So what is GSM1x?
Background
In the world of mobile communication. There are usually two parts, one is called the core networks(CN), the other is called radio access networks(RAN).
Currently two major types of CN in the world are IS-41 and GSM-MAP. Three major types of RAN are GSM, TDMA(IS-136) and CDMA(IS-95/2000)
GSM-MAP uses GSM as its air interface part where IS-41 has multiple flavors of air interfaces as its RAN such as IS-136, IS-95 and AMPS.
The main function of CN is to manage various services such as call setup, messaging, location and roaming etc. Oh, and billing of course:-)
The main function of RAN is to provide the bearer for the those services.
And all these services are controlled by a bunch of signaling messages(protocols) that are used between phone and RAN, RAN and CN, phone and CN.
The goal of GSM1x is to use CDMA2000 technology for the radio access yet keep the GSM-MAP CN intact.
Just like engineer said, it sounds simple but there are really a lot of things need to be taken care of because the two have very different architectures.
History of GSM1x, or more precisely MC-MAP.
It is indeed not a brand new thing. In 97 Q and Vodafone conducted a series of trials in combining CDMA RAN and GSM-MAP at Newbury England. Here are some old articles about that trial
eetimes.com
cdg.org
The trial made a pretty sound splash at that time, one of the major consequence was that the GSM camp clearly saw the coming threat so they really hurried up to create their version of CDMA radio access, which is the famous you know, WCDMA. Anyway back to CDMA overlay, the following works in the harmonization effort (OHG) led to two versions of cross standards, IS-833 which is the CDMA RAN with GSM-MAP, IS834 which is the WCDMA RAN with IS-41 CN.
On the other hand, the direct result of the Newbury trial is the born of Globalstar phone with GSM capability. As you may or may not know, G* phone uses CDMA technology yet it can use both IS-41 and GSM-MAP type of signaling protocols in satellite mode.
So strictly speaking, Q already had a lot of first hand experiences in building the CDMA on top of the GSM-MAP backhaul(well from OSI model it's actually GSM-MAP on top of CDMA lower layers but what the heck:-))
So this GSM1x is just another step forward.
Of course I believe there will still be many questions need to be answered. One big area I can see is the inter-system operations such as handoff between GSM-GSM1x, CDMA1x-GSM1x, GSM-GSM/95AB, 95AB-GSM1x etc etc. Also don't forget the need of supporting GPRS in GSM1x.
What are the advantages?
1) Cost
It is still not clear how much the equipment costs will be and how that compare to WCDMA. However one need to see that since GSM1x can be used in the existing spectrum, it already has a built in advantage. Also consider the fact that 1x is much more mature than WCDMA at this point so the R&D cost should be much less too.
2) Performance
If you just look at the 1x alone, then it is pretty much even with WCDMA other than the peak rate maybe a little less than WCDMA, however the overall throughput is about the same(same 5Mhz adjusted) And 1x will have higher voice capacity. But if you throw in HDR the equation will change!!!
3) Time to market.
Like I said since 1x is much more mature, so even with the mount of works need to be done, GSM1x should still have a clear time advantage over WCDMA.
Main obstacles against GSM1x?
1) General perception among the carriers
In Euro land, other than their anything but Qualcomm mentality, they are pretty much still living by the over promises by those vendors. Also since there are already that much of money and efforts threw into WCDMA, changing the direction is indeed very hard to do.
2) Money
Unlike CDMA carriers who can move into 3G rather smoothly. GSM guys will spend big chunk of money, be it WCDMA or GSM1x because either way they have to build brand new RAN and use brand new phones. So if there are no major vendors committing into GSM1x then it is very hard to lower the price therefore the carriers will be extra cautious in making such a major move.
Wishful thinkings
So who are the best candidates for GSM1x?
1) China
I really wish Q can convince China into choosing the path of GSM1x. Keep in mind that one of the major reasons that Chinese choosing CDMA is to break the monopoly by the foreign vendors. To be honest, even in the world of CDMA, the competition will be heating up and Chinese are still behind. But things will be different if they leading the charge GSM1x. Doing that will not only give China an early entry to the 3G but will also make China as a leader for the next wave. China should realize that by its size this move will create a snowball effect and totally change the landscape of the telecom world.
So I'm keeping my finger crossed hoping the man in power can see what this will bring to China.
2) All those small carriers that can't compete with the big fished in bidding up the spectrum. Well the choice is obvious. However it is still depend on some major change of heart to happen.
So my wildest dream is this. China(I mean the whole China) leading the charge and GSM1x sweeping through the Asia-Euro continent.
Please don't wake me up:-) |
