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Author Topic: GSM Vs CDMA  (Read 10591 times)
RanTen
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« on: January 16, 2003, 13:15:22 UTC »

Hello,

Found a lot of information on both CDMA and GSM technologies.....but one question remains unanswered.

Can both technologies talk to each other???

In India we use GSM, but very soon a major telecom operator is going to introduce the CDMA spec... So anybody using a CDMA instrument is reachable or not???

Can both techs exist side by side?

Look forward to some information

Thanks

RanTen
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« Reply #1 on: January 16, 2003, 17:23:24 UTC »

CDMA and GSM can not talk over the air or via a standard switch.

There must be some kind of mediation device used. Typical solutions include:

MAP interworking gateways
These operate at the MAP level translating the various MAP messages from one technology to another

Dual/Multi Technology SMSCs
SMSCs that can support 2 or more technologies at the same time can easily support message handover between the two technologies.

SMPP Routing Entities
These are SMPP-based routing nodes that sit above message centres, routing messages between them. Given an SMPP message is multi-technogy compatible, it is possible to relay an SMPP message from one technology to another using these gateways
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RanTen
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« Reply #2 on: January 17, 2003, 05:17:10 UTC »

Hi Cormack,

Thanks for the reply.

So as I understand you, the Cellular Suppliers have to install these technologies, right?

So in case one supplier is on GSM and the other is on CDMA, both operating in the same area - both need to use the technologies outlined by you. And if in case either  dosent...then subscribers from one operator cannot contact subscribers using the other operator, right?

Your inputs will be valuable

Thanks
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« Reply #3 on: January 17, 2003, 11:33:00 UTC »

you are exactly on the point. There are two problems in general that worsen this problem:

ANSI-41 (CDMA & TDMA) has very poor handover abilities
GSM and ANSI-41 (CDMA & TDMA) cannot talk directly.

In the US alone, given large deployments of TDMA, CDMA and GSM, there are several companies dedicated to inter-carrier routing. It is a big business and has some very complex software in place.
« Last Edit: October 29, 2003, 14:33:35 UTC by [email protected] » Logged

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RanTen
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« Reply #4 on: January 18, 2003, 08:13:07 UTC »

Hi Cormac,

Thanks a ton for that information.

Cheerio
RanTen
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bendigo
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« Reply #5 on: February 05, 2003, 01:01:42 UTC »

Hi,

You mentioned...

"In the US alone, given large deployments of TDMA, CDMA and GSM, there are several companies dedicated to inter-carrier routing. It is a big business and has some very complex software in place. "

... can you tell me who there companies are...

~cheers
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« Reply #6 on: February 05, 2003, 11:08:19 UTC »

TSI, Mobilespring, Syntegra, LogicaCMG, Inphomatch, Illuminet, TCS to name a few
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bendigo
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« Reply #7 on: February 05, 2003, 22:43:18 UTC »

thanks for that...

Given that GSM and CDMA cannot talk to each other....
And that 3 solutions was posted for mediation devices....

Which of these solutions solves the issue of allowing 11character alphanumeric sender ID to cross from GSM to CDMA  ... so that the recipient can be confident that the message was from a reliable source and not a hoax....
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« Reply #8 on: February 06, 2003, 13:15:32 UTC »

AFAIK, ANSI-41 the underlying address model used by TDMA and CDMA does not support alphanumeric addressing.

This means that translating an alphanumeric-addressed message to CMDA or TDMA, must introduce a numerical replacement for the alphanumeric address.

But TDMA supports apphanumeric callback identifiers that can be grouped with numbers.. ref. callback_num_atag TLV.

what this allows the ESME do is to send a number in a callback_num TLV and follow it with a callback_num_atag TLV containing an alphanumeric tag.. this tag displays on the phone in the callback number list instead of the associated digit sequence.. but the callback or reply message is sent to the actual callback number.

So basically.. you can't accurately map alphanumeric addresses onto CDMA or TDMA.

Also for inter-carrier routing, alphanumeric addresses would cause lots of problems

Someone with more TDMA/CDMA exposure may be able to clarify the above with more detail
« Last Edit: February 06, 2003, 14:39:10 UTC by [email protected] » Logged

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bendigo
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« Reply #9 on: February 07, 2003, 04:52:55 UTC »

thank you for all this...

looks like you have answered my question unless someone has any brilliant innovative solution....

I can't seem to understand if this was the case then what other aspects of ANSI-41 (CDMA, TDMA) SMS technology makes it better than GSM....

