waashk/dblp huggingface dataset:
hybrid resource allocation in wireless ad hoc networks. inefficient resource management may cause problems of reliability of service in shared medium wireless networks. resources include bandwidth, processor cycles and buffers. excessive competition for these resources can cause severe packet collision rates, compound network congestion, or even result in starvation of some nodes. in such a situation, data transmission is subject to very long delays and significant packet losses. although transport layer protocols can help improve end-to-end performance, these approaches are slow in responding to network changes and incur additional overhead. this paper aims to reduce transmission delay and increase packet delivery ratio. a hybrid resource allocation problem is formulated by the primal algorithm and a controller is derived to decrease congestion globally and to reduce collisions locally. our simulation results show that this hybrid controller can achieve packet loss rates close to 1% and significantly shorten end-to-end delay even in a high interference environment with heavy system load. in addition, we also compare the performance of the hybrid controller with the impact of multipath routing. the accuracy of our simulation is improved by adding a probabilistic preamble detection model and sinr collision model based on frame error rate.
a recursive distributed topology discovery service for network-aware grid clients. distributed application (e.g., grid-enabled application) performance is highly dependent on the information available when computational resources are chosen. a resource selection based on computational resource information complemented with network performance information has the potential to be optimal from the application performance viewpoint. this is particularly true for network-intensive distributed applications. this study proposes a recursive distributed topology discovery service (rd-tds) that allows grid clients to retrieve network performance information (i.e., ip-level topology and link capacity) without the need of specific administrative privileges. the rd-tds exploits a selected set of distributed beacons (i.e., measurement points) that recursively probe newly discovered nodes until no undiscovered nodes are found during an exploration step. the rd-tds simulative and experimental evaluation confirms its expected qualities: a rapid and complete discovery of the network performance information with the utilization of a limited number of active beacons. in addition, the proposed method rationale can be easily applied to many current network exploration tools.
adaptive compress-and-forward relaying in fading environments with or without wyner-ziv coding. compress-and-forward is a protocol for transmission over relay networks in which the relay forwards a compressed version of the signal it observes. the compression method used by the relay is source coding with side information, i.e. wyner-ziv coding, since the destination can use the signal it receives directly from the source as side information. this paper addresses the case of a wireless relay network with orthogonal transmissions from the source and the relay terminals; we show that when the transmitters have no instantaneous channel state information the optimal compression parameters often make wyner-ziv coding reduce to conventional source compression, i.e. compression that does not take into account the side information available at the destination. this result simplifies the implementation of the cf protocol in the case we consider, since it shows that in several situations one can use more convenient compression methods without significant performance loss.
four-antenna based structure for cellular networks with frequency reuse factor of one. in this paper, a new four-antenna based structure (fas) is introduced for capacity improvement in future cellular networks with frequency reuse factor of 1. in fas, each cell consists of one omni-directional antenna located at the cell center and three 120-degree directional antennas located at the cell edge. in order to achieve effective system bandwidth allocation among four antennas, novel spectrum planning schemes for both downlink (dl) and uplink (ul) are proposed. theoretical analysis and simulation demonstrate that the proposed cellular structure can significantly improve the system capacity in both dl and ul, especially at the cell edge.
resource allocation in an lte cellular communication system. the problem of allocating resources for user transmissions on the downlink of a long term evolution (lte) cellular communication system is studied. a novel optimal multiuser scheduler is proposed and its performance is evaluated. numerical results show that the system performance improves with increasing correlation among ofdma sub-carriers. it is found that a limited amount of feedback information can provide a relatively good performance. a sub-optimal scheduler with a lower computational complexity is also proposed, and shown to provide good performance. the sub-optimal scheme is especially attractive when the number of users is large, as the complexity of the optimal scheme may be unacceptably high in many practical situations.
a fuzzy logic based scheme to detect adaptive cheaters in wireless lan. the most commonly used medium access mechanism in wlan is based on the csma/ca protocol. this protocol schedules properly the access to the medium among all competing nodes. however, in a hostile environment, such as wireless local area networks (wlans), selfish or greedy behaving nodes may prefer to decline the proper use of the protocol's rules in order to increase their bandwidth shares at the expense of well behaving nodes. in this paper, we focus on one such misbehavior and in particular on the adaptive greedy misbehavior of a node in the context of wireless local area network environment. in such environment, wireless nodes compete to gain access to the medium and communicate directly with an access point (ap). in this case, a greedy node may violate the common rules in order to earn extra bandwidth upon its neighbors. in order to avoid its detection, this node may adopt intelligently different techniques and switch dynamically between each of them. to counter such a misbehavior, we propose the use of a fuzzy logic technique in a new detection scheme. this scheme, implemented in the access point, monitors the behavior of associated wireless nodes and reports any deviation from the proper use of the csma/ca protocol. the simulation results of the proposed scheme show its robustness and ability to detect and identify quickly most of the deviations of an adaptive cheater.
