Figure: PLC vs VLC throughput
The light link is the bottleneck
Summary sentence to be added.
Internet delivered through light, carried to the room by your mains wiring.
Power Line Communication moves data fast over the wires already in the walls. Visible Light Communication then hands it to a device through a lamp. We are building and testing the link between the two.
How it works
Data takes three steps from the router to your device. The mismatch between the first and last is the interesting part.
1. Over the power line
HomePlug adapters send data through the mains wiring. It is fast, but interference makes it arrive in bursts, with short dropouts.
2. Through a buffer
A small memory holds data while the power line is busy and releases it at the pace the light link can take.
3. Out through light
An LED flickers too fast to see and carries the data to a photodiode. Reliable, but much slower than the wire.
Size the buffer
The power line stalls now and then, then sends everything it was holding at once. Choose how much memory the buffer gets. Too little and data is lost in the burst. Memory costs money and chip space, so find the smallest size that keeps losses under 1%.
power line downbuffer fillbuffer sizedata lost
–data lost
–peak buffer fill
–worst added delay
–longest dropout
Placeholder model: illustrative data, not our measurements. It will be replaced with traces recorded on our bench. Every visitor sees the same dropouts for a given interference level, so sizes can be compared fairly.
What we found Placeholder
Results from our investigation will appear here as they are finalised.
Figure: dropout durations
How the power line fails
Summary sentence to be added.
Figure: performance under noise
Where the system breaks
Summary sentence to be added.
The team
[Team member names and roles]
Supervisor: [name]
School of Electrical and Information Engineering, University of the Witwatersrand.
Photo: bench setup