Appendix A: Proof of Theorem 1
From (13), \(A\) can be formulated by
$$ \begin{gathered} A = \Pr \left( {\left| {h_{1n*} } \right|^{2} > \frac{\xi }{{P_{BS}^{\max } }},P_{BS}^{\max } < \frac{H}{{\left| {h_{p1*} } \right|^{2} }}} \right) + \Pr \left( {\left| {h_{1n*} } \right|^{2} > \frac{\xi }{{\frac{H}{{\left| {h_{p1*} } \right|^{2} }}}},P_{BS}^{\max } > \frac{H}{{\left| {h_{p1*} } \right|^{2} }}} \right) \hfill \\ = \underbrace {{\Pr \left( {\left| {h_{1n*} } \right|^{2} > \frac{\xi }{{P_{BS}^{\max } }},P_{BS}^{\max } < \frac{H}{{\left| {h_{p1*} } \right|^{2} }}} \right)}}_{{A_{1} }} + \underbrace {{\Pr \left( {\left| {h_{1n*} } \right|^{2} > \frac{\xi }{{\frac{H}{{\left| {h_{p1*} } \right|^{2} }}}},P_{BS}^{\max } > \frac{H}{{\left| {h_{p1*} } \right|^{2} }}} \right)}}_{{A_{2} }}. \hfill \\ \end{gathered} $$
(A.1)
Next, \(A_{1}\) it can be first calculated as
$$ \begin{gathered} A_{1} = \Pr \left( {\left| {h_{1n*} } \right|^{2} > \frac{\xi }{{P_{BS}^{\max } }},\left| {h_{p1} } \right|^{2} < \frac{H}{{P_{BS}^{\max } }}} \right) = \Pr \left( {\left| {h_{1n*} } \right|^{2} > \frac{\xi }{{P_{BS}^{\max } }}} \right)\left[ {1 - \Pr \left( {\left| {h_{p1} } \right|^{2} \ge \frac{H}{{P_{BS}^{\max } }}} \right)} \right] \hfill \\ \begin{array}{*{20}c} {} & {} \\ \end{array} = \sum\limits_{n = 1}^{N} {\left( \begin{gathered} N \hfill \\ n \hfill \\ \end{gathered} \right)\left( { - 1} \right)^{n - 1} } \exp \left( { - \frac{n\xi }{{P_{BS}^{\max } \lambda_{1n} }}} \right) \times \left[ {1 - \sum\limits_{n = 1}^{N} {\left( \begin{gathered} N \hfill \\ n \hfill \\ \end{gathered} \right)\left( { - 1} \right)^{n - 1} } \exp \left( { - \frac{nH}{{P_{BS}^{\max } \lambda_{p1} }}} \right)} \right]. \hfill \\ \end{gathered} $$
(A.2)
In a similar way, \(A_{2}\) it can be first calculated as
$$ \begin{gathered} A_{2} = \Pr \left( {\left| {h_{1n*} } \right|^{2} > \frac{{\left| {h_{p1*} } \right|^{2} \xi }}{H},\left| {h_{p1*} } \right|^{2} > \frac{H}{{P_{BS}^{\max } }}} \right) = \int_{{\frac{H}{{P_{BS}^{\max } }}}}^{\infty } {\left( {1 - F_{{\left| {h_{1n*} } \right|^{2} }} \left( {\frac{\xi x}{H}} \right)} \right)f_{{\left| {h_{p1*} } \right|^{2} }} \left( x \right)dx} \hfill \\ = \sum\limits_{n = 1}^{N} {\sum\limits_{m = 1}^{N} {\left( \begin{gathered} N \hfill \\ n \hfill \\ \end{gathered} \right)\left( \begin{gathered} N \hfill \\ m \hfill \\ \end{gathered} \right)\left( { - 1} \right)^{n + m - 2} } \frac{m}{{\lambda_{p1} }}} \int_{{\frac{H}{{P_{BS}^{\max } }}}}^{\infty } {\exp \left( { - \left( {\frac{n\xi }{{H\lambda_{1n} }} + \frac{m}{{\lambda_{p1} }}} \right)x} \right)dx} \hfill \\ = \sum\limits_{n = 1}^{N} {\sum\limits_{m = 1}^{N} {\left( \begin{gathered} N \hfill \\ n \hfill \\ \end{gathered} \right)\left( \begin{gathered} N \hfill \\ m \hfill \\ \end{gathered} \right)\left( { - 1} \right)^{n + m - 2} } } \frac{{mH\lambda_{1n} }}{{n\xi \lambda_{p1} + mH\lambda_{1n} }} \times \exp \left( { - \left( {\frac{n\xi }{{H\lambda_{1n} }} + \frac{m}{{\lambda_{p1} }}} \right)\frac{H}{{P_{BS}^{\max } }}} \right). \hfill \\ \end{gathered} $$
