Recently, an evolution of the Cloud Radio Access Network (C-RAN) has beenproposed, named as Fog Radio Access Network (F-RAN). Compared to C-RAN, theRadio Units (RUs) in F-CAN are equipped with local caches, which can store somefrequently requested files. In the downlink, users requesting the same fileform a multicast group, and are cooperatively served by a cluster of RUs. Therequested file is either available locally in the cache of this cluster orfetched from the Central Processor (CP) via backhauls. Thus caching somefrequently requested files can greatly reduce the burden on backhaul links.Whether a specific RU should be involved in a cluster to serve a multicastgroup depends on its backhaul capacity, requested files, cached files and thechannel. Therefore it is subject to optimization. In this paper we investigatethe joint design of multicast beamforming, dynamic clustering and backhaultraffic balancing. Beamforming and clustering are jointly optimized in order tominimize the power consumed, while QoS of each user is to be met and thetraffic on each backhaul link is balanced according to its capacity.
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