8.4 Measurements in CELL_FACH State (3.84 Mcps option)
25.1233GPPRelease 17Requirements for support of radio resource management (TDD)TS
8.4.1 Introduction
This section contains requirements on the UE regarding measurement reporting in CELL_FACH state. The requirements are split in TDD intra frequency, TDD inter frequency, FDD and GSM measurements. These measurements may be used by the UTRAN, e.g. for handover decisions. The measurements are defined in [14], the measurement model is defined in [15] and measurement accuracies are specified in section 9. Control of measurement reporting is specified in [16] and parallel measurements are specified in section 8.2. For the description of the idle intervals see [14].
8.4.2 Requirements
8.4.2.1 UE Measurement Capability
The UE shall be able to monitor up to
– 32 intra frequency TDD cells (including serving cell), and
– 32 inter frequency cells, including
– TDD mode cells distributed on up to 2 additional TDD carriers and
– Depending on UE capability, FDD mode cells, distributed on up to 3 FDD carriers.
– Depending on UE capability, 32 inter RAT GSM cells.
The requirements in section 9 on P-CCPCH RSCP measurements are applicable for a UE performing measurements according to this section. For inter-frequency FDD, TDD and GSM cell re-selection, measurement occasions as specified in [16] and idle intervals as described in [14] are used to find and measure on other cells.
It is defined below how the measurements on different systems and modes are performed given the time allocated to that system. The requirements in this section are based on the assumption that the time during the measurement occasions and idle intervals that is allocated to each of the different modes and systems shall be equally shared by the modes which the UE has capability for and that are in the monitored set signalled by the network.
The UE is required to measure periodically once every time period Tmeas on each of the modes and systems, FDD interfrequency cells, TDD interfrequency cells and GSM carriers, for which the corresponding parameter NFDD, NTDD and NGSM is set to 1, within the measurement time Tmeas
ms
where the following parameters are defined:
NTDD = 0 or 1. If there are inter-frequency TDD cells in the neighbour list NTDD=1, otherwise NTDD=0.
NFDD = 0 or 1. If the UE is capable of FDD and there are FDD cells in the neighbour list NFDD=1 otherwise NFDD =0.
NGSM = 0 or 1. If the UE is capable of GSM and there are GSM cells in the neighbour list, NGSM=1, otherwise NGSM =0.
M_REP is the Measurement Occasion cycle length in number of frames as specified in [16].
NTTI is the number of frames in each measurement occasion, equal to the length of the largest TTI on the SCCPCH monitored by the UE. FACHs that only carry MBMS logical channels (MTCH MSCH or MCCH) are excluded from measurement occasion calculation.
For 3.84 Mcps TDD UE capable of MBMS reception and if MBMS reception is active, during Measurement Occasion the UE shall:
– Start to switch back to its serving cell frequency 1 timeslot prior to the start of the MBMS reception
– Switch back to its target inter-frequency within 1 timeslot immediately after the last MBMS reception.
The FACH Measurement Occasion of NTTI frames will be repeated every NTTI * M_REP frame.
Table 8.6B: K values for each NTTI value
NTTI |
K |
1 |
3,4,5,6 |
2 |
2,3,4,5 |
4 |
2,3,4 |
8 |
1,2,3 |
8.4.2.2 TDD intra frequency measurements
During the CELL_FACH state the UE shall continuously measure identified intra frequency TDD cells and search for new intra frequency TDD cells in the monitored set. If a measurement occasion is activated, intra frequency measurements can be performed between the measurement occasions.
In case no measurement occasion is activated, in order for the requirements in the following subsections to apply, the Beacon timeslots of the intra-frequency TDD cells indicated in the measurement control information shall either be synchronised with the Beacon timeslots of the serving cell, such that the UE can measure an intra-frequency cell TDD cell at least once every frame for the slot allocation case in use in this cell. The UE shall be capable of intra frequency measurements during active DL timeslots.
8.4.2.2.1 Identification of a new cell
The UE shall be able to identify a new inter frequency TDD detectable cell belonging to the monitored set within Tidentify intra ms, where Tidentify intra is specified in section 8.1.2.2.1.
In the case that MTCH is being received, the UE shall be able to take identified cells into use for MTCH combining purposes within Tidentify intra ms.
If more candidate cells are identified than the UE has combing capability, then cells ranked in decreasing MTCH reception quality shall be considered for combing purposes.
8.4.2.2.2 UE P-CCPCH RSCP measurement capability
In CELL_FACH state the UE shall be capable of performing P-CCPCH RSCP measurements for Xmeasurement intra identified intra-frequency TDD cells of the monitored set with a measurement period for intra-frequency P-CCPCH RSCP measurements Tmeasurement period intra, where
Xmeasurement intra is specified in section 8.1.2.2.2
Tmeasurement period intra is specified in section 8.1.2.2.2
The UE physical layer shall be capable of reporting these measurements to higher layers with the measurement period Tmeasurement period intra.
