nils-herrmann/clean_scirepeval huggingface dataset:
An information theoretic framework for order of operations forensics

To verify the authenticity of easily manipulated multimedia content, forensic researchers have proposed many techniques to estimate the processing history of given multimedia content. When multiple operations may be applied on multimedia content, a complete processing history would involve the information of not only what manipulation operations have been applied, but also in what order they were applied. However, there are few works considering the problem of detecting the order of operations. Moreover, due to the interplay among operations, the order of operations may not always be detectable. This leads to a fundamental question of when we can or cannot detect the order of operations. In this paper, we propose an information theoretical framework to answer this question. Specifically, we formulate the problem of detecting the order of operations into a multiple hypotheses testing problem. Then, we propose an information theoretical framework to characterize the relationship between the true hypothesis and the detected hypothesis. Under this framework, we propose a mutual information based criterion to determine the detectability of the order of operations. Furthermore, conditional fingerprints are defined in this framework to understand why the order of operations is not always detectable. The detection of the order of resizing and blurring is examined in this paper, where the order detection scheme has been proposed and the effectiveness of our framework has been demonstrated by simulations.
Cooperative communications with relay-selection: when to cooperate and whom to cooperate with?

In this paper; we propose a new cooperative communication protocol, which achieves higher bandwidth efficiency while guaranteeing the same diversity order as that of the conventional cooperative schemes. The proposed scheme considers relay selection via the available partial channel state information (CSI) at the source and the relays. In particular, we discuss the multi-node decode-and-forward cooperative scenarios, where arbitrary N relays are available. The source determines when it needs to cooperate with one relay only, and which relay to cooperate with in case of cooperation, i.e., "When to cooperate?" and "Whom to cooperate with?". An optimal relay is the one which has the maximum instantaneous scaled harmonic mean functionof its source-relay and relay-destination channel gains. For the symmetric scenario, we derive an approximate expression of the bandwidth efficiency and obtain an upper bound on the symbol error rate (SER) performance. We show that full diversity is guaranteed and that a significant increase of the bandwidth efficiency is achieved. Moreover, we present the tradeoff between the achievable bandwidth efficiency and the corresponding SER. Finally, the obtained analytical results are verified through computer simulations.
Two-Way Denoise-and-Forward Relaying with Non-Coherent Differential Modulation

This work focuses on a two-way denoise-andforward relaying system using non-coherent Differential Binary Phase-Shift Keying (DBPSK) modulation. The relay denoising function and source decoders are designed using Maximum Likelihood (ML) principles. As the ML denoising function is hard to manipulate, it is approximated as a multi-user detector followed by a physical layer network coding encoder, based on which the closed-form relay decoding error is obtained. It is further shown that the ML source decoder is actually equivalent to the typical DBPSK decoder to the relay-source channel, and the exact end-to-end Bit Error Rate (BER) is derived then. A power allocation problem is also formulated to minimize the average BER at high Signal-to-Noise Ratio (SNR). It is shown that the optimal source power is inversely proportional to the square root of the channel gain of the source-relay channel, and the optimal relay power decreases with SNR.
Concealability-rate-distortion tradeoff in image compression anti-forensics

Due to the ease with which digital multimedia content can be modified, a number of techniques to forensically detect forgeries have been developed. Meanwhile, anti-forensic operations have been developed to defeat forensic techniques. When anti-forensics is applied, a forger must balance between the amount that editing fingerprints have been concealed and the distortion introduced to the content. Additionally, the forger may compress the forgery for storage or transmission, which introduces a tradeoff between data rate and distortion. In this paper, we define a measure of an anti-forensic technique's effectiveness which we call concealability and examine the tradeoff between concealability, rate, and distortion. We then characterize the concealability-rate-distortion (C-R-D) surface for double JPEG compression anti-forensics. To do this, we propose a new technique known as flexible anti-forensic dither to hide double JPEG fingerprints. From our experiments, we identify two surprising results related to the C-R-D surface.
Statistical Delay QoS Protection for Primary Users in Cooperative Cognitive Radio Networks

