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Comment by Aardwolf | Hacker News Reader

How come that 5G is part of a feature set of a CPU? Is 5G implementable in software?

It's not a feature set of a CPU, this is an SOC, or System On Chip. It's not like an Intel 4004 that just does the processing and relies on external chips for peripherals, they bake in all the typical stuff that the system it's designed for (a cell phone) is expected to use. It contains 8 ARM cores (one of which is "the CPU"), a GPU, an AI DSP, a memory controller, 3 image signal processors for connection to cameras, video encoder/decoders, Bluetooth, Wifi, NFC, GPS/GNSS, dual SIM support, probably some general-purpose inputs and outputs, plus, yes, a 5G modem.

To sum up the explanations given for why it's part of the SOC and not an external device on a bus:

> Last year’s ... external 5G modem such as the X55 helped the 5G transition as it was available to vendors earlier than the Snapdragon 865 SoC itself, allowing them to design their RF systems before having access to the newest SoC.

> The platform’s reabsorption of the modem into the SoC die should signify better power efficiency, lower platform cost as well as lower PCB complexity for smartphone vendors.

How does this compare to the latest A14 (i think that's the latest) when it comes to "baked in" radio set? Is it still external on apple device and it's just a matter of time until they bake in what they acquired from Intel?

Or are they already baking it in and just paying royalties to Qualcomm?

Apple use a separate modem chip. iPhone12 has a Qualcomm SDR865 baseband and SDX55M radio. There have been rumours about Apple making their own modem, and presumably integrate it in an A-series SoC, but nothing yet.

A 5G modem is pretty complicated tech. I used to work on Nvidia's Icera, but that's gone now. A lot of chip makers have given up, and Qualcomm is the undisputed leader. MediaTek dominates in low-mid end Androids. I think Huawei & Samsung both have something.

The A14 uses an external Qualcomm radio, much like Android phones based on the previous Qualcomm Snapdragon 865. Take a look at the yellow and green boxed SDR865 and SDX55M in this image of the iPhone 12 with A14 motherboard from the iFixit teardown:

https://www.ifixit.com/Teardown/iPhone+12+and+12+Pro+Teardow...

The same are in yellow and red on the Samsung Galaxy S20 with Snapdragon 865 teardown:

https://www.ifixit.com/Teardown/Samsung+Galaxy+S20+Ultra+Tea...

The SDR865 and SDX55M are the external 5G parts that would disappear with the 888. Compare the PCB area used for those (they're both almost as large as the whole SOC; I'm sure much of that is driven not by silicon area or thermal requirements but by a lot of power and pins for high-speed host communication) to this teardown of the Galaxy S10, which has the Snapdragon 855 with an integrated 4G modem:

https://www.ifixit.com/Teardown/Samsung+Galaxy+S10+and+S10e+...

Apple has said they want to integrate the 5G modem by 2022.

Apple bought Intel’s modem division in 2019. That purchase included related patents. The expectation is that they will move to integrate their own modems into their SOC in the next couple of years. That will help increase the efficiency of their chips.

It may also make it feasible to include 5G in laptops. Currently Apple licenses Qualcomm modems. Qualcomm charges a fee that is proportional to the full retail price of the device. That would be significant for a laptop. If Apple can use their own modems and get around that licensing cost, it makes a laptop with a cellular connection more likely.

Almost all modern modems do a ton of work in software on specialised DSPs.

Trying to do a wholly SDR free 5G modem would be a monumental feat, and first attempts at implementations would probably be gigantic.

More importantly, it would almost certainly be a broken implementation, without the ability to be updated. 5G is extremely complex, even when processing in software.

Not in real time.

If you want to do real time 5G calls (as you do when you prototype, test and develop) using software defined radio you buy one of those USRP boxes. They have CPU's DSPs that run software and then programmable FPGA's talking to ADCs and DACs.

Where can I find more information about the details of the interface of the modem firmware (ASIC) and the real time software?

Call up Qualcomm and offer millions of dollars?

Here is an interesting paper on the architecture of an LTE modem. Seems like a reasonable approach, although I don't know how prevalent this approach is. RFIC, some dedicated hardware for the PHY DSP stuff and an ARM chip for the high level logic, all connected via AXI bus.

https://community.arm.com/cfs-file/__key/telligent-evolution...

There‘s also Amarisoft, which does it in „real time“ in software, but not open source.

I believe srsLTE, used to turn SDRs into eNodeB/UEs, adds support for 5G soon (tm).

Read the article.

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