If the UE has identified more than Xmeasurement intra intra-frequency cells, the UE shall perform measurements of all identified cells but the reporting rate of P-CCPCH RSCP measurements of cells from UE physical layer to higher layers may be decreased. The measurement accuracy for all measured cells shall be as specified in the section 9.
8.4.2.2.3 (void)
8.4.2.2.4 (void)
8.4.2.2.5 Timeslot ISCP measurement capability
In CELL_FACH state the measurement period for intra frequency Timeslot ISCP measurements on arbitrary DL timeslots, including Beacon timeslots is 400 ms. The UE shall be capable of performing Timeslot ISCP measurements on the current serving cell for 10 arbitrary DL timeslots. The UE physical layer shall be capable of reporting Timeslot ISCP measurements to higher layers with the measurement period of 400 ms.
8.4.2.2.6 RACH reporting
Reporting measurements in the measurement reports sent on the RACH shall meet the requirements in section 9.
8.4.2.3 TDD inter frequency measurements
When signalled by UTRAN during CELL_FACH state, the UE shall continuously measure identified inter frequency TDD cells and search for new inter frequency TDD cells indicated in the measurement control information.
In CELL_FACH state, measurements opportunities for TDD inter-frequency measurements are provided by means of measurement occasions and idle intervals.
8.4.2.3.1 Identification of a new cell
When measurement occasions and idle intervals are used for inter-frequency TDD measurements, the UE shall be able to identify a new detectable inter-frequency TDD cell belonging to the monitored set within
ms
If the UE does not require measurement occasions and idle intervals to perform TDD inter-frequency measurements, the UE shall be able to identify a new detectable inter-frequency TDD cell belonging to the monitored set within 5000 ms.
8.4.2.3.2 P-CCPCH RSCP measurement period
When measurement occasions and idle intervals are used for inter-frequency TDD measurements, the UE shall be capable of performing P-CCPCH RSCP measurements for Xmeasurement TDD inter inter-frequency TDD cells per TDD frequency of the monitored set.
The UE physical layer shall be capable of reporting measurements to higher layers with measurement accuracy as specified in section 9 with measurement period of Tmeasurement inter.
If the UE does not require idle intervals to perform inter-frequency TDD measurements, the measurement period for inter frequency P-CCPCH RSCP measurements shall be 480 ms.
Where,
Xmeasurement TDD inter is specified in section 8.1.2.4.2.
Tmeasurement_period inter is specified in section 8.1.2.3.2
TMeas is specified in section 8.4.2.1.
T Inter FACH: is equal to (NTTI*10 – 2*0.5) ms.
Tbasic identify TDD inter = 800 ms.
Tbasic measurement TDD inter = 50 ms
NFreq TDDis specified in section 8.1.2.3.2
8.4.2.3.3 (void)
8.4.2.3.4 (void)
8.4.2.4 FDD measurements
The requirements in this section shall apply to UE supporting TDD and FDD.
In the CELL_FACH state when FDD inter frequency measurements are scheduled the UE shall continuously measure detected inter frequency FDD cells and search for new inter frequency cells indicated in the measurement control information.
In CELL_FACH state, measurements opportunities for FDD inter-frequency measurements are provided by means of measurement occasions and idle intervals.
8.4.2.4.1 Identification of a new cell
When measurement occasions and idle intervals are used for inter-frequency FDD measurements, the UE shall be able to identify a new detectable inter frequency FDD cell belonging to the monitored set within
If the UE does not require measurement occasions and idle intervals to perform FDD inter-frequency measurements, the UE shall be able to identify a new detectable inter-frequency FDD cell belonging to the monitored set within 5000 ms.
An inter-frequency FDD cell shall be considered detectable, when CPICH Ec/Io > -20 dB, SCH_Ec/Io > -17 dB and SCH_Ec/Ior is equally divided between primary synchronisation code and secondary synchronisation code.
8.4.2.4.2 UE CPICH measurement capability
When measurement occasions and idle intervals are used for FDD inter frequency measurements, the UE physical layer shall be capable of reporting measurements to higher layers with measurement accuracy as specified in sub-clause 9 with measurement period given by
ms
If the UE does not require measurement occasions and idle intervals to perform inter-frequency FDD measurements, the measurement period for inter frequency CPICH measurements shall be 480 ms.
