diff --git a/latex/thesis/chapters/decoding_techniques.tex b/latex/thesis/chapters/decoding_techniques.tex index 8d4d60d..429af0e 100644 --- a/latex/thesis/chapters/decoding_techniques.tex +++ b/latex/thesis/chapters/decoding_techniques.tex @@ -142,6 +142,7 @@ which minimizes the objective function $f$ (as shown in figure \ref{fig:dec:spac \label{sec:dec:LP Decoding using ADMM} \Ac{LP} decoding is a subject area introduced by Feldman et al. +\todo{Space before citation?} \cite{feldman_paper}. They reframed the decoding problem as an \textit{integer linear program} and subsequently presented a relaxation into a \textit{linear program}, lifting the integer requirement. @@ -152,27 +153,22 @@ work is the \ac{ADMM}. Feldman at al. begin by looking at the \ac{ML} decoding problem% \footnote{They assume that all codewords are equally likely to be transmitted, -making the \ac{ML} and \ac{MAP} decoding problems essentially equivalent}% -\todo{Dot after footnote?}% +making the \ac{ML} and \ac{MAP} decoding problems essentially equivalent.}% % \begin{align*} - \hat{\boldsymbol{x}} = \argmax_{\boldsymbol{x} \in - \left\{ \left( -1 \right)^{\boldsymbol{c}} - \text{ : } \boldsymbol{c} \in \mathcal{C} \right\} } - f_{\boldsymbol{Y} \mid \boldsymbol{X}} \left( \boldsymbol{y} \mid \boldsymbol{x} \right) + \hat{\boldsymbol{c}} = \argmax_{\boldsymbol{c} \in \mathcal{C}} + f_{\boldsymbol{Y} \mid \boldsymbol{C}} \left( \boldsymbol{y} \mid \boldsymbol{c} \right) .\end{align*} % -\todo{Define $\mathcal{X}$ as $\left\{ \left( -1 \right) - ^{\boldsymbol{c}} : \boldsymbol{c}\in \mathcal{C} \right\} $?}% They suggest that maximizing the likelihood -$f_{\boldsymbol{Y} \mid \boldsymbol{X}}\left( \boldsymbol{y} \mid \boldsymbol{x} \right)$ +$f_{\boldsymbol{Y} \mid \boldsymbol{C}}\left( \boldsymbol{y} \mid \boldsymbol{c} \right)$ is equivalent to minimizing the negative log-likelihood. -\ldots +\ldots (Explaing arriving at cost function from ML decoding problem) Based on this, they propose their cost function% \footnote{In this context, \textit{cost function} and \textit{objective function} -mean the same thing} +mean the same thing.} for the \ac{LP} decoding problem:% % \begin{align*} @@ -184,8 +180,29 @@ for the \ac{LP} decoding problem:% \left( Y_i = y_i | C_i = 1 \right) } \right) \\ .\end{align*} % +% +The exact integer linear program \todo{ILP acronym?} formulation of \ac{ML} +decoding is the following:% +% +\begin{align*} + \text{minimize }\hspace{2mm} &\sum_{i=1}^{n} \gamma_i c_i \\ + \text{subject to }\hspace{2mm} &\boldsymbol{c} \in \mathcal{C} +.\end{align*}% +% -The +\ldots (LP Relaxation) + +%They go on to define the constraints under which this minimization is to be +%accomplished. +%They define the concept of the \textit{codeword polytope} as a linear +%combination of all possible codewords, forming their convex hull:% +%% +%\begin{align*} +% \text{poly}\left( \mathcal{C} \right) = \left\{ +% \sum_{c \in \mathcal{C}} \lambda_{\boldsymbol{c}} \boldsymbol{c} +% \text{ : } \lambda_{\boldsymbol{c}} \ge 0, +% \sum_{\boldsymbol{c} \in \mathcal{C}} \lambda_{\boldsymbol{c}} = 1 \right\} +%.\end{align*} \begin{itemize} \item Equivalent \ac{ML} optimization problem diff --git a/latex/thesis/thesis.tex b/latex/thesis/thesis.tex index 95869f0..1021316 100644 --- a/latex/thesis/thesis.tex +++ b/latex/thesis/thesis.tex @@ -179,7 +179,29 @@ % 7. Conclusion % - Summary of results % - Future work - + + + % Proposed new structure: + % + % 1. Introduction + % + % 2. Theoretical Background + % \ldots + % + % 3. Proximal Decoding + % 3.1 Theory + % 3.2 Implementation details + % 3.3 Results + % 3.x Improved implementation + % + % 4. LP Decoding using ADMM + % 4.1 Theory + % 4.2 Implementation details + % 4.3 Results and comparison with proximal + % + % 5. Discussion + % + % 6. Conclusion \tableofcontents