An adaptive p-persistent CSMA scheme for LTE in unlicensed bands

With the exponential growth of wireless data demand and the increasing scarcity of licensed spectrum, mobile network operators are considering extending the use of Long Term Evolution (LTE) into the unlicensed spectrum to offload their traffic. In the future, it is very likely that LTE will coexist with WiFi on the same unlicensed bands, such as the Industrial, Scientific and Medical (ISM) bands. However, coexistence issues arise when the two technologies overlap with each other. Existing simulation results show that LTE is slightly impacted by such coexistence while WiFi performance is severely degraded. In order to improve LTE/WiFi coexistence, we propose an adaptive p-persistent Carrier Sense Multiple Access (CSMA) scheme for LTE in unlicensed bands. With the introduction of an additional factor to the conventional p-persistent CSMA scheme, the probability of LTE accessing the unlicensed channels is dynamically varied according to the interference measurements. Simulation results show that the proposed LTE adaptive p-persistent CSMA scheme can provide a flexible tradeoff between LTE and WiFi when they coexist with each other.