Stand-alone LTE in unlicensed spectrum: Radio Challenges, Solutions, and Performance of MulteFire

The deployment of standalone LTE radio technology in unlicensed spectrum can enable new business cases by leveraging the assets of LTE to industry players not having access to licensed spectrum. With this objective in mind the MulteFire Alliance has recently finalized first release of the MulteFire standard specifications, which in fact make the deployment of standalone LTE radio technology possible in the 5GHz unlicensed spectrum. MulteFire combines the simplicity of deployment of WiFi with the spectral efficiency and carrier-grade quality of LTE. Though originally thought for enhanced mobile broadband experience, deployment of standalone LTE in unlicensed spectrum is also suited for IoT applications as it inherently supports many connected devices and it can offer more reliable communication compared to other competing technologies working in the unlicensed spectrum. This article provides an overview of the research challenges and solutions of deploying LTE radio technology in unlicensed spectrum. We summarize the main regulatory requirements in the 5GHz unlicensed spectrum, and describe the needed modifications to the LTE specifications; We also demonstrate by means of detailed system level simulations how MulteFire can improve the system capacity and coverage as compared to WiFi in specific propagation environments and small cell deployments.