nils-herrmann/clean_scirepeval huggingface dataset:
An optimal dynamic pricing framework for autonomous mobile ad hoc networks

In autonomous mobile ad hoc networks (MANET) where each user is its own authority, fully cooperative behaviors, such as unconditionally forwarding packets for each other, cannot be directly assumed. The pricing mechanism is one way to provide incentives for the users to act cooperatively by rewarding some payment for cooperative behaviors. Here, we model the pricing and routing in autonomous MANETs as multi-stage dynamic games. A dynamic pricing framework is proposed to maximize the sender/receiver's payoff by considering the dynamic nature of MANETs. Meanwhile, the forwarding incentives of the relay nodes can also be maintained by providing the optimal payments based on the auction rules. The simulation results illustrate that the proposed dynamic pricing schemes have significant performance gains over the existing static pricing algorithms.
Space-time signal design for time-correlated Rayleigh fading channels

The existing construction of space-time codes or modulation has mainly focused on two ideal situations: either quasi-static or rapid fading channels. In this paper, we consider the design of robust space-time modulation for time-correlated Rayleigh fading channels. We show that the space-time signals of square size achieving full diversity in quasi-static fading channels can also achieve the full diversity in time-correlated fading channels irrespectively of the time correlation matrix. Moreover, we propose a space-time signal construction method by combining orthogonal designs with sphere packings. The simulation results show that our scheme outperforms the previously existing methods. For example, we observe a coding gain of about 1.5 dB over the conventional orthogonal design, about 2 dB over the parametric code, and about 4 dB over the cyclic code under certain fading conditions.
An adaptive interpolation scheme for 2-D mesh motion compensation

Two dimensional mesh motion compensation produces blocking free prediction in contrast to block matching motion compensation by generating a smooth full motion field from the set of node motion vectors. This is clearly not appropriate across moving object boundaries where motion discontinuities exist. In this paper, we address this problem by proposing an adaptive interpolation scheme for patches that contain multiple motions (i.e., patches around motion boundaries). Simulation results show improvements over standard 2-D mesh motion compensation at a fraction of computational increase.
An efficient timing model for hardware implementation of multirate dataflow graphs

We consider the problem of representing timing information associated with functions in a dataflow graph used to represent a signal processing system in the context of high-level hardware (architectural) synthesis. This information is used for synthesis of appropriate architectures for implementing the graph. Conventional models for timing suffer from shortcomings that make it difficult to represent timing information in a hierarchical manner, especially for multirate signal processing systems. We identify some of these shortcomings, and provide an alternate model that does not have these problems. We show that with some reasonable assumptions on the way hardware implementations of multirate systems operate, we can derive general hierarchical descriptions of multirate systems similarly to single rate systems. Several analytical results such as the computation of the iteration period bound, that previously applied only to single rate systems can also easily be extended to multirate systems under the new assumptions. We have applied our model to several multirate signal processing applications, and obtained favorable results. We present results of the timing information computed for several multirate DSP applications that show how the new treatment can streamline the problem of performance analysis and synthesis of such systems.
A fast tracking adaptive array system for mobile communications

In slowly time-varying fading channels, adaptive diversity combining can reduce multipath fading of desired signal and suppress interfering signals. However, for fast time-varying fading channels, there are no effective techniques to achieve the same results. The continued use of decision directed adaptive array algorithms on the fast fading channels will cause error propagation. This paper presents a novel adaptive diversity combining technique with proposed M-D decoder and QRD-RLS based parallel weights tracking. This system reduces error propagation in the decision directed array systems while maintaining the same tracking speed. Computer simulation has been performed to show the effectiveness and much better performance than that of the existing techniques.
Adaptive QoS for wireless multimedia networks using power control and smart antennas

This paper addresses the problem of adaptive quality-of-service (QoS) for mobile multimedia services under a power controlled wireless network using smart antennas. Given the nature of multimedia, we chose the signal-to-interference-and-noise ratio (SINR) of each user's channel as the QoS index. We direct our attention toward two problems. The first is to increase the SINR levels for multimedia users as much as the system can provide for, under channel fading and interference conditions. Different users have distinct desired SINR levels according to their requested service types; our algorithm uses an iterative method to drive the SINR levels as close as possible to those desired levels. The SINR levels are improved without deteriorating quality for other types of users. Simulations show a significant increase in the average SINR levels for multimedia users. The second problem considered is how to initiate new users into the network speedily by using lower complexity algorithms that yield reliable results. Simulations show that our fast activation scheme can substantially reduce the time for activating new users into the system.
A trust evaluation framework in distributed networks: Vulnerability analysis and defense against attacks

