diff --git a/lib/ftrsd/ftrsd_paper/ftrsd.lyx b/lib/ftrsd/ftrsd_paper/ftrsd.lyx index 9f6a7a8cf..b11d44e1f 100644 --- a/lib/ftrsd/ftrsd_paper/ftrsd.lyx +++ b/lib/ftrsd/ftrsd_paper/ftrsd.lyx @@ -849,7 +849,7 @@ The FT algorithm uses quality indices made available by a noncoherent 64-FSK \end_inset of the symbol's fractional power -\begin_inset Formula $p_{1,\, j}$ +\begin_inset Formula $p_{1,\,j}$ \end_inset in a sorted list of @@ -919,7 +919,7 @@ t educated guesses to select symbols for erasure. , the soft distance between the received word and the codeword: \begin_inset Formula \begin{equation} -d_{s}=\sum_{j=1}^{n}\alpha_{j}\,(1+p_{1,\, j}).\label{eq:soft_distance} +d_{s}=\sum_{j=1}^{n}\alpha_{j}\,(1+p_{1,\,j}).\label{eq:soft_distance} \end{equation} \end_inset @@ -937,7 +937,7 @@ Here \end_inset if the received symbol and codeword symbol are different, and -\begin_inset Formula $p_{1,\, j}$ +\begin_inset Formula $p_{1,\,j}$ \end_inset is the fractional power associated with received symbol @@ -981,7 +981,7 @@ In practice we find that \begin_layout Standard \begin_inset Formula \begin{equation} -u=\frac{1}{n}\sum_{j=1}^{n}S(c_{j},\, j).\label{eq:u-metric} +u=\frac{1}{n}\sum_{j=1}^{n}S(c_{j},\,j).\label{eq:u-metric} \end{equation} \end_inset @@ -1010,7 +1010,7 @@ Here the bins containing noise only. Thus, if the spectral array -\begin_inset Formula $S(i,\, j)$ +\begin_inset Formula $S(i,\,j)$ \end_inset has been normalized so that the average value of the noise-only bins is @@ -1051,17 +1051,39 @@ where \end_inset -In contrast, worst-case incorrect codewords will yield + +\end_layout + +\begin_layout Standard +In contrast, the expected value and standard deviation of the \begin_inset Formula $u$ \end_inset --metrics with expectation value and standard deviation given by +-metric for a randomly selected incorrect codeword (selected from a population + of all +\begin_inset Quotes eld +\end_inset + +worst case +\begin_inset Quotes erd +\end_inset + + codewords, +\emph on +i.e. +\emph default +, those with +\begin_inset Formula $k-1$ +\end_inset + + symbols identical to corresponding ones in the correct word) are given + by \end_layout \begin_layout Standard \begin_inset Formula \begin{equation} -\bar{u}_{2}=1+\left(\frac{k-1}{n}\right)y,\label{eq:u2-exp} +\bar{u}_{i}=1+\left(\frac{k-1}{n}\right)y,\label{eq:u2-exp} \end{equation} \end_inset @@ -1072,39 +1094,72 @@ In contrast, worst-case incorrect codewords will yield \begin_layout Standard \begin_inset Formula \begin{equation} -\sigma_{2}=\frac{1}{n}\left[n+2y(k-1)\right]^{1/2}.\label{eq:sigma2} +\sigma_{i}=\frac{1}{n}\left[n+2y(k-1)\right]^{1/2}.\label{eq:sigma2} \end{equation} \end_inset +If +\begin_inset Formula $u$ +\end_inset -\end_layout - -\begin_layout Standard -If tests on a number of tested candidate codewords yield largest and second-larg -est metrics + is evaluated for a large number of candidate codewords, one of which is + correct, we should expect the largest value \begin_inset Formula $u_{1}$ +\end_inset + + to be drawn from a population with statistics described by +\begin_inset Formula $\bar{u}_{1}$ \end_inset and -\begin_inset Formula $u_{2},$ +\begin_inset Formula $\sigma_{1}.$ \end_inset - respectively, we expect the ratio -\begin_inset Formula $r=u_{2}/u_{1}$ -\end_inset - - to be significantly smaller in cases where the candidate associated with - + If no tested codeword is correct, \begin_inset Formula $u_{1}$ \end_inset - is in fact the correct codeword. - On the other hand, if none of the tested candidates is correct, -\begin_inset Formula $r$ + is likely to come from the +\begin_inset Formula $(\bar{u}_{i},\,\sigma_{i})$ +\end_inset + + population and to be several standard deviations above the mean. + In either case the second-largest value, +\begin_inset Formula $u_{2},$ +\end_inset + + will likely come from the +\begin_inset Formula $(\bar{u}_{i},\,\sigma_{i})$ +\end_inset + + population, again several standard deviations above the mean. + +\end_layout + +\begin_layout Standard +If no tested codeword is correct or the signal-to-noise ratio +\begin_inset Formula $y$ +\end_inset + + is too small for decoding to be possible, the ratio +\begin_inset Formula $r=u_{2}/u_{1}$ \end_inset will likely be close to 1. + On the other hand, correctly identified codewords will produce +\begin_inset Formula $u_{1}$ +\end_inset + + significantly larger than +\begin_inset Formula $u_{2}$ +\end_inset + + and thus smaller values of +\begin_inset Formula $r$ +\end_inset + +. We therefore apply a ratio threshold test, say \begin_inset Formula $r