diff --git a/lab_5/leo_satellite_pass.md b/lab_5/leo_satellite_pass.md index 4cb9c16..60ce072 100644 --- a/lab_5/leo_satellite_pass.md +++ b/lab_5/leo_satellite_pass.md @@ -16,6 +16,50 @@ Analyzing a LEO Satellite Pass by Timo Niemann

+## Reproducibility +> '-' means use the last non '-' left value + +| Reproducibility factor | Task 1 value | Task 2 value | Task 3 value | Task 4.1 - 4.3 value | Task 4.4 value | Task 4.5 - 4.6 value | +|:---|:---:|:---:|:---:|:---:|:---:|:---:| +| MATLAB Version | 26.1.0.3251617 (R2026a) Update 2 | - | - | - | - | - | +| 5G Toolbox Version | 26.1 | - | - | - | - | - | +| WLAN Toolbox Version | 26.1 | - | - | - | - | - | +| Communications Toolbox Version | 26.1 | - | - | - | - | - | +| Parallel Computing Toolbox Version | 26.1 | - | - | - | - | - | +| Satellite scenario start time | 2026-06-17 08:00:00 | - | - | - | - | - | +| Satellite scenario duration | 2 h | - | - | 10 min | - | - | +| Satellite scenario sample time | 30 s | - | - | - | - | - | +| Ground station | 52.515744683039436 deg lat, 13.325825073341306 deg lon, 37 m altitude | - | - | - | - | - | +| Orbit propagator | two-body-keplerian | - | - | - | - | - | +| LEO altitude | 600 km | - | - | - | - | - | +| Eccentricity | 0 | - | - | - | - | - | +| Inclination | 90 deg | - | - | - | - | - | +| RAAN | 42 deg | - | - | - | - | - | +| Argument of periapsis | 32 deg | - | - | - | - | - | +| True anomaly | 0 deg | - | - | - | - | - | +| Random stream | mt19937ar with seed | - | - | - | - | - | +| Random seed | 666 | - | - | - | - | - | +| NTN profile | not used | NTN-TDL-C | - | - | - | - | +| Delay spread | not used | 30 ns | - | - | - | - | +| Carrier frequency | 2.4 GHz | - | - | - | [2.4 5 6 10 20 40 45 50 55 60] GHz | - | +| Channel bandwidth | not used | 20 MHz | - | - | - | - | +| MCS | not used | 3 | - | - | - | - | +| APEP length | not used | 1000 B | - | - | - | - | +| TX/RX antennas | not used | 1-by-1 SISO | - | - | - | - | +| Transmit power | not used | 20 dBm | - | - | - | - | +| Free-space path loss | not used | enabled | - | disabled | - | - | +| WiFi sensitivity threshold | not used | -85 dBm | - | not used | - | - | +| Reliable receive threshold | not used | -75 dBm | - | not used | - | - | +| Amplifier gain assumption | not used | 30 dB | - | not used | - | - | +| SNR vector | not used | not used | not used | $0:1:40\,dB$ | - | - | +| Packet budget | one access-analysis sample every 30 s | power-only pass over all access-analysis samples | reused from Task 2 | 1000 packets per SNR point | - | no additional simulation | +| Packet timing | full 2 h scenario grid | - | - | 1000 uniformly spaced packets over 10 min | - | - | +| Pre-compensation cases | not used | not used | not used | none, ideal, 10 Hz, 100 Hz, 1000 Hz, 5000 Hz residual CFO | none, ideal | uses Task 4.1 - 4.4 results | +| Pilot tracking | not used | default receiver behavior | - | disabled | - | - | +| Receiver CFO correction | not used | coarse and fine preamble-based CFO correction active | - | - | - | - | + + + ### Task1 #### 1.1 @@ -30,12 +74,16 @@ To calculate the distance to the satellite, the MATLAB access analysis example w The first satellite flyby occurs at around 08:05:30. During the pass, the distance first decreases as the satellite approaches the ground station and then increases again after the closest approach. Around 08:53:30 to 08:54:00, the distance reaches a maximum because the satellite is on the far side of its orbit relative to the ground station. The second pass occurs at around 09:42. Its minimum distance is larger than during the first pass because Earth's rotation changes the relative position of the ground station below the satellite orbit. + + #### 1.3 ![Elevation angle over time sweep](elevation_angle_over_time.svg) As in the distance plot, the elevation angle reaches its highest value during the first pass. The second pass has a lower maximum elevation because Earth's rotation shifts the ground station relative to the satellite ground track. + + ### Task2 #### 2.1 @@ -219,6 +267,8 @@ The blue line shows the Doppler shift returned by MATLAB's `dopplershift` functi In this scenario, Doppler shift can support localization because it constrains the relative radial motion between satellite and ground station. However, Doppler alone is not sufficient for unique localization: the satellite orbit, time, and additional measurements such as range or elevation are still required. + + ### Task4 #### 4.1 - 4.3 @@ -231,10 +281,26 @@ Only small differences between the curves are visible. The maximum PER differenc A likely reason is that the 802.11 receiver still performs coarse and fine CFO correction using the WiFi preamble. Pilot tracking is disabled as required by the task, but the preamble-based CFO correction is still active. Because of this, even the case without transmitter-side pre-compensation can still decode many packets successfully. The additional benefit of ideal pre-compensation is therefore limited at the simulated 2.4 GHz carrier frequency. + + #### 4.4 -For this compare only the test with ideal pre-compensation and without pre-compensation is run. +![PER over SNR sweep with Frequency sweep](per_over_snr_freq.svg) + +For this compare only the test with ideal pre-compensation and without pre-compensation is run. The simulated frequencies are 2.4GHz, 5GHz, 6GHz, 10GHz, 20GHz, 40GHz, 45GHz, 50GHz, 55GHz and 60GHz. For the simulation without pre-compensation the maximum carrier frequency that does not degrade in quality in contrast to the optimal is 20GHz, the next tested 40GHz frequency resulted in only reaching below 0.8 PER in the simulated SNR range instead of well below 0.1 PER. With pre-compensation the simulation did not reach cutoff, all testet frequencies performt wellenough to be used as carrier frequencies for WiFi. + +#### 4.5 + +The PER curves from 4.1 - 4.3 show that residual CFOs up to 5kHz do not cause a strong degradation. The simulated 802.11be receiver can tolerate at least about 5 kHz residual CFO after Doppler pre-compensation. This corresponds to 6.4% of the 78.125kHz subcarrier spacing of a 20MHz EHT waveform. The reason is that pilot tracking is disabled, but the receiver still performs coarse CFO estimation using the preamble. Therefore, transmitter-side pre-compensation does not need to be perfect. Errors in the low-kHz range are still corrected well enough in this simulation. + +#### 4.6 + +Following the mentions in this [paper]: +Required information: carrier frequency, relative radial velocity along the line-of-sight, positions and velocities of transmitter and receiver, timing, and separation of Doppler from oscillator frequency offset. + +How obtained: The required information can be obtained from satellite ephemeris (data collection of calculated positions of a celestial object at regular intervals in this case the satellite) or TLE data, known ground-station coordinates or receiver GNSS feedback, and a synchronized time reference. Using these values together with the carrier frequency, the transmitter can estimate the relative range rate and calculate the Doppler shift before transmission. #### Special Thanks - +