The performance of distributed networks depends on collaboration among distributed entities. To enhance security in distributed networks, such as ad hoc networks, it is important to evaluate the trustworthiness of participating entities since trust is the major driving force for collaboration. In this paper, we present a framework to quantitatively measure trust, model trust propagation, and defend trust evaluation systems against malicious attacks. In particular, we address the fundamental understanding of trust, quantitative trust metrics, mathematical properties of trust, dynamic properties of trust, and trust models. The attacks against trust evaluation are identified and defense techniques are developed. The proposed trust evaluation system is employed in ad hoc networks for securing ad hoc routing and assisting malicious node detection. The implementation is fully distributed. Simulations show that the proposed system can significantly improve network throughput as well as effectively detect malicious behaviors in ad hoc networks. Further, extensive simulations are performed to illustrate various attacks and the effectiveness of the proposed defense techniques.
Distributed state estimation with lossy measurement compression in smart grid

State estimation in smart grid highly relies on the availability of measurements. Due to the interconnected nature of the power grid, the measurements at different substations are not totally independent and thus contain some redundancy. Among the various environments the power grid work in, there are certain circumstances the system communication capability is limited such that transmitting a lot of measurements within a small time interval is expensive and sometimes even impossible, and thus the measurements need to be compressed before transmitted to remove the redundancy. While it is possible to design lossless compression methods in some cases, in this paper, we focus on the problem of lossy compression of the measurements to adapt to more severe conditions. An algorithm is proposed to jointly design the pre-processors that compressing the measurements subject to the communication constraints and the subsequent estimator that using only the compressed measurements for state estimation. The effectiveness of the proposed algorithm is illustrated by numerical results.
Multinode Cooperative Communications in Wireless Networks

In this paper, a class of cooperative communication protocols with arbitrary N-relay nodes is proposed for wireless networks, in which each relay coherently combines the signals received from m (1lesmlesN-1) previous relays in addition to the signal from the source. Exact symbol-error-rate (SER) expressions for an arbitrary N-node network employing M'ary phase-shift-keying (MPSK) modulation or quadrature-amplitude modulation (QAM) are provided for the proposed class of protocols. Further, approximate expressions for the SER are derived and shown to be tight at high enough signal-to-noise ratio (SNR). Our analysis reveals an interesting result: The class of cooperative protocols shares the same asymptotic performance at high enough SNR and does not depend on m, the number of previous nodes involving in coherent detection, hence, the asymptotic performance of a simple cooperative scenario in which each relay combines the signals from the source and the previous relay is exactly the same as that for a much more complicated scenario in which each relay combines the signals from the source and all the previous relays. The theoretical results also confirm that full diversity equal to the number of cooperating nodes is indeed achievable by the proposed protocols. Finally, we formulate a power-allocation problem in order to minimize the SER of the system. The analysis shows that the optimum power allocation at different nodes follows a certain ordering, and that the power-allocation scheme at high SNR does not depend on the channel quality of the direct link between the source and the destination. Closed-form solutions for the optimal power-allocation problem are provided for some network topologies. Simulation results confirm our theoretical analysis
Power minimization under throughput management over wireless networks with antenna diversity

In multiaccess wireless communication systems, power control and adaptive modulation are two important means to increase spectral efficiencies, combat time-varying fading channels, and reduce cochannel interferences. The overall uplink transmitted power is minimized under the constraints that there is no reduction in overall network throughput and each user achieves the desired time-average throughput. Adaptive M-QAM modulations with two kinds of antenna diversity are considered. Each user can select a range of modulation rates, according to his channel condition and transmission history. Two subproblems are considered for the development of suboptimal low-complexity adaptive algorithms. First, at the user level, the following needs to be determined: the range of modulation rates that each user can accept at a specific time to ensure fairness. Then, each time at the system level, within the acceptable ranges, the system finds out what throughput allocation for different users requires the lowest overall transmitted power. The scheme can be interpreted as "water filling" each user's throughput in time domain and allocating network throughput to different users at each time. From the simulation results, the proposed scheme reduces the overall transmitted power up to 7 dB and increases average spectral efficiency up to 1.2 bit/s/Hz, compared with the previous known power control schemes.
Cognitive multiple access via cooperation: Protocol design and performance analysis

