How much bandwidth does a single LTE site have?

[imekul]

This is something I've wondered for a while now...

 

How much bandwidth does a single LTE site/tower have? Say I'm in Atlanta and downloading a large file at 20 Mbps. How many people like me would it take to max out the bandwidth at that location at a given time?

 

Also, I want to make sure my understanding is correct about how LTE connections work. Say a tower gives off 100 Mbps. If I am the only one connected to it, I obviously won't get the full 100 Mbps, but perhaps would get 20-ish or whatever the maximum number that Sprint usually allows. If it's 20, then I imagine four other people connecting at the same time would all get 20 as well, and then if the total number of users jumped to 10, we would all get slower speeds (approximately 10 Mbps) to share the available bandwidth. With 20 users, we would each get approximately 5 Mbps. Is this generally correct?

 

By the way, I realize that it's not a real-world example, but when I say "users," I'm meaning people who are essentially maxing out their connection -- all doing speed tests, large file downloads, etc. People with a sustained large transfer.

[WiWavelength]

How much bandwidth does a single LTE site/tower have? Say I'm in Atlanta and downloading a large file at 20 Mbps. How many people like me would it take to max out the bandwidth at that location at a given time?

 

Most sites have three sectors. In Sprint's initial LTE deployment, each sector has a peak data capacity of effectively 37 Mbps, but average data capacity is likely closer to 20 Mbps. So, for you to download a large file and average 20 Mbps, you would probably have to be one of very few users on that sector at that time.

 

AJ

[miguell2]

Most sites have three sectors. In Sprint's initial LTE deployment, each sector has a peak data capacity of effectively 37 Mbps, but average data capacity is likely closer to 20 Mbps. So, for you to download a large file and average 20 Mbps, you would probably have to be one of very few users on that sector at that time.

 

AJ

 

So a sector physically is an area, say sector 1 would be from 0 degrees to 96 degrees and sector too from 97 degrees to 270 and so forth?

[imekul]

Most sites have three sectors. In Sprint's initial LTE deployment, each sector has a peak data capacity of effectively 37 Mbps, but average data capacity is likely closer to 20 Mbps. So, for you to download a large file and average 20 Mbps, you would probably have to be one of very few users on that sector at that time.

 

AJ

So when a site is complete, what would its capacity be? Are we talking three sectors times 37 Mbps, so essentially 110 Mbps per tower?

[WiWavelength]

So a sector physically is an area, say sector 1 would be from 0 degrees to 96 degrees and sector too from 97 degrees to 270 and so forth?

 

In a typical site configuration, the lowest numbered sector covers 300-60 degrees, the second sector 60-180 degrees, the third sector 180-300 degrees. All of the above reference N to 0 degrees and reflect a clockwise rotation.

 

AJ

[WiWavelength]

So when a site is complete, what would its capacity be? Are we talking three sectors times 37 Mbps, so essentially 110 Mbps per tower?

 

My question: why would you be concerned about the total capacity of the site? With LTE, no user can connect to more than one sector at a time.

 

AJ

[imekul]

Oh, just curiosity. If one tower covers an entire neighborhood or something, I'm wondering how much bandwidth all the users are sharing.

 

For that matter, do you happen to know the capacity of a 3G tower?

 

Thanks for the info!

[lilotimz]

iirc, sprint nv upgraded towers typically have microwave or fiber backhaul that has a capacity of 300mbps that can be increased if needed. Old legacy towers are typically supplied by T1 lines which has a capacity of 1.5 mbps each. Usually they bundle 3 of them together.

[WiWavelength]

For that matter, do you happen to know the capacity of a 3G tower? Thanks for the info!

 

Per sector·carrier, EV-DO Rev A has a peak throughput of 3.1 Mbps, but average aggregate throughput is likely closer to 2 Mbps.

 

AJ

[Den9696]

You def have a max at around 35mbs but I'm hoping that the site atleast have 1gb internet for a backhaul.

[miguell2]

You def have a max at around 35mbs but I'm hoping that the site atleast have 1gb internet for a backhaul.

 

What does it matter if the backhaul is so fast? You would be limited by the LTE connection so the rest would just be wasted.

[Den9696]

when you have thousands of people connected to one tower. You would hope that the back haul is fast so that it could handle multiple connections. Could be a major reason why sprints 3g network is soo bogged down right now in some areas.

