3 ms·

This. The standard is also truly horrible to read. It's not really designed to be read, as much as it is an after-the-fact description of what somebody has alre

This. The standard is also truly horrible to read. It's not really designed to be read, as much as it is an after-the-fact description of what somebody has already done. To the point that testing against a very wide variety of base-stations (and the multitudinous variety of configuration options in those base-stations) is mandatory.

mike_hearn 3y ago
Which is presumably hard to impossible without flying around the world with test chips and physically being in those places, as I guess only a handful of carriers can and will reveal all their config settings and software stacks in practice. The more I think about this modem development problem the harder it seems to get. No wonder Apple have struggled and nobody else even seems to try. The amount of tribal knowledge and random hotfixes in the Qualcomm firmware alone must be irreplaceable.
- 8fingerlouie 3y ago
  > Which is presumably hard to impossible without flying around the world with test chips and physically being in those places We had people driving around with our phones logging to a laptop. They basically drove all over the country, trying to cover as much land as possible, and the phone(s) would then attempt to connect to different base stations. The logs from this would be sent back to the developers to investigate failures, and somewhat often a bug would only manifest itself on a single cell tower. Qualcomm has presuably done this work for most of the world, and has subsequently become the benchmark that telcoms calibrate against before deploying cell towers, leading to a more uniform protocol landscape. If Apple hopes to create a new in-house modem chip, they will either need to calibrate it against Qualcomm, or do the gruntwork of travelling the world. In either case, i'm betting that just using Qualcomm chips regardless of the price will be better from an economic perspective. Furthermore, everything GSM is covered by patents of the "big 5" (Motorola, Nokia, Siemens, Ericsson, I forgot the 5th), which at least at the time had free use of the others patents regarding GSM, but *everybody* else implementing GSM hardware and/or software must pay license fees. Qualcomm and Nokia had a big fight over this 3-4 years ago.
  - lstamour 3y ago
    > We had people driving around with our phones logging to a laptop. They basically drove all over the country, trying to cover as much land as possible, and the phone(s) would then attempt to connect to different base stations. Sounds like Apple needs to put test phones inside the cars doing “street view” as well as have Apple Store employees test them.
  - crazygringo 3y ago
    > and somewhat often a bug would only manifest itself on a single cell tower. I can easily understand different brands/products/generations having their quirks, but I'm struggling to imagine what the source of uniqueness could be for a single cell tower. Is it a huge variety of config options, that certain combinations of settings turn out to be rare? Or is it literally just something broken like malfunctioning hardware?
    - 8fingerlouie 3y ago
      > but I’m struggling to imagine what the source of uniqueness could be for a single cell tower. GSM is/was a complex beast. Each base station can only handle 8 simultaneous phone calls (the old 2G/3G multiplexed ones, not modern VoIP), so in crowded areas they’re usually configured with a very short range. Some large conferences have had base stations with their range measured in single digit meters (<30 ft). Furthermore, like WiFi, bandwidth is limited, so base stations are deployed in a “beehive like pattern”, like a triangle with a base station radiating out from each leg, and broadcasting at different frequencies to it’s neighbors. That alone leaves a lot of room for configuration errors on each individual base stations, but when i say “a single cell tower”, i meant on that drive. The bug might be with a specific firmware version of that base station manufacturer, or that particular hardware revision, or simply a configuration error, or maybe it was a bug in our software and/or radio firmware. There are a lot of “moving parts” that needs to be investigated, but from a developer perspective, the error only occurred on one base station. It could of course also turn out to be a “broken” base station, and often enough we would fail to find the error, and had to contact the network operator to get them to help trace down the error.
- Goodroo 3y ago
  Well Huawei seems to have succeeded
  - reic 3y ago
    Huawei invented most of 5G technology and could tailor the 5G standards to their implementations. Which is also why they were first to market with carrier equipment [1] and had the first CPU with an on-chip 5G modem [2]. [1] https://www.wired.com/story/huawei-5g-polar-codes-data-breakthrough/ https://www.wired.com/story/huawei-5g-polar-codes-data-break... [2] https://en.wikichip.org/wiki/Kirin_990 https://en.wikichip.org/wiki/Kirin_990
    - justcradd 3y ago
      No they didn’t. This is utter garbage. I have worked in cellular testing since 1997. The first to market with pre-5G were NTT DoCoMo and Verizon. Huawuei were late to the game. My source is the companies we sold to and I supported personally.
justcradd 3y ago
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mike_hearn 3y ago

Which is presumably hard to impossible without flying around the world with test chips and physically being in those places, as I guess only a handful of carriers can and will reveal all their config settings and software stacks in practice. The more I think about this modem development problem the harder it seems to get. No wonder Apple have struggled and nobody else even seems to try. The amount of tribal knowledge and random hotfixes in the Qualcomm firmware alone must be irreplaceable.

