Modeling and Analyzing the Coexistence of Wi-Fi and LTE in Unlicensed Spectrum

• Published in: IEEE transactions on wireless communications Vol. 15; no. 9; pp. 6310 - 6326
• Main Authors: Yingzhe Li, Baccelli, Francois, Andrews, Jeffrey G., Novlan, Thomas D., Zhang, Jianzhong Charlie
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.09.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Analytical models; Geometry; IEEE 802.11 Standard; Interference; licensed-assisted access; LTE in unlicensed; Protocols; Signal to noise ratio; stochastic geometry; Stochastic processes; Wi-Fi
• ISSN: 1536-1276; 1558-2248
• DOI: 10.1109/TWC.2016.2582866

We leverage stochastic geometry to characterize key performance metrics for neighboring Wi-Fi and LTE networks in unlicensed spectrum. Our analysis focuses on a single unlicensed frequency band, where the locations for the Wi-Fi access points and LTE eNodeBs are modeled as two independent homogeneous Poisson point processes. Three LTE coexistence mechanisms are investigated: 1) LTE with continuous transmission and no protocol modifications; 2) LTE with discontinuous transmission; and 3) LTE with listen-before-talk and random back-off. For each scenario, we derive the medium access probability, the signal-to-interference-plus-noise ratio coverage probability, the density of successful transmissions (DST), and the rate coverage probability for both Wi-Fi and LTE. Compared with the baseline scenario where one Wi-Fi network coexists with an additional Wi-Fi network, our results show that Wi-Fi performance is severely degraded when LTE transmits continuously. However, LTE is able to improve the DST and rate coverage probability of Wi-Fi while maintaining acceptable data rate performance when it adopts one or more of the following coexistence features: a shorter transmission duty cycle, lower channel access priority, or more sensitive clear channel assessment thresholds.