[Boosted20V]

when you have thousands of people connected to one tower. You would hope that the back haul is fast so that it could handle multiple connections. Could be a major reason why sprints 3g network is soo bogged down right now in some areas.

 

If the backhaul is faster than the theoretical airlink connection, it is wasted speed. Now if Sprint acquires additional spectrum or hosts Clear's spectrum I understand that can change, but for the most part, having 1gb/s backhaul when your airlink can only support 300mb/s is a waste.

[imekul]

Great info, guys. Thanks for sharing! Interesting stuff.

[lilotimz]

when you have thousands of people connected to one tower. You would hope that the back haul is fast so that it could handle multiple connections. Could be a major reason why sprints 3g network is soo bogged down right now in some areas.

 

it is the reason that the network is so bogged down. Sprints original plan was for wimax phones to be on clearwires network and so didn't plan for the fact that Wimax expansion would stop and all the wimax phones will be using the legacy network and the T1 backhaul.

[CriticalityEvent]

Ok, apologies in advance for this barrage of questions, but I was trying to tie it all together here and needed a couple of things cleared up.

 

If the backhaul is faster than the theoretical airlink connection, it is wasted speed. Now if Sprint acquires additional spectrum or hosts Clear's spectrum I understand that can change, but for the most part, having 1gb/s backhaul when your airlink can only support 300mb/s is a waste.

 

Is the “theoretical airlink connection” that you’re referring to the maximum speed per sector? I would like to tie this into imekul’s question:

 

So when a site is complete, what would its capacity be? Are we talking three sectors times 37 Mbps, so essentially 110 Mbps per tower?

 

If each tower does have a total of 110 Mbps shared among three sectors, then would the backhaul only need to support a maximum of 110 Mbps? If this is the case, does it invalidate lilotimz’s comment about towers having a capacity of 300 Mbps?

 

iirc, sprint nv upgraded towers typically have microwave or fiber backhaul that has a capacity of 300mbps that can be increased if needed. Old legacy towers are typically supplied by T1 lines which has a capacity of 1.5 mbps each. Usually they bundle 3 of them together.

 

Does this mean that each legacy tower had a total backhaul capacity of 4.5 Mbps? If that’s the case, then per AJ’s comment…

 

Per sector·carrier, EV-DO Rev A has a peak throughput of 3.1 Mbps, but average aggregate throughput is likely closer to 2 Mbps.

 

AJ

 

…is it theoretically possible to use over half of a legacy tower’s capacity from a single sector?

[WiWavelength]

when you have thousands of people connected to one tower. You would hope that the back haul is fast so that it could handle multiple connections.

 

The "thousands of people" comment is misleading. Whether one user is connected to the sector or a thousand users are connected to the sector, the total downlink throughput for that LTE sector·carrier maxes out at 37 Mbps. The airlink is the bottleneck, not the backhaul, so 1 Gbps is definitely not necessary anytime soon.

 

AJ

[Boosted20V]

Ok, apologies in advance for this barrage of questions, but I was trying to tie it all together here and needed a couple of things cleared up.

 

 

 

Is the “theoretical airlink connection” that you’re referring to the maximum speed per sector? I would like to tie this into imekul’s question:

 

 

 

If each tower does have a total of 110 Mbps shared among three sectors, then would the backhaul only need to support a maximum of 110 Mbps? If this is the case, does it invalidate lilotimz’s comment about towers having a capacity of 300 Mbps?

 

 

 

Does this mean that each legacy tower had a total backhaul capacity of 4.5 Mbps? If that’s the case, then per AJ’s comment…

 

 

 

…is it theoretically possible to use over half of a legacy tower’s capacity from a single sector?

 

While the 5x5 1900mhz LTE carrier currently used offers 37.5mb/s per sector, remember you have 3G to support for EVDO and calls and you also will be adding another 5x5 carrier with 800mhz. So it's a function of the number of sectors (usually 3), but not every sector may be fully utilized. That still wouldn't need 1gb/s however. Regarding legacy backhaul, not ALL sites have 3 T1's, there are varying numbers, as well as some sites with AAV connections.

[billyjoejimbob]

Does this mean that each legacy tower had a total backhaul capacity of 4.5 Mbps? If that’s the case, then per AJ’s comment…

 

 

 

…is it theoretically possible to use over half of a legacy tower’s capacity from a single sector?

