Adaptive Spectrum Sharing of LTE Co-Existing with WLAN in Unlicensed Frequency Bands With the increase of wireless communication demands, licensed spectrum for long term evolution (LTE) is no longer enough. The research effort has focused on implementing LTE to unlicensed frequency bands in recent years, which unavoidably brings the problem of how to make LTE co-exist with other existing systems on the same band. This paper proposes an adaptive co- existence mechanism forLTE and wireless local area networks (WLAN) to enable a significant system performance of WLAN while LTE does not lose much as well. LTE realizes the co-existence by allocating time resources dynamically according to the traffic load of WLAN system.