Non‐best user association scheme and effect on multiple tiers heterogeneous networks

A novel m th best average biased received power (ABRP) user association (UA) scheme is proposed for K ‐tier heterogeneous networks, where a user is associated with the closest base station (BS) of the k th tier having the m th strongest ABRP, k + 1 , 2 , … , K . By using stochastic geometry and Poisson point processes, the authors perform the analysis of the UA probability that a typical user is associated with a BS that has the m th strongest ABRP as well as the downlink signal‐to‐interference‐noise ratio (SINR) coverage performance. The obtained results show that, for a given tier k , when the layer's position in the ordered set of ABRPs is not equal to m and the powerP kor densityλ kof BSs is relatively small, i.e.,P k < P i ( λ k < λ i ) , i ≠ k , the UA probability A k mm > 1increases monotonically withP korλ k . Contrarily, it decreases. For the other UA probabilities, the opposite results are achieved. Additionally, the results also show that the coverage probability of the downlink SINR of the tier k always increases with powerP k , which is consistent with the one in the conventionally best ABRP scheme. However, for other tiers, the corresponding downlink SINR coverage probabilities do not behave monotonically with the powerP k .