low-complexity equalization based on least squares support vector classifiers for ds-uwb systems. we propose the least squares support vector classifier (ls-svc) based equalization schemes for direct sequence ultra wideband (ds-uwb) systems, where a bank of independent ls-svcs are employed to detect each block of signals. the ls-svc based equalizers provide a close bit error rate (ber) performance in the line-of-sight (los) scenario to the case with additive white gaussian noise (awgn). simulation results show that the ls-svc based equalizers have almost identical ber performance to that of typical support vector classifiers (svcs) with a reduced training complexity. furthermore, the sparse lssvcs are employed to reduce the detection complexity, with little performance loss compared to ls-svcs.
managing distributed feature interactions in enterprise sip application servers. several trends in sip application server deployments in large scale telephony environments exacerbate the classic problem of feature interaction : use of distributed feature servers, mixing of legacy and green-field feature servers, and the co-existence of multiple third-party feature implementations provisioned in the same environment. next-generation sip application servers will include an application router (ar) to provide more application control over feature sequencing. as we discuss here, the ar can be augmented to incorporate feature interaction detection and resolution logic. we describe a novel design for run-time feature interaction detection and resolution in an environment of distributed feature servers using a sip application server with application routing function, such as that defined in jsr 289. the approach is based on the algorithm of the kolberg-magill (k-m) method for feature interaction detection. here we extend the notation of the algorithm to cover advanced call control services, enable the algorithm to work in topologies involving b2buas (back-to-back user agents) and sbcs (session border controllers), and test the approach with a substantial feature set of 32 features found in large enterprise solutions.
on opportunistic beamforming in fast fading scenarios. we comment on the famous work «opportunistic beamforming using dumb antennas» by p. viswanath, d.n.c. tse, and r. laroia, from 2002. in that paper, it is argued that in an independent and fast fading environment, the opportunistic beamforming technique provides no performance gain. this assessment is based on the argument that the fading distribution of the equivalent channel, which is obtained through opportunistic beamforming, does not depend on the number of transmit antennas in independent and fast fading scenarios. in this paper, we show that this argument of the original work is based on a non-physical model of rayleigh fading, and as a consequence, results in a wrong conclusion. in contrast, we show that there is beamforming gain to be obtained by the opportunistic beamforming technique even for independent and fast fading environments. for the case of uncoupled antennas, the amount of obtainable beamforming gain approaches-with probability one-the number of transmit antennas from below as the number of users approaches infinity.
a resource-efficient traffic localization scheme for multiple bittorrents. the emergence of peer-to-peer (p2p) applications has posed a threat to the operating cost of internet service providers (isps) due to the large amount of inter-isp traffic generated. the problem stems from the mismatch between the p2p overlay network formed randomly and the underlying physical network. recently, bittorrent has attracted enormous users by its convenience of large-scale content distribution and has also become a major challenge for isps. therefore, in this paper we proposed an effective b-proxy scheme to evaluate through realistic simulation on planetlab, where hundreds of bittorrent clients were executed during the experiment. simulation results show that more than thirty percent of inter-isp traffic could be saved in a torrent with a relatively small cache size consumed which is only eighth times that of the original file.
a partial-protection approach using multipath provisioning. we study the problem of reliably provisioning traffic using multipath routing in a mesh network. traditional approaches handled reliability requirements using full-protection schemes. although full-protection approaches offer high assurance, this assurance can be costly. we take a less expensive approach to maintain reliability by offering partial-protection. specifically, our approach guarantees part of the requested bandwidth, rather than the full amount, in the event of a link failure. we first show that the amount of partial-protection that can be guaranteed is limited by the topology of the network and the bandwidth requirement of a connection request. we then propose an effective multipath algorithm that attempts to provision bandwidth requests while guaranteeing the maximum partial-protection possible. results show that by effectively selecting paths that limit edge overuse, our algorithm achieves very low bandwidth blocking probability. our algorithm also serves significantly more requested bandwidth than the protection approach.