(A.3)
From (A.2) and (A.3), \(A\) can write such as
$$ \begin{gathered} A = \sum\limits_{n = 1}^{N} {\left( \begin{gathered} N \hfill \\ n \hfill \\ \end{gathered} \right)\left( { - 1} \right)^{n - 1} } \exp \left( { - \frac{n\xi }{{P_{BS}^{\max } \lambda_{1n} }}} \right) \times \left[ {1 - \sum\limits_{n = 1}^{N} {\left( \begin{gathered} N \hfill \\ n \hfill \\ \end{gathered} \right)\left( { - 1} \right)^{n - 1} } \exp \left( { - \frac{nH}{{P_{BS}^{\max } \lambda_{p1} }}} \right)} \right] \hfill \\ + \sum\limits_{n = 1}^{N} {\sum\limits_{m = 1}^{N} {\left( \begin{gathered} N \hfill \\ n \hfill \\ \end{gathered} \right)\left( \begin{gathered} N \hfill \\ m \hfill \\ \end{gathered} \right)\left( { - 1} \right)^{n + m - 2} } } \frac{{mH\lambda_{1n} }}{{n\xi \lambda_{p1} + mH\lambda_{1n} }} \times \exp \left( { - \left( {\frac{n\xi }{{H\lambda_{1n} }} + \frac{m}{{\lambda_{p1} }}} \right)\frac{H}{{P_{BS}^{\max } }}} \right). \hfill \\ \end{gathered} $$
(A.4)
We plug (A.4) into (13), it can be achieved \(OP_{1}^{{}}\) as the proposition.
This is the end of the proof.
Appendix B: Proof of Theorem 2
From (15), \(B_{1}\) can be formulated by
$$ \begin{aligned} B_{1} &=\, \Pr \left( {\gamma_{{BS - D_{2} *}}^{{\left( {x_{2} } \right)}} \ge \varepsilon_{2} } \right) = \Pr \left( {\left| {h_{2n*} } \right|^{2} \ge \frac{{\varepsilon_{2} \omega_{0} }}{{P_{BS}^{\max } \left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)}},P_{BS}^{\max } < \frac{H}{{\left| {h_{p1*} } \right|^{2} }}} \right) \\& - \, \Pr \left( {\left| {h_{2n*} } \right|^{2} \ge \frac{{\varepsilon_{2} \omega_{0} }}{{\frac{H}{{\left| {h_{p1*} } \right|^{2} }}\left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)}},P_{BS}^{\max } > \frac{H}{{\left| {h_{p1*} } \right|^{2} }}} \right) \hfill \\& = \, \underbrace {{\Pr \left( {\left| {h_{2n*} } \right|^{2} \ge \frac{{\varepsilon_{2} \omega_{0} }}{{P_{BS}^{\max } \left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)}},P_{BS}^{\max } < \frac{H}{{\left| {h_{p1*} } \right|^{2} }}} \right)}}_{{B_{1a} }}\\& - \, \underbrace {{\Pr \left( {\left| {h_{2n*} } \right|^{2} \ge \frac{{\varepsilon_{2} \omega_{0} \left| {h_{p1*} } \right|^{2} }}{{H\left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)}},P_{BS}^{\max } > \frac{H}{{\left| {h_{p1*} } \right|^{2} }}} \right)}}_{{B_{1b} }}. \end{aligned} $$