.... ultimately will the two technologies exist or will one be more dominant than the other?
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Zippster
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« Reply #10 on: February 10, 2003, 17:05:20 UTC »

 IMHO, the answer to this could create a debate, if not,
 a "holy war". I am not really on any side, both technologies
 have great things to offer and suffer some drawbacks...

 Anyway, I think GSM is looking for a CDMA air interface
 in the future (W-CDMA? a non qualcomm CDMA,
 please correct me if Im wrong) and the
 CDMA world is adopting GSM "features" along the way...

 I would see a convergence in the future rather
 than one technology being dominant over the other...

 Just my 2 cents...
 
« Last Edit: February 11, 2003, 06:11:53 UTC by Zippster » Logged

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« Reply #11 on: August 21, 2003, 10:58:43 UTC »

hi

Base on all the mail, I have understood that it is not possible to send sms direct from a GSM network to CDMA/TDMA network.  Wink

I will assume that this is a technical constraint, since as mentioned in the mail, a mediation device is required to bridge up the shortcoming.

My queries over here is what is the underlying constraint to restrict sms to be sent direct to CDMA/TDMA network.

I have also heard abt CDMA network is only capable to receive sms only.. it is true.... Huh

Will appreciate any kind soul to feedback..

Regards
Oliver
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« Reply #12 on: August 21, 2003, 15:48:12 UTC »

The physical encodings used on both technologies (GSM & CDMA) are different.. you just cannot inter-change them without an inter-carrier gateway that does the conversion. Same applies to GSM<->TDMA and even CDMA<->TDMA.

There is no problem sending messages to the networks.. (it can be done over an SMPP connecton to the network or to a clearing house service that can access the said TDMA/CDMA network). But from a handset to handset perspective.. its just not directly possible to send messages from GSM networks to ANSI (CDMA/TDMA) and vice versa.

There is also problems doing this across CDMA/TDMA networks.. i.e subscribers in one CDMA network cannot easily send messages to subscribers in another CDMA network without SS7 inter-change being used or inter-carrier SMPP links etc.

this is because of a flaw in the design of CDMA & TDMA..their numbering model based on 10-digit MINs (Mobile Identity Numbers) making roaming a problem.

GSM on the other hand properly considered roaming and interchange and does this flawlessly across SS7 regardless of where both networks are and where both subscribers are roaming.

CDMA can send/receive messages.. its not MT only.. same applies to TDMA

Also note the comment that one user made earlier on in this thread.. the future evolution of GSM will be to adopt a CDMA radio interface whilc CDMA will migrate toward a GSM MAP (encoding).

CDMA radio technology is far more superior to GSM and can pack much more parallel calls into the same bandwidth. GSM on the other hand has a much more sensibly designed roaming and interchange model and the replaceable SIM concept is also something CDMA does ot (yet) have.
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oliverchan
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« Reply #13 on: August 22, 2003, 05:30:07 UTC »

Hi Cormac

Thanks for the information..This is indeed helpful as i'm working out a proposal project for my company.

So in conclusion, it is just not possible to send SMS from a GSM network to CDMA/TDMA without a gateway sitting in between of the 2 network to does the coversion..

Will it be possible if you can let me know what are the specification for both GSM and CDMA/TDMA that dictate the different in the format and the physical encoding for the 2 technologies that forbid the sending of SMS. Grin

It will also be useful if i you can let me know, if there is any website of which i'm able to find out a list of operators in the word that are not using GSM network.

Your help will be much appreciated Smiley
Oliver  
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« Reply #14 on: August 22, 2003, 10:10:19 UTC »

Quote
Will it be possible if you can let me know what are the specification for both GSM and CDMA/TDMA that dictate the different in the format and the physical encoding for the 2 technologies that forbid the sending of SMS. Grin

There just different!.. you can speak Chinese to an English speaking person and discover that you are not understood.. there's no point trying to make a list of words that are different between the two languages.. fact is they are two different languages and if the entities communicating cannot speak a common language, then communication is not possible. This is what happens between GSM and ANSI.. the messages are two different formats that cannot be inter-changed on the fly. The same occurs with software built fo Mac and not working on PC etc..
In Japan, their home-grown PDC technology is very popular but GSM and ( think) CDMA is making its way there.. they are going to have the same problem and in fact some networks already have systems to relay messages from GSM to PDC, completely decoding one format and re-encoding as the other along the way.

mobilesms.com provides a list of SMSC deployments World-wide.. not sure if that includes technology.. but its worthin looking into. Otherwise I don't know of where to look.

