Coexistence algorithms for LTE and WiFi networks in unlicensed spectrum: performance optimization and comparison

Facing the challenges brought by the surge in the demand for mobile data traffic, many coexistence algorithms for long-term evolution (LTE) and WiFi networks in the unlicensed spectrum have been developed recently. In this article, we investigate, optimize, and compare several solutions to operate LTE in the unlicensed band, which include duty-cycle muting (DCM) mechanism, listen-before-talk (LBT) mechanism, and LTE and WLAN aggregation (LWA) algorithm. We first overview the architecture, working mechanism, coexistence problem with WiFi network, and overall cost of the three different coexistence mechanisms. Their advantages and disadvantages are also compared and analyzed in detail. Then, to maximize the spectrum efficiency of unlicensed band, we optimize the corresponding adjustable variables in the three algorithms. Furthermore, numerical simulations are conducted to compare the performances of DCM, LBT, and LWA explicitly. The results show that DCM can achieve the highest throughput for the LTE network while LBT and LWA have less impact on the WiFi system.