Over-the-air test method for two timing advances in multi-TRP scenario

Abstract

Example embodiments provide test methods for over-the-air two timing advances in a multi-TRP scenario A method comprises receiving, from a testing device, a configuration indicating that a multiple transmission and reception point operation is enabled with a two timing advance feature; detecting a first reference signal from a first transmission path and detect a second reference signal from a second transmission path, wherein the first reference signal and the second reference signal are detected with a timing difference; determining that the timing difference between the first reference signal and the second reference signal is not greater than a threshold; and when the timing difference is not greater than the threshold, adjusting at least one of a first uplink transmission timing based on the detection of the first reference signal or a second uplink transmission timing based on the detection the second reference signal. Devices, methods, and computer programs are disclosed.

Description

OVER-THE-AIR TEST METHOD FOR TWO TIMING ADVANCES IN MULTI-TRP SCENARIO TECHNICAL FIELD

[0001] The present application generally relates to information technology. Some example embodiments of the present application relate to a test method for verifying capability of a device under test to support two timing advances. BACKGROUND

[0002] Uplink transmissions from a client device (e.g., user equipment, UE) to a network device (e.g., a next generation NodeB, gNB) may need to be adjusted for time-alignment. One example mechanism to control uplink transmission timing is timing advance, wherein uplink transmission is synchronized with the network device based on timing advance value received by the client device from the network node. However, with development of communication systems, there is a need for further development of timing solutions. SUMMARY

[0003] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0004] Example embodiments may enable verifying if a device under test is compliant with two timing advancefeature when configured with multiple transmission and reception points. This may be achieved by the features of the independent claims. Further implementation forms are provided in the dependent claims, the description, and the drawings.

[0005] According to a first aspect, a method is provided, the method comprising receiving, from a testing device, a configuration indicating that a multiple transmission and reception point operation is enabled with a two timing advance feature; detecting a first reference signal from a first transmission path and detecting a second reference signal from a second transmission path, wherein the first reference signal and the second reference signal are detected with a timing difference; determining that the timing difference between the first reference signal and the second reference signal is not greater than a first threshold; and when the timing difference is not greater than the first threshold, adjusting at least one of a first uplink transmission timing based on the detection of the first reference signal or a second uplink transmission timing based on the detection the second reference signal. The method may be carried out, for example, by a device under test.

[0006] According to an example embodiment of the first aspect, the adjustment comprises at least one of performing a gradual adaptation by applying a plurality of autonomous adjustments or applying a received timing advance command.

[0007] According to an example embodiment of the first aspect, the method comprises detecting that the timing difference is caused by a delay of one of thefirst reference signal or the second reference signal; and performing a gradual adaptation of one of the first uplink transmission timing based on the delay detected for the first reference signal or the second uplink transmission timing based on the delay detected for the second reference signal by applying a plurality of autonomous adjustments.

[0008] According to an example embodiment of the first aspect, the method comprises detecting that the timing difference is caused by a first delay of the first reference signal and a second delay of the second reference signal; and performing gradual adaptations of both the first uplink transmission timing and the second uplink transmission timing by applying a plurality of autonomous adjustments in response to the detected delays.

[0009] According to an example embodiment of the first aspect, the method comprises receiving, from the testing device, a timing advance command notifying a timing advance value for the first transmission path; determining that a timing difference between the first uplink transmission and the second uplink transmission is not greater than a second threshold after applying the timing advance command; and if the second threshold is not exceeded, adjusting the first uplink transmission timing according to the timing advance command while the second uplink transmission timing is kept unchanged.

[0010] According to an example embodiment of the first aspect, the method comprises receiving, from the testing device, one or more timing advance commands notifying a timing advance value for the first transmission path and a timing advance value for thesecond transmission path; determining that a timing difference between the first uplink transmission and the second uplink transmission is not greater than a second threshold after applying the one or more timing advance commands; and if the second threshold is not exceeded, adjusting both the first uplink transmission timing and the second uplink transmission timing according to the one or more timing advance commands.

[0011] According to an example embodiment of the first aspect, the reference signal comprises a synchronization signal block or a channel state information reference signal.

[0012] According to an example embodiment of the first aspect, the configuration indicates two transmission configuration indicator states, the first transmission configuration indicator state comprising a first quasi co-location with the first reference signal to be used for the first uplink transmission and the second transmission configuration indicator state comprising a second quasi co-location with the second reference signal to be used for the second uplink transmission.

[0013] According to a second aspect, a method is provided, the method comprising transmitting, to a device under test, a configuration indicating that a multiple transmission and reception point operation is enabled with a two timing advance feature; transmitting, to the device under test, a first reference signal via a first transmission path and a second reference signal via a second transmission path, wherein the first reference signal and the second reference signal are transmitted with a relative delay such that a timingdifference between the first reference signal and the second reference signal to be detected by the device under test is not greater than a first threshold; and monitoring uplink transmissions of the device under test at the first transmission path and at the second transmission path to verify that the device under test is capable of performing one or more timing adjustments. The method may be carried out, for example, by a testing device.

[0014] According to an example embodiment of the second aspect, the monitoring comprises verifying that the device under test is capable of applying at least one of a gradual adaptation of uplink transmission timing or a timing advance command for expected uplink transmission without impacting accuracy of other uplink transmissions.

[0015] According to an example embodiment of the second aspect, the relative delay is caused by transmitting the first reference signal with a delay and transmitting the second reference signal without a delay, and the method further comprises adjusting the delay such that the timing difference of consecutive transmissions of the first reference signal and the second reference signal to be detected by the device under test is increased until the first threshold is met; and verifying that the device under test performed a gradual adaptation of the first uplink transmission timing in response to the delay while maintaining the second uplink transmission timing.

[0016] According to an example embodiment of the second aspect, the relative delay is caused by transmitting the first reference signal with a firstdelay and the second reference with a second delay, and the method further comprises adjusting both the first delay and the second delay such that the timing difference of consecutive transmissions of the first reference signal and the second reference signal to be detected by the device under test is increased until the first threshold is met; and verifying that the device under test performed gradual adaptations of both the first uplink transmission timing and the second uplink transmission timing in response to the first delay and the second delay.

[0017] According to an example embodiment of the second aspect, at least one of the first delay or the second delay is determined based on at least one of the first threshold, a timing error limit of the device under test or an accuracy in setting at least one of the first delay or the second delay.

[0018] According to an example embodiment of the second aspect, the method comprises determining a timing advance value for the first transmission path, wherein the timing advance value is determined such that a timing difference between the first uplink transmission timing and the second uplink transmission timing is not greater than a second threshold; transmitting, to the device under test, a timing advance command notifying the determined timing advance value for the first transmission path; and monitoring that the device under test is capable of adjusting the first uplink transmission timing according to the timing advance command while the second uplink transmission timing is unchanged.

[0019] According to an example embodiment of thesecond aspect, the method comprises determining a timing advance value for the first transmission path and for the second transmission path, wherein the timing advance values are determined such that a timing difference between the first uplink transmission timing and the second uplink transmission timing is not greater than a second threshold; transmitting, to the device under test, one or more timing advance commands notifying the timing advance value for the first transmission path and the timing advance value for the second transmission path; and monitoring that the device under test is capable of adjusting the first uplink transmission timing and the second uplink transmission timing according to the one or more timing advance commands.

[0020] According to an example embodiment of the second aspect, the timing advance value is further determined based on at least one of the first threshold, the relative delay, or the timing error limit.

[0021] According to an example embodiment of the second aspect, the reference signal comprises a synchronization signal block or a channel state information reference signal.

[0022] According to an example embodiment of the second aspect, the configuration indicates two transmission configuration indicator states, the first transmission configuration indicator state comprising a first quasi co-location with the first reference signal to be used for the first uplink transmission and the second transmission configuration indicator state comprising a second quasi co-location with the second reference signal to be used for the second uplink transmission.

[0023] According to a third aspect, a device may comprise at least one processor; and at least one memory including instructions which, when executed by the at least one processor, cause the device at least to receive, from a testing device, a configuration indicating that a multiple transmission and reception point operation is enabled with a two timing advance feature; detect a first reference signal from a first transmission path and detect a second reference signal from a second transmission path, wherein the first reference signal and the second reference signal are detected with a timing difference; determine that the timing difference between the first reference signal and the second reference signal is not greater than a first threshold; and when the timing difference is not greater than the first threshold, adjust at least one of a first uplink transmission timing based on the detection of the first reference signal or a second uplink transmission timing based on the detection the second reference signal.

[0024] According to an example embodiment of the third aspect, the adjustment comprises at least one of performing a gradual adaptation by applying a plurality of autonomous adjustments or applying a received timing advance command.

[0025] According to an example embodiment of the third aspect, the at least one memory comprises instructions which, when executed by the at least one processor, cause the device to detect that the timing difference is caused by a delay of one of the first reference signal or the second reference signal; and perform a gradual adaptation of one of the first uplinktransmission timing based on the delay detected for the first reference signal or the second uplink transmission timing based on the delay detected for the second reference signal by applying a plurality of autonomous adjustments.

[0026] According to an example embodiment of the third aspect, the at least one memory comprises instructions which, when executed by the at least one processor, cause the device to detect that the timing difference is caused by a first delay of the first reference signal and a second delay of the second reference signal; and perform gradual adaptations of both the first uplink transmission timing and the second uplink transmission timing in response to the detected delays by applying a plurality of adjustments.

[0027] According to an example embodiment of the third aspect, the at least one memory comprises instructions which, when executed by the at least one processor, cause the device to receive, from the testing device, a timing advance command notifying a timing advance value for the first transmission path; determine that a timing difference between the first uplink transmission and the second uplink transmission is not greater than a second threshold after applying the timing advance command; and if the second threshold is not exceeded, adjust the first uplink transmission timing according to the timing advance command while the second uplink transmission timing is kept unchanged.

[0028] According to an example embodiment of the third aspect, the at least one memory comprises instructions which, when executed by the at least one processor, cause the device to receive, from the testingdevice, one or more timing advance commands notifying a timing advance value for the first transmission path and a timing advance value for the second transmission path; determine that a timing difference between the first uplink transmission and the second uplink transmission is not greater than a second threshold after applying the one or more timing advance commands; and if the second threshold is not exceeded, adjust both the first uplink transmission timing and the second uplink transmission timing according to the one or more timing advance commands.

[0029] According to an example embodiment of the third aspect, the reference signal comprises a synchronization signal block or a channel state information reference signal.

[0030] According to an example embodiment of the third aspect, the configuration indicates two transmission configuration indicator states, the first transmission configuration indicator state comprising a first quasi co-location with the first reference signal to be used for the first uplink transmission and the second transmission configuration indicator state comprising a second quasi co-location with the second reference signal to be used for the second uplink transmission.

[0031] According to a fourth aspect, a device may comprise at least one processor; and at least one memory including instructions which, when executed by the at least one processor, cause the device at least to transmit, to a device under test, a configuration indicating that a multiple transmission and reception point operation is enabled with a two timing advancefeature; transmit, to the device under test, a first reference signal via a first transmission path and a second reference signal via a second transmission path, wherein the first reference signal and the second reference signal are transmitted with a relative delay such that a timing difference between the first reference signal and the second reference signal to be detected by the device under test is not greater than a first threshold; and monitor uplink transmissions of the device under test at the first transmission path and at the second transmission path to verify that the device under test is capable of performing one or more timing adjustments.

[0032] According to an example embodiment of the fourth aspect, the monitoring comprises verifying that the device under test is capable of applying at least one of a gradual adaptation of uplink transmission timing or a timing advance command for expected uplink transmission without impacting accuracy of other uplink transmissions.

[0033] According to an example embodiment of the fourth aspect, the relative delay is caused by transmitting the first reference signal with a delay and transmitting the second reference signal without a delay, and the at least one memory comprises instructions which, when executed by the at least one processor, cause the device to adjust the delay such that the timing difference of consecutive transmissions of the first reference signal and the second reference signal to be detected by the device under test is increased until the first threshold is met; and verify that the device under test performed a gradualadaptation of the first uplink transmission timing in response to the delay while maintaining the second uplink transmission timing.

[0034] According to an example embodiment of the fourth aspect, the relative delay is caused by transmitting the first reference signal with a first delay and the second reference signal with a second delay, and the at least one memory comprises instructions which, when executed by the at least one processor, cause the device to adjust both the first delay and the second delay such that the timing difference of consecutive transmissions of the first reference signal and the second reference signal to be detected by the device under test is increased until the first threshold is met; and verify that the device under test performed gradual adaptations of both the first uplink transmission timing and the second uplink transmission timing in response to the first delay and the second delay.

[0035] According to an example embodiment of the fourth aspect, at least one of the first delay or the second delay is determined based on at least one of the first threshold, a timing error limit of the device under test or an accuracy in setting at least one of the first delay or the second delay.

[0036] According to an example embodiment of the fourth aspect, the at least one memory comprises instructions which, when executed by the at least one processor, cause the device to determine a timing advance value for the first transmission path, wherein the timing advance value is determined such that a timing difference between the first uplink transmissiontiming and the second uplink transmission timing is not greater than a second threshold; transmit, to the device under test, a timing advance command notifying the determined timing advance value for the first transmission path; and monitor that the device under test is capable of adjusting the first uplink transmission timing according to the timing advance command while the second uplink transmission timing is unchanged.

[0037] According to an example embodiment of the fourth aspect, the at least one memory comprises instructions which, when executed by the at least one processor, cause the device to determine a timing advance value for the first transmission path and for the second transmission path, wherein the timing advance values are determined such that a timing difference between the first uplink transmission timing and the second uplink transmission timing is not greater than a second threshold; transmit, to the device under test, one or more timing advance commands notifying the timing advance value for the first transmission path and the timing advance value for the second transmission path; and monitor that the device under test is capable of adjusting the first uplink transmission timing and the second uplink transmission timing according to the one or more timing advance commands.

[0038] According to an example embodiment of the fourth aspect, the timing advance value is further determined based on at least one of the first threshold, the relative delay, or the timing error limit.

[0039] According to an example embodiment of the fourth aspect, the reference signal comprises asynchronization signal block or a channel state information reference signal.

[0040] According to an example embodiment of the fourth aspect, the configuration indicates two transmission configuration indicator states, the first transmission configuration indicator state comprising a first quasi co-location with the first reference signal to be used for the first uplink transmission and the second transmission configuration indicator state comprising a second quasi co-location with the second reference signal to be used for the second uplink transmission.

[0041] According to a fifth aspect, a computer program may be configured, when executed by a processor, to cause a device at least to perform the following: receive, from a testing device, a configuration indicating that a multiple transmission and reception point operation is enabled with a two timing advance feature; detect a first reference signal from a first transmission path and detect a second reference signal from a second transmission path, wherein the first reference signal and the second reference signal are detected with a timing difference; determining that the timing difference between the first reference signal and the second reference signal is not greater than a first threshold; and when the timing difference is not greater than the first threshold, adjust at least one of a first uplink transmission timing based on the detection of the first reference signal or a second uplink transmission timing based on the detection the second reference signal. The computer program may further comprise instructions for causing the device to perform anyexample embodiment of the method of the first aspect.

[0042] According to a sixth aspect, a device may comprise means for receiving, from a testing device, a configuration indicating that a multiple transmission and reception point operation is enabled with a two timing advance feature; means for detecting a first reference signal from a first transmission path and detecting a second reference signal from a second transmission path, wherein the first reference signal and the second reference signal are detected with a timing difference; means for determining that the timing difference between the first reference signal and the second reference signal is not greater than a first threshold; and when the timing difference is not greater than the first threshold, means for adjusting at least one of a first uplink transmission timing based on the detection of the first reference signal or a second uplink transmission timing based on the detection the second reference signal. The device may further comprise means for performing any example embodiment of the method of the first aspect.

[0043] According to a seventh aspect, a computer program may comprise instructions for causing a device to perform at least the following: transmit, to a device under test, a configuration indicating that a multiple transmission and reception point operation is enabled with a two timing advance feature; transmit, to the device under test, a first reference signal via a first transmission path and a second reference signal via a second transmission path, wherein the first reference signal and the second reference signal are transmitted with a relative delay such that a timing differencebetween the first reference signal and the second reference signal to be detected by the device under test is not greater than a first threshold; and monitor uplink transmissions of the device under test at the first transmission path and at the second transmission path to verify that the device under test is capable of performing one or more timing adjustments. The computer program may further comprise instructions for causing the device to perform any example embodiment of the method of the second aspect.

[0044] According to an eighth aspect, a device may comprise means for transmitting, to a device under test, a configuration indicating that a multiple transmission and reception point operation is enabled with a two timing advance feature; means for transmitting, to the device under test, a first reference signal via a first transmission path and a second reference signal via a second transmission path, wherein the first reference signal and the second reference signal are transmitted with a relative delay such that a timing difference between the first reference signal and the second reference signal to be detected by the device under test is not greater than a first threshold; and means for monitoring uplink transmissions of the device under test at the first transmission path and at the second transmission path to verify that the device under test is capable of performing one or more timing adjustments. The device may further comprise means for performing any example embodiment of the method of the second aspect.

[0045] Many of the attendant features will be more readily appreciated as they become better understood by reference to the following detailed descriptionconsidered in connection with the accompanying drawings. DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings, which are included to provide a further understanding of the example embodiments and constitute a part of this specification, illustrate example embodiments and together with the description help to explain the example embodiments. In the drawings:

[0047] FIG. 1 illustrates an example of a test system for over-the-air testing of two timing advance loops in multi-TRP scenario according to an example embodiment;

[0048] FIG. 2 illustrates an example of a set of devices configured to practice one or more example embodiments;

[0049] FIG. 3 illustrates an example procedure to verify support of two downlink reference timings of two timing advance loops according to an example embodiment;

[0050] FIG. 4 illustrates an example of a method for over-the-air test according to an example embodiment;

[0051] FIG. 5 illustrates an example of another method for over-the-air test according to an example embodiment.

[0052] Like references are used to designate like parts in the accompanying drawings. DETAILED DESCRIPTION

[0053] Reference will now be made in detail to example embodiments, examples of which are illustrated in the accompanying drawings. The detailed description provided below in connection with the appended drawings is intended as a description of the present examples andis not intended to represent the only forms in which the present examples may be constructed or utilized. The description sets forth the functions of the example and a possible sequence of operations for constructing and operating the example. However, the same or equivalent functions and sequences may be accomplished by different examples.

[0054] In 3GPP New Radio (NR) physical layer development, there is a concept of multiple transmission and reception point (multi-TRP or mTRP) for uplink (UL) transmission with two different operation modes focused on physical downlink shared channel (PDSCH), a single downlink control information (single-DCI) and multiple downlink control information (multi-DCI or mDCI). The single-DCI supports scenarios with ideal backhaul available among the TRPs, that for instance can make joint scheduling decisions. The multi-DCI supports scenarios with non-ideal backhaul among the TRPs, where each TRP may use its own DCI to schedule downlink data transmission independently. Multi-TRP schemes are also introduced for PDCCH (physical downlink control channel), PUSCH (physical uplink shared channel) and PUCCH (physical uplink control channel).

[0055] Further, in case of multi-TRP, two TA commands may be used for UL multi-DCI. Timing advance may refer to a special command (notification) from gNB to UE that enable the UE to adjust its uplink transmission. The Timing advance command may comprise a timing advance value and an indication to which TRP the TA value should be applied. The two TA feature may be designed for a scenario where a UE is transmitting in UL to two TRPs, where each TA command is used to control the UL timingfor both TRPs independently. When using two TAs, the UE may be configured for monitoring reference signals from each TRP. For multi-DCI based multi-TRP operation with two TAs, for each TAG (timing advance group), the uplink transmission timing may take place ^^^^+ ^^^_^^^^^^^ × ^^before downlink timing which is associated with UL / joint TCI state, wherein ^^^refers to a timing advance value, ^^^_^^^^^^refers to a fixed timing advance offset value and ^^refers to a basic timing unit. The UL / joint TCI states may be associated to one control resource set pool index corresponding to one TAG. For each TAG, there may be a reference timing which will relate to each TRP.

[0056] The UE may be required to transmit with an error less than or equal to ±Te (Te, timing error limit value) provided that the UE has received a synchronization signal block (SSB) in the last 160 ms for SCS (subcarrier spacing) smaller or equal to 240 kHz. The UE may be required to support means to adjust the UE timing autonomously, for example, to account for clock drift between UE and network, and also for small movements which can be adjusted without a need for network-initiated TA commands. The adjustments may be performed such that the timing error limit of ±Te (for example, based on Table 7.1.2-1 of 3GPP TS 38.133) is respected. The adjustments may be bounded by two variables:

[0057] Tq: the maximum amount of the magnitude of the timing change in one adjustment per 200 ms (of 100 ms for SCS ≥480 kHz).

[0058] Tp: the minimum aggregate adjustment per second.

[0059] In addition, timing advance adjustments mayneed to be performed with certain accuracy. One example for timing advance adjustment accuracy is specified in section 7.3.2.2 of 3GPP TS 38.133, which specify the timing error limits after TAC (timing advance command) is received by the UE. The UE may need to adjust the timing of its transmissions with a relative accuracy better than or equal to a UE timing advance adjustment accuracy requirement set for a UL sub carrier spacing.

[0060] In addition to UL timing accuracy, maximum receive timing difference (MRTD) and maximum transmit timing difference (MTTD) requirements may be considered. Both requirements may be specified for carrier aggregation and dual connectivity to take into account timing differences between cells. In those cases, MRTD / MTTD requirements may apply for serving cells operating in different center frequency. The requirements may have direct impact on the deployment, since they may limit the maximum distance between cells.

[0061] The MRTD / MTTD requirements may be also used for multi-TRP operation. A UE may have capabilities for supporting simultaneous transmission across multiple panels (STxMP) and also for supporting RTD>CP (receive timing difference > cyclic prefix). Considering possible UE capability combinations, the following table illustrates MRTD / MTTD requirements for multi-DCI multi- TRP operation with two TAs, wherein FR1 refers to a first frequency range and FR2 refers to a second frequency range: UE UE MRTD MTTD (μs) Margin supports supports (μs) (M1 / M2) (μs) RTD>CP STxMP FR1 Yes Yes 33 34.6 1.6 FR2 Yes Yes 8 8.5 0.5 FR1 Yes No 33 34.6 1.6FR2 Yes No 8 8.5 0.5 FR1 No Yes CP CP+1.6 1.6 FR2 No Yes CP CP+0.5 0.5 FR1 No No CP No No requirements requirements FR2 No No CP No No requirements requirements

[0062] The requirements impose that two TAs may be possible for a UE to perform two UL transmissions, each associated to a TAG, in a multi-TRP multi-DCI scenario when the transmit timing difference (TTD) between such two UL transmissions is within the limit, i.e., TTD≤MTTD. The TTD may depend on the following parameters:

[0063] RTD: Receive timing difference from two TRPs e.g., TRP1 and TRP2. The RTD may be computed / monitored at the UE. The RTD may depend mainly on a propagation delay difference of communication links toward the two TRPs. The RTD is generally not known at the networks side.

[0064] TAE: Transmit alignment error, which represents the transmit timing misalignment between the two TRPs.

[0065] TA1: Timing advance value from TRP1.

[0066] TA2: Timing advance value from TRP2.

[0067] It may be assumed that the RTD part of TTD is a significant contributor to the overall receive timing difference on the UE side.

[0068] An UL transmit timing error may be verified through radio resource management (RRM) test cases. For example, test equipment (TE) may be configured to behave as a gNB, and monitor a UE transmit timing to verify that the UL transmit timing error does not exceed thelimit specified by Te.

[0069] First, the test may comprise a setup and configuration phase, where the TE configures a PCell (primary cell) for the use in the test and starts transmitting SSBs. In this step, a device under test (DUT) (i.e., the UE) may be also configured with a SRS (sounding reference signal), which may be used by the TE for determining timing accuracy. During the test, the TE may be configured to act as a gNB, which means that it may be transmitting SSB and control signal messages, which are omitted in description.

[0070] Thereafter, the test may comprise an UL timing monitoring phase. The TE may be configured to monitor UL transmissions and verify if the UL transmissions meet a target requirement. For 5G NR, the target requirement may be that UL transmissions are within the limits ^^^^+ ^^^_^^^^^^^ × ^^− ^^and ^^^^+ ^^^_^^^^^^^ × ^^+ ^^, for example, as specified in section 7.1.2 of 3GPP TS 38.133.

[0071] The TE may be configured to adjust the DL path by applying a constant time shift to the DL path. The intention of the adjustment is to cause an abrupt change in the DL time reference for the DUT, and to observe the DUT behavior after that by the TE.

[0072] The DUT is expected to gradually adjust the UL transmit timing by applying adjustments within the time adjustment step Tq and the minimum aggregate adjustment rate Tp. The TE may monitor if the DUT is capable of applying the gradual timing adjustment.

[0073] The TE may monitor UL transmissions from the DUT and verify if the UL transmissions meet the target requirement (i.e., UL timing error is less than Te).After the DUT is capable of adjusting to the abrupt change in the timing of the DL path applied by the TE, it is expected that the DUT is again transmitting UL within

[0074] The RRM requirements about UE transmit timing (e.g., as defined in 7.1.2 of 3GPP TS 38.133), UE timer accuracy (e.g, as defined in 7.2.2 of 3GPP TS 38.133) and timing advance (e.g., as defined in 7.3.2 of 3GPP TS 38.133) may not be as such applied for two TAs. When the two TA feature is used, a UE may be configured to receive for example MAC CE (medium access control- control element) TA command(s) from a gNB that adjust one or more UL transmit timings for the UE. The TA command may be configured to inform the UE about relative adjustments. The two TA feature may be also referred to as two TA loops, as there may be a continuous set of TA commands from the gNB. Since test methods corresponding to such legacy RRM requirements were not designed for the two TA loop scenario, they may not be enough to be used to demonstrate compliance. An objective of this disclosure is to provide new test methods designed for the feature of two timing-advances.

[0075] An example embodiment may provide an over- the-air test method configured to verify that a behavior of a UE may be compliant with the two TA loops feature. The method may be used at least one of to verify that a UE configured with mDCI mTRP supports two DL reference timings (one DL-RS per control resource set pool index), adjusts UL transmit timings of each PUSCH according to received TA commands, and implements the support and adjustment functions within MRTD and MTTD.

[0076] According to an example embodiment, a testsystem may comprise two probes configured to emulate two different TRPs. The test system may further comprise a UE configured with two TA loops, where each probe is transmitting reference signals related to one of the TA loops. The reference signals may be transmitted by a gNB through each of the probes with a relative delay with each other. The relative delay may be adjusted per probe. The delay of at least one of the probes may be adapted during a test procedure to verify if the UE is capable of following reference signal of one TA group without impacting the UL timing accuracy of another TA group.

[0077] FIG. 1 illustrates an example of a test system 100 for over-the-air testing of two timing-advance loops in multi-TRP scenario according to an example embodiment.

[0078] The test system 100 may be in a controlled environment. The controlled environment may comprise, for example, an anechoic chamber 120. The controlled environment may also comprise, but is not limited to, a compact antenna test range chamber or a plane wave chamber.

[0079] The test system 100 may comprise a device under test (DUT) 102. The DUT may be configured to emulate a UE entity in a 3GPP system, such as LTE or 5G- NR. The DUT 102 may be placed on a non-reflective surface, such as a Styrofoam table 122. The DUT 102 may be positioned at a distance that fulfils the far-field criteria 2D2 / λ, wherein D refers to the largest dimension of the antenna under test and λ refers to a wavelength of a wave.

[0080] The test system 100 may comprise at least twoantenna arrays 112, 114. Each of the antenna arrays 112, 114 may be configured to emulate different TRPs. For example, the first antenna array 112 may be configured to emulate a first transmission reception point (TRP1). The second antenna array 114 may be configured to emulate a second transmission reception point (TRP2). The test system 100 may further comprise wireless communication links configured to couple the DUT 102 to the antenna arrays 112, 114. The antenna arrays 112, 114 may be configured to transmit downlink beams 116 towards the DUT 102. The DUT 102 may be configured to transmit uplink beams 118 towards each of the antenna arrays 112, 114. In general, communication between the DUT 102 and the first antenna array 112 may be performed via first transmission path, and communication between the DUT 102 and the second antenna array 114 may be performed via second transmission path. A transmission path may refer to a transmission channel between two nodes of a network that a data communication follows. The transmission path can refer to the physical cabling that connects the nodes on a network or to a radio link.

