Two key traits of 5G cellular networks are much higher base station (BS)densities - especially in the case of low-power BSs - and the use of massiveMIMO at these BSs. This paper explores how massive MIMO can be used to jointlymaximize the offloading gains and minimize the interference challenges arisingfrom adding small cells. We consider two interference management approaches:joint transmission (JT) with local precoding, where users are servedsimultaneously by multiple BSs without requiring channel state informationexchanges among cooperating BSs, and resource blanking, where some macro BSresources are left blank to reduce the interference in the small cell downlink.A key advantage offered by massive MIMO is channel hardening, which enables topredict instantaneous rates a priori. This allows us to develop a unifiedframework, where resource allocation is cast as a network utility maximization(NUM) problem, and to demonstrate large gains in cell-edge rates based on theNUM solution. We propose an efficient dual subgradient based algorithm, whichconverges towards the NUM solution. A scheduling scheme is also proposed toapproach the NUM solution. Simulations illustrate more than 2x rate gain for10th percentile users vs. an optimal association without interferencemanagement.
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