Content for TS 26.131 Word version: 18.1.0

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7.11 Delay 7.11.0 UE delay definition 7.11.1 Handset UE 7.11.2 Headset UE 7.11.3 Electrical interface UE
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7.11 Delay p. 83

7.11.0 UE delay definition p. 83

7.11.0.1 Acoustic interfaces |R17| p. 83

For MTSI-based speech with LTE, NR or WLAN access, the UE delays in the send and receive directions are defined for acoustic interfaces as:

The UE delay in the send (uplink) direction is the delay between the first acoustic event at the MRP to the last bit of the corresponding speech frame at the UE antenna
The UE delay in the receive (downlink) direction is the delay between the first bit of a speech frame at the UE antenna and the first acoustic event at the DRP corresponding to that speech frame.

NOTE:

In order to harmonize UMTS and LTE delay definitions, the reference points for UMTS UE delay have been changed in Rel-12. Prior to Rel-12, the UE reference points for UMTS were implicitly defined by the compensation factors declared by system simulator vendors, i.e. half of the air interface delay was attributed to the UE, and the last acoustic event at DRP was used for the receive measurement instead of the first.

Considering 10ms for half of the transmission time in each direction of a UMTS call, a speech frame size of 20ms, a codec look-ahead of 5ms, and a difference between the first and the last acoustic event of 20 ms, the previous reference points took into account a UE implementation independent delay of 2x10ms + 25 ms + 20 ms = 65 ms. The same UE delay remains in the new definition above, which attributes the full air interface delay to the UE but uses the first acoustic event at the DRP, instead of the last (2x20ms + 25 ms + 0 ms = 65 ms). Hence, the UMTS requirements with these new reference points remain the same.

7.11.0.2 Electrical interfaces |R17| p. 84

The UE delays in the send and receive directions are defined for electrical interfaces as:

The UE delay in the send (uplink) direction is the delay between the first electrical event at the input of the electrical interface (analogue or wired digital connection) or first bit of a speech frame at the UE antenna of the wireless digital interface (wireless digital connection) to the last bit of the corresponding speech frame at the UE antenna
The UE delay in the receive (downlink) direction is the delay between the first bit of a speech frame at the UE antenna and the first electrical event at the output of the electrical interface (analogue or wired digital connection) or first bit of a speech frame at the UE antenna of the wireless digital interface (wireless digital connection) corresponding to that speech frame.

7.11.1 Handset UE p. 84

It is in general desirable to minimize UE delays to ensure low enough end-to-end delays and hence a good conversational experience, guidance is found in ITU-T Recommendation G.114.

For MTSI-based speech-only with LTE, NR or WLAN access in error and jitter free conditions and EVS speech codec operation, the sum of the UE delays in sending and receiving directions (T_S + T_R) should be ≤ 157ms. If this performance objective cannot be met, the sum of the UE delays in sending and receiving directions (T_S + T_R) shall in any case be ≤ 197ms.

For MTSI-based speech-only with LTE, NR or WLAN access in conditions with simulated packet arrival time variations and packet loss and EVS speech codec operation, the sum of the UE delays in sending and receiving directions (T_S + T_R) shall be less than or equal to the delay requirements in Table 32a1, while meeting the speech quality targets defined.

Table 32a1: UE delay and speech quality requirements for LTE, NR and WLAN access

Test Condition	Delay and Loss Profile (Note 1)	Performance Objectives for Maximum Delay	Requirements for Maximum Delay	Speech Quality Requirements (Note 2)
0	Error and jitter free condition	T_S + T_R ≤ 157ms	T_S + T_R ≤ 197ms	No requirement, reference score MOS-LQO_REF
1	dly_profile_20msDRX_10pct_BLER_e2e	T_S + T_R ≤ 157ms	T_S + T_R ≤ 197ms	MOS-LQO_TEST ≥ MOS-LQO_REF - 0.4
2	dly_profile_40msDRX_10pct_BLER_e2e	T_S + T_R ≤ 197ms	T_S + T_R ≤ 237ms	MOS-LQO_TEST ≥ MOS-LQO_REF - 0.4
3	dly_profile_40msDRX_22pct_BLER_e2e	T_S + T_R ≤ 197ms	T_S + T_R ≤ 237ms	MOS-LQO_TEST ≥ MOS-LQO_REF - 1.0
NOTE 1: The delay profiles for test condition 1 and 2 are theoretically constructed to simulate a semi-persistent scheduling transmission scheme with DRX enabled and initial BLER in sending and receiving directions of 10%, with +/- 3ms of EPC jitter. The delay profile for test condition 3 is theoretically constructed to simulate a semi-persistent scheduling transmission scheme with DRX enabled and initial BLER in sending and receiving directions of 22%, with +/- 6ms of EPC jitter. Delay profiles are injected at the IP layer of the test system. Delay profiles are attached electronically to document TS 26.132. NOTE 2: The purpose of this test is to provide a relative comparison of the objective speech quality between the reference and test conditions. This test is not to be construed as a method to evaluate the absolute objective speech quality of the device.

