Joint Spectrum-Sharing and Base Station Sleep Model for Improving Energy Efficiency of Heterogeneous Networks

A joint optimization method taking into account both the partial spectrum reuse (PSR) scheme and the base station sleep (BSS) model is proposed for improving the energy efficiency of heterogeneous networks (HetNets). In this paper, the coverage probabilities for both the macrotier and microtier networks are derived, followed by maximizing the coverage probability of the HetNets conceived for optimizing both the PSR factor and macro-microbase station's (BS) active probability ratio (APR). Furthermore, the problem of energy consumption minimization in HetNets can be addressed by analyzing the relationship between the optimal PSR factor and APR. Numerical results show that, under both the closed-access strategy and interference-limited case, and additionally by setting the signal to interference and noise ratio target to be 20 dB, the energy consumption of up to 50% in a two-tier HetNet can be saved by invoking the proposed joint optimization method, without eroding the average ergodic rate, provided that the macrocell BS (macroBS) transmit power is as high as five times that of the microcell BSs (microBSs).