In cooperative cognitive radio networks, where secondary users (SU) can relay the signal of primary user (PU) in exchange for PU's licensed spectrum, most existing works employ deterministic quality-of-service (QoS) guarantee in terms of minimum required transmission rate for PU's protection. In this letter, we adopt the statistical QoS requirement characterized by queue-length bound violation probability for PU's delay QoS provisioning. By applying the effective capacity theory, we further convert PU's queue-length bound violation probability requirement to the equivalent effective capacity constraint and formulate the corresponding SU's throughput maximization problem. Then, we obtain the optimal joint time-slot allocation scheme, where the time-slot division adapts to both channel conditions and PU's delay QoS requirements, such that not only PU's statistical delay QoS requirement can be well guaranteed, but also SU's throughput can be optimized. Moreover, we also develop a fixed time-slot allocation scheme that only varies with PU's delay QoS requirements. Simulation results show that both the optimal and fixed allocation schemes can flexibly perform time-slot divisions according to the delay QoS requirements of PU's traffic, but the developed optimal scheme outperforms the fixed time-slot allocation scheme.
Combining power control and blind equalization in wireless networks

Decentralized power control techniques achieve a target SINR (signal to interference-noise ratio) in wireless networks assuming knowledge of link gains and measurement of interference powers. We propose a joint power control-blind equalization algorithm that redefines the power control problem and importantly, does not need measurement of link gains and interference powers at the base station or sending a training sequence. We consider uplink transmission with multiple reception at each station. Convergence of the algorithm for low delay spread channels is shown theoretically and verified by simulation. The proposed scheme also enables users to achieve a desired bit error rate based directly on a selectable threshold. In the traditional scenario, an error in the assumed channel and array response causes a steep degradation in performance while our algorithm does nor degrade though there is error in the estimated response from blind equalization.
Joint Spectrum Sensing and Access Evolutionary Game in Cognitive Radio Networks

Many spectrum sensing methods and dynamic access algorithms have been proposed to improve the secondary users' opportunities of utilizing the primary users' spectrum resources. However, few of them have considered to integrate the design of spectrum sensing and access algorithms together by taking into account the mutual influence between them. In this paper, we propose to jointly analyze the spectrum sensing and access problem by studying two scenarios: synchronous scenario where the primary network is slotted and non-slotted asynchronous scenario. Due to selfish nature, secondary users tend to act selfishly to access the channel without contribution to the spectrum sensing. Moreover, they may take out-of-equilibrium strategies because of the uncertainty of others' strategies. To model the complicated interactions among secondary users, we formulate the joint spectrum sensing and access problem as an evolutionary game and derive the evolutionarily stable strategy (ESS) that no one will deviate from. Furthermore, we design a distributed learning algorithm for the secondary users to converge to the ESS. With the proposed algorithm, each secondary user senses and accesses the primary channel with the probabilities learned purely from its own past utility history, and finally achieves the desired ESS. Simulation results shows that our system can quickly converge to the ESS and such an ESS is robust to the sudden unfavorable deviations of the selfish secondary users.
Anti-forensics for frame deletion/addition in MPEG video

Due to the ease with which digital information can be altered, many digital forensic techniques have recently been developed to authenticate multimedia content. One important digital forensic result is that adding or deleting frames from an MPEG video sequence introduces a temporally distributed fingerprint into the video can be used to identify frame deletion or addition. By contrast, very little research exists into anti-forensic operations designed to make digital forgeries undetectable by forensic techniques. In this paper, we propose an anti-forensic technique capable of removing the temporal fingerprint from MPEG videos that have undergone frame addition or deletion. We demonstrate that our proposed anti-forensic technique can effectively remove this fingerprint through a series of experiments.
On QoS constraints and joint source-channel coding for real-time cooperative multimedia communications

Cooperative diversity exploits the broadcast nature of wireless channels by allowing users to relay information for each other so as to create multiple signal paths. This technique could be used together with joint source-channel bit rate allocation to transmit conversational multimedia traffic. This paper studies, following a methodology that avoids the use of high or low SNR approximations, the interaction between joint source-channel bit rate allocation with AF and DF cooperation. Furthermore, the effect of QoS constraints on performance is studied. In addition to the advantages of user-cooperation at medium and low source-destination channel signal-to-noise ratio, the results in this paper point at the fact that significant extra performance gains could be obtained by careful selection of the relay node. Guidelines for choosing the relay are also discussed
Differential transmission for amplify-and-forward Cooperative communications

