8 Radio link measurements

05.083GPPRadio subsystem link controlTS

Radio link measurements are used in the handover and RF power control processes.

In particular, radio‑subsystem directed handover is defined as a change of channel(s) during a call either because of degradation of the quality of one or more of the current serving channel(s), or because of the availability of other channel(s) which can allow communication at a lower TX power level, or to prevent a MS grossly exceeding the planned cell boundaries.

Additional measurements, so called Extended measurements, can e.g. be used for frequency planning purposes.

The measurements are made over each SACCH multiframe, which is 104 TDMA frames (480 ms) for a TCH and 102 TDMA frames (470,8 ms) for an SDCCH. Additionally, when in E-TCH mode, quality measurements shall also be made over each FPC reporting period.

For a multi-RAT MS, measurements on other radio access technologies may be performed during search frames that are not required for BSIC decoding. If indicated by the parameter 3G_SEARCH_PRIO, the MS may use up to 25 search frames per 13 seconds without considering the need for BSIC decoding in these frames.

8.1 Signal level

8.1.1 General

The received signal level may be employed as a criterion in the RF power control and handover processes. For cells of other radio access technology, RXLEV is replaced by the relevant measurement quantity for that radio access technology (see subclause 8.1.5).

8.1.2 Physical parameter

The R.M.S received signal level at the receiver input shall be measured by the MS and the BSS over the full range of ‑110 dBm to ‑48 dBm with an absolute accuracy of ±4 dB from ‑110 dBm to ‑70 dBm under normal conditions and ±6 dB over the full range under both normal and extreme conditions. The R.M.S received signal level at the receiver input shall be measured by the MS above -48 dBm up to -38 dBm with an absolute accuracy of ± 9 dB under both normal and extreme conditions.

If the received signal level falls below the reference sensitivity level for the type of MS or BSS, then the measured level shall be within the range allowing for the absolute accuracy specified above. In case the upper limit of this range is below the reference sensitivity level for the type of MS or BSS, then the upper limit shall be considered as equal to the reference sensitivity level.

The relative accuracy shall be as follows:

If signals of level x1 and x2 dBm are received (where x1  x2) and levels y1 and y2 dBm respectively are measured, if x2 ‑ x1 < 20 dB and x1 is not below the reference sensitivity level, then y1 and y2 shall be such that:

(x2 ‑ x1) ‑ a  y2 ‑ y1  (x2 ‑ x1 + b) if the measurements are on the same or on different RF channel within the same frequency band;

and

(x2 ‑ x1 ) ‑ c  y2 ‑ y1 ( x2 ‑ x1 + d) if the measurements are on different frequency bands:

a, b, c and d are in dB and depend on the value of x1 as follows:

a

b

c

d

x1  s+14, x2< -48 dBm

2

2

4

4

s+14 > x1  s+1

3

2

5

4

s+1 > x1

4

2

6

4

For single band MS or BTS and measurements between ARFCN in the same band for a multiband

MS or BTS;

s = reference sensitivity level as specified in 3GPP TS 05.05.

For measurements between ARFCN in different bands;

s = the reference sensitivity level as specified in 3GPP TS 05.05 for the band including x1.

At extreme temperature conditions an extra 2 dB shall be added to c and d in above table.

The selectivity of the received signal level measurement shall be as follows:

‑ for adjacent (200 kHz) channel  16 dB;

‑ for adjacent (400 kHz) channel  48 dB;

‑ for adjacent (600 kHz) channel  56 dB.

The selectivity shall be met using random, continuous, GSM‑modulated signals with the wanted signal at the level 20 dB above the reference sensitivity level.

8.1.3 Statistical parameters

For each channel, the measured parameters (RXLEV) shall be the average of the received signal level measurement samples in dBm taken on that channel within the reporting period of length one SACCH multiframe defined in 8.4. In averaging, measurements made during previous reporting periods shall always be discarded.

When assigned a TCH or SDCCH the MS shall make a received signal level measurement:

‑ in every TDMA frame on at least one of the BCCH carriers indicated in the BCCH allocation (BA), one after another. Optionally, measurements during up to 8 frames per SACCH multiframe may be omitted;

As an exception, a multi-RAT MS may omit GSM measurements during up to 9 TDMA frames per SACCH multiframe and use these periods for measurements on other radio access technologies.
Furthermore, an MS on SDCCH is allowed schedule the measurements freely within the SACCH multiframe as long as the total number of measurement samples is maintained and the samples on each carrier are evenly spaced.

NOTE: These eight frames are the search frames and the frames immediately preceding the search frames, in order to allow the MS to search for BCCH synchronization (or inter-RAT measurements) over a full TDMA frame.

‑ for each assigned bi‑directional channel, on all bursts of the associated physical channel (see 3GPP TS 05.02), including those of the SACCH. If frequency hopping is being used on the associated physical channel and if, in the BCCH Cell Options, the Power Control Indicator PWRC is set, measurements on the bursts on the BCCH frequency shall not be used in the RXLEV averaging process.

Unless otherwise specified by the operator, for any TCH or SDCCH assigned to an MS, the BSS shall make a received signal level measurement on all time slots of the associated physical channel including those of the SACCH, but excluding the idle timeslots.

8.1.4 Range of parameter

The measured signal level shall be mapped to an RXLEV value between 0 and 63, as follows:

RXLEV 0 = less than ‑110 dBm + SCALE.
RXLEV 1 = ‑110 dBm + SCALE to ‑109 dBm + SCALE.
RXLEV 2 = ‑109 dBm + SCALE to ‑108 dBm + SCALE.
:
:
RXLEV 62 = ‑49 dBm + SCALE to ‑48 dBm + SCALE.
RXLEV 63 = greater than ‑48 dBm + SCALE.

where SCALE is an offset that is used only in the ENHANCED MEASUREMENT REPORT message, otherwise it is set to 0.

