Joint Optimization for User Association and Inter-Cell Interference Coordination Based on Proportional Fair Criteria in Small Cell Deployments

Nobuhiko MIKI  Yusaku KANEHIRA  

Publication
IEICE TRANSACTIONS on Communications   Vol.E103-B   No.3   pp.253-261
Publication Date: 2020/03/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2019EBP3040
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
Keyword: 
small cell,  user association,  interl-cell Interference coordination (ICIC),  Karush-Huhn-Tucher (KKT) conditions,  proportional fair criteria,  

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Summary: 
In small cell deployments, the combined usage of user association and inter-cell interference coordination (ICIC) is inevitable. This paper investigates the joint optimization of user association and ICIC in the downlink. We first formulate the joint optimization problem as a utility maximization problem. We then employ the logarithmic utility function known as the proportional fair criteria. The optimum user association and the ICIC are derived by solving a convex optimization problem based on the average spectral efficiencies of all users. We propose an iterative algorithm to obtain the optimum solution to this problem. We evaluate the performance of the proposed algorithm for the small cell deployments and shows that the proposed algorithm works well. We also compare the performance of the proposed algorithm based on utility maximization user association with the CRE, and show the superiority of the utility maximization. Furthermore, we show that intra-tier ICIC and inter-tier ICIC can effectively improve the throughput performance according to the conditions. It is also shown that the combined usage of inter-tier ICIC and intra-tier ICIC enhances the throughput performance compared to schemes employing either the inter- or intra-tier ICIC scheme.