Start doc on fading channels

2 files changed, 71 insertions, 0 deletions

diff --git a/doc/thesis/figures/tikz/multipath-impulse-response.tex b/doc/thesis/figures/tikz/multipath-impulse-response.tex
new file mode 100644
index 0000000..4826b6f
--- /dev/null
+++ b/doc/thesis/figures/tikz/multipath-impulse-response.tex
@@ -0,0 +1,34 @@
+% vim: set ts=2 sw=2 noet:
+\tdplotsetmaincoords{70}{40}
+\begin{tikzpicture}[tdplot_main_coords, font = \footnotesize\ttfamily]
+	\draw[thick, -latex] (0,0,0) -- node[sloped, midway, below, gray] {Effect of the channel} (7,0,0) node[right] {\(t'\)};
+	\draw[thick, -latex] (0,0,0) -- node[sloped, midway, above, gray] {How the channel changes} (0,7,0) node[right] {\(t\)};
+	\draw[thick, -latex] (0,0,0) -- (0,0,2) node[above] {\(h(t,t')\)};
+
+	\foreach \y in {1,2,...,4}{
+		\draw[dashed, gray] (0,1.5*\y,0) -- ++(7,0,0);
+	}
+
+	\foreach \x in {1,2,...,6}{
+		\draw[dotted, gray] (\x,0,0) -- ++(0,7,0);
+	}
+
+	% draw 4 responses
+	\begin{scope}[very thick, -{Circle[fill=white]}]
+		\foreach \x/\v in {.8/1, 2.2/2, 2.9/1, 4/4, 5.1/7, 5.8/3}{
+			\draw[blue!80!red] (\x,1.5*4,0) -- ++(0,0,\v/3);
+		}
+
+		\foreach \x/\v in {.9/2, 2.1/2, 3/1, 4/3, 5/6, 6/3}{
+			\draw[blue!60!red] (\x,1.5*3,0) -- ++(0,0,\v/3);
+		}
+
+		\foreach \x/\v in {.6/1, 2/1, 2.8/3, 4.1/4, 5.5/4, 6.2/1}{
+			\draw[blue!40!red] (\x,1.5*2,0) -- ++(0,0,\v/3);
+		}
+
+		\foreach \x/\v in {1.1/2, 1.8/1, 3/2, 3.7/1, 4.8/3, 5.8/1}{
+			\draw[blue!20!red] (\x,1.5,0) -- ++(0,0,\v/3);
+		}
+	\end{scope}
+\end{tikzpicture}
diff --git a/doc/thesis/figures/tikz/multipath-sketch.tex b/doc/thesis/figures/tikz/multipath-sketch.tex
new file mode 100644
index 0000000..096f06f
--- /dev/null
+++ b/doc/thesis/figures/tikz/multipath-sketch.tex
@@ -0,0 +1,37 @@
+% vim: set ts=2 sw=2 noet:
+\begin{tikzpicture}[
+			antenna/.pic = {
+				\draw[very thick] (0,0) -- ++(2mm, 3mm) -- ++(-4mm,0) -- cycle;
+				\draw[very thick] (0,0) -- ++(0,-5mm) coordinate (-mast) {};
+				\draw[thick] (0,0) -- ++(0,3mm);
+				\node[inner sep = 0pt, outer sep = 6pt] (-center) at (0,2mm) {};
+			},
+	]
+
+	% Antennas
+	\draw (0,2) pic (T) {antenna} node[above left = 3mm] {\sffamily\bfseries TX};
+	\draw (5,0) pic (R) {antenna} node[above right = 3mm] {\sffamily\bfseries RX};
+
+	% wall coefficients
+	\draw[thick] (4.75, 2.25) to[out = -20, in = 180] ++(1.2,-.5) node[right] {\(|\Gamma| > 0\)};
+
+	% walls
+	\draw[thick, fill = lightgray!20] (3,2) -- ++(2,-.5) -- ++(0,1) -- ++(-2,.5) -- cycle;
+	\draw[thick, fill = lightgray!20] (-1,0) -- ++(3,0) -- ++(1,-.5) -- ++(-3,0) -- cycle;
+
+
+	% reflected signals
+	\draw[line width = 2pt, blue!50!white, -latex] (T-center) -- node[above, pos = .5] {\(\tau_2\)} (4,2.25) -- (R-center);
+	\draw[line width = 2pt, blue!50!white, -latex] (T-center) -- node[left, pos = .7] {\(\tau_3\)} (1,-.25) -- (R-center);
+	\draw[line width = 2pt, blue!50!white, -latex] (T-center) -- node[above, pos = .5] {\(\tau_4\)} (-2.5,1.5) -- (R-center); 
+
+	% another wall
+	\draw[thick, fill = lightgray!20] (-2,0) -- ++(-1,.5) -- ++(0,2) --++(1,-.5) -- cycle;
+
+	% LOS path
+	\draw[line width = 1mm, red!50!white,
+		decorate, decoration = {
+			expanding waves, angle = 5, segment length = 2mm
+		}
+	] (T-center) -- node[above = 2mm, pos = .5] {\(\tau_1\)} (R-center);
+\end{tikzpicture}