WO2019213914A1

WO2019213914A1 - Sounding reference signal transmission

Info

Publication number: WO2019213914A1
Application number: PCT/CN2018/086375
Authority: WO
Inventors: Yukai GAO; Gang Wang
Original assignee: Nec Corporation
Priority date: 2018-05-10
Filing date: 2018-05-10
Publication date: 2019-11-14
Also published as: JP2021530123A; JP7188455B2

Abstract

Embodiments of the present disclosure relate to methods, devices and computer readable mediums for sounding reference signal (SRS) transmission. In example embodiments, a method implemented at a terminal device is provided. According to the method, the terminal device receives Downlink Control Information (DCI) from a network device. In response to the DCI including a first trigger for an aperiodic SRS and the aperiodic SRS being associated with a reference signal (RS), the terminal device receives the RS from the network device. The terminal device further determines precoding information related to the aperiodic SRS based on the received RS. The terminal device then transmits the aperiodic SRS to the network device based on the precoding information.

Description

SOUNDING REFERENCE SIGNAL TRANSMISSION

TECHNICAL FIELD

Embodiments of the present disclosure generally relate to the field of telecommunication, and in particular, to methods, devices and computer readable mediums for sounding reference signal (SRS) transmission.

BACKGROUND

With the development of communication technologies, multiple types of services or traffic have been proposed, for example, enhanced mobile broadband (eMBB) generally requiring high data rate, massive machine type communication (mMTC) typically requiring long battery lifetime, and ultra-reliable and low latency communication (URLLC) . Meanwhile, multi-antenna schemes, such as beam management, reference signal (RS) transmission, and so on, are studied for new radio access (NR) .

In NR, it is supported to indicate a downlink (DL) measurement RS (for example, Channel State Information-Reference Signal (CSI-RS) ) for a terminal device to determine uplink (UL) candidate pre-coders for an aperiodic SRS (AP-SRS) via Downlink Control Information (DCI) . It is also supported to indicate a DL measurement RS (for example, CSI-RS) for a terminal device to determine UL candidate pre-coders for a periodic SRS (P-SRS) or a semi-persistent SRS (SP-SRS) via higher layer signaling. An AP-SRS can be associated with an aperiodic CSI-RS (AP-CSI-RS) . The AP-CSI-RS can be transmitted in the same slot as the DCI containing a trigger of the AP-SRS. An SRS (such as, AP-SRS, P-SRS or SP-SRS) can be associated with a periodic CSI-RS (P-CSI-RS) or a semi-persistent CSI-RS (SP-CSI-RS) .

If an AP-CSI-RS is associated with an AP-SRS and the trigger for the AP-SRS is included in an SRS request field in the DCI, the AP-CSI-RS can be transmitted in the same slot as the DCI. However, if the SRS request field indicates that no A-SRS is triