6.11 Delay

26.1313GPPRelease 17RequirementsTerminal acoustic characteristics for telephonyTS

6.11.0 UE delay definition

6.11.0.1 Acoustic interfaces

For UMTS circuit-switched operation and 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.

6.11.0.2 Electrical interfaces

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.

6.11.1 Handset UE

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 UMTS circuit-switched AMR-WB speech codec operation, the sum of the UE delays in sending and receiving directions (TS + TR) shall in any case be ≤ 220ms and should be ≤ 185ms.

NOTE: A delay ≤ 185 ms might not be achievable in some cases due to UE implementation trade-offs between delay and other parameters such as speech quality enhancement, performance of noise reduction or UE power consumption optimization, and UE implementation issues such as rebuffering between components.

For MTSI-based speech-only with LTE, NR or WLAN access in error and jitter free conditions and AMR-WB speech codec operation, the sum of the UE delays in sending and receiving directions (TS + TR) should be ≤ 150ms. If this performance objective cannot be met, the sum of the UE delays in sending and receiving directions (TS + TR) shall in any case be ≤ 190ms.

For MTSI-based speech-only with LTE, NR or WLAN access in conditions with simulated packet arrival time variations and packet loss and AMR-WB speech codec operation, the sum of the UE delays in sending and receiving directions (TS + TR) shall be less than or equal to the delay requirements in Table 16a1, while meeting the speech quality targets defined.

NOTE: The UE delay requirements for MTSI-based speech-only with LTE, NR or WLAN access are derived from:

– A speech frame buffering and codec look-ahead of 25ms.

– 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 16a1, and 80ms for test condition 2 of Table 16a1.

– 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 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

TS + TR ≤ 150ms

TS + TR ≤ 190ms

No requirement, reference score
MOS-LQOREF

1

dly_profile_20msDRX_10pct_BLER_e2e

TS + TR ≤ 150ms

TS + TR ≤ 190ms

MOS-LQOTEST
MOS-LQOREF – 0.3

2

dly_profile_40msDRX_10pct_BLER_e2e

TS + TR ≤ 190ms

TS + TR ≤ 230ms

MOS-LQOTEST
MOS-LQOREF – 0.3

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 target BLER in sending and receiving directions of 10%, with +/- 3ms of EPC jitter. Delay profiles are injected at the IP layer of the test system. Delay profiles are attached electronically to document 3GPP TS 26.132 [1]. The delay profiles in test condition 1 and 2 are static delay variation conditions and do not expose the UE to packet delay variations in the full range of the packet delay budget as defined for QCI1 in 3GPP TS 23.203 [18]. A third test condition that exposes the UE to non-stationary packet delay variations experienced in live operation and packet delay variations in the full range of the packet delay budget for QCI1, and accompanied delay and speech quality requirements, is for further study.

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 3GPP TS 26.132.

6.11.2 Headset UE

6.11.2.1 Wired headset

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 UMTS circuit-switched AMR-WB speech codec operation, the sum of the UE delays in sending and receiving directions (TS + TR) shall in any case be ≤ 220ms and should be ≤ 185ms.

NOTE: A delay ≤ 185 ms might not be achievable in some cases due to UE implementation trade-offs between delay and other parameters such as speech quality enhancement, performance of noise reduction or UE power consumption optimization, and UE implementation issues such as rebuffering between components.

For MTSI-based speech-only with LTE, NR or WLAN access in error and jitter free conditions and AMR-WB speech codec operation, the sum of the UE delays in sending and receiving directions (TS + TR) should be ≤ 150ms. If this performance objective cannot be met, the sum of the UE delays in sending and receiving directions (TS + TR) shall in any case be ≤ 190ms.

For MTSI-based speech-only with LTE, NR or WLAN access in conditions with simulated packet arrival time variations and packet loss and AMR-WB speech codec operation, the sum of the UE delays in sending and receiving directions (TS + TR) shall be less than or equal to the delay requirements in Table 16a2, while meeting the speech quality targets defined.

NOTE: The UE delay requirements for MTSI-based speech-only with LTE, NR or WLAN access are derived from:

– A speech frame buffering and codec look-ahead of 25ms.

