20.1 Cell selection

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

20.1.1 Definition

Cell selection is a process in which a MS, whenever a new PLMN is selected, attempts to find a suitable cell of that PLMN to camp on. Two methods of searching for a suitable cell are possible, normal cell selection and stored list cell selection. The process 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. Once the MS is camped on a cell, access to the network is allowed.

20.1.2 Conformance requirement

1. The MS shall be able to select the correct (fourth strongest) cell and be able to respond to paging on that cell within 30 s of switch on, when the three strongest cells are not suitable. This assumes a valid SIM, with PIN disabled and ideal radio conditions; 3GPP TS 05.08, subclause 6.1.

2. There are various requirements that a cell must satisfy before an MS can perform normal camping on it:

2.1 (i) It should be a cell of the selected PLMN

2.2 (ii) It should not be "barred" (see subclause 3.5.1)

2.3 (iv) The radio path loss between MS and BTS must be below a threshold set by the PLMN operator. This is estimated as shown in subclause 3.6.

3GPP TS 03.22, subclause 3.2.1.

NOTE: Criteria (iii) is not applicable for Cell Selection.

3. Initially the MS looks for a cell which satisfies these 4 constraints ("suitable cell") by checking cells in descending order of received signal strength. If a suitable cell is found, the MS camps on it; 3GPP TS 03.22, subclause 3.2.1.

4. The MS shall be able to calculate correctly the path loss criterion parameter C1, used for cell selection and reselection; 3GPP TS 05.08, subclause 6.4.

20.1.3 Test purpose

1. To verify that the MS meets conformance requirement 1.

2. To verify that:

2.1 The MS does not select a cell of a PLMN which is not the selected PLMN.

2.2 The MS does not select a cell which is "barred".

2.3 The MS does not select a cell with C1 < 0.

3. To verify that the MS selects suitable cells in descending order of received signal strength.

4. To verify that the MS does not select a cell with C1 < 0.

20.1.4 Method of test

20.1.4.1 Initial conditions

Parameters changed from the default values in table 20.1.

Parameter

Carrier 1

Carrier 2

Carrier 3

Carrier 4

Carrier 5

Carrier 6

RF Signal Level

(dBV emf() / dBm)

48 / -65

38 / -75

43 / -70

33 / -80

28 / -85

OFF

CBA

1

0

0

0

0

RXLEV_ACCESS_MIN

(dBm)

-90

-67

-90

-88

-98

MNC

See Table 20.1c

MCC

002

C1

25

-8

20

8

13

C2

25

-8

20

8

13

For an E-GSM MS carrier 2 and carrier 4 ARFCNs are chosen in the E-GSM band, carrier 1 and carrier 3 ARFCNs in the P-GSM band.

20.1.4.2 Procedure

a) The SS activates the carriers and monitors carriers 2, 4 and 5 for RA requests from the MS.

b) The MS is switched on.

c) The MS is switched off.

d) The SS monitors carriers 1 and 3 for RA requests from the MS.

e) The MS is switched on.

20.1.5 Test requirements

1) After step b), the first response from the MS shall be on carrier 4 within 33 s. There shall be no response from the MS on carrier 2.

2) After step e), there shall be no response from the MS on either carrier 1 or carrier 3 within 33 s.