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Country Border Roaming Issue

Viewing 15 posts - 16 through 30 (of 37 total)
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  • #51651
    jean
    Guest

    Hey guys, thanks for your reply.. most of the complaints come from subs by the coastal line. Our country and neighbouring country is saparate by a strait (sea), which is only about 1km apart. The major city of country A and major city of country B are both by the coastal and facing each other, thus population density by the coastal line of both countries are pretty high.
    Thanks..

    #51652
    jean
    Guest

    Yes Bilal, we already have a mutual agreement with neighbouring country’s network (which using the same set of ARFCN) to use different set of frequencies and BSIC within 2km of the border.

    #51653
    Pan
    Guest

    Sorry, Pix!
    All that I had said in previous post is applied only in connected mode.
    In idle mode a mobile identifies a cell (for cell selection/reselection purposes) according to the ARFCH, as well as CGI (because only cells belonging selected PLMN can take part in reselection process and MS needed to know MCC/MNC before reselection).

    #51654
    Bilal
    Guest

    Pan,

    One correction. Complete CGI is not known in Idle Mode. Only MCC-MNC-LAC and then BCCH-BSIC. MS can’t differentiate between two cells with same MCC-MNC-LAC and BCCH-BSIC even if they have different CGIs. Am I right?

    #51655
    Pan
    Guest

    Well, Bilal ๐Ÿ™‚ – not CGI, more correctly – only Cell Identity plus LAI from SI type3. But CGI = LAI + CI.

    #51656
    Bilal
    Guest

    Thanks Pan, I was wrong ๐Ÿ™‚

    #51657
    paraHO
    Guest

    Wow this is good discussion…

    Pan you said:
    “The only thing that will force MS to select HPLMN from VPLMN Foreign country is suitable cell absence in VPLMN. Suitable cell definition – see GSM 03.22.”

    Now if you see Jean comments the subs MSs are at coast. If you read my comment to Pix you will see I gave example coast location in UK. What I see is, what made MS where sub in own country select VPLMN in another country? In this case it is the location like coastline where this can occur, and as there can be absence of suitable cells for VPLMN…hence MS search for HPLMN where abundance of cells are available.

    Pan, in answer to your reply 1, 2 and 3.

    1) Yes I know this as after SIM activation following power up the ME reads SIM EFIMSI and EFLOCI (GSM11.11). What is being discussed is as above re: border, in this case at coast. The MS will see VPLMN but as absence of VPLMN cells can search HPLMN. I also gave another illustration about re-scanning of SI2 in fringe coverage in rural area (re: T-Mobile, O2, Vodafone). It doesn’t follow that SI5 will follow.

    2) The point I raised earlier, if using -110dBm as HPLMN backstop and VPLMN uses same (-110dBm) then the VPLMN & HPLMN RxLv_Acc_Min will be equal for both, one not lower than the other. How then you overcome the problem? I think sub who ‘live’ or ‘work’ in area will not be happy and be angry to be forced to continually manually select network… I don’t think this is best option.

    3) I have answered this in post to Pix earlier.

    I agree PLMNsel and FPLMN they are separate EFs in SIM. However, data are shared from EF to EF. When a MCC/MNC in the EF PLMNsel can no longer be used and sub attempts to use that MCC/MNC the MS can be barred from attempting using it and the the record of MCC/MNC attempt appears in the Forbidden list. That is the point of FPLMN.

    A detected MCC/MNC not in EF PLMNsel nothing may happen to populate that MCC/MNC data to appear in EF FPLMN. However, where MS attempts to select auto or manually the MCC/MNC for call the network signals MS that MCC/MNC barred the barred MCC/MNC can be updated to EF FPLMN.

    But as Jean say they have agreements about cell arrangements with VPLMN operator. So maybe BSIC+CI+BCCH+Pwrlvl+??? they come to some agreement.

    #51658
    Pix
    Guest

    >> Bilal, Pan,

    Can you summarize ? I’m a “bit” lost.

    MS in idle mode, receives SI2 from serving, stating BCCH(n1)=24.
    MS receives a frequency 24, decodes system information messages –> what are the important fields that are used in order to authorize cell reselection ?

    NCC neighbor = NCC from serving cell ?
    MNC+MCC neighbor = MNC+MCC from serving cell ?

    >> ParaHO,

    No risk of ping pongs ! Example with RXLEV ACCESS MIN = -110dBm in all cells :

    MS camping on hPLMN :
    a belongs to hPLMN
    b belongs to vPLMN
    MS receives RXLEV(a) = -109dBm and RXLEV(b) = -60dBm.
    In this situation, MS will not leave “a” because “a” is still a valid cell (> than rxlev access min). As Pan said, there are other reasons to decide to leave a cell, including effects of interference in UL and DL, so ensure clean frequencies in BCCH.

    CASE 2:
    MS camping on vPLMN :
    a belongs to hPLMN
    b belongs to vPLMN
    MS receives RXLEV(a) = -60dBm and RXLEV(b) = -109dBm
    The MS will not leave cell B, because the rxlev(b) is not below rxlev access min.

    I hope these examples are making sense to you ? As you can see, there is no reason for ping pong.