The MS shall use the SCALE value as indicated by the parameter SCALE_ORD in the MEASUREMENT INFORMATION message (see 3GPP TS 04.18 and 3GPP TS 04.60). If automatic scaling mode is indicated by SCALE_ORD, the MS shall choose the lowest SCALE value that is sufficient for reporting the strongest signal level within each ENHANCED MEASUREMENT REPORT message.

The MS shall indicate the used SCALE value in each individual ENHANCED MEASUREMENT REPORT message (see 3GPP TS 04.18).

8.1.5 Measurement quantity for other radio access technologies

8.1.5.1 UTRAN FDD

For UTRAN FDD cells, the measurement quantities to be used are CPICH Ec/No and CPICH RSCP and RSSI. The measurement requirements are defined in TS 25.133.

RSCP shall be used for the cell re-selection ranking criteria. Ec/No, and optionally RSCP, shall be used for a minimum quality requirement. Either RSCP or Ec/No shall be used for measurement reporting as indicated by the parameter FDD_REP_QUANT, sent on BCCH, SACCH, PBCCH and PACCH. In addition, if a frequency without scrambling code is included in the neighbour cell list, RSSI shall be reported for that frequency.

The measured value shall replace RXLEV in the measurement reports. The mapping is defined in TS 25.133. For RSCP and RSSI, values above 63 shall be reported as 63. For Ec/No, the full value range is not used.

8.1.5.2 UTRAN TDD

For UTRAN TDD cells, the measurement quantity to be used is PCCPCH RSCP. The measurement requirements are defined in TS 25.123.

NOTE: The RSCP may alternatively be measured on any beacon channel (see 3GPP TS 25.221).

The measured value shall replace RXLEV in the measurement reports. The mapping is defined in TS 25.123. For RSCP, values above 63 shall be reported as 63.

8.1.5.3 cdma2000

For cdma2000 cells, the measurement quantity to be used is PILOT_STRENGTH of the pilot. The measurement requirements are defined in TIA/EIA/IS-2000-5-A.

The measured value shall replace RXLEV in the measurement reports.

8.2 Signal quality

8.2.1 General

The received signal quality shall be employed as a criterion in the RF power control and handover processes.

8.2.2 Physical parameter

The received signal quality shall be measured by the MS and BSS in a manner that can be related to an equivalent average BER before channel decoding (i.e. chip error ratio), assessed over the reporting period of 1 SACCH block.

For FPC, the received signal quality for each E-TCH shall be measured by the MS and BSS in a manner that can be related to the average BER before channel decoding, assessed over one FPC reporting period.

For example, the measurement may be made as part of the channel equalization process, decoding process, pseudo‑error rate measurement etc.

For MEAN_BEP and CV_BEP reporting purposes, the received signal quality for each channel shall be measured on a burst-by-burst basis by the MS and BSS in a manner that can be related to the BEP (Bit Error Probability) for each burst before channel decoding using, for example, soft output from the receiver.

8.2.3 Statistical parameters

For each channel, the measured parameters (RXQUAL) shall be the received signal quality, averaged on that channel over the reporting period of length one SACCH multiframe defined in subclause 8.4. In averaging, measurements made during previous reporting periods shall always be discarded.

Contrary to RXLEV measurements, in calculating RXQUAL values, measurements on bursts on the BCCH carrier shall always be included in the averaging process.

For E-TCH the average BER shall for every FPC reporting period be mapped to the RXQUAL scale according to chapter 8.2.4, producing the parameter RXQUAL_FAST which is reported to the network via E-IACCH.

For TCH, E-TCH, SDCCH, SACCH and FACCH, the MS shall calculate the following values for the last 4 consecutive slots of each fully received and correctly decoded block (see subclause 8.4.8.2):

  • Mean Bit Error Probability (BEP) of the block:
  • Coefficient of variation of the Bit Error Probability of the block:

Note: The receiver needs to detect if a block has been fully received (i.e. estimate whether it was fully transmitted) when DTX is used because a block may be correctly decoded even if the last 4 slots were actually not transmitted, especially in the case of 19 interleaving.

The calculated values shall be averaged (on a linear scale) over the reporting period as follows:

MEAN_BEP = average of MEAN_BEPblock.

CV_BEP = average of CV_BEPblock.

In averaging, measurements made during previous reporting periods shall always be discarded.

For EGPRS, the MS shall calculate the following values for each radio block (4 bursts) addressed to it:

  • Mean Bit Error Probability (BEP) of a radio block:
  • Coefficient of variation of the Bit Error Probability of a radio block:

Filtering and reporting are described in subclause 10.2.3.2.

8.2.4 Range of parameter RXQUAL

When the quality is assessed over the full‑set and sub‑set of frames defined in subclause 8.4, eight levels of RXQUAL are defined and shall be mapped to the equivalent BER before channel decoding as follows:

RXQUAL_0 BER < 0,2 % Assumed value = 0,14 %
RXQUAL_1 0,2 % < BER < 0,4 % Assumed value = 0,28 %
RXQUAL_2 0,4 % < BER < 0,8 % Assumed value = 0,57 %
RXQUAL_3 0,8 % < BER < 1,6 % Assumed value = 1,13 %
RXQUAL_4 1,6 % < BER < 3,2 % Assumed value = 2,26 %
RXQUAL_5 3,2 % < BER < 6,4 % Assumed value = 4,53 %
RXQUAL_6 6,4 % < BER < 12,8 % Assumed value = 9,05 %
RXQUAL_7 12,8 % < BER Assumed value = 18,10 %

The assumed values may be employed in any averaging process applied to RXQUAL.

The same mapping table applies also for RXQUAL_FAST.

The BER values used to define a quality band are the estimated error probabilities before channel decoding, averaged over the full set or sub set of TDMA frames as defined in subclause 8.4. The accuracy to which an MS shall be capable of estimating the error probabilities when on a TCH under static channel conditions is given in the following table. Note the exception of subclause 8.4 on data channels using interleaving depth 19 and on half rate speech channel.

