T-Mobile "4G" / HSPA+

[anon62607]

When t-mobile says that they have HSPA+ and that it's a 21 mbit network, does that imply that it can support category 14 UE (i.e., 15 codes on 64QAM)? And if the G2 and MyTouch 4G are 14.4 mbit - does that imply that they're category 10 UE? (15 codes on 16QAM with a .97 code rate (14.0 mbps) giving a 14.4 mbps data rate?)

The reason I'm asking is that category 10 is a release 5 HSDPA spec - which would imply the phones are not actually even HSPA+, but rather "just" regular HSDPA but using 15 spreading codes.

Also I noticed while looking through qualcomm slides it notes that the MSM7230 has "HSPA+ features" - is that implying again that it's just HSDPA with 15 codes?

 

[sniffs]

Them calling their HSPA+ network "4G" is a play on consumer's and going to confuse the hell out of them.

I hope AT&T sues them for false advertising, consumer confusion(claiming they have the largest "4G"(HSPA+) network when that is simply not the case.. AT&T's is much bigger.

I know carriers are evil, but this is downright stupid on T-Mobile's part.

 

[anon62607]

I was more asking if the G2 and myTouch 4G are HSPA+ phones.

 

[sniffs]

Yes they are considering T-Mobile's "4G" network is HSPA+

 

[anon62607]

Not just the network but the phones themselves. As I said it appears that it's using a 3GPP revision 5 spec category which would be regular HSDPA, and it's getting it's 14 megabit download performance from using 15 spreading codes.

 

[sniffs]

I'm pretty sure it is because even phones on AT&T that are HSPA+ can access their normal 3.6Mbps connection and when/if AT&T releases 7.2Mbps, nothing needs to be done to the phone, it just recognizes the increased throughput.

 

[anon62607]

yes, in fact there are a large number of possible speeds that any given HSDPA phone can connect at. If 16QAM is available for example that implies that QPSK is available and so on. So that isn't ready my question.

3GPP released several revisions of the spec. Rel 5 is what we think of as HSDPA, rel 6 added what we think of as HSUPA, and then there is rel 7 which is what is known as HSPA+.

Heres the thing, there is a 14 mbps speed available on rel 5, using 16 QAM modulation and using 15 of the 16 available spreading codes.

My question is therefore is that what the G2 and myTouch 4G are using? Or are they using one of the rel 7 categories with a limited number of spreading codes?

 

[Kevin OQuinn]

Hmm...this might explain why my Optimus T will connect to the HSPA+ network. It's not supposed to but it does.

OP, what you're talking about is above my head as far as knowledge goes, but I would think that my (supposedly) non-HSPA+ phone connects to HSPA+.

I had to contact T-Mobile tech support about a separate issue and mentioned that I see the H on my phone and they were very confused and didn't understand how that's possible. You may be correct in assuming they are using some trickery here.

 

[anon62607]

Yes, it will connect to the HSPA+ network because HSPA+ is really just additional categories of HSDPA (3G) intended for higher speed.

To make things simple, think of HSDPA transmissions as occupying 2 milliseconds and in those 2 milliseconds data there are 16 "slots" available. How much data those slots hold depends on several factors including modulation and number of error correction bits vs. payload bits and so on, but ignore all that for the time.

A 3G network that can transmit at a maximum of 3.6 Mbps is using 5 of those 16 slots - the device receiving at 3.6 Mbps is listening on 5 of those 16 slots for data. If the network is limited to 3.6 mbps it will never transmit to one device on more than those 5 slots.

Now perhaps the network gets upgraded to support 7.2 Mbps 3G. Those networks transmit on up to 10 of those 16 slots. If a phone is able to listen on 10 slots (a category 8 device) then it can receive at 7.2 Mbps. If it can only listen on 5 slots it can still connect to the network, but it tells the network what is the maximum number of slots it can listen in on and the network won't send any more than that. So someone's 3.6 Mbps phone can connect to a faster 7.2 Mbps network, but that won't help the performance of the 3.6 Mbps phone - it's still stuck at 3.6 Mbps by it's own limitation.