8fingerlouie 3y ago
> Which is presumably hard to impossible without flying around the world with test chips and physically being in those places We had people driving around with our phones logging to a laptop. They basically drove all over the country, trying to cover as much land as possible, and the phone(s) would then attempt to connect to different base stations. The logs from this would be sent back to the developers to investigate failures, and somewhat often a bug would only manifest itself on a single cell tower. Qualcomm has presuably done this work for most of the world, and has subsequently become the benchmark that telcoms calibrate against before deploying cell towers, leading to a more uniform protocol landscape. If Apple hopes to create a new in-house modem chip, they will either need to calibrate it against Qualcomm, or do the gruntwork of travelling the world. In either case, i'm betting that just using Qualcomm chips regardless of the price will be better from an economic perspective. Furthermore, everything GSM is covered by patents of the "big 5" (Motorola, Nokia, Siemens, Ericsson, I forgot the 5th), which at least at the time had free use of the others patents regarding GSM, but *everybody* else implementing GSM hardware and/or software must pay license fees. Qualcomm and Nokia had a big fight over this 3-4 years ago.
- lstamour 3y ago
  > We had people driving around with our phones logging to a laptop. They basically drove all over the country, trying to cover as much land as possible, and the phone(s) would then attempt to connect to different base stations. Sounds like Apple needs to put test phones inside the cars doing “street view” as well as have Apple Store employees test them.
- crazygringo 3y ago
  > and somewhat often a bug would only manifest itself on a single cell tower. I can easily understand different brands/products/generations having their quirks, but I'm struggling to imagine what the source of uniqueness could be for a single cell tower. Is it a huge variety of config options, that certain combinations of settings turn out to be rare? Or is it literally just something broken like malfunctioning hardware?
  - 8fingerlouie 3y ago
    > but I’m struggling to imagine what the source of uniqueness could be for a single cell tower. GSM is/was a complex beast. Each base station can only handle 8 simultaneous phone calls (the old 2G/3G multiplexed ones, not modern VoIP), so in crowded areas they’re usually configured with a very short range. Some large conferences have had base stations with their range measured in single digit meters (<30 ft). Furthermore, like WiFi, bandwidth is limited, so base stations are deployed in a “beehive like pattern”, like a triangle with a base station radiating out from each leg, and broadcasting at different frequencies to it’s neighbors. That alone leaves a lot of room for configuration errors on each individual base stations, but when i say “a single cell tower”, i meant on that drive. The bug might be with a specific firmware version of that base station manufacturer, or that particular hardware revision, or simply a configuration error, or maybe it was a bug in our software and/or radio firmware. There are a lot of “moving parts” that needs to be investigated, but from a developer perspective, the error only occurred on one base station. It could of course also turn out to be a “broken” base station, and often enough we would fail to find the error, and had to contact the network operator to get them to help trace down the error.
Goodroo 3y ago
Well Huawei seems to have succeeded
- reic 3y ago
  Huawei invented most of 5G technology and could tailor the 5G standards to their implementations. Which is also why they were first to market with carrier equipment [1] and had the first CPU with an on-chip 5G modem [2]. [1] https://www.wired.com/story/huawei-5g-polar-codes-data-breakthrough/ https://www.wired.com/story/huawei-5g-polar-codes-data-break... [2] https://en.wikichip.org/wiki/Kirin_990 https://en.wikichip.org/wiki/Kirin_990
  - justcradd 3y ago
    No they didn’t. This is utter garbage. I have worked in cellular testing since 1997. The first to market with pre-5G were NTT DoCoMo and Verizon. Huawuei were late to the game. My source is the companies we sold to and I supported personally.

justcradd 3y ago

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