Distributed Resource Management in Downlink Cache-Enabled Multi-Cloud Radio Access Networks

In the scope of beyond fifth generation (B5G) networks and the massive increase of data-hungry systems, the need of extending conventional single-cloud radio access networks (C-RAN) arises. A compound of several clouds, jointly managing inter-cloud and intra-cloud interference, constitutes a practical solution to cope with requirements of B5G networks. This paper considers a multi-cloud radio access network model (MC-RAN) where each cloud is connected to a distinct set of base stations (BSs) via limited capacity fronthaul links. The BSs are equipped with local cache storage and baseband processing capabilities, as a means to alleviate the fronthaul congestion problem. The paper then investigates the problem of jointly assigning users to clouds and determining their beamforming vectors so as to maximize the network-wide energy efficiency (EE) subject to fronthaul capacity, and transmit power constraints. This paper solves such a mixed discrete-continuous, non-convex optimization problem using fractional programming (FP) and successive inner-convex approximation (SICA) techniques to deal with the non-convexity of the continuous part of the problem, and l0-norm approximation to account for the binary association part. A highlight of the proposed algorithm is its capability of being implemented in a distributed fashion across the network multiple clouds through a reasonable amount of information exchange. The numerical simulations illustrate the pronounced role the proposed algorithm plays in alleviating the interference of large-scale MC-RANs, especially in dense networks. Part of this paper was presented at the IEEE International Conference on Communications Workshops, June 2020 [1]. Alaa Alameer Ahmad, Robert-Jeron Reifert and Aydin Sezgin are with Digital Communication Systems, Ruhr-Universität Bochum, Bochum, Germany. (Email: {alaa.alameerahmad,robert-.reifert,aydin.sezgin}@rub.de) Hayssam Dahrouj, Tareq Y. Al-Naffouri and Mohamed-Slim Alouini are with King Abdullah University of Science and Technology, Thuwal, Saudi Arabia. (Email: {hayssam.dahrouj,tareq.alnaffouri,slim.alouini}@kaust.edu.sa) Anas Chaaban is with the School of Engineering, The University of British Columbia, Kelowna, Canada. (Email: anas.chaaban@ubc.ca) ar X iv :2 10 4. 03 66 4v 1 [ cs .I T ] 8 A pr 2 02 1

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