(B.1)
Next, \(B_{1a}\) it can be first calculated as
$$ \begin{gathered} B_{1a} = \Pr \left( {\left| {h_{2n*} } \right|^{2} \ge \frac{{\varepsilon_{2} \omega_{0} }}{{P_{BS}^{\max } \left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)}}} \right) \times \left[ {1 - \Pr \left( {\left| {h_{p1*} } \right|^{2} \ge \frac{H}{{P_{BS}^{\max } }}} \right)} \right] \hfill \\ = \sum\limits_{n = 1}^{N} {\left( \begin{gathered} N \hfill \\ n \hfill \\ \end{gathered} \right)\left( { - 1} \right)^{n - 1} } \exp \left( { - \frac{{n\varepsilon_{2} \omega_{0} }}{{P_{BS}^{\max } \left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)\lambda_{2n} }}} \right) \times \left[ {1 - \sum\limits_{n = 1}^{N} {\left( \begin{gathered} N \hfill \\ n \hfill \\ \end{gathered} \right)\left( { - 1} \right)^{n - 1} } \exp \left( { - \frac{nH}{{P_{BS}^{\max } \lambda_{p1} }}} \right)} \right]. \hfill \\ \end{gathered} $$
(B.2)
From (B.1), \(B_{1b}\) it can be first calculated as
$$ \begin{gathered} B_{1b} = \Pr \left( {\left| {h_{2n*} } \right|^{2} \ge \frac{{\varepsilon_{2} \omega_{0} \left| {h_{p1*} } \right|^{2} }}{{H\left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)}},\left| {h_{p1*} } \right|^{2} > \frac{H}{{P_{BS}^{\max } }}} \right) = \int_{{\frac{H}{{P_{BS}^{\max } }}}}^{\infty } {\left( {1 - F_{{\left| {h_{2n*} } \right|^{2} }} \left( {\frac{{\varepsilon_{2} \omega_{0} x}}{{H\left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)}}} \right)} \right)f_{{\left| {h_{p1*} } \right|^{2} }} \left( x \right)dx} \hfill \\ \begin{array}{*{20}c} {} & {} \\ \end{array} = \sum\limits_{n = 1}^{N} {\sum\limits_{m = 1}^{N} {\left( \begin{gathered} N \hfill \\ n \hfill \\ \end{gathered} \right)\left( \begin{gathered} N \hfill \\ m \hfill \\ \end{gathered} \right)\left( { - 1} \right)^{n + m - 2} } \frac{m}{{\lambda_{p1} }}} \times \int_{{\frac{H}{{P_{BS}^{\max } }}}}^{\infty } {\exp \left( { - \left( {\frac{{n\varepsilon_{2} \omega_{0} }}{{H\left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)\lambda_{2n} }} + \frac{m}{{\lambda_{p1} }}} \right)x} \right)dx} \hfill \\ \begin{array}{*{20}c} {} & {} \\ \end{array} = \sum\limits_{n = 1}^{N} {\sum\limits_{m = 1}^{N} {\left( \begin{gathered} N \hfill \\ n \hfill \\ \end{gathered} \right)\left( \begin{gathered} N \hfill \\ m \hfill \\ \end{gathered} \right)\left( { - 1} \right)^{n + m - 2} } } \frac{{mH\left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)\lambda_{2n} }}{{n\varepsilon_{2} \omega_{0} \lambda_{p1} + mH\left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)\lambda_{2n} }} \times \exp \left( { - \left( {\frac{{n\varepsilon_{2} \omega_{0} }}{{H\left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)\lambda_{2n} }} + \frac{m}{{\lambda_{p1} }}} \right)\frac{H}{{P_{BS}^{\max } }}} \right). \hfill \\ \end{gathered} $$
