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ifcs2018_journal.tex
... | ... | @@ -111,7 +111,7 @@ |
111 | 111 | will result in some precision loss. |
112 | 112 | |
113 | 113 | \begin{figure}[h!tb] |
114 | -\includegraphics[width=\linewidth]{images/demo_filtre} | |
114 | +\includegraphics[width=\linewidth]{images/zero_values} | |
115 | 115 | \caption{Impact of the quantization resolution of the coefficients: the quantization is |
116 | 116 | set to 6~bits -- with the horizontal black lines indicating $\pm$1 least significant bit -- setting |
117 | 117 | the 30~first and 30~last coefficients out of the initial 128~band-pass |
118 | 118 | |
... | ... | @@ -251,14 +251,14 @@ |
251 | 251 | |
252 | 252 | \begin{figure} |
253 | 253 | \centering |
254 | -\includegraphics[width=\linewidth]{images/mean_criterion} | |
254 | +\includegraphics[width=\linewidth]{images/colored_mean_criterion} | |
255 | 255 | \caption{Mean criterion comparison between monolithic filter and cascade filters} |
256 | 256 | \label{fig:mean_criterion} |
257 | 257 | \end{figure} |
258 | 258 | |
259 | 259 | \begin{figure} |
260 | 260 | \centering |
261 | -\includegraphics[width=\linewidth]{images/custom_criterion} | |
261 | +\includegraphics[width=\linewidth]{images/colored_custom_criterion} | |
262 | 262 | \caption{Custom criterion comparison between monolithic filter and cascade filters} |
263 | 263 | \label{fig:custom_criterion} |
264 | 264 | \end{figure} |
265 | 265 | |
... | ... | @@ -278,11 +278,16 @@ |
278 | 278 | |
279 | 279 | \begin{figure} |
280 | 280 | \centering |
281 | -\includegraphics[width=\linewidth]{images/sum_rejection} | |
281 | +\includegraphics[width=\linewidth]{images/cascaded_criterion} | |
282 | 282 | \caption{Rejection of two cascaded filters} |
283 | 283 | \label{fig:sum_rejection} |
284 | 284 | \end{figure} |
285 | 285 | |
286 | +The first problem we address is to maximize the rejection under bounded silicon area | |
287 | +and feasibility constraints. Variable $a_i$ is the area taken by filter~$i$ | |
288 | +(in arbitrary unit). Variable $r_i$ is the rejection of filter~$i$ (in dB). | |
289 | +Constant $\mathcal{A}$ is the total available area. We model our problem as follows: | |
290 | + | |
286 | 291 | Finally we can describe our abstract model with following expressions : |
287 | 292 | \begin{align} |
288 | 293 | \text{Maximize } & \sum_{i=1}^n r_i \notag \\ |
... | ... | @@ -295,10 +300,6 @@ |
295 | 300 | \pi_1^- &= \Pi^I \label{eq:init} |
296 | 301 | \end{align} |
297 | 302 | |
298 | -{\color{red} Je sais que l'idée est de ne pas parler du programme linéaire mais | |
299 | -ça me semble quand même indispensable. Au pire, j'essaierai de revoir ça si on | |
300 | -est vraiment en manque de place.} | |
301 | - | |
302 | 303 | Equation~\ref{eq:area} states that the total area taken by the filters must be |
303 | 304 | less than the available area. Equation~\ref{eq:areadef} gives the definition of |
304 | 305 | the area for a filter. More precisely, it is the area of the FIR as the Shifter |
... | ... | @@ -324,9 +325,9 @@ |
324 | 325 | |
325 | 326 | This model is non-linear and even non-quadratic, as $F$ does not have a known |
326 | 327 | linear or quadratic expression. We introduce $p$ FIR configurations |
327 | - $(C_{ij}, \pi_{ij}^C), 1 \leq j \leq p$ that are constants. We define binary | |
328 | - variable $\delta_{ij}$ that has value 1 if stage~$i$ is in configuration~$j$ | |
329 | - and 0 otherwise. The new equations are as follows: | |
328 | +$(C_{ij}, \pi_{ij}^C), 1 \leq j \leq p$ that are constants. We define binary | |
329 | +variable $\delta_{ij}$ that has value 1 if stage~$i$ is in configuration~$j$ | |
330 | +and 0 otherwise. The new equations are as follows: | |
330 | 331 | |
331 | 332 | \begin{align} |
332 | 333 | a_i & = \sum_{j=1}^p \delta_{ij} \times C_{ij} \times (\pi_{ij}^C + \pi_i^-), & \forall i \in [1, n] \label{eq:areadef2} \\ |
... | ... | @@ -339,7 +340,12 @@ |
339 | 340 | respectively equations \ref{eq:areadef}, \ref{eq:rejectiondef} and \ref{eq:bits}. |
340 | 341 | Equation~\ref{eq:config} states that for each stage, a single configuration is chosen at most. |
341 | 342 | |
342 | -The next section shows the results for this quadratic program but the section~\ref{sec:fixed_rej} | |
343 | +This modified model is quadratic, and it can be linearised if necessary. The Gurobi | |
344 | +(\url{www.gurobi.com}) optimization software is used to solve this quadratic | |
345 | +model, and since Gurobi is able to linearize, the model is left as is. This model | |
346 | +has $O(np)$ variables and $O(n)$ constraints. | |
347 | + | |
348 | +The section~\ref{sec:fixed_area} shows the results for the first version of quadratic program but the section~\ref{sec:fixed_rej} | |
343 | 349 | presents the results for the complementary problem. In this case we want |
344 | 350 | minimize the occupied area for a targeted rejection level. Hence we have replace |
345 | 351 | the objective function with: |
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