Physical Layer Service Integration in 5G: Potentials and Challenges

High transmission rate and secure communication have been identified as the key targets that need to be effectively addressed by fifth generation (5G) wireless systems. In this context, the concept of physical-layer security becomes attractive, as it can establish perfect security using only the characteristics of wireless medium. Nonetheless, to further increase the spectral efficiency, an emerging concept, termed physical-layer service integration (PHY-SI), has been recognized as an effective means. Its basic idea is to combine multiple coexisting services, i.e., multicast/broadcast service and confidential service, into one integral service for one-time transmission at the transmitter side. This article first provides a tutorial on typical PHY-SI models. Furthermore, we propose some state-of-the-art solutions to improve the overall performance of PHY-SI in certain important communication scenarios. In particular, we highlight the extension of several concepts borrowed from conventional single-service communications, such as artificial noise (AN), eigenmode transmission etc., to the scenario of PHY-SI. These techniques are shown to be effective in the design of reliable and robust PHY-SI schemes. Finally, several potential research directions are identified for future work.Comment: 12 pages, 7 figure

Artificial Noise-Aided Biobjective Transmitter Optimization for Service Integration in Multi-User MIMO Gaussian Broadcast Channel

This paper considers an artificial noise (AN)-aided transmit design for multi-user MIMO systems with integrated services. Specifically, two sorts of service messages are combined and served simultaneously: one multicast message intended for all receivers and one confidential message intended for only one receiver and required to be perfectly secure from other unauthorized receivers. Our interest lies in the joint design of input covariances of the multicast message, confidential message and artificial noise (AN), such that the achievable secrecy rate and multicast rate are simultaneously maximized. This problem is identified as a secrecy rate region maximization (SRRM) problem in the context of physical-layer service integration. Since this bi-objective optimization problem is inherently complex to solve, we put forward two different scalarization methods to convert it into a scalar optimization problem. First, we propose to prefix the multicast rate as a constant, and accordingly, the primal biobjective problem is converted into a secrecy rate maximization (SRM) problem with quality of multicast service (QoMS) constraint. By varying the constant, we can obtain different Pareto optimal points. The resulting SRM problem can be iteratively solved via a provably convergent difference-of-concave (DC) algorithm. In the second method, we aim to maximize the weighted sum of the secrecy rate and the multicast rate. Through varying the weighted vector, one can also obtain different Pareto optimal points. We show that this weighted sum rate maximization (WSRM) problem can be recast into a primal decomposable form, which is amenable to alternating optimization (AO). Then we compare these two scalarization methods in terms of their overall performance and computational complexity via theoretical analysis as well as numerical simulation, based on which new insights can be drawn.Comment: 14 pages, 5 figure

The Bronze Weapons of the Late Shang Period.

Bronze weapons are one of the two most important products of the Chinese Bronze Age. Both ritual vessels and weapons were utilized for the two most crucial affairs of the state during the Bronze Age in China. From 1937 up to the present day, a period of almost sixty years, archaeologists have continuously been revealing a more detailed picture of Yinxu bronze culture. In comparison with bronze ritual vessels, the bronze weapons of Bronze Age China remain relatively unexplored. On the basis of the archaeological excavations the Late Shang bronze weapons in this thesis have been studied from the points of view of the history of bronze art, sacrificial rituals and cultural relationships between Anyang and the peripheral areas. The Late Shang period was a turning point in bronze weaponry. Clear changes occurred in their quantity, quality and regional distribution. The bronze weapons became a common element among the tomb furnishings. This reflects parallels between the development of weapons and political and social changes. The transformation from the use of jade to the use of bronze for weapons, could reflect the formation or increase of a certain class which required a burial to include bronze weapons. For reasons of social or political status members of this class received a degree of ritualized burial. At the same time, the high-ranking members of the military had their own ritual code for burial, producing a situation where weapons and status were even more subtly differentiated. Bronze weapons were not widely and relatively densely distributed in China until the Late Shang period. There was an imbalance in the distribution of Late Shang bronze weapons and Anyang was one of the largest centres. The importance of the bronze ge in the burial system at Anyang was established. At the same time, the rudiments of regional characteristics are clearly seen in this period in regions outside Anyang and regional styles of the bronze weapon became obvious. The distribution of regional styles of bronze weapons reflects the very important cultural phenomenon that some regional characteristics are limited to a single area. Other indigenous styles are not restricted to their area of origin, but are dispersed over wider regions, typically encompassing two or more areas creating "a phenomenon where distinct cultural regions share selective stylistic characteristics." In contrast to those regional styles of bronze weapons which are limited in their range of distribution, the metropolitan style centered around Anyang was distributed over a much larger area. A complex system of designs on the bronze weapons was formed and a new phase in casting techniques was achieved through the changes of their social and political roles. There was an increase in the diversity of their types and forms. The various motifs, the inlay, openwork and mixing materials were used in the art of bronze weapons. The bronze weapons in Late Shang, as manifestations of artistic, political, and social phenomenon, found their place in the art history of bronzes

Research on the Willingness to Accept Mobile Internet Advertising Based on Customer Perception---A Case of College Students

The role of the mobile terminal in advertising and marketing has attached increasing attention, but the traditional advertising acceptance model does not consider how the characteristics of mobile Internet advertising affect consumer attitudes and decision-making. Based on the technology acceptance model (TAM) and the characteristics of groups of college students, a research model of college students\u27 willingness to accept mobile Internet advertising is established. The data of college students\u27 perception and evaluation of mobile Internet advertising are collected by means of questionnaire, and the data are analyzed by SPSS. The results show that the perceived entertainment of mobile Internet advertising and social influence have a significant positive impact on college students\u27 willingness to accept mobile Internet advertising, and the impact of perceived usefulness is not significant. According to the research conclusions, some useful inspirations are put forward for the design and promotion of mobile Internet advertising

