Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Coverage and Capacity of Ultra-Dense Networks with Directional
  Transmissions   We investigate the performance of a downlink ultra-dense network (UDN) with
directional transmissions via stochastic geometry. Considering the dual-slope
path loss model and sectored beamforming pattern, we derive the expressions and
asymptotic characteristics of the coverage probability and constrained area
spectrum efficiency (ASE). Several special scenarios, namely the physically
feasible path loss model and adjustable beam pattern, are also analyzed.
Although signal-to-interference-plus-noise ratio collapsing still exists when
the path loss exponent in the near-field is no larger than 2, using strategies
like beam pattern adaption, can avoid the decrease of the coverage probability
and constrained ASE even when the base station density approaches infinity.

31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom
10
The categories of this paper are: q-bio
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org
13
The categories of this paper are: quant-ph