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Comment by tristanj | Hacker News Reader

According to this forum post [0], the Tesla Navigation data is 5-8 GB in size. This is a large file to download over a cellular network, and I can understand why Tesla/Carriers would prefer people download this file over wifi or wired internet.

Apple has had a related download policy: they won't let you download major iOS updates over cellular data, and require wifi or USB data cable to install them. I believe Apple does this as a result of carrier pressure, however I don't think Apple has publicly stated this (Apple rarely does so).

A lot of people seem to forget that cellular bandwidth is finite, and that wireless congestion is a real problem today.

[0] https://teslamotorsclub.com/tmc/threads/firmware-update-2018...

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Is Tesla not big enough to negotiate off-peak discounts? Do US carriers not support that type of thing? It's such an obvious solution I can't believe they don't do it.

When I visited Sri Lanka, $8 at the airport got me a SIM card and something like 16 GB of data. ~4GB during the day, and the rest at night. So blatantly rational.

Wireless congestion is not a problem at 3am. I've worked at an ISP long enough to know what consumer access patterns look like.

>Apple has had a related policy: they won't let you download major iOS updates over cellular data, and require wifi or USB data cable to install them. I believe this is a result of carrier lobbying, however I don't think there is an official reason (Apple rarely has one).

Common sense really. Apple would get two complaints if they didn't do this. 1. From people who blew through their data allowances pulling the update. 2. From the networks and everyone else once the network bogs down every update. (Apple doesn't stage rollout like most manufacturers do)

Related: The 11.2 update had carrier specific modifications made to wifi calling. On networks where congestion was a bigger problem, wifi calling gets preferred. On networks with coverage issues, but less congestion... cellular is preferred if it's there.

>A lot of people seem to forget that cellular bandwidth is finite, and that wireless congestion is a real problem today.

They also seem to think Tesla would get some sort of a deal from the networks for all this bulk data.

But there should be a setting in iOS to disable this requirement of wifi to install updates. For people who have unlimited 4G and no wifi/ethernet.

I only have unlimited 4G SIM and all my internet usage is either on my phone or through my other devices using mobile hotspot. I don't want to pay extra money to carriers for home broadband with wifi since I already have super fast unlimited mobile connection (it's fast enough for Twitch/Netflix streaming so I really don't need dedicated line).

I'd like to make this configurable so people like me don't have to go to Starbucks or other places with public wifi to download updates.

iOS doesn't lack such a setting because of an oversight for the past nine years. To carriers, there is no such thing as "unlimited" internet.

Depends on the time. I'm happy carriers wouldn't mind downloads as long as they happen between 1am-5am. Apple could introduce a feature to allow cell downloads but only do so during off-peak hours.

>But there should be a setting in iOS to disable this requirement of wifi to install updates.

You missed complaint #2. While your plan says unlimited, physics doesn't work that way. It's only fast right now because people aren't pulling large update files in all at the same time. I would not want to be in a populated area trying to use the network on update day. Rush hour at train stations is bad enough...

It's a pretty crude mechanism, though. A better system would have the tower tell the phone if it's overloaded or not - or, ideally, the available bandwidth - and the phone would decide whether to download it now or later.

There's more to congestion than just the particular tower you're connected to though.

I do find that highly unlikely though. I sometimes am using dozens or hundreds of GBs in streaming over a week and never got throttled so far.

I’d assume few hundred MBs or even few GBs of updates every couple of weeks can’t be of significance.

I think Netflix, YouTube and Twitch traffic are much bigger concern for carriers.

I connect my phone via my 4G router when I need to large stuff from Apple, and it hurts my soul every time

What happens if you make a WiFi hotspot and download it to a device over that?

That’s a workaround. I can connect my MacBook Pro to my iPhone hotspot over Bluetooth and download updates on desktop iTunes app because MacBook think it’s using WiFi even though in reality it’s all 4G. Then I can download and install updates to the iPhone from iTunes. Crude workaround but it’s possible.

Yeah sure. What they really need to do is proper delta-updates, not download the full navigationData file.

While you’re not wrong, it’s not necessarily under Tesla’s control if they can do so (do they build and manage their own map data files?) and even if it was, managing an update that supports delta patches is its own headache that comes with extra engineering and testing costs, so maybe in the end the extra cost would be comparable?

We’re only talking about 200k clients here, unlike Google in which each byte of bandwidth reduction is multiplied by hundreds of millions of phones.

You don't need to build your own files to do a delta. You just take the old file and the new one, and you calculate a binary diff using cperciva's bsdiff or Google's courgette.

Then on the car you take the old file and the diff to generate the new file.

