  This paper analyzes the efficacy of decoupled wireless access in a two-tier
heterogeneous network. The decoupled wireless access and its performance
benefits have been studied in different scenarios recently. In this paper, an
in-depth analysis on its efficacy from spectral efficiency perspective is
provided. To achieve this task, (i) new closed form expressions for probability
of association of user equipment with different tiers employing different
frequency bands (i.e., microwave and millimeter wave) with different pathloss
exponents are derived using univariate Fox's H-functions; (ii) Distributions of
the distance to the serving base stations are also derived; (iii) Exact
expressions of spectral efficiency for different association cases are further
obtained using bivariate Fox's H-functions. Furthermore, rigorous simulation
results are provided which validate the aforementioned analytical results. In
addition to that, a detailed discussion on the decoupling gain of decoupled
wireless access and its efficacy is also provided. Lastly, despite the
improvement provided by the decoupled wireless access, which is evident from
the results presented in this paper, few questions are raised on its pragmatic
value.