(B.3)
From (B.2) and (B.3), \(B_{1}\) can written such as
$$ \begin{gathered} B_{1} = \sum\limits_{n = 1}^{N} {\left( \begin{gathered} N \hfill \\ n \hfill \\ \end{gathered} \right)\left( { - 1} \right)^{n - 1} } \exp \left( { - \frac{{n\varepsilon_{2} \omega_{0} }}{{P_{BS}^{\max } \left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)\lambda_{2n} }}} \right) \times \left[ {1 - \sum\limits_{n = 1}^{N} {\left( \begin{gathered} N \hfill \\ n \hfill \\ \end{gathered} \right)\left( { - 1} \right)^{n - 1} } \exp \left( { - \frac{nH}{{P_{BS}^{\max } \lambda_{p1} }}} \right)} \right] \hfill \\ \begin{array}{*{20}c} {} & {} \\ \end{array} + \sum\limits_{n = 1}^{N} {\sum\limits_{m = 1}^{N} {\left( \begin{gathered} N \hfill \\ n \hfill \\ \end{gathered} \right)\left( \begin{gathered} N \hfill \\ m \hfill \\ \end{gathered} \right)\left( { - 1} \right)^{n + m - 2} } } \frac{{mH\left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)\lambda_{2n} }}{{n\varepsilon_{2} \omega_{0} \lambda_{p1} + mH\left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)\lambda_{2n} }} \times \exp \left( { - \left( {\frac{{n\varepsilon_{2} \omega_{0} }}{{H\left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)\lambda_{2n} }} + \frac{m}{{\lambda_{p1} }}} \right)\frac{H}{{P_{BS}^{\max } }}} \right). \hfill \\ \end{gathered} $$
(B.4)
From (15), \(B_{2}\) can be formulated by
$$ B_{2} = \Pr \left( {\min \left( {\gamma_{{D_{1} *}}^{{\left( {x_{2} } \right)}} ,\gamma_{{D_{1} - D_{2} *}}^{{\left( {x_{2} } \right)}} } \right) < \varepsilon_{2} } \right) = 1 - \underbrace {{\Pr \left( {\gamma_{{D_{1} *}}^{{\left( {x_{2} } \right)}} \ge \varepsilon_{2} } \right)}}_{{B_{2a} }}\underbrace {{\Pr \left( {\gamma_{{D_{1} - D_{2} *}}^{{\left( {x_{2} } \right)}} \ge \varepsilon_{2} } \right)}}_{{B_{2b} }}. $$
(B.5)
\(B_{2a}\) can be formulated such as \(B_{1}\), we have
$$ \begin{gathered} B_{2a} = \sum\limits_{n = 1}^{N} {\left( \begin{gathered} N \hfill \\ n \hfill \\ \end{gathered} \right)\left( { - 1} \right)^{n - 1} } \exp \left( { - \frac{{n\varepsilon_{2} \omega_{0} }}{{P_{BS}^{\max } \left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)\lambda_{1n} }}} \right) \times \left[ {1 - \sum\limits_{n = 1}^{N} {\left( \begin{gathered} N \hfill \\ n \hfill \\ \end{gathered} \right)\left( { - 1} \right)^{n - 1} } \exp \left( { - \frac{nH}{{P_{BS}^{\max } \lambda_{p1} }}} \right)} \right] \hfill \\ \begin{array}{*{20}c} {} & {} \\ \end{array} + \sum\limits_{n = 1}^{N} {\sum\limits_{m = 1}^{N} {\left( \begin{gathered} N \hfill \\ n \hfill \\ \end{gathered} \right)\left( \begin{gathered} N \hfill \\ m \hfill \\ \end{gathered} \right)\left( { - 1} \right)^{n + m - 2} } } \frac{{mH\left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)\lambda_{1n} }}{{n\varepsilon_{2} \omega_{0} \lambda_{p1} + mH\left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)\lambda_{1n} }} \times \exp \left( { - \left( {\frac{{n\varepsilon_{2} \omega_{0} }}{{H\left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)\lambda_{1n} }} + \frac{m}{{\lambda_{p1} }}} \right)\frac{H}{{P_{BS}^{\max } }}} \right). \hfill \\ \end{gathered} $$
(B.6)
From (B.5), \(B_{2b}\) it can be first calculated as
$$ \begin{gathered} B_{2b} = \Pr \left( {\gamma_{{D_{1} - D_{2} }}^{{\left( {x_{2} } \right)}} \ge \varepsilon_{2} } \right) = \Pr \left( {\min \left\{ {P_{{D_{1} }}^{EH} ,P_{{D_{1} }}^{\max } ,H/\left| {h_{p2} } \right|^{2} } \right\} \ge \omega_{0} \varepsilon_{2} } \right) \hfill \\ = \Pr \left( {P_{{D_{1} }}^{EH} \ge \frac{{\omega_{0} \varepsilon_{2} }}{{\left| {h_{3} } \right|^{2} }}} \right)\Pr \left( {P_{{D_{1} }}^{\max } \ge \frac{{\omega_{0} \varepsilon_{2} }}{{\left| {h_{3} } \right|^{2} }}} \right)\Pr \left( {\frac{H}{{\left| {h_{p2} } \right|^{2} }} \ge \frac{{\omega_{0} \varepsilon_{2} }}{{\left| {h_{3} } \right|^{2} }}} \right) \hfill \\ = \exp \left( { - \frac{{\omega_{0} \varepsilon_{2} }}{{P_{{D_{1} }}^{\max } \lambda_{3} }}} \right)\underbrace {{\Pr \left( {\left| {h_{3} } \right|^{2} \ge \frac{{\omega_{0} \varepsilon_{2} \left( {1 - \chi } \right)}}{{2\theta P_{B} \chi \left| {h_{b} } \right|^{2} }}} \right)}}_{{B_{2b}^{\left( 1 \right)} }} \times \underbrace {{\Pr \left( {\left| {h_{3} } \right|^{2} \ge \frac{{\omega_{0} \varepsilon_{2} \left| {h_{p2} } \right|^{2} }}{H}} \right)}}_{{B_{2b}^{\left( 2 \right)} }}. \hfill \\ \end{gathered} $$
(B.7)
From (B.7), \(B_{2b}^{\left( 1 \right)}\) it can be first calculated as
$$ \begin{gathered} B_{2b}^{\left( 1 \right)} = \Pr \left( {\left| {h_{3} } \right|^{2} \ge \frac{{\omega_{0} \varepsilon_{2} \left( {1 - \chi } \right)}}{{2\theta P_{B} \chi \left| {h_{b} } \right|^{2} }}} \right) = \int_{0}^{\infty } {\exp \left( { - \frac{{\omega_{0} \varepsilon_{2} \left( {1 - \chi } \right)}}{{2\theta P_{B} \chi \lambda_{3} x}}} \right)\frac{1}{{\lambda_{b} }}\exp \left( { - \frac{x}{{\lambda_{b} }}} \right)dx} \hfill \\ = \sqrt {\frac{{2\omega_{0} \varepsilon_{2} \left( {1 - \chi } \right)}}{{\theta P_{B} \chi \lambda_{3} \lambda_{b} }}} K_{1} \left( {\sqrt {\frac{{2\omega_{0} \varepsilon_{2} \left( {1 - \chi } \right)}}{{\theta P_{B} \chi \lambda_{3} \lambda_{b} }}} } \right). \hfill \\ \end{gathered} $$
(B.8)
It is worth noting that the last equation follows from the fact that.
