Abstract

The technological growth combined with the exponential increase of wireless traffic are pushing the wireless community to investigate solutions to maximally exploit the available spectrum. Among the proposed solutions, the operation of Long Term Evolution (LTE) in the unlicensed spectrum (LTE-U) has attracted significant attention. Recently, the 3rd Generation Partnership Project announced specifications that allow LTE to transmit in the unlicensed spectrum using a Listen Before Talk (LBT) procedure, respecting this way the regulator requirements worldwide. However, the proposed standards may cause coexistence issues between LTE and legacy Wi-Fi networks. In this article, it is discussed that a fair coexistence mechanism is needed to guarantee equal channel access opportunities for the co-located networks in a technology-agnostic way, taking into account potential traffic requirements. In order to enable harmonious coexistence and fair spectrum sharing among LTE-U and Wi-Fi, an adaptive LTE-U LBT scheme is presented. This scheme uses a variable LTE transmission opportunity (TXOP) followed by a variable muting period. This way, co-located Wi-Fi networks can exploit the muting period to gain access to the wireless medium. The scheme is studied and evaluated in different compelling scenarios using a simulation platform. The results show that by configuring the LTE-U with the appropriate TXOP and muting period values, the proposed scheme can significantly improve the coexistence among LTE-U and Wi-Fi in a fair manner. Finally, a preliminary algorithm is proposed on how the optimal configuration parameters can be selected towards harmonious and fair coexistence.

Highlights

  • Over the last years, the technological growth has led to a tremendous increase of wireless devices such as smartphones, tablets, laptops and wearable technologies

  • Towards a fair coexistence in line with the second approach that discussed above, the parameters of muting LTE-U (mLTE-U) are selected in such a way that each participating network can achieve an equal ratio of throughput, compared to the maximum throughput that it can be achieved during the standalone operation

  • This article proposes a new coexistence scheme that can enable a fair coexistence of Long Term Evolution (LTE)-U and Wi-Fi

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Summary

Introduction

The technological growth has led to a tremendous increase of wireless devices such as smartphones, tablets, laptops and wearable technologies. We discuss a way that fairness can be achieved between LTE-U and Wi-Fi. We define a new adaptive LTE-U transmission scheme according to which LTE can transmit in unlicensed spectrum using a variable TXOP time. We define a new adaptive LTE-U transmission scheme according to which LTE can transmit in unlicensed spectrum using a variable TXOP time This TXOP period is followed by a variable muting period in order to give channel access opportunities to other potentially co-located networks, such as Wi-Fi. Before a TXOP, LTE must perform a CCA procedure in order to determine the availability of the channel. Before a TXOP, LTE must perform a CCA procedure in order to determine the availability of the channel This scheme can be used for LTE transmissions in the unlicensed spectrum next to the primary cell that an operator uses in the licensed spectrum similar to LTE LAA.

LTE and Wi-Fi in a nutshell
Related work
Problem definition and proposal description
Fairness in unlicensed spectrum
Simulation environment
Simulation scenarios
Standalone scenario evaluation
Reference scenario evaluation
Dense mLTE-U deployment scenario evaluation
Dense Wi-Fi deployment scenario evaluation
Dense mLTE-U and Wi-Fi deployment scenario evaluation
Automatic fair parameter selection
Findings
10 Conclusions and future work
Full Text
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