Off-topic, but thanks for reminding me about bsdiff [1], it's quite cool. Not something I have had a reason to use, but something I enjoy knowing about.

Also, it's wonderful that the web page about it uses a Pentium at 200 MHz as the performance reference platform (at 45 KB/s). :)

[1] http://www.daemonology.net/bsdiff/

But you have to carefully check which version is currently there before you apply the delta, to make sure it's applicable. Also make sure previous delta was fully applied and not stopped halfway through etc etc. It really is not as trivial as you make it sound, hence the extra engineering burden mentioned in comment above.

OK, but if they're a good member of the tech community, they should put in that effort and/or charge their own customers appropriately. Not just punt on it and exploit somebody else's free service.

But then they also need to download other large files regularly. So I think their policy is to tell people to do it over wifi, and most people can do that, because their car sits in a garage or near a house all night. Seems sensible, no? Why take the risk of messing about with deltas when most customers manage fine.

They are already much better members of the tech community than most car manufacturers. I have to make an appointment with my dealer and leave my car there for a few hours if I want a map update for my navigation system and I have to pay an unreasonable amount of money for it.

I think what people are asking here is too much; it’s not an unrealistic expectation that someone to find wifi occasionally in order to receive free updates.

You already have to check if the file was correctly downloaded over Wifi and not stopped halfway or tampered with. There's no new requirement here.

You do have to compare if the old file is the correct, but not only is that extremely basic (I mean, it's comparing a filename), even if you manage to muck it up, the previously mentioned check will make sure the incorrectly generated file won't be applied, since the signature won't be valid.

You're assuming each different version of this map database will have a different filename? I dont think you've thought this through. Everything in software engineering seems simple if you dont look at the details. You're saying it would be easy to do deltas. I'm saying its not as easy as you think, and secondly why should they bother when there's probably a thousand more important requirements on their to-do list right now. Thats whats real-world projects are like.

You're assuming each different version of this map database will have a different filename?

It'll have whatever Tesla wants it to have. Even if they receive the file as a binary blob, they can attach whatever metadata they want when transferring it to the car. A filename would just be what I'd use, but the specific format is irrelevant.

Everything in software engineering seems simple if you dont look at the details. (...)

And some actually are. But in any case, I never actually said it was simple. I rebutted specific reasons you gave. Is it complicated for other reasons? Sure, maybe, who knows.

That may not work if the file is compressed, depending on how the compression works.

An effective delta-based update strategy requires planning and implementation that anticipates such a system; otherwise you’re going to end up with diffs that are not significantly smaller than the original files.

I’m sure they do generally, but this particular update is to an entirely new navigation database.

My understanding is that the new database uses vector rendering rather than rendering image tiles and it’s supposed to be much better than before.

This is also why so many Tesla owners are so keen to switch over to it.

delta-updates, agree. whole discussion is wrong. why do customers need to download multiple gigs of shit all the time? makes no sense. it's not like the map of the world completely changes all the time. perhaps some subtle updates to routes and roads. you could do with just pushing a limited set of data, probarbly not more than a few mb if even so much.,..

On Windows 10, you can mark a wifi connection as metered so that Windows won't download updates using this connection.

That is a nice feature.

It is absolutely necessary. Windows will happily downloads tens of GB worth of updates (or, you know, a full OS that MS is trying to push on you) without the user being able to do anything about it.

The 'wifi' may be a 4G router or another phone, makes sense.

It will download the updates anyway if you only use metered connections for long enough.

Nope. I've stayed months with only a metered connection and Windows did not download anything. And when I switched to non-metered, I got something like 10 Go of updates on one go.

But I don't if other software, including other Microsoft products, respect this indication.

Even on iOS's App Store, you cannot download apps over 150MB using cellular. I thought this was actually mandated by the carriers (who were concerned in early days that app downloads would overly congest their network) and wouldn't be surprised if Tesla has similar restrictions as part of their carrier agreement.

EDIT: Weird, I thought when I first hit reply, there was no mention of App Store, but I see we're on the same page with this one :)

I wonder why is it that large maps update? Is it for whole US maps? If it is, I imagine to just update my local region instead of many other regions or I could choose to update manually myself later. Basically why not break the update to many smaller pieces and let user update the most important.

Or just use delta updates.

Probably because the current solution is much simpler, and works better in the majority of cases. I wouldn't want to worry before going for a long drive, whether all my maps data has been updated or not. Since my car is connected to wifi all night long, I'd expect it to download as much data as it might need, so if I suddenly decide to take a road trip, I'm prepared.

Don't forget that finite and finicky. A large download over a slow connection has a larger chance of being interrupted.

Everyone knows a interrupted update isn't good and downloading several times isn't good either.

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