[0081] The test system 100 may comprise a testing device 104. The antenna arrays 112, 114 may be coupled to the testing device 104. A testing device may be also referred to as a test equipment (TE). The testing device 104 may be configured to emulate a gNB entity 106. The testing device 104 may be configured to transmit reference signals to the DUT 102 via the antenna arrays 112, 114. The testing device 104 may be configured to configure additional delays110 and ^^108 for the respective reference signals sent via different antenna arrays 112, 114.

[0082] FIG. 2 illustrates an example of a set of devices 200, 212 configured to practice one or more example embodiments.

[0083] The device 200 may be a DUT (e.g., the DUT 102) configured to emulate functionalities of a node or an element in a communications network or associated with such a network, such as a UE, a mobile station, a mobile device, a stationary device, an IoT device, or the like. Although the device 200 is illustrated as a single device it is appreciated that, wherever applicable, functions of device 200 may be distributed to a plurality of devices.

[0084] The device 200 may comprise at least one processor 202. The at least one processor 202 may comprise, for example, one or more of various processing devices, such as for example a co-processor, a microprocessor, a controller, a digital signal processor (DSP), a processing circuitry with or without an accompanying DSP, or various other processing devices including integrated circuits such as, for example, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a microcontroller unit (MCU), a hardware accelerator, a special-purpose computer chip, or the like.

[0085] The device 200 may further comprise at least one memory 204. The memory 204 may be configured to store, for example, computer program code 206 or the like, for example operating system software and application software. The memory 204 may comprise one or more volatile memory devices, one or more non- volatile memory devices, and / or a combination thereof. For example, the memory 204 may be embodied as magneticstorage devices (such as hard disk drives, magnetic tapes, etc.), optical magnetic storage devices, or semiconductor memories (such as mask ROM, PROM (programmable ROM), EPROM (erasable PROM), flash ROM, RAM (random access memory), etc.).

[0086] The device 200 may further comprise one or more communication interfaces 208 configured to enable device 200 to transmit information to other devices, such as to the device 212. The communication interface 208 may be further configured to enable the device 200 to receive information from other devices, such as from the device 212. The communication interface 208 may be configured to provide at least one wireless radio connection, such as for example a 3GPP mobile broadband connection (e.g., 3G, 4G, 5G, or beyond). However, the communication interface 208 may be configured to provide one or more other type of connections, for example a wireless local area network (WLAN) connection such as for example standardized by IEEE 802.11 series or Wi-Fi alliance; a short range wireless network connection such as for example a Bluetooth, NFC (near-field communication), or RFID connection; a wired connection such as for example a local area network (LAN) connection, a universal serial bus (USB) connection or an optical network connection, or the like; or a wired Internet connection. The communication interface 208 may comprise, or be configured to be coupled to, at least one antenna to transmit and / or receive radio frequency signals. One or more of the various types of connections may be also implemented as separate communication interfaces, which may be coupled or configured to be coupled to a plurality of antennas.

[0087] The device 200 may further comprise a user interface 210 comprising an input device and / or an output device. The input device may take various forms such a keyboard, a touch screen, or one or more embedded control buttons. The output device may for example comprise a display, a speaker, a vibration motor, or the like.

[0088] The device 212 may be a testing device (e.g., the testing device 104) configured to emulate functionalities of a network, a core network element, or an element in a communications network or associated with such a network, such as gNB. Although the device 212 is illustrated as a single device it is appreciated that, wherever applicable, functions of device 212 may be distributed to a plurality of devices.

[0089] The device 212 may comprise at least one processor 214. The at least one processor 214 may comprise, for example, one or more of various processing devices, such as for example a co-processor, a microprocessor, a controller, a digital signal processor (DSP), a processing circuitry with or without an accompanying DSP, or various other processing devices including integrated circuits such as, for example, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a microcontroller unit (MCU), a hardware accelerator, a special-purpose computer chip, or the like.

[0090] The device 212 may further comprise at least one memory 216. The memory 216 may be configured to store, for example, computer program code 218 or the like, for example operating system software and application software. The memory 216 may comprise oneor more volatile memory devices, one or more non- volatile memory devices, and / or a combination thereof. For example, the memory 216 may be embodied as magnetic storage devices (such as hard disk drives, magnetic tapes, etc.), optical magnetic storage devices, or semiconductor memories (such as mask ROM, PROM (programmable ROM), EPROM (erasable PROM), flash ROM, RAM (random access memory), etc.).

[0091] The device 212 may further comprise one or more communication interfaces 220 configured to enable device 212 to transmit information to other devices, such as to the device 200. The communication interface 220 may be further configured to enable the device 212 to receive information from other devices, such as from the device 200. The communication interface 220 may be configured to provide at least one wireless radio connection, such as for example a 3GPP mobile broadband connection (e.g., 3G, 4G, 5G, or beyond). However, the communication interface 220 may be configured to provide one or more other type of connections, for example a wireless local area network (WLAN) connection such as for example standardized by IEEE 802.11 series or Wi-Fi alliance; a short range wireless network connection such as for example a Bluetooth, NFC (near-field communication), or RFID connection; a wired connection such as for example a local area network (LAN) connection, a universal serial bus (USB) connection or an optical network connection, or the like; or a wired Internet connection. The communication interface 220 may comprise, or be configured to be coupled to, at least one antenna to transmit and / or receive radio frequency signals. One or more of the various types of connectionsmay be also implemented as separate communication interfaces, which may be coupled or configured to be coupled to a plurality of antennas.

[0092] The device 212 may further comprise a user interface 222 comprising an input device and / or an output device. The input device may take various forms such a keyboard, a touch screen, or one or more embedded control buttons. The output device may for example comprise a display, a speaker, a vibration motor, or the like.

[0093] When a device (e.g., the device 200 and / or the device 212) is configured to implement some functionality, some component and / or components of the device, such as for example at least one processor and / or at least one memory, may be configured to implement this functionality. Furthermore, when the at least one processor is configured to implement some functionality, this functionality may be implemented using instructions comprised, for example, in the at least one memory.

[0094] For example, the device 200 may be configured to receive, from the device 212, a configuration indicating that a multiple transmission and reception point operation is enabled with two timing advances; detect a first reference signal from a first transmission path and detect a second reference signal from a second transmission path, wherein the first reference signal and the second reference signal are detected with a relative delay with each other; determine that a timing difference between the first reference signal and the second reference signal is not greater than a threshold; and when the timing differenceis not greater than the threshold, adjust at least one of a first uplink transmission timing based on the detection of the first reference signal or a second uplink transmission timing based on the detection the second reference signal.

[0095] For example, the device 212 may be configured to transmit, to the device 200, a configuration indicating that a multiple transmission and reception point operation is enabled with two timing advances; transmit a first reference signal via a first transmission path and a second reference signal via a second transmission path to the device 200, wherein the first reference signal and the second reference signal are transmitted with a relative delay with each other such that a timing difference between the first reference signal and the second reference signal to be detected by the device 200 is not greater than a threshold; and monitor uplink transmissions from the device 200 to verify that the device 200 is capable of adjusting at least one of a first uplink transmission timing based on the first reference signal or a second uplink transmission timing based on the second reference signal.

