Fair co-existence of Licensed Assisted Access LTE (LAA-LTE) and Wi-Fi in unlicensed spectrum

Continued growth in wireless data demands has driven the need for more spectrum. Both licensed and unlicensed spectrum solutions are being deployed and viewed as complementary in dealing with the wireless traffic explosion. For example, Wi-Fi is being used successfully to assist in offloading the more spectrally constrained licensed band systems. At the heart of Wi-Fi's success is the premise of fair co-existence so that multiple Wi-Fi system owners can deploy Wi-Fi access points in the same unlicensed spectrum in an unmanaged fashion. Given Wi-Fi's success, the idea of leveraging unlicensed spectrum with LTE is being proposed through a feature called Licensed Assisted Access (LAA-LTE). This paper reports our findings in designing LBT mechanisms for LAA-LTE to ensure that it operates at least as fairly as Wi-Fi in unlicensed spectrum. These findings are based on our simulation results of co-existence performance between LAA-LTE and Wi-Fi for different candidate LBT schemes as reported in this paper. It concludes that for fair co-existence LBT is essential for LAA-LTE, but also that the choice of LBT scheme and settings of that scheme matter, with those proposed in current European regulations likely to result in Wi-Fi being disadvantaged.