deletions | additions       diff --git a/untitled.tex b/untitled.tex  index 7e85f02..b70f3d0 100644  --- a/untitled.tex  +++ b/untitled.tex 
...
Rate adaptation schemes for other single-user networks (such as MIMO networks and amplify-and-forward relay networks) can be designed in a similar way.  \subsection{Challenges for Rate Adaptation for Multiuser Networks with Limited Feedback}  Take the decode-and-forward relay network (one source ${\sf S}$, $N$ decode-and-forward relays ${\sf R}_1, \ldots, {\sf R}_N$ and one destination $\sf D$) for example. The goal is to find the maximum achieved data rate at $\sf D$ for each channel state without outage. The challenges here include:  \begin{enumerate}  \item   \end{enumerate}  \section{Non-Orthogonal Multiple-Access (NOMA) Systems with Limited Feedback}  In the future 5G communication systems, a promising downlink multiple access scheme is the non-orthogonal multiple access (NOMA) which achieves high spectral efficiencies by combining superposition coding at the transmitter with successive