Quality Band

Range of actual BER

Probability that the correct RXQUAL

band is reported by MS shall exceed

Full rate Channel

Half rate Channel

DTX Mode

ECSD FPC mode

RXQUAL_0

Less than 0,1 %

90 %

90 %

65 %

70 %

RXQUAL_1

0,26 % to 0,30 %

75 %

60 %

35 %

60 %

RXQUAL_2

0,51 % to 0,64 %

85 %

70 %

45 %

60 %

RXQUAL_3

1,0 % to 1,3 %

90 %

85 %

45 %

60 %

RXQUAL_4

1,9 % to 2,7 %

90 %

85 %

60 %

60 %

RXQUAL_5

3,8 % to 5,4 %

95 %

95 %

70 %

90 %

RXQUAL_6

7,6 % to 11,0 %

95 %

95 %

80 %

90 %

RXQUAL_7

Greater than 15,0 %

95 %

95 %

85 %

90 %

NOTE 1: For the full rate channel RXQUAL_FULL is based on 104 TDMA frames.

NOTE 2: For the half rate channel RXQUAL_FULL is based on 52 TDMA frames.

NOTE 3: For the DTX mode RXQUAL_SUB is based on 12 TDMA frames.

NOTE 4: For the ECSD FPC mode RXQUAL_FAST is based on 4 TDMA frames.

The accuracy to which an MS shall be capable of estimating the error probabilities when on a TCH under TU50 channel conditions is given in the following table. Note the exception of subclause 8.4 on data channels using interleaving depth 19 and on half rate speech channel.

Range of actual BER

Expected RXQUAL_FULL

Probability that expected RXQUAL_FULL is reported shall exceed

Less than 0,1 %

RXQUAL_0/1

85 %

0,26 % to 0,30 %

RXQUAL_1/0/2

85 %

0,51 % to 0,64 %

RXQUAL_2/1/3

85 %

1,0 % to 1,3 %

RXQUAL_3/2/4

75 %

1,9 % to 2,7 %

RXQUAL_4/3/5

75 %

3,8 % to 5,4 %

RXQUAL_5/4/6

90 %

7,6 % to 11,0 %

RXQUAL_6/5/7

90 %

Greater than 15,0 %

RXQUAL_7/6

90 %

It should be noted that in the testing, the System Simulator (SS) or (BSSTE) Base Station System Test Equipment will have to measure the average error rate over a large number of TDMA frames.

8.2.5 Range of parameters MEAN_BEP and CV_BEP

The mapping of the MEAN_BEP to the equivalent BEP and the accuracies to which an MS shall be capable of estimating the quality parameters under static channel conditions are given in the following tables for GMSK and 8-PSK respectively. The accuracy requirements below apply for EGPRS for sensitivity limited operation for signal levels above the reference sensitivity level for the type of MS. Filtering according to subclause 10.2.3.2.1 with forgetting factor of 0.03 is assumed.

MEAN_BEP mapping and accuracy for GMSK

MEAN_BEP

Range of
log10(actual BEP)

Expected MEAN_BEP
interval

Probability that the expected MEAN_BEP is reported shall not be

lower than:

MEAN_BEP_0

> -0.60

MEAN_BEP_0/1

80 %

MEAN_BEP_1

-0.70 — -0.60

MEAN_BEP_1/0/2

80 %

MEAN_BEP_2

-0.80 — -0.70

MEAN_BEP_2/1/3

75 %

MEAN_BEP_3

-0.90 — -0.80

MEAN_BEP_3/2/4

75 %

MEAN_BEP_4

-1.00 — -0.90

MEAN_BEP_4/3/5

75 %

MEAN_BEP_5

-1.10 — -1.00

MEAN_BEP_5/4/6

75 %

MEAN_BEP_6

-1.20 — -1.10

MEAN_BEP_6/5/7

75 %

MEAN_BEP_7

-1.30 — -1.20

MEAN_BEP_7/6/8

75 %

MEAN_BEP_8

-1.40 — -1.30

MEAN_BEP_8/7/9

75 %

MEAN_BEP_9

-1.50 — -1.40

MEAN_BEP_9/8/10

75 %

MEAN_BEP_10

-1.60 — -1.50

MEAN_BEP_10/9/11

70 %

MEAN_BEP_11

-1.70 — -1.60

MEAN_BEP_11/10/12

70 %

MEAN_BEP_12

-1.80 — -1.70

MEAN_BEP_12/11/13

70 %

MEAN_BEP_13

-1.90 — -1.80

MEAN_BEP_13/12/14

70 %

MEAN_BEP_14

-2.00 — -1.90

MEAN_BEP_14/13/15

70 %

MEAN_BEP_15

-2.10 — -2.00

MEAN_BEP_15/13/14/16/17

80 %

MEAN_BEP_16

-2.20 — -2.10

MEAN_BEP_16/14/15/17/18

80 %

MEAN_BEP_17

-2.30 — -2.20

MEAN_BEP_17/15/16/18/19

80 %

MEAN_BEP_18

-2.40 — -2.30

MEAN_BEP_18/16/17/19/20

80 %

MEAN_BEP_19

-2.50 — -2.40

MEAN_BEP_19/17/18/20/21

80 %

MEAN_BEP_20

-2.60 — -2.50

MEAN_BEP_20/18/19/21/22

80 %

MEAN_BEP_21

-2.70 — -2.60

MEAN_BEP_21/19/20/22/23

80 %

MEAN_BEP_22

-2.80 — -2.70

MEAN_BEP_22/20/21/23/24

80 %

MEAN_BEP_23

-2.90 — -2.80

MEAN_BEP_23/21/22/24/25

80 %

MEAN_BEP_24

-3.00 — -2.90

MEAN_BEP_24/22/23/25/26

80 %

MEAN_BEP_25

-3.10 — -3.00

MEAN_BEP_25/22/23/24/26/27/28

75 %

MEAN_BEP_26

-3.20 — -3.10

MEAN_BEP_26/23/24/25/27/28/29

75 %

MEAN_BEP_27

-3.30 — -3.20

MEAN_BEP_27/24/25/26/28/29/30

75 %

MEAN_BEP_28

-3.40 — -3.30

MEAN_BEP_28/25/26/27/29/30/31

75 %

MEAN_BEP_29

-3.50 — -3.40

MEAN_BEP_29/26/27/28/30/31

90 %

MEAN_BEP_30

-3.60 — -3.50

MEAN_BEP_30/27/28/29/31

90 %

MEAN_BEP_31

< -3.60

MEAN_BEP_31/28/29/30

90 %

MEAN_BEP mapping and accuracy for 8PSK

MEAN_BEP

Range of
log10(actual BEP)

