Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: MIMO Underlay Cognitive Radio: Optimized Power Allocation, Effective
  Number of Transmit Antennas and Harvest-Transmit Tradeoff   In this paper, the performance of an underlay multiple-input multiple-output
(MIMO) cognitive radio system is analytically studied. In particular, the
secondary transmitter operates in a spatial multiplexing transmission mode,
while a zero-forcing detector is employed at the secondary receiver.
Additionally, the secondary system is interfered by single-antenna primary
users (PUs). To enhance the performance of secondary transmission, optimal
power allocation is performed at the secondary transmitter with a constraint on
the maximum allowable outage threshold specified by the PUs. Further, the
effective number of secondary transmit antennas is specified based on the
optimal power allocation for an arbitrary MIMO scale. Also, a lower bound on
the ergodic channel capacity of the secondary system is derived in a
closed-form expression. Afterwards, the scenario of a massive MIMO secondary
system is thoroughly analyzed and evaluated, where the harvesting-enabled
secondary transmission is studied. The optimal power allocation, the effective
number of secondary transmit antennas, the efficient tradeoff between
transmit-and-harvest secondary antennas, and the average channel capacity of
the secondary system are analytically presented. Finally, extensive numerical
and simulation results corroborate the effectiveness of our analysis, while
some useful engineering insights are provided.

12
The categories of this paper are: nucl-th
19
The categories of this paper are: eess
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas
36
The categories of this paper are: cmp-lg
20
The categories of this paper are: acc-phys
35
The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
6
The categories of this paper are: astro-ph