 (LAA) for Release 13. The study phase was finalized in June 2015 and the actual work item scheduled being finalized by end of 2015. The use of LAA allows benefiting from the additional capacity available from the unlicensed spectrum. This is possible especially in the public hot spot and corporate type of environment to provide additional capacity for the licensed band operation. This chapter introduces first the 5 GHz frequency band under consideration with the key regulatory requirements to be considered and then covers the motivation for using LTE in unlicensed spectrum and the LTE unlicensed operation principles. The unlicensed band-specific coexistence issues are addressed as well as the relative performance in terms of achievable capacity and coverage of LAA for LTE Small Cell Optimization: 3GPP Evolution to Release 13, First Edition. Edited by Harri Holma, Antti Toskala and Jussi Reunanen. © 2016 John Wiley & Sons, Ltd. Published 2016 by John Wiley & Sons, Ltd. LTE Small Cell Optimization 200 mW or less Typically 1 W United States Europe Japan China Figure 10.1 Unlicensed spectrum availability in different regions LTE compared to using Wi-Fi in the 5 GHz band, including the performance when coexisting with Wi-Fi on the same channel. 3GPP standardization plans and expected schedule are also covered before concluding this chapter. Unlicensed Spectrum The frequency band of main interest in 3GPP is the 5 GHz band, which has a lot of unlicensed spectrum available globally, much more than the 2.4 GHz frequency band. Most markets offer large amount of spectrum in the 5 GHz band, for example, in Europe there is 455 MHz of spectrum available in the band as shown in the Figure 10.1. Allocations are also available in countries like Korea and Japan in 5 GHz band. In the United States, there is more than 600 MHz spectrum available on this band and the upper part of the 5 GHz band (US 5.725- 5.850 GHz) differs from other regions as the regulation mainly restricts only items such as maximum transmission power there. How