Expected MEAN_BEP
interval

Probability that the expected MEAN_BEP is reported shall not be lower than:

MEAN_BEP_0

> -0.60

MEAN_BEP_0/1/2

85 %

MEAN_BEP_1

-0.64 — -0.60

MEAN_BEP_1/0/2/3

85 %

MEAN_BEP_2

-0.68 — -0.64

MEAN_BEP_2/0/1/3/4

85 %

MEAN_BEP_3

-0.72 — -0.68

MEAN_BEP_3/1/2/4/5

85 %

MEAN_BEP_4

-0.76 — -0.72

MEAN_BEP_4/2/3/5/6

85 %

MEAN_BEP_5

-0.80 — -0.76

MEAN_BEP_5/3/4/6/7

85 %

MEAN_BEP_6

-0.84 — -0.80

MEAN_BEP_6/4/5/7/8

85 %

MEAN_BEP_7

-0.88 — -0.84

MEAN_BEP_7/5/6/8/9

85 %

MEAN_BEP_8

-0.92 — -0.88

MEAN_BEP_8/6/7/9/10

80 %

MEAN_BEP_9

-0.96 — -0.92

MEAN_BEP_9/7/8/10/11

80 %

MEAN_BEP_10

-1.00 — -0.96

MEAN_BEP_10/8/9/11/12

80 %

MEAN_BEP_11

-1.04 — -1.00

MEAN_BEP_11/9/10/12/13

80 %

MEAN_BEP_12

-1.08 — -1.04

MEAN_BEP_12/10/11/13/14

80 %

MEAN_BEP_13

-1.12 — -1.08

MEAN_BEP_13/11/12/14/15

80 %

MEAN_BEP_14

-1.16 — -1.12

MEAN_BEP_14/12/13/15/16

85 %

MEAN_BEP_15

-1.20 — -1.16

MEAN_BEP_15/13/14/16

85 %

MEAN_BEP_16

-1.36 — -1.20

MEAN_BEP_16/14/15/17

85 %

MEAN_BEP_17

-1.52 — -1.36

MEAN_BEP_17/16/18

95 %

MEAN_BEP_18

-1.68 — -1.52

MEAN_BEP_18/17/19

95 %

MEAN_BEP_19

-1.84 — -1.68

MEAN_BEP_19/18/20

95 %

MEAN_BEP_20

-2.00 — -1.84

MEAN_BEP_20/19/21

95 %

MEAN_BEP_21

-2.16 — -2.00

MEAN_BEP_21/20/22

85 %

MEAN_BEP_22

-2.32 — -2.16

MEAN_BEP_22/21/23

85 %

MEAN_BEP_23

-2.48 — -2.32

MEAN_BEP_23/22/24

85 %

MEAN_BEP_24

-2.64 — -2.48

MEAN_BEP_24/23/25

85 %

MEAN_BEP_25

-2.80 — -2.64

MEAN_BEP_25/23/24/26/27

85 %

MEAN_BEP_26

-2.96 — -2.80

MEAN_BEP_26/24/25/27/28

85 %

MEAN_BEP_27

-3.12 — -2.96

MEAN_BEP_27/25/26/28/29

80 %

MEAN_BEP_28

-3.28 — -3.12

MEAN_BEP_28/26/27/29/30

80 %

MEAN_BEP_29

-3.44 — -3.28

MEAN_BEP_29/27/28/30/31

80 %

MEAN_BEP_30

-3.60 — -3.44

MEAN_BEP_30/28/29/31

90 %

MEAN_BEP_31

< -3.60

MEAN_BEP_31/29/30

90 %

For a coding on 4 bits, the 4 most significant bits are used.

NOTE1: MEAN_BEP is calculated and filtered in a linear scale but mapped to a logarithmic scale for reporting.

NOTE2: The accuracy requirements above take into account possible fluctuations of the bit error rate due to adaptiveness of receivers.

NOTE3: Testing requires measurement of the actual bit error rate and assessment of MEAN_BEP reports based on the same period of time.

The mapping table for the coefficient of variation of the channel quality is defined as follows for both 8-PSK and GMSK:

CV_BEP 0

2.00

> CV_BEP >

1.75

CV_BEP 1

1.75

> CV_BEP >

1.50

CV_BEP 2

1.50

> CV_BEP >

1.25

CV_BEP 3

1.25

> CV_BEP >

1.00

CV_BEP 4

1.00

> CV_BEP >

0.75

CV_BEP 5

0.75

> CV_BEP >

0.50

CV_BEP 6

0.50

> CV_BEP >

0.25

CV_BEP 7

0.25

> CV_BEP >

0.00

The accuracy requirements for CV_BEP need not be specified since they are directly linked to those for MEAN_BEP. Nevertheless, the CV_BEP measured at the MS shall be the one used by this MS.

8.3 Aspects of discontinuous transmission (DTX)

When DTX is employed on a TCH, not all TDMA frames may be transmitted. However, the following subset shall always be transmitted, except for TCH/AFS and TCH/AHS, and hence can be employed to assess quality and signal level during DTX.

