With the exponential growth of wireless data traffic and the increasing scarcity of licensed spectrum, mobile network operators intend to use the unlicensed spectrum, such as the Industrial, Scientific and Medical (ISM) bands and TV white space, to offload their traffic. In the future, it is very likely that two of the most prominent wireless technologies, Long Term Evolution (LTE) and WiFi, will coexist on the same unlicensed bands. Existing simulation results show that LTE is slightly impacted by such coexistence while WiFi is severely hampered by LTE transmissions. In order to realize a harmonious LTE/WiFi coexistence, we propose two channel sensing schemes for LTE in unlicensed bands, i.e., periodic sensing and persistent sensing. Simulation results show that the proposed channel sensing schemes can provide a reasonable tradeoff between LTE and WiFi when they coexist with each other.