Biblio

A power amplifier(PA) is inherently nonlinear device and is used in a communication system widely. Due to the nonlinearity of PA, the communication system is hard to work well. Digital predistortion (DPD) is the way to solve this problem. Using Volterra function to fit the PA is what most DPD solutions do. However, when it comes to wideband signal, there is a deduction on the performance of the Volterra function. In this paper, we replace the Volterra function with B-spline function which performs better on fitting PA at wideband signal. And the other benefit is that the orthogonality of coding matrix A could be improved, enhancing the stability of computation. Additionally, we use compressive sampling to reduce the complexity of the function model.

This paper provides an overview of the security service controls that are applied in a big data processing (BDP) system to defend against cyber security attacks. We validate this approach by modeling attacks and effectiveness of security service controls in a sequence of states and transitions. This Finite State Machine (FSM) approach uses the probable effectiveness of security service controls, as defined in the National Institute of Standards and Technology (NIST) Risk Management Framework (RMF). The attacks used in the model are defined in the ATT&CK™ framework. Five different BDP security architecture configurations are considered, spanning from a low-cost default BDP configuration to a more expensive, industry supported layered security architecture. The analysis demonstrates the importance of a multi-layer approach to implementing security in BDP systems. With increasing interest in using BDP systems to analyze sensitive data sets, it is important to understand and justify BDP security architecture configurations with their significant costs. The output of the model demonstrates that over the run time, larger investment in security service controls results in significantly more uptime. There is a significant increase in uptime with a linear increase in security service control investment. We believe that these results support our recommended BDP security architecture. That is, a layered architecture with security service controls integrated into the user interface, boundary, central management of security policies, and applications that incorporate privacy preserving programs. These results enable making BDP systems operational for sensitive data accessed in a multi-tenant environment.

With the increasing number of electric vehicles, the scale of the market also increases. In the past, the electric vehicle market had problems such as opaque information, numerous levels and data leakage, which were criticized for the impact of the overall development and policies of the electric vehicle industry. In view of the problems existing in the transparency and security of big data management transactions of the Internet of vehicles, this paper combs the commercial operation framework of the Internet of Vehicles Platform, analyses the feasibility and necessity of establishing the token system of the Internet of Vehicles Platform, and constructs the token economic system architecture of the Internet of Vehicles Platform and its development path.

With the development of the Internet, the amount of information on the Internet is increasing rapidly, which makes it difficult for people to select the information they really want. A recommendation system is an effective way to solve this problem. Fake users can be injected by criminals to attack the recommendation system; therefore, accurate identification of fake users is a necessary feature of the recommendation system. Existing fake user detection algorithms focus on designing recognition methods for different types of attacks and have limited detection capabilities against unknown or hybrid attacks. The use of deep learning models can automate the extraction of false user scoring features, but neural network models are not applicable to discrete user scoring data. In this paper, random walking is used to rearrange the otherwise discrete user rating data into a rating feature matrix with spatial continuity. The rating data and the text data have some similarity in the distribution mode. By effective analogy, the TextCNN model originally used in NLP domain can be improved and applied to the classification task of rating feature matrix. Combining the ideas of random walking and word vector processing, this paper proposes a TextCNN detection model for user rating data. To verify the validity of the proposed model, the model is tested on MoiveLens dataset against 7 different attack detection algorithms, and exhibits better performance when compared with 4 attack detection algorithms. Especially for the Aop attack, the proposed model has nearly 100% detection performance with F1 - value as the evaluation index.

