Abstract
This paper considers a content-centric fog radio
access network (F-RAN). Its multi-antenna remote radio heads
(RRHs) are capable of caching and executing signal processing
for content delivery to its users. The fronthaul traffic is thus saved
since its baseband processing unit (BBU) needs to transfer only
the cache-missed content items to the RRHs via limited-capacity
fronthaul links. The problem of beamforming design maximizing
the energy efficiency in content delivery subject to the qualityof-content-service constraints in terms of content throughput
and fronthaul limited-capacity is addressed. Unlike the user’s
throughput in user-centric networks, the content throughput in
content-centric networks is no longer a differentiable function
of the beamforming vectors. The problem is inherently highdimensional due to the involvement of many beamforming vectors
even in simple cases of three RRHs serving three users. Pathfollowing algorithms, which invoke a simple convex quadratic
optimization problem to generate a better feasible point, are proposed for computation of this nonsmooth and high-dimensional
optimization problem. We also employ the generalized zeroforcing beamforming, which forces the multi-content interference
to zero or nearly to zero to reduce the problem dimensionality for
computational efficiency. The numerical results are provided to
demonstrate their computational effectiveness. They also reveal
that when the fronthaul traffic becomes more flexible, the hardtransfer fronthauling is more energy efficient than the softtransfer fronthauling.
Original language | English |
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Journal | IEEE Transactions on Signal Processing |
Early online date | 06 Jan 2020 |
DOIs | |
Publication status | Early online date - 06 Jan 2020 |