waashk/dblp huggingface dataset:
replica arrangement scheme for location dependent information on sensor networks with unpredictable query frequency. storing data on sensor nodes at a specified location is a useful technique for data-centric storage and management of location dependent data on wireless sensor networks. to decrease the cost of accessing these data, arranging replicas of data so that the distance between the consumer nodes and replica holder nodes decreases is desirable. conventional schemes, however, are costly for updating the replicas even if they are not often used or do not support functions for ensuring their consistency. we propose a novel replica arrangement scheme, which adaptively arranges replicas at positions close to nodes for frequent sending of queries. instead of arranging many replicas on sensor nodes, our scheme consists of nodes with pointers that point to the replica holder nodes in order to save storage for replicas. the pointers, which are smaller than replicas, are arranged so that nodes are in circular arcs surrounding the location where the original data item is associated. simulation results show that our scheme outperforms conventional replica arrangement schemes in terms of the cost required for sending queries and replies with sufficiently low replica update cost.
a new efficient mechanism for establishing ip connectivity between ambient networks. the changes in the communication paradigm envisioned for future networks, with peer-to-peer/symmetric attachments gaining momentum and two ip (internet protocol) versions coexisting, will pose new challenges to mobile communication networks. traditional ip autoconfiguration mechanisms will not work properly, since they were designed mostly having in mind a client-server/asymmetric attachment model, they assume a single ip version paradigm, and they target the auto-configuration of devices only. the ist ambient networks project has introduced a new concept - the ambient network - that enables handling every communication entity, either a single device or an entire network, as an ambient network (an). this paper describes a new efficient mechanism, named basic connectivity (bc) mechanism, for autoconfiguring ip connectivity between attaching ans. a proof-of-concept prototype, experimental results, and theoretical analysis show that bc suites the future networking paradigm and represents a solution more efficient than the current trial-and-error mechanism for auto-configuring ip connectivity.
an approach for increasing base-station anonymity in sensor networks. wireless sensor networks (wsn) are becoming an attractive choice for many critical applications, such as border protection and combat field reconnaissance. in these applications, sensors probe their surroundings and send their findings to a base-station (bs) over multi-hop paths. given the important role of the bs, an adversary who likes to disrupt the network operation would eagerly look for where the bs could be and target it with attacks in order to inflict maximum damage. the continuous flow of traffic towards the bs creates a pronounced pattern of wireless links that may expose the bs position and thus make the network more vulnerable. this paper investigates means for boosting the anonymity of the bs. first, we adapt three models -entropy based model, gsat test and evidence theory model, to quantify anonymity in the context of wsn. we further customize models that conventionally measure anonymity of the entire network, to suit the bs. then, a novel approach for boosting the anonymity of the bs is proposed. the idea is for the bs to disguise itself by transmitting some of the data packets it receives with varying intensity. the goal is to create a perception that the bs node is just another sensor node sending data and thus confuse the adversary. the approach is validated through simulation.
modeling of a public safety communication system for emergency response. this paper describes simulation work in modeling a city-wide trunked radio system and evaluating its performance under stress. specifically, traffic models are developed to simulate both routine background traffic and the traffic load associated with an emergency scenario of a high-rise apartment fire. an analysis of a one-month radio data log provided insights on the traffic distribution among different talkgroups, as well as building individual traffic loading profiles for the talkgroups directly involved in the emergency response. the performance of the radio system is evaluated under different traffic loading intensity levels. initial simulation results show that this emergency response communication system provides adequate capacity even under intense traffic loading. however, one area of concern is the build-up of waiting calls within some heavily loaded talkgroup, which results in long waiting time to access the channel.
nash bargaining over mimo interference systems. in this paper, the source covariance matrices of multiple-input multiple-output (mimo) interference channels (ifcs) are investigated from a game-theoretic perspective. it is proved that the requirement of sufficiently small interference-to-noise ratio (inr) is the sufficient condition for the uniqueness of the nash bargaining (nb) solution. the structure of the source covariance matrices, which constitute the feasible set of nb solution, is analyzed by comparing them with the covariance matrices leading to the nash equilibrium (ne). the existence of the nb solution and concavity of the rate product for mimo ifcs are also studied.