Machine-Learning-as-a-Service has become increasingly popular, with Recommendation-as-a-Service as one of the representative examples. In such services, providing privacy protection for the users is an important topic. Reviewing privacy-preserving solutions which were proposed in the past decade, privacy and machine learning are often seen as two competing goals at stake. Though improving cryptographic primitives (e.g., secure multi-party computation (SMC) or homomorphic encryption (HE)) or devising sophisticated secure protocols has made a remarkable achievement, but in conjunction with state-of-the-art recommender systems often yields far-from-practical solutions. We tackle this problem from the direction of machine learning. We aim to design crypto-friendly recommendation algorithms, thus to obtain efficient solutions by directly using existing cryptographic tools. In particular, we propose an HE-friendly recommender system, refer to as CryptoRec, which (1) decouples user features from latent feature space, avoiding training the recommendation model on encrypted data; (2) only relies on addition and multiplication operations, making the model straightforwardly compatible with HE schemes. The properties turn recommendation-computations into a simple matrix-multiplication operation. To further improve efficiency, we introduce a sparse-quantization-reuse method which reduces the recommendation-computation time by \$9$\backslash$times\$ (compared to using CryptoRec directly), without compromising the accuracy. We demonstrate the efficiency and accuracy of CryptoRec on three real-world datasets. CryptoRec allows a server to estimate a user's preferences on thousands of items within a few seconds on a single PC, with the user's data homomorphically encrypted, while its prediction accuracy is still competitive with state-of-the-art recommender systems computing over clear data. Our solution enables Recommendation-as-a-Service on large datasets in a nearly real-time (seconds) level.

The widescale use of machine learning algorithms to drive decision-making has highlighted the critical importance of ensuring the interpretability of such models in order to engender trust in their output. The state-of-the-art recommendation systems use black-box latent factor models that provide no explanation of why a recommendation has been made, as they abstract their decision processes to a high-dimensional latent space which is beyond the direct comprehension of humans. We propose a novel approach for extracting explanations from latent factor recommendation systems by training association rules on the output of a matrix factorisation black-box model. By taking advantage of the interpretable structure of association rules, we demonstrate that predictive accuracy of the recommendation model can be maintained whilst yielding explanations with high fidelity to the black-box model on a unique industry dataset. Our approach mitigates the accuracy-interpretability trade-off whilst avoiding the need to sacrifice flexibility or use external data sources. We also contribute to the ill-defined problem of evaluating interpretability.

Taint analysis has been widely applied in ex post facto security applications, such as attack provenance investigation, computer forensic analysis, and reverse engineering. Unfortunately, the high runtime overhead imposed by dynamic taint analysis makes it impractical in many scenarios. The key obstacle is the strict coupling of program execution and taint tracking logic code. To alleviate this performance bottleneck, recent work seeks to offload taint analysis from program execution and run it on a spare core or a different CPU. However, since the taint analysis has heavy data and control dependencies on the program execution, the massive data in recording and transformation overshadow the benefit of decoupling. In this paper, we propose a novel technique to allow very lightweight logging, resulting in much lower execution slowdown, while still permitting us to perform full-featured offline taint analysis. We develop StraightTaint, a hybrid taint analysis tool that completely decouples the program execution and taint analysis. StraightTaint relies on very lightweight logging of the execution information to reconstruct a straight-line code, enabling an offline symbolic taint analysis without frequent data communication with the application. While StraightTaint does not log complete runtime or input values, it is able to precisely identify the causal relationships between sources and sinks, for example. Compared with traditional dynamic taint analysis tools, StraightTaint has much lower application runtime overhead.

Data intensive computing research and technology developments offer the potential of providing significant improvements in several security log management challenges. Approaches to address the complexity, timeliness, expense, diversity, and noise issues have been identified. These improvements are motivated by the increasingly important role of analytics. Machine learning and expert systems that incorporate attack patterns are providing greater detection insights. Finding actionable indicators requires the analysis to combine security event log data with other network data such and access control lists, making the big-data problem even bigger. Automation of threat intelligence is recognized as not complete with limited adoption of standards. With limited progress in anomaly signature detection, movement towards using expert systems has been identified as the path forward. Techniques focus on matching behaviors of attackers to patterns of abnormal activity in the network. The need to stream, parse, and analyze large volumes of small, semi-structured data files can be feasibly addressed through a variety of techniques identified by researchers. This report highlights research in key areas, including protection of the data, performance of the systems and network bandwidth utilization.