부산대학교 도서관

Heterogeneous networks (HetNets) are considered as a standard part of the future generation of wireless networks where masses of low power, low cost smallcells (e.g., femtocells) are anticipated to support the existing macrocell networks. While HetNets are increasing the spectral efficiency and decreasing the over-the-air signaling and uplink power consumption compared to macro networks, the large scale deployment of many lightly loaded smallcells is expected to increase the downlink power consumption of the HetNets. This paper studies the impact of smallcell population on the downlink power consumption of the HetNets. In this context, we propose that the population of smallcells is strictly depending on the traffic load due to active mobile users, which is a random variable and time-varying. We derive the mathematical framework to calculate the required population of smallcells based on the probabilistic traffic models where the number of total mobile users and number of active mobile users have different probabilistic distributions such as different combinations of Binomial and Poisson distributions. The proposed method guarantees the reduction in downlink power consumption of HetNets by forcing the smallcells to turn on the sleeping mode under low and medium traffic load conditions. Several simulation results are included to illustrate the impact of traffic load dependent population of smallcells on the downlink power consumption of HetNets. Moreover, it is shown that the mathematical and simulation results are in perfect agreement.