waashk/dblp huggingface dataset:
a novel graph model for dynamic multicast flow aggregation in optical networks. in this paper, we address the dynamic multicast flow aggregation problem and propose a novel graph model with different aggregation policies. we first give the network model with an auxiliary graph for the aggregation. we then discuss an aggregation algorithm using the auxiliary graph and propose three policies for aggregating multicast flows. numerical results show that aggregation can tremendously reduce the total trees in the network while the three policies can achieve good performance for various scenarios.
service cluster: a new framework for sla-oriented provisioning in wdm mesh networks. a service level agreement (sla) typically specifies the availability a service provider (sp) promises to a customer. current schemes usually employ backup resources to achieve high sla satisfaction. we propose a new provisioning framework, called service cluster (sc), which uses no explicit backup resources. by grouping several services with (typically) different availability specifications, an sc can dynamically reallocate resources to avoid sla violations. services that can tolerate additional down time lend resources to services that need to be kept running. we first analyze a condition for admission control. we then propose a dynamic resource allocation scheme (adt1 balancing scheme, sc-abs) and apply it to the sc framework. the dynamic management of sc-abs is realized by novel sla-violation estimation in an event-driven manner without continuous monitoring. we compare sc-abs with shared-path protection, and numerically show its various advantages in terms of: 1) higher sla satisfaction (up to 30% more); 2) lower service blocking ratio; 3) higher tolerance of failures; 4) more balanced sla satisfaction; and 5) consuming no explicit backup (or standby) resources. our scheme can meet the sla of significantly more services than protection-based schemes, thus providing more profit for the sp and lower cost for the customer.
designing demand-wise shared protection networks with specified minimum dual-failure restorability. we develop a new integer linear programming model to optimally design demand-wise shared protection (dsp) networks to achieve specified minimum levels of dual-failure restorability at minimum cost. findings suggest that dual-failure restorability levels of up to 40% can be achieved with minimal additional capacity relative to single-failure restorable designs. network designs approaching full dual-failure restorability require substantially greater amounts of spare capacity.
backbone construction for heterogeneous wireless ad hoc networks. in this paper, we propose a backbone construction scheme over heterogeneous ad hoc networks, where the network nodes have different characteristics such as communication capacity, processing power and energy resource. most of the wireless backbone construction techniques focus on minimizing the number of backbone nodes. in our proposed scheme, we not only minimize the backbone size, but also take the characteristics of nodes into account when building a backbone. in the scheme, the more capable nodes have higher probability to serve as backbone nodes and provide a wireless highway over which end-to-end communication can take place. the proposed scheme includes two major steps, which can be solved by formulating as a dominating set (ds) problem and a steiner tree problem with minimum number of steiner points (stp-msp) respectively. we focus on the two subproblems and present a number of polynomial time approximation algorithms. simulation results show that the proposed scheme achieves higher average backbone node performance, while has approximately the same backbone size comparing with other schemes.
model-tree-based rate adaptation scheme for vehicular networks. rate adaptation techniques have been extensively studied for traditional wireless lans as way to adjust the data transmission bandwidth as a function of the channel quality. however, existing solutions which are mostly based on statistics collection inherently experience a large delay in response to the wireless channel fluctuations, which is unsuitable for the rapid changing of the channel conditions in vehicular networks. in this paper, we propose an efficient self-adaptive model-tree-based rate adaptation scheme termed mtra that can predict the packet error rate (per) and adapt the data rate in real time. we also present a detailed methodology for the per model tree building and update. we have performed comprehensive experimentations using ns-2 simulations which demonstrate that mtra can achieve much better performance than the traditional rate adaptation approaches under various scenarios in vehicular networks.
an iterative list-based multiuser detector for overloaded receivers in a rayleigh fading channel. we consider a wireless communication system where multiple co-channel users transmit data via a synchronous, frequency-flat rayleigh fading channel. the receiver employs an antenna array. the paper develops an iterative list multiuser detector for overloaded applications where the number of transmitted signals exceeds the number of receive antennas. the receiver uses a linear preprocessor to reduce co-channel interference followed by a multiuser detector with an iterative groupwise symbol detection algorithm that extracts a list of the most likely user symbols. simulation results show that the proposed detector provides good complexity-performance trade offs.