One other point and I'm making this because I've seen the idea thrown around in the US where this whole issue of ANSI Vs. GSM has been played out a bit...

Many US networks deploy one of (TDMA and CDMA) and GSM (1900 band).. most are actively trying to migrate subscriber base over to GSM but cannot do this overnight as their GSM coverage is usually poorer than their existing CDMA/TDMA investments which would have wider penetration in coverage terms.

But given that the master plan is to migrate people towad GSM in particular because it is a fundamentally superior technology in terms of roaming and interchange, some have or are considering using message redirection platforms to tie in their ANSI networks with their GSM networks allowing their ANSI subscribers to have a pseudo presence in a GSM environment.

What happens here is that every TDMA/CDMA subscriber gets alocated a full IMSI and GSM directory number. They also get provisioned on the carrier GSM HLRs to have a "special" switch for incoming message deliveries as opposed to the normal switch used to relay GSM traffic to the GSM handsets.

So when a GSM subscriber from any network world-wide, sends a message to one of the subscribers, his message firstly involves looking up the subscriber and this eventually results in the US carriers HLRs being queried.. the result returned to the GSM network is that subscriber is available and contactable at a given "switch".. so the GSM network proceeds to deliver its message to that "switch"..

Thing is however, that the "switch" he thinks is a switch is in fact a gateway that is converting the incoming MT (mobile terminated) message into a mobile originated message, relaying it to one of the carriers GSM SMSCs and then the SMSCs converting it to a TDMA/CDMA message and forwarding it to the real ANSI subscriber.

As these subscribers eventually start to migrate to GSM.. they are reprovisioned to be serviced from the actual GSM MSCs and not the redirection platform.2.. and that transition is completely seamless.

In reality, most US networks are performing inter-carrier messaging using leased lines and SMPP to exchange messages. In most cases, 3rd party inter-carrier entities are hosting these services and sharing in the revenue collected as the messages are relayed.

However, given the more dramatic usage of SMS in Asia in general, I think the message redirection approach is a better way to go for any carrier because it unifies the subscriber base on a single technology which in 3G terms is going to be the ultimate common technology anyway.
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« Reply #15 on: August 26, 2003, 01:03:06 UTC »

Hi Cormac,

Interesting discussion.
In NZ it is possible to send sms from mobile handset of GSM network (Vodafone NZ) to mobile handset of CDMA network (Telecom NZ) .... and vice vesa. Both networks come up with the originating number for reply functionality.

I guess that there must be some sort of interoperability agreement between the networks.

Currently GSM network allow sms to be sent from many countries world wide to handsets in many other countries. Is this the same for CDMA?

You mentioned most US networks are performing inter-carrier messaging using leased lines and SMPP to exchange messages. In most cases, 3rd party inter-carrier entities are hosting these services and sharing in the revenue collected as the messages are relayed.

Do you know of any companies able to accept messages via SSL/XML and relayed back to NZ CDMA or GSM SMSC and then forwarded onto the mobile handsets?

~regards
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« Reply #16 on: August 26, 2003, 11:56:33 UTC »

On the GSM <-> CDMA, there would have to be some kind of mediation that handles the conversion.

CDMA & TDMA have problems when it comes to relaying messages to other networks.. you may find limited relay taking place in Australia or NZ because of a more comfortable inter-carrier environment where the networks can work around the issues.

But when you consider full blown international SMS... it is literally impossible to do this.

The issues are complex but revolve around a very limited specification that is traditionally designed to deliver messages using 10-digit numbers called MINs. these just don't measure up to the smarter design of GSM where it uses 15-digit IMSIs in inter-carrier exchange.

As for companies that offer relay of SMS to NZ.. you'll need to do some google searches and locate these guys and ask them yourself.. we don't recommend services etc.
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« Reply #17 on: May 08, 2006, 22:04:39 UTC »

Hello,

I'm all new to the SMS world (from a technical non-layman perspective), and I'd just like to ask whether all the above is the reason why Argentine and other Latin American CDMA networks can never receive SMSs sent from European GSM networks...

I've been looking for a service that can send SMS that way, but after several months' search, I have come up with nothing. I'm glad I finally found a technical community that might be able to answer this for me once and for all  Cheesy

So... if neither the European GSM nor the Latin American CDMA networks have such converting equipment in place, does that mean that SMS from the former to the latter is impossible?
And if so, why is it that the other way works just fine (i.e. SMS from Argentina CDMA to UK GSM)?
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