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5G overview

sheytoon
Mayor / Maire

Hi everyone,

 

Although Public Mobile may not support 5G any time soon, I thought I would start writing about what's new with this latest technology. There's a lot of terminology and confusion, so hopefully this will help!

 

You may have heard the terms NSA, SA, NR, DSS, mmWave, network slicing, and many other buzzwords. But what does it all mean?

 

To start, let's get some definitions out of the way.

NR = New Radio, this is the 5G wireless standard (equivalent to LTE for 4G)

eNodeB (eNB) = 4G base station

gNodeB (gNB) = 5G base station

NSA = Non-standalone, a type of 5G connection requires 4G at the same time in order to operate

SA = Standalone, a type of 5G connection has no dependency on 4G

 

At a high level, there are 3 broad categories for 5G, and the technology is expected to support these use cases:

1) eMBB: enhanced mobile broadband
2) mMTC: massive machine-type communications
3) URLLC: ultra reliable low-latency communications

 

Let's talk about each in a bit more detail.


eMBB is what we're all using today. It's smartphones and other devices that support extremely high speeds and capacity for things like high speed data, fixed wireless broadband (wireless home internet), virtual or augmented reality (VR/AR). This is supported with 5G NSA and 5G SA.

mMTC will come later. It will support massive deployment of IoT devices, which basically means sensors and smart devices everywhere. Think millions of devices needing very little data. This will be supported only on 5G SA.

URLLC is also a future technology. Its goal is sub 1ms latency and extremely high reliability for mission-critical applications like factory automation, remote controlled vehicles, remote surgery, etc. It's important to note that URLLC can't support high Gbps throughput. This will be supported only on 5G SA.

 

Ok, let's talk about the differences between SA and NSA. Basically it comes down to 2 things. SA needs a new 5G core network, while NSA can use the old 4G EPC core network, but it must also use 4G eNB at the same time.

 

When 5G was first being developed as a concept, researchers came up with 7 different network options:

  1. eNB connected to EPC (4G core) --> this is the existing LTE network

  2. gNB connected to 5GC (5G core) --> this is the final stage of the 5G Standalone (SA) network

  3. NSA EN-DC: eNB and gNB connected to EPC (LTE is anchor)

  4. NSA NE-DC: eNB and gNB connected to 5GC (NR is anchor) --> not going to be deployed

  5. eNB connected to 5GC --> not going to be deployed

  6. gNB connected to EPC --> not going to be deployed

  7. NSA NGEN-DC: eNB and gNB connected to 5GC (LTE is anchor) --> not going to be deployed

 

Here is a visual representation of all the options, courtesy of GSMA:

GSMA 5G options.JPG

 

You can see 3 possibilities for NSA. Operators and vendors settled on Option 3x (a variant of Option 3) since it didn't require a new 5G core network. This allowed the industry to rapidly deploy 5G NSA while using existing 4G core networks.

 

You may have heard the term LTE anchor, or anchor band. In the context of 5G NSA, all of the signaling between the network and phone is done on LTE. In order for 5G NSA to work, the phone must first find a suitable LTE band to act as an "anchor", and then wait for the network to add 5G on top for extra speed. It also means if a 5G NSA phone only has 5G coverage (no LTE), it won't work. It'll be completely out of service. Finally, voice calls on 5G NSA are done entirely on LTE with VoLTE.

 

Only Option 2 and Option 3x are actually adopted and deployed by the industry for 5G.

 

The deployment of a brand new 5G Core for SA is extremely complex and requires considerable effort and resources. This is the main reason why 5G NSA was introduced.

 

With 5G NSA, there can be many bands on the LTE side and NR side. For example, an operator can deploy 32 CA LTE + 16 CA NR in principle, but they would need to have lots of spectrum, RAN software that supports it, and most importantly a phone that supports that specific combo in order to use it. Bell/Telus are currently deploying 2-7-7-66_n78_n78. They have 4 LTE + 2 NR bands aggregated as their main combo. They can add more combos on their network, but without a phone that can use those combos, it's pointless.


5G band numbers start with lower-case "n", to differentiate from LTE. For example, Telus can deploy LTE band 66, or NR band n66. It's the same spectrum. An operator can choose to deploy their spectrum as LTE or NR as they wish.