 

I believe that is theoretically accurate in the above scenario, which was a legacy site with 3 EVDO carriers (one per sector) and a total of 3 T1 lines for backhaul for all of them. I'm not sure if you can get the peak throughput 3.1mbps in the real world or not, but assuming you could, then yes in that scenario a sector running at maximum throughput would use 2 out of the 3 T1 lines for backhaul.

 

Sites have a varying amount of T1 lines for backhaul, but I believe that was the main problem with some of Sprint's sites getting so slow. They didn't have enough backhaul to support anywhere even close to 100% utilization of the sectors. At Sprint's Network site http://network.sprint.com you'll see towers listed as getting "Data Capacity Upgrades" and "Data Speed Upgrades". I could be wrong, but I believe the "Data Capacity Upgrade" refers to adding EVDO carriers, and the "Data Speed Upgrades" refers to adding additional T1 backhaul. Which is why you'll see many sites where the only upgrade is a "Data Speed Upgrade". They simply added more T1 backhaul to support the already existing EVDO carriers.

 

On the bright side of upgrades, Sprint finally got around to upgrading a site nearby which was mostly unusable for data regardless of the time of day or night. 4 Total upgrades. "1 voice upgrade, 1 data capacity upgrade, 2 data speed upgrades".

Edited November 29, 2012 by billyjoejimbob

[pyroscott]

Just to add this into the discussion, Sprint's backhaul contracts specified "scalable" backhaul. For comparison, Charter offers cable internet in my area, so they offer a basic 5mbps download speed, then you can scale up your connection all the way to 100mbps download speeds. This is what Sprint specified, so that when they add 800mhz LTE, additional 1900 mhz LTE carriers, clearwire LTE hotspots, microwave airlinks to other cell sites et cetera, they contact the provider and it gets bumped up. No waiting months for additional T1 lines to be delivered as before...

[DaQue]

5mbps? They only offer 30mbps and 100mbps here.

[PythonFanPA]

Most sites have three sectors. In Sprint's initial LTE deployment, each sector has a peak data capacity of effectively 37 Mbps, but average data capacity is likely closer to 20 Mbps. So, for you to download a large file and average 20 Mbps, you would probably have to be one of very few users on that sector at that time.

 

AJ

 

Not to change the subject, but it strikes me how this also helps illustrate/underscore the importance of Wi-fi offloading when available, particularly in the face of more egregious/abusive usage. Unless I'm misunderstanding the numbers here (and please by all means correct me if I am), say hypothetically you get more than say 10 max people downloading things over an extended period of time on one sector....and suddenly you're in danger of being back at square one in spite of Network Vision.

[Boosted20V]

Not to change the subject, but it strikes me how this also helps illustrate/underscore the importance of Wi-fi offloading when available, particularly in the face of more egregious/abusive usage. Unless I'm misunderstanding the numbers here (and please by all means correct me if I am), say hypothetically you get more than say 10 max people downloading things over an extended period of time on one sector....and suddenly you're in danger of being back at square one in spite of Network Vision.

 

Correct, which is why over time I don't see how you don't impose usage caps. Albeit higher than what ATT/VZ offer. Unless users are forced to keep in mind some semblance of usage, they waste the bandwidth. I suppose if you put Clear's holdings to full use it would put it off for a while but on a long enough timeline I still think caps are necessary.

[Sgt. Slaughter]

iirc, sprint nv upgraded towers typically have microwave or fiber backhaul that has a capacity of 300mbps that can be increased if needed. Old legacy towers are typically supplied by T1 lines which has a capacity of 1.5 mbps each. Usually they bundle 3 of them together.

 

 

Where are you getting this fiber capacity of 300Mbps figure from?

 

Fiber is theoretically unlimited...

 

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[Sgt. Slaughter]

Just to add this into the discussion, Sprint's backhaul contracts specified "scalable" backhaul. For comparison, Charter offers cable internet in my area, so they offer a basic 5mbps download speed, then you can scale up your connection all the way to 100mbps download speeds. This is what Sprint specified, so that when they add 800mhz LTE, additional 1900 mhz LTE carriers, clearwire LTE hotspots, microwave airlinks to other cell sites et cetera, they contact the provider and it gets bumped up. No waiting months for additional T1 lines to be delivered as before...

 

This right here!

 

Beauty of Fiber and not dealing with the limits of T1 junk... Much easier to up your limits... lot less excuses they can give for troubles once this is rolling and all.

 

Gonna be great!

 

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