Help Strange problem with HSPA+ mobile data speed!

[Tmansdc]

For the last three weeks I've noticed that my speeds while on HSPA+ 42 have been really wonky. It's like for a few seconds it'll go really fast, than slow down to EDGE/UMTS speeds for a few seconds than back up! It doesn't matter what time of day it happens to be. Same result. I did a very minor two foot drop onto bathroom linoleum three weeks ago but could that affect the download speed that way? Upload and latency/ping is just fine. EDGE also is fine. I'm just wondering what I should do? What could have happened? Like it'll go at about 4 to 12 Mbps than drop to about 200 to 400 kbps! Any suggestions/ideas?

Rom: Vanir Nightly 9/28/13
Baseband: .54
Kernel: Stock Vanir Kernel
Location: Boise, Idaho.

 

[Sasuke082594]

This also happens to me. My phone is a few days old and I think it has to do with android 4.3.

 

[jlg19753]

Mine also done the same. I changed a couple of APN settings and back to normal.

 

[Medion]

It's due to T-Mobile refarming. I'll explain better when I get home in front of my computer.

 

[Sasuke082594]

Mine also done the same. I changed a couple of APN settings and back to normal.

Can you share what you changed?

 

[Sasuke082594]

It's due to T-Mobile refarming. I'll explain better when I get home in front of my computer.

Awesome. Explanations are always good

 

[Medion]

It's due to T-Mobile refarming. I'll explain better when I get home in front of my computer.

Alright, here goes.

Think of the radio waves as a highway, and your data as the traffic on that highway. There's only so much that can be there at a time before congestion occurs.

Before T-Mobile started their refarm, their wireless spectrum allocation looked like this (think of each as a two-lane highway):

• GPRS/Edge - 1900mhz (PCS band)
• 3G/DC-HSDPA 42mbps - 1700/2100mhz (AWS band)

However, T-Mobile is currently working towards a goal that looks like this;

• HSPA+ 21mbps - 1900mhz (PCS band)
• LTE - 1700/2100mhz (AWS band)

You'll notice that DC-HSDPA 42mbps is gone. It's replaced by LTE, while GPRS/Edge gets replaced by HSPA+, 3G+ or 4G depending on how you feel about that. But, this would wreak havoc with all of T-Mobile's legacy phones. So, what we have going on right now (on refarmed towers), looks more like this:

• GPRS/Edge - 1900mhz (PCS band)
• HSPA+ 21mbps - 1900mhz (PCS band)
• 3G/DC-HSDPA 42mbps - 1700/2100mhz (AWS band)
• LTE - 1700/2100mhz (AWS band)

So once again, think of it as a 4-lane highway, only now it's one lane per allocation. LTE is data-only at this point, so it's not affected by voice. If you have an LTE signal, you're likely to get decent bandwidth. But the other three are capable of doing voice and data (some at the same time). But, voice gets priority. So if you're in a congested area, you'll see that your 3G/"4G" might have full bars, but data usage will pretty much suck. A good way to test this is to force your phone to 2G/Edge only. You'll suddenly get consistent (but slow) data.

This is further complicated by the fact that T-Mobile-branded handsets favor AWS over PCS for 3G/H+ usage, even if there's more available bandwidth on the PCS band. So until T-Mobile shutters their legacy networks, this will be an issue.

The best cure is to move to an LTE-enabled phone. Since the upgrade for me, it's been a world of difference.

 

[Sasuke082594]

Alright, here goes.

Think of the radio waves as a highway, and your data as the traffic on that highway. There's only so much that can be there at a time before congestion occurs.

Before T-Mobile started their refarm, their wireless spectrum allocation looked like this (think of each as a two-lane highway):

• GPRS/Edge - 1900mhz (PCS band)
• 3G/DC-HSDPA 42mbps - 1700/2100mhz (AWS band)

However, T-Mobile is currently working towards a goal that looks like this;

• HSPA+ 21mbps - 1900mhz (PCS band)
• LTE - 1700/2100mhz (AWS band)

You'll notice that DC-HSDPA 42mbps is gone. It's replaced by LTE, while GPRS/Edge gets replaced by HSPA+, 3G+ or 4G depending on how you feel about that. But, this would wreak havoc with all of T-Mobile's legacy phones. So, what we have going on right now (on refarmed towers), looks more like this:

• GPRS/Edge - 1900mhz (PCS band)
• HSPA+ 21mbps - 1900mhz (PCS band)
• 3G/DC-HSDPA 42mbps - 1700/2100mhz (AWS band)
• LTE - 1700/2100mhz (AWS band)

So once again, think of it as a 4-lane highway, only now it's one lane per allocation. LTE is data-only at this point, so it's not affected by voice. If you have an LTE signal, you're likely to get decent bandwidth. But the other three are capable of doing voice and data (some at the same time). But, voice gets priority. So if you're in a congested area, you'll see that your 3G/"4G" might have full bars, but data usage will pretty much suck. A good way to test this is to force your phone to 2G/Edge only. You'll suddenly get consistent (but slow) data.