In this letter, we propose a differential amplify-and-forward (AF) transmission scheme for a two-user cooperative communications system. By efficiently combining signals from both direct and relay links, the proposed scheme provides superior performance compared to those of direct transmissions with either differential detection or coherent detection. While the exact bit-error-rate (BER) formulation of the proposed scheme is not available currently, we provide, as a performance benchmark, an exact BER formulation and its simple bounds for a case of optimum-combining cooperation system with differential M-ary phase-shift keying (DMPSK) signals. The optimum power allocation is also determined based on the provided BER formulations. We show that the proposed differential cooperative transmission scheme together with the optimum power allocation yields comparable performance to the optimum-combining scheme. Simulation results show that the proposed differential scheme with optimum power allocation yields significant performance improvement over that with an equal power allocation scheme.
Eigen-selection approach for joint beamforming and space-frequency coding in MIMO-OFDM systems with spatial correlation feedback

This paper addresses the problem of joint optimization of transmit beamforming and space-frequency (SF) coding for MIMO-OFDM systems with spatial correlation feedback. This problem is challenging in the sense that the transmitter should be designed to beamform across multiple eigenspaces. The performance analysis for SF-coded MIMO-OFDM systems with beamforming is provided, and a general optimization problem for the beamforming design is formulated. Three suboptimal approaches to design the beamformer based on the derived design criteria are proposed. In terms of bit error rate, simulations show that improvement in the performance over SF coding without beamforming is about 3 dB for highly correlated channels.
Image and video transmission over wireless channel: a subband modulation approach

A new approach to reliable image and video transmission over a noisy channel is proposed. The proposed subband modulation scheme combines source coding and a channel modulation scheme to achieve high compression efficiency and preferable quality. Further performance gain is obtained by multiresolution modulation and bits re-mapping scheme that assign efficient mapping from source codeword to channel modulation points. The bits re-mapping scheme performs nearly the same as the optimal mapping design scheme (Lervik and Ramstad, 1996) but with much lower complexity. The simulation is carried out on an additive white Gaussian noise (AWGN) channel, and extended to the slow Rayleigh fading channel.
Differential modulation for multi-node amplify-and-forward wireless relay networks

In this paper, we propose a multi-node differential amplify-and-forward scheme for cooperative communications. The proposed scheme efficiently combines signals from the direct and multiple relay links to improve communication reliability. Bit-error-rate (BER) analysis for M-ary differential phase shift keying is provided as performance measure of the proposed scheme, and optimum power allocation is investigated. While the exact BER formulation of the proposed scheme is not available currently, we provide as a performance benchmark a tight BER formulation based on optimum combining weights. A simple BER upper bound and a tight BER approximation show that the proposed scheme can achieve the full diversity which equals to the number of cooperating nodes. We further provide simple BER approximation in order to provide analytical result on power allocation scheme. A closed-form optimum power allocation based on the tight simple BER approximation is obtained for single-relay scenario. An approximate optimum power allocation scheme is provided for multi-relay systems. The provided BER formulations are shown to closely match to the simulation results. Moreover, simulation results show that the optimum power allocation scheme achieves up to 2 dB performance gain over the equal power allocation scheme
Real-time parallel and fully pipelined two-dimensional DCT lattice structures with application to HDTV systems

The authors propose a fully pipelined architecture to compute the 2D discrete cosine transform (DCT) from a frame-recursive point of view. Based on this approach, two real-time parallel lattice structures for successive frame and block 2D DCT are developed. These structures are fully pipelined with throughput rate N clock cycles for an N*N successive input data frame. Moreover, the resulting 2D DCT architectures are modular, regular, and locally connected and require only two 1D DCT blocks that are extended directly from the 1D DCT structure without transposition. It is therefore suitable for VLSI implementation for high-speed HDTV systems. A parallel 2D DCT architecture and a scanning pattern for HDTV systems to achieve higher performance is proposed. The VLSI implementation of the 2D DCT using distributed arithmetic to increase computational efficiency and reduce round-off error is discussed.
Transform domain motion estimation without macroblock-based repetitive padding for MPEG-4 video

In order to perform motion estimation and compensation (ME/MC) of an arbitrarily shaped video object plane (VOP), macroblock-based repetitive padding is applied to the blocks on the borders of the reference VOP in MPEG-4 video. However the padding undesirably increases the overall complexity and data flow. In this paper, we propose transform domain motion estimation without repetitive padding for MPEG-4 video. It directly extracts motion vectors out of the two consecutive VOPs of the moving object. The resulted approach has low computational complexity, O(N/sup 2/) compared to O(N/sup 4/) for the modified block (polygon) matching motion estimation (MBKM-ME) in MPEG-4 video verification model (VM). Most importantly, the DCT-based nature enables the combination of both DCT and motion estimation units, thus the simplification of the heavily loaded feedback loop in MPEG-4 video coder design. It leads to a low-complexity, high-throughput fully DCT-based video coder. Moreover the proposed algorithm has inherently massive parallel operations and local connections suitable for VLSI implementation. Simulation demonstrates comparable performance of our transform domain approach and MBKM-ME in MPEG-4 video VM in terms of prediction errors.
Cooperation in Random Access Networks: Protocol Design and Performance Analysis

