Wi-Fi and LTE-LAA coexistence problems, challenges and features in 5GHz unlicensed bandwidth

The demand for high data rate and stable Quality of Service (QoS) from cellular networks’ subscribers is a huge challenge for cellular operators. To overcome this issue (providing high data rate and stable QoS) it requires more bandwidth. The lack of licensed bandwidth and also its high cost make it hard for operators to overcome this issue. To find a fair solution and expand the capacity of cellular networks, operators started deployment of Long Term Evolution (LTE) in unlicensed bandwidth, exactly utilizing 5GHz unlicensed bandwidth in small cell scenarios. The extension of LTE to the 5GHz unlicensed bandwidth where it is already in used by Wi-Fi will create huge coexistence problems between Wi-Fi and LTE. It results from that Wi-Fi and LTE have different channel access mechanisms. This paper presents the channel access mechanisms of Wi-Fi and LTE-Licensed Assisted Access (LTE-LAA), coexistence problems, challenges, privileges, coexistence features of LTE and Wi-Fi and Finally, we conducted the simulation for LAA based on Listen Before Talk (LBT) mechanism and Wi-Fi to find that how LAA with LBT mechanism is friendly to the Wi-Fi networks when they share the same bandwidth. The simulation results illustrate that LAA based on LBT channel access mechanism by alone cannot bring a fair coexistence between these two technologies, it needs further improvement.

Keywords:

LTE, LTE-LAA, Wi-Fi, Coexistence, LBT CSMA/CA, performance,

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[1] N. R. a. I. Guvenc, "Licensed-Assisted Access for WiFi-LTE Coexistence in the Unlicensed Spectrum," IEEE, pp. 1-6, 2014. [2] J. A.-F. B. H. Alireza Babaei, "On the Impact of LTE-U on Wi-Fi Performance," IEEE, vol. 1, no. 978, pp. 1-5, 2014. [3] Qualcomm, "Progress on LAA and its relationship to LTE-U and MulteFire," Qualcomm Technologies, 2016.[4] R. v. Steve, Wireless Networking Technology, UK: Newnes, 2007. [5] S. K. F. H. John D. Matyjas, Spectrum Sharing in Wireless Networks, Florida: CRC Press, 2016. [6] Devid, Certified Wireless Network Administrator, Indiana: Sybex, 2014.[7] Qualcomm, "Progress on LAA and its relationship to LTE-U and MulteFire," Qualcomm, 2016.[8] Qualcomm, "Progress on LAA and its relationship to LTE-U and MulteFire," Qualcomm, 25 Feb 2016. [Online]. Available: https://www.qualcomm.com/documents/progress-laa-and-its-relationship-lte-u-and-multefire. [Accessed 23 May 2018].[9] A. C. C. V. P. S. C. T. D. Abinader, "Enabling the Coexistence of LTE and Wi-Fi in Unlicensed Bands," IEEE, vol. 52, no. 11, pp. 54-61, 2014. [10] K. T. L. F. Sadek, "Extending LTE to Unlicensed Band – Merit and Coexistence," IEEE, pp. 1-6, 2015. [11] J. a. Wannstrom, "Carrier Aggregation explained," 3GPP, 16 June 2013. [Online]. Available:http://www.3gpp.org/technologies/keywords-acronyms/101-carrier-aggregation-explained. [Accessed 24 10 2018].[12] P. a. Ian, "LTE CA: Carrier Aggregation Tutorial," Radio-electronics, 18 11 2017. [Online]. Available: https://www.radio-electronics.com/info/cellulartelecomms/lte-long-term-evolution/4g-lte-advanced-carrier-channel-aggregation.php. [Accessed 23 10 2018].[13] C. Cox, An Introduction to LTE, UK: WILEY, 2014. [14] L. a. pedrini, "What is Retransmission, ARQ and HARQ?," telecomehall, 22 June 2012. [Online].Available:http://www.telecomhall.com/what-is-retransmission-arq-and-harq.aspx. [Accessed 15 9 2018].[15] P. a. Monica, "LTE unlicensed and Wi-Fi: moving beyond coexistence," Senza Fili, London, 2015.[16] B. a. Jay, "The LTE-U Vs. WiFi Debate," Network computing, 05 Dec 2016. [Online]. Available:https://www.networkcomputing.com/wireless-infrastructure/lte-u-vs-wifi-debate/1619382711. [Accessed 01 Nov 2018].[17] A. V. D. Cavalcante, "Performance Evaluation of LTE and Wi-Fi Coexistence in Unlicensed Bands," IEEE, vol. 1, no. 2, pp. 1-6, 2013. [18] LTE-Forum, "Coexistence Study for LTE-U SDL V1.0 (2015 -02)," LTE-Forum, Stockholm, 2015.[19] S. K. ,. Jian, "Coexistence of Wi-Fi and LAA-LTE: Experimental evaluation, analysis and insights," IEEE, vol. 1, no. 1, pp. 1-7, 2015. [20] B. A.-F. Padden, "Overview of EU LBT and its Effectiveness for Coexistence of LAA LTE and Wi-Fi," 04 11 2014. [Online]. Available: https://vdocuments.site/download/submission-doc-ieee-80219-140082r0-november-2014-alireza-babaei-cablelabsslide. [Accessed 13 08 2018].[21] ns3, "Simulator," ns3, [Online]. Available: https://www.nsnam.org/.[22] 3GPP, "Status report for WI: Licensed-Assisted Access to Unlicensed Spectrum," 3GPP, Spain , 2016.[23] 3GPP, "3GPP TR 36.889, Study on Licensed-Assisted Access to Unlicensed Spectrum," 3GPP, 2015.