  Driven by growing spectrum shortage, Long-term Evolution in unlicensed
spectrum (LTE-U) has recently been proposed as a new paradigm to deliver better
performance and experience for mobile users by extending the LTE protocol to
unlicensed spectrum. In the paper, we first present a comprehensive overview of
the LTE-U technology, and discuss the practical challenges it faces. We
summarize the existing LTE-U operation modes and analyze several means for
LTE-U coexistence with Wi-Fi medium access control protocols. We further
propose a novel hyper access-point (HAP) that integrates the functionalities of
LTE small cell base station and commercial Wi-Fi AP for deployment by cellular
network operators. Our proposed LTE-U access embedding within the Wi-Fi
protocol is non-disruptive to unlicensed Wi-Fi nodes and demonstrates
performance benefits as a seamless and novel LTE and Wi-Fi coexistence
technology in unlicensed band. We provide results to demonstrate the
performances advantage of this novel LTE-U proposal.
