Decoupled uplink-downlink association for finite multi-tier networks

A decoupled association scheme is considered based on instantaneous received power in downlink and uplink. Unlike traditional cellular networks where the associated base stations (BSs) in downlink and uplink are the same, in decoupled association the associated BSs in uplink and downlink can be different. The probability of user associations in co-channel BSs in finite multi-tier networks (with finite number of BSs) are derived for both uplink and downlink cases. In this paper, the wireless channel is modeled as large-scale fading and small-scale fading, and the transmit power, path loss exponent and bias factor for each BS are different. Based on probability of user associations derived for uplink and downlink, an efficient decoupled association scheme is proposed where the BS with highest probability of user association is selected as the serving BS. Simulation results confirm the superiority of this scheme over conventional approach to user association.