LTE-LAA and WiFi in 5G NR Unlicensed: Fairness, Optimization and Win-Win Solution
Yayu Gao · 2019
LTE Licensed Assisted Access (LTE-LAA) has been considered as a promising solution for harmonious coexistence with WiFi in the 5G NR Unlicensed. In this paper, we study the open question of how to adaptively tune system parameters to maximize the total network sum rate with the prerequisite that the 3GPP notion of fairness is guaranteed between LAA and WiFi in LTE-WiFi-coexisting networks. Explicit expressions of the maximum network sum rate and the corresponding optimal initial backoff window sizes of WiFi nodes and LAA UEs are obtained, and verified by simulation results. The analysis further shows that there exists a win-win solution for LAA design, where not only the 3GPP fairness can always be maintained, but the new-installed LTE-WiFi coexisting network can outperform a legacy WiFi network as well. To achieve it, the transmission opportunity (TXOP) of LAA needs to exceed a certain threshold. The analysis provides direct guidance for network optimization and protocol design for LTE-LAA and WiFi coexistence.