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LU/Elizabeth Line 4G update
- Thread starter mrmartin
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RailUK Forums
JonnyM
Member
Indeed, but the throttling (if it is that, although it looks like it) is extreme though! It's gone from one extreme to the other. It's utterly unusable in its current state. I'm not one for running various speed tests as I think ultimately they are waste of time (the results being a snapshot of that moment in time) but trying a Speedtest at TCR the other day even the app timed out trying to find a server. Not good. It's not just at TCR, several other less used stations along the Central and Northern lines as well. Roll on the 4G rollout.......
Gigabit
Member
I feel like they need to tweak the priority so in stations where there is 4G automatic connection is disabled.
Do you mean WiFi auto-connection in stations with 4G?
Gigabit
Member
Yes, I feel like if a station has decent reception the Wi-Fi should just not be turned on, or it should be a manual connection. What is the point in it?
For staff use apparently. I can see it being made private once the rollout of cellular is completed
That's simply not possible to do — it's up to the device to decide whether or not to connect, not the network itself.
LTE and NR do have little used features that allow the network to choose whether to hand over data to a SIM Auth WiFi network, but I don't think any network equipment vendor actually implements this, and I don't think any devices support it either. Even with this, the device, if the network is saved, would still connect automatically.
LTE and NR do have little used features that allow the network to choose whether to hand over data to a SIM Auth WiFi network, but I don't think any network equipment vendor actually implements this, and I don't think any devices support it either. Even with this, the device, if the network is saved, would still connect automatically.
Gigabit
Member
That's actually not correct, O2 with Wifi Extra automatically steer you to/from WiFi to 4G/5G depending on signal strength.
But for London Underground Wi-Fi, why not just disable it altogether at stations with good 4G and 5G coverage? Do we need station Wi-Fi anymore?
Does it steer away from Wi-Fi though? If I have a Wi-Fi network connected via SIM authentication then it would appear it will just connect and stay there - however bad the service might be. As such I choose to not set up O2 or BT Wi-Fi hotspots because more often than not, it will be a poor experience and I could just use a cellular connection. But, on the flip side, I then have to manually connect (and later forget) when there is no cellular connectivity.
I think you'd need to have no Wi-Fi connectivity at all for the phone to decide to try and fall back to cellular data, although I see some phones* claim to have a feature that will analyse the data and choose - but I'm not sure how well it works, if at all.
* This is a Chinese phone that is sold in India and Africa, and is one of the only devices I've seen with such an option - as well as one to swap the chosen SIM for data if one fails. I think every other phone I've used makes you manually choose SIM 1 or 2 for data, and it won't swap automatically (exception being if you make a call on one, but that's a separate setting).
Blindtraveler
Established Member
The Google pixel that I'm using has this feature and I can tell you that it works very very well.
Perfect example is at Woolwich Elizabeth line, the 5G penetrates down the escalators and a good halfway along the platform so if you are either standing on the platform or on board the train towards the front it works out that wifi extra is nowhere near as good as the 5G getting in from above and so reconnects to that instead.
Perfect example is at Woolwich Elizabeth line, the 5G penetrates down the escalators and a good halfway along the platform so if you are either standing on the platform or on board the train towards the front it works out that wifi extra is nowhere near as good as the 5G getting in from above and so reconnects to that instead.
They really don't. The only way they can do it is with the 3GPP spec for WiFi Offload (explanation here: https://www.sharetechnote.com/html/Handbook_LTE_WiFi_Offload.html) but they don't or devices would be connecting when they don't even have the network saved.
It's just the phone automatically choosing WiFi when it thinks it will provide better signal and switching back to mobile data at lower signal strength...
I believe most devices automatically add WiFi Extra when you insert an O2 SIM, which is how it often doesn't require any pre setup. I think iPhones do the same for EE-WiFi-Auto but I'm not sure.
Android + iOS support this for sure.
It's actually annoying on Android as it's not clever enough to figure out that even though the wifi signal isn't good, the 'full' 4G/5G it's seeing is horribly congested and actually worse.
iOS actually supports (and maybe Android does, not sure) multipath tcp which allows it to connect to servers (that support multipath TCP, which are fairly rare apart from Apple's core services) with both the cellular + wifi simultaneously. It's fairly flakey though as loads of things along the way need to not block it which is rare.
As MrJeeves has said, the decision to move is based on signal strength (RSSI?) and very primitive - with no analysis of what is the best connection to use*. My home mesh network allows me to set various parameters to encourage a device to move from one base to the other, but the device still chooses and often doesn't choose well (example; toggle flight mode on and off and then see it connect to a better AP - which it wouldn't do otherwise).
There are parameters for Wi-Fi Calling that will favour mobile over Wi-Fi or vice versa, but most networks now hide that option to the user. EE has a preferred setting it wants all users to have - for example - which is probably to make customer support easier than having the user able to tweak everything themselves.
* It's much the same with connecting to a specific band that might have a terrible throughput due to congestion, yet is favoured due to having the best signal. The sheer number of different devices, with different chipsets and modems, and different setups when it comes to carrier aggregation etc just muddies the water even more.
