Open Access

ARTICLE

A Survey on Technologies and Challenges of LTE-U

by Tong Gan¹, Shi-You Wang¹, Qiang Ma¹, Yi-Dong Jia^2,*, Yun-Yun Ma³

1 Beijing Metro Consultancy Corporation Ltd., Beijing, 100071, China
2 School of Computer and Communication Engineering, University of Science and Technology Beijing, Beijing, 100083, China
3 School of Electronic Electrical and Systems Engineering, University of Birmingham, Birmingham, B15 2TT, United Kingdom

* Corresponding Author: Yi-Dong Jia. Email:

Computer Systems Science and Engineering 2022, 41(1), 321-337. https://doi.org/10.32604/csse.2022.019244

Received 07 April 2021; Accepted 01 June 2021; Issue published 08 October 2021

Abstract

The rapid growth of mobile data traffic has caused great pressure on the limited spectrum resources, and there must be some better methods to deal with this problem. The innovative technology of Long-Term Evolution (LTE) using the unlicensed spectrum, known as LTE-Unlicensed (LTE-U), has been proposed to effectively alleviate the shortage of authorized band resources. LTE-U has explored a lot of potential capacity in mobile communication systems with limited authorized spectrum resources, and improved the spectrum utilization of unauthorized frequency bands. However, LTE-U is still facing challenges in its application. In this paper, we summarize the key features of LTE-U and the coexistence of LTE-U with Wi-Fi in the unlicensed Spectrum. We analyze the key technologies (including carrier aggregation, HARQ, interference cancelation, and centralized scheduling), the operating modes and deployment scenarios (including carrier aggregation LTE-U, duty cycle LTE-U, and standalone LTE-U), and the advantages (including anchored LTE-U and Standalone LTE-U scenarios), as well as main technical challenges. We then address the different management mechanisms of LTE-U and Wi-Fi (including the differences between the MAC layer and physical layer), the types of coexistence technology classification (including channel separation and channel sharing technologies), and directions for future work. We hope that this comprehensive survey spurs further research in this promising area.

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Keywords

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