In this paper, a novel cognitive multiple-access strategy in the presence of a cooperating relay is proposed. Exploiting an important phenomenon in wireless networks, source burstiness, the cognitive relay utilizes the periods of silence of the terminals to enable cooperation. Therefore, no extra channel resources are allocated for cooperation and the system encounters no bandwidth losses. Two protocols are developed to implement the proposed multiple-access strategy. The maximum stable throughput region and the delay performance of the proposed protocols are characterized. The results reveal that the proposed protocols provide significant performance gains over conventional relaying strategies such as selection and incremental relaying, specially at high spectral efficiency regimes. The rationale is that the lossless bandwidth property of the proposed protocols results in a graceful degradation in the maximum stable throughput with increasing the required rate of communication. On the other hand, conventional relaying strategies suffer from catastrophic performance degradation because of their inherent bandwidth inefficiency that results from allocating specific channel resources for cooperation at the relay. The analysis reveals that the throughput region of the proposed strategy is a subset of its maximum stable throughput region, which is different from random access, where both regions are conjectured to be identical.
Energy-efficient resource allocation for multiband UWB communication systems

The emerging ultra-wideband (UWB) system offers a great potential for the design of high-speed short-range communications. However, UWB faces a significant challenge in achieving a low transmit power level, while assuring an adequate system performance. An efficient management of the limited power is thus a key feature to fully exploit the advantages of UWB. In this paper, a cross layer multiuser multiband UWB scheme is proposed to obtain the optimal subband and power allocation strategy. Optimization criteria involve minimization of power consumption under the constraints on the packet error rate, transmission rate, and FCC regulations. To reduce the problem complexity, which is found to be NP hard a computationally inexpensive suboptimal approach is developed. Simulation results under UWB channel model specified in the IEEE 802.15.3a standard show that the proposed algorithm achieves comparable performance to that of the complex optimal full search approach, and it can save up to 61% of transmit power compared to the multiband scheme in the standard proposal.
Traffic improvements in wireless communication networks using antenna arrays

A wireless network with beamforming capabilities at the receiver is considered that allows two or more transmitters to share the same channel to communicate with the base station. A novel approach is introduced, which combines the effects of the digital signal processing (adaptive beamforming) at the physical layer with the traffic policies at the network layer on the overall queuing model of a cell. The effect of signal processing on the queuing model of the cell is represented by a parameter in the final cell model. Each cell is modeled by a multiuser/multiserver service facility, where each server is a beamformed channel formed by the cell's base station. From this effective cell model, we find the closed form solutions for blocking probabilities of the calls and total carried traffic in a wireless network with adaptive arrays. Our analytical as well as numerical results show that adaptive beamforming at the receiver reduces the blocking probability of the calls and increases the total carried traffic in the system.
Generalized anti-eavesdropping space-time network coding for cooperative communications

Physical (PHY) layer security has recently become a hot issue in wireless communication. In this paper, an approach to a generalized anti-eavesdropping space-time network coding (GAE-STNC) for cooperative communications is proposed to achieve the physical layer security and overcome the problem of imperfect synchronization while still guaranteeing full diversity. Based on the assumption of channel reciprocity, the basic idea is to exploit the channel state information (CSI) between the legitimate transmitters and the receiver, which is used to generate the secret key. With this secret key, the transmitters introduce pseudo random interferences by adding an anti-eavesdropping matrix to the initial system. Since the eavesdropper's channel is typically independent of the legitimate channel, the channel between the legitimate transmitters-receiver pair, the signal received by the eavesdropper is interfered. While the receiver can effectively decode the signal by utilizing the global CSI, the eavesdroppers can not decode the received signal correctly. Then, two specific schemes derived from the GAE-STNC are proposed. Numerical analysis and simulation results are presented to illustrate the proposed GAE-STNC schemes.
Distributive Opportunistic Spectrum Access for Cognitive Radio using Correlated Equilibrium and No-Regret Learning

Cognitive radio has been proposed as a novel approach for improving the utilization of the precious limited radio resources by dynamically accessing the spectrum. One of the major design challenges is to coordinate and cooperate in accessing the spectrum opportunistically among multiple distributive users with only local information. In this paper, we propose a game theoretical approach with a new solution concept, the correlated equilibrium, which is better compared to the non-cooperative Nash equilibrium in terms of spectrum utilization efficiency and fairness among the distributive users. To achieve this correlated equilibrium, we construct an adaptive algorithm based on no-regret learning that guarantees convergence. From the simulation results, the optimal correlated equilibria achieve better fairness and 5% ~15% performance gain, compared to the Nash equilibria.
On the robustness of space-time coding techniques based on a general space-time covariance model

