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Request: The information about 2G/3G co-LACHi all, I'm collecting the information about 2G/3G co-LAC for our local operator. Your responses are very appreciated if you can provide the following information.

 1. Country or Region2. Operator name3. Does the 2G/3G system which cover the same area deploy the same LAC? If Not,is it possible that lots of Location Updates generated?4. Does the 2G/3G use the common core system?

Thanks and Best Regards,Wang Kui

Posted: 2008-11-27 14:14 by Zaher Zeitouneh View Properties Reply

Hi WangI've heard once that vodaphon in Portugal has such a strategy (Commomn LAC 2G-3G)As for your 3rd question I think that the main advantage of this strategy is toreduce the number of LAURgdsZaher

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Edited: 2008-11-27 17:03 by Christian Mathis View Properties Reply

Hi Wang,

I do not have direct answers to your questions, but the following might also beuseful:

In 2007, I was on a project in Egypt (Etisalat) where the customer wanted to imp

lement such a strategy. The main issue was that they considered a change of thestrategy in a commercially operating network. In cooperation with GSDC Italy, wemade a brief impact study with the conclusion and recommendation to NOT implement such a strategy, see high-level statement to customer's NW Senior Managementbelow:

The recommendation is to use different Location Area Identity (LAI) and RoutingArea Identity (RAI) for the GSM and WCDMA networks. If the same LAI / RAI are used for overlapping 2G/3G networks, a consequence is that the GSM subscribers arepaged in the WCDMA network and vice versa. Since most GSM networks have a largenumber of subscribers this could generate a heavy paging load in the WCDMA network.

Using different LAI / RAI for GSM and WCDMA implies that a LA/RA update will take place each time the UE makes Inter Radio Access Technology (IRAT) cell reselection. If WCDMA for example covers only a city area there will be a distinct LA/R

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A border in both systems where the WCDMA coverage is discontinued.

Different requirements of GSM and WCDMA in terms of coverage and capacity as well as differences given by the nature of the two technologies (e.g. constant cellborders in GSM vs. cell breathing effect in WCDMA) lead to a varying overlap ofthe service areas. This means that intersections of LA/RA are a consequence that cannot be completely avoided.

Thus, same LA and RA can theoretically be used, and might give benefits (e.g. minimal or no LA/RA updates while doing IRAT cell reselection). However, this benefits might fluctuate, e.g. because of varying traffic levels in WCDMA cells andthe resulting variation of the WCDMA service area. Moreover, such a configuration requires more initial conditions than simply having the same MSC. Some are related to MGw and, in general, the entire Core Network structure, so it is not a straightforward implementation. Furthermore, there is a lot of effort required from a Data Transcript point of view which is estimated in the range of several weeks since it has to be coordinated and aligned with other activities. The service availability might be as well impacted for certain periods.

Another disadvantage is, as indicated above, that there is unnecessary paging load generated in either the GSM cells or the WCDMA cells of the same LA/RA. Thisalso means that the paging capacity for GSM and WCDMA could not be optimized individually; a dimensioning compromise is required. Statistics from [Etisalat] 2Gand 3G paging traffic reflect that there is much more 2G paging activity and load than for 3G.

A survey on numerous other Ericsson markets has shown that there is only one reference market where 2G/3G is implemented with the same LAC [Vodafone Portugal] .

Best Regards,

Christian Mathis