8.4A Measurements in CELL_FACH State (1.28 Mcps option)
25.1233GPPRelease 17Requirements for support of radio resource management (TDD)TS
8.4A.1 Introduction
This section contains requirements on the UE regarding measurement reporting in CELL_FACH state. The requirements for cell re-selection are split in TDD intra frequency, TDD inter frequency, FDD and GSM measurements. The measurements are defined in TS 25.225, the measurement model is defined in TS 25.302 and measurement accuracies are specified in section 9. Control of measurement reporting is specified in TS 25.331 and parallel measurements are specified in section 8.2. For the description of the idle intervals see TS 25.225, Annex A.
NOTE: In CELL_FACH state, there are no requirements for measurements of inter-RAT E-UTRAN cells.
8.4A.2 Requirements
8.4A.2.1 UE Measurement Capability
The UE shall be able to monitor up to
– 32 intra frequency TDD cells, and
– 32 inter frequency cells, including
– TDD cells distributed on up to 8 additional TDD carriers and
– Depending on UE capability, FDD cells, distributed on up to 3 FDD carriers.
– Depending on UE capability, 32 GSM cells distributed on up to 32 GSM carriers.
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 TS 25.331 and, in addition, idle intervals as described in TS 25.225 are used to find and measure on these 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 TS 25.331.
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.
The FACH Measurement Occasion of NTTI frames will be repeated every NTTI * M_REP frame.
8.4A.2.2 TDD intra frequency measurements
During the CELL_FACH state the UE shall continuously measure identified intra frequency cells and search for new intra frequency cells in the monitored set. Intra frequency measurements can be performed (simultaneously to data reception from the active cell) in all time slots not used for inter frequency measurements.
8.4A.2.2.1 Identification of a new cell
The UE shall be able to identify a new detectable cell belonging to the monitored set within
ms
A cell shall be considered detectable when P-CCPCH Ec/Io > -8 dB, DwPCH_Ec/Io > -5 dB.
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.
8.4A.2.2.2 UE P-CCPCH RSCP measurement capability
In the CELL_FACH state the measurement period for intra frequency P-CCPCH RSCP measurements is 200 ms. When all TS0, DwPTS and main guard period in the measurement period are scheduled for intra frequency measurements, the UE shall be capable of performing P-CCPCH RSCP measurements for 6 identified intra-frequency cells of the monitored set and the UE physical layer shall be capable of reporting these measurements to higher layers with the measurement period of 200 ms. When inter-frequency measurements required by the network have to be performed during periods of TS0, DwPTS and main guard period, the UE shall be capable of performing P-CCPCH RSCP measurements for at least Ymeasurement intra cells , where Ymeasurement intra is defined in the following equation.. The measurement accuracy for all measured cells shall be as specified in the section 9. If the UE has identified more than Ymeasurement intra 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.
whereby function Floor(x) takes the integer part of x.
Xbasic measurement TDD is specified in section 8.1A.2.2.2
TMeasurement_Period, Intra is specified in section 8.1A.2.2.2
NPeriod, Intra : is specified in section 8.1A.2.2.2
NIntra : is specified in section 8.1A.2.2.2
Tbasic_identify_TDD, intra is specified in section 8.1A.2.2.2
8.4A.2.2.2A Timeslot ISCP measurement capability
In the CELL_FACH state the measurement period for intra frequency Timeslot ISCP measurements on arbitrary DL timeslots, including Beacon timeslots is 400 ms. When no inter frequency measurement is scheduled, the UE shall be capable of performing Timeslot ISCP measurements on the current serving cell for 5 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.
When inter-frequency measurements are required by the network, the UE shall be able to perform Timeslot ISCP measurements on the current serving for at least Ymeasurement intra ISCP arbitrary DL timeslots, where Ymeasurement intra ISCP is defined in the following equation. Any Timeslot ISCP measurement that could not be performed during that measurement period, shall be measured in the following measurement periods. The measurement accuracy of the Timeslot ISCP measurement shall be as specified in the section 9.
whereby function Floor(x) takes the integer part of x,
Xbasic measurement ISCP = 5 (arbitrary DL timeslots of the current serving cell)
TMeasurement_Period, Intra, ISCP is specified in section 8.1A.2.2.2A,
TIntra is specified in section 8.1A.2.2.2A.
