Tetra2 / Teds

[Raccon]

This is from another discussion but I thought it deserved a more detailed response in a separate thread:

Hu?
TETRA 2 is just a data enhancement, and a poor one at that considering how poorly it is integrated with the rest of TETRA.
To me it looks like ETSI just stole the US TIA-902 standard. (That came out of the P25 process, by the way):evil:

TETRA 2 - TETRA Enhanced Data Service
ETSI is currently defining TETRA Enhanced Data Service (TEDS), a new air interface standard to increase TETRA data speeds up to 30-150kbit/s. TEDS will be more than 10 times faster than multi-slot packet data.
TEDS will need significantly more radio spectrum and capacity than TETRA, so TEDS carriers will be dedicated to high-speed data and cannot be used simultaneously for voice. This will raise the cost of network upgrades in the same way as multi-slot packet data, although it will provide a significantly better service.
TEDS coverage at the highest speed will not be the same as TETRA coverage, so the highest-speed TEDS service will only be available over a limited range, although the service will be continuously available at a lower speed.
Enhanced data services need more radio spectrum and wider channels, so TEDS needs 50-150kHz compared to 25kHz for TETRA. In the public safety bands this spectrum is restricted, but 50kHz carriers are readily available. Such carriers could also be allocated in a frequency band other than that currently used by TETRA.
Selecting a 50kHz band would make it possible to integrate TEDS into existing TETRA networks, so it is clearly the best choice.

So it takes a new band, uses wider bandwidth, does not integrate with voice, only operates on restricted spectrum, and raises the already excessive cost of the network.

1. If we take "your" definition (VHF, UHF ...) it does not necessarily take a new band, so perhaps we should be a bit more careful with the terminology; I will use 'band' to mean any f1 to f2 or f1 to f2 / f3 to f4 (in case up- and downlink are not directly adjacent) allowed by the TETRA standard, which is what the above quote is referring to.

2. A TEDS carrier may operate in the same band as currently used. E.g. network has been allocated 390-391MHz (base station Tx) then 390.500-390.550 (center frequency at 390.525MHz) for example could be taken for a 50kHz TEDS carrier.
Alternatively the operator may be allocated new frequencies out of his current band, which is mostly a question of availibility and licensing.

3. Since it requires new hardware it involves cost, seems logical and unless I am missing something here it's the same for P25 Phase 3.
In case of at least one manufacturer their current rack is "TEDS-ready", so all you need to do is add the TEDS units (TEDS carrier, maybe a power supply module and an additional combiner, depending on the current configuration/capacity) and update the software. And of course buy some TEDS radios.
However this all being optional the operator can decide if, when and where (which sites) he wants to upgrade and thus how much he wants to invest.

4. I am curious as how P25 is going to implement high-speed data in Phase 3. Do you have any information about that, in particular related to bandwith and frequency spectrum?

5. Does P25 Phase 3 equipment come for free, i.e. does it not raise cost?

 

[N_Jay]

This is from another discussion but I thought it deserved a more detailed response in a separate thread:

It doesn't, but what the hell!

1. If we take "your" definition (VHF, UHF ...) it does not necessarily take a new band, so perhaps we should be a bit more careful with the terminology; I will use 'band' to mean any f1 to f2 or f1 to f2 / f3 to f4 (in case up- and downlink are not directly adjacent) allowed by the TETRA standard, which is what the above quote is referring to.

TETRA was designed with the concept that it would be applied to unused/cleared spectrum. It requires consistent paired spectrum with consistent T-R spacing, and has not been shown to coexist well in mixed use spectrum.
It was originally designed for the 800 MHz European public safety band, and has been expanded into sections of the UHF band for deployment in others regions, only if they meet the requirements of the technology.

P25 was specifically designed to work in simplex, unstructured T-R repeater, and structured T-R bands. It was specifically designed NOT to be band dependant.
It was also specifically designed to be intermixed with analog and other 12.5 kHz and 25 kHz modulation systems.

2. A TEDS carrier may operate in the same band as currently used. E.g. network has been allocated 390-391MHz (base station Tx) then 390.500-390.550 (center frequency at 390.525MHz) for example could be taken for a 50kHz TEDS carrier.
Alternatively the operator may be allocated new frequencies out of his current band, which is mostly a question of availability and licensing.

In other words, TEDS requires new channels, that are not on the same channel spacing as TETRA, and do not carry TETRA voice and data information.
So, TEDS is just separate data channels, that may be handled by the same back-haul and control infrastructure as TETRA, but have no similarity or compatibility over the air.