 

A new concept in 5G is DSS or Dynamic Spectrum Sharing. This allows an operator to deploy a frequency band as 4G and 5G simultaneously. The eNB and gNB will dynamically schedule traffic to users depending on the demand. There is quite a bit of overhead and inefficiency associated with DSS (especially on the 5G side), so it is not used for small channels like 5 or 10 MHz. Typically it is used for 15 or 20 MHz.

 

Let's talk about peak speeds (or eMBB). With a combo like 2-7-7-66_n78_n78, there is 75 MHz of LTE and 80 MHz of 5G (GTA spectrum). This can get close to 3 Gbps technically, but a realistic speed test would yield something like 1-2 Gbps in good conditions. If Bell and Telus launched SA, they would only have n78-n78. They can't use the LTE bands at the same time in an SA scenario. Which means, peak speeds on SA will be slower than NSA, at least for a few years until phone manufacturers stop supporting new NSA combos. Eventually NSA will stop being developed and everyone will work to make SA better. At some point in the next few years, we will see SA speeds catch up to NSA.

 

As for latency, there is a small improvement with 5G compared to LTE in general, even with 5G NSA. This can bring real-world latency down to low double digits, with the eventual promise of low latency coming with URLLC. This technology promises latencies of less than 1ms, but it will not be a simple achievement. There are going to be many years of small, incremental improvements until we see latencies in the low single digits.

 

From what I've seen so far, networks cannot support high throughput and sub-ms latency on the same device. The tradeoffs needed to achieve low latency will result in lower throughput. I believe smartphones will be designed for peak speeds, and may get to 5ms latency, but not sub-ms. New applications will require sub-ms latency on specialized 5G equipment, which will be achieved by trading throughput for better latency and reliability. URLLC is only possible with SA.

 

Another important concept that will be introduced with 5G SA is Network Slicing. This is the concept of the network giving specific resources and profiles to user applications, similar to what I described above with eMBB, mMTC and URLLC. Here's a good picture, again courtesy of GSMA:

GSMA slicing.JPG

 

Lastly, let's talk about spectrum. All existing LTE bands can be used for 5G. Some bands that are overlapping are no longer defined. For example, in LTE we have B17 and B12, where B12 is a superset. In 5G we only have n12. Same idea for B4 and B66, in 5G we only have n66.


Alright, so now we know operators can repurpose or "re-farm" their existing spectrum for 5G when they are ready. They can also use DSS to do a soft re-farm of 4G and 5G on wider channels like 15 or 20 MHz.

 

In the initial 5G specifications, 3GPP defined traditional frequencies as "Frequency Range 1", also known as FR1. This was spectrum up to 6000 MHz, which is why people started referring to it as sub-6 or sub 6 GHz. The specs were later modified and FR1 now goes up to 7125 MHz, although sub-6 is a term that is still used. A new frequency range known as FR2 has been adopted, operating in much higher frequencies.

 

FR2 frequencies have wavelengths generally less than 1cm. For this reason, FR2 is commonly referred to as millimeter wave or mmWave.

3GPP TS38.104.JPG

 

As always, if you have more questions, just ask and I will be happy to try to answer them!

Previous topics are still available here: https://productioncommunity.publicmobile.ca/t5/Get-Support/LTE-network-fundamentals/td-p/130581

38 REPLIES 38

darlicious
Mayor / Maire

You know you don't have to drink the purple koolaid?🍇

WoozyPolarBear
Model Citizen / Citoyen Modèle

Public Mobile will NEVER support 5G. Not ever! In fact, Public mobile is much more likely to regress and go back to analog service or at the very least PCS. This is the most backward tech brand in Canada you are talking about.

Kristowhy
Model Citizen / Citoyen Modèle

@sheytoon wrote:

Thanks for the feedback, I'm glad you found it useful!

 

Love this amazing info and answers to my questions - thanks!

 

It's time we all stand up and give @sheytoon a standing ovation! 🏅👏👏

Community_QA
Model Citizen / Citoyen Modèle

Thanks @sheytoon   for the great info

 

 

Thanks for the feedback, I'm glad you found it useful!