8.4A.2.2.3 RACH Reporting
Reported measurements in the measurement reports sent on the RACH shall meet the requirements in section 9.
8.4A.2.3 TDD inter frequency measurements
When signalled by the network during CELL_FACH state, the UE shall continuously measure identified inter frequency cells and search for new inter frequency cells indicated in the measurement control information.
8.4A.2.3.1 Identification of a new cell
The UE shall be able to identify a new detectable cell belonging to the monitored set within
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.
A cell shall be considered detectable when P-CCPCH Ec/Io > -8 dB, DwPCH_Ec/Io > -5 dB.
8.4A.2.3.2 UE P-CCPCH RSCP measurement capability
When TDD inter frequency measurements are scheduled, the UE physical layer shall be capable of reporting P-CCPCH RSCP measurements to higher layers with measurement accuracy as specified in section 9 with measurement period given by
where
TMeasurement_Period Inter is specified in section 8.1A.2.3.2
N Inter FACH: This is the minimum number of sub-frame in that the signal of P-CCPCH and DwPCH can be received for inter frequency target cell during the period Tmeasurement_Period Inter with an arbitrarily chosen timing. It depends on the channel allocation and on measurement occasions during CELL-FACH state and is calculated by assuming 2*0.1ms for implementation margin (for the description of the idle intervals see Annex A of 25.225 and for definition of measurement occasions during CELL_FACH state given by M_REP and TTI see TS 25.331). During the measurement occasions for CELL_FACH state the UE shall measure primarily cells that can not be measured in the idle intervals.
Tbasic_identify_TDD,inter is specified in section 8.1A.2.3.2
Nbasic identify TDD, Inter is specified in section 8.1A.2.3.2
Tbasic_measurement_TDD inter is specified in section 8.1A.2.3.2
Nbasic measurement TDD, Inter is specified in section 8.1A.2.3.2
NFreq is specified in section 8.1A.2.3.2
If the UE does not need measurement occasions and idle intervals to perform inter-frequency measurements, the measurement period for inter frequency measurements is 480ms.
The UE shall be capable of performing P-CCPCH measurements for Xbasic measurement TDD inter inter-frequency cells per TDD 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_ Inter.
Xbasic measurement TDDinter is defined in section 8.1A.2.3.2.
8.4A.2.4 FDD measurements
The requirements in this section shall apply only to UE supporting 1.28Mcps TDD and FDD.
In the CELL_FACH state when FDD inter frequency measurements are scheduled the UE shall continuously measure identified inter frequency FDD cells and search for new inter frequency FDD cells indicated in the measurement control information.
8.4A.2.4.1 Identification of a new cell
The UE shall be able to identify a new detectable 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 TDD cell belonging to the monitored set within 5000ms.
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.
8.4A.2.4.2 UE CPICH measurement capability
When FDD inter frequency measurements are scheduled, 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
TMeasurement_Period FDD inter is specified in section 8.1A.2.4.2
T Inter FACH: This is the minimum time that is available for the inter frequency measurements during the period TMeasurement_Period FDD inter with an arbitrarily chosen timing. The minimum time depends on the channel allocation and on measurement occasions during CELL_FACH state and is calculated by assuming 2*0.1 ms for implementation margin (for the description of the idle intervals see Annex A of 25.225 and for definition of measurement occasions during CELL_FACH state given by M_REP and TTI see TS 25.331). It is assumed for the requirement that the slot allocation allows measurement windows in the idle periods to be of minimum duration necessary to perform the measurements. During the measurement occasions for CELL_FACH state the UE shall measure primarily cells that can not be measured in the idle intervals.
Tbasic_identify_FDD,inter is specified in section 8.1A.2.4.2
Tbasic_measurement_FDD inter is specified in section 8.1A.2.4.2.
NFreq is specified in section 8.1A.2.4.2
If the UE does not need measurement occasions and idle intervals to perform inter-frequency measurements, the measurement period for FDD measurements is 480 ms.
