waashk/dblp huggingface dataset:
low complexity resource allocation algorithm for ieee 802.16 ofdma system. adaptive resource allocation including the allocation of subcarrier, bit and power in orthogonal frequency division multiple access (ofdma) system, can significantly improve spectral efficiency, increase capacity, and reduce power consumption. the resource allocation in an ofdma system is normally modeled as a combinatorial optimization problem involving a nonlinear objective with nonlinear constraints. this leads to high computation complexity that is only solvable online. in this paper we first develop a nonlinear optimization model of ofdma resource allocation that incorporates not only the throughput constraint but also the delay constraint. we then find an equivalent linear formulation to this optimization problem to facilitate analysis. moreover, we develop a heuristic approximation algorithm to provide a close solution to the equivalent linear programming problem. the heuristic algorithm is efficient enough for on-line adaptive resource allocation. simulation results show that the heuristic solution can achieve almost same capacity but with less computation complexity.
intelligent service monitoring and support. intelligent service management techniques play an important role in the continuously and rapidly evolving area of technologically advanced services. high tech companies are looking for better ways to deliver and preserve services to their customers in a competitive way. this paper introduces a new architecture for a scalable service monitoring and support system called call home analysis and response system (chars). the proposed system utilizes data de-noising and filtering techniques to meet the service management requirements of large-scale service deployments. the system utilizes intra and inter-element correlation of events to enhance the services delivered to end-users. our results demonstrate that the proposed system is effective in covering the performance and fault management aspects for large-scale deployments of advanced services.
joint computing and network resource scheduling in a lambda grid network. data-intensive grid applications require huge data transfers between grid computing nodes. these computing nodes, where computing jobs are executed, are usually geographically separated. a grid network that employs optical wavelength division multiplexing (wdm) technology and optical switches to interconnect computing resources with dynamically provisioned multigigabit rate bandwidth lightpath is called a lambda grid network. a computing task may be executed on any one of several computing nodes which possesses the necessary resources. in order to reflect the reality in job scheduling, allocation of network resources for data transfer should be taken into consideration. however, few scheduling methods consider the communication contention on lambda grids. in this paper, we investigate the joint scheduling problem while considering both optical network and computing resources in a lambda grid network. the objective of our work is to maximize the total number of jobs that can be scheduled in a lambda grid network. an adaptive routing algorithm is proposed and implemented for accomplishing the communication tasks for every job submitted in the network. four heuristics (fifo, estf, ljf, rs) are implemented for job scheduling of the computational tasks. simulation results prove the feasibility and efficiency of the proposed solution.
sdma for 60ghz gigabit wireless networks. with the opening of the 60 ghz spectrum for wlans, there has been a great deal of interest in academia and industry on how best to exploit the more than 5 ghz of available bandwidth. one goal in the wireless community has been delivering gigabit data rates to end users. for this, a variety of approaches have been studied in the past. in this paper, we present two sdma (spatial division multiple access) algorithms that exploit the peculiar propagation properties of this part of the frequency. we show that in typical indoor environments, one access point can deliver over 8 gbps total throughput while using only 640 mhz of the bandwidth. we generalize the algorithms to the case when multiple channels are available and show that with seven channels, we get aggregate throughput of over 31 gbps.
performance analysis of slotted aloha with multi-access-point diversity. slotted aloha is an effective random access protocol and can also be an important element of more advanced media access protocols. this paper investigates slotted aloha in a radio environment with multiple access points. specifically, we examine the impact of multi-access-point (multi-ap) diversity on the performance of slotted aloha. the paper considers both omni-directional (om) and beamforming (bf) antennas at transmission nodes. this leads to the investigation and comparison of four different network scenarios, i.e., om with multi-ap diversity, om without multi-ap diversity, bf with multi-ap diversity and bf without multi-ap diversity. performance evaluations and comparisons are presented in terms of throughput.
resources allocation for the transmission of scalable images on ofdm systems. in a frequency selective channel for wireless applications, we provide a new resources allocation procedure that enables the transmission of scalable images in accordance with end-to-end quality of service (qos) constraints. this scheme is based on an unequal error protection (uep) policy with the possible truncation of the source data layers (after the source coding stage) and an optimal use of the available resources for each layer (with local flattening over the channel portion). the proposed algorithm is applied to the transmission of jpeg- 2000 scalable images over an ofdm channel. we analyze the performance of our method in term of perceived quality and speed, and show better results than state-of-the-art uep schemes.