Then there is HSPA+ - it can send on 15 of those 16 slots, and not only that it can use a higher order modulation (more data per slot) and also it can send fewer error correction bits per payload bit, which when added together allows for 21 Mbps. That is what T-mobile's network currently is. However, the myTouch 4G and the G2 only support some of that - they can listen on 15 slots and they can use modes that have fewer error bits per payload bit, but they can't use higher order modulation. All together this means that they can receive up to 14.4 Mbps (really 13.98 Mbps of actual data, the remainder are error correction bits).

Now, regular HSDPA (3G) phones can still connect to T-Mobile's HSPA+ network, but they inform the network that they are unable to receive on more than 5 or 10 slots (as the case may be) and that they have to use the worse error bit vs. payload bit modes, so they are still limited to 3.6 Mbps or 7.2 Mbps.

Those "slots" are really spreading codes - a signal is spread via CDMA across a wider spectrum at transmission and despread by the phone when it is received, but it's easier to just think of them as "slots".

So here's the deal, if you got what I said so far:
Revision 5 of the 3G spec includes the mode that allows for 14.4 Mbps transmission - 15 slots (spreading codes), 0.98 code rate and 16QAM modulation. That isn't HSPA+, it's regular HSDPA. T-Mobile's network is HSPA+, but the G2 and MT4G are connecting to it in a HSDPA kind of way.

 

[Kevin OQuinn]

Yes, it will connect to the HSPA+ network because HSPA+ is really just additional categories of HSDPA (3G) intended for higher speed.

To make things simple, think of HSDPA transmissions as occupying 2 milliseconds and in those 2 milliseconds data there are 16 "slots" available. How much data those slots hold depends on several factors including modulation and number of error correction bits vs. payload bits and so on, but ignore all that for the time.

A 3G network that can transmit at a maximum of 3.6 Mbps is using 5 of those 16 slots - the device receiving at 3.6 Mbps is listening on 5 of those 16 slots for data. If the network is limited to 3.6 mbps it will never transmit to one device on more than those 5 slots.

Now perhaps the network gets upgraded to support 7.2 Mbps 3G. Those networks transmit on up to 10 of those 16 slots. If a phone is able to listen on 10 slots (a category 8 device) then it can receive at 7.2 Mbps. If it can only listen on 5 slots it can still connect to the network, but it tells the network what is the maximum number of slots it can listen in on and the network won't send any more than that. So someone's 3.6 Mbps phone can connect to a faster 7.2 Mbps network, but that won't help the performance of the 3.6 Mbps phone - it's still stuck at 3.6 Mbps by it's own limitation.

Then there is HSPA+ - it can send on 15 of those 16 slots, and not only that it can use a higher order modulation (more data per slot) and also it can send fewer error correction bits per payload bit, which when added together allows for 21 Mbps. That is what T-mobile's network currently is. However, the myTouch 4G and the G2 only support some of that - they can listen on 15 slots and they can use modes that have fewer error bits per payload bit, but they can't use higher order modulation. All together this means that they can receive up to 14.4 Mbps (really 13.98 Mbps of actual data, the remainder are error correction bits).

Now, regular HSDPA (3G) phones can still connect to T-Mobile's HSPA+ network, but they inform the network that they are unable to receive on more than 5 or 10 slots (as the case may be) and that they have to use the worse error bit vs. payload bit modes, so they are still limited to 3.6 Mbps or 7.2 Mbps.

Those "slots" are really spreading codes - a signal is spread via CDMA across a wider spectrum at transmission and despread by the phone when it is received, but it's easier to just think of them as "slots".