This is further complicated by the fact that T-Mobile-branded handsets favor AWS over PCS for 3G/H+ usage, even if there's more available bandwidth on the PCS band. So until T-Mobile shutters their legacy networks, this will be an issue.

The best cure is to move to an LTE-enabled phone. Since the upgrade for me, it's been a world of difference.

I understand this. So now there is twice the traffic on two bands? Also moving to LTE depends on whether its covered in one's area. I enabled LTE on my Nexus 4 and left it on LTE only and no go.

 

[Medion]

I understand this. So now there is twice the traffic on two bands? Also moving to LTE depends on whether its covered in one's area. I enabled LTE on my Nexus 4 and left it on LTE only and no go.

The traffic is spread out, but due to the number of phones in peoples possession, the Edge and LTE "lanes" are wide open with minimal traffic, while the 3G/H+ "lanes" are heavily congested.

And yes, you're correct that towers have to have LTE enabled in order for LTE to work on your phone. I never disputed that.

 

[Sasuke082594]

The traffic is spread out, but due to the number of phones in peoples possession, the Edge and LTE "lanes" are wide open with minimal traffic, while the 3G/H+ "lanes" are heavily congested.

And yes, you're correct that towers have to have LTE enabled in order for LTE to work on your phone. I never disputed that.

I understand and sorry that is just something I wanted to point out

 

[Sasuke082594]

I got LTE working now BTW

 

[Tmansdc]

For the last three weeks I've noticed that my speeds while on HSPA+ 42 have been really wonky. It's like for a few seconds it'll go really fast, than slow down to EDGE/UMTS speeds for a few seconds than back up! It doesn't matter what time of day it happens to be. Same result. I did a very minor two foot drop onto bathroom linoleum three weeks ago but could that affect the download speed that way? Upload and latency/ping is just fine. EDGE also is fine. I'm just wondering what I should do? What could have happened? Like it'll go at about 4 to 12 Mbps than drop to about 200 to 400 kbps! Any suggestions/ideas?

Rom: Vanir Nightly 9/28/13
Baseband: .54
Kernel: Stock Vanir Kernel
Location: Boise, Idaho.

Well apparently there's nothing wrong with the towers here. At least that's what one of the head t mobile tech support told me. So apparently it's my phone but that seems fishy to me. What do you guys think?

 

[Medion]

Well apparently there's nothing wrong with the towers here. At least that's what one of the head t mobile tech support told me. So apparently it's my phone but that seems fishy to me. What do you guys think?

Your answer is in post #7.

The towers are work "correctly", not that a T-Mobile tech will tell you differently. But due to the refarm, bandwidth will be limited until the refarm is complete. Once the refarm in your area is complete, more people moving to LTE phones will help with your phone's performance.

 

[aurora40]

You'll notice that DC-HSDPA 42mbps is gone.

Good post, but where did that piece of information come from? Why wouldn't they still use DC-HSPA once they move it to PCS?

 

[Medion]

Good post, but where did that piece of information come from? Why wouldn't they still use DC-HSPA once they move it to PCS?

DC stands for dual-carrier. It needs two bands to work. 1900mhz is one band. That's why T-Mobile used it on AWS (1700/2100), and that's why AT&T doesn't have it.

Yes, you technically can use it on one band, so long as it gets two large chunks of bandwidth within that band, at least 2x10. No carrier has 20mhz of bandwidth across their entire network within one band. Even Verizon is limited to 5-10 mhz in some areas.

21mbps as their lower, fallback network is more than fine.

 

[Tmansdc]

It can't take two months to refarm can it?

 

[Medion]

It can't take two months to refarm can it?

T-Mobile has been refarming for more than a year. And once a tower has been refarmed doesn't mean that LTE will be ready to go right away. They have numerous towers around my house that have long since been refarmed but still don't have LTE turned on.

This is a slow process and will extend deep into 2015. By the time there are enough people on LTE phones to reduce the congestion for your phone, you'll be on an LTE phone yourself

 

[Tmansdc]

But even prior to two months ago?

I still think it's a hardware/phone issue.

Regardless I can hack and get LTE when it becomes available here.

 

[Medion]

But even prior to two months ago?

I still think it's a hardware/phone issue.

Regardless I can hack and get LTE when it becomes available here.

Yes, prior to two months ago. I stated for more that a year, but who knows specifically when your area was hit. It happens on my S4 and my wife's iPhone as well.

It's likely not a hardware issue. Your issue has been explained in this thread repeatedly. I won't waste anymore of your time or mine.

 

[Tmansdc]

No I know I just like making sure that's all. Thank you for all the info and help!

 

[aurora40]

DC stands for dual-carrier. It needs two bands to work. 1900mhz is one band. That's why T-Mobile used it on AWS (1700/2100), and that's why AT&T doesn't have it.

Yes, you technically can use it on one band, so long as it gets two large chunks of bandwidth within that band, at least 2x10. No carrier has 20mhz of bandwidth across their entire network within one band. Even Verizon is limited to 5-10 mhz in some areas.

T-Mobile only uses 1700 for HSDPA, though, 2100 is for uploads. DC-HSDPA doesn't require/work across both.