Type of channel

TDMA frame subset always to be transmitted

TDMA frame number (FN) modulo 104

TCH/F

52, 53, 54, 55, 56, 57, 58, 59

TCH/HS,subchannel 0

0, 2, 4, 6, 52, 54, 56, 58

TCH/HS,subchannel 1

14, 16, 18, 20, 66, 68, 70, 72

TCH/H,data,subchannel 0,uplink

52, 54, 56, 58, 60, 62, 65, 67, 69, 71

TCH/H,data,subchannel 0,downlink

56, 58, 60, 62, 65, 67, 69, 71, 73, 75

TCH/H,data,subchannel 1,uplink

70, 72, 74, 76, 79, 81, 83, 85, 87, 89

TCH/H,data,subchannel 1,downlink

66, 68, 70, 72, 74, 76, 79, 81, 83, 85

On any TCH this subset of TDMA frames is always used for transmission during DTX. For speech, when no signalling or speech is to be transmitted these TDMA frames are occupied by the SID (Silence Descriptor) frame, see 3GPP TS 06.12 and TSM 3GPP TS 06.31 for detailed specification of the SID frame and its transmission requirements. In other cases when no information is required to be transmitted, e.g. on data channels, the L2 fill frame (see 3GPP TS 04.06 subclause 5.4.2.3) shall be transmitted as a FACCH in the TDMA frame subset always to be transmitted.

On the SDCCH and on the half rate traffic channel TCH/H in signalling only mode DTX is not allowed. In these cases and on the TCH/F in signalling only mode when DTX is not used, the same L2 fill frame shall be transmitted in case there is nothing else to transmit.

On TCH/AFS and TCH/AHS, there is no fixed subset of TDMA frames that will always be transmitted during DTX. A detection algorithm is required in the receiver which informs about whether a SID_UPDATE (see 3GPP TS 05.03 and 3GPP TS 06.93) frame was transmitted (and thus can be used for quality and signal level estimation) or not.

If no FPC commands are received during a reporting period, the SACCH power command shall be used.

8.4 Measurement reporting

8.4.1 Measurement reporting for the MS on a TCH

For a TCH, the reporting period of length 104 TDMA frames (480 ms) is defined in terms of TDMA frame numbers (FN) as follows:

Timeslot number (TN)

TDMA frame number (FN) modulo 104

TCH/F

TCH/H,subch.0

TCH/H,subch.1

Reporting period

SACCH Message block

0

0 and 1

0 to 103

12, 38, 64, 90

1

0 and 1

13 to 12

25, 51, 77, 103

2

2 and 3

26 to 25

38, 64, 90, 12

3

2 and 3

39 to 38

51, 77, 103, 25

4

4 and 5

52 to 51

64, 90, 12, 38

5

4 and 5

65 to 64

77, 103, 25, 51

6

6 and 7

78 to 77

90, 12, 38, 64

7

6 and 7

91 to 90

103, 25, 51, 77

For a multislot configuration, the reporting period and SACCH Message block for each timeslot is defined as for TCH/F for TN = 0.

When on a TCH, the MS shall assess during the reporting period and transmit to the BSS in the next SACCH message block the following:

‑ RXLEV for the BCCH carrier of the 6 cells with the highest RXLEV among those with known and allowed NCC part of BSIC. For a multi band MS the number of cells, for each frequency band supported, which shall be included is specified in subclause 8.4.3. For a cell of other radio access technology, see subclauses 8.1.5 and 8.4.7.

NOTE 1: Since there are 104 TDMA frames in each SACCH multiframe (and measurement in 4 frames is optional), the number of samples on each BCCH carrier will depend on the number of carriers defined in the BCCH Allocation (BA) and may be different. The following table gives examples of this.

Number of BCCH carriers

Number of samples per

in BCCH Allocation

carrier in SACCH multiframe

32

3‑4

16

6‑7

10

10‑11

8

12‑13

:

:

:

:

These figures are increased if the MS is able to make measurements on more than one BCCH carrier during each TDMA frame.

‑ RXLEV_FULL and RXQUAL_FULL: RXLEV and RXQUAL for the full set of TCH and SACCH TDMA frames. The full set of TDMA frames is either 100 (i.e. 104 ‑ 4 idle) frames for a full rate TCH or 52 frames for a half‑rate TCH.

‑ RXLEV_SUB and RXQUAL_SUB: RXLEV and RXQUAL for the subset of 4 SACCH frames and the SID TDMA frames/ SID_UPDATE frames/L2 fill frames defined in 8.3. In case of data traffic channels TCH/F9.6, TCH/F4.8, TCH/H4.8 and TCH/H2.4, the RXQUAL_SUB report shall include measurements on the TDMA frames given in the table of subclause 8.3 only if L2 fill frames have been received as FACCH frames at the corresponding frame positions. If no FACCH frames have been received at the corresponding frame positions, the RXQUAL_SUB report shall include measurements on the 4 SACCH frames only. The performance requirements of subclause 8.2.4 do not apply in this case for RXQUAL_SUB.

In case of half rate speech channel TCH/HS, if a SID frame or a speech frame as defined in subclause 8.3 is replaced by an FACCH frame, the RXQUAL measurement on these frames shall be excluded from the RXQUAL SUB report. The performance requirements of subclause 8.2.4 do not apply in this case for RXQUAL SUB.

In case of half rate traffic channel TCH/H in signalling only mode, -SUB values are set equal to the -FULL values in the SACCH message, since DTX is not allowed in this case.

In the case of TCH/AFS or TCH/AHS, the RXLEV_SUB and RXQUAL_SUB shall take into account all detected SID_UPDATE frames in addition to the 4 SACCH frames.

NOTE 2: If measurement on the BCCH carrier is not used, the number of TDMA frames used in the RXLEV averaging process may be lower than the number of TDMA frames in the set see subclause 8.1.3.

