Simple Decentralized Cell Association Method for Heterogeneous Networks in Fading Channel

This paper proposes an extension to our previously reported simple decentralized cell association method for heterogeneous networks, where low transmission-power pico or femto base stations (BSs) overlay onto a high transmission-power macro BS, to accommodate the effects from a fading channel and proportional fair (PF)-based scheduling. The focus of this investigation is on the downlink and the purpose of the cell association is to increase the minimum user throughput (worst user throughput). In the proposed method, appropriate cell association for all users within a cell is achieved in an iterative manner based on the feedback information of each individual user regarding the throughput gain by connecting a new BS assisted by a small amount of broadcast information from the respective BSs regarding the allowable resource allocation and multiuser diversity gain. The proposed method does not require cooperation between BSs. The proposed method can be applied to the case with inter-cell interference coordination (ICIC) through the use of protected radio resources exclusively used by the pico/femto BSs. Based on numerical results, we show that the proposed method adaptively achieves better cell association for all users according to the user location distributions compared to the conventional cell range expansion (CRE) method. The advantage of the proposed method over CRE is further enhanced in an ICIC scenario.