There are parameters for Wi-Fi Calling that will favour mobile over Wi-Fi or vice versa, but most networks now hide that option to the user. EE has a preferred setting it wants all users to have - for example - which is probably to make customer support easier than having the user able to tweak everything themselves.
* It's much the same with connecting to a specific band that might have a terrible throughput due to congestion, yet is favoured due to having the best signal. The sheer number of different devices, with different chipsets and modems, and different setups when it comes to carrier aggregation etc just muddies the water even more.
Probably RSRP to be even more rudimentary!
AFAIK, most Android devices use solely RSRP for signal bars too. Only exception is Sony devices which seem to use RSSI (or some custom RSRP + SINR combination).
O2 WiFi already does that, it detects the strongest signal and will either keep you on the cellular network or switch to their own public WiFi.
No, your phone decides what to use at any given moment. The same applies when you get to and leave your home's WiFi network range.
Wi-Fi is also very bad for someone who is moving, because the roaming aspect is so hit and miss (see earlier posts). I used to use (Virgin) Wi-Fi on the tube loads early on as I could attend an event, capture loads of photos and video, then upload on a platform at high-speed (and no use of my then limited mobile data allowance). But you needed to sit on one access point and not move around, where you'd likely cling on to the AP you first registered on but now with a terrible signal.
JonnyM
Member
Gigabit
Member
That's not correct, unless you don't believe O2's own website.
Something extra for O2 customers
If you have an O2 sim card and a compatible device then Wifi Extra will automatically connect you to one of our thousands of wifi hotspots where the signal is stronger than 3G or 4G in that area.
You don’t need to do anything. Just leave it to our smarter network; we’ll pick the right connection for you so you’re always getting the best experience.Of course, you can still choose to connect manually to O2 Wifi whenever you’re in one of our hotspots by manually selecting O2 Wifi in your device’s settings.
And it's not just for O2 customers, our guest wifi is free for everyone, no matter who your mobile or home broadband contract's with.
Are they ever going to turn on any more stations?
I believe O2's website no more than their coverage map: not one bit.
Gigabit
Member
That's fair enough but I did provide evidence for my statement so unless you can conclusively disprove what O2 have said I will stick with my original statement.
It judges by signal strength, so if WiFi is strong it will connect to it. And when Wi-Fi drops below a specific threshold, it swaps back. It can at times do this a lot, causing battery drain and pauses in service.
It does not analyse the quality of service or look at what will provide the best speed for the user (something that would be quite hard to do as performing speed tests would use data, take time and drain your battery).
So O2 is right in what it says, but it doesn't say what you think it does.
It does not analyse the quality of service or look at what will provide the best speed for the user (something that would be quite hard to do as performing speed tests would use data, take time and drain your battery).
So O2 is right in what it says, but it doesn't say what you think it does.
Gigabit
Member
August has basically been and gone and no more stations seem to have gone live 
The Wi-Fi on the District Line seems to have completely stopped working tonight, no data flow at all.
The Wi-Fi on the District Line seems to have completely stopped working tonight, no data flow at all.
JonnyM
Member
TCR is now live, on Vodafone at any rate. The 4G reception was terrible though, maybe a few tweaks need to be made. From a friend who was also passing through TCR, 5G reception was solid. Sadly, still not coverage in the tunnels. Once the train left TCR reception dropped off.August has basically been and gone and no more stations seem to have gone live
The Wi-Fi on the District Line seems to have completely stopped working tonight, no data flow at all.
JonnyM
Member
Do you know roughly when the tunnels are going live? Or is it more technically difficult? Don't get me wrong though, more stations that go live the better! Even more important now that wifi at stations is so rubbish.
I can't share anything at the moment
Regarding wifi vs 4G/5G - I think there'd still be value in offloading as many customers as possible to wifi, especially those who are on the platform or elsewhere and not moving around much. The cellular network is going to be quite busy if there's a rush on. That is, assuming the wifi continues to work once the mobile network goes in & assuming the MNOs continue to pay for access which they may choose not to do.
Same scenario as in an office or at home - you don't use the cellular network unless you really need to
Same scenario as in an office or at home - you don't use the cellular network unless you really need to
The point is that mobile networks are explicitly designed for high capacity use cases like this. They're very good at scheduling throughput for a large number of devices (this is broken down into small units called "resource blocks") and doing this fairly in order to provide peak speeds to high traffic users but also low latency to other users of the site who just need to load an email for a few hundred milliseconds.
Even Wi-Fi 7 isn't designed for the number of users that a cellular based network is.. and most people aren't using Wi-Fi 7, or even 6/6E. Factor in people using Wi-Fi 4 or 5 and it really isn't a great experience, except for people who intentionally want to use it and are definitely staying still. Roaming on Wi-Fi is a mess!
Underground Wi-Fi might be a little bit more manageable, but once you're in more open environments you will have all the congestion of other APs in use from local shops, offices, homes etc.
In an office or at home, you are in far more control (especially the latter).