The END IS NEAR
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@ -104,12 +104,12 @@ Its cardinality is $2^M$, while $M$ defines the number of bits we want to extrac
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It has to be noted, that $bold(cal(o))$ consists of optimal values that we may not be able to exactly approximate using a linear combination based on weights and our given input values.
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In comparison to the 1-bit sign-based quantization, we will not be able to find a linear combination of only two input values that approximates the optimal points we defined earlier.
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Therefore, we will use -- without any loss of generality -- three summands for the linear combination as this give us more flexible control over the result of the linear combination with the helper data.
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Therefore, we will use three or more summands for the linear combination as this give us more flexible control over the result of the linear combination with the helper data.
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Later we will be able to show that a higher number of summands for $z$ can provide better approximations for the ideal values of $z$ at the expense of the number of available input values for the quantizer.
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We will define $z$ from now on as:
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$
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z = x_1 dot h_1 plus x_2 dot h_2 plus x_3 dot h_3.
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z = sum_(i=3)^n x_i dot h_i
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$<eq:z_eq>
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We can now find the optimal linear combination $z_"opt"$ by finding the minimum of all distances to all optimal points defined as $bold(cal(o))$.
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@ -161,4 +161,23 @@ We can now use an iterative algorithm that alternates between optimizing the qua
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kind: "algorithm",
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supplement: [Algorithm],
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include("../pseudocode/bach_1.typ")
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)
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)<alg:bach_1>
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We can see both of these alternating parts in @alg:bach_1_2[Lines] and @alg:bach_1_3[] of @alg:bach_1.
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To optimize the quantizing bounds of $cal(Q)$, we will sort the values of all the resulting linear combinations $bold(z)_"opt"$ in ascending order.
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Using the inverse @ecdf defined in @eq:ecdf_inverse, we can find new quantizer bounds based on $bold(z)_"opt"$ from the first iteration.
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These bounds will then be used to define a new set of optimal points $bold(cal(o))$ used for the next iteration.
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During every iteration of @alg:bach_1, we will store all weights $bold(h)$ used to generate the vector for optimal linear combinations $bold(z)_"opt"$.
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The output of @alg:bach_1 is the vector of optimal weights $bold(h)_"opt"$.
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$bold(h)_"opt"$ can now be used to complete the enrollment phase and quantize the values $bold(z)_"opt"$.
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=== Maximum quantizing bound distance approximation
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Instead of defining the optimal positions for $z$ with fixed values, we can also provide a more loose definition of $bold(cal(o))$.
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Let's consider the following example:
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== Experiments
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== Results & Discussion
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@ -1,3 +1,4 @@
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#import "@preview/glossarium:0.4.1": *
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= Introduction
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These are the introducing words
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@ -39,6 +40,23 @@ This transformation can be performed using the function $xi = tilde(x)$. The key
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Considering a normal distribution, the CDF is defined as
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$ xi(frac(x - mu, sigma)) = frac(1, 2)[1 + \e\rf(frac(x - mu, sigma sqrt(2)))] $
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==== ECDF
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==== #gls("ecdf", display: "Empirical cumulative distribution function (eCDF)")
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The @ecdf is constructed through sorting the empirical measurements of a distribution @dekking2005modern. Although less accurate, this method allows a more simple and less computationally complex way to transform real valued measurements into the Tilde-Domain. We will mainly use the eCDF in @chap:smhd because of the difficulty of finding an analytical description for the CDF of a Gaussian-Mixture.\
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To apply it, we will sort the vector of realizations $bold(z)$ of a random distributed variable $Z$ in ascending order.
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The function for an @ecdf can be defined as
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$
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xi_#gls("ecdf") (x) = frac("number of elements in " bold(z)", that" <= x, n) in [0, 1],
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$<eq:ecdf_def>
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where $n$ defines the number of elements in the vector $bold(z)$.
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If the vector $bold(z)$ were to contain the elements $[1, 3, 4, 5, 7, 9, 10]$ and $x = 5$, @eq:ecdf_def would result to $xi_#gls("ecdf") (5) = frac(4, 7)$.\
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The application of @eq:ecdf_def on $X$ will transform its values into the empirical tilde-domain.
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We can also define an inverse @ecdf:
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$
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xi_#gls("ecdf")^(-1) (tilde(x)) = tilde(x) dot n
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$<eq:ecdf_inverse>
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The result of @eq:ecdf_inverse is the index $i$ of the element $z_i$ from the vector of realizations $bold(z)$.
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The eCDF is constructed through sorting the empirical measurements of a distribution @dekking2005modern. Although less accurate, this method allows a more simple and less computationally complex way to transform real valued measurements into the Tilde-Domain. We will mainly use the eCDF in @chap:smhd because of the difficulty of finding an analytical description for the CDF of a Gaussian-Mixture.
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