 

@Kristowhy wrote:

Since operators are currently doing NSA, are all "5G" marketed devices now (including the expensive flagships) NSA-only or do they support SA as well (hybrid)?  You mentioned the industry will move to SA in a few years and I wonder how this will transpire with devices.   Perhaps another device upgrade push for "5G gen2"?  Manufacturers are going to love that if that's the case!  


It depends on the phone's software. Samsung S21, S22, Google Pixel, iPhone 13 can all support SA and NSA. It's simply a matter of operators and phone manufacturers coming to an agreement to enable SA. The other requirement would be provisioning for the account/SIM to allow access to SA networks. There doesn't seem to be a rush to SA right now because there are no benefits to customers, and the 5G core is not mature. Operators are hesitant to risk user experience by putting customers on a brand new core that may not be stable.

 


You mentioned that all 5G voice calls are currently done using VoLTE.  How will this change once SA begins to be pushed out?  I assume this will move to "Vo5G"?  Will devices need to support NSA and SA concurrently for a seemless "transition"?

For this question, I'll copy and paste from one of my responses on reddit...

There's 3 stages of voice with 5G:

  1. 5G NSA is currently using regular VoLTE

  2. 5G SA will initially use EPS fallback (EPSFB) to switch to LTE for VoLTE, and the device will return to 5G SA after the call ends. Similar to how initial LTE networks used CS fallback (CSFB) to send voice calls to 3G.

  3. 5G SA will eventually use native VoNR when SA coverage is good and operators enable it

We are at stage 1 right now, but Rogers also has stage 2 on their newly launched SA network. Bell and Telus only have stage 1 since there's no SA on their networks.

 

Don't know when stage 3 will come. It could be later this year for Rogers, but my suspicion is next year.

Devices will need to support SA and LTE for a seamless transition. 5G NSA is totally optional because NSA doesn't have any signaling with the 5G base station or core network. All signaling is handled with the LTE base station and 4G core network.

 


Many have heard about the lower battery life of devices using 5G.  Is this a direct result of having to use NSA with what appears to be a lot of switching between different mechanisms?


I haven't noticed much of a battery drain myself, but yes, having 2 transmitters active for 5G NSA (4G + 5G) at the same time would use more energy, so it makes sense.

 


And finally, you mentioned that all existing 4G LTE bands can be used for 5G.  Correct me if I am wrong, but it would seem like the 3G UMTS/HSPA network (and the spectrum it is using) is a hurdle to faster 5G NSA deployments.  Could this spectrum currently being used by 3G network be leveraged here?  Isn't this why the US carriers have decommissioned their 3G networks?

For the Big 3 operators, there's not a lot of spectrum remaining on 3G networks. Bell and Telus have 5 MHz of Band 5 (850) and 5 or 10 MHz of Band 2 (1900) in most markets. I don't think it would make much of a difference to move those bands to 5G right now. It's especially difficult to do when there are so many customers (like PM) that rely on 3G for voice calls still. First thing operators need to do is enable VoLTE for all. Then they can decommission 3G.

 

US operators re-farmed 3G spectrum earlier because they had more congested LTE networks than Canada, and no B7 to provide additional LTE capacity. Our LTE networks in Canada are holding up well, and there isn't as much of a need to aggressively re-farm 3G spectrum.


The only case I can think of for re-farming 3G would be lack of low-band spectrum for Bell on 5G. Bell did not win any 600 MHz (n71) spectrum. In Bell's RAN markets, they will need to deploy n5, which can be 5 MHz if LTE B5 is re-farmed. At some point they can decommission 3G B5 as well, and get a contiguous 10 MHz of n5 for their 5G coverage layer. My suspicion is they will keep their other low bands (B12 and B13) for LTE for many years to come. Telus and Rogers don't have the same problem, as they can deploy n71 in their markets.

Kristowhy
Model Citizen / Citoyen Modèle

@sheytoon thanks for this amazing reference... it certainly deserves a MEGA bravo! 🙂

 

Some questions:

 

Since operators are currently doing NSA, are all "5G" marketed devices now (including the expensive flagships) NSA-only or do they support SA as well (hybrid)?  You mentioned the industry will move to SA in a few years and I wonder how this will transpire with devices.   Perhaps another device upgrade push for "5G gen2"?  Manufacturers are going to love that if that's the case!