I'm of the impression AT&T doesn't have it because they invested in building out LTE instead, not because their spectrum can't support DC-HSPA (i.e. their equipment doesn't support it)?

I was also under the impression DC-HSDPA only needs 10MHz of spectrum, not 20. But I suppose we'll see if it goes away or not once T-Mobile is finished. I was wondering if you'd seen some release or info that specifically said T-Mobile wouldn't support it post-refarm.

 

[Medion]

T-Mobile only uses 1700 for HSDPA, though, 2100 is for uploads. DC-HSDPA doesn't require/work across both.

Correct idea, but you got it backwards. The FCC has authorized the 2110-2155 range for downlink, and the 1710-1755 range for uplink. [Source 1]

However, DC-HSDPA, while not requiring two entirely separate bands, does require two separate allocations of bandwidth in order to function. T-Mobile chose to use AWS for this, but they COULD do it within one band, such as 1900mhz (PCS). However, common deployments require a pair of 10mhz swaths (IE, 20mhz total, and split). To do any less would cause bandwidth starvation in highly populated areas. But yes, due to load balancing, DC-HSDPA under T-Mobile's current implementation does require both aspects of the AWS spectrum. [Source 2]

I'm of the impression AT&T doesn't have it because they invested in building out LTE instead, not because their spectrum can't support DC-HSPA (i.e. their equipment doesn't support it)?

I have no source for this, so take it as pure speculation. First, as sourced before, DC-HSDPA requires twice the spectrum as HSPA+ to reach a similar number of users. T-Mobile had tons of AWS spectrum holdings, and no LTE rollout plans at the time that Sprint rolled out WiMax. AT&T was preparing an LTE rollout in the 700mhz band. There was no need for AT&T to stretch their already taxed HSPA+ network into supporting DC-HSDPA. T-Mobile, however, had the spectrum to do it, and the smaller user-base to not be congested on it.

Given that AWS makes DC-HSDPA easier (separate large pairings of bandwidth), T-mobile has a huge leg-up in this area when compared to other carriers. [Source 3]

I was also under the impression DC-HSDPA only needs 10MHz of spectrum, not 20.

It requires paired, not continuous spectrum. It can be in a 5x5mhz pair (as T-Mobile is doing in refarmed areas), but 10x10 or 15x15 is optimal [See Source 2]. T-Mobile, thanks to the acquisition of MetroPCS, will be deploying 20x20mhz LTE in the AWS spectrum [Source 4], but to do so with DC-HSDPA today would be pointless.

But I suppose we'll see if it goes away or not once T-Mobile is finished.

T-Mobile has stated that they are not deploying DC-HSDPA 42 on the 1900mhz (PCS) spectrum. [Source 5][Source 6]

However, to clarify, T-Mobile has not set a shutdown date for their legacy networks. Smaller allocations of bandwidth will remain for Edge (PCS) and DC-HSDPA 42 (AWS) for the foreseeable future. Both Verizon and AT&T have set a deadline for their network shutdowns, but T-Mobile has not. As of right now, the current plan is for T-Mobile to utilize 75% of PCS for HSPA+ 21, and 75% of AWS holdings for LTE. They will use 25% of the legacy networks for legacy devices. [Source 7]

Here's a good graphic showing their intent. Please note that the "final state" is based on T-Mobile's current announcements. At some undisclosed point, they will shutter the old networks and allocate 100% PCS to HSPA+ 21 and 100% AWS to LTE.

I was wondering if you'd seen some release or info that specifically said T-Mobile wouldn't support it post-refarm.

I wanted to provide sources to back up my claims. You were right to not take me at my word, because, hey, this is a forum. If it's on the internet, it must be true, right? So out of respect for you, I wanted to provide sources to back up my claims, and then provide clarification. So, here's the clarification.

T-Mobile's goal was to refarm, enable LTE, then refarm some more. Previously, their 190mhz (PCS) network was Edge only. It's now on its way to 25% Edge and 75% HSPA+ 21. AWS was previously DC-HSDPA 42. It's now on its way to 25% DC-HSDPA 42 and 75% LTE.

If you have an LTE phone, you'll default to LTE on AWS, and HSPA+ 21 on PCS, once the current refarm and LTE rollout is complete. For phones with this hardware, there is no need for AWS DC-HSDPA 42, and your phone will almost never use it. So to finalize my clarification, the network will still be there for the foreseeable future, but newer phones will gravitate towards the newer network. I hope that I've done a better job of explaining my point of view.

 

[Tmansdc]

Well apparently they aren't refarming or doing anything LTE wise here yet. Darn it.


In any case I'll just wait until LTE comes to Boise or try it when I go to Vegas for all December. If it's still doing the same I'll take it in.

 

[aurora40]

I wanted to provide sources to back up my claims. You were right to not take me at my word, because, hey, this is a forum. If it's on the internet, it must be true, right? So out of respect for you, I wanted to provide sources to back up my claims, and then provide clarification. So, here's the clarification.

Awesome, thanks for the very detailed post! And for not taking offense. :beer:

 

[bjacks12]

LTE just came alive here. I'm tempted to ditch Straight Talk for T-mo.