Downlink Non-Orthogonal Multiple Access with Limited Feedback

In this paper, we analyze downlink non-orthogonal multiple access (NOMA) networks with limited feedback. Our goal is to derive appropriate transmission rates for rate adaptation and minimize outage probability of minimum rate for the constant-rate data service, based on distributed channel feedback information from receivers. We propose an efficient quantizer with variable-length encoding that approaches the best performance of the case where perfect channel state information is available everywhere. We prove that in the typical application with two receivers, the losses in the minimum rate and outage probability decay at least exponentially with the minimum feedback rate. We analyze the diversity gain and provide a sufficient condition for the quantizer to achieve the maximum diversity order. For NOMA with $K$ receivers where $K > 2$, we solve the minimum rate maximization problem within an accuracy of $\epsilon$ in time complexity of $O\left(K\log\frac{1}{\epsilon}\right)$, then, we apply the previously proposed quantizers for $K = 2$ to the case of $K > 2$. Numerical simulations are presented to demonstrate the efficiency of our proposed quantizers and the accuracy of the analytical results

Distributed Channel Quantization for Two-User Interference Networks

We introduce conferencing-based distributed channel quantizers for two-user interference networks where interference signals are treated as noise. Compared with the conventional distributed quantizers where each receiver quantizes its own channel independently, the proposed quantizers allow multiple rounds of feedback communication in the form of conferencing between receivers. We take the network outage probabilities of sum rate and minimum rate as performance measures and consider quantizer design in the transmission strategies of time sharing and interference transmission. First, we propose distributed quantizers that achieve the optimal network outage probability of sum rate for both time sharing and interference transmission strategies with an average feedback rate of only two bits per channel state. Then, for the time sharing strategy, we propose a distributed quantizer that achieves the optimal network outage probability of minimum rate with finite average feedback rate; conventional quantizers require infinite rate to achieve the same performance. For the interference transmission strategy, a distributed quantizer that can approach the optimal network outage probability of minimum rate closely is also proposed. Numerical simulations confirm that our distributed quantizers based on conferencing outperform the conventional ones.Comment: 30 pages, 4 figure

An Analysis of the Anti-Japanese National United Front and Its Formation Process from the Perspective of Game Theory

The united front is a magic weapon for the victory of the revolution, construction and reform of the Communist Party of China. The formation process of the united front is a kind of game, starting from the perspective of game theory, using the assets exclusiveness theory of economics, combining the Nash equilibrium and historical events, building a game model, analyzing the Anti-Japanese National United Front and its formation process, are of great significance to improve the scientific cognition level of historical research work and united front work

A feedback-driven bubble G24.136+00.436: a possible site of triggered star formation

We present a multi-wavelength study of the IR bubble G24.136+00.436. The J=1-0 observations of $^{12}$CO, $^{13}$CO and C$^{18}$O were carried out with the Purple Mountain Observatory 13.7 m telescope. Molecular gas with a velocity of 94.8 km s$^{-1}$ is found prominently in the southeast of the bubble, shaping as a shell with a total mass of $\sim2\times10^{4}$ $M_{\odot}$. It is likely assembled during the expansion of the bubble. The expanding shell consists of six dense cores. Their dense (a few of $10^{3}$ cm$^{-3}$) and massive (a few of $10^{3}$ $M_{\odot}$) characteristics coupled with the broad linewidths ($>$ 2.5 km s$^{-1}$) suggest they are promising sites of forming high-mass stars or clusters. This could be further consolidated by the detection of compact HII regions in Cores A and E. We tentatively identified and classified 63 candidate YSOs based on the \emph{Spitzer} and UKIDSS data. They are found to be dominantly distributed in regions with strong emission of molecular gas, indicative of active star formation especially in the shell. The HII region inside the bubble is mainly ionized by a $\sim$O8V star(s), of the dynamical age $\sim$1.6 Myr. The enhanced number of candidate YSOs and secondary star formation in the shell as well as time scales involved, indicate a possible scenario of triggering star formation, signified by the "collect and collapse" process.Comment: 13 pages, 10 figures, 4 tables, accepted by Ap

Evaluating Government Portal Websites in China

Government portal websites are the core components of e-Government because it is a platform integrating different government resources. This article was devoted to study the government portal websites in China in order to disclose the development status of e-Government in China. In order to do this, two questions are answered: from which aspects should government portal websites be evaluated; how to develop the indexes for different aspects of government portal website evaluation. In our solution, we aligned the evaluation of government portal website with new public administration principles so that government can provide better services to the users because new focuses of public administration bring new strategies for e-Government. The proposed framework emphasizes content, function, and construction of government portals. The validation analysis showed that the proposed evaluation framework is well fitted. 30 major cities’ government portal websites in China are evaluated. The results suggested China has implemented advanced e-Government services such as e-democracy but the performance of those services is not appreciated by the user very well

Digital Transformation, Operating Capacity and Firm Performance: Empirical Evidence from the Chinese Stock Market

In the context of the digital economy, digital technologies such as big data, artificial intelligence, cloud computing and so on continue to promote enterprise value creation. This paper takes the annual reports of listed companies in Shanghai and Shenzhen A-shares from 2015 to 2021 as the object, constructs digital transformation indexes based on Word2Vec machine learning technology, and empirically analyzes the relationship between digital transformation, enterprise operating capacity and company performance. The study finds that: the higher the degree of digital transformation, the stronger the operating capacity of enterprises; the improvement of enterprise operating capacity can significantly enhance company performance; digital transformation will strengthen the positive effect of operating capacity on company performance. The study's findings not only reveal the moderating role of digital transformation in the relationship between enterprise operating capacity and company performance but also provide theoretical and empirical evidence for a comprehensive and objective evaluation of the implementation effect of digital transformation. Keywords: digital transformation, operating capacity, company performance, text analysis DOI: 10.7176/EJBM/15-16-01 Publication date:September 30th 202