 

You mentioned that all 5G voice calls are currently done using VoLTE.  How will this change once SA begins to be pushed out?  I assume this will move to "Vo5G"?  Will devices need to support NSA and SA concurrently for a seemless "transition"?

 

Many have heard about the lower battery life of devices using 5G.  Is this a direct result of having to use NSA with what appears to be a lot of switching between different mechanisms?

 

And finally, you mentioned that all existing 4G LTE bands can be used for 5G.  Correct me if I am wrong, but it would seem like the 3G UMTS/HSPA network (and the spectrum it is using) is a hurdle to faster 5G NSA deployments.  Could this spectrum currently being used by 3G network be leveraged here?  Isn't this why the US carriers have decommissioned their 3G networks?

 

TIA  

jor123
Town Hero / Héro de la Ville

Not really, I think it was pretty informative! And as straight forward as a subject like that can possibly be... Lol

darlicious
Mayor / Maire

@softech 

The key word in most of what I have read or been given info on the decommissioning of the 3G networks is "begun". Seeing as At&t started at the end of February and only now are users finding they cannot connect to their 3G network that it should be the same for T-Mobile. The difference being if the 3G network is unavailable for T-Mobile customers (and pm customers)then if the 2G network is available the phone should switch to it automatically when using voice services.

@darlicious as like before, begin to shutdown is something to do gradually,  right?  Not a hard shutdown means no 3G at all overnight? 

 

Someone posted earlier said there will be a hard shutdown on July 1.  I am a bit skeptical about that, just want to confirm 

darlicious
Mayor / Maire

@dust2dust 

I took the opportunity to ask when it presented itself.

@darlicious- Thanks for that. If that was posted somewhere earlier apparently I missed it. Unless you asked them yourself. A little bit of Koodo-speak in there for fun.

@jor123 thanks for the feedback. Anything I can do to explain things better?

darlicious
Mayor / Maire

@dust2dust 

Here's the response from customer support....

 

As of July 1, 2022: T-Mobile in the United States (including Puerto Rico and the U.S. Virgin Islands) has officially begun to turn down their 3G/HSPA network.

As a result, the only available network for roaming is T-Mobile’s 2G network. Customers can continue to use Roaming Booster add-ons but will experience differences in coverage and service quality (including 9-1-1 calls)!

 

So now we wait for user feedback on actual service but something is better than nothing or paying the first tier price of $105/month.

@darlicious- I understand. Great info. For T-Mobile customers.

 

We don't yet have working verified confirmation of us being able to roam on it. Excellent of you to ask that customer earlier. That's what we need. Customers need to report back that they saw their phone go to 2G or that they set their phone to 2G and talk worked. Of course we can't make customers do that. But it's what we need.

 

Or any kind of announcement from here, other than vague claims, that state that this is the way forward until volte rolls out, if it does. More rumours and vague claims. I want assertions of fact from people in the know who have the authority to make such assertions. Not second hand, heard through the grapevine, interpreted, rumours that someone said so. That someone must come out and say so.

darlicious
Mayor / Maire

@dust2dust 

From T-Mobile's website....

 

2G (GSM, GPRS, EDGE)

  • Frequencies that can provide 2G: Band 2 (1900 MHz)
  • Voice and data services don't work at the same time when on 2G. You cannot use data while on a call.

And the latest since the last announcement sunset date of the 2G network being at the end of this year...

 

Key Dates

  • As of March 31, 2022, Sprint’s older 3G (CDMA) network will be retired
  • As of June 30, 2022, Sprint’s LTE network will be retired
  • As of July 1, 2022, T-Mobile’s older 3G UMTS network will be retired

We’ve also shared that we plan to retire T-Mobile’s older GSM 2G network as well, but no date has been set. We will update this page with any additional information in the future. 

 

dust2dust
Mayor / Maire

How about we get some verifiable feedback from actual customers who might be able to see the phone flip to 2G or set their phone to 2G-only before we get all excited about this.