Compliance shall be checked by the relevant tests described in TS 26.132. When tested in EVS 13.2kbit/s channel aware mode, the UE shall meet the additional requirements in Table 32b1:

Table 32b1: UE delay and speech quality requirements for LTE, NR and WLAN access when tested in EVS 13.2kbit/s channel aware mode

Test Condition	Delay and Loss Profile (Note 1)	Performance Objectives for Maximum Delay	Requirements for Maximum Delay	Speech Quality Requirements (Note 2)
0	Error and jitter free condition	T_S + T_R ≤ 157ms	T_S + T_R ≤ 197ms	No requirement, reference score MOS-LQO_REF
1	dly_profile_20msDRX_10pct_BLER_e2e	T_S + T_R ≤ [157]ms	T_S + T_R ≤ 197ms	MOS-LQO_TEST ≥ MOS-LQO_REF - 0.3
2	dly_profile_40msDRX_10pct_BLER_e2e	T_S + T_R ≤ [197]ms	T_S + T_R ≤ 237ms	MOS-LQO_TEST ≥ MOS-LQO_REF - 0.3
3	dly_profile_40msDRX_22pct_BLER_e2e	T_S + T_R ≤ [197]ms	T_S + T_R ≤ 237ms	MOS-LQO_TEST ≥ MOS-LQO_REF - 0.5
NOTE 1: The delay profiles for test condition 1 and 2 are theoretically constructed to simulate a semi-persistent scheduling transmission scheme with DRX enabled and initial BLER in sending and receiving directions of 10%, with +/- 3ms of EPC jitter. The delay profiles for test condition 3 is theoretically constructed to simulate a semi-persistent scheduling transmission scheme with DRX enabled and initial BLER in sending and receiving directions of 22%, with +/- 6ms of EPC jitter. Delay profiles are injected at the IP layer of the test system. Delay profiles are attached electronically to document TS 26.132. NOTE 2: The purpose of this test is to provide a relative comparison of the objective speech quality between the reference and test conditions. This test is not to be construed as a method to evaluate the absolute objective speech quality of the device.

Compliance shall be checked by the relevant tests described in TS 26.132.

7.11.2 Headset UE p. 85

7.11.2.1 Wired headset p. 85

It is in general desirable to minimize UE delays to ensure low enough end-to-end delays and hence a good conversational experience, guidance is found in ITU-T Recommendation G.114.

For MTSI-based speech-only with LTE, NR or WLAN access in conditions with simulated packet arrival time variations and packet loss and EVS speech codec operation, the sum of the UE delays in sending and receiving directions (T_S + T_R) shall be less than or equal to the delay requirements in Table 32a2, while meeting the speech quality targets defined.

Table 32a2: UE delay and speech quality requirements for LTE, NR and WLAN access

Test Condition	Delay and Loss Profile (Note 1)	Performance Objectives for Maximum Delay	Requirements for Maximum Delay	Speech Quality Requirements (Note 2)
0	Error and jitter free condition	T_S + T_R ≤ 157ms	T_S + T_R ≤ 197ms	No requirement, reference score MOS-LQO_REF
1	dly_profile_20msDRX_10pct_BLER_e2e	T_S + T_R ≤ 157ms	T_S + T_R ≤ 197ms	MOS-LQO_TEST ≥ MOS-LQO_REF - 0.4
2	dly_profile_40msDRX_10pct_BLER_e2e	T_S + T_R ≤ 197ms	T_S + T_R ≤ 237ms	MOS-LQO_TEST ≥ MOS-LQO_REF - 0.4
3	dly_profile_40msDRX_22pct_BLER_e2e	T_S + T_R ≤ 197ms	T_S + T_R ≤ 237ms	MOS-LQO_TEST ≥ MOS-LQO_REF - 1.0
NOTE 1: The delay profiles for test condition 1 and 2 are theoretically constructed to simulate a semi-persistent scheduling transmission scheme with DRX enabled and initial BLER in sending and receiving directions of 10%, with +/- 3ms of EPC jitter. The delay profile for test condition 3 is theoretically constructed to simulate a semi-persistent scheduling transmission scheme with DRX enabled and initial BLER in sending and receiving directions of 22%, with +/- 6ms of EPC jitter. Delay profiles are injected at the IP layer of the test system. Delay profiles are attached electronically to document TS 26.132. NOTE 2: The purpose of this test is to provide a relative comparison of the objective speech quality between the reference and test conditions. This test is not to be construed as a method to evaluate the absolute objective speech quality of the device.

