MPSO-based power adjustment and user association algorithm for energy efficiency in LTE heterogeneous networks

In this paper, we study the energy efficiency problem of the heterogeneous network composed of pico clusters deployed within the macro cells. We would like to find the optimal transmit power of the pico cells such that the energy efficiency of the cluster is the largest. A cell-specific cell selection bias is also considered so that each user may choose its serving cell in the most energy-efficient way. An energy efficient modified particle swarm optimization (MPSO)-based power allocation and user association algorithm is proposed that determines the transmit power and cell-selection bias for the picos in each macro cell. We present through simulation results the performance gain of the algorithm in terms of energy efficiency and spectrum efficiency over the spectral-efficient MPSO-based power adjustment algorithm and the maximum transmit power allocation scheme. Compared with the traditional user association scheme of maximum reference signal received power, we demonstrate the advantage of considering cell-selection bias in our algorithm.