iterative detection and decoding for hard-decision forwarding aided cooperative spatial multiplexing. in this paper, the optimal decoding strategy for cooperative spatial multiplexing (csm) aided systems is derived. in csm systems, the multiple relay stations (rss), which compose a virtual antenna array (vaa), independently decode the packets received from the mobile stations (ms) and forward them to the base station (bs). when the bs decodes the signal forwarded from the rss, the potential decoding errors encountered at the rss will result in erroneous forwarding, but their effects are mitigated by the proposed solution. our simulation results show that when the direct link has a significantly higher signal-to-noise ratio than the relay link, the proposed decoding algorithm achieves an approximately 3 db better performance than conventional csm, which does not consider the deleterious effects of erroneous forwarding from the rss.
distributed reallocation scheme for virtual network resources. network virtualization is an emerging technology for cost-effective sharing of network resources. the key strategy in network virtualization is of slicing physical resources (links, cpu, memory, and storage) to create virtual networks that are assigned to different operators. one important challenge on network virtualization is the efficient use of the physical resources. to accomplish such efficient use the management of the physical resources should be transparent to the applications running within the virtual networks, and should be executed at runtime in order to deal with the variation on the load requests of different virtual networks. traditional resource allocation schemes use offline, centralized, and global view strategies to manage the use of physical resources. in contrast to these strategies, we propose a runtime, distributed, local view approach to manage physical resources. in this paper we introduce a virtual network architecture and an associated self-organizing algorithm to reallocate virtual network resources along different physical nodes in order to equalize the bandwidth, and storage consumption on the physical nodes. we developed a virtual network model based on omnet++ to simulate the designed self-organizing algorithm. an iptv testbed scenario is presented and initial experiments, about the interruption time of the application inside the iptv virtual network, are described.
multipurpose image watermarking based on the wavelet tree contrast level transformation. multipurpose image watermarking algorithms can achieve the goal of content authentication and copyright protection simultaneously. in this paper, we propose a wavelet tree based blind watermarking algorithm using contrast level transformation. the wavelet coefficients of the host image are grouped into trees. the robust watermark and the semifragile watermark are embedded by quantizing one tree and resetting the other. with level change compensation, the watermarked image has high fidelity to the original one since the difference is minimized. both of the watermarks can be independently extracted without the original image. the simulation results have demonstrated the effectiveness of the proposed algorithm in terms of robustness compared with other wavelet tree based technique.
security games with incomplete information. we study two-player security games which can be viewed as sequences of nonzero-sum matrix games played by an attacker and a defender. at each stage of the game iterations, the players make imperfect observations of each other's previous actions. the underlying decision process can be viewed as a fictitious play (fp) game, but what differentiates this class from the standard one is that the communication channels that carry action information from one player to the other, or the sensor systems, are error prone. two possible scenarios are addressed in the paper: (i) if the error probabilities associated with the sensor systems are known to the players, then our analysis provides guidelines for each player to reach a nash equilibrium (ne), which is related to the ne of the underlying static game; (ii) if the error probabilities are not known to the players, then we study the effect of observation errors on the convergence to the ne and the final outcome of the game. we discuss both the classical fp and the stochastic fp, where for the latter the payoff function of each player includes an entropy term to randomize its own strategy, which can be interpreted as a way of concealing its true strategy.
blind detection of interleaver parameters for non-binary coded data streams. interleaving, which is commonly used to combat bursts of errors, is an important technique in digital communications systems. the blind detection of interleaving parameters has been studied by many researchers for forward-error-correction (fec) encoded binary data streams. in this paper, we use finite field gauss elimination with pivoting to blindly estimate interleaving period of non-binary data streams. to be specific, the data streams are encoded by reed solomon codes. suppose the percentage of zeros in each column of the analytical matrix block is denoted as φ0. numerical results show that both the variance and the mean of φ0 can be used as the evaluation parameter to detect the interleaving parameters. however, the former approach provides a 1-db gain over the latter.
do next generation networks need path diversity? we have currently reached a phase where big shifts in the network traffic might impose to rethink the design of current architectures, and where new technologies, being pushed into market, will act as enabler of such changes. taking into account the current scenario and its likely evolution as well, in this paper we examine the case for multi-path routing within the metropolitan access network. through an optimization framework, we undertake the analysis of several interesting aspects of the problem, such as i) the user access technology, ii) the topology of the access network and iii) the traffic locality ratio within the access. by numerical solution of the problem we quantify the potential gain given by path-diversity: our results confirm the appeal of multi-path routing strategies both from the user and the network perspectives.
qos of video delivered over 802.11e wlans. many home networks now use 802.ll wireless local area networks (wlan)s. the 802.11e amendment has been designed to improve quality of service (qos) over these networks allowing for multimedia applications such as iptv to be better supported. the h.264 video compression standard is suitable for iptv due to its high compression and error resilience. video packets of different slice types are of varying importance to the decoded video quality so can be mapped into different priority queues using 802.11e enhanced distributed channel access (edca). we investigate several mapping schemes for a variety of video content to see how the quality of the decoded video is affected as the number of concurrent video connections is increased. the different mapping schemes exhibit different loss patterns in the video sequences and their impact on the video quality is content dependent. subjective tests were therefore carried out which allow us to perform an accurate and valid assessment of the video quality. packet loss rate is also reported. our results show that as the number of concurrent videos approaches the network capacity some mapping schemes show a cliff-edge drop in quality while others offer a more acceptable gradual quality degradation. these schemes cause b-frames to be dropped and in effect reduce the video frame rate. these schemes are more successful for videos that have low or medium temporal activity.
subset selection in type-ii hybrid arq/fec for video multicast. this paper proposes an error control scheme that minimizes the total distortion experienced by the receivers using a new version of type-ii hybrid arq/fec. based on the feedback information about the losses in the previous group of pictures (gop), the server sends parity packets for a subset of the frames from that gop with the aim of minimizing the total distortion experienced by the receivers. the subset selection problem is np-hard, so we propose a suboptimal method to solve it based on simulated annealing. experimental results for the case when a single parity packet is used per group of 16 packets show that the proposed subset selection improves the plain type-ii hybrid arq/fec by over 4 db in decoded video psnr, and achieves a 1-1.5 db gain compared to a state-of-the-art error control method based on rate-distortion optimized frame retransmission.
on the cache-and-forward network architecture. in order to meet the increasing demands of content dissemination in internet, we propose a novel architecture for the future internet called cache-and-forward (cnf), which transports content as "packages" in a hop-by-hop manner towards the destination, instead of transporting a stream of fragmented packets along an established tcp/ip connection. in this paper, we discuss how the cnf network architecture can be designed for efficient content retrieval. we first introduce several specific services provided in cnf network which are centered around content handling and mobile access. we then give an overview of the cnf protocol stack, which is built on top of ip, and consists of a data plane and a control plane. we provide detailed descriptions of each protocol within both planes. then we present two caching algorithms, where one involves each cnf router making independent decisions on content caching while the other coordinates node caching within an autonomous system (as) through hashing. finally, we gave the initial simulation results to show the performance benefits of hop-by-hop transport and content caching.
using session identifiers as authentication tokens. as authentication provides crucial online identity, it is the basis of data security. in this paper, a session based authentication is proposed and the long unique un-guessable session identifier is used as a parameter of an authentication token. it has the advantages of one-timeness, short-lived and no prior knowledge requirement. the session model is established with detailed implementation of communication protocol. the security of this protocol is then analyzed formally and the results show that the protocol can resist various attacks, e.g. session hijacking, message replay and pharming attacks etc. finally, a case is studied and the performance of the application is evaluated, which indicates that the proposed scheme is simpler and more efficient than the existing schemes.
low complexity variational bayes iterative receiver for mimo-ofdm systems. a low complexity iterative receiver is proposed in this paper for mimo-ofdm systems in time-varying multi-path channel based on the variational bayes (vb) method. according to the vb method, the estimation algorithms of the signal distribution and the channel distribution are derived for the receiver.with the aid of the soft-output qrd-m algorithm, whose complexity is fixed and relatively low, the signal distribution can be obtained conveniently. in particular, a sequential channel estimation algorithm, which completely avoids the computation of matrix inversion and multiplication, is introduced for the channel distribution estimation. moreover, the distribution estimations of the signals and the channels are performed in a cyclical iteration way. the simulation results show that the performance loss of the proposed receiver is only 1db for fast varying channels and less than 0.5db for slow varying channels at the bit error rate of 10-4after 3 iterations, compared with the optimum receiver with perfect channel state information.