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Orthogonal frequency division multiplexing (OFDM) modulations are very popular in wireless communications due to their flexibility and good performance over severely time-dispersive channels. However, OFDM signals have large peak-to-average power ratio (PAPR), which leads to amplification problems. Constant envelope OFDM (CE-OFDM) techniques use an OFDM signal to modulate the phase of a given carrier,...
In this paper, we propose a method that skips the complex encoding processes of coding unit (CU) for HEVC intra frame coding. To speed-up the encoding process that recursively explore all sizes of CUs, most researchers have exploited spatial information thus far. On the other hand, the temporal correlation among frames has not been thoroughly investigated. We exploited the temporal correlation as...
Recently, LTE Release 12 and IEEE 802.11ac adopted 256-quadrature amplitude modulation (QAM) as a tool to accommodate high demand of data throughput in wireless systems. Furthermore, currently developing IEEE 802.11ax considers 1024-QAM to further increase the Wi-Fi throughput. In this paper, we propose low complexity schemes in soft detection of high order QAM symbols in multiple input multiple output...
In this paper, we propose a novel method of reducing the complexity of a pilot-based two-dimensional linear minimum mean square error (2D LMMSE) channel estimation scheme for orthogonal frequency division multiplexing (OFDM) systems. We identify that the 2D LMMSE channel estimation method aided by pilots embedded in a two-dimensional OFDM resource grid can be decoupled into three steps: (a) pilot...
The Maintainability Index (MI) metric was proposed in the early nineties to gauge ease of code maintenance. A high value of MI indicates well-constructed code which is easy to maintain and a low MI, the opposite. The metric has been criticized in the past and more recently for its applicability to code and validity more generally. Very few studies however have explored whether the MI correlates strongly...
Software quality is one of the important aspects of the reliable software. For this reason, software practitioners are interested in the methods that enable to predict defect with software metrics. Most studies focus on what kind of techniques would be fit for the prediction model; however, the research about what is the appropriate number of software metrics for building effective defect prediction...
Eigen-beamforming is an optimal beamforming scheme for full-dimension multi-input multi-output (FD-MIMO). However, it suffers from high complexity of the singular value decomposition (SVD) of the 3D channel matrix. In this paper, we propose a low complexity dual layer beamforming scheme to exploit both the horizontal and vertical degrees of freedom. The proposed scheme first segments the channel matrix...
Intuitionistic Fuzzy Set (IFS) is considered as a nature solution for information fusion. How to transform the information with non-uniform distribution into IFS? In this paper, the authors proposed an approach to deal with this challenge. First, the intensive region (IR) of non-uniform distribution data is searched. Second, the evaluation grades are assigned to IR and other regions. IR is assigned...
In cognitive radio networks, the task of spectrum sensing is required to be reliable at low signal-to-noise ratios (SNRs). Spectral correlation is an effective approach to satisfy the requirement. The algorithms based on statistic spectral correlation profiles are a good method as shown in some previous works. In this paper, we propose an algorithm with maximum ratio combination for the profiles to...
The estimation of carrier frequency offset (CFO) and in-phase and quadrature-phase (I/Q) imbalance is an important issue in the study of the orthogonal frequency division multiplexing (OFDM) systems. In our recent work [6], we have proposed a blind algorithm for the estimation of CFO in the absence of I/Q imbalance. In this paper, a blind algorithm is introduced for the estimation of I/Q parameter...
As an overlay cognitive radio, transform domain communication system (TDCS) has been proposed to support reliable communications with low probability of interception. However, most of research on TDCS assume perfect synchronization to simplify algorithm design. In this paper, we present a low complexity symbol timing offset (STO) and carrier frequency offset (CFO) estimation method for practical TDCS...
Sensor pattern noise (SPN) has been proved to be an inherent fingerprint of a camera, and it has been broadly used in the fields of image authentication and camera source identification. However, the SPN extracted using current denoising algorithm always contains image content residual, which would significatively influence the accuracy of camera source identification. In this paper, a novel patch-based...
In software testing, test oracles do not always exist or are too hard to generate, which is called "test oracle problem". Metamorphic testing (MT) provide an effective way to alleviate the problem based on metamorphic relations (MR). As a MR is satisfied by a set of test cases, it does not mean that the test cases are success. Therefore, more MRs are needed to improve the effectiveness of...
Previous studies have reported that the performance of a developer can greatly impact the quality of the software he/she has worked on. Such performance can be measured using two developer risk metrics during a particular development period. One is the ratio of the number of bug-introduce commits to the total number of commits made by a developer (i.e., the DQ metric). The other is the proportion...
LABS stand for low autocorrelation binary sequence. LABS detection is a classic problem in the literature. LABS are used in Radar pulse compression techniques to improve the visibility of the targets. As the autocorrelation value decreases, the ability of the radar to detect multiple targets increases. Since 1950's numerous methods were developed to solve LABS problem[13]. In the present case Rudin...
In many applications such as sensor networks, e-healthcare and environmental monitoring, data is continuously streamed and combined from multiple resources in order to make decisions based on the aggregated data streams. One major concern in these applications is assuring high trustworthiness of the aggregated data stream for correct decision-making. For example, an adversary may compromise a few...
Prediction-error expansion (PEE) is an efficient technique for reversible data hiding (RDH). Instead of expanding the highest histogram bins in conventional PEE, in this paper, to better utilize the image redundancy, we propose a new PEE-based RDH scheme with an advisable expansion strategy utilizing referential prediction-errors. For each pixel, we first calculate its prediction-error and use its...
The high cost and power consumption of the radio frequency chain and data converters at mmWave frequencies introduce hardware limitations into the design of MIMO precoders and combiners. MmWave hybrid precoding overcomes this limitation by dividing the spatial signal processing between the radio frequency and baseband domains. Analog networks of phase shifters have been proposed to implement the radio...
Linear complexity is a measure of how complex a one dimensional sequence can be. In this paper we extend the concept of linear complexity to multiple dimensions and present a definition that is invariant under well-orderings of the arrays. As a result we find that our new definition for the process introduced in the patent titled “Digital Watermarking” produces arrays with good asymptotic properties.
TDKC's Compositing Overlays for Maps and Operational Symbologies in Real-Time (COMPOSIT) project is developing innovative ways to automatically overlay digital map, feature, and symbol graphics upon real-time video. Novel, distributive, vector data to video frame registration methods; and innovative, real-time, GIS-based metadata correction techniques are presented and discussed.
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