waashk/dblp huggingface dataset:
hmm-web: a framework for the detection of attacks against web applications. nowadays, the web-based architecture is the most frequently used for a wide range of internet services, as it allows to easily access and manage information and software on remote machines. the input of web applications is made up of queries, i.e. sequences of pairs attribute←value. a wide range of attacks exploits web application vulnerabilities, typically derived from input validation flaws. in this work we propose a new formulation of query analysis through hidden markov models (hmm) and show that hmm are effective in detecting a wide range of either known or unknown attacks on web applications. in addition, despite previous works, we explicitly address the problem related to the presence of noise (i.e., attacks) in the training set. finally, we show that performance can be increased when a sequence of symbols is modelled by an ensemble of hmm. experimental results on real world data, show the effectiveness of the proposed system in terms of very high detection rates and low false alarm rates.
dynamic resiliency analysis of key predistribution in wireless sensor networks. wireless sensor networks have been analyzed for more than a decade from operational and security points of view. several key predistribution schemes have been proposed in the literature. although valuable and state-of-the-art proposals have been made, their corresponding security analyses have not been performed by considering the dynamic nature of networking behavior and the time dimension. the sole metric used for resiliency analysis of key predistribution schemes is "fraction of links compromised" which is roughly defined as the ratio of secure communication links that the adversary can compromise over all secure links. however, this metric does not consider the dynamic nature of the network; it just analyzes a snapshot of the network without considering the time dimension. for example, possible dead nodes may cause change of routes and some captured links become useless for the attacker as time goes by. moreover, an attacker cannot perform sensor node capturing at once, but performs over time. that is why a methodology for dynamic security analysis is needed in order to analyze the change of resiliency in time a more realistic way. in this paper, we propose such a dynamic approach to measure the resiliency of key predistribution schemes in sensor networks. we take the time dimension into account with a new performance metric, "captured message fraction". this metric is defined as the percentage of the messages generated within the network to be forwarded to the base station (sink) that are captured and read by the attacker. our results show that for the cases where the static fraction of links compromised metric indicates approximately 40% of the links are compromised, our proposed captured message fraction metric shows 80% of the messages are captured by the attacker. this clearly proves the limitations of the static resiliency analysis in the literature.
two phase spectrum sharing for frequency-agile radio networks. modern frequency-agile radios are capable of dynamically changing the spectrum width and central frequency of its channels. existing spectrum sharing algorithms often fail to exploit this characteristic to realize efficient spectrum utilization. in this paper, we present a theoretical framework that capitalize on the frequency agility of modern radios. we solve a joint spectrum sharing and end-to-end rate control problems for general wireless networks to achieve optimal spectrum efficiency with regard to network utility. analytical and simulation results show the effectiveness of our design.
bandwidth and computing resources provisioning for grid applications and services. applications using grid computing infrastructure usually require resources allocation to satisfy their quality of service (qos) requirements. given that the grid infrastructure is a set of computing resources geographically distributed, the support of grid applications requires the allocation of computing resources and bandwidth to enable communication among these resources. the objective is to accommodate as many applications as possible while still satisfying their requirements. ideally, we would like to accommodate a given grid application using a set of computing resources (e.g., one server) that are not geographically distributed (e.g., in the same lan); however, this is not always possible. indeed, to increase the probability of accommodating grid applications, we may need to use computing resources scattered all over the network; in this case, bandwidth allocation is required to enable communication among these resources. in this paper, we propose an optimization model that enables the "simultaneous" allocation of computing resources and bandwidth for grid application while maximizing the number of grid applications being accommodated. a heuristic is proposed to solve the model with an acceptable response time; simulations show that the proposed approach outperforms existing classical approaches.
optimizing access radio in multi-radio mesh network. this paper discusses a hierarchical multi-radio mesh network, where the normal clients associate with the mesh ap through the access radio and then the mesh aps communicate with each other via the mesh radio. while most of the existing studies focus on the performance issue for the mesh nodes communication with the mesh radio, in this paper, we argue that the channel assignment for the access radio will affect the overall system significantly. in this paper, we try to exploit the information exchange among the mesh nodes to help the access radio channel selection. a new metric, effective channel air time (ecat), is proposed for channel assignment under this multi-radio mesh network. ecat can work well when there are traffics in the overlapping channels. a real testbed has been developed to demonstrate the effectiveness of the proposed metric and scheme.