    At MS switch off (cf Pan’s post), the MS will select a cell that belongs to previous LAC, so it will stay in vPLMN if it was in vPLMN before previous swith-off.

    #51659
    pix
    Guest

    previous post, last line :
    typo error : “at MS swith off” = “at MS switch on”

    #51660
    paraHO
    Guest

    Hi Pix, OK I have no problem with yours or Pan observations on certain types scenarios.. And thanks to all of you willing to discuss this, I do respect it.

    What happens where:

    Case 1
    MS camping on hPLMN :
    a belongs to hPLMN
    b belongs to vPLMN
    MS receives RXLEV(a) = -98dBm and RXLEV(b) = -98dBm.

    CASE 2:
    MS camping on vPLMN :
    a belongs to hPLMN
    b belongs to vPLMN
    MS receives RXLEV(a) = -87dBm and RXLEV(b) = -87dBm

    Additionally, PAN mentioned GSM03.22

    Ok well looking at GSM0322 R99 it says

    4.4.3 PLMN selection
    A PLMN shall be understood to be received with high quality signal if the signal level is above -85 dBm (see 23.122).

    If the HPLMN is not found, the MS shall remain on the VPLMN…

    OK, so as discussion, Jean’s subs MSs are not detecting HPLMN just sometimes, not all the time, and when that happens subs use VPLMN or get barred from use.

    So put GSM 0322 4.4.3 in context with Jean’s subs and the words “If the HPLMN is not found” become important, because at times the MSs are finding HPLMN.

    The question comes what circumstances can there exist, which are set out under GSM 03.22 3.0 Requirement and technical solutions.

    Because this a coast/border issue I do not see same hard principles applying when sub with MS is not home country as opposed to say 400Km away from home (out of radio reach of HPLMN).

    Pix I see the switch ON point you make, but if MS is in-building or at side of building and goes behind buildng at switch ON so NLOS with VPLMN the MS can be getting a mix of signals including HPLMN cells. So at switch ON whilst MS looks to EFLOCI and any LAI in it, the speed of processing may mean the MS may consider VPLMN cells for seconds but with HPLMN cells being detected then it as likely to look to HPLMN. Remember I am discussing coast/border area, not every scenario…

    If you not satisfied with the above then there is of course GSM0322 4.4.3.3:

    4.4.3.3 In VPLMN of home country
    The MS shall periodically attempt to obtain service on its HPLMN. For this purpose, a value T minutes may be stored in the SIM, T is either in the range 6 minutes to 8 hours in 6 minute steps or it indicates that no periodic attempts shall be made. If no value is stored in the SIM, a default value of 30 minutes is used.

    The attempts to access the HPLMN shall be as specified below:

    a) The periodic attempts shall only be performed in automatic mode when the MS is roaming in its home country;

    b) After switch on, a period of at least 2 minutes and at most T minutes shall elapse before the first attempt is made;

    c) The MS shall make an attempt if the MS is on the VPLMN at time T after the last attempt;

    d) Periodic attempts shall only be performed by the MS while in idle mode;

    e) If the HPLMN is not found, the MS shall remain on the VPLMN.

    I do not think manual selection as permenant solution is good, as it suggests network cannot fix problem. If barring is not put in place of Loc-Upd etc then -110dBm as backstop is one element of a number of things that could be done.

    This is just discussion, I not try to change the world ๐Ÿ™‚

    #51661
    paraHO
    Guest

    OK my last post sorry typo the line should read:

    “Because this a coast/border issue I do not see same hard principles applying when sub with MS is in home country as opposed to say 400Km away from home (out of radio reach of HPLMN).”

    #51662
    paraHO
    Guest

    case 1 : stays in hPLMN
    case 2 : stays in vPLMN

    in both case, the MS doesn’t even search for another PLMN. As you quoted from 3GPP:

    ———————————–
    4.4.3.3 In VPLMN of home country
    (…)
    a) The periodic attempts shall only be performed in automatic mode when the MS is roaming in its home country;
    ———————————–

    In my opinion, there is indeed a hard distinction roaming to a vPLMN from same country or vPLMN from another country:

    In the “border” situation, the MS is roaming to another country. So the MS Timer is not activated, and the MS will never try to come back to hPLMN.

    UNLESS the MS looses coverage from vPLMN (case where rxlev < rxlev access min) or some interference issues where the BCCH can't be decoded. Well, that's how i see it...

    #51663
    pix
    Guest

    wrong name… that was me in the previous post ! not paraHO ๐Ÿ™‚

    #51664
    paraHO
    Guest

    Hi Pix (paraHO), what a laugh ๐Ÿ™‚

    What I meant by hard principle is the MSs outside of radio rangeof HPLMN, where as in Jean’s case the MSs are within radio range of HPLMN.

    OK paraHO, err sorry, Pix ๐Ÿ˜‰

    #51665
    pix
    Guest

    paraHO,

    either MS tries to find the hPLMN or it doesn’t:
    1. if it is in foreign vPLMN, it’s another country, so it doesn’t try to search for hPLMN.
    2. if it is in local vPLMN, it’s the same country, so it tries to search.

    the fact that the hPLMN is in radio range doesn’t change this “stupid” MS behaviour. this is clearly a 3GPP limitation.

Viewing 15 posts - 16 through 30 (of 37 total)
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