[0096] The functionality described herein may be performed, at least in part, by one or more computer program product components such as software components. According to an embodiment, a device (e.g., the device 200 and / or the device 212) comprises a processor or processor circuitry, such as for example a microcontroller, configured by the program code when executed to execute the embodiments of the operations and functionality described. Alternatively, or inaddition, the functionality described herein can be performed, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs), application-specific Integrated Circuits (ASICs), application-specific Standard Products (ASSPs), System- on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), Graphics Processing Units (GPUs).

[0097] According to an example embodiment, a device (e.g., the device 200 and / or the device 212) may comprise means for performing at least one method described herein. In one example, the means comprises at least one processor, and at least one memory including program code configured to, when executed by the at least one processor, cause the device to perform the method.

[0098] FIG. 3 illustrates an example of a procedure to verify support of two downlink reference timings of two timing advance loops according to an example embodiment. The procedure may be performed, for example, with the test system 100 illustrated in FIG. 1. The procedure may comprise performing first an initial configuration 300, then performing a test for two DL reference timings 302, and lastly performing a test for two TA loops delay and accuracy 304.

[0099] At 306, a DUT and two TRPs may be deployed in an anechoic chamber, such as the DUT 102 and TRP1, TPR2 emulated by the antenna arrays 112, 114. A reference signal used by the DUT as downlink reference timing for UL transmission may be configured to be a first synchronization signal block (SSB1) for TRP1 and asecond synchronization signal block (SSB2) for TRP2. The DUT and the antenna arrays 112, 114 may be positioned such that there are same distances between the DUT and the TPR1 and the DUT and the TPR2. The DUT may be connected to the TRP1 and to the TRP2 with wireless communication links, i.e., via a first transmission path and a second transmission path. Actual propagation delays between the DUT and the two TRPs may be assumed approximately the same.

[0100] During the initial configuration 300, at 308, a testing device (e.g., the testing device 104) may be configured to determine MRDT and MTTD requirements for the DUT. The MRDT and MTTD requirements may depend on the DUT capabilities.

[0101] At 310, the testing device may be configured to introduce additional delays for the reference signals. For example, the testing device may configure a delayfor SSB1 sent by TRP1 and a delay ^^for SSB2 sent by TRP2. The testing device may be configured to control the additional delays. The testing device may be configured to change the additional delays during the test procedure.

[0102] For example, for the initial configuration, the testing device may configure= ^^= 0, such that the propagation delays from the two TRPs experienced by the DUT may be approximately the same (RTD≈0), and such that RTD<MRTD. Another example for the initial configuration could be configuring= ^^and ^^= −^^, with 2^^<MRTD.

[0103] An advantage of the second example for initial configuration (^^= ^^and ^^= −^^) when compared to thefirst example (^^= ^^= 0) is that, assuming that in successive measurements the difference betweenand ^^will be increased, a faster test can be performed to reach the MRTD limit. The delay(s) may be adjusted by the testing device during the test such that the MRTD limit is reached in order to test that the DUT can implement the two TA feature under the requirement for the two TAs, i.e., RTD<MRTD.

[0104] At 312, the testing device may be configured to start transmitting the SSB1 and the SSB2. The UL frame transmission toward each TRP may take place within ^^^^+ ^^^_^^^^^^^ × ^^− ^^and ^^^^+ ^^^_^^^^^^^ × ^^+ ^^before reception of a first detected path (in time) of the corresponding DL frame. ^^^for PRACH (physical random access channel) may be defined as 0.

[0105] At 314, the testing device may be configured to configure the DUT with multi-DCI and two TA loops. The testing device may be further configured to indicate the DUT with two TCI states. The first TCI state (TCI- state 1) may comprise a quasi co-location (QCL) with the SSB1 as the reference signal. The second TCI state (TCI- state 2) may comprise a quasi co-location with SSB2 as the reference signal. Other types of reference signal may be configured as well, such as CSI-RS (channel state information reference signal). Although multi-DCI may be used in this step, the DUT may be also configured with a single-DCI and two TA loops.

[0106] During the test for two DL reference timing 302, at 316, the testing device may be configured to adjust the additional delay for SSB1 and ^^for SSB2. For example, the testing device may be configured not to vary the delay and to adjust the delay ^^= ^^^^^,with margin ^ ≤ 1. The testing device may be configured to perform the adjustments such that it may be ensured that MRTD and MTTD are not violated for the DUT. The margin ^ can be computed by the testing device considering at least ^^and accuracy of the testing device in settingand ^^. Alternatively, the testing device may be configured not to vary the delay ^^and to configure the delay= ^^^^^. Here, initial values of the delays may have been= ^^= 0.

[0107] Alternatively, the testing device may be configured to adjust the additional delays by selecting ^^= ^^^^^⁄ 2 and ^^= −^^^^^⁄ 2. An advantage of the procedure using two controllable time delays for TRP1 and TRP2 (e.g.,and ^^= −^^^^^⁄2) by the testing device with regard to the procedure using just one controllable delay (e.g., adjusting one ofor ^^to ^^^^^) is a reduction in the overall test duration. In fact, for a given time adjustment step Tq<<MRTD, with two additional delays it takes approximately half of the time to span a RTD between 0 and MRTD.

[0108] Depending on a time adjustment step Tq, the testing device may need to repeat the additional delay adjustments several times before having the RTD to reach the MRTD. The DUT is expected to gradually adjust the UL transmit timing, for example, by applying adjustments with maximum autonomous time adjustment step Tq and minimum aggregate adjustment rate Tp (e.g., as specified in 7.1.2.1 of TS 38.133).

[0109] In case the delay ^^was not adjusted and the delaywas adjusted (e.g., ^^was kept at 0 andwas adjusted to ^^^^^ by the testing device), the DUT isexpected to adjust the UL transmit timing of the UL transmission toward TRP1. In case the delay ^^was not adjusted and the delay ^^was adjusted (e.g., ^^was kept at 0 and ^^was adjusted to ^^^^^ by the testing device), the DUT is expected to adjust the UL transmit timing of the UL transmission toward TRP2. In case both delays ^^and ^^was adjusted by the testing device, the DUT is expected to adjust the UL transmit timing of both UL transmissions toward TRP1 and TRP2.

[0110] At 318, the testing device may be configured to monitor if the DUT is capable of applying the gradual timing adjustment for the expected UL transmission(s). For example, the testing device may be configured to monitor the transmit timing of signals transmitted by the DUT by measuring UL receipt timing at TRP1 and / or TRP2.

[0111] At 320, the testing device may be configured to verify that the DUT adjusts the UL transmit timing of the UL transmit toward TRPii=1,2.

[0112] At 322, the testing device may be configured to verify that the DUT does not adjust the UL transmit timing of the UL transmission toward TRPj if ^^= 0, j=1,2.

[0113] During the test for two TA loops delay and accuracy 304, at 324, the testing device may be configured to send a MAC-CE TA command configured to notify ^^^^for TCI-state1 / SSB1 in slot n. The testing device may be configured to select a value of ^^^^such that MRTD and MTTD may not be violated for the DUT. For example, the MAC-CE TA command could be chosen such that |^^− ^^+ ^^^^| < ^MTTD, with margin ^ ≤ 1. Similarly tooperation 316, margin ^ can as well be assumed depending on at least the UL transmit timing accuracy ^^or the requirements for timing advance adjustment error.

