees. We propose a hybrid topology control framework, cluster-based topology control (CLTC) that achieves both scalability and strong connectivity. By varying the algorithms utilized in each of the three phases of the framework, a variety of optimization objectives and topological properties can be achieved. In this paper, we present the CLTC framework; describe topology control algorithms based on CLTC and prove that k-connectivity is achieved using those algorithms; analyze the message complexity of an implementation of CLTC, namely, CLTC-A, and present simulation studies that evaluate the effectiveness of CLTC-A for a range of networks.

Traditional user authentication involves entering a username and password into a system. Strong authentication security demands, among other requirements, long, frequently hard-to-remember passwords. Two-factor authentication aids in the security, even though, as a side effect, might worsen user experience. We depict a mobile sign-on scheme that benefits from the dynamic relationship between a user's attributes, the service the user wishes to utilize, and location (where the user is, and what services are available there) as an authentication factor. We demonstrate our scheme employing Bluetooth Low Energy beacons for location awareness and the expressiveness of Attribute-Based Encryption to capture and leverage the described relationship. Bluetooth Low Energy beacons broadcast encrypted messages with encoded access policies. Within range of the beacons, a user with appropriate attributes is able to decrypt the broadcast message and obtain parameters that allow the user to perform a short or simplified login., Comment: Accepted at International Conference on Computing, Networking and Communications (ICNC 2015)

This article introduces a sensor information networking architecture, called SINA, that facilitates querying, monitoring, and tasking of sensor networks. SINA serves the role of middleware that abstracts a network of sensor nodes as a collection of massively distributed objects. SINA's execution environment provides a set of configuration and communication primitives that enable scalable and energy-efficient organization of and interactions among sensor objects. On top the execution environment is a programmable substrate that provides mechanisms to create associations and coordinate activities among sensor nodes. Users then access information within a sensor network using declarative queries, or perform tasks using programming script.

Existing software development environments for discrete-event simulation have adopted either a language-based or a library-based approach. Although these approaches have advantages, they suffer from three limitations: lack of portability, lack of interoperability, and difficulty in execution over the Internet/Web infrastructure. The paper addresses these limitations by proposing to facilitate discrete-event simulation as a service on the Internet/Web. The simulation service is defined as a corba facility with a well-defined interface, and components of simulation applications access the facility to obtain execution support. The simulation facility enables portability and interoperability of simulation applications which may be developed in heterogeneous languages and environments and communicate over the Internet. Moreover, by integrating with Java, the approach also enables simulation applications to be developed in Java and executed on the Web. Application of the simulation facility is illustrated by using a bounded-buffer producer/consumer system.

This letter extends and improves prior unicast transport capacity results for the general multi-channel, multi- radio, multi-hop wireless networks, where channels may have different data rates, and the number of interfaces per node may differ from the number of channels available in the network. Both the upper bound and the lower bound are rigorously derived for the Arbitrary Networks with interference modeled by the protocol model. Also presented is a minor but important improved use of the protocol model in the derivation of the transport capacity upper bound.

This paper describes the connection management research done by the Network Control and Management (NC&M) task force under the multiwavelength optical networking (MONET) program. MONET is sponsored by the Defense Advanced Research Project Agency (DARPA) the US Government Department of Defense, with participation from Bellcore, AT&T, Lucent Technologies, several government agencies, and regional Bell operating companies. MONET's vision is to develop a flexible reliable high-capacity high-performance cost-effective national optical network based on multiwavelength fiber optic technology. As an important component in realizing this vision, the MONET program includes the architecture and design of a prototype network control and management system for MONET's reconfigurable wavelength-division multiplexing (WDM) all-optical network. The primary objectives of the prototype research work are to develop the architecture and framework for managing national-scale transparent reconfigurable WDM optical networks and to demonstrate the feasibility of the NC&M prototype system in a field experiment network in Washington, DC. This prototype system allows the program participants to conduct experiments and gain experience in the management and operations of reconfigurable optical networks. This paper describes the connection management aspects of the prototype system, addressing issues such as the management architecture, information model, and provisioning algorithms of the prototype management system.

Heterogeneous wireless networks have been widely studied recently for the potential to accommodate the rapidly growing data demand in wireless networks. In addition to achieving a higher data rate, power efficient transmission is also critical in providing a stable and lasting wireless access. In this work, we study the power efficient user pairing for multicasting in heterogeneous wireless networks. A combination of intelligent cell association and cooperative communications is proposed to minimize the maximum power consumption among the mobile users. Through analysis and simulation, we demonstrate the benefits of efficient cell association as well as the incorporation of cooperative communications. It shows that our proposed power efficient user pairing scheme achieves a near-optimal performance with a low complexity.

In previous work, we introduced a novel swarming interpolation framework and validated its effectiveness on static fields. In this paper, we show that a slightly revised version of this framework is able to track fields that translate, rotate, or expand over time, enabling interpolation of both static and dynamic fields. Our framework can be used to control autonomous mobile sensors into flexible spatial arrangements in order to interpolate values of a field in an unknown region. The key advantage to this framework is that the stable sensor distribution can be chosen to resemble a Chebyshev distribution, which can be optimal for certain ideal geometries.

In this paper, we analyze general models of large swarms with covert leaders. A covert leader is an individual who acts on additional information but is treated like all other individuals in the swarm. We concentrate our efforts on behavior driven by three-zone swarming, and present a new nonlinear model in which a leader will respond more strongly to additional information when the swarm is less dense. Conversely, leaders in denser regions behave more like followers. Linear stability analysis shows that the growth or decay of perturbations in an infinite, uniform swarm depends on the strength of attraction relative to repulsion and orientation. Understanding general systems like this has a wide range of applications in ecology, sociology and wireless robotics.

The Advanced Technology Demonstration Network (ATDNet) is a major testbed facility established by DARPA and other U.S. government agencies to conduct network and applications research on the next generation of high speed ATM/SONET networks. This article presents the approaches and results of our work in network management on ATDNet. The research addresses different aspects of next-generation systems design, including integrated network management of different technology layers, multitier and multiprotocol architectures, robust distributed computing platforms, and object-oriented technologies. To address these challenges in a practical manner, the authors describe their implementation of a prototype software system developed on a distributed computing platform, discuss how this research addresses the current and evolving needs of ATDNet, and present possible future research directions.

In this paper, we analyze and evaluate swarm interactions using varying amounts of kinetic memory, defined as the stored velocity states for n discrete time steps in the past. We show that kinetic memory can play a key role in the dynamics of biological and artificial aggregations. It is reasonable to suppose that individuals possess a memory of the immediate past and use this information to their advantage when swarming. Similarly, in wireless robotic applications, the storage of past movements requires nocommunication and can be used to stabilize aggregations. In fact, in wireless robotic applications, the communication rate between nearby individuals is more limited than in many biological applications, so the time step used to update an individual's velocity is greater. In this paper, we develop and analyze updating schemes for interacting individuals in a swarm. We show that we can stabilize and destabilize coherent translating structures using suitable adjustments to the updating scheme. Using this framework, we design an updating scheme to provide maximum stability for coherent structures that arise from a three-zone swarming model. Finally, we verify the effectiveness of our updating methodology using realistic QualNet simulations of a swarm of networked robots.