关键词: 异构网络, 蝙蝠算法, 小区范围扩展（CRE）, 负载均衡

Abstract: The location of users in a two-tier cellular network including Macrocell and Femtocell is very random in the space domain and the time domain, which brings many challenges to resource allocation and interference management. To adapt to this random resource allocation, improve the communication speed of the cell edge users of the downlink heterogeneous cellular network in the same-frequency networking, and achieve a better load balancing effect, an improved bat algorithm is proposed to dynamically set the Femtocell Cell Range Expansion（CRE） offset value in real time, The  scheme  is used to relieve the high hot spot load pressure of the macro base station and incr- ease the network capacity, so that the user can reasonably choose to access different base stations, and the power resources can be reasonably used to achieve load balancing. The simulation results show that compared with the existing schemes, the proposed scheme improves the cell edge data rate and the energy efficiency, and achieves a better load sharing effect under the condition of Macrocell communication performance.

Key words: heterogeneous networks, bat algorithm, Cell Range Expansion（CRE）, load balancing