Week 3 Progress Update
AI-Driven Autonomous Communication Discovery and Link Selection for Lunar Surface Rovers
Jonathan Morcos
WINLAB Summer Internship
Week 3
Results + modulation learning
16-QAM / OFDM
Focus: connect link-selection simulation with basic RF signal generation concepts.
Simulation Results
WINLAB weekly update
Selected link share
LTE/5G
85.30%
Earth
8.70%
Relay
3.80%
Orbiter
2.20%
91.60%
Availability ratio
8.40%
Outage probability
208.21 ms
Average selected delay
24.58 dB
Average selected SNR
How to read this slide
Left: how often each link was chosen. Right: overall quality of the selected links. The main result is that LTE dominates, but outages still happen when no link is usable.
Result Plots
WINLAB weekly update
Selected link over time
Shows which link the rover picked at each time step.
Delay over time
Spikes mean the selected link had higher delay.
SNR over time
Higher SNR means a cleaner selected signal.
Selection counts
Confirms LTE/5G was chosen most often.
Threshold vs. handovers
Shows handovers dropping as switching becomes stricter.
16-QAM Learning Demo
WINLAB weekly update
What I built
Generated random bits in Python.
Mapped groups of 4 bits into 16-QAM symbols.
Placed the symbols onto OFDM subcarriers.
Saved plots for constellation, waveform, and spectrogram.
16-QAM
16 possible points
Why this matters
The rover project is about choosing communication links. This RF demo helps me understand what digital communication signals look like once data is actually modulated onto a waveform.
16-QAM Constellation
WINLAB weekly update
How to read it
Each point is a possible symbol.
Horizontal direction is the In-Phase (I) component.
Vertical direction is the Quadrature (Q) component.
The receiver estimates which point was sent.
Key idea
A constellation is like a map of digital symbols. Cleaner clusters usually mean the receiver can decode the data more reliably.
OFDM Waveform
WINLAB weekly update
Real part of OFDM waveform
What happened in the code
Used 64 OFDM subcarriers.
Used an IFFT to convert frequency-domain symbols into a time waveform.
Added a cyclic prefix of 16 samples to each OFDM symbol.
What the waveform shows
The waveform is not supposed to look like individual bits. It is the combined signal after many subcarriers are added together in time.
RF Spectrogram
WINLAB weekly update
RF spectrogram of OFDM signal
What the plot means
x-axis: time, so we can see when the signal is present.
y-axis: frequency, so we can see where the signal energy is located.
color: power in dB, where brighter colors mean stronger energy.
This is closer to what SDR tools show: energy over frequency and time.
Week 3 Takeaway
WINLAB weekly update
Main takeaway
The link selector results show which communication option the rover chooses over time.
The 16-QAM constellation shows how bits become modulation symbols.
The OFDM waveform and spectrogram show how those symbols become a signal over time and frequency.
Next step: connect simulated link selection ideas with more realistic RF/SDR measurements.