From 7519c23442d258e039c71dd57d9412e2bc76eebb Mon Sep 17 00:00:00 2001
From: ti_mo <timo.niemann@campus.tu-berlin.de>
Date: Fri, 12 Jun 2026 14:22:18 +0200
Subject: [PATCH] task4 done

---
 lab_4/lab_4.m                            |  4 ++--
 lab_4/link_level_measurements.md         | 15 ++++++++++++
 pnr_snr_cbw.svg => lab_4/per_snr_cbw.svg |  0
 lab_4/task1.m                            | 30 ++++++++++++------------
 4 files changed, 32 insertions(+), 17 deletions(-)
 rename pnr_snr_cbw.svg => lab_4/per_snr_cbw.svg (100%)

diff --git a/lab_4/lab_4.m b/lab_4/lab_4.m
index c2eebb1..cfb54f5 100644
--- a/lab_4/lab_4.m
+++ b/lab_4/lab_4.m
@@ -1,7 +1,7 @@
-% this code is in no manner clean, much code copy because I was lazy
+% this code is in no manner clean
 
 % use these fields to select the task that should be calculated
-do_task1 = true;
+do_task1 = false;
 do_task2 = false;
 do_task3_1 = false;
 do_task3_2 = false;
diff --git a/lab_4/link_level_measurements.md b/lab_4/link_level_measurements.md
index 30e310b..a431ebd 100644
--- a/lab_4/link_level_measurements.md
+++ b/lab_4/link_level_measurements.md
@@ -176,6 +176,21 @@ At very high SNR, pilot tracking can also have little visible impact because the
 
 ## Task 4
 
+#### 4.1
+
+![PER over SNR MCS sweep](per_snr_mcs.svg)
+The MCS sweep shows that higher MCS values require higher SNR to achieve the same packet error rate. Lower MCS values are more robust and can reach PER values around $10^{-3}$ within the simulated SNR range, but this comes at the cost of a lower data rate. For MCS 12 and MCS 13, the PER does not fall below $10^{-1}$ in the observed SNR range. In particular, MCS 13 still shows a high packet error rate around 34 dB SNR where as MCS 0 reaches PER $10^{-3}$, so it is not reliable under these channel conditions.
+
+Reflecting this analysis: Higher MCS values tend to be more sensitive to NTN Doppler and residual CFO.
+
+#### 4.2
+
+![PER over SNR channel bandwidth sweep](per_snr_cbw.svg)
+
+Analyzing the bandwidth sweep, the observed PER improves as the channel bandwidth increases. In this simulation setup, CBW320 reaches a PER of approximately nearly $10^{-3}$ below 10 dB SNR, while CBW20 requires roughly 34-35 dB SNR to reach a comparable PER. This indicates that, for the fixed APEP length and MCS used here, a wider channel bandwidth improves the link robustness in the simulated NTN channel.
+
+So in this simulation a higher bandwith improves PER.
+
 <div style="page-break-after: always;"></div>
 
 ## Task 5
\ No newline at end of file
diff --git a/pnr_snr_cbw.svg b/lab_4/per_snr_cbw.svg
similarity index 100%
rename from pnr_snr_cbw.svg
rename to lab_4/per_snr_cbw.svg
diff --git a/lab_4/task1.m b/lab_4/task1.m
index 9615a45..4af6979 100644
--- a/lab_4/task1.m
+++ b/lab_4/task1.m
@@ -1,11 +1,3 @@
-if use_t1_as_t4
-    mcs_values_t1 = mcs_values;
-    progressTitle = "Task 4.1";
-else
-    mcs_values_t1 = [2];
-    progressTitle = "Task 1";
-end
-
 [cfgEHT, simParameters, channel, chInfo, maxChDelay, satelliteDopplerShift, chanBW] = ...
     create_baseline_configuration(ntn_tdl_delay_profiles(3), bandwidth, false, "None", ...
                        carrier_frequency, 0, ...
@@ -13,14 +5,22 @@ end
                        seed, tx_antenna_count, ...
                        rx_antenna_count, apep);
 
-meanSlantRange = mean(slantRanges);
-meanSatelliteDopplerShift = mean(dopplerShifts);
-meanNormalizedCFO = meanSatelliteDopplerShift / wifi_be_subcarrier_spacing;
+if use_t1_as_t4
+    mcs_values_t1 = mcs_values;
+    progressTitle = "Task 4.1";
+else
+    mcs_values_t1 = [2];
+    progressTitle = "Task 1";
 
-disp("Mean Elevation Angle: " + meanElevationAngle + "°")
-disp("Mean Slant Range: " + meanSlantRange + "m")
-disp("Mean Satellite Doppler Shift: " + meanSatelliteDopplerShift + "Hz")
-disp("Normalized CFO: " + meanNormalizedCFO)
+    meanSlantRange = mean(slantRanges);
+    meanSatelliteDopplerShift = mean(dopplerShifts);
+    meanNormalizedCFO = meanSatelliteDopplerShift / wifi_be_subcarrier_spacing;
+
+    disp("Mean Elevation Angle: " + meanElevationAngle + "°")
+    disp("Mean Slant Range: " + meanSlantRange + "m")
+    disp("Mean Satellite Doppler Shift: " + meanSatelliteDopplerShift + "Hz")
+    disp("Normalized CFO: " + meanNormalizedCFO)
+end
 
 errorCounts = zeros(numel(mcs_values_t1), numel(snrs));
 packetCounts = zeros(numel(mcs_values_t1), numel(snrs));