A Network Performance Study of LTE in Unlicensed Spectrum

Abstract

The deployment of LTE in unlicensed spectrum has recently been proposed to improve cellular data capacity. Under the title of License Assisted Access (LAA), 3GPP is developing a global standard to enable operators of licensed spectrum to expand into unlicensed spectrum. For regions with less restrictive regulations, the LTE-U Forum has developed a proprietary implementation based on LTE Release 12. Both implementations use carrier aggregation to bond licensed and unlicensed spectrum. This paper investigates the performance of unlicensed LTE using a simulated case study based on a real urban network deployment. Unlicensed LTE is deployed outdoors and is co-located with licensed band LTE picocells. The performance of this network is compared with the identical network using Wi-Fi in the unlicensed band. Results show that unlicensed LTE outperforms Wi-Fi, but the degree depends on the interaction between Wi-Fi and the licensed carrier. In addition, the coexistence of unlicensed LTE using a generic, static muting approach (LTE-U) and Wi-Fi is studied for the case of a single operator. The coexistence results, addressing only the scenario of a single operator with a mixed outdoor deployment in a defined geographic area, show that LTE-U can be configured to yield network performance gains while being fair to the Wi-Fi network.