비면허대역 LTE-면허지원접속에서 멀티캐리어 Listen Before Talk 기법들의 공존성 연구

Licensed-Assisted Access (LAA) is the new feature of 3GPP Long-Term Evolution (LTE) that utilizes unlicensed bands as a means of providing additional bandwidth to aggregate. An important consideration for LTE’s operation in unlicensed spectrum is to guarantee fair coexistence with other incumbent systems such as Wi-Fi and other LAA cells/users. For this purpose, LAA’s Clear Channel Assessment (CCA) has been designed based on Listen-before-Talk (LBT) and verified to support fair access with Wi-Fi through extensive simulation studies. However, coexistence between different LBT options for multi-carrier operation has not been studied yet.
Since different LAA operators may use individual LBT options, their coexistence could also be a serious issue.
In this paper, we study the coexistence problem of different LBT options available for multi-carrier operation in unlicensed bands through extensive simulation in terms of system throughput, channel occupancy rate and delay.