Compliance shall be checked by the relevant tests described in TS 26.132. When tested in EVS 13.2kbit/s channel aware mode, the UE shall meet the additional requirements in Table 32b2.

Table 32b2: UE delay and speech quality requirements for LTE, NR and WLAN access when tested in EVS 13.2kbit/s channel aware mode

Test Condition	Delay and Loss Profile (Note 1)	Performance Objectives for Maximum Delay	Requirements for Maximum Delay	Speech Quality Requirements (Note 2)
0	Error and jitter free condition	T_S + T_R ≤ 157ms	T_S + T_R ≤ 197ms	No requirement, reference score MOS-LQO_REF
1	dly_profile_20msDRX_10pct_BLER_e2e	T_S + T_R ≤ 157ms	T_S + T_R ≤ 197ms	MOS-LQO_TEST ≥ MOS-LQO_REF - 0.3
2	dly_profile_40msDRX_10pct_BLER_e2e	T_S + T_R ≤ 197ms	T_S + T_R ≤ 237ms	MOS-LQO_TEST ≥ MOS-LQO_REF - 0.3
3	dly_profile_40msDRX_22pct_BLER_e2e	T_S + T_R ≤ 197ms	T_S + T_R ≤ 237ms	MOS-LQO_TEST ≥ MOS-LQO_REF - 0.5
NOTE 1: The delay profiles for test condition 1 and 2 are theoretically constructed to simulate a semi-persistent scheduling transmission scheme with DRX enabled and initial BLER in sending and receiving directions of 10%, with +/- 3ms of EPC jitter. The delay profiles for test condition 3 is theoretically constructed to simulate a semi-persistent scheduling transmission scheme with DRX enabled and initial BLER in sending and receiving directions of 22%, with +/- 6ms of EPC jitter. Delay profiles are injected at the IP layer of the test system. Delay profiles are attached electronically to document TS 26.132. NOTE 2: The purpose of this test is to provide a relative comparison of the objective speech quality between the reference and test conditions. This test is not to be construed as a method to evaluate the absolute objective speech quality of the device.

Compliance shall be checked by the relevant tests described in TS 26.132.

7.11.2.2 Wireless headset p. 87

For further study.

7.11.3 Electrical interface UE |R17| p. 87

It is in general desirable to minimize UE delays to ensure low enough end-to-end delays and hence a good conversational experience, guidance is found in ITU-T Recommendation G.114.

The delay budget B_D to be considered in the performance requirements and objectives depends on the type of electrical interface UE and is given by Table 32c1.

Table 32c1: Delay budget for different types of electrical interface UE

Electrical interface type	B_D [ms]
Analogue	0
Wireless digital	20
Wired digital	20
NOTE: The delay for analogue to digital conversion (and vice versa) in the wired digital connection is considered to be part of the budget allowance for vendor specific implementation in the UE delay requirements.

For MTSI-based speech-only with LTE, NR or WLAN access in error and jitter free conditions and EVS speech codec operation, the sum of the UE delays in sending and receiving directions (T_S + T_R) should be ≤ 157+B_D ms. If this performance objective cannot be met, the sum of the UE delays in sending and receiving directions (T_S + T_R) shall in any case be ≤ 197+B_D ms.

For MTSI-based speech-only with LTE, NR or WLAN access in conditions with simulated packet arrival time variations and packet loss and EVS speech codec operation, the sum of the UE delays in sending and receiving directions (T_S + T_R) shall be less than or equal to the delay requirements in Table 32c2, while meeting the speech quality targets defined.

A codec algorithmic delay of 32ms including speech frame buffering and encoder lookahead.
An air interface transmission time of 1ms on receive and 1ms on the send direction.
A budget allowance for a jitter buffer depth of 40ms for error and jitter free conditions and test conditions 0 and 1 of Table 32c2, and 80ms for test condition 2 and 3 of Table 32c2. This budget is also applied in Table 32c3 (when testing in EVS 13.2 kbit/s channel-aware mode).
A budget allowance for vendor specific implementation of 83ms corresponding to the performance objective and 123ms corresponding to the required maximum UE send and receive delay.

