I would add a possible full duplex repeater mode, similar to how a DOCSIS cable modem operates. Cable modems (CM) only communicate with a specialized router known as a Cable Modem Termination System (CMTS). The CMTS downstream carrier imbeds data describing how and when a CM can communicate to establish communications. This data includes transmit frequencies, modulation types supported and TDMA timing sync data. Some of the TDMA time slots are reserved for "ranging" opportunities, similar to a net controller calling out for any station who wants to call in now. Once a modem is heard from the CMTS will allocate a "mini slot" for that CM and begin fine tuning the timing, modulation and transmit power level. When the CMTS and CM reach détente (usually a few seconds) the data-specific and authentication data is exchanged, and the CM will start passing data to the customer equipment. Note that operators will offer several upstream (and downstream) modulation formats to allow for older modems and cable craft issues, etc.
The repeater could periodically advertise frequencies it is listening on and when to transmit. This would allow for cross-banding on many different bands, such as 1.2 GHz and 222 MHz but also allow for 2M/70CM users to get their feet wet, possibly at lower transmit speed. and modulation handshaking for weaker signals while optimizing the repeater output channel with higher modulation rates, assuming a high power amplifier would be installed, optimized location and antenna systems, etc. While automating the handshake process is probably a little too much take on for amateurs, by baking in cross-band and separating RF input from RF output from the start it opens the door to the possibility down the road.
That's an interesting list of requirements, but there is some layering required. Don't throw file compression, link setup, routing, all into one bucket. Modulation is the most important thing to get right. It enables everything else. Then add ALE, FEC and ARQ as required. Build something state of the art, not a rip of some other code made for some other purpose because it's convenient. Go through extensive on-air testing with a rigorous methodology for evaluation and improvement. Take the best of the best and improve it for the ham radio environment.
Also allow, but don't limit to R-pi 4. If better communications can be done with a top-end processor and a fast GPU, then have at it, but be backward compatible. Baseband sound-card modes and I/Q modes are possible with the same software. It's just a little bit of math to go from one to the other. Get manufacturers to build custom silicon (with firmware update capability) and include it in their radios.
Might take a bit of organization :-)
By the way, OFDM has been around long before 5G. It was used in 3G, LTE, Wifi, etc.
73,
Chris VE3NRT
P.S. Good edition this time. I see I'm going to have to reread everything. Lots of good pointers to follow up. So thanks.
I would add a possible full duplex repeater mode, similar to how a DOCSIS cable modem operates. Cable modems (CM) only communicate with a specialized router known as a Cable Modem Termination System (CMTS). The CMTS downstream carrier imbeds data describing how and when a CM can communicate to establish communications. This data includes transmit frequencies, modulation types supported and TDMA timing sync data. Some of the TDMA time slots are reserved for "ranging" opportunities, similar to a net controller calling out for any station who wants to call in now. Once a modem is heard from the CMTS will allocate a "mini slot" for that CM and begin fine tuning the timing, modulation and transmit power level. When the CMTS and CM reach détente (usually a few seconds) the data-specific and authentication data is exchanged, and the CM will start passing data to the customer equipment. Note that operators will offer several upstream (and downstream) modulation formats to allow for older modems and cable craft issues, etc.
The repeater could periodically advertise frequencies it is listening on and when to transmit. This would allow for cross-banding on many different bands, such as 1.2 GHz and 222 MHz but also allow for 2M/70CM users to get their feet wet, possibly at lower transmit speed. and modulation handshaking for weaker signals while optimizing the repeater output channel with higher modulation rates, assuming a high power amplifier would be installed, optimized location and antenna systems, etc. While automating the handshake process is probably a little too much take on for amateurs, by baking in cross-band and separating RF input from RF output from the start it opens the door to the possibility down the road.
That's an interesting list of requirements, but there is some layering required. Don't throw file compression, link setup, routing, all into one bucket. Modulation is the most important thing to get right. It enables everything else. Then add ALE, FEC and ARQ as required. Build something state of the art, not a rip of some other code made for some other purpose because it's convenient. Go through extensive on-air testing with a rigorous methodology for evaluation and improvement. Take the best of the best and improve it for the ham radio environment.
Also allow, but don't limit to R-pi 4. If better communications can be done with a top-end processor and a fast GPU, then have at it, but be backward compatible. Baseband sound-card modes and I/Q modes are possible with the same software. It's just a little bit of math to go from one to the other. Get manufacturers to build custom silicon (with firmware update capability) and include it in their radios.
Might take a bit of organization :-)
By the way, OFDM has been around long before 5G. It was used in 3G, LTE, Wifi, etc.
73,
Chris VE3NRT
P.S. Good edition this time. I see I'm going to have to reread everything. Lots of good pointers to follow up. So thanks.