Performance Analysis of Millimeter Wave Massive MIMO Systems in Centralized and Distributed Schemes

This paper considers downlink multi-user millimeter-wave massive multiple-input multiple-output (MIMO) systems in both centralized and distributed configurations, referred to as C-MIMO and D-MIMO, respectively. Assuming the fading channel is composite and comprised of both large-scale fading and small-scale fading, a hybrid precoding algorithm leveraging antenna array response vectors is applied into both the C-MIMO system with fully connected structure and the D-MIMO system with partially connected structure. First, the asymptotic spectral efficiency (SE) of an arbitrary user and the asymptotic average SE of the cell for the C-MIMO system are analyzed. Then, two radio access unit (RAU) selection algorithms are proposed for the D-MIMO system, based on minimal distance (D-based) and maximal signal-to-interference-plus-noise-ratio (SINR) (SINR-based), respectively. For the D-MIMO system with circular layout and D-based RAU selection algorithm, the upper bounds on the asymptotic SE of an arbitrary user and the asymptotic average SE of the cell are also investigated. Finally, numerical results are provided to assess the analytical results and evaluate the effects of the numbers of total transmit antennas and users on system performance. It is shown that, from the perspective of the cell, the D-MIMO system with D-based scheme outperforms the C-MIMO system and achieves almost alike performance compared with the SINR-based solution while requiring less complexity.Peer reviewe

Average transmit power of adaptive ZF very large multi-user and multi-antenna systems

This document is the Accepted Manuscript version of the following article: Dian-Wu Yue, and Yichuang Sun, ‘Average Transmit Power of Adaptive ZF Very Large Multi-user and Multi-antenna Systems’, Wireless Personal Communications, Vol. 81 (3): 1215-1232, April 2015. The final publication is available at Springer via https://doi.org/10.1007/s11277-014-2180-6.In this paper, we investigate adaptive zero-forcing uplink transmission for very large multi-user multi-antenna systems in Rayleigh fading environments. We assume that the number of antennas at the base station (denoted as $$M$$M) is not less than the number of users (denoted as $$K$$K) with each having single antenna, and power control can be done at the transmitter(s) as channel condition changes. Under constraints of individual rates and maximum transmit powers, we adopt the optimal transmit strategy of minimizing the total average transmit power (ATP). We derive and give individual ATP expressions for each link with short- and long-term rate constraints, respectively. Numerical results show that the individual ATP for each link with short term rate constraint is quite close to its long term counterpart when $$M-K$$M-K is large, and its corresponding outage probability can be designed to be nearly zero at the same time. Finally, we present two simple adaptive transmission schemes with constant transmit power satisfying short- and long-term rate constraints, respectively. Both of them are easy to implement, and asymptotically optimal when $$M-K$$M-K grows without bound.Peer reviewe

Higher bottom and bottom-strange mesons

Motivated by the recent observation of the orbital excitation $B(5970)$ by CDF collaboration, we have performed a systematical study of the mass spectrum and strong decay patterns of the higher $B$ and $B_s$ mesons. Hopefully the present investigation may provide valuable clues to further experimental exploration of these intriguing excited heavy mesons.Comment: 13 pages, 11 figures, 10 tables. More discussions and references added. Accepted by Phys. Rev.

Non-strange partner of strangeonium-like state Y(2175)

Inspired by the observed Y(2175) state, we predict its non-strange partner Y(1915), which has a resonance structure with mass around 1915 MeV and width about $317\sim 354$ MeV. Experimental search for Y(1915) is proposed by analyzing the $\omega f_0(980)$ or $\omega \pi\pi$ invariant mass spectrum of the $e^+e^-\to \omega f_0(980), \omega \pi\pi$ and $J/\psi\to \eta \omega f_0(980)$ processes, which are accessible at Belle, BaBar, BESIII and forthcoming BelleII. Considering similarity between two families, the comparison of the mass spectra of $\omega$ and $\phi$ families can provide important information on the 1D state of $\phi$ family, $\phi(1910)$, which has a very broad resonance structure with mass around 1910 MeV regarded as the strangeonium partner of $\omega(1650)$. This also answers the question why the 1D state $\phi(1910)$ is still missing in experiment. This is supported by our former study on the properties of Y(2175), which explains Y(2175) as the 2D strangeonium because our theoretical total width is comparable with the Belle data.Comment: 5 pages, 5 figures. More discussions and numerical results added. Typos correcte