on construction of moderate-length ldpc codes over correlated erasure channels. the design of moderate-length erasure correcting low-density parity-check (ldpc) codes over correlated erasure channels is considered. although the asymptotic ldpc code design remains the same as for a memoryless erasure channel, robustness to the channel correlation shall be guaranteed for the finite length ldpc code. this further requirement is of great importance in several wireless communication scenarios where packet erasure correcting codes represent a simple countermeasure for correlated fade events (e.g., in mobile wireless broadcasting services) and where the channel coherence time is often comparable with the code length. in this paper, the maximum tolerable erasure burst length (mtbl) is adopted as a simple metric for measuring the code robustness to the channel correlation. correspondingly, a further step in the code construction is suggested, consisting of improving the ldpc code mtbl. numerical results conducted over a gilbert erasure channel, under both iterative and maximum likelihood decoding, highlight both the importance of the mtbl improvement in the finite-length code construction and the possibility to tightly approach the performance of maximum distance separable codes.
routing and spectral efficiency in fading with alamouti coding at two parallel relays. this paper compares direct and relayed transmission in a simple four node configuration with a source, a destination and two parallel relays. the channel model assumes additive white gaussian noise, attenuation from path loss, and slow rayleigh fading. the two parallel relays use the alamouti code to relay data to the destination. using outage probability as a metric, we investigate the relative advantage of relaying as a function of relay placement and the required end-to-end spectral efficiency. we first quantify the benefit derived from adding a second relay to a one-relay network; we then calculate the "critical" rate, above which direct transmission always yields a lower outage probability. it is seen that the critical rate for a two-relay system (with diversity combining) is only modestly higher than that of a one-relay system - suggesting that the addition of more parallel relays is not an effective means of increasing the range of end-to-end rates over which relaying provides an advantage over direct transmission.
a self-organized spectrum assignment strategy in next generation ofdma networks providing secondary spectrum access. this paper proposes a self-organized spectrum assignment strategy in the context of next generation multicell orthogonal frequency division multiple access networks. the proposed strategy is able to dynamically find spectrum assignments per cell depending on the spatial distribution of the users over the scenario, opening new spectrum access opportunities for secondary spectrum usage. reinforcement learning methodology has been employed to implement the strategy, which compared with other fixed and dynamic spectrum assignment strategies shows the best tradeoff between spectral efficiency and quality-of-service while releases spectrum in large geographical areas.
resource allocation for frequency-selective fading, multi-carrier systems with fairness constraints. we consider the problem of fair resource allocation for multi-carrier systems. opportunistic scheduling exploits the time-varying, location-dependent channel conditions to achieve multi-user diversity. previous work in this area has focused on the single-user scheduling in single-carrier systems over a narrowband flat-fading channel, where only one node is scheduled at a time. in wideband multi-carrier systems, multiple nodes can be scheduled concurrently over multiple narrowband channels. in this paper, we analyze proportional fair scheduling (pfs) in multi-carrier systems over a wideband frequency-selective channel. in particular, we first derive analytical expressions for the throughput of opportunistic scheduling under proportional fairness constraints in a frequency-selective channel, for both single-user and multi-user systems. furthermore, we provide closed-form expression to quantify the throughput benefit of the multi-user pfs over the single-user pfs in frequency-selective systems. this research is an extension of our previous theoretical work on opportunistic scheduling over flat-fading channel in narrowband single-carrier systems.
slow adaptive ofdma via stochastic programming. fueled by the promises of high spectral efficiency, adaptive ofdma has attracted enormous research interests over the last decade. the significant capacity gain of adaptive ofdma comes from fast adaptation of resource allocation in response to instantaneous channel conditions. despite years of efforts to improve the practicality of adaptive ofdma, such promising technique is still far from real implementation due to the prohibitively high computational complexity and excessive control overhead. this paper is an endeavor to address the problem by proposing a slow adaptation scheme, where resource allocation is adapted on a much slower time scale than the fluctuation of wireless channel fading. specifically, the slow adaptive ofdma is formulated into a stochastic programming problem, which adapts resource allocation according to the channel statistics within an adaptation window rather than according to instantaneous channel conditions. by tuning the length of the adaptation window, we could engineer a desirable tradeoff between spectral efficiency and computational complexity. furthermore, the proposed scheme can be modified to accommodate inelastic traffics. the modification, referred to as "safe" slow adaptation, ensures worst-case data rates to all users. in this work, safe slow adaptation is formulated into a conic linear program, which is efficiently solved via interior-point methods. through extensive simulations, we show that the proposed schemes drastically reduce the computational complexity and control overheads, while achieving satisfactorily high spectral efficiency and qos provisioning as their fast-adaptation counterpart does with a much higher cost.