In case of a multislot configuration, the MS shall report the following according to the definition above:

‑ on the main SACCH: the RXLEV values from the adjacent cells, RXLEV_FULL and RXLEV_SUB from the main channel and the worst RXQUAL_FULL values and RXQUAL_SUB values from the main channel and the unidirectional channels;

‑ on each other bi‑directional SACCH: the RXLEV values from the adjacent cells, RXLEV_FULL, RXLEV_SUB, RXQUAL_FULL and RXQUAL_SUB from the corresponding channel.

8.4.1.1 Measurement reporting for the MS on an E-TCH in FPC mode

For an E-TCH, the FPC reporting period of length 4 TDMA frames (20 ms) is defined according to chapter 4.7,

When on an E-TCH using 8PSK for the uplink, the MS shall, in addition to what is specified in chapter 8.4.1, assess during the FPC reporting period and transmit to the BSS in the next scheduled FPC inband message (see chapter 4.7) the following:

  • RXQUAL_FAST: RXQUAL for the set of 4 TDMA frames.

8.4.2 Measurement reporting for the MS on a SDCCH

For a SDCCH, the reporting period of length 102 TDMA frames (470.8 ms) is defined in terms of TDMA frame numbers (FN) as follows:

TDMA frame number

(FN) modulo 102

SDCCH/8

12 to 11

SDCCH/4

37 to 36

NOTE 1: Some SDCCH data or TCH speech, data or SID message blocks are spread over two reporting periods. In these cases, the RXLEV and/or RXQUAL information from the SDCCH or TCH message blocks may either be sent as part of the measurement report of the second period, or shared between the reports of the two periods.

When on a SDCCH, the MS shall assess during the reporting period and transmit to the BSS in the next SACCH message block the following:

‑ RXLEV for the BCCH carrier of the 6 cells with the highest RXLEV among those with known and allowed NCC part of BSIC. For a multi band MS the number of cells, for each frequency band supported, which shall be included is specified in subclause 8.4.3. For a cell of other radio access technology, see subclauses 8.1.5 and 8.4.7.

NOTE 2: With only 102 TDMA frames in each SACCH multiframe, the number of samples used to calculate RXLEV per BCCH carrier may be slightly different from the case of TCH described above.

‑ RXLEV and RXQUAL for the full set of 12 (8 SDCCH and 4 SACCH) frames within the reporting period. As DTX is not allowed on the SDCCH, ‑SUB values are set equal to the ‑FULL values in the SACCH message.

NOTE 3: If measurement on the BCCH carrier is not used, the number of TDMA frames used in the RXLEV averaging process may be lower than the number of TDMA frames in the full set see subclause 8.1.3.

8.4.3 Additional cell reporting requirements for multi band MS

For a multi band MS the number of cells, for each frequency band supported, which shall be included in the measurement report is indicated by the parameter MULTIBAND_REPORTING, broadcast on BCCH and PBCCH. An MS attached to GPRS shall use the parameter broadcast on PBCCH if it exists. In all other cases, the MS shall use the parameter broadcast on BCCH. The parameter may also be sent to the MS on SACCH.

The meaning of different values of the parameter is specified as follows:

Value Meaning

00 Normal reporting of the six strongest cells, with known and allowed NCC part of BSIC, irrespective of the band used.

01 The MS shall report the strongest cell, with known and allowed NCC part of BSIC, in each of the frequency bands in the BA list, excluding the frequency band of the serving cell. The remaining positions in the measurement report shall be used for reporting of cells in the band of the serving cell. If there are still remaining positions, these shall be used to report the next strongest identified cells in the other bands irrespective of the band used.

10 The MS shall report the two strongest cells, with known and allowed NCC part of BSIC, in each of the frequency bands in the BA list, excluding the frequency band of the serving cell. The remaining positions in the measurement report shall be used for reporting of cells in the band of the serving cell. If there are still remaining positions, these shall be used to report the next strongest identified cells in the other bands irrespective of the band used.

11 The MS shall report the three strongest cells, with known and allowed NCC part of BSIC, in each of the frequency bands in the BA list, excluding the frequency band of the serving cell. The remaining positions in the measurement report shall be used for reporting of cells in the band of the serving cell. If there are still remaining positions, these shall be used to report the next strongest identified cells in the other bands irrespective of the band used.

8.4.4 Common aspects for the MS on a TCH or a SDCCH

Whether the MS is on a TCH or a SDCCH, if an SACCH message block is used for a different Layer 3 message, the measurement report that would otherwise be sent in that block is discarded and a new measurement report provided for the next SACCH message.

The MS shall also transmit a bit (DTX_USED) in the next SACCH message block, which indicates whether or not it has employed DTX during the reporting period. This bit shall be set even if just one burst in a TDMA frame in the reporting period was not transmitted due to DTX.

NOTE: A speech or user data frame subject to DTX may cross the "border" between two reporting periods, in which case both of the associated SACCH message blocks will have the DTX_USED flag set.

The measurements in the MS shall be based on the current BA list and the current NCC_PERMITTED (see table 1), available at the beginning of the reporting period. At the transition from idle mode to a TCH or a SDCCH the current BA list is the BA(BCCH), later the latest received complete BA(SACCH). A complete BA(SACCH) for a MS shall be that contained in SI 5 and additionally SI 5bis if the EXT-IND bit in the Neighbour Cell Description information element in both the SI 5 and SI 5bis messages indicates that each information element only carries part of the BA. If a SI 5ter message is subsequently received and not ignored (see 3GPP TS 04.18) the BA(SACCH) shall be modified accordingly.

At the transition from idle mode to a TCH or a SDCCH the current NCC is the NCC_PERMITTED received on the BCCH, later the latest NCC_PERMITTED received on the SACCH. The measurement process on carriers contained in both lists is, therefore, continuous.

If the current BA list does not refer to the serving cell, e.g. after a handover, this shall be indicated and no measurement values for cells in the BA list shall be reported.

