565 research outputs found
Exploiting Tradeoff Between Transmission Diversity and Content Diversity in Multi-Cell Edge Caching
Caching in multi-cell networks faces a well-known dilemma, i.e., to cache
same contents among multiple edge nodes (ENs) to enable transmission
cooperation/diversity for higher transmission efficiency, or to cache different
contents to enable content diversity for higher cache hit rate. In this work,
we introduce a partition-based caching to exploit the tradeoff between
transmission diversity and content diversity in a multi-cell edge caching
networks with single user only. The performance is characterized by the system
average outage probability, which can be viewed as the sum of the cache hit
outage probability and cache miss probability. We show that (i) In the low
signal-to-noise ratio(SNR) region, the ENs are encouraged to cache more
fractions of the most popular files so as to better exploit the transmission
diversity for the most popular content; (ii) In the high SNR region, the ENs
are encouraged to cache more files with less fractions of each so as to better
exploit the content diversity.Comment: Accepted by IEEE International Conference on Communications (ICC),
Kansas City, MO, USA, May 201
Content Placement in Cache-Enabled Sub-6 GHz and Millimeter-Wave Multi-antenna Dense Small Cell Networks
This paper studies the performance of cache-enabled dense small cell networks
consisting of multi-antenna sub-6 GHz and millimeter-wave base stations.
Different from the existing works which only consider a single antenna at each
base station, the optimal content placement is unknown when the base stations
have multiple antennas. We first derive the successful content delivery
probability by accounting for the key channel features at sub-6 GHz and mmWave
frequencies. The maximization of the successful content delivery probability is
a challenging problem. To tackle it, we first propose a constrained
cross-entropy algorithm which achieves the near-optimal solution with moderate
complexity. We then develop another simple yet effective heuristic
probabilistic content placement scheme, termed two-stair algorithm, which
strikes a balance between caching the most popular contents and achieving
content diversity. Numerical results demonstrate the superior performance of
the constrained cross-entropy method and that the two-stair algorithm yields
significantly better performance than only caching the most popular contents.
The comparisons between the sub-6 GHz and mmWave systems reveal an interesting
tradeoff between caching capacity and density for the mmWave system to achieve
similar performance as the sub-6 GHz system.Comment: 14 pages; Accepted to appear in IEEE Transactions on Wireless
Communication
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