3. Since it requires new hardware it involves cost, seems logical and unless I am missing something here it's the same for P25 Phase 3.

I don't even know what you are trying to say.

First, my original point of comparison was to why iDEN was better then TETRA.
Second, There is no such thing as P25 Phase 3 at this time.

In case of at least one manufacturer their current rack is "TEDS-ready", so all you need to do is add the TEDS units (TEDS carrier, maybe a power supply module and an additional combiner, depending on the current configuration/capacity) and update the software. And of course buy some TEDS radios.
However this all being optional the operator can decide if, when and where (which sites) he wants to upgrade and thus how much he wants to invest.

And teh point is?
This sounds exactly like adding HSD or HPD to a Motorola P25 system.
(Forgetting entirely that the discussion was about iDEN vs. TETRA)

4. I am curious as how P25 is going to implement high-speed data in Phase 3.

So am I. When it is defined, we will all know.
What I am sure of, is it that the definition will start with requirements defined by the User Needs committee, comprised of system users and not manufacturers.
High speed data (Variants of TIA-902) are already being proposed/marketed/sold by more than one manufacturer and integrated into their respective public safety radio systems.

3. Do you have any information about that, in particular related to bandwidth and frequency spectrum?

TIA-903 specifically addresses the 50 kHZ to 150 kHz channels of the US 700 MHz public safety band as it was originally defined. That band plan is in transition, so the deployment is up in the air. Manufacturers have adapted the concepts developed in TIA-902 to 25 kHz frequencies to deploy on existing bands.
We will have to wait and see where it all ends up, and how much is standardized.

5. Does P25 Phase 3 equipment come for free, i.e. does it not raise cost?

1) There is no Phase 3
2) What the hell point are you trying to make?

 

[citylink_uk]

It was originally designed for the 800 MHz European public safety band

European public safety band is in the 390mhz region.

Rich

 

[N_Jay]

European public safety band is in the 390mhz region.

Rich

I thought TETRA was first released for the 800 MHz (greenfield) band, and UHF followed, but I could be wrong.

 

[SCPD]

I'll cherry pick some of the easier questions / concerns ...

4. I am curious as how P25 is going to implement high-speed data in Phase 3. Do you have any information about that, in particular related to bandwith and frequency spectrum?

Short answer - there will be no high speed data in P25. AFAIK, there is no phase 3 planned. For high speed data, look at Project Mesa. The vision (as I understand it) is the radio on your hip will be P25 and the terminal in your car will be Mesa.

I have a lot of trouble understanding speech through iDEN and fear that I couldn't rely on it under duress.

That's because iDEN is old. It uses VSELP which is a relatively old vocoder. If you replaced the tired vocoder with something comparable to the new half-rate vocoder contemplated for P25 Phase 2 ... you might get 8 or 10 slots - maybe 12 - in a 25 khz channel (compare to 3 to 6 slots now). Perhaps our resident iDEN expert will come forward.

How do you make a Phase 1 subscriber unit from a non-affected area's response team work within a Phase 2 environment if they have trucked out there to help?

Here's the technical answer: When a Phase 1 radio logs onto a Phase 2 capable trunked network, it announces it's capabilities. "Hi, I am radio XYZ with Phase 1 voice, group call, unit call, and data capability." The controller knows that any call grant that includes this radio must be on a Phase 1 channel. It can either deny the registration or accept the radio with decreased overall call capacity. The Phase 2 radios are backwards compatible.

Now comes a more practical answer - most interoperability I have seen is either done at the switch to bridge calls across two or more networks OR as a set of conventional P25 channels. Most mutual aid situations are what I'd call "tactical" ... focused on a specific area or event. Having mutual parties switch to conventional channels allows them to collaborate without the nightmare of assigning roaming profiles across neighboring systems and agencies.

Allowing large numbers of neighboring agency's users to roam onto your trunked network can cause problems. A properly sized system is suddenly bogged down because it must now handle all the "foreign" talkgroups not normally found in the system - at least not for that area (this can be a problem within a single networked system too). All this because 50 or 100 guys drove from one zone to the next with their radios turned on.

Allowing Phase 1 equipment to operate on Phase 2 capable infrastructure is - in my opinion - a means for upgrading an existing Phase 1 system with minimal disruption.

Or, better, have an SDR device that's band agnostic that can coopt existing RF infrastructure with similarly engineered coverage into a larger system (for example, the control channel is on 800, but the radio can be assigned a VHF or UHF voice channel from an existing system that has been connected into the system). I'm dreaming.