constellation rotated vector ofdm and its performance over rayleigh fading channels. although the single antenna vector ofdm (vofdm) proposed by xia is robust to channel spectral nulls, it does not necessarily attain full diversity for multi-path fading channels. in this paper, we propose a novel constellation-rotated v-ofdm (crv-ofdm) system based on modified v-ofdm, and analyze its performance over rayleigh fading channels. in crv-ofdm, we design rotation angles for each symbol to minimize upper bounds on bit error rate (ber) with full diversity order. our simulation results show that, compared with v-ofdm, proposed crv-ofdm always attains the maximum diversity order determined by the vector length m. as a result, for ber 10-4, crv-ofdm improves the performance of v-ofdm by 2db for both bpsk and qpsk modulation for m = 2, and, for m = 4, the improvement is about 1.3db. to verify optimality of the derived angles, we also test, in therms of ber, some other angles including the angles derived from minimum product distance (mpd) criterion and compare with the theoretical union bounds and show that the bers take the smallest values at our derived optimal angles.
a distributed protocol for virtual device composition in mobile ad hoc networks. the dynamic composition of systems of networked appliances, or virtual devices, in manets, enables users to generate, on-the-fly, complex strong specific systems. current work in the development of service composition architectures in manets has yet to address qos metrics for enhanced composition from a virtual device perspective. in this paper, we present an extension to a prominent dynamic broker-based distributed service composition protocol, embedding in a distributed manner, a qos model providing compositions that form the best possible virtual device at the time of need. simulation results show that our protocol extension provides a high increase in qos at a low cost in terms of increased amounts of messages and composition time.
identifying the use of data/voice/video-based p2p traffic by dns-query behavior. there are more and more p2p applications in the internet, with or without encrypted content. the p2p applications can be classified into three categories: file sharing (bt, emule), voip (skype, msn), and video streaming (ppstream, pplive). by observing the common communication nature among the peers, this paper proposes a simple but efficient way to identify the p2p traffic by the dns query behavior. experimental results illustrate that the proposed mechanism is able to accurately identify if a host is using data/voice/video-based p2p traffic, even the packet content is encrypted. the proposed mechanism is also capable of detecting future unknown p2p applications as long as they perform the common p2p behaviors.
joint message-passing symbol-decoding of ldpc coded signals over partial-response channels. we consider the problem of joint detection and decoding of low-density parity-check (ldpc) coded signals over partial response (pr) channels. a method to graphically represent the constraints imposed by the channel and the code on the channel output sequence is introduced. this enables the design of a detector and decoder that estimates a posteriori probabilities of noiseless channel output symbols rather than binary channel inputs. by running the sum-product algorithm (spa) on this graph, a joint decoder is obtained that is shown to perform significantly better than the turbo-equalizer, at the cost of increased computational complexity.
throughput enhancement in multi-carrier systems employing overlapping weyl-heisenberg frames. a methodology for doubling the throughput of multi-carrier systems is proposed. throughput enhancement method is introduced by using pulse shaping in multi-carrier systems. by employing more than one weyl- heisenberg frames that are orthonormal both within the frame and in between the frames, the throughput of multi-carrier systems is increased. different lattice density scenarios are investigated for throughput enhancement. it is shown that by employing the proposed methodology, throughput of a multi-carrier system can be doubled. theoretical analysis quantifying throughput enhancements are presented and results are supported by simulation studies. a system level comparison is presented for ieee 802.16 standards. the effects of various impairments are investigated.
efficient sample rate conversion in software radio employing folding number system. in an ideal software radio, digitization of the received signal occurs immediately after receive antenna to enable channelization to be performed in the discrete time domain. however, this vision is still far from reality due to limitations of current analog to digital converter performance. in this paper, a novel number system called the folding number system (fns) is proposed for use in software radio. we implement sample rate conversion immediately after the receive antenna using this number system thus providing an efficient solution to the above problem. by decomposing the input analog signal into separate channels in parallel, symmetrical residues are obtained with reduced number of comparators. these residues together with the folding information are processed in parallel in the fns domain. the fns has the same computational complexity as that in residue number system but the need for the intermediate steps such conversion of the analog data into binary and subsequently into residues is absent.
fpga implementation of rls adaptive filter using dichotomous coordinate descent iterations. in this paper, we present an fpga implementation of a recursive least squares adaptive filtering algorithm based on dichotomous coordinate descent iterations. the algorithm is simple for finite precision implementation, requires small chip resources, and exhibits numerical stability. for arbitrary regressors (as in antenna array beamforming), the proposed implementation allows significant increase in the weight update rate compared to implementations based on qr decomposition; for 9 and 32-element arrays, the update rates are as high as 162 khz and 31 khz, respectively. for 16-tap and 64-tap transversal filters, the proposed implementation provides the weight update rate 207 khz and 76 khz, respectively.