\(\int_{0}^{\infty } {\exp \left( { - \frac{\delta }{4x} - \varphi x} \right)dx} = \sqrt {\frac{\delta }{\varphi }} K_{1} \left( {\sqrt {\delta \varphi } } \right)\) in [25, Eq. (3.324)].
From (B.7), \(B_{2b}^{\left( 2 \right)}\) it can be first calculated as
$$ B_{2b}^{\left( 2 \right)} = \Pr \left( {\left| {h_{3} } \right|^{2} \ge \frac{{\omega_{0} \varepsilon_{2} \left| {h_{p2} } \right|^{2} }}{H}} \right) = \frac{1}{{\lambda_{p2} }}\int_{0}^{\infty } {\exp \left( { - \left( {\frac{{\omega_{0} \varepsilon_{2} }}{{H\lambda_{3} }} + \frac{1}{{\lambda_{p2} }}} \right)x} \right)dx} = \frac{{H\lambda_{3} }}{{\omega_{0} \varepsilon_{2} \lambda_{p2} + H\lambda_{3} }}. $$
(B.9)
From (B.6), (B.7), (B.8) and (B.9), \(B_{2}\) can written such as
$$ \begin{gathered} B_{2} = 1 - \left\{ {\sum\limits_{n = 1}^{N} {\left( \begin{gathered} N \hfill \\ n \hfill \\ \end{gathered} \right)\left( { - 1} \right)^{n - 1} } \exp \left( { - \frac{{n\varepsilon_{2} \omega_{0} }}{{P_{BS}^{\max } \left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)\lambda_{1n} }}} \right)\left[ {1 - \sum\limits_{n = 1}^{N} {\left( \begin{gathered} N \hfill \\ n \hfill \\ \end{gathered} \right)\left( { - 1} \right)^{n - 1} } \exp \left( { - \frac{nH}{{P_{BS}^{\max } \lambda_{p1} }}} \right)} \right]} \right. \hfill \\ \left. \begin{gathered} \begin{array}{*{20}c} {} & {} \\ \end{array} + \sum\limits_{n = 1}^{N} {\sum\limits_{m = 1}^{N} {\left( \begin{gathered} N \hfill \\ n \hfill \\ \end{gathered} \right)\left( \begin{gathered} N \hfill \\ m \hfill \\ \end{gathered} \right)\left( { - 1} \right)^{n + m - 2} } } \frac{{mH\left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)\lambda_{1n} }}{{n\varepsilon_{2} \omega_{0} \lambda_{p1} + mH\left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)\lambda_{1n} }} \hfill \\ \begin{array}{*{20}c} {} & {} \\ \end{array} \times \exp \left( { - \left( {\frac{{n\varepsilon_{2} \omega_{0} }}{{H\left( {\beta_{2} - \varepsilon_{2} \beta_{1} } \right)\lambda_{1n} }} + \frac{m}{{\lambda_{p1} }}} \right)\frac{H}{{P_{BS}^{\max } }}} \right) \hfill \\ \end{gathered} \right\} \hfill \\ \begin{array}{*{20}c} {} & {} \\ \end{array} \times \frac{{H\lambda_{3} }}{{\omega_{0} \varepsilon_{2} \lambda_{p2} + H\lambda_{3} }}\exp \left( { - \frac{{\omega_{0} \varepsilon_{2} }}{{P_{{D_{1} }}^{\max } \lambda_{3} }}} \right) \times \sqrt {\frac{{2\omega_{0} \varepsilon_{2} \left( {1 - \chi } \right)}}{{\theta P_{B} \chi \lambda_{3} \lambda_{b} }}} K_{1} \left( {\sqrt {\frac{{2\omega_{0} \varepsilon_{2} \left( {1 - \chi } \right)}}{{\theta P_{B} \chi \lambda_{3} \lambda_{b} }}} } \right). \hfill \\ \end{gathered} $$
(B.10)
We plug (B.4), (B.10) into (15), it can be achieved \(OP_{2}\) as the proposition.
This is the end of the proof.