Side-chain Charge Effects and Conductance Determinants in the Pore of ClC-0 Chloride Channels

The charge on the side chain of the internal pore residue lysine 519 (K519) of the Torpedo ClC-0 chloride (Cl−) channel affects channel conductance. Experiments that replace wild-type (WT) lysine with neutral or negatively charged residues or that modify the K519C mutant with various methane thiosulfonate (MTS) reagents show that the conductance of the channel decreases when the charge at position 519 is made more negative. This charge effect on the channel conductance diminishes in the presence of a high intracellular Cl− concentration ([Cl−]i). However, the application of high concentrations of nonpermeant ions, such as glutamate or sulfate (SO42−), does not change the conductance, suggesting that the electrostatic effects created by the charge at position 519 are unlikely due to a surface charge mechanism. Another pore residue, glutamate 127 (E127), plays an even more critical role in controlling channel conductance. This negatively charged residue, based on the structures of the homologous bacterial ClC channels, lies 4–5 Å from K519. Altering the charge of this residue can influence the apparent Cl− affinity as well as the saturated pore conductance in the conductance-Cl− activity curve. Amino acid residues at the selectivity filter also control the pore conductance but mutating these residues mainly affects the maximal pore conductance. These results suggest at least two different conductance determinants in the pore of ClC-0, consistent with the most recent crystal structure of the bacterial ClC channel solved to 2.5 Å, in which multiple Cl−-binding sites were identified in the pore. Thus, we suggest that the occupancy of the internal Cl−-binding site is directly controlled by the charged residues located at the inner pore mouth. On the other hand, the Cl−-binding site at the selectivity filter controls the exit rate of Cl− and therefore determines the maximal channel conductance

Different Fast-Gate Regulation by External Cl− and H+ of the Muscle-Type Clc Chloride Channels

The fast gate of the muscle-type ClC channels (ClC-0 and ClC-1) opens in response to the change of membrane potential (V). This gating process is intimately associated with the binding of external Cl− to the channel pore in a way that the occupancy of Cl− on the binding site increases the channel's open probability (Po). External H+ also enhances the fast-gate opening in these channels, prompting a hypothesis that protonation of the binding site may increase the Cl− binding affinity, and this is possibly the underlying mechanism for the H+ modulation. However, Cl− and H+, modulate the fast-gate Po-V curve in different ways. Varying the external Cl− concentrations ([Cl−]o) shifts the Po-V curve in parallel along the voltage axis, whereas reducing external pH mainly increases the minimal Po of the curve. Furthermore, H+ modulations at saturating and nonsaturating [Cl−]o are similar. Thus, the H+ effect on the fast gating appears not to be a consequence of an increase in the Cl− binding affinity. We previously found that a hyperpolarization-favored opening process is important to determine the fast-gate Po of ClC-0 at very negative voltages. This [Cl−]o-independent mechanism attracted little attention, but it appears to be the opening process that is modulated by external H+

Rapidity bin multiplicity correlations from a multi-phase transport model

The central-arbitrary bin and forward-backward bin multiplicity correlation patterns for Au+Au collisions at $\sqrt{s_{NN}}$= $7.7-62.4$ GeV are investigated within a multi-phase transport (AMPT) model. An interesting observation is that for $\sqrt{s_{NN}} <19.6$ GeV Au+Au collisions, these two correlation patterns both have an increase with the pseudorapidity gap, while for $\sqrt{s_{NN}} >19.6$ GeV Au+Au collisions, they decrease. We mainly discuss the influence of different evolution stages of collision system on the central-arbitrary bin correlations, such as the initial conditions, partonic scatterings, hadronization scheme and hadronic scatterings. Our results show that the central-arbitrary bin multiplicity correlations have different responses to partonic phase and hadronic phase, which can be suggested as a good probe to explore the dynamical evolution mechanism of the hot dense matter in high-energy heavy-ion collisions.Comment: 7pages, 6 figures, accepted for publication in EPJ

Electrostatic Control and Chloride Regulation of the Fast Gating of ClC-0 Chloride Channels

The opening and closing of chloride (Cl−) channels in the ClC family are thought to tightly couple to ion permeation through the channel pore. In the prototype channel of the family, the ClC-0 channel from the Torpedo electric organ, the opening-closing of the pore in the millisecond time range known as “fast gating” is regulated by both external and internal Cl− ions. Although the external Cl− effect on the fast-gate opening has been extensively studied at a quantitative level, the internal Cl− regulation remains to be characterized. In this study, we examine the internal Cl− effects and the electrostatic controls of the fast-gating mechanism. While having little effect on the opening rate, raising [Cl−]i reduces the closing rate (or increases the open time) of the fast gate, with an apparent affinity of >1 M, a value very different from the one observed in the external Cl− regulation on the opening rate. Mutating charged residues in the pore also changes the fast-gating properties—the effects are more prominent on the closing rate than on the opening rate, a phenomenon similar to the effect of [Cl−]i on the fast gating. Thus, the alteration of fast-gate closing by charge mutations may come from a combination of two effects: a direct electrostatic interaction between the manipulated charge and the negatively charged glutamate gate and a repulsive force on the gate mediated by the permeant ion. Likewise, the regulations of internal Cl− on the fast gating may also be due to the competition of Cl− with the glutamate gate as well as the overall more negative potential brought to the pore by the binding of Cl−. In contrast, the opening rate of the fast gate is only minimally affected by manipulations of [Cl−]i and charges in the inner pore region. The very different nature of external and internal Cl− regulations on the fast gating thus may suggest that the opening and the closing of the fast gate are not microscopically reversible processes, but form a nonequilibrium cycle in the ClC-0 fast-gating mechanism