– 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 16a2, and 80ms for test condition 2 of Table 16a2.

– 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 16a2: 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

TS + TR ≤ 150ms

TS + TR ≤ 190ms

No requirement, reference score
MOS-LQOREF

1

dly_profile_20msDRX_10pct_BLER_e2e

TS + TR ≤ 150ms

TS + TR ≤ 190ms

MOS-LQOTEST
MOS-LQOREF – 0.3

2

dly_profile_40msDRX_10pct_BLER_e2e

TS + TR ≤ 190ms

TS + TR ≤ 230ms

MOS-LQOTEST
MOS-LQOREF – 0.3

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 target BLER in sending and receiving directions of 10%, with +/- 3ms of EPC jitter. Delay profiles are injected at the IP layer of the test system. Delay profiles are attached electronically to document 3GPP TS 26.132 [1]. The delay profiles in test condition 1 and 2 are static delay variation conditions and do not expose the UE to packet delay variations in the full range of the packet delay budget as defined for QCI1 in 3GPP TS 23.203 [18]. A third test condition that exposes the UE to non-stationary packet delay variations experienced in live operation and packet delay variations in the full range of the packet delay budget for QCI1, and accompanied delay and speech quality requirements, is for further study.

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 3GPP TS 26.132.

6.11.2.2 Wireless headset

For further study.

6.11.3 Electrical interface UE

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 BD to be considered in the performance requirements and objectives depends on the type of electrical interface UE and is given by Table 16a3.

Table 16a3: Delay budget for different types of electrical interface UE

Electrical interface type

BD [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 UMTS circuit-switched AMR-WB speech codec operation, the sum of the UE delays in sending and receiving directions (TS + TR) shall in any case be ≤ 220+BD ms and should be ≤ 185+BD ms.

NOTE1: A delay ≤ 185+BD ms might not be achievable in some cases due to UE implementation trade-offs between delay and other parameters such as speech quality enhancement, performance of noise reduction or UE power consumption optimization, and UE implementation issues such as rebuffering between components.

For MTSI-based speech-only with LTE, NR or WLAN access in error and jitter free conditions and AMR-WB speech codec operation, the sum of the UE delays in sending and receiving directions (TS + TR) should be ≤ 150+BD ms. If this performance objective cannot be met, the sum of the UE delays in sending and receiving directions (TS + TR) shall in any case be ≤ 190+BD ms.

For MTSI-based speech-only with LTE, NR or WLAN access in conditions with simulated packet arrival time variations and packet loss and AMR-WB speech codec operation, the sum of the UE delays in sending and receiving directions (TS + TR) shall be less than or equal to the delay requirements in Table 16a4, while meeting the speech quality targets defined.

NOTE2: The UE delay requirements for MTSI-based speech-only with LTE, NR or WLAN access are derived from:

– A speech frame buffering and codec look-ahead of 25ms.

– 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 16a4, and 80ms for test condition 2 of Table 16a4.

– 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 16a4: 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

TS + TR ≤ 150+BD ms

TS + TR ≤ 190+BD ms

No requirement, reference score
MOS-LQOREF

1

dly_profile_20msDRX_10pct_BLER_e2e

TS + TR ≤ 150+BD ms

TS + TR ≤ 190+BD ms

MOS-LQOTEST
MOS-LQOREF – 0.3

2

dly_profile_40msDRX_10pct_BLER_e2e

TS + TR ≤ 190+BD ms

TS + TR ≤ 230+BD ms

MOS-LQOTEST
MOS-LQOREF – 0.3

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 target BLER in sending and receiving directions of 10%, with +/- 3ms of EPC jitter. Delay profiles are injected at the IP layer of the test system. Delay profiles are attached electronically to document 3GPP TS 26.132 [1]. The delay profiles in test condition 1 and 2 are static delay variation conditions and do not expose the UE to packet delay variations in the full range of the packet delay budget as defined for QCI1 in 3GPP TS 23.203 [18]. A third test condition that exposes the UE to non-stationary packet delay variations experienced in live operation and packet delay variations in the full range of the packet delay budget for QCI1, and accompanied delay and speech quality requirements, is for further study.

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 3GPP TS 26.132.