17,455 research outputs found
Beam Management for Millimeter Wave Beamspace MU-MIMO Systems
Millimeter wave (mmWave) communication has attracted increasing attention as
a promising technology for 5G networks. One of the key architectural features
of mmWave is the use of massive antenna arrays at both the transmitter and the
receiver sides. Therefore, by employing directional beamforming (BF), both
mmWave base stations (MBSs) and mmWave users (MUEs) are capable of supporting
multi-beam simultaneous transmissions. However, most researches have only
considered a single beam, which means that they do not make full potential of
mmWave. In this context, in order to improve the performance of short-range
indoor mmWave networks with multiple reflections, we investigate the challenges
and potential solutions of downlink multi-user multi-beam transmission, which
can be described as a high-dimensional (i.e., beamspace) multi-user
multiple-input multiple-output (MU-MIMO) technique, including multi-user BF
training, simultaneous users' grouping, and multi-user multibeam power
allocation. Furthermore, we present the theoretical and numerical results to
demonstrate that beamspace MU-MIMO compared with single beam transmission can
largely improve the rate performance of mmWave systems.Comment: The sixth IEEE/CIC International Conference on Communications in
China (ICCC2017
Hadronic Decays Involving Heavy Pentaquarks
Recently several experiments have reported evidences for pentaquark
. H1 experiment at HERA-B has also reported evidence for .
is interpreted as a bound state of an with other four light
quarks which is a member of the anti-decuplet under flavor .
While is a state by replacing the in by a . One can also form by replacing the by a . The
charmed and bottomed heavy pentaquarks form triplets and anti-sixtets under
. We study decay processes involving at least one heavy pentaquark
using and estimate the decay widths for some decay modes. We find
several relations for heavy pentaquarks decay into another heavy pentaquark and
a or a which can be tested in the future. can decay
through weak interaction to charmed heavy pentaquarks. We also study some
decay modes with a heavy pebtaquark in the final states. Experiments at the
current factories can provide important information about the heavy
pentaquark properties.Comment: RevTex 20 pages. Revised version. Discussions on the recent H1 data
and new references adde
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