LTE/WiFi coexistence in unlicensed bands by HLBT mechanism

With the growth of data demand in Long Term Evolution (LTE), licensed frequency bands are becoming increasingly crowded. Implementing LTE system to unlicensed frequency bands, called Licensed-Assisted Access (LAA), has been raised to solve the problem. However, there exist other wireless networks in the unlicensed bands, such as 802.11p system. LAA system needs to avoid interference with other wireless systems in the same frequency band. In this paper, Listen-Before- Talk (LBT) mechanism, which is raised to realize the coexistence between LAA system and WiFi system, has been simulated. Moreover, a novel hybrid LBT (HLBT) mechanism has been discussed and compared with LBT mechanism. HLBT mechanism includes two operating modes, which are designed for different channel situations, and switches between them adaptively. The simulation results illustrate that both LBT and HLBT mechanisms can make LAA system coexist with other systems, and HLBT mechanism performs better.