  License Assisted Access (LAA) LTE (LTE-LAA) is a new type of LTE that
aggregates the licensed LTE bands with the unlicensed bands via carrier
aggregation. To operate in unlicensed bands, LTE-LAA adopts the
listen-before-talk policy and designs its channel access mechanism similar to
WLAN's DCF. In this paper, we consider an LAA network consisting of an LTE-LAA
eNB coexisting with a Wi-Fi STA, and capture the {\em asymmetric hidden
terminal problem} where the eNB recognizes the STA while the opposite is not
true, which is caused by the asymmetric CCA thresholds between them. We model
the network as a joint Markov chain (MC) consisting of two individual MCs, and
derive its steady-state probabilities, throughput, and channel access delay
along with other key metrics like transmit, busy, collision, and doubling
probabilities. Through extensive evaluation, we confirm that the proposed model
well predicts the dynamics of the LAA network, and identify important design
guidelines for fair coexistence between LTE-LAA and WLAN as follows. First,
LTE-LAA should design its contention window (CW) doubling policy by considering
Wi-Fi's packet duration and subframe-dependent collision probabilities. Second,
there exists a tradeoff between throughput and channel access delay, according
to which the CW doubling policy should be adapted.