adaptive hybrid call admission control policy for umts with underlying tunnel-wlans heterogeneous networks. in this paper we evaluate the handoff performance of an umts network with underlying tunnel-wlans at the cell periphery while developing an adaptive qos oriented cac function, proposed to limit the occurrence of hard ieee 802.11 wlan-umts handovers to mobiles using real time applications. the proposed protocol is hybrid and based on the service class differentiation, the location in the heterogeneous infrastructure and a vertical handoff decision function as well. the results show that our policy achieves significant performance and gains. it maximizes the utilization of the resources available at the wlan cells, and meets as much as possible the qos requirement of higher priority users.
a generalized two-way relay channel with private information for the relay. in the conventional two-way relay channel, two sources exchange information with help from a relay. we introduce a generalized two-way relay channel where each source additionally sends private information to the relay. for this channel, we consider a protocol that consists of a multiple-access (ma) phase and a broadcast (bc) phase and obtain achievable rate regions for both phases. the ma phase is related to computation over the multiple-access channel (mac).we show that our scheme achieves rates that always lie within half bit of the capacity region for computation over mac, and is capacity achieving in the bc phase. this near optimality in the ma phase can be achieved by time sharing a capacity-achieving code for the mac and a superposition code that uses a lattice code as its component code.
performance analysis of verification-based decoding for packet-based ldpc codes over binary symmetric channel. in this paper, we propose a statistical model to analyze the performance of verification-based algorithm (va) for packet-based low-density parity-check (ldpc) codes over binary symmetric channel (bsc). in contrast to the analysis of va in the literature, we propose to take the false verification into consideration. for a given ensemble of ldpc codes and channel parameters, the proposed analysis model gives an efficient way to find the average performance of packet-based ldpc codes with verification-based decoding. through numerical results, we find that the proposed method can provide a close estimation of frame error rate (fer) for packet-based ldpc codes with verification-based decoding over bsc for all crossover probabilities of practical interests.
capacity with probabilistic delay constraint for voice traffic in a rayleigh channel. the capacity with probabilistic delay constraint cdt,ɛ expresses the maximum source rate that may be supported in a wireless system with a probability ɛ of exceeding certain delay bound dt. in [1], cdt,ɛ was calculated for a rayleigh channel carrying a constant rate flow. in this work, the potential of the effective bandwidth theory is shown by evaluating this constrained capacity for a variable rate source modeled as an on-off process. cross relations among on-off process parameters, fading channel statistics, qos constraints and maximum allowable mean source rate are displayed by the obtained closed-form expressions. cdt,ɛ is measured in different scenarios to exhibit to which extent higher time-correlation of the channel response or longer on-off periods are harmful to the delay behaviour, getting a lower value of the capacity cdt,ɛ.
adaptive sensor activation for target tracking in wireless sensor networks. this paper presents an adaptive sensor activation for target tracking in wireless sensor networks by dynamically adjusting the range of sensor selective activation instead of fixed one. a closed-loop control algorithm for the range of adaptive sensor activation is designed according to the online feedback of the tracking quality. the failed tracking case can also be handled by the proposed algorithm. extensive simulation results show that the adaptive sensor activation achieves higher performance in terms of tracking effect and energy efficiency.
design and deployment of a network-aware grid for e-science applications. in the last years, grid computing has emerged as a valuable service to solve complex computational problems in many scientific and industrial domains. quality of service (qos) provision for these applications is therefore a key challenge for high speed next generation networks and cross-layer mechanisms, enabling the development of network-aware grids, should be introduced. this paper takes into account, as a case study, an application for the simulation of particles coagulation phenomena. a parallel direct simulation monte carlo algorithm has been implemented and extensive computations have been performed in a cluster of computing nodes to evaluate the execution time of the application in different operating conditions. then, data collected from these experiments, have been used as input for the design and deployment of a network-aware grid infrastructure. since this application is characterized by frequent data exchanges, the impact of the allocated bandwidth on the overall application's performance has been investigated.
