Could you explain what precludes a CDMA2000 air interface on top of a GSM-MAP core?
On my hard drive, I've got a 226-page PDF file regarding the specifications being worked out for a 1x/3x overlay on a GSM-MAP core (http://208.45.131.70/docs/newsd/CS0008-0.pdf). Thus I'm sure that it's technologically possible.
What matters, however, is whether such a network would be fully compatible with existing, "normal" cdma2000 networks. In other words, whether such a network, while using the same air interface, could also people using CDMA handsets via other carriers roam on it, thus saving an operator who choses a cdma2000/GSM-MAP path from suffering a Nextellian fate. I'm definitely not half as knowledgable on the technological intricacies related to wireless standards as some of the people here, but based on a few of the things that I read in the PDF file, I came away with the impression that such a network wouldn't be compatible with standard cdma2000 networks. Here's some of the lines that sent me to that conclusion (God, what I'd give for Acrobat to have a cut and paste feature):
Page 9 (paraphrasing): While no changes have to be made to the cdma2000 physical layer standard, modifications have to be made to the cdma2000 Media Access Control (MAC) standard, the cdma2000 Signaling Link Access Control (LAC)standard, and the cdma2000 Layer 3 signaling standard.
Page 11: "Compatibility, as used in connection with the standard, is understood to mean: any mobile station supporting MC-MAP operation is able to place and receive calls in any system supporting MC-MAP operation. Conversely, all MC-MAP base stations are able to place and receive calls for any MC-MAP mobile station."
Page 20: "The CDMA MC protocol stack plays the role of the Access Stadium protocols and is extended to support GSM-MAP non-access stadium protocols."
Page 23: "The above standards (a list including the cdma2000 physical layer, MAC, LAC, and Layer 3 signaling standards) provide the cdma2000 Multi-Carrier Mode, IMT-2000 CDMA MC, of the ITU IMT-2000 standards. Upper layer support is provided for the TIA/EIA-41 network, resulting in the MC-41 mode of operation. The cdma2000 system also includes a standard that specifies modifications that are required to support operation using the MAP upper layers, resulting in the MC-MAP mode of operation."
Based on these passages (correct me if I'm wrong), the impression I got was that a 1x/3x overlay on a GSM-MAP core would require the use of an entirely different set of handsets and base stations, at least in terms of the software they handle. Thus while those using this kind of network might be able to roam on other CDMA networks, those using other CDMA networks wouldn't be able to roam on it. This same dilemma is why DoCoMo, with billions of dollars invested in PDC equipment and the know-how to do a W-CDMA overlay on a PDC core, has opted to eventually build out a full-fledged GSM-MAP core for its W-CDMA networks.
wirelessreview.com
NTT DoCoMo in Japan is one 3G pioneer. Driven by a need to increase capacity, it began experimenting with W-CDMA and is conducting multiple trials designed to prove the W-CDMA concept and, at the same time, establish NTT DoCoMo as the early adopter and leading provider of 3G wireless services. The earlier trials were based on NTT DoCoMo’s specification of W-CDMA, and its announced plans to migrate to the 3GPP-defined UMTS specification.
My guess is that Japan Telecom and the South Korean carriers (assuming with the lattter that they go with W-CDMA), in order not to become islands unto themselves, will do the same thing.
Eric |
