282 research outputs found

    Value Finance Theory

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    With the development of digital economy, metaverse and blockchain, the inherent economic form changes. In the era of digital economy, changes in value have new characteristics. This paper uses the method of political economy to analyze and demonstrate the composition of value. Then it analyzes the economic reasons for the economic depression, insufficient consumption power and unsalable commodities in the digital economy period. And the article gives a specific solution. It has specific application value for all countries to deal with and pass through the economic depression. It has a theoretical guiding role in the stable development of macro economy in the digital economy period

    Channel Estimation for mmWave Massive MIMO Based Access and Backhaul in Ultra-Dense Network

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    Millimeter-wave (mmWave) massive MIMO used for access and backhaul in ultra-dense network (UDN) has been considered as the promising 5G technique. We consider such an heterogeneous network (HetNet) that ultra-dense small base stations (BSs) exploit mmWave massive MIMO for access and backhaul, while macrocell BS provides the control service with low frequency band. However, the channel estimation for mmWave massive MIMO can be challenging, since the pilot overhead to acquire the channels associated with a large number of antennas in mmWave massive MIMO can be prohibitively high. This paper proposes a structured compressive sensing (SCS)-based channel estimation scheme, where the angular sparsity of mmWave channels is exploited to reduce the required pilot overhead. Specifically, since the path loss for non-line-of-sight paths is much larger than that for line-of-sight paths, the mmWave massive channels in the angular domain appear the obvious sparsity. By exploiting such sparsity, the required pilot overhead only depends on the small number of dominated multipath. Moreover, the sparsity within the system bandwidth is almost unchanged, which can be exploited for the further improved performance. Simulation results demonstrate that the proposed scheme outperforms its counterpart, and it can approach the performance bound.Comment: 6 pages, 5 figures. Millimeter-wave (mmWave), mmWave massive MIMO, compressive sensing (CS), hybrid precoding, channel estimation, access, backhaul, ultra-dense network (UDN), heterogeneous network (HetNet). arXiv admin note: substantial text overlap with arXiv:1604.03695, IEEE International Conference on Communications (ICC'16), May 2016, Kuala Lumpur, Malaysi

    Supply and Demand, Tax, Income, Profit and Proof of Goldbach’s Conjecture——Logic is the Basis of Correct Mathematical Measurement

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    This paper demonstrates that Marshall’s logic on the supply and demand curve is not rigorous enough, that Coase’s theorem is flawed, and that the “Okishio Theorem” and Sweezy s logic are inadequate through empirical proof. By the way, the Goldbach conjecture is proved through clever mathematical proof. It shows that beautiful curves and mathematical formulas cannot be separated from reality and logic, and correct logic can play a correct role in market theory. In this paper, the analysis of the actual supply and demand curve, as well as the concepts and models of tax, profit rate and income, has positive practical significance for economic depression and stagflation

    A novel uplink multiple access scheme based on TDS-FDMA

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    This contribution proposes a novel time-domain synchronous frequency division multiple access (TDS-FDMA) scheme to support multi-user uplink application. A unified frame structure for both single-carrier and multi-carrier transmissions and the corresponding low-complexity receiver design are derived. Compared with standard cyclic prefix based orthogonal frequency division multiple access systems, the proposed TDSFDMA scheme improves the spectral efficiency by about 5% to 10% as well as imposes a similarly low computational complexity, while obtaining a slightly better bit error rate performance over Rayleigh fading channels

    Channel Estimation for Millimeter-Wave Massive MIMO with Hybrid Precoding over Frequency-Selective Fading Channels

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    Channel estimation for millimeter-wave (mmWave) massive MIMO with hybrid precoding is challenging, since the number of radio frequency (RF) chains is usually much smaller than that of antennas. To date, several channel estimation schemes have been proposed for mmWave massive MIMO over narrow-band channels, while practical mmWave channels exhibit the frequency-selective fading (FSF). To this end, this letter proposes a multi-user uplink channel estimation scheme for mmWave massive MIMO over FSF channels. Specifically, by exploiting the angle-domain structured sparsity of mmWave FSF channels, a distributed compressive sensing (DCS)-based channel estimation scheme is proposed. Moreover, by using the grid matching pursuit strategy with adaptive measurement matrix, the proposed algorithm can solve the power leakage problem caused by the continuous angles of arrival or departure (AoA/AoD). Simulation results verify that the good performance of the proposed solution.Comment: 4 pages, 3 figures, accepted by IEEE Communications Letters. This paper may be the first one that investigates the frequency selective fading channel estimation for mmWave massive MIMO systems with hybrid precoding. Key words: Millimeter-wave (mmWave) massive MIMO, frequency-selective fading, channel estimation, compressive sensing, hybrid precodin
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