Re: [dispatch] SIP and GSM/UMTS with OpenBTS

[Ivo Sedlacek <[e-mail]>]

Hello Tim and all,



if I understood the proposal correctly, in comparison to 3GPP architecture you propose:

- UEs are unchanged

- BTS

                - uses regular Um reference point towards UEs

                - has a new SIP based interface replacing ABis reference point

- BSC, MSC, HSS, SM-SC, ... collapse into one functional entity "SAS/Asterisk/SMQueue". This new functional entity:

                - uses the new SIP based interface replacing ABis reference point towards BTS

                - uses another SIP based interface towards remote networks



Can you please clarify what's the intended business case where the proposed solution is supposed to be superior over the existing 3GPP solution?



E.g. can you please clarify whether you indent to specify a solution for:

a) carriers with license to use the licensed GSM bands?

b) individuals/corporates without license to use the licensed GSM bands?

c) anyone else?



The original mail suggested b) but then you referred to a) in your mail stating "But more typically carriers with spectrum licenses are looking for an economical way to get into rural areas."





If a), such solution can be deployed anywhere where there are existing GSM bands in use. However, it will likely require implementation of the full 3GPP feature set which carriers offer today, including supporting regulator's requirements, support of handovers, integration with other operator subsystems (e.g. billing, operation & maintenance subsystems, ...). Or do you believe that some existing requirements are unnecessary for deployments in carrier networks?



You seem to claim above that your proposal can be more economical than existing solution. Given that new protocol would need to be defined and functional entities newly developed and tested, I fail to see how this can be more economical than deployment of existing products which are already developed, tested, mass produced and mass deployed. Can you provide some numbers supporting your view?



https://www.usenix.org/conference/nsdi13/technical-sessions/presentation/heimurl just proposes new functionality to be added, unrelated to any potential replacement of ABis reference point with SIP based interface.





If b), then such solution can be deployed only in countries where there is no license needed. You list Sweden as one with UK and Netherlands with question marks. Also Antarctica was mentioned.



Can you please provide a reference to regulators' document enabling usage of GSM bands without license in each of those countries?



How will interferences be avoided if several individuals/corporates start using the same GSM band in the same location, particularly if each starts using power enabling "potential 20 mile radius even for a single cell"?



Furthermore, even if all of Sweden, UK, Netherlands and Antarctica enable usage of GSM bands without license, this is still quite limited market. If the solution is limited only to those countries, even if the required feature set is smaller, there is little economies of scale.



Kind regards



Ivo Sedlacek



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