The UE shall be capable of performing CPICH measurements for Xmeasurement FDD inter inter-frequency FDD cells per frequency of the monitored set and the UE physical layer shall be capable of reporting measurements to higher layers with the measurement period of Tmeasurement FDD inter.
Xbasic measurement FDD inter is specified in section 8.1.2.4.2.
Tmeasurement_period FDD inter is specified in section 8.1.2.4.2
TInter FACH: is specified in section 8.4.2.3.2
Tbasic identify FDD inter is specified in section 8.1.2.4.2
Tbasic measurement FDD inter is specified in section 8.1.2.4.2.
NFreq FDDis specified in section 8.1.2.4.2
8.4.2.4.3 (void)
8.4.2.4.4 (void)
8.4.2.5 GSM measurements
The requirements in this section shall apply to UE supporting TDD and GSM.
In CELL_FACH state, measurements opportunities for GSM measurements are provided by means of measurement occasions and idle intervals.
Measurements on GSM cells can be requested with BSIC verified or BSIC non-verified.
a) In CELL_DCH state, when signaled by UTRAN and when measurement occasions and idle intervals are used for GSM measurements, the UE shall continuously measure GSM cells and search for new GSM cells given in the monitored set.
– In section 8.4.2.1 the split of measurements between different modes and systems is defined. Every second measurement opportunity scheduled for GSM measurements, as given by 8.4.2.1 shall be allocated for GSM initial BSIC identification.
– The remaining measurement opportunities scheduled for GSM measurements shall be scheduled as follows. 3 measurement opportunities out of 4 shall be allocated for GSM carrier RSSI measurements and 1 out of 4 shall be allocated for GSM BSIC reconfirmation. The scheduling of measurement opportunities between GSM carrier RSSI measurements and GSM BSIC reconfirmation is up to the UE.
b) In CELL_FACH state, when signaled by UTRAN and when the UE does not need measurement occasions and idle intervals to perform GSM measurements, the UE shall measure all GSM cells present in the monitored set
– the relevant requirements for GSM dedicated mode when a TCH channel is assigned in [21] shall apply. This is further detailed in the following sub-sections.
8.4.2.5.1 GSM carrier RSSI
a) For a UE using measurement occasions and idle intervals to perform GSM measurements
A UE supporting GSM measurements using measurement occasions and idle intervals shall meet the minimum number of GSM carrier RSSI measurements specified in table 8.7.
In CELL_FACH state the measurement period, Tmeasurement period GSM, for the GSM carrier RSSI measurement is 480 ms.
The UE shall meet the measurement accuracy requirements stated for RXLEV in [21], when the given measurement time allows the UE to take at least 3 GSM carrier RSSI samples per GSM carrier in the monitored set during the measurement period.
Table 8.7
Measurement opportunity length (timeslots) |
Number of GSM carrier RSSI samples per measurement opportunity. |
3 |
1 |
4 |
2 |
5 |
3 |
6 |
4 |
7 |
6 |
8 |
7 |
9 |
8 |
10 |
10 |
11 |
11 |
12 |
12 |
13 |
14 |
15 |
16 |
30 |
32 |
60 |
64 |
120 |
128 |
In case the UE is not able to acquire the required number of samples per GSM carrier during one measurement period, the UE shall measure as many GSM carriers as possible during that measurement period using at least 3 samples per GSM carrier. The GSM carriers that were not measured during that measurement period shall be measured in the following measurement periods. This means that, in this particular case, the L1 reporting period to higher layers of a GSM neighbour can be a multiple of the measurement period.
b) For a UE not using measurement occasions and idle intervals to perform GSM measurements
The samples allocated to each carrier shall as far as possible be uniformly distributed over each measurement period. At least 3 received signal level measurement samples are required per GSM carrier RSSI measurement. The measurement period shall be 480 ms.
In case UTRA RACH procedure prevents the UE from acquiring the required number of samples per GSM carrier during one measurement period, the GSM carriers that were not measured during that measurement period shall be measured in the following measurement periods.
8.4.2.5.2 BSIC verification
a) For a UE using measurement occasions and idle intervals to perform GSM measurements
The procedure for BSIC verification on a GSM cell can be divided into the following two tasks:
1) Initial BSIC identification: Includes searching for the BSIC and decoding the BSIC for the first time when there is no knowledge about the relative timing between the TDD and GSM cell. The requirements for Initial BSIC identification can be found in 8.4.2.5.2.1.
2) BSIC re-confirmation: Tracking and decoding the BSIC of a GSM cell after initial BSIC identification is performed. The requirements for Initial BSIC identification can be found in 8.4.2.5.2.2.
Measurements on a GSM cell can be requested with BSIC verified or BSIC non-verified. If GSM measurements are requested with BSIC verified the UE shall be able to report the GSM cells with BSIC verified for those cells where the verification of BSIC has been successful.
