Search

Non-orthogonal multiple access (NOMA) as an efficient method of radio resource sharing has its roots in network information theory. For generations of wireless communication systems design, orthogonal multiple access schemes in the time, frequency, or code domain have been the main choices due to the limited processing capability in the transceiver hardware, as well as the modest traffic demands in both latency and connectivity. However, for the next generation radio systems, given its vision to connect everything and the much evolved hardware capability, NOMA has been identified as a promising technology to help achieve all the targets in system capacity, user connectivity, and service latency. This article provides a systematic overview of the state-of-theart design of the NOMA transmission based on a unified transceiver design framework, the related standardization progress, and some promising use cases in future cellular networks, based on which interested researchers can get a quick start in this area.

A new iris location method is presented in this paper. When locating the iris inner boundary, a method for locating the iris inner boundary based on the variation coefficient and multiple disk-structural elements is proposed. The variation coefficient of the iris image is first calculated to be used for the image gray stretch, then the mathematical morphology operations with multiple disk-structural elements are applied to tackle the binary iris image, finally the connected region in line with geometric features of the circle is picked up and its center and radius are calculated, namely for obtaining the iris inner boundary. When positioning the iris outer boundary, a method for locating the iris outer boundary based on the variation coefficient and the gradient amplitude is presented. First, the Gaussian function is employed to filter the iris image using the variation coefficient as its standard deviation, then for each pixel on a circle which is centered at each neighborhood pixel near the circle enter of the iris inner boundary and has a radius with greater than that of the inner boundary, the radial gradient amplitude and tangential gradient amplitude of are computed, finally the iris outer boundary is determined on the maximum of the tangential gradient amplitude. The experiments reveal that this proposed method is effective, and has a fairly simple implementation, a low computational load, a fast location and good accuracy.

The pilot spoofing attack is one kind of active eavesdropping activities conducted by a malicious user during the channel training phase. By transmitting the identical pilot (training) signals as those of the legal users, such an attack is able to manipulate the channel estimation outcome, which may result in a larger channel rate for the adversary but a smaller channel rate for the legitimate receiver. With the intention of detecting the pilot spoofing attack and minimizing its damages, we design a two-way training-based scheme. The effective detector exploits the intrusive component created by the adversary, followed by a secure beamforming-assisted data transmission. In addition to the solid detection performance, this scheme is also capable of obtaining the estimations of both legitimate and illegitimate channels, which allows the users to achieve secure communication in the presence of pilot spoofing attack. The detection probability is evaluated based on the derived test threshold at a given requirement on the probability of false alarming. The achievable secrecy rate is utilized to measure the security level of the data transmission. Our analysis shows that even without any pre-assumed knowledge of eavesdropper, the proposed scheme is still able to achieve the maximal secrecy rate in certain cases. Numerical results are provided to show that our scheme could achieve a high detection probability as well as secure transmission.

While most East Asian countries have opted for a hedge strategy to preserve a maximum range of strategic options in response to the rise of China, some countries have engaged in geostrategic balance through collective bargaining and strategic alignments with the US and with each other. The divergent threat perceptions and complicated historical animosities among East Asian countries, however, have set a limitation on the geostrategic balance. Therefore, to bandwagon with China could be a realistic choice for many countries. Historically, the most successful rising powers have been those which attracted the greatest number of bandwagoners. China cannot rise successfully without winning the support of its Asian neighbors. The long term peace and stability in the region, therefore, depends not only on whether China’s neighbors can work together to balance China but also whether China can balance its relationships in its own backyard so that its neighbors find bandwagoning a positive choice.

New multiple access method has been recognized as an enabling technology for fifth-generation (5G) communication system. To fulfill the requirement on higher user density/network throughput, conventional orthogonal multiple access schemes have certain limitation on the user-capacity by only configuring the resource to one user. In this paper, an advanced non-orthogonal multiple access (NoMA) scheme is proposed, namely as interleave-grid multiple access (IGMA). Based on the bit level interleaving and symbol level grid-mapping process, the IGMA can provide tremendous user multiplexing capability as well as BLER performance. Joint detection and decoding technique is utilized at the receiver side considering both the complexity and the achievable performance. Moreover, the link level and system level simulation results are represented to verify the performance of IGMA, some initial hardware evaluation is also given.

The pilot spoofing attack is one kind of active eavesdropping conducted by a malicious user during the channel estimation phase of the legitimate transmission. In this attack, an intelligent adversary spoofs the transmitter on the estimation of channel state information (CSI) by sending the identical pilot signal as the legitimate receiver, in order to obtain a larger information rate in the data transmission phase. The pilot spoofing attack could also drastically weaken the strength of the received signal at the legitimate receiver if the adversary utilizes large enough power. Motivated by the serious problems the pilot spoofing attack could cause, we propose an efficient detector, named energy ratio detector (ERD), by exploring the asymmetry of received signal power levels at the transmitter and the legitimate receiver when there exists a pilot spoofing attack. Our analysis shows that by setting the ratio of received signal power levels at the transmitter and the legitimate receiver as the test statistic, the detecting threshold is derived without using the knowledge of the CSI of the legitimate channel as well as the illegitimate channel. Furthermore, we study the performance of the proposed ERD in various special cases in order to obtain useful insights. Numerical results are presented to further demonstrate the performance of our proposed ERD.

