GSM and GPRS Gain Momentum

Well, i just changed from GSM to CDMA because it is WAY better, clear voice quality, high speed data....... and my network (Hutch Thailand) also uses SIM cards!
It is CDMA 2000-1x, and my phone is a Sanyo SCP 550 with a SIM card in it. I ca also put this SIM into another SIM enabled CDMA 2000-1x, such as the Motorola v680 or Nokia 2280 and it works right away on this network :)

Not all SIM's are GSM.... just in CDMA they are called "R-UIM" (removable user identity module).
Thanks for reading this....

Regards
Thanh

CDMA because it's better!

Let's not confuse the air interface with the protocols.
What SprintPCS and others in the US selling CDMA service are actually selling is IS-95A, IS-95B, which is more correctly referred to as CDMAOne rather than just CDMA. And CDMAOne's migration path to IMT-2000's 3G is being rolled out now in it's incremental phases CDMA2000 1xRTT, 1xEV, 3x... All are over an air interface called CDMA. Indeed, no one can argue against the spectral efficiency of CDMA and that's why 3 of the 5 accepted adaptations under the ITU's IMT-2000 "3G" umbrella are CDMA. But that's just the air interface.

Likewise GSM used a TDMA air interface, as does Motorola/Nextel's iDEN service. What most people refer to as "TDMA" cellular service in the US and Canada, is actually IS-136 over a TDMA air interface.

Think of CDMA like Ethernet. Over that ethernet you can run, TCP/IP, Apple's AppleTalk, Netware's IPX/SPX, Microsoft's NetBEUI, etc. Saying a network runs ethernet for communication is a little inprecise.

Most migration paths do in fact evolve to a CDMA air interface in the ITU's IMT-2000 3G specification. And there is some increased interoperability built into that spec. Qualcomm does indeed manufacture chipsets for both WCDMA (UMTS), and the various CDMA2000 flavors, so you'd expect some interoperability there.

>They (Qualcomm) have a few patents in the standard. >But like Motorola in the GSM case, Ericsson is the >major patent holder for WCDMA.

Qualcomm's patents are for the CDMA Air interface. The migration path to 3G for GSM providers is WCDMA, but now you're referring to protocol not air interface. You can't DO WCDMA without licensing the CDMA air/radio interface from Qualcomm.

>Signal strength is not a measure of the quality of a >particular phone standard, be it GSM, TDMA or CDMA.

While that's true, the standard does have something to say on the subject. IS-95A and IS-95B (CDMA) run with lower signal strength requirements, and higher number of maximum users per sector. This means the network is more spectrally effecient and cheaper the build out. It follows that you're more likely to be in a better coverage area with a CDMA system, cost and capacity taken into effect. The advantage gets even stronger with CDMA2000 where the power/signal requirements are even less, and the capacity is greater still. If that wasn't the case, GSM and IS-136 would stay TDMA based.

>Add to that GSM short messaging service, SMS, which >isn't provided under TDMA and CDMA

SMS might not be offered over IS-136 "TDMA" in the US but it is in Canada. Further SMS IS offered on virtually all CDMA networks. The thing is that usually it's only implemented in receive only mode. That's not to say that SMS-MO (Mobile originated) isn't in the IS-95 CDMA spec, because it is, as any one can read for themselves in Motorola's online CDMA spec archives. Further, Mobile Originate SMS has been enabled on certain large corporate clients handsets with at least one provider here in Canada.

>the fact that if I want to use my visorphone one day >and my Nokia 8210 the next all I have to do is swap >the SIM card over... My number stays the same, my >phone book gets transferred across because its the >same account.

No disputing that advantage. Better yet though is the day which is nearing where the "SIM" card becomes the essence of the phone. We already have in prototype form Field Programmable DSP's which can be programmed to be a GSM transceiver, or a CDMA transceiver, or to function on a given frequency. Imagine how small your cellphone would be if it didn't have a display, antenna, keyboard, battery, and support circuitry. It would likely be the size of a Compact Flash card or so. Now imagine that you could choose the user interface that you liked, be it a Nokia handset, or a Palm or whatever. The point is you provide the card to the cellular carrier to program to their networks parameters. Then you insert it into your device which just provides the display, interface, battery etc, and voila. You could just as easily present that programable DSP card to another carrier running a different network, and now the SAME handset runs on a totally different network. That makes even more sense to me. That way the providers keep the control over the operational parameters of the devices on their network, as they deserve, and you don't end up with a $500 paperweight because you move out of their coverage area, or their rate plans loose touch with reality. True you have SOME of that benefit with a GSM handset and it's SIM card, but only if the handset isn't subsidy locked, and you can only move to another GSM network on a compatible frequency band.

>The us TDMA networks uses 3 time slots, while the GSM >network uses 7, allowing more costumers per channel >and frequency band.

And it needs them, especially with 2.5G data loads. From the GSMWorld site:
"At the current stage of development most are offering one timeslot upstream and two/three timeslot downstream operations-although the Ericsson R450 will provide four timeslots downstream. At 14.4kbit/s per timeslot, this gives potential data throughput speeds of 28.8kbit/s or 43.2kbit/s downstream-under ideal conditions and where there is sufficient network capacity."

Imagine the fun trying to find enough timeslots for 144Kbps, over and above the voice timeslots.

Hence the CDMA benefit, which get spectrally more efficient with it's evolutions, and high speed data additions, not less so.

>3G will use WCDMA (Wide-Band CDMA) in conjunction >with FDMA.

Not so simple. If you're a GSM provider, then your 3G implementation will likely be WCDMA yes, but your migration path and end implementation of 3G IMT-2000 will be different for CDMAOne (IS-95) providers.
See http://www.cdg.org/3GPavilion/Detailed_Info/3G_fact_sheet.pdf for a brief look at the flavors of IMT-2000. It's not the best source, just the nearest one I could lay my browser on while I type.

-Craig Bowers