20.3 Basic cell reselection

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

20.3.1 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.

20.3.2 Conformance requirement

1. While camped on a cell of the selected PLMN ("camped normally"), the MS may need to select a different cell ("normal cell reselection" state). The following events trigger a cell reselection:

1.1 (iii) The cell camped on (current serving cell) has become barred.

1.2 (iv) 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).

The MS will then reselect a new cell in order to fulfil the process goal.; 3GPP TS 03.22, subclause 4.5.

NOTE 1: Criterion (i) is tested in subclause 20.8 (Cell reselection when C1(serving cell) < 0 for 5 s).

NOTE 2: Criterion (ii) is tested subclause 20.16 (Downlink signalling failure).

NOTE 3: Criterion (v) is tested in subclause 20.6 (Cell reselection timings).

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

2.1 (ii) It should not be "barred".

2.2 (iv) The radio path loss between MS and BTS must be below a threshold set by the PLMN operator. 3GPP TS 03.22, subclause 3.2.1.

NOTE 4: Criterion (i) is not relevant for cell reselection and for cell selection it is tested in subclause 20.1.

NOTE 5: Criterion (iv) refers to the C1 parameter.

3. The MS shall be able to calculate correctly the path loss criterion parameter C2 used for cell reselection; 3GPP TS 05.08, subclause 6.4.

4. At least every 5 s the MS shall calculate the value of C1 and C2 for the serving cell and recalculate C1 and C2 values for non serving cells (if necessary). The MS shall then check whether:

i) The path loss criterion (C1) for current serving cell falls below zero for a period of 5 s. This indicates that the path loss to the cell has become too high.

ii) The calculated value of C2 for a non‑serving suitable cell exceeds the value of C2 for the serving cell for a period of 5 seconds, except;

a) in the case of the new cell being in a different location area or, for a GPRS MS, in a different routing area or always for a GPRS MS in ready state in which case the C2 value for the new cell shall exceed the C2 value of the serving cell by at least CELL_RESELECT_HYSTERESIS dB as defined by the BCCH data from the current serving cell, for a period of 5 seconds; or

b) in case of a cell reselection occurring within the previous 15 seconds in which case the C2 value for the new cell shall exceed the C2 value of the serving cell by at least 5 dB for a period of 5 seconds.

This indicates that it is a better cell.

3GPP TS 05.08 / 3GPP TS 45.008, subclause 6.6.2.

5. The MS shall attempt to decode the full BCCH data of the serving cell at least every 30 s; 3GPP TS 05.08, subclause 6.6.1.

20.3.3 Test purpose

1. To verify that:

1.1 The MS meets conformance requirement 1.1.

1.2 The MS meets conformance requirement 1.2.

2. To verify that:

2.1 The MS does not reselect a cell which is barred.

2.2 The MS does not reselect a cell which has a C1 < 0.

3. To verify that the MS calculates the C2 parameter correctly when the CELL_RESELECT_OFFSET, TEMPORARY_OFFSET and PENALTY_TIME parameters are not used.

4. To verify that the MS takes into account the CELL_RESELECT_HYSTERESIS parameter when reselecting a cell in a different location area.

5. To verify that the MS decodes the CELL_BAR_ACCESS and CELL_BAR_QUALIFY parameters from the BCCH every 30 s.

20.3.4 Method of test

20.3.4.1 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)

43 / -70

33 / -80

43 / -70

35 / -78

38 / -75

RXLEV_ACCESS_MIN (dBm)

-85

-90

-90

-85

-67

CRH

10 dB

LAC

different from other carriers

CBA

1

CBQ

0

C1

15

10

20

7

-8

C2

15

10

20

7

-8

The BA(BCCH) list only contains the ARFCNs of the carriers used during the test.

20.3.4.2 Procedure

a) The SS activates carriers 1, 2, 4 and 5. The MS is not paged on carrier 1. The SS monitors carriers 2, 4 and 5 for RA requests from the MS.

b) The MS is switched on.

c) The SS stops paging on all carriers except carrier 2. The level of carrier 2 is increased to 43 dBVemf (C2 becomes 20 dB), and the SS monitors carrier 2 for RA requests from the MS.

d) When the SS receives a response from the MS on carrier 2, it stops paging the MS on this carrier.

e) The MS is switched off.

f) The SS is reconfigured and sets CBA = 1 on carriers 1 and 5.

g) The MS is switched on.

h) After 33 s, the SS starts paging continuously on carrier 1 and sets CBA=1 on carrier 2 and CBA=0 on carriers 1, 4 and 5.

i) When the SS receives a response on carrier 1, it stops paging the MS and waits for 25 s. (The MS should reselect and camp onto carrier 1).

j) The SS activates carrier 3, pages the MS continuously on this carrier and monitors carrier 3 for RA requests from the MS.

k) The SS increases the level of carrier 3 to 53 dBVemf (C2 increases to 30 dB.).

20.3.5 Test requirements

1) After step b), there shall be no response from the MS on carriers 2, 4, or 5 within 50 s.

2) In step c), the MS shall respond on carrier 2 within 20 s of increasing the level of carrier 2.

NOTE 1: 5 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 18,4 s, allow 20 s.

3) In step h), the MS shall respond on carrier 1 within 50 s of setting CBA=1 on carrier 2.

NOTE 2: 33 s for the MS to read the BCCH of carrier 2 (30 s + 10 %), 15 s for the MS to reselect cell 1, since the MS already has a running average on carrier 1, allow 50 s.

4) After step j), there shall be no response from the MS within 50 s.

5) After step k), the MS shall respond on carrier 3 within 20 s.