on the performance improvements of max-sinr equalizers in wireless communications. in this work, we derive a blind equalizer that pursues the maximization of an objective function, consisting of the ratio between the square of the mean signal power and the variance of the signal power. the performance of the addressed equalizers is then investigated by focusing on ds/cdma communication environments in a downlink scenario. in particular, we have evidenced the effectiveness of the presented equalizer in the numerical examples, in terms of robustness against the effect of interference, as well as in terms of convergence rate, in spite of a small amount of extra processing
symbol based search space constraining for complexity/performance scalable near ml detection in spatial multiplexing mimo ofdm systems. for both outdoor and indoor wireless systems there is an increasing demand of high spectral efficiency at a very low cost and power consumption. in this context, mimo wireless system adopting spatial multiplexing offer a way of increasing the spectral efficiency of the system. in order to fully exploit this capacity non linear mimo detectors such as maximum likelihood detectors are required. however, when high order modulation schemes are applied, the complexity of this kind of detector becomes prohibitive for a practical implementation. as a solution to this problem, low complexity maximum likelihood detectors such as sphere detectors are appealing as a low complexity solution for high spectral efficiency transmission. although sphere decoding provides a lower complexity solution than a classical ml detector, its complexity still remains unpredictable and exponentially dependent on channel propagation conditions. this variability in complexity makes the implementation of sphere decoders not practical. in this paper, a new approach for constraining the ml search space is proposed which provides a predictable upper bound for complexity, hence facilitating its implementation. moreover, the new approach for computing the constrained search space significantly reduces the complexity of the detection while offering scalability in terms of performance and complexity. simulation results in a cellular system demonstrate the scalability of our detector and the performance/complexity trade-off that it enables.
joint effect of multiple correlated cameras in wireless multimedia sensor networks. wireless multimedia sensor networks (wmsns) are interconnected devices that allow retrieving video and audio streams, still images, and scalar data from the environment. in a densely deployed wmsn, there exists correlation among the visual information observed by cameras with overlapped field of views. in this paper, the correlation characteristics of visual information are used to address two issues: 1) how to measure the amount of visual information provided by multiple cameras in the network, and 2) how to select a group of cameras to report their information to the sink under distortion constraints. an entropy-based analytical framework is developed to measure the amount of visual information provided by multiple correlated cameras first. based on this framework, a correlation-based camera selection scheme is introduced. simulation results show that, given a distortion bound at the sink, the correlation-based selection scheme requires fewer cameras to report to the sink than the random selection scheme.
approximation algorithm for qos routing with multiple additive constraints. in this paper, we study the problem of computing the supported qos from a source to a destination with multiple additive constraints. the problem has been shown to be np-complete and many approximation algorithms have been developed. we propose a new approximation algorithm called multi-dimensional relaxation algorithm. we formally prove that our algorithm produces smaller approximation error than the existing algorithms. we further verify the performance by extensive simulations.
design and implementation of physical layer private key setting for wireless networks. due to the enormous spreading of applied wireless networks, security is actually one of the most important issues for telecommunications. one of the main issue in the field of securing wireless information exchanging is the initial common knowledge between source and destination. a shared secret is normally mandatory in order to decide the encryption (algorithm or code or key) of the information stream. it is usual to exchange this common a priori knowledge by using a "secure" channel. now a days a secure wireless channel is not possible. in fact normally the common a priori knowledge is already established (but this is not secure) or by using a non-radio channel (that implies a waste of time and resource). this contribution deals with the proposal of a new modulation technique ensuring secure communication in a full wireless environment. the information is modulated, at physical layer, by the thermal noise experienced by the link between two terminals. a loop scheme is designed for unique recovering of mutual information. the probability of error/detection is analytically derived for the legal users and for the third unwanted listener. the proposed scheme has also been implemented in a xilinx virtex ii fpga. all the results show that the performance of the proposed scheme yields the advantage of intrinsic security, i.e., the mutual information cannot be physically demodulated (passive attack) or denied (active attack) by a third terminal, leading us to conclude that the proposed technique is really useful for private key distribution in every wireless network.
distributed communication control mechanisms for ad hoc networks. we considered a single hop ad-hoc network consisting of n source-destination pairs. each transmitter is endowed with a finite buffer and accepts packets from a poisson distributed arrival process. the channel is described by a markov chain. we investigate distributed algorithms for joint admission control, rate and power allocation aiming at maximizing the individual or the global throughput defined as the average information rate successfully received. the decisions are based on the statistical knowledge of the channel and buffer states of the other communication pairs and on the exact knowledge of their own channel and buffer states. the problems are formulated as a cooperative and noncooperative games and reduced to the mathematical framework of the variational inequalities problems. the proposed algorithms provide sizable improvements with respect to straightforward extension of decentralized algorithms for multiple access channels to ad hoc networks.