The UE shall be capable of performing CPICH measurements for Xbasic measurement FDD inter inter-frequency cells per FDD frequency of the monitored set, and the UE physical layer shall be capable of reporting measurements to higher layers with the measurement period of TMeasurementFDD Inter.
Xbasic measurement FDDinter is defined in section 8.1A.2.4.2
8.4A.2.5 GSM measurements
The requirements in this section shall apply to UE supporting 1.28Mcps TDD and GSM.
To support cell reselection the UE shall always perform BSIC verification in Cell FACH state.
1) For a UE requiring idle intervals or measurement occasions to perform GSM measurements.When signalled by UTRAN during CELL_FACH state, the UE shall continuously measure GSM cells and search for new GSM cells given in the monitored set.
In section 8.4A.2.1 the split of measurements between different modes and systems is defined. Every second measurement window due to idle intervals and measurements occasions scheduled for GSM measurements, as given by 8.4A.2.1 shall be allocated for GSM initial BSIC identification.
The remaining measurement windows due to idle intervals and measurements occasions used for GSM measurements shall be scheduled as follows. 3 window 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 windows between GSM carrier RSSI measurements and GSM BSIC reconfirmation is up to the UE.
2) For a UE not requiring idle intervals and measurement occasions 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 TS 45.008 shall apply. This is further detailed in the following sub-sections.
8.4A.2.5.1 GSM carrier RSSI
1) For a UE requiring idle intervals or measurement occasions to perform GSM measurements.
An UE supporting GSM measurements shall meet the minimum number of GSM carrier RSSI measurements specified in table 8.8. This measurement shall be based on measurement windows allocated for GSM carrier RSSI measurements as described in 8.4A.2.5. In the CELL_FACH state the measurement period for the GSM carrier RSSI measurement is 480 ms.
The UE shall meet the measurement accuracy requirements stated for RXLEV in TS 45.008, 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 8.8
Measurement Window Length (slots) |
Number of GSM carrier RSSI samples per measurement window |
3 |
1 |
4 |
2 |
5 |
3 |
7 |
6 |
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.
2) For a UE not requiring idle intervals and measurement occasions 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 RSSI value. The measurement period is 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.
8.4A.2.5.2 BSIC verification
1) For a UE requiring idle intervals or measurement occasions to perform GSM measurements.
The procedure for BSIC verification on a GSM cell can be divided into the following two tasks:
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 UE shall trigger the initial BSIC identification within 50% of the available measurement windows. The requirements for Initial BSIC identification can be found in 8.4A.2.5.2.1,Initial BSIC identification
BSIC re-confirmation
Tracking and decoding the BSIC of a GSM cell after initial BSIC identification is performed. The UE shall trigger the BSIC re-confirmation within the available measurement windows. The requirements for BSIC re-confirmation can be found in section 8.4A.2.5.2.2, BSIC re-confirmation.
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 BSIC of a GSM cell is considered to be "verified" if the UE has decoded the SCH of the BCCH carrier and identified the BSIC at least one time (initial BSIC identification) and from that moment the BSIC shall be re-confirmed at least once every 6 times Tre-confirm abort seconds. Otherwise the BSIC of the GSM cell is considered as "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 perform BSIC verification at levels down to the reference sensitivity level or reference interference levels as specified in TS 45.005.
2) For a UE not requiring idle intervals and measurement occasions to perform GSM measurements:
The UE shall attempt to check 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, it is considered as "verified", else it is considered 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 TS 45.005.
8.4A.2.5.2.1 Initial BSIC identification
This measurement is performed in the measurement windows allocated for Initial BSIC identification as described in 8.4A.2.5.
For GSM cells that are requested with BSIC verified the UE shall continuously attempt to decode 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 measurements windows allocated for GSM initial BSIC identification according section 8.4A.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 8.1A.2.5.
8.4A.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 window allocated for GSM BSIC reconfirmation as described in 8.4A.2.5, the UE shall attempt to decode the BSIC falling within the effective measurement window duration. If more than one BSIC can be decoded within the same measurement window, 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 8.4A.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.
Tre-confirm abort is specified in section 8.1A.2.5.
It is assumed for the requirement that the measurement windows possible due to higher layer parameters are of minimum duration necessary to perform the measurements.