a performance analysis on route optimization for proxy mobile ipv6. proxy mobile ipv6 has been developed from the concept of network-based mobility support protocol in the ietf. the recently published specification of proxy mobile ipv6 only focuses on the mobility support. then, route optimization issues are left in the basket for further works. in this paper, we provide the performance analysis in where the recently proposed route optimization is evaluated in terms of signaling cost and packet delivery cost. through the provided analysis results, we demonstrate that route optimization solves the ineffective routing path problem during the mobile host communicates with its corresponding host and argue that the scalability of proxy mobile ipv6 architecture is improved due to the distributed routing path. in addition, the cost model developed in this paper would be a reference model in order to facilitate decision-making for further route optimization design.
detecting greedy behaviors by linear regression in wireless ad hoc networks. the csma/ca protocol is well known to handle the channel access to various users in wireless ad hoc networks using ieee 802.11 technology. this protocol requires nodes to wait for some time before initiating a transmission to avoid collisions. as a result, the greedy behavior of some misbehaving nodes can try to lower their waiting time in order to access the channel earlier and penalize the other nodes. in order to avoid this misbehavior, we propose in this paper a model based on measuring the linear regression of nodes' access time to the channel. we have demonstrated that this model exhibits a linear regression between the different nodes' access time. this result has been also confirmed by simulations. in this model, each deviation from the estimated slope is considered as a source of cheating from a corresponding node. by using this detection model, we were able to detect most of the misbehaving nodes in wireless ad hoc networks without requiring modifications to the ieee 802.11 mac protocol.
a handover scheme based on moving extended cells for 60 ghz radio-over-fiber networks. we demonstrate a handover scheme for supporting high end-user mobility in a 60 ghz broadband picocellular radio-over-fiber network. the proposed scheme relies on a novel moving extended cell (mec) concept which is based on user-centric virtual groups of adjacent cells that transmit the same data content to the user. the mec concept utilizes a mechanism for restructuring the virtual multi-cell area according to the user's mobility pattern, so that a virtual antenna group moves together with the mobile user. a mathematical model is developed and performance evaluation is also conducted and presented, demonstrating zero packet loss and call dropping probability values in high-rate wireless services for a broad range of mobile speeds up to 40m/sec and independently of the fiber link distances.
epson: enhanced physical security in ofdm networks. secure wireless communications is a challenging problem due to the shared nature of the wireless medium. most existing security mechanisms focus on traditional cryptographic schemes. in recent years, features of the multi-path channel (such as randomness and reciprocity), have driven researchers to exploit its potential to enhance the security of wireless networks. as ofdm occupies wide bandwidth, it will experience a prolific source of multi-path components. in this paper, we comprehensively exploit the inherent physical parameters of the multi-path fading channel to achieve continuous two way authentication between wireless terminals. in our scheme, pilot information is randomly spread in a wideband channel, leading to low probability of detection (lpd). unlike other channel-based approaches, the information of both amplitude and phase in the channel signature is fully utilized to enhance the security of the ofdm communication network. more specially, the receiver will detect the channel response continuously according to the randomly inserted pilots and identify the valid user based on the statistical channel signature information. simulation results indicate the high efficiency of the proposed method.
a case study for evaluating ieee 802.15.4 wireless sensor network formation with mobile sinks. wireless sensor networks are traditionally composed of a multiplicity of sensor nodes that sense given phenomena and deliver the sensed data to specific sink nodes. in the most of the application scenarios, sensor nodes have been considered motionless. on the contrary, interesting possibilities arise if some sensors are embedded in devices carried by mobile agents as people, cars, animals, etc. if sinks move within the considered sensor field, they are able to provide both sparse sensing and collecting of data measured by static sensors placed at fixed locations. the main goal of this work is to evaluate, through simulations, the impact of sinks' mobility in a wireless sensor network created by using the topology formation mechanism provided by the ieee 802.15.4 standard. to this aim, as a practical case study, we consider a wireless sensor network deployed in a museum used to monitor the presence, the localization and other parameters of artworks exposed in it. in this context, we analyze how sinks' mobility affects connectivity and energy consumption for network formation and re-configuration.