If the MS returns to the previous cell after a failure of the handover procedure the description above applies. As a consequence, a BA list (and/or NCC_PERMITTED) received on the SACCH in the cell to which the handover failed shall be regarded as the current ones, which may lead to interruptions in the measurement reporting as the BA list does not refer to the serving cell. As an option, the MS may in this case remember the last received BA list and NCC_PERMITTED in the old cell and regard those as the current ones when returning.

What is said in this subclause about the BA list also applies to the GSM neighbour cell list when using enhanced measurement reporting and to the 3G neighbour cell list for a multi-RAT MS. The rules for building of and changing between neighbour cell lists are defined in 3GPP TS 04.18.

8.4.5 Measurement reporting for the BSS

Unless otherwise specified by the operator, the BSS shall make the same RXLEV (full and sub) and RXQUAL (full and sub) assessments as described for the MS for all TCH’s and SDCCH’s assigned to an MS, using the associated reporting periods. These values, together with the reported values from the MS, shall be transmitted to the BSC as described in the 3GPP TS 08.58.

8.4.6 Extended measurement reporting

When on a TCH or SDCCH, the mobile station may receive an Extended Measurement Order (EMO) message. The mobile station shall then, during one reporting period, perform received signal level measurements according to the frequency list contained in the EMO message. BSIC decoding is not required for these frequencies. The mobile station shall then transmit the measurement results in one single Extended Measurement Report message, containing the following:

– RXLEV (as defined in subclause 8.1.4) for the carriers specified by the last received EMO message. If the EMO contains more than 21 carriers, only the 21 first carriers in the sorted EXTENDED MEASUREMENT FREQUENCY LIST (in the EMO) are measured and reported.

– DTX USED, as defined in subclause 8.4.4.

NOTE: the position of the signal strength measurement samples performed by the mobile station, and the duration of these samples are not known in a TDMA frame. Consequently, in case the signal level on the carrier the MS has to monitor is not constant, the MS will report as the RXLEV value, the signal strength measurements performed during its sampling period. This value can be different from the mean value of the signal level on the whole frame.

If reporting is not possible due to requirements to send other Layer 3 messages, the measurements shall either be discarded and new measurements scheduled at the next possible opportunity or saved and transmitted at the next possible opportunity. If extended measurements can not be reported within 10 seconds after the triggering EMO was received, they shall be discarded (and not reported).

If the EMO message contains frequencies outside the MS’ frequency band, the MS shall set the corresponding RXLEV value(s) to zero.

After a successful channel change, no Extended Measurement Report shall be sent if the EMO was received before that channel change.

After having performed Extended Measurements during one reporting period, the mobile station shall resume the measurements according to the current BA list. This applies for each rescheduling of the Extended measurements.

8.4.7 Additional cell reporting requirements for multi-RAT MS

A multi-RAT MS shall report the number of best valid cells, in each supported other radio access technology/mode in the neighbour cell list, according to the value of the parameters XXX_MULTIRAT_REPORTING (XXX indicates radio access technology/mode). The remaining positions in the measurement report shall be used for reporting of GSM cells as defined in subclause 8.4.3. If there are still remaining positions, these shall be used to report the next best valid cells in other radio access technologies. The best cell is the cell with the highest reported value (see subclause 8.1.5).

If the neighbour cell list contains a UTRAN frequency for which RSSI shall be reported, that report shall be included whenever a cell on that frequency is reported (RSSI shall be reported once per frequency occurence in the neighbouring cell list). RSSI measurements for frequencies contained in the neighbour cell list shall be reported with high priority and shall be reported before measurements on valid 3G cell, in case of not available positions.

Note: The parameter XXX_MULTIRAT_REPORTING indicates a number of cells to be reported in a measurement report message and does not include the number of places taken by RSSI reporting in the measurement report message.

If no measurements have been performed on a cell since last report, the cell shall not be included in the report.

For UTRAN FDD, valid cells are identified cells where the primary CPICH has been received when using the scrambling code provided for that frequency in the neighbour cell list.

For UTRAN TDD, valid cells are identified cells with correct cell parameter and sync case provided for that frequency in the neighbour cell list.

For cdma2000, valid cells are identified cells with correct Pilot PN sequence offset index (PILOT_PN, as defined in TIA/EIA/IS-2000-A) provided for that frequency in the neighbour cell list.

The XXX_MULTIRAT_REPORTING parameters are broadcast on BCCH and PBCCH. An MS attached to GPRS shall use the parameters broadcast on PBCCH if it exists. In all other cases, the MS shall use the parameters broadcast on BCCH. The parameters may also be sent to the MS on SACCH.

8.4.8 Enhanced Measurement Reporting

The network may request the MS to report serving cell and neighbour cell measurements with Enhanced Measurement Report message by the parameter REPORT_TYPE, provided that BSIC for all GSM neighbour cells has been sent to the MS (See 3GPP TS 04.18). This reporting is referred as Enhanced Measurement Reporting.

If Enhanced Measurement Reporting is used, the BCCH carriers and corresponding valid BSICs of the GSM neighbour cells are sent to the MS within System Information messages and MEASUREMENT INFORMATION message (See 3GPP TS 04.18). The MEASUREMENT INFORMATION message also includes the parameters SERVING_BAND_REPORTING, MULTIBAND_REPORTING, XXX_MULTIRAT_REPORTING (XXX indicates other radio access technology/mode), XXX_REPORTING_THRESHOLD (XXX indicates GSM band or other radio access technology/mode), XXX_REPORTING_OFFSET (XXX indicates GSM band or other radio access technology/mode), REP_PRIORITY, REPORTING_RATE and INVALID_BSIC_REPORTING.

Only GSM cells with the valid BSIC shall be reported unless otherwise stated.