design of a codebook structure for a progressively linear pre-coded closed-loop mimo hybrid arq system. the paper considers a hybrid arq (harq) scheme for a linear pre-coding-based closed-loop multiple-input multiple-output (mimo) system, in which a pre-coding matrix is dynamically selected for every retransmission by taking into account a symbol-level combining gain obtained from the previous receptions. a new retransmission structure with a sequence of multiple codebooks is proposed that are optimized for combining gain, rather than using a single identical codebook for every retransmission. furthermore, a criterion for selecting a pre-coding matrix for each retransmission can be provided so as to minimize the retransmission error probability. under the proposed multiple codebook structure for mimo-harq systems, a sequence of optimum codebooks is constructed for the subsequent retransmissions. simulation results are presented for showing that the proposed scheme achieves significant error performance advantages over conventional schemes with a single codebook and furthermore, a near-optimal performance is achieved as the codebook size chosen is large enough.
improved fast recursive algorithms for v-blast and g-stbc with novel efficient matrix inversion. in this paper, we propose a novel matrix inversion algorithm, which speeds up the corresponding step in the existing fast recursive algorithm for vertical bell laboratories layered space-time architecture (v-blast) by 1.67. totally our improved recursive algorithm for v-blast speeds up the existing recursive algorithm for v-blast by 1.3. furthermore, we develop an efficient recursive algorithm to implement the minimum mean-square error (mmse) successive interference cancellation (sic) detector with optimal ordering for groupwise space-time block coded system (g-stbc), by exploiting the properties of the alamouti structure in the equivalent channel matrix for gstbc. our recursive algorithm for g-stbc speeds up the low-complexity mmse sic algorithm with sub-optimal ordering for g-stbc by 2.57 approximately.
on accurate and scalable anomaly detection in next generation mobile network. this paper proposes an adaptive sampling strategy to address the accuracy and scalability issues of anomaly detection at high-speed backbone side of next generation mobile network (ngmn). the proposed sampling strategy is formulated based on the network traffic condition. it is constituted by two important functions namely the traffic identification and the sampling decision. while the former utilizes spectral analysis to identify the severity status of the traffic flows, the latter exploits both the flow status and flow size to compute the optimal sampling rate. in addition, a renormalization process is proposed to address the scalability issue in the network. our analysis demonstrates that the proposed technique is efficient in providing adequate statistics for detecting anomaly traffic and scales well to the high speed traffic of ngmn.
a directional mac protocol with deafness avoidance for uwb wireless sensor networks. ultra-wideband (uwb) is a key solution for wireless connectivity, characterized by ultralow power consumption and a good degree of robustness to interference. evidence of its importance, is its recent use in the ieee 802.15.4a standard. uwb technology with joint consideration of directional antennas can benefit when compared to classical omnidirectional antennas from the energy conservation viewpoint, which is of fundamental concern when it comes to wireless sensor networks (wsns). however, exploiting directionality requires new approach in the design of a medium access control (mac) protocol to be applied. in this work, idle nodes continuously rotate their receiving beams over 360 degrees until a predefined preamble trailer is detected. the resulting scheme is a directional ultra-wideband mac protocol, named du-mac, which deals effectively with the problem of deafness and the problem of determination of neighbors' location. simulation based studies would demonstrate the effectiveness of our protocol in many critical parameters.
security in advanced optical communication networks. the increased demand of data services within the last few years has prompted a commensurate explosion in transportable bandwidth, most of which contain sensitive information, personal data, bank accounts, credit card numbers, proprietary documents, and more. as a result, there are two types of security in communications, securing user data and securing the physical network. the first is addressed with encryption algorithms, the unbreakability of which does not depends so much on the sophistication of the algorithm but on the difficulty to break it using a sequential computer; that is, it capitalizes on the inability of the attacker to use a fast supercomputer. the second is not a well addressed topic, particularly in modern fiber-optic networks. one attempt to create an unbreakable cipher-text is quantum cryptography that emanated from quantum mechanics; this method capitalizes on the no-cloning principle of particular characteristics of photons, such as polarization. in this paper, we examine the security of advanced optical networks, fiber-optic and free space optical (fso). we describe quantum cryptography and the quantum key distribution, including the principle of teleportation, we identify vulnerabilities and we discuss detection mechanisms and countermeasure strategies against attacks on the physical network.
composite hypothesis testing for cooperative spectrum sensing in cognitive radio. in this paper, we present a composite hypothesis testing approach for cooperative spectrum sensing. we derive the optimal likelihood ratio test (lrt) statistic based on the neyman-pearson (np) criterion at the fusion center for both hard (one-bit) and quantized (multi-bit) local decisions. we show that the lrt statistic depends on the modulation type and second-and fourth- order statistics of the primary signal. however, such side information is not commonly available to the secondary network. therefore, we propose to apply composite hypothesis testing methods, such as the rao test, which do not require any prior knowledge about the primary signal, in a cooperative sensing scenario. we derive a modified rao test statistic for decision making at the fusion center for both cases of hard and quantized local decisions. we also apply the locally most powerful (lmp) detector at the fusion center for weak primary signals and derive its corresponding test statistic. these methods are much simpler than the optimal np-based method and do not require estimation of the primary signal statistics while having a very close performance to the optimal method.