level biased random walk for information discovery in wireless sensor networks. in this paper, we consider the problem of information discovery in wireless sensor networks (wsns), where the search initiator is unaware of any of the γ locations of target information. one of the fundamental techniques which is used for this purpose is random walk since it has several advantages like low cost (number of bytes transmitted) compared to flooding, load balancing among nodes, and minimal state maintenance. even though random walk reduces cost, it is still high enough for energy constrained networks like wsns. furthermore, random walk incurs high latencies making it infeasible for delay sensitive applications. to alleviate the above mentioned problems in random walk, we propose a variant of random walk called level biased random walk (lbrw). in lbrw, the search packet traverses from the sink node (search initiator) to the circumference nodes (nodes without children) of the network and vice versa via random paths. the idea is to improve the node coverage of lbrw compared to that of random walk by forcing it to move in some particular directions. we show by extensive simulations that the cost and latency of lbrw are only 56-69% of that by random walk, when γ = 3 and at reasonable densities.
a graph approach to dynamic fractional frequency reuse (ffr) in multi-cell ofdma networks. a graph-based framework for dynamic fractional frequency reuse (ffr) in multi-cell ofdma networks is proposed in this work. ffr is a promising resource allocation technique that can effectively mitigate inter-cell interference (ici) in ofdma networks. the proposed scheme enhances the conventional ffr by enabling adaptive spectral sharing per cell load conditions. such adaptation has significant benefits in a practical environment where traffic load in different cells may be asymmetric and time-varying. the dynamic feature is accomplished via a graph approach in which the resource allocation problem is translated to a graph coloring problem. specifically, in order to incorporate various versions of ffr in our framework, we construct a graph that matches the specific version of ffr and then color the graph using the corresponding graph algorithm. the performance improvement enabled by the proposed dynamic ffr scheme is further demonstrated by computer simulation for a 19-cell network with asymmetric cell load. for instance, the proposed dynamic ffr scheme can achieve a 12% and 33% gain in cell throughput and service rate over conventional ffr, and render a 70% and 107% gain in cell throughput and service rate with respect to the reuse-3 system.
a modified exclusion mechanism and optimal routing algorithm in uwb networks. ultra-wide band (uwb) is a radio technology that uses a very large bandwidth. a two-dimensional exclusion mechanism and routing strategy are mentioned in [1]. we extend the exclusion region to three-dimension and modify the interference from other nodes as gaussian noise. the conclusion is also correct under mobility. we also present a new model combining exclusion mechanism and interference mitigation. then we propose an optimal routing algorithm described as mti. we raise a geometrical method unlike the simulation in [1] to demonstrate that the mer routing minimize the total interference and is the optimal routing.
wireless sensor networks localization with isomap. this paper studies the problem of determining the sensors' locations in wireless sensor networks. to alleviate the influence of the noise and the inaccurate measurement in the complicated environment, rather than estimating the pairwise euclidean distance between sensors, we use the geodesic distance to measure the dissimilarity between sensors, and employ the isomap algorithm to determine the relative locations of sensors. given sufficient anchors, the relative locations can be aligned to absolute locations by using coordinate transformation. the coordinate transformation matrix can be obtained by minimizing the sum of squares of the errors between the true locations of the anchors and their transformed locations. since isomap is parameter-sensitive, we also present an adaptive parameter selection procedure based on the locations of anchors. simulation results show that the isomap algorithm achieves smaller average location error with little quantity of anchors.
a directional broadcast protocol for emergency message exchange in inter-vehicle communications. broadcast is an effective approach for safety-related information exchange to achieve cooperative driving in vehicular ad hoc network (vanet). however, it suffers from several fundamental challenges such as message redundancy, link unreliability, hidden terminal and broadcast storm, etc., which degrade the efficiency of the network greatly. to address these issues, this paper proposes a position based multi-hop broadcast protocol (pmbp) for emergency message dissemination in inter-vehicle communications. by adopting a cross-layer approach considering both the mac and network layers in the proposed scheme, the candidate vehicle for forwarding an emergency message is selected according to its distance from the source vehicle in the message propagation direction. analysis and simulation results show that pmbp can not only quickly deliver emergency messages, but also reduce broadcast message redundancy significantly.