8.4.8.1 Reporting Priority

The MS shall include the neighbour cell measurement results using the following priority order:

  1. the number of strongest GSM cells with known and valid BSIC and with a reported value equal or greater than XXX_REPORTING_THRESHOLD, in the frequency band of the serving cell, according to the value of the parameter SERVING_BAND_REPORTING;
  2. the number of strongest GSM cells with known and valid BSIC and with a reported value equal or greater than XXX_REPORTING_THRESHOLD, in each of the frequency bands in the BA list, excluding the frequency band of the serving cell, according to the value of the parameter MULTIBAND_REPORTING;
  3. the number of best valid cells and with a reported value equal or greater than XXX_REPORTING_THRESHOLD, in each supported other radio access technology/mode in the 3G neighbour cell list, according to the value of the parameters XXX_MULTIRAT_REPORTING. A valid cell is defined in subclause 8.4.7.
  4. The remaining GSM cells with known and valid BSIC or, if indicated by the parameter INVALID_BSIC_REPORTING, with known and allowed NCC part of the BSIC in any frequency band and valid cells of other radio access technologies. Except for cells with high reporting priority as indicated with by the parameter REP_PRIORITY, these cells may be reported less frequently, if indicated by the parameter REPORTING_RATE, but at least once in four consecutive measurement reports. For those cells that are not reported in every measurement report, the MS shall average the measurements of the current and the previous reporting period (i.e. over two reporting periods).

For UTRAN FDD cells within this priority level, the reporting priority shall always be based on RSCP even if Ec/No is reported.

If the neighbour cell list contains a UTRAN frequency for which RSSI shall be reported, that report shall be included whenever a cell on that frequency is reported, as described in 8.4.7.

For each of the priority levels above, the following shall apply:

– if the number of valid cells is less than indicated the unused positions in the report shall be left for the lower prioritised cells;

– if there is not enough space in the report for all valid cells, the cells shall be reported that has the highest sum of the reported value (RXLEV or as defined in subclause 8.1.5) and the parameter XXX_REPORTING_OFFSET for respective radio access technology/mode. Note that this parameter shall not affect the actual reported value. If a cell can not be reported due to lack of space in the report, then no cell with a lower value shall be reported, even if one of these cells with a lower value would fit in the report.

8.4.8.2 Measurement Reporting

The reporting period shall be as specified in 8.4.1 for the MS on a TCH and as specified in 8.4.2 for the MS on a SDCCH.

When on a TCH, the MS shall assess during the reporting period and transmit to the BSS in the next SACCH message block the following:

– RXLEV for neighbour cells in the order defined in 8.4.8.1. For a cell of other radio access technology, see subclause 8.1.5.

– RXQUAL_FULL:
RXQUAL for the full set of TCH and SACCH TDMA frames. The full set of TDMA frames is either 100 (i.e. 104 ‑ 4 idle) frames for a full rate TCH or 52 frames for a half‑rate TCH.

– RXLEV_VAL:
RXLEV measured on SACCH frames and on the 4 last time slots of each fully received and correctly decoded block, whether the DTX was used in downlink or not. For speech traffic channels, blocks that have not been erased, shall be considered as correctly decoded. For non-transparent data, blocks are considered as correctly decoded according the CRC received. For transparent data, all blocks are considered as correctly decoded.

– MEAN_BEP and CV_BEP:
The average over the reporting period of the Mean and Coefficient of Variation of the Bit Error Probability measures excluding CV_BEPblock measurements from SACCH blocks (see subclause 8.2.3).

– NBR_RCVD_BLOCKS:
The number of correctly decoded blocks, as defined for RXLEV_VAL, (excluding all SID frames, RATSCCH, SACCH and FACCH blocks) that were completed during the measurement report period. As an exception, FACCH blocks shall be included in the case of signalling only mode.

Note: In some cases more than one data frame needs to be received in order to identify a block as correctly decoded, e.g. for 14.4 data where one RLP frame consists of two consecutive blocks. In some cases a single block carries multiple RLP frames in which case it is sufficient that one of those RLP frames is correctly received.

– BSIC_SEEN:
Indicates if a GSM cell with invalid BSIC and allowed NCC part of the BSIC is one of the six strongest cells.

In case of a multislot configuration the MS shall report the following according to the definition above:

– on the main SACCH: the RXLEV values from the adjacent cells, BSIC_SEEN, RXLEV_VAL and NBR_RCVD_BLOCKS from the main channel, the worst RXQUAL_FULL value and the worst MEAN_BEP value from the main channel and the unidirectional channels and the CV_BEP value from the same channel as the reported MEAN_BEP;

  • on each other bi‑directional SACCH: the RXLEV values from the adjacent cells, BSIC_SEEN, RXLEV_VAL, NBR_RCVD_BLOCKS, RXQUAL_FULL, MEAN_BEP and CV_BEP from the corresponding channel.

When on a SDCCH, the MS shall assess during the reporting period and transmit to the BSS in the next SACCH message block the following:

– RXLEV for neighbour cells as defined in 8.4.8.1. For a cell of other radio access technology, see subclause 8.1.5.

  • RXLEV_VAL, NBR_RCVD_BLOCKS, RXQUAL_FULL, MEAN_BEP and CV_BEP for the full set of 12 (8 SDCCH and 4 SACCH) TDMA frames within the reporting period. As DTX is not allowed on the SDCCH, measurements on all 12 TDMA frames shall be included for RXLEV_VAL.

– BSIC_SEEN:
Indicates if a GSM cell with invalid BSIC and allowed NCC part of the BSIC is one of the six strongest cells.

The common aspects for the MS on a TCH or a SDCCH as defined in 8.4.4 shall apply.

8.5 Absolute MS‑BTS distance

8.5.1 General

The Absolute MS‑BTS distance may be employed by the network as a criterion in the handover processes.

8.5.2 Physical parameter

The information being used by the BSS to perform "adaptive frame alignment" (3GPP TS 05.10) in the MS is a representation of the absolute distance of the MS to the serving BTS.

This absolute distance may be used by the BSS to prevent MS from grossly exceeding the planned cell boundaries.

The allowable distance is administered on a cell by cell basis by the network operator.