The long awaited topic - LTE congestion

Azimuth

Azimuth

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And in pops sajunky. Kidding.

I've made some wild and stupid claims about LTE congestion due to UK LTE and a tangent I set myself upon. But I digress. After almost 1 year of my own personal LTE use and roughly 1 year that LTE is now live in SA, I've started to see what I *think* is congestion.

I'm happy to swallow my pride per line 1 para 2 and have this as a discussion topic.

Some wise words from a member over at S4GRU forums:

Speed is affected primarily by the size of the channel, the quality of the signal, and the number of people connected. The latter two are pretty simple, the more people on a tower the lower the speed will be and the worse your signal is the worse the speeds will be.

Channel size is the tricky one to understand. Spectrum is sold in blocks by the FCC (sic) in various sizes, like 5x5 and 10x10. A 5x5 is two 5 Mhz chunks of spectrum that are sold together. Sprint's current LTE pairs are as follows:
  • 800 Mhz: a single 5x5 or a single 3x3 (but we haven't seen the 3x3 yet)
  • 1900 Mhz: a single 5x5 in most areas, two 5x5s in a few areas (like Chicago)
  • 2600 Mhz: this spectrum works a bit differently, as it doesn't work in pairs. Sprint has, in most areas, at least 5 20 Mhz chunks, in some places they have more, in some places they have less.

The bigger the channel size, the higher the speed. A 5x5 goes up to 37.5Mbps, a 3x3 goes up to 22.5Mbps, and a single 20 Mhz chunk of 2600 will do about 85Mbps max.

This means that, theoretically, 1900 and 800 should have equal speeds in most places because both are 5x5s. But in real world scenarios, physics do not allow for it. As you probably know, 800 stretches further than 1900. This means that 800 is able to reach more people than 1900. It also can not be on every tower, as interference would cause issues. This means that generally, more people will be on an 800 channel than on a 1900 channel. So 800 will usually be slower. And 1900 will usually be faster because, going back to Robert's answer, there are more towers per square mile broadcasting 1900 than 800.

To use another carrier for an example, Verizon has a 10x10 on 700 Mhz. Because the channel size is 10x10, the max speed is 75Mbps, much faster than Sprint's 37.5Mbps 1900. But, 700 covers more people per tower than 1900, which means that 700 can get overloaded very quickly if too many people are connected. 1900 partially avoids this issue because less people are connected to any given tower.

So, in conclusion, the speeds are affected by channel size and how many people are on a channel or tower, not by the frequency number. However, the frequency indirectly affects speed, since higher frequencies require more towers to cover an area.
Click to expand...

I've left in what seems like irrelevant US content but there is a point...800MHz and 2600MHz. Also note we don't use 1900MHz here, it seems to be the equivalent of our 1800MHz.
 
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For the past year, I've been mostly on Telkom Mobile but more recently MTN.

TM issues started a couple months ago. My usual 50Mbps got bogged down to 10Mbps on what seemed like a perma basis. So I switched to MTN (Afrihost Mobile).

I can clearly see between 7pm and 11pm that download speeds slow to a crawl. The usual 30Mbps speed goes as low as 2Mbps. Upload remains high at 19Mbps.

Outside of peak time, I get 30Mbps all round. I seem to have at least 10 LTE users in my area now.
 
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Azimuth said:
For the past year, I've been mostly on Telkom Mobile but more recently MTN.

TM issues started a couple months ago. My usual 50Mbps got bogged down to 10Mbps on what seemed like a perma basis. So I switched to MTN (Afrihost Mobile).

I can clearly see between 7pm and 11pm that download speeds slow to a crawl. The usual 30Mbps speed goes as low as 2Mbps. Upload remains high at 19Mbps.

Outside of peak time, I get 30Mbps all round. I seem to have at least 10 LTE users in my area now.
Click to expand...

Yeah, that does happen,
I seen that happen with those HSDPA modems CellC came out with like 3/4 Years ago.

MTN just enabled LTE for prepaid customers the other day,
So there definitely should be more traffic on MTN network.
 
My MTN LTE was already bad because I'm far from the Antenna. I have been getting two bars and speed have been 2Mb at best. The introduction of prepaid guys will kill me.
 
Ouch, 5:30pm and already nose-diving.

931160338.png


Roughly same time yesterday:

930247238.png


I've reported this to Afrihost (who will in turn report to MTN) in the off chance something is screwy with the base station.
 
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The absolute best speed, assuming I'm the only person using LTE at 5:30am in the morning, is this:

931664703.png
 
Typical for our FDD-LTE by MTN. Vodacom doesn't have these speeds in all my testing. Note that upload never seems to be affected by congestion.
 
I'm not sure I can give a good explanation. I reckon that with normal internet use, it's something like 90% download and 10% upload. Perhaps one person at a time might do a large upload but the chances of all users doing this at the same time are virtually zero. As a result upload capacity always looks good.
 
Teejaybee said:
Yes I saw that.....why would that be....I would have thought both download and upload would be affected?
Click to expand...
Correct for TDD technology (Telkom Mobile) - it works as you say.

Not true for LTE FDD or 3G WCDMA technology. Higher upload speeds indicate clearly congestion. It is because upload channels are under utilized.
 
I've finally managed to profile the LTE installation I did here.

454527e3e43b253dcb508734acbbb436.jpg


Note that the test data ranges between 09 August - 20 August. Congestion may show up differently on a specific day if one were to plot throughout the day e.g. Sundays.

Congestion on this cell seems to occur between 9-11am, 12-2pm, 4-7pm and somewhere between 9pm and midnight (insufficient data).

I suspect that the backhaul definitely needs an upgrade or additional capacity added for LTE in the form of a separate microwave link. LTE and 3G sharing the same backhaul...doesn't paint a pretty picture. Even better would be a 100Mbps upgrade.
 
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I'll post mine in due course. I have a lot more data and 2013 vs 2014 results to compare.
 
I am on MTN (Afrihost) and every night after 6pm to about 11pm everything slows down to a crawl. The speedtest I did last night was 0.02mbs... while having full signal. I will probably have to cancel this and get something else as this has been going on since 1 July.
 
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