The robustness of space-time coding techniques for wireless channels that exhibit both temporal and spatial correlation is investigated. A general space-time covariance model is developed and employed to evaluate the exact pairwise error probability for space-time block codes. The expressions developed for the pairwise error probability are used in conjunction with the union bound to determine an upper bound for the probability of a block error. The block error probability is evaluated for several space-time codes and for wireless channels that exhibit varying degrees of spatial and temporal correlation. Numerical results are presented for a two-dimensional Gaussian scatterer model which has been shown to be consistent with recent field measurements of wireless channels. The results demonstrate that the best-case wireless channel is uncorrelated in both space and time. Correlation between transmission paths, due to insufficient spacing of the transmit antennas or scatterers located in close proximity to the mobile, can result in a significant performance degradation. The conditions that result in uncorrelated transmission paths are quantified in terms of the effective scattering radius and the spacing of the transmit and receive antennas.
SER performance analysis and optimum power allocation for decode-and-forward cooperation protocol in wireless networks

We derive a closed-form symbol-error-rate (SER) formulation for the cooperation system with PSK and QAM signals. Moreover, two SER upper bounds are established to show the asymptotic performance of the cooperation protocol, in which one of them is tight at a high signal-to-noise ratio. Based on the SER performance analysis, we also determine the optimum power allocation for the cooperation systems. It turns out that an equal power strategy is, in general, not optimum in cooperation communications, and the optimum power allocation depends on the channel link quality. An interesting result is that, in the case that all channel links are available, the optimum power allocation does not depend on the direct link between source and destination, it depends only on the channel links related to the relay. Extensive simulations are performed to validate the theoretical results.
Power minimization under constant throughput constraint in wireless networks with beamforming

In multi-access wireless communication systems, power control and adaptive modulation are two important means to increase spectral efficiency, combat with time varying fading environments, and reduce cochannel interference. The overall transmitted power is minimized by using adaptive MQAM modulation. Each link can select a different MQAM modulation range according to its current channel condition. Each link's time average throughput is constant. The overall network throughput is constant to ensure the network performance. The scheme can be interpreted as "water filling" each link's throughput in the time domain and allocating overall throughput to different links at each time. From the simulation results, our schemes reduce up to 80% overall transmitted power at BER=10/sup -3/, 66% overall transmitted power at BER=10/sup -6/, and increase average spectral efficiency by about 1.2 bit/s/Hz.
On Energy Harvesting Gain and Diversity Analysis in Cooperative Communications

The use of energy harvesting cooperative relays is a promising solution to battery-limited wireless networks. In this paper, we consider a cooperative system in which one source node transmits data to one destination with the assistance of an energy harvesting decode-and-forward (DF) relay node. Our objective is to minimize the long-term average symbol error rate (SER) performance through a Markov decision process (MDP) framework. By doing so, we find the optimal stochastic power control at the relay that adapts the transmission power to the changes of energy harvesting, battery, channel, and decoding states. We derive a finite-integral expression for the exact average SER of the cooperative system. Further insights are gained by analyzing the asymptotic average SER and its lower and upper bounds at high signal-to-noise ratio (SNR), and the performance is eventually characterized by the occurrence probability of the relay's actions at the worst channel states in the MDP. We also show that the optimal cooperative policy at asymptotically high SNR follows a threshold-type structure, i.e., the relay spends the harvested energy only when the signal is successfully decoded and the source is faced with the worst channel condition in its direct link. Using these observations to quantify the diversity gain and the energy harvesting gain, we reveal that full diversity is guaranteed if and only if the probability of harvesting zero energy quantum is zero, which can be achieved by reducing the energy quantum size or increasing the energy harvesting capability. Finally, we present several numerical examples to validate the analytical findings.
Behavior Forensics in Traitors within Traitors for Scalable Multimedia

A cost effective attack against multimedia forensics is the multiuser collusion attack, in which several attackers mount attacks collectively to remove traces of the identifying fingerprints and hinder traitor tracing. An important issue in collusion is to ensure that all colluders have the same probability of being detected. While they might agree so, some selfish colluders may wish to further lower their own risk of being caught. This paper investigates this problem of "traitors within traitors", in an effort to formulate the dynamics among attackers during collusion. We consider scalable multimedia forensic systems where users receive fingerprinted copies of different quality due to network and device heterogeneity, and explore the techniques that a selfish colluder can use to minimize his/her probability of being detected. Our results show that changing the resolution of their received copies before multi-user collusion can help selfish colluders further reduce their risk, especially when the colluded copy has high resolution.