Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Secure and Energy-Efficient Transmissions in Cache-Enabled Heterogeneous
  Cellular Networks: Performance Analysis and Optimization   This paper studies physical-layer security for a cache-enabled heterogeneous
cellular network comprised of a macro base station and multiple small base
stations (SBSs). We investigate a joint design on caching placement and file
delivery for realizing secure and energy-efficient transmissions against
randomly distributed eavesdroppers. We propose a novel hybrid "most popular
content" and "largest content diversity" caching placement policy to distribute
files of different popularities. Depending on the availability and placement of
the requested file, we employ three cooperative transmission schemes, namely,
distributed beamforming, frequency-domain orthogonal transmission, and best SBS
relaying, respectively. We derive analytical expressions for the connection
outage probability and secrecy outage probability for each transmission scheme.
Afterwards, we design the optimal transmission rates and caching allocation
successively to achieve a maximal overall secrecy throughput and secrecy energy
efficiency, respectively. Numerical results verify the theoretical analyses and
demonstrate the superiority of the proposed hybrid caching policy.

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The categories of this paper are: cond-mat
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The categories of this paper are: hep-lat
13
The categories of this paper are: quant-ph
35
The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
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The categories of this paper are: solv-int
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The categories of this paper are: dg-ga