novel preamble-based channel estimation for ofdm/oqam systems. ofdm/oqam has been considered as an attractive alternative to classic ofdm with cyclic prefix (cp) over doubly dispersive channels. by utilising well designed pulse shapes and removing cp, ofdm/oqam has the advantage of reduced out-of-band energy and a theoretically higher spectral efficiency. however, channel estimation over doubly dispersive channels has been a big problem for ofdm/oqam due to the nonorthogonality between the real and imaginary parts of its modulated signals. therefore conventional channel estimation (ce) methods used for ofdm cannot be directly applied to ofdm/oqam. recently a preamble-based ce method - interference approximation method (iam) - has been proposed to ease this task. by treating the intrinsic interference from neighbour symbols as known information, two heuristic preamble sequences have been constructed based on tentative observations, which turn out to be suboptimal. in this paper, we present a general theoretical framework for iam preamble design and apply it to identify the optimal iam preamble sequence which results in a higher gain. numerical results have verified the effectiveness of the theoretical framework and a gain of 2.4 db against cp-ofdm has been demonstrated with the new preamble in various doubly dispersive channels with a qpsk modulation.
distributed turbo coding with information transfer via timing of the half-duplex relay-phases. we consider a wireless half-duplex relay communication from a source to a destination with a distributed turbo code. the source broadcasts code-bits to relay and destination during the relay-receive phases, the relay decodes and transmits additional code-bits to the destination during the relay-transmit phases. we propose to use the timing of the relay-receive and relay-transmit phases to transfer more additional code-bits to the destination at the cost of stricter synchronization requirements. moreover, it is required that the relay is able to switch its state rapidly between receiving and transmitting from symbol to symbol. the destination does not know the timing of the relay-receive and relay-transmit phases a priori and has to distinguish the transmissions of source and relay due to the received amplitude. the received amplitude at the destination is higher for transmissions of the relay because the relay-destination link is stronger than the source-destination link. a constant-weight code is used to determine the timing of the relay-receive and relay-transmit phases. simulation results for an example show a substantial gain of the proposed extension.
on the use of multi-objective optimization algorithms for solving the impairment aware-rwa problem. in future transparent optical networks, it is important to consider the impact of physical impairments in the routing and wavelengths assignment process, to achieve efficient connection provisioning. in this paper, we use classical multi-objective optimization (moo) strategies and particularly genetic algorithms to jointly solve the impairment aware rwa (iarwa) problem. fiber impairments are indirectly considered through the insertion of the path length and the number of common hops in the optimization process. it is shown that blocking is greatly improved, while the obtained solutions truly converge towards the pareto front that constitutes the set of global optimum solutions. we have evaluated our findings, using an q estimator tool, that calculates the signal quality of each path analytically.
crosstalk cancellation in upstream coordinated dsl using an iterative mmse receiver. in this paper, we address the problem of the presence of spatial correlated noise in upstream coordinated dsl systems. the performance of a minimum mean-squared-error (mmse) iterative receiver structure without whitening the noise is evaluated. a simplified mmse receiver based on the approximation of matrix inversion in the iterative process is presented. the convergence of the iterative scheme in this scenario is predicted using exit charts under realistic transmission conditions.
space-time block codes with symbol-by-symbol maximum likelihood detections. this paper presents a new set of quasi-orthogonal space-time block codes (qostbcs) with symbol-by-symbol maximum likelihood (ml) detections for four transmit antennas over quasi-static rayleigh fading channels. each of them is analytically proved to achieve full diversity and the same coding gains as the coordinate-interleaved orthogonal design by individually using their optimal constellation rotations over arbitrary qam or 4m-psk constellations. previous designs are included in our systematic formulation as well. together with the simulation results, the coding loss paying for simplifying the optimal decoders from complex symbol pairwise to symbol-by-symbol ml detections is found asymptotically equal to 0.21 db, for the qostbcs achieving full diversity and the optimal coding gains over general qam constellations.
reflected simplex codebooks for limited feedback mimo beamforming. this paper proposes reflected simplex codebooks for limited feedback beamforming in multiple-input multiple-output (mimo) wireless systems. the codebooks are a geometric construction based on simplices and the an lattice. we propose a fast codebook search and indexing algorithm. we show that such codebooks perform superior or comparable to other codebooks, with much lower implementation complexity.
a secure solution for ubiquitous multimedia broadcasting. ubiquitous multimedia applications are becoming more and more popular. however, the solutions that confirm content and interaction security in these applications are still open issues because of various network convergences and device interconnections. this paper investigates a ubiquitous multimedia scheme and proposes a secure service solution. in the ubiquitous scheme, the multimedia content is encoded with scalable video coding and broadcasted via digital video broadcasting for handheld terminals (dvb-h) to mobile terminals, the access right is transmitted by global system for mobile (gsm) channel, and the media content and access right can also be transmitted from mobile terminals to home tv through wifi based wireless local area network. the proposed secure solution supports three kinds of business models by using various content encryption modes and secure interaction protocols. the solution's security is evaluated and discussed. since few works have been done to solve this problem, this paper is expected to attract more researchers.