Not truly band-agnostic - but most existing P25 Phase I equipment is SDR from the IF all the way back to the speaker mike. There a band-specific front-end that is essentially a superheterodyne receiver. The rest is all "software". There was one Phase 2 candidate that was clearly compatible with existing hardware. A firmware upgrade was all you'd need to make existing Phase 1 radios into Phase 2 radios. I'm uncertain about the current Phase 2 candidate (@ 12000 bps). It may require some slight tweaks of the existing hardware - I'm not sure.

 

[Raccon]

In other words, TEDS requires new channels, that are not on the same channel spacing as TETRA, and do not carry TETRA voice and data information.
So, TEDS is just separate data channels, that may be handled by the same back-haul and control infrastructure as TETRA, but have no similarity or compatibility over the air.

That seems to be correct.

I don't even know what you are trying to say.

I won't disagree with that statement.

First, my original point of comparison was to why iDEN was better then TETRA.

Nope, here is the exchange started from your post #6 in the other thread where you were clearly comparing TETRA to P25. I quoted you then:

P25 also has a feature set determined by the users in concert with the manufacturers, and has methods to enhance and expand the standard as well as implement non-standard enhancement if required for the application.

TETRA can also be enhanced (keyword: TETRA2) and the TETRA MOU includes not only manufacturers but also users.

To which you responded with the text in italic letters about TEDS. No iDEN is/was involved here.

And teh point is?

To show that TETRA can and is being enhanced, and that higher data rates are based on user requirements.

TIA-903 specifically addresses the 50 kHZ to 150 kHz channels of the US 700 MHz public safety band as it was originally defined. That band plan is in transition, so the deployment is up in the air. Manufacturers have adapted the concepts developed in TIA-902 to 25 kHz frequencies to deploy on existing bands.
We will have to wait and see where it all ends up, and how much is standardized.

Since they also use 50 kHZ to 150 kHz channels in a dedicated band then why do you criticize TEDS so harshly?

1) There is no Phase 3
2) What the hell point are you trying to make?

You said '...and raises the already excessive cost of the network.' - that applies to most if not all enhancements that require new / additional hardware - regardless of system, i.e. it's not a TETRA specific "disadvantage".

Short answer - there will be no high speed data in P25. AFAIK, there is no phase 3 planned. For high speed data, look at Project Mesa. The vision (as I understand it) is the radio on your hip will be P25 and the terminal in your car will be Mesa.

Thanks for the info, I will take a look at it sometime.

 

[N_Jay]

Nope, here is the exchange started from your post #6 in the other thread where you were clearly comparing TETRA to P25. I quoted you then:

To which you responded with the text in italic letters about TEDS. No iDEN is/was involved here.

To show that TETRA can and is being enhanced, and that higher data rates are based on user requirements.

P25 was compared to TETRA,
My position that P25 had a better user driven enhancement process was refuted with the TETRA 2 example.
I countered that TETRA 2 is hardly an enhancement to TETRA (More of a parallel air interface for data only), and used iDEN as an example of a TDMA protocol that had true data enhancements rather then the method TETRA took.

Since they also use 50 kHZ to 150 kHz channels in a dedicated band then why do you criticize TEDS so harshly?

I didn't criticize it harshly, I just pointed out that it is a manufacturer driven standard, not a user driven standard. I stand by this fact.

You said '...and raises the already excessive cost of the network.' - that applies to most if not all enhancements that require new / additional hardware - regardless of system, i.e. it's not a TETRA specific "disadvantage".

Because reasonable costs for networks of many sizes is a user need for public safety, and one that TETRA does not consider at all.

 

[DaveNF2G]

Because reasonable costs for networks of many sizes is a user need for public safety, and one that TETRA does not consider at all.

Which is not surprising, given that TETRA and P25 were developed in completely different economic/political environments. TETRA is a government project that assumes that government money will fund the resulting systems regardless of actual cost. P25 is a cooperative user-manufacturer project that cannot assume that large amounts of cash will be available to fund actual deployment of any system.

iDEN, since it is part of the discussion thread, is strictly manufacturer driven and was developed originally in the standard manufacturer development cycle where profitability was a primary concern. Recent "enhancements" to iDEN that appear to have been spurred by user input (particularly from public safety and other governmental users) do not transform iDEN into anything comparable to P25. It is still consistent with the business model - give the customers what they want as long as it is profitable to do so.

 

[n4voxgill]

give it up.

 

[N_Jay]

give it up.

I have!

(Retaining the right to add further if/when someone posts incorrect information)