In this paper, we proposed a computing resource allocation scheme based on users' SNR condition, to achieve the maximal throughput of wireless networks. So far, most research on radio resource allocation assumed the computing ability is infinite for digital signal processing. In our paper, we assume that the computing resource is limited, and consider the centralized computing scenario, which is popular in the next generation wireless radio access network architecture. First we model the computing ability by iteration times, then we propose the adaptive allocation scheme based on SNR condition. Simulation results show that the proposed scheme can obtain 0.5 dB improvement of system throughput compared with traditional scheme.

With the rapid development of information security technology, Network Based Intrusion Protecting Devices(NIPD), like firewall and NIDS, holding the function of detecting and blocking network attacks, have become the primary security guard of critical information infrastructure, significantly reduced the security threat of network attack. Regarding these features, attackers are continuously pursuing efficient ways for obfuscating attack behaviors to evade from the detecting mechanism of NIPD. Once the NIPD deployed in the network boundary is found vulnerable, malicious attackers can bypass it with advanced evasion technology to deliver an exploit, making the protected network information infrastructure be directly exposure to network threats from outside, which brings in security risks and results in serious consequence. So doing research on the testing technology for the evasion resilience capability of NIPD is critical. This paper first introduced the working mechanism of NIPD, providing a comprehensive survey on the achievements on the field of current evasion resilience testing technology. Then, the defects of the current work are analyzed and improvements on the corresponding work are described accordingly. Finally, the further research directions in this field is discussed in detail.

In this letter, we consider physical layer security in multiple-input single-output (MISO) fading wiretap chan- nels, where the transmitter utilizes a jamming-aided precoding transmission strategy to maximize the achievable secrecy rate of the channel. The instantaneous channel state information (CSI) of the eavesdropper's channel is considered unavailable at the transmitter. We derive the closed-form expression of the ergodic secrecy rate, based on which we find that there exists an optimal power allocation ratio between the information signal and the jamming signal. Asymptotic analysis shows that the optimal power ratio depends on the number of antennas as well as the available transmit power at Alice. Index Terms—Physical layer security, MISO, precoding, jam- ming, imperfect CSI

In order to study the vehicles queuing under traffic accidents, we put the traffic wave analogy into fluid wave, and build traffic wave model, getting the relationship equation: vehicles queue length and the actual capacity of cross-section, accidents duration, section of the upstream traffic. According to analyzing the equation, we get: the maximum queue length increase with upstream traffic as category Index, however, inversely proportional to the actual capacity, and it is positively correlated with the duration of the accident.

In a time-division duplex (TDD) based multi-input single-output (MISO) system, the channel state information (CSI) can be obtained during the channel estimation phase in which the receiver transmits the pilot symbols to the transmitter. This scheme may suffer from a so-called pilot spoofing attack, i.e., an adversary may send identical pilot signals as those of the legitimate receiver to spoof the transmitter. The resultant channel estimate may then contain the CSI of both legitimate and illegitimate receivers, and if such estimated channel is used for transmit beamforming, the information dedicated for legitimate receiver will leak to the illegitimate receiver. In this paper, we study the detection and defending strategies for such pilot spoofing attack. A two-way training based scheme is proposed. The durations of the training periods are also designed to optimize the secrecy rate. Finally, numerical results are presented to show the performance of our proposed method.

As one of the most popular industrial network protocol used in the energy distribution field, the security, especially vulnerability of Modbus-TCP protocol has attracted great attentions from both academic and industrial field. Due to the Particularity of Modbus-TCP, traditional fuzzing framework for vulnerability detecting cannot work efficiently. To overcome this drawback, a special smart fuzzing technology for Modbus-TCP is proposed, the architecture is described in detail, an adaptive algorithm for test case generating and the workflow of the testing process are presented, which can smartly generate test case according to the feedback from target. The result of the simulation experiment show that the mechanism described can satisfy the requirement of the vulnerability detecting for Modbus-TCP well. What's more, compared with traditional fuzzing framework, the quality of the test case and the efficiency of the process are apparently improved without losing the coverage.

