20.15 Cell reselection due to MS rejection "LA not allowed"

3GPP51.010-1Mobile Station (MS) conformance specificationPart 1: Conformance specificationTS

20.15.1 Definition

While camped on a cell of the selected PLMN the MS may need to select a different cell in order to fulfil the normal service state. This ensures that the MS is camped on a cell from which it can reliably decode downlink data and with which it has a high probability of communications on the uplink.

This process goes on while camping on a cell which pertains to an LA which is placed in the list of "forbidden LAIs for regional provision of service".

20.15.2 Conformance requirement

1. In response to a registration attempt, when receiving an LU reject with cause value "LA not allowed", the MS stores this LAI in a list of "forbidden LAIs for regional provision of service", to prevent repeated attempts to access a cell of the forbidden LA, 3GPP TS 03.22, subclause 3.3.

2. If the MS has received the cause ‘LA not allowed’, it shall ignore this fact when selecting a cell to camp on, i.e. it shall not reject a cell for camping on because that cell is part of a LA where this cause has been received, 3GPP TS 03.22, subclause 3.5.4.

3. In response to a registration attempt, when receiving an LU reject with cause value "LA not allowed", the MS continues to perform normal cell-reselection, 3GPP TS 03.22, subclause 4.4.2

4. A new LU attempt shall only be performed when a new LA (or new PLMN) is entered according to the cell reselection procedure, 3GPP TS 03.22, subclause 3.3 and figure 4.

NOTE: LA stands for "Location Area" and LU stands for "Location Update".

20.15.3 Test purpose

1. To verify that if an LU is rejected with cause "LA not allowed" that the LAI of that cell is written into a forbidden list which prevents the MS from performing LU onto another cell in that LA. This is verified indirectly in test purposes 2,3 and 4.

2. To verify that the MS will not reject a cell for camping on because that cell is part of a LA in the list of "forbidden LAIs for regional provision of service". This is verified indirectly by making the MS attempt an emergency call and checking that the channel request message is transmitted on the correct cell.

3. To verify that the MS when receiving an LU reject with cause value "LA not allowed", the MS continues to perform normal cell-reselection:

Cell reselection is triggered if there is a better cell (in terms of the path loss criterion C2) in the same LA, or a much better cell in another LA of the selected PLMN (using the CRH parameter). 3GPP TS 03.22, subclauses 3.4 and 4.5.

4. To verify that a new LU attempt will be performed when a new LA (or new PLMN) is entered, 3GPP TS 03.22, subclause 3.3 and figure 4.

20.15.4 Method of test

20.15.4.1 Initial conditions

Parameters changed from Default values table 20.1.

Parameter

Carrier 1

Carrier 2

Carrier 3

Carrier 4

Carrier 5

Carrier 6

RF Signal Level

(dBV emf() / dBm)

63 / -50

54 / -59

44 / -69

OFF

OFF

OFF

RXLEV_ACCESS_MIN (dBV emf() / dBm)

53 / -60

35 / -78

29 / -84

CRH

14

0

10

LAC

H1111

H2222

H1111

ATT

1

1

1

C1

10

19

15

C2

10

19

15

20.15.4.2 Procedure

a) The SS activates the carriers. The SS monitors all RA requests from MS on carriers 1, 2 and 3 until step e) has been completed. Only idle-paging is sent on all channels.

b) The MS is switched on.

c) When the MS performs an IMSI attach onto carrier 1, the SS shall reject it with cause "LA not allowed".

d) 30 s after the MS has returned to idle mode (channel release after LU reject), the MS is manually commanded to set up an emergency call.

NOTE 1: C2 of carrier 3 > C2 of carrier 1. Carriers 1 and 3 belong to the same LA.

e) The SS rejects the CM service request from the MS, with a CM service reject message with cause value #17 (Network Failure).

NOTE 2: Cause values #4 (IMSI unknown in VLR) or #6 (Illegal ME) lead to unwanted behaviour of the mobile.

f) 10 s after the MS has returned to idle mode (channel release after CM service reject), the SS increases the level of carrier 2 to 65 dBV emf().

NOTE 3: C2 of carrier 2 = 30, now larger than C2 of carrier 3 + CRH.

g) The SS shall accept any LU on carrier 2.

20.15.5 Test requirements

1) After step b), the MS shall respond on carrier 1 within 33 s.

2) In step d), the MS shall access on carrier 3 with a channel request message, within 15 s of being commanded to set up the emergency call.

3) After increasing the level of carrier 2 in step f), the MS shall reselect and access onto carrier 2 requesting an LU within 30 s.

NOTE: 13,75 s to perform running average, 10 s to detect C2 differences, 2,4 s to read BCCH of carrier 2, 1 s to perform RA. Total 27,15 s, allow 30 s.