  Exploiting the unlicensed spectrum is considered by 3GPP as one promising
solution to meet the ever-increasing traffic growth. As a result, one major
enhancement for LTE in Release 13 has been to enable its operation in the
unlicensed spectrum via Licensed-Assisted Access (LAA). In this article, we
provide an overview of the Release 13 LAA technology including motivation, use
cases, LTE enhancements for enabling the unlicensed band operation, and the
coexistence evaluation results contributed by 3GPP participants.