The UE shall consider the BSIC of a GSM cell to be "verified" if it has decoded the SCH of the BCCH carrier and identified the BSIC at least one time (initial BSIC identification) From that time instant, the UE shall attempt to re-confirm the BSIC at least once every 6 times Tre-confirm abort seconds. Otherwise, the UE shall consider the BSIC of the GSM cell to be "non-verified".
The time requirement for initial BSIC identification, Tidentify abort, and the BSIC re-confirmation interval Tre-confirm abort can be found in the sections below.
The UE shall be able to decode a BSIC for the purpose of initial BSIC identification or BSIC reconfirmation within a measurement opportunity, when the time difference between the middle of the received GSM synchronisation burst at the UE and the middle of the measurement opportunity is within the limits specified in Table 8.7.A.
Table 8.7A
Idle Interval Length (timeslots) |
Maximum time difference [s] |
3 |
± 65 |
4 |
± 398 |
5 |
± 732 |
6 |
± 1065 |
7 |
± 1398 |
8 |
± 1732 |
9 |
± 2065 |
10 |
± 2398 |
11 |
± 2732 |
12 |
± 3065 |
13 |
± 3398 |
15 |
± 4100 |
30 |
± 9100 |
60 |
± 19100 |
120 |
± 39100 |
The UE shall be able to perform BSIC verification at levels down to the reference sensitivity level or reference interference levels as specified in [20].
b) For a UE not using measurement occasions and idle intervals to perform GSM measurements
The UE shall attempt to verify the BSIC for at least the 6 strongest GSM carriers at least every 10 seconds, to confirm that it is monitoring the same cell, as far as UTRA RACH procedure does not prevent UE from decoding BSIC.
If a BSIC is decoded and matches the expected value, the UE shall consider it as "verified", otherwise it shall consider it as "non-verified".
The UE shall be able to perform BSIC verification at levels down to the reference sensitivity level or reference interference levels as specified in [20].
8.4.2.5.2.1 Initial BSIC identification
This measurement shall be performed in the measurement opportunities as described in 8.4.2.5.
The UE shall continuously attempt to decode the BSIC of the SCH on the BCCH carrier of the 6 strongest BCCH carriers of the GSM cells indicated in the measurement control information. The UE shall give priority for BSIC decoding attempts in decreasing signal strength order to BSIC carriers with unknown BSIC. The strongest BCCH carrier is defined as the BCCH carrier having the highest measured GSM carrier RSSI value.
When the UE attempts to decode the BSIC of one GSM BCCH carrier with unknown BSIC, the UE shall use all available measurementopportunities allocated for GSM initial BSIC identification according section 8.4.2.5 to attempt to decode the BSIC from that GSM BCCH carrier.
If the BSIC of the GSM BCCH carrier has been successfully decoded the UE shall immediately continue BSIC identification with the next GSM BCCH carrier, in signal strength order, with unknown BSIC. The GSM cell for which the BSIC has been successfully identified shall be moved to the BSIC re-confirmation procedure.
If the UE has not successfully decoded the BSIC of the GSM BCCH carrier within Tidentify abort, the UE shall abort the BSIC identification attempts for that GSM BCCH carrier. The UE shall continue to try to perform BSIC identification of the next GSM BCCH carrier in signal strength order. The GSM BCCH carrier for which the BSIC identification failed shall not be re-considered for BSIC identification until BSIC identification attempts have been made for all the rest of the 6 strongest GSM BCCH carriers in the monitored set with unknown BSIC.
Tidentify abort is specified in section 8.1.2.5.
8.4.2.5.2.2 BSIC re-confirmation
The requirements of this section are applicable for BSIC re-confirmation.
The UE shall maintain the timing information of 6 identified GSM cells. Initial timing information is obtained from the initial BSIC identification. The timing information shall be updated every time the BSIC is decoded.
For each measurement opportunity allocated for GSM BSIC reconfirmation as described in 8.4.2.5, the UE shall attempt to decode the BSIC occurring during the measurement opportunity. When the UE has to select one out of several possible GSM cells to reconfirm during the same measurement opportunity, priority shall be given to the least recently decoded BSIC.
If the UE fails to decode the BSIC after two successive attempts, the UE shall abort the BSIC re-confirmation attempts for that GSM cell. The GSM cell shall be treated as a new GSM cell with unidentified BSIC and the GSM cell shall be moved to the initial BSIC identification procedure, see section 8.4.2.5.2.1. The UE shall be able to make BSIC re-confirmation attempts for the 6 strongest GSM cells in the monitored list.
Where Tre-confirm abort is specified in section 8.1.2.5.