This paper tries to answer the questions of how to enable cooperative communications in random access networks. And, since cooperation introduces extra transmissions in the channel, what are the benefits and possible tradeoffs associated with cooperation? To answer these questions, a novel cooperative protocol for wireless networks based on IEEE 802.11 random access protocol is proposed. Cooperation is achieved through the deployment of a relay node that intelligently access the wireless medium without imposing any penalties in terms of increased collision probability. To help other network nodes, relay stores packets in its queue, and accesses the channel after each transmission attempt made by any network node. Using this scheme, relay is guaranteed uncontested access to the channel. To capture the interactions between different network nodes and the relay, the network is modeled using Markov chains in conjunction with queuing analysis. Throughput and delay performances of the proposed protocol are characterized and compared to CSMA/CA without cooperation. The results demonstrate that significant gains are achieved by the proposed cooperative protocols.
Single-block differential transmit scheme for broadband wireless MIMO-OFDM systems

In frequency-selective multiple-input multiple-output (MIMO) channel, differential space-time-frequency (DSTF) modulations are known as practical alternatives that are capable of exploiting the available spatial and frequency diversities without the requirement of multichannel estimation at the receiver. However, the encoding nature of the DSTF schemes that expand several OFDM symbol periods makes the DSTF schemes susceptible to fast-changing channel conditions. In this paper, we propose a differential scheme for MIMO-OFDM systems that is able to differentially encode signal within two OFDM symbol periods, and the proposed scheme transmits the differentially encoded signal within one OFDM block. The scheme not only reduces encoding and decoding delay but also relaxes the restriction on channel assumption. The successful differential decoding of the proposed scheme depends on the assumption that the fading channels keep constant over two OFDM symbol periods rather than multiple of them as required in the existing DSTF schemes. We also provide pairwise error probability analysis and quantify the performance criteria in terms of diversity and coding advantages. The design criteria reveal that the existing diagonal cyclic codes can be applied to achieve full diversity. Performance simulations under various channel conditions show that our proposed scheme yields superior performance to previously proposed differential schemes
Anti-collusion forensics of multimedia fingerprinting using orthogonal modulation

Digital fingerprinting is a method for protecting digital data in which fingerprints that are embedded in multimedia are capable of identifying unauthorized use of digital content. A powerful attack that can be employed to reduce this tracing capability is collusion, where several users combine their copies of the same content to attenuate/remove the original fingerprints. In this paper, we study the collusion resistance of a fingerprinting system employing Gaussian distributed fingerprints and orthogonal modulation. We introduce the maximum detector and the thresholding detector for colluder identification. We then analyze the collusion resistance of a system to the averaging collusion attack for the performance criteria represented by the probability of a false negative and the probability of a false positive. Lower and upper bounds for the maximum number of colluders K/sub max/ are derived. We then show that the detectors are robust to different collusion attacks. We further study different sets of performance criteria, and our results indicate that attacks based on a few dozen independent copies can confound such a fingerprinting system. We also propose a likelihood-based approach to estimate the number of colluders. Finally, we demonstrate the performance for detecting colluders through experiments using real images.
Why Time Reversal for Future 5G Wireless? [Perspectives]

As the demand for wireless voice and data services has continued to grow dramatically, operators struggle to satisfy this demand with acceptable quality of service. The main approach until now was to increase the system bandwidth and spectral efficiency. For instance, there was an almost tenfold increase for each new generation of cellular technology [the first generation (1G) technology can support up to 30 kHz, second generation (2G) around 200 kHz, third generation (3G) around 1.25-5 MHz, and fourth generation (4G) up to 20 MHz]. Meanwhile, technologists have begun seeking more innovative and efficient communication technologies to meet the ever-increasing demand for data traffic with advanced signal processing capabilities for the 5G wireless communication systems. It is expected that 95% of data traffic will come from indoor locations in a few years . Compared to outdoor propagation, wireless medium in an indoor environment often exhibits richer multipath propagation mostly without a strong line-of-sight (LOS) component, which makes the design of 5G indoor communication systems even more challenging.