We study a spoofing attack happened in the physical layer of a multiple-antenna system, where an adversary tries to spoof the transmitter by sending the identical pilot (training) signal as that of a legitimate receiver in the uplink channel estimation phase. This attack, named as pilot spoofing attack, could lead to a secrecy information leakage to the adversary and information rate decrease at the legitimate receiver. Due to the serious results caused by the pilot spoofing attack, we propose an energy-ratio detector (ERD) to protect the legitimate components. The ERD makes the decision by exploiting the asymmetry of the received signal strength (RSS) between the transmitter and the legitimate receiver when the system is under the pilot spoofing attack. Numerical results are presented to illustrate the effectiveness of our proposed detector.

Hydrocarbon reservoirs can be divided into 3 groups and 8 sub-groups. The 8 sub-groups include hydrocarbon reservoirs caused by: (i) high pressure potential fields; (ii) low pressure potential fields; (iii) release of dissolved gas from oil and water; (iv) buoyancy; (v) capillary pressure; (vi) deep-basin gas accumulations; (vii) coal-bed methane accumulations formed by molecular adsorption; and (viii) hydrate formation. The 8 sub-groups can be more broadly combined into 3 groups: (1) hydrocarbon reservoirs resulted from episodic fluid pressure, which include sub-groups (i) and (ii); (2) hydrocarbon reservoirs caused by steady and continuous hydrocarbon potential difference, including sub-groups (iii)-(v); (3) hydrocarbon reservoirs formed under unconventional conditions, which are represented by sub-groups (vi)-(viii). Hydrocarbon reservoirs with the same dynamic origin can be further subdivided into groups according to their geological settings. With different dynamic origins, various hydrocarbon reservoirs have different distribution patterns and major controlling factors. In order to enhance oil and gas field exploration and increase exploration probabilities of success, it is both important and necessary to study the dynamic mechanisms and associated genetic models for hydrocarbon migration and accumulation.

In this paper, secure transmission is considered in a wireless relay network in the presence of an eavesdropper. A novel hybrid relay scheme, named as relaying-and-jamming (RJ), is advocated to achieve information theoretical security. In the RJ scheme, the relay node is equipped with multiple antennas. It responses for two missions: re-transmitting the information signal from source code and broadcasting the jamming signal to degrade eavesdropper's channel. The objective of this paper is to maximize the achievable ergodic secrecy rate. We are interested in the scenario that eavesdropper's instant channel state information (CSI) is unknown, in which the ergodic secrecy rate expression is derived. The optimal power allocation between information signal and jamming signal at the relay node is found statistically to achieve the largest ergodic secrecy rate. Simulation is carefully designed and respective results are presented to confirm the theoretical analysis and compare with existing work.

Physical layer security in wireless networks has received increasing attention in recent years. In this paper, we consider multiple-input single-output (MISO) fading wiretap channels, where the transmitter utilizes artificial noise-aided precoding (ANaP) transmission strategy to maximize the secrecy capacity of the channel. When the channel state information (CSI) of Eavesdropper's (Eve's) channel is known at Alice, we prove that the optimal ANaP strategy reduces to the conventional precoding strategy, i.e., all the transmit power should be allocated to the precoding of information signal. When the CSI of Eve's channel is unknown at Alice, we find that there exists an optimal power allocation ratio between the information signal and the artificial noise and that this power ratio depends on the number of antennas as well as the available transmit power at Alice. In particular, when the available transmit power at Alice increases or the number of antennas at Alice decreases, more power should be allocated to the artificial noise.

Steganalysis is the opposite art to steganography, whose goal is to detect whether or not the seemly innocent objects like image hiding message. With the explosive growth of the Internet information. Making real time image steganalysis online to detect the malicious use of multimedia documents for covert communication has become more and more difficult. Traditional research on image steganalysis mainly focus on how to improve the accuracy of Steganalysis, few of them pay much attention on the efficiency of the Image Steganalysis technology and the architecture optimizing for Steganalysis service providing. Regarding this problem, this paper proposed a Image Steganalysis Technique Based on Cloud Computing and BP Neutral Network, the structure and workflow of the system is introduced in detail. The result of simulation experiment proves that the import of cloud computing architecture can apparently improve the efficiency of image Steganalysis in the environment of internet and the accuracy of Steganalysis algorithm is acceptable instead of being greatly affected by system load.

Using molecular dynamics (MD) simulation, the ultrafast thermomechanical coupling responses of an immense homogeneous, isotropic copper film with the thickness of 1 μm, which is irradiated by various ultra-short laser pulse trains, are investigated. For the same energy injection, the effect of laser pulse trains is studied and it is observed from the numerical results that the pulse train technology may improve the ultrafast thermomechanical responses of the film significantly. By thoroughly analysing temperature, stress and displacement (strain) of the film, the thermomechanical coupling characteristics between stress, displacement (strain) and temperature are presented perfectly at the atomic scale. It is found that the lattice temperature of the region under tensile stress (or compressive stress) is lower (or higher) than the lattice temperature of the surrounding region, and the positive and negative strain (tensile or compressive) is related to tensile and compressive stress very well.