Rumours and speculation and unsubstantiated claims are not facts.

darlicious
Mayor / Maire

@softech 

T-Mobile is the only US provider with a 2G network. It is scheduled to be decommissioned at the end of 2022. Public Mobile is actually well positioned in the prepaid market in this regard being the only provider in Canada that I could find with a roaming agreement T-Mobile. They're back to being an industry leader rather than a follower in the prepaid mobile market in Canada!!


@softech wrote:

So, PM roaming customers can use T-Mobile's 2G for voice?

How about AT&T's 2G?


AT&T no longer has 2g.

So, PM roaming customers can use T-Mobile's 2G for voice?

How about AT&T's 2G?

darlicious
Mayor / Maire

@sheytoon 

Thank you. Normally I keep the deLorean parked beside the Univac 5000 but it's currently being held by the CCTS as evidence that I was able to recieve notice from pm before I actually got it. If I get it back I will travel back to the '90's to get T-Mobile's 2G coverage map of the US.

 

@computergeek541 

Yes according to T-Mobile customers without VoLTE enabled devices or 4G LTE capable or compatible devices will have their phones switch to the 2G network to make and recieve voice calls in the absence of the 3G network.

 

I imagine there are plenty of stupid phone owner's feeling pretty flippin' smart right now! I knew that free ZTE Cymbal phone I got earlier this year with my sim card order would come in handy eventually.....lol!

Yeah it's totally possible, I'm not up to date on T-Mobile's legacy deployments.


@sheytoon wrote:

@darlicious 

2G?!? Can I borrow your time machine when you're done with it? 😂

 

The 2G network is totally independent from 4G LTE. 2G supports voice calls on its own, and also provides low speed data. The bands used are B2 and B5 in North America, but different channels / blocks than 3G, 4G or 5G to avoid interference.


II know that AT&T used to have band 5 for 2g, but sn't all of T-Mobile's 2g on band 2?  I suspect that that the HSPA network mostly being on band 4 might have been a factor why the 2g network will be outliving the 3g network.  For now, 2g seems to be the only feasible voice option for Public Mobile customers roaming in the U.S.

@darlicious 

2G?!? Can I borrow your time machine when you're done with it? 😂

 

The 2G network is totally independent from 4G LTE. 2G supports voice calls on its own, and also provides low speed data. The bands used are B2 and B5 in North America, but different channels / blocks than 3G, 4G or 5G to avoid interference.

darlicious
Mayor / Maire

@sheytoon 

Can you explain how voice calls will work on the 2G network in the US on band 2 (1900)? Is that separate from the 4G LTE band 2? Or does it piggyback similar to how 5G needs 4G LTE to work in most cases? It's difficult to find a 2G network coverage map for T-Mobile in the US so I am wondering if the 4G LTE  coverage map suffices as long as a tower has band 2 ( 1900)?

 

Please and thank you.

jor123
Town Hero / Héro de la Ville

That was a pretty interesting read, most of it new to me. 


@sheytoon wrote:

@esjliv this was the Coles notes version 😅


@sheytoon  🤣

@esjliv this was the Coles notes version 😅


@sheytoon wrote:

@will13am for most people who own iPhones or Samsung phones, VoLTE should be supported with a software update. There wouldn't be a need to buy a phone from Telus. Telus could ask Apple and Samsung to enable VoLTE for PM subscribers. I've heard it's in the works, but no idea when it'll get done. Hopefully by end of this year.

 

It's the international "grey market" devices that are going to be a pain for customers. But then again, those devices are probably not supporting VoLTE today on the main Telus brand anyway. I think the phone manufacturers should take a lot of the blame for this. Often they insist on disabling VoLTE in firmware until they test a specific operator's network and sign agreements to sell that phone.

 

Overall, the whole industry dropped the ball on universal VoLTE compatibility. It was so much simpler with 2G GSM.


Therein lies the problem for me.  Nobody is using an iPhone or Samsung phone.  😓

esjliv
Mayor / Maire

Coles notes version @sheytoon  ? 🙂

Thanks for the thorough techy information.

JL9
Mayor / Maire

Thanks for clearing up some of the confusion for me on this. I hope PM does start to prepare for the future (functionality wise) even if it isn't 5G anytime soon