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http://dx.doi.org/10.7471/ikeee.2019.23.1.91

Narrowband Listen-Before-Talk under Coexistence with Wideband Systems in Unlicensed Spectrum  

Murti, Wisnu (Dept. of Electrical and Information Engineering and the Research Center for Electrical and Information Technology, Seoul National University of Science and Technology)
Yun, Ji-Hoon (Dept. of Electrical and Information Engineering and the Research Center for Electrical and Information Technology, Seoul National University of Science and Technology)
Publication Information
Journal of IKEEE / v.23, no.1, 2019 , pp. 91-98 More about this Journal
Abstract
LTE's extension for unlicensed spectrum called Licensed Assisted Access (LAA) is equipped with Listen-Before-Talk (LBT) designed similar with the backoff mechanism of Wi-Fi for coexistence. However, Wi-Fi's backoff mechanism has not evolved from its old design for compatibility with legacy devices, thus LAA's LBT is not efficient either in utilizing spectrum. If LAA operates with no Wi-Fi systems in proximity, it can run more efficient LBT. In this paper, we propose Narrowband Clear Channel Assessment (NCCA) for narrowband transmission. In NCCA, an LAA node performs LBT in either wide or each narrow bandwidth segment. This allows multiple LAA nodes to perform simultaneous transmissions in orthogonal bandwidth segments in the same time slot. We design four variants of NCCA implementation and model their performance using a mathematical model. The coexistence performance of NCCA with conventional wideband nodes and the accuracy of the model are shown via simulation.
Keywords
Licensed assisted access; listen-before-talk; clear channel assessment; unlicensed spectrum; LTE;
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