[0114] The DUT may be configured to adjust the UL transmit timing of the UL transmission toward TRP1 at time slot n+k+1. The value of k may be defined, for example, in accordance with section 4.2 of 3GPP TS 38.213. The DUT may be further configured not to vary the UL transmit timing of the UL transmission toward TRP2 at the same or next time slot dedicated to TRP2 transmission after slot n+k+1.

[0115] At 326, the testing device may be configured to monitor if the DUT is capable of adjusting the UL transmit timing of UL transmission toward TRP1 exactly at the time slot n+k+1 (while not varying the UL transmit timing of the UL transmission toward TRP2 on the same / next time slot). For example, the testing device may be configured to monitor the DUT transmit timing by measuring UL receipt timing at the TRP1 and / or the TRP2.

[0116] At 328, the testing device may be configured to verify that the DUT adjusts the UL transmit timing of the UL transmission toward TRP1 in the slot n+k+1 within configured limits.

[0117] At 330, the testing device may be configured to verify that the DUT does not adjust the UL transmit timing of the UL transmission toward TRP2.

[0118] During the described example for a test for two TA loops delay and accuracy 304, a timing advance command is sent only for TRP1. However, similar tests can be designed, wherein either a timing advance command is sent only for TRP2 or one or more timing advance commands are sent for both TRP1 and TRP2 in the sameslot.

[0119] FIG. 4 illustrates an example of a method 400 for over-the-air test according to an example embodiment. The method may be performed, for example, by a device under test such as the device 200.

[0120] At 402, the method may comprise receiving, from a testing device, a configuration indicating that a multiple transmission and reception point operation is enabled with a two timing-advance feature. The testing device may comprise, for example, the device 212.

[0121] At 404, the method may comprise detecting a first reference signal from a first transmission path and detecting a second reference signal from a second transmission path, wherein the first reference signal and the second reference signal are detected with a timing difference. For example, the configuration received at 402 may comprise TCI-state information associated with the first transmission path and the second transmission path. The TCI-state information may comprise, for example, a first QCL with the first reference signal (e.g., a first SSB) to be used for the first uplink transmission and a second QCL with the second reference signal (e.g. a second SSB) to be used for the second uplink transmission.

[0122] At 406, the method may comprise determining that the timing difference between the first reference signal and the second reference signal is not greater than a first threshold. The first threshold may be based on, for example, a maximum reception timing difference requirement for the device 200.

[0123] After determining that the time difference isnot greater than the threshold, the method may comprise, at 408, adjusting at least one of a first uplink transmission timing based on the detection of the first reference signal or a second uplink transmission timing based on the detection the second reference signal. The adjusting may comprise performing gradual reduction or increase of at least one of the first UL transmission timing or the second UL transmission timing by applying a plurality of adjustments, depending on which one of the first or the second reference signal is delayed, or if both of the reference signals are delayed. The plurality of adjustments may be performed autonomously by the device 200. The gradual reduction and / or gradual increase of UL timing may be also referred to as a gradual adaptation of UL timing. The adjustment may further comprise applying a timing advance value received from the testing device to at least one of the uplink transmission timings. If one of the reference signals is not delayed, or no timing advance value is received for the reference signal, the method may comprise keeping the associated UL transmission timing unchanged.

[0124] FIG. 5 illustrates an example of another method 500 for an over-the-air test according to an example embodiment. The method may be performed, for example, by a testing device such as the device 212.

[0125] At 502, the method may comprise transmitting, to a device under test, a configuration indicating that a multiple transmission and reception point operation is enabled with a two timing-advance feature. The device under test may comprise, for example, the device 200.

[0126] At 504, the method may comprise transmittinga first reference signal via a first transmission path and a second reference signal via a second transmission path to the device under test, wherein the first reference signal and the second reference signal are transmitted with a relative delay. The relative delay may be determined, by the testing device, such that a timing difference between the first reference signal and the second reference signal to be detected by the device under test is not greater than a first threshold. The first threshold may be based on, for example, a maximum reception timing difference requirement of the device under test. The threshold may be further based on at least one of a UL transmission timing error limit of the device under test or an accuracy for setting the relative delay by the testing device. The relative delay may be based on at least one of a first delay set by the testing device for the first reference signal or a second delay set by the testing device for the second reference signal. The testing device may be configured to vary the first delay for transmitted first reference signals while keeping the second delay constant, vary the second delay for transmitted second reference signals while keeping the first delay constant, or to vary both the first delay and the second delay. The adjusted relative delay may be caused to vary such that the timing difference has values approximately between zero and the MRTD. The first reference signal may comprise a first synchronization signal block. The second reference signal may comprise a second synchronization signal block.

[0127] At 506, the method may comprise monitoring uplink transmissions to verify that the device undertest is capable of performing one or more timing adjustments, such as adjusting at least one of a first uplink transmission timing based on the first reference signal or a second uplink transmission timing based on the second reference signal.

[0128] For example, the method may comprise verifying that the device under test was able to perform gradual adaptations on at least one of the first uplink transmission timing or the second uplink transmission timing, depending on the relative delay (e.g., that first uplink transmission timing was adjusted when the first reference signal was transmitted with first delay while the second UL transmission timing is kept unchanged when the second reference signal was transmitted without a delay, i.e., the second delay = 0). The verification may be performed by monitoring UL reception timing at the first transmission path and the second transmission path.

[0129] The method may further comprise verifying, by measuring UL reception timing at the first transmission path and the second transmission path, that the device under test was able to adjust at least one the first UL transmission timing or the second UL transmission timing according to a TAC sent by the testing device. If the TAC notified a TA value to be applied for only one of the first UL transmission timing or the second UL transmission timing, the method may comprise verifying that DUT does not adjust the UL transmission timing towards a transmission path not being indicated by the TAC.

[0130] Further features of the methods directly result from the functionalities and parameters of thedevices, as described in the appended claims and throughout the specification and are therefore not repeated here. It is noted that one or more operations of the method may be performed in different order.

[0131] A device, for example a testing device or a device under test, may be configured to perform or cause performance of any aspect of the method(s) described herein. Further, a computer program may comprise instructions for causing, when executed, a device to perform any aspect of the method(s) described herein. Further, a device may comprise means for performing any aspect of the method(s) described herein. According to an example embodiment, the means comprises at least one processor, and memory including program code, the at one memory and the program code configured to, when executed by the at least one processor, cause performance of any aspect of the method(s).

[0132] Any range or device value given herein may be extended or altered without losing the effect sought. Also, any embodiment may be combined with another embodiment unless explicitly disallowed.

[0133] Although the subject matter has been described in language specific to structural features and / or acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as examples of implementing the claims and other equivalent features and acts are intended to be within the scope of the claims.

[0134] It will be understood that the benefits and advantages described above may relate to one embodimentor may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages. It will further be understood that reference to 'an' item may refer to one or more of those items.

[0135] Although subjects may be referred to as ‘first’ or ‘second’ subjects, this does not necessarily indicate any order or importance of the subjects. Instead, such attributes may be used solely for the purpose of making a difference between subjects.