So here's the deal, if you got what I said so far:
Revision 5 of the 3G spec includes the mode that allows for 14.4 Mbps transmission - 15 slots (spreading codes), 0.98 code rate and 16QAM modulation. That isn't HSPA+, it's regular HSDPA. T-Mobile's network is HSPA+, but the G2 and MT4G are connecting to it in a HSDPA kind of way.

Ahh that makes sense. What I wonder is if you have to have a certain level of connection for the phone to report a H by the signal strength.

Thanks for the explanation.

Sent from my Optimus T

 

[anon62607]

I think that tmobile phones always report an "H" on any HSPA connection no matter if it is release 5 or release 7 as it's nicely ambiguous.

My vibrant reports "3G" on the same connection that my myTouch 4G and G2 report "H" on. Come to think of it the galaxy tab also reports 3G. I guess I'm not sure about tmobile's reporting scheme.

 

[Kevin OQuinn]

I'm still thinking that the Optimus has a radio that can take advantage of some of the benefits of HSPA+. But obviously I can't confirm this.

 

[anon62607]

The modem is the MSM7627. I think it's a category 8 device but qualcomm's site is notoriously difficult to find information on and I dud see a couple of references that it may support category 10 modem which would be 14.4 mbps and could be considered HSPA+. I doubt that this is the case though.

Sent from my SGH-T849 using Tapatalk

 

[Kevin OQuinn]

Hmm...well I don't have the Optimus T anymore. I have the G2 now, which officially supports HSPA+. I get the H in all the same areas (if not more) than I did with the Optimus. Going into settings confirms that I'm connected to UMTS, not HSPA. I did some reading and found out that as far as the notification bar goes you can't tell which one you're on, you have to go into settings and check.

 

[anon62607]

I don't think the G2 will show anything other than G, E, and H. I've yet to see a 3G indicator on mine.

Sent from my SGH-T849 using Tapatalk

 

[Kevin OQuinn]

Yeah I haven't noticed anything other than those either. The same place I read for the above info also said that it only has those indicators built in. I would love a way to display HSPA+ in the notification bar.

 

[d3xn2o]

U could always Theme it and Fake the funk brotha

 

[TvTechGuru]

T-Mobile should be sued for false advertising and false claims. I've been seeing their TV commercials running all the time lately advertising "Largest 4G Network". What a bunch of crap. They don't even have a 4G network. Heck they're lucky if they can even say they have 3G. Everyone I know who has or had T-Mobile couldn't make a call to save their life.

 

[anon62607]

T-Mobile should be sued for false advertising and false claims. I've been seeing their TV commercials running all the time lately advertising "Largest 4G Network". What a bunch of crap. They don't even have a 4G network. Heck they're lucky if they can even say they have 3G. Everyone I know who has or had T-Mobile couldn't make a call to save their life.

I haven't been with tmobile long but I do frequently use them for calling now and never had a dropped or non connected call, in contrast to the way AT&T was for me.

Tmobile's hspa network is as much 4G as sprint's wimax or verizon's lte, and in contrast to those two, tmobile can carry voice and data over what they call 4G, for verizon and sprint the 4G portion is data only and there's no provision for carrying voice over evdo rev a (that they have implimented) so in all seriousness technically you could make the claim that verizon and sprint don't have a 3G network.

 

[INK]

T-Mobile should be sued for false advertising and false claims. I've been seeing their TV commercials running all the time lately advertising "Largest 4G Network". What a bunch of crap. They don't even have a 4G network. Heck they're lucky if they can even say they have 3G. Everyone I know who has or had T-Mobile couldn't make a call to save their life.

Actually none of the companies provide "True 4g". Though in terms of technology the closest to actual 4g is Long Term Evolution(LTE) which is a more advanced then HSPA+ though by how much is unknown. I think verizon's 4g lte might have the placebo effect right now . I hear great things about T-mobile's 4g, Wimax not so much. And the reason no one has true 4g is their networks aren't strong enough to be considered true 4g, but they were given the thumbs up to brand 4g to their networks for retailing. Blame the ITU lol.