This lab was solved with contribution of GPT 5.5. +

diff --git a/lab_5/per_over_snr_freq.svg b/lab_5/per_over_snr_freq.svg index bc0145b..cca1642 100644 --- a/lab_5/per_over_snr_freq.svg +++ b/lab_5/per_over_snr_freq.svg @@ -1,6 +1,6 @@ - Qt SVG Document MATLAB, The MathWorks, Inc. Version 26.1.0.3251617 R2026a Update 2 @@ -8,1652 +8,2220 @@ - - + - - + - - - - - - - - - - - - - - - - - - - - + + + + + + + + + + + + + + + + + + + - SNR [dB] - - - - - - - - - - - + + + + + + + + + + - 0 - 5 - 10 - 15 - 20 - 25 - 30 - 35 - 40 - PER - - - - - - - - - - - - + + + + + + + + + + + - 0.1 - 0.2 - 0.3 - 0.4 - 0.5 - 0.6 - 0.7 - 0.8 - 0.9 - 1 - Pre-compensation: none - - + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + - - + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + - - + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 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5 GHz - 6 GHz - 10 GHz - 20 GHz - +40 GHz + + + +45 GHz + + + +50 GHz + + + +55 GHz + + + 60 GHz - - + diff --git a/lab_5/task4.m b/lab_5/task4.m index 72454a7..bbe6440 100644 --- a/lab_5/task4.m +++ b/lab_5/task4.m @@ -137,8 +137,7 @@ end % calc_task4 % 4.4 -% carrierFrequenciesF = [2.4e9, 5e9, 6e9, 10e9, 20e9, 60e9]; -carrierFrequenciesF = [20e9, 40e9, 60e9, 80e9, 120e9, 240e9]; +carrierFrequenciesF = [2.4e9, 5e9, 6e9, 10e9, 20e9, 40e9, 45e9, 50e9, 55e9 60e9]; preCompensationsF = {"none", "ideal"}; preCompensationLabelsF = [ "none"