Table 32c2: UE delay and speech quality requirements for LTE, NR and WLAN access

Table 16a1: UE delay and speech quality requirements for LTE, NR and WLAN access

Test Condition	Delay and Loss Profile (Note 1)	Performance Objectives for Maximum Delay	Requirements for Maximum Delay	Speech Quality Requirements (Note 2)
0	Error and jitter free condition	T_S + T_R ≤ 157+B_D ms	T_S + T_R ≤ 197+B_D ms	No requirement, reference score MOS-LQO_REF
1	dly_profile_20msDRX_10pct_BLER_e2e	T_S + T_R ≤ 157+B_D ms	T_S + T_R ≤ 197+B_D ms	MOS-LQO_TEST ≥ MOS-LQO_REF - 0.4
2	dly_profile_40msDRX_10pct_BLER_e2e	T_S + T_R ≤ 197+B_D ms	T_S + T_R ≤ 237+B_D ms	MOS-LQO_TEST ≥ MOS-LQO_REF - 0.4
3	dly_profile_40msDRX_22pct_BLER_e2e	T_S + T_R ≤ 197+B_D ms	T_S + T_R ≤ 237+B_D ms	MOS-LQO_TEST ≥ MOS-LQO_REF - 1.0
NOTE 1: The delay profiles for test condition 1 and 2 are theoretically constructed to simulate a semi-persistent scheduling transmission scheme with DRX enabled and initial BLER in sending and receiving directions of 10%, with +/- 3ms of EPC jitter. The delay profile for test condition 3 is theoretically constructed to simulate a semi-persistent scheduling transmission scheme with DRX enabled and initial BLER in sending and receiving directions of 22%, with +/- 6ms of EPC jitter. Delay profiles are injected at the IP layer of the test system. Delay profiles are attached electronically to document TS 26.132. NOTE 2: The purpose of this test is to provide a relative comparison of the objective speech quality between the reference and test conditions. This test is not to be construed as a method to evaluate the absolute objective speech quality of the device.

Compliance shall be checked by the relevant tests described in TS 26.132. When tested in EVS 13.2kbit/s channel aware mode, the UE shall meet the additional requirements in Table 32c3.

Table 32c3: UE delay and speech quality requirements for LTE, NR and WLAN access when tested in EVS 13.2kbit/s channel aware mode

Test Condition	Delay and Loss Profile (Note 1)	Performance Objectives for Maximum Delay	Requirements for Maximum Delay	Speech Quality Requirements (Note 2)
0	Error and jitter free condition	T_S + T_R ≤ 157+B_D ms	T_S + T_R ≤ 197+B_D ms	No requirement, reference score MOS-LQO_REF
1	dly_profile_20msDRX_10pct_BLER_e2e	T_S + T_R ≤ 157+B_D ms	T_S + T_R ≤ 197+B_D ms	MOS-LQO_TEST ≥ MOS-LQO_REF - 0.3
2	dly_profile_40msDRX_10pct_BLER_e2e	T_S + T_R ≤ 197+B_D ms	T_S + T_R ≤ 237+B_D ms	MOS-LQO_TEST ≥ MOS-LQO_REF - 0.3
3	dly_profile_40msDRX_22pct_BLER_e2e	T_S + T_R ≤ 197+B_D ms	T_S + T_R ≤ 237+B_D ms	MOS-LQO_TEST ≥ MOS-LQO_REF - 0.5
NOTE 1: The delay profiles for test condition 1 and 2 are theoretically constructed to simulate a semi-persistent scheduling transmission scheme with DRX enabled and initial BLER in sending and receiving directions of 10%, with +/- 3ms of EPC jitter. The delay profiles for test condition 3 is theoretically constructed to simulate a semi-persistent scheduling transmission scheme with DRX enabled and initial BLER in sending and receiving directions of 22%, with +/- 6ms of EPC jitter. Delay profiles are injected at the IP layer of the test system. Delay profiles are attached electronically to document TS 26.132. NOTE 2: The purpose of this test is to provide a relative comparison of the objective speech quality between the reference and test conditions. This test is not to be construed as a method to evaluate the absolute objective speech quality of the device.

Compliance shall be checked by the relevant tests described in TS 26.132.