[0136] The operations of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate. Additionally, individual blocks may be deleted from any of the methods without departing from the scope of the subject matter described herein. Aspects of any of the embodiments described above may be combined with aspects of any of the other embodiments described to form further embodiments without losing the effect sought.

[0137] The term 'comprising' is used herein to mean including the method, blocks, or elements identified, but that such blocks or elements do not comprise an exclusive list and a method or apparatus may contain additional blocks or elements.

[0138] As used in this application, the term ‘circuitry’ may refer to one or more or all of the following: (a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and (b) combinations of hardware circuits and software, such as (as applicable):(i) a combination of analog and / or digital hardware circuit(s) withsoftware / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation. This definition of circuitry applies to all uses of this term in this application, including in any claims.

[0139] As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0140] It will be understood that the above description is given by way of example only and that various modifications may be made by those skilled in the art. The above specification, examples and data provide a complete description of the structure and use of exemplary embodiments. Although various embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art couldmake numerous alterations to the disclosed embodiments without departing from scope of this specification.

Claims

CLAIMS 1. A method carried out by a device under test, comprising: receiving, from a testing device, a configuration indicating that a multiple transmission and reception point operation is enabled with a two timing-advance feature; detecting a first reference signal from a first transmission path and detecting a second reference signal from a second transmission path, wherein the first reference signal and the second reference signal are detected with a timing difference; determining that the timing difference between the first reference signal and the second reference signal is not greater than a first threshold; and when the timing difference is not greater than the first threshold, adjusting at least one of a first uplink transmission timing based on the detection of the first reference signal or a second uplink transmission timing based on the detection the second reference signal.

2. The method of claim 1, wherein the adjustment comprises at least one of performing a gradual adaptation by applying a plurality of autonomous adjustments or applying an adjustment based on a timing advance command received from the testing device.

3. The method of claim 1 or 2, wherein the method comprises:detecting that the timing difference is caused by a delay of one of the first reference signal or the second reference signal; and performing a gradual adaptation of one of the first uplink transmission timing based on the delay detected for the first reference signal or the second uplink transmission timing based on the delay detected for the second reference signal by applying a plurality of autonomous adjustments.

4. The method of claim 1 or 2, wherein the method comprises: detecting that the timing difference is caused by a first delay of the first reference signal and a second delay of the second reference signal; and performing gradual adaptations of both the first uplink transmission timing and the second uplink transmission timing by applying a plurality of autonomous adjustments in response to the detected delays.

5. The method of any preceding claim, comprising: receiving, from the testing device, a timing advance command notifying a timing advance value for the first transmission path; determining that a timing difference between the first uplink transmission and the second uplink transmission is not greater than a second threshold after applying the timing advance command; and if the second threshold is not exceeded, adjusting the first uplink transmission timing according to thetiming advance command while the second uplink transmission timing is kept unchanged.

6. The method of any preceding claim, comprising: receiving, from the testing device, one or more timing advance commands notifying a timing advance value for the first transmission path and a timing advance value for the second transmission path; determining that a timing difference between the first uplink transmission and the second uplink transmission is not greater than a second threshold after applying the one or more timing advance commands; and if the second threshold is not exceeded, adjusting both the first uplink transmission timing and the second uplink transmission timing according to the one or more timing advance commands.

7. The method of any of claims 1 to 6, wherein the reference signal comprises a synchronization signal block or a channel state information reference signal.

8. The method of any of claims 1 to 7, wherein the configuration indicates two transmission configuration indicator states, the first transmission configuration indicator state comprising a first quasi co-location with the first reference signal to be used for the first uplink transmission and the second transmission configuration indicator state comprising a second quasi co-location with the second reference signal to be used for the second uplink transmission.

9. A method carried out by a testing device, comprising: transmitting, to a device under test, a configuration indicating that a multiple transmission and reception point operation is enabled with a two timing-advance feature; transmitting, to the device under test, a first reference signal via a first transmission path and a second reference signal via a second transmission path, wherein the first reference signal and the second reference signal are transmitted with a relative delay such that a timing difference between the first reference signal and the second reference signal to be detected by the device under test is not greater than a first threshold; and monitoring uplink transmissions of the device under test at the first transmission path and at the second transmission path to verify that the device under test is capable of performing one or more timing adjustments.

10. The method of claim 9, wherein the monitoring comprises verifying that the device under test is capable of applying at least one of a gradual adaptation of uplink transmission timing or a timing advance command for expected uplink transmission without impacting accuracy of other uplink transmissions.

11. The method of claim 9 or 10, wherein the relative delay is caused by transmitting the first reference signal with a delay and transmitting the second reference signal without a delay, and the method further comprises:adjusting the delay such that the timing difference of consecutive transmissions of the first reference signal and the second reference signal to be detected by the device under test is increased until the first threshold is met; and verifying that the device under test performed a gradual adaptation of the first uplink transmission timing in response to the relative delay while maintaining the second uplink transmission timing.

12. The method of claim 9 or 10, wherein the relative delay is caused by transmitting the first reference signal with a first delay and the second reference signal with a second delay, and the method further comprises: adjusting both the first delay and the second delay such that the timing difference of consecutive transmissions of the first reference signal and the second reference signal to be detected by the device under test is increased until the first threshold is met; and verifying that the device under test performed gradual adaptation of both the first uplink transmission timing and the second uplink transmission timing in response to the first delay and the second delay.

13. The method of claims 11 or 12, wherein at least one of the first delay or the second delay is determined based on at least one of the first threshold, a timing error limit of the device under test or an accuracy in setting at least one of the first delay or the second delay.

14. The method of any of claims 9 to 13, comprising: determining a timing advance value for the first transmission path, wherein the timing advance value is determined such that a timing difference between the first uplink transmission timing and the second uplink transmission timing is not greater than a second threshold; transmitting, to the device under test, a timing advance command notifying the determined timing advance value for the first transmission path; and monitoring that the device under test is capable of adjusting the first uplink transmission timing according to the timing advance command while the second uplink transmission timing is unchanged.

15. The method of any claims 9 to 13, comprising: determining a timing advance value for the first transmission path and for the second transmission path, wherein the timing advance values are determined such that a timing difference between the first uplink transmission timing and the second uplink transmission timing is not greater than a second threshold; transmitting, to the device under test, one or more timing advance commands notifying the timing advance value for the first transmission path and the timing advance value for the second transmission path; and monitoring that the device under test is capable of adjusting the first uplink transmission timing and the second uplink transmission timing according to the one or more timing advance commands.

16. The method of claim 14 or 15, wherein the timing advance value is further determined based on at least one of the first threshold, the relative delay, or the timing error limit.

17. The method of any of claims 9 to 16, wherein the reference signal comprises a synchronization signal block or a channel state information reference signal.

18. The method of any of claims 9 to 17, wherein the configuration indicates two transmission configuration indicator states, the first transmission configuration indicator state comprising a first quasi co-location with the first reference signal to be used for the first uplink transmission and the second transmission configuration indicator state comprising a second quasi co-location with the second reference signal to be used for the second uplink transmission.

19. A device (200), comprising means for carrying out at least the method of any of claims 1 to 8.

20. A device (212), comprising means for carrying out at least the method of any of claims 9 to 18.

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