Finally, Section \[sec:conclusion\] concludes the paper.

System Model {#sec:model}
============

We consider a point-to-point wireless link in which there is one source and one destination. The system model is depicted in Figure \[fig:0\]. It is assumed that the source generates data sequences which are divided into frames of duration $T$. These data frames are initially stored in the buffer before they are transmitted over the wireless channel. The discrete-time channel input-output relation in the $i^{\text{th}}$ symbol duration is given by $$\begin{gathered}
 \label{eq:model}
y[i] = h[i] x[i] + n[i] \quad i = 1,2,\ldots.\end{gathered}$$ where $x[i]$ and $y[i]$ denote the complex-valued channel input and output, respectively. We assume that the bandwidth available in the system is $B$ and the channel input is subject to the following average energy constraint: ${\mathbb{E}}\{|x[i]|^2\}\le {\bar{P}}/ B$ for all $i$. Since the bandwidth is $B$, symbol rate is assumed to be $B$ complex symbols per second, indicating that the average power of the system is constrained by ${\bar{P}}$. Above in (\[eq:model\]), $n[i]$ is a zero-mean, circularly symmetric, complex Gaussian random variable with variance ${\mathbb{E}}\{|n[i]|^2\} = N_0$. The additive Gaussian noise samples $\{n[i]\}$ are assumed to form an independent and identically distributed (i.i.d.) sequence. Finally, $h[i]$ denotes the 