optimal weighted antenna selection for imperfect channel knowledge from training. receive antenna selection (as) reduces the hardware complexity of multi-antenna receivers by dynamically connecting an instantaneously best antenna element to the available radio frequency (rf) chain. due to the hardware constraints, the channels at various antenna elements have to be sounded sequentially to obtain estimates that are required for selecting the "best" antenna and for coherently demodulating data. consequently, the channel state information at different antennas is outdated by different amounts. we show that, for this reason, simply selecting the antenna with the highest estimated channel gain is not optimum. rather, the channel estimates of different antennas should be weighted differently, depending on the training scheme. we derive closed-form expressions for the symbol error probability (sep) of as for mpsk and mqam in time-varying rayleigh fading channels for arbitrary selection weights, and validate them with simulations. we then derive an explicit formula for the optimal selection weights that minimize the sep. we find that when selection weights are not used, the sep need not improve as the number of antenna elements increases, which is in contrast to the ideal channel estimation case. however, the optimal selection weights remedy this situation and significantly improve performance.
joint reduction of peak to average power ratio and symbol loss rate in multicarrier systems. peak to average power ratio (papr) and symbol loss rate (slr) are two challenges of multicarrier based communications that have recently drawn much attention. high slr renders the system unreliable and high papr is associated with power inefficiency and nonlinearity of the system. there are rich literatures studying these two issues separately but, unfortunately, only a few works have studied simultaneous reductions of papr and slr. this paper studies the problem of reducing the papr while keeping the slr at minimum. in [1], we derived the conditions for the minimum slr in on-off channels. the algorithm proposed in this paper simultaneously satisfies the conditions derived in [1] and reduces the papr substantially. this paper differs from previous techniques in the sense that none of the previously proposed techniques are capable of reducing papr substantially while achieving the minimum symbol loss rate. we compare our algorithm with the optimum selected mapping papr reduction method, which is well known in the literature for having a strong reduction capability. the comparison is done in terms of complementary cumulative distribution function (ccdf) of the papr of the multicarrier signal. the simulation results show that our algorithm can achieve a stronger papr reduction while maintaining the minimum slr.
rate and power adaptation for increasing spectrum efficiency in cognitive radio networks. we propose rate and power adaptation strategies to optimize data transmission over fading channels in a spectrum sharing system operating under average received-interference constraint at the licensed user (primary user). specifically, considering availability of the channel state information (csi) pertaining to the secondary link and spectrum-sensing information about the activity state of the primary user, we investigate two adaptation policies at the secondary user's transmitter, namely, variable power and variable rate and power, over rayleigh fading channels. the adaptation policies are obtained by maximizing the achievable capacity under said constraint and bit error rate (ber) requirements in multilevel quadrature amplitude modulation (m-qam). we asses the benefits of using soft-sensing information about the primary user's activity on rate and power adaptation in spectrum sharing systems, and provide numerical results and comparisons illustrating performance for different operating scenarios.
low complexity antenna selection scheme for multiuser mimo broadcast systems. in this paper, a low complexity antenna selection scheme for multi-antenna broadcast systems is developed. using sum-rate capacity maximisation as the selection criteria, the proposed scheme exploits the duality principle of broadcast and multiple access channel in order to reduce the computational complexity. the performance of the proposed scheme under i.i.d. rayleigh fading channel is then evaluated via monte carlo simulation under different system parameters, and its performance is compared to the full complexity brute force scheme. it is demonstrated that the scheme is able to achieve most of the gain available in the system with a considerably lower complexity.
secure signaling in next generation networks with nsis. the ietf working group next steps in signaling (nsis) develops signaling protocols for quality-of-service (qos) reservations or dynamic nat and firewall (nat/fw) configuration. qos signaling allows for on-demand resource reservations in order to provide guaranteed quality-of-service for real-time oriented services in ip-based next generation networks whereas nat/fw signaling allows for establishing pinholes in firewalls or bindings in nat devices. qos signaling must be secured to allow for a reliable accounting and nat/fw configuration is a sensitive operation per se. this paper presents an approach that provides an integrity protection of nslp signaling messages by extending an nslp session authorization object. a worked example for secure qos signaling in a kerberos-secured domain is given.
