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This will require a bit of an ELI5, but what's the advantage of using smaller sub-carriers in different implementations of OFDMA?

In 802.11 ac (OFDM) the subcarrier spacing was 312.5 kHz. In 802.11 ax it is 1/4th of that, 78.125 kHz. In LTE it's only 15 kHz. In 5G, it can be 15, 30, 60, 120, or 240 kHz.

Other than having more "fine" control over resource allocation (assuming smaller resources units as well), what's the advantage of using smaller sub-carriers? Does it increase your throughput? How so?

What's the disadvantage, more potential intersymbol interference, hence a higher SNR requirement?

Please explain your terms a bit if possible, if you bring up things like symbol length or equalization, I don't quite understand those concepts.

RBT
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qbccd
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1 Answers1

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Every subcarrier carries additional bits of data, so the more you can cram in there, the more throughput you get.

If a farmer can reduce the spacing between rows in his field, he can cram in more rows, meaning more plants, meaning higher yields per acre (hopefully).

And yes, making the transmission more complex makes it harder to decode, including harder to separate signal from noise, so higher throughputs generally require higher SNRs.

Spiff
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