Hongli He Hangguan Shan Aiping Huang Lin X. Cai Tony Q. S. Quek Proportional Fairness-Based Resource Allocation for LTE-U Coexisting With Wi-Fi. 4720-4731 2017 5 IEEE Access https://doi.org/10.1109/ACCESS.2016.2604822 db/journals/access/access5.html#HeSHCQ17