a scalable block cipher design using filter banks and lifting over finite fields. a scalable block cipher based on a filter bank structure over gf(28) is proposed. the filter bank structure is used to introduce the diffusion during the circular convolution process between the filters coefficients (which are generated from the key) and the plaintext. the confusion is achieved by the mixing between the analysis filter bank and a novel lifting scheme. the proposed cipher is scalable in both block and key lengths. the cipher is shown to be secure against differential and linear cryptanalysis and of comparable complexity to the aes.
an energy-efficient integrated mac and routing protocol for wireless sensor networks. in recent integrated mac/routing solutions for wireless sensor networks (wsns), hop-count is exploited to build a coarse-grained logical coordinates to help forward packets towards the direction of sink. this method can retain the merits of geographic routing at the absence of exact location knowledge. however, these solutions may present low energy-efficiency and unacceptable delays in real networks since they seldom consider the impacts of low duty-cycling and link unreliability on routing. furthermore, geographic advancement of forwarding in hop-count based coordinates is very unreliable and even towards the reverse direction. in this work, average power cost to the sink of each node is considered together with hop-count to build a fine-grained logical coordinates, which can help forward packets towards the direction of sink more accurately. then we propose an energy-efficient integrated mac/routing (eemr) protocol for event-driven and time-critical applications based on new logical coordinates. the optimal relay is elected in each hop dynamically, where the objective is to optimize forwarding energy-efficiency on the premise that end-to-end delay is restricted under the predefined upper bound. analysis and extensive simulations are given to demonstrate the superiority of eemr by comparing its performance against existing solutions.
analysis, insights and generalization of a fast decentralized relay selection mechanism. relay selection for cooperative communications has attracted considerable research interest recently. while several criteria have been proposed for selecting one or more relays and analyzed, mechanisms that perform the selection in a distributed manner have received relatively less attention. in this paper, we analyze a splitting algorithm for selecting the single best relay amongst a known number of active nodes in a cooperative network. we develop new and exact asymptotic analysis for computing the average number of slots required to resolve the best relay. we then propose and analyze a new algorithm that addresses the general problem of selecting the best q ≥ 1 relays. regardless of the number of relays, the algorithm selects the best two relays within 4.406 slots and the best three within 6.491 slots, on average. our analysis also brings out an intimate relationship between multiple access selection and multiple access control algorithms.
loop-free forwarding table updates with minimal link overflow. the forwarding paths in an ip network may change due to a link failure, network equipment maintenance, or reconfiguration of link weights. the forwarding tables in the routers need then to be updated. these updates may cause transient loops and link overflow, if they are not performed in an appropriate order. while existing proposals achieve loop-free updates, transient link overflow is still a problem during the updating process. in this paper, we present a method that compares the initial and final forwarding paths, and obtains the updatable nodes that do not cause any transient loop or link overflow. however, this goal is not always achievable, therefore, we propose an algorithm to update the forwarding tables that will refrain the link overflows to a minimal level. the performance study on a real topology with two setups confirms that our approach achieves smaller link overflow than by using a previously proposed approach.
cognitive radio policy languages. this paper characterizes key issues in establishing a policy language for ieee standards activity p1900.5 to shape radio behavior that realizes social contracts and business logic via cognitive radio policy languages (crpl). this paper shows the current lack of consensus on the scope and needs of policy languages, tracing roots to differences among regulatory, financial, business, and technical domains. cognitive linguistics, an emerging theory of human language acquisition and use shows why this is the case and may assist in formulating a crpl that addresses the diverse policy needs of the regulatory and business communities as well as the narrower issues of dynamic spectrum.
performance analysis of double-channel 802.11n contending with single-channel 802.11. due to their ease of deployment, 802.11 networks are widely used. to cope with increasing throughput requirements, and to take advantage of improvements in hardware performance, 802.11n has been introduced. one of the extra features is the 20/40 functionality, which allows 802.11n devices to operate using one or two 802.11 channels. in this paper, we study the contention rules for such 20/40 operation on top of the 802.11 distributed coordination function (dcf). we then study the performance of double-channel users in presence of single-channel 802.11 users. similar to the 802.11 model introduced by bianchi, we introduce a markov model for both the legacy 802.11 and double-channel 802.11n users. to couple the markov models of both types of users, we have to understand how to relate virtual time slots of both types. next, we introduce collision rules that capture traditional in-channel 802.11 collisions as well as collisions between the different types of users. this allows us to complete the analytical throughput model for 802.11 and double-channel 802.11n users when they coexist. the conclusions are important for understanding 802.11 networks in particular, but also for contention of heterogeneous devices in general.