TY - Journal of Beijing University of Posts and Telecommunications A1 - PAN Zi-yu, YANG Jie T1 - Energy Efficiency Optimization for Ultra Dense Heterogeneous Cellular Networks Y1 - 2021-09-30 00:00:00.0 JF - Journal of Beijing University of Posts and Telecommunications JO - Journal of Beijing University of Posts and Telecommunications SP - 20 EP - 25,58 VL - 44 IS - 1 UR - {https://journal.bupt.edu.cn/EN/10.13190/j.jbupt.2020-052} N1 - 10.13190/j.jbupt.2020-052 ER -