Resource Management in LTE-U Systems: Past, Present, and Future

Rui Liu,Geoffrey Ye Li,Guanding Yu,Qimei Chen,ZHI DING

doi:10.1109/ojvt.2019.2949020

Abstract

With the tremendous growth in mobile data traffic, wireless cellular networks are facing a rigorous challenge to increase network capacity. Despite that many advanced technologies are used, the shortage of spectrum resource is still the main bottleneck for capacity enhancement. To address the challenge, the cellular networks have been motivated to seek for more fruitful radio spectra. Amongst many others, the unlicensed 5 GHz spectrum is a promising candidate due to its low channel attenuation, large available bandwidth, and easy to utilize. Therefore, the innovative technology of long-term evolution (LTE) using the unlicensed spectrum, known as LTE-Unlicensed (LTE-U), has been widely investigated as a promising means to increase the data rate of cellular networks. The unique characteristics of the unlicensed spectrum bring new challenges to resource management in the LTE-U system. During the last few years, there have been a lot of resource management designs for the newly-born but vigorous LTE-U technologies. This paper provides a comprehensive overview of the state-of-the-art resource management scenarios in LTE-U systems, including single small cell base station (SBS), multiple SBSs, device-to-device (D2D) networks, vehicular networks, and unmanned aerial vehicle (UAV) systems. The future research issues of resource management in LTE-U for 5G are also outlined.

Highlights

W IRELESS communications have witnessed an unprecedented proliferation in both the number of mobile terminals and the traffic demand for various multimedia applications
We focus on the resource management issue in different longterm evolution (LTE)-U scenarios
By analogy to existing studies focusing on ultra-dense mmWave networks, such as [95], it is intuitive to design a basic two-tier hierarchical architecture where the top tier consists of LTE-U small cell base station (SBS) focusing on network control, information measurement, and control signaling transmission, while the second tier consists of mmWave access point (AP) focusing on data transmission

Summary

INTRODUCTION

W IRELESS communications have witnessed an unprecedented proliferation in both the number of mobile terminals and the traffic demand for various multimedia applications. The seamless convergence of such technologies within the same architecture has allowed the traditional licensed spectrum to meet current network performance demands in addition to promoting a high spectral efficiency of the current wireless cellular network. The MulteFire, on the other hand, operates the LTE-based technology solely in unlicensed spectrum and provides a more flexible deployment scenario for LTE-U [26]. In this article, we utilize the concept “LTE-U” to cover all technologies that extend 3GPP LTE systems to the unlicensed spectrum. From the perspective of the user side, leveraging the existing CA technology, cellular users can access both licensed and unlicensed spectra to boost their data rates. To the best of our knowledge, this is the first to provide a comprehensive survey on resource management in different scenarios of LTE-U systems.

FUNDAMENTALS

RESOURCE MANAGEMENT IN MULTIPLE SBSS SCENARIO

FUTURE RESEARCH ISSUES

Findings

CONCLUSION