2,705 research outputs found
Hybrid Transceiver Optimization for Multi-Hop Communications
Multi-hop communication with the aid of large-scale antenna arrays will play
a vital role in future emergence communication systems. In this paper, we
investigate amplify-and-forward based and multiple-input multiple-output
assisted multi-hop communication, in which all nodes employ hybrid
transceivers. Moreover, channel errors are taken into account in our hybrid
transceiver design. Based on the matrix-monotonic optimization framework, the
optimal structures of the robust hybrid transceivers are derived. By utilizing
these optimal structures, the optimizations of analog transceivers and digital
transceivers can be separated without loss of optimality. This fact greatly
simplifies the joint optimization of analog and digital transceivers. Since the
optimization of analog transceivers under unit-modulus constraints is
non-convex, a projection type algorithm is proposed for analog transceiver
optimization to overcome this difficulty. Based on the derived analog
transceivers, the optimal digital transceivers can then be derived using
matrix-monotonic optimization. Numeral results obtained demonstrate the
performance advantages of the proposed hybrid transceiver designs over other
existing solutions.Comment: 32 pages, 6 figures. This manuscript has been submitted to IEEE
Journal on Selected Areas in Communications (special issue on Multiple
Antenna Technologies for Beyond 5G
Study of the effects of external imaginary electric field and chiral chemical potential on quark matter
The behavior of quark matter with both external electric field and chiral
chemical potential is theoretically and experimentally interesting to consider.
In this paper, the case of simultaneous presence of imaginary electric field
and chiral chemical potential is investigated using the lattice QCD approach
with dynamical staggered fermions. We find that overall both the
imaginary electric field and the chiral chemical potential can exacerbate
chiral symmetry breaking, which is consistent with theoretical predictions.
However we also find a non-monotonic behavior of chiral condensation at
specific electric field strengths and chiral chemical potentials. In addition
to this, we find that the behavior of Polyakov loop in the complex plane is not
significantly affected by chiral chemical potential in the region of the
parameters consider in this paper.Comment: 24 pages, 13 figure
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