joint precoding for mimo-relay systems with partial channel state information. in this paper, we propose a joint precoding scheme for both the base station (bs) and relay station (rs) to increase the ergodic capacity of downlink non-regenerative multiple-input multiple-output(mimo)-relay systems. different from previous work, we assume only the mean and the covariance matrix are known for the channel state information (csi) of the rs-mobile station(ms) link. since the exact solution of this problem is difficult to be found because the rs-ms channel is only partially known, we employ precoding matrices that maximize the upper bound on the ergodic capacity. based on this approach, the proposed scheme uses an iterative method to determine both bs and rs precoding matrices simultaneously. in numerical results, the proposed joint precoding scheme is shown to outperform the water-filling and amplify-and-forward (wf-af) scheme in high signal-to-noise ratio (snr) regions. it is also shown to outperform the spatial multiplexing and rs precoding (sm-rp) scheme in low snr regions.
diversity analysis of a randomized distributed space-time coding in an amplify and forward relay channel. this paper considers a cooperative communications system where a single relay aids a point-to-point transmission using an amplify and forward configuration. the relay linearly encodes the k received symbols into n new ones by means of a matrix multiplication, and the destination employs a lmmse filter to estimate the information originally transmitted. a large-snr approximation of the outage probability pout is derived for this system. the analysis of pout shows that the diversity order of the system depends on the ratio k/n: if such a ratio is too high (the relay excessively compresses the information), no diversity is added by introducing the relay. conversely, if this ratio is smaller than a certain quantity, diversity order 2 is ensured. the derived expressions are finally used to establish the diversity-multiplexing tradeoff of the system.
co-opetition strategy for collaborative multiuser multimedia resource allocation. this paper focuses on using the mindset of co-opetition for collaborative multimedia resource allocation. the co-opetition suggests a judicious mixture of competition and cooperation. we present a novel co-opetition strategy based on the kalai-smorodinsky bargaining solution (ksbs), and apply it to video rate allocation. the proposed strategy makes satisfied users stop competing for resources such that qos of unsatisfied users can be improved. our strategy is evaluated through comparing to existing competition-based strategies. numerical results indicate that, the co-opetition strategy can result in an improved number of satisfied users. algorithm with low complexity is also presented.
revisiting relative location estimation in wireless sensor networks. relative location estimation plays an important role of localization in wireless sensor networks (wsns). in wsns with planned deployment of anchor nodes, some prior information may be available. existing work on relative location estimation rarely takes into account the lognormal fading effect of wireless channel and the prior probability of the link distance to each reachable anchor node. as a result, when applied to such environments, they may not work effectively. in this paper, we propose a new model called probability-based maximum likelihood (pml) for relative location estimation. with some prior information, the estimation accuracy can be improved significantly. we also discuss the impact of over-estimation and under-estimation of the distance to each reachable anchor node on the accuracy of relative location estimation, and introduce the concept of the compensation factor to combat such effects. the simulation results show that the proposed pml outperforms existing solutions in terms of estimation accuracy for wsns with planned deployment of anchor nodes.
performance evaluation of contention-based access in ieee 802.16 networks with subchannelization. ieee 802.16 wireless networks, known as wimax, employ a mechanism for guaranteed time allocation to mobile stations in order to meet the different quality of service requirements for service flows. the base station allocates contention-based time slots for the stations to transmit their requests for additional bandwidth. each contention time slot can accommodate a single transmission if there is no subchannelization or multiple concurrent transmissions if the base station enables subchannelization during the contention period. for transmission during this period, each station employs a contention-resolution mechanism. in this paper, we develop an analytical model for the bandwidth request and resolution mechanism during this contention period when subchannelization is employed. the model is shown to accurately model the contention period when subchannelization is enabled. performance metrics, such as throughput and capacity, show that adding more subchannels to the contention time slots increases both the throughput and the capacity of the contention period carrying more successful bandwidth requests. simulations with different parameter sets are carried out to validate the proposed model.