dynamic policy based model for trust based access control in p2p applications. dynamic self-organizing groups like wikipedia, and f/oss have special security requirements not addressed by typical access control mechanisms. an example is the ability to collaboratively modify access control policies based on the evolution of the group and trust and behavior levels. in this paper we propose a new framework for dynamic multi-level access control policies based on trust and reputation. the framework has interesting features wherein the group can switch between policies over time, influenced by the system's state or environment. based on the behavior and trust level of peers in the group and the current group composition, it is possible for peers to collaboratively modify policies such as join, update and job allocation. we have modeled the framework using the declarative language prolog. we also performed some simulations to illustrate the features of our framework.
authentication tests based on test type matrix. the theory of authentication tests is a powerful tool for analyzing and designing cryptographic protocols. however, it is difficult to apply the theory directly to prove the security goals of the protocols because determining the type of the test (e.g. outgoing, incoming and unsolicited test) is a little complex for computer and deriving the security properties of a test needs more intelligence. therefore, automatic security protocol analyzer cannot be implemented efficiently based on this theory. to solve this problem, in this paper we propose an authentication test type matrix (attm), which makes the identification of the test type very simple and straightforward. furthermore, we propose and prove a set of security properties associated with each case indicated by the elements in the attm, which can be used directly in protocol analysis and design. using the example of needham-schroeder protocol, we demonstrate that attm makes automatic security protocol verification and design much easier and more straightforward.
picocells with mimo and cell bonding for wlan systems. we consider a picocell system that implements multiple input multiple output (mimo) using cell bonding with one antenna per node. we show that this picocell system can initially have 1/2 or fewer access points (aps) with similar voice over ip coverage as a conventional system, yet can gracefully grow to the capacity of conventional systems with the same number of aps. although the coverage is somewhat lower for mimo (both 2×2 and 4×4), we show that through the use of dynamic antenna/node selection the picocell system with cell bonding can have similar coverage to conventional systems.
spectogram reconstruction from random sampling: application to the gsm band sensing. in the context of cognitive radios, we present a method to sense wideband radio spectra from randomly distributed samples with an average sampling rate smaller than the nyquist sampling rate. the method finds its roots in the compressed sensing paradigm. the gabor time-frequency is employed as a sparsifying transform to represent the radio signals generated in the framework of tdma/fdma based radio access technologies. indeed, many white spaces are observable in these wideband spectrograms. in addition, noisy measurements are modeled through the basis pursuit denoise formulation, which enables to reconstruct the time-frequency representation with some errors or information losses. the method is experimented on measured baseband radio signals sampled at 51.2mhz and acquired in the gsm 900 downlink band. finally, results about the effects of the algorithm parameters and about the algorithm complexity are provided and discussed.
an adaptive peer selection scheme with dynamic network condition awareness. locality-based peer selection paradigms have been proposed recently based on cooperation between peer-to-peer (p2p) service providers, internet service providers (isps) and end users in order to achieve efficient resource utilization by p2p traffic. based on this cooperation between different stakeholders, we introduce a more advanced paradigm with adaptive peer selection that takes into account traffic dynamics in the operational network. specifically, peers associated with low path utilization as measured by the isp are selected in order to reduce the probability of network congestion. this approach not only improves real-time p2p service assurance but also optimizes the overall use of network resources. our simulations based on the geant network topology and real traffic traces show that the proposed adaptive peer selection scheme achieves significant improvement in utilizing bandwidth resources as compared to static locality-based approaches.
towards a taxonomy of wired and wireless anonymous networks. with the aim to preserve privacy over a communications network, a plethora of anonymous protocols have been proposed along with many empirical investigations into specific adversary attacks over those networks. however, no known taxonomies exist that address anonymity in the diverse set of both wired and wireless anonymous communications networks. this paper proposes such a novel cubic taxonomy which explores the three key components of anonymity property, adversary capability, and network type. this taxonomy expands the definition of anonymity and aids in the advancement of state-of-the-art technological privacy-preserving mechanisms in anonymous networks against any adversary.
achieving exponential diversity in wireless multihop systems with regenerative relays. we present and analyze two different power allocation strategies for considerably improving the average bit error rate (ber) performance of wireless multihop systems with an arbitrary number of regenerative relay stations. in both cases, the power allocation is done based on instantaneous channel state information subject to an overall sum power constraint as well as possible additional per-node power constraints and it is optimal in terms of minimizing an upper bound on the average end-to-end ber. it is shown that for a general class of fading distributions with both schemes exponential diversity can be achieved and we express the corresponding upper bounds on the average ber in closed-form for the important case of nakagami-m fading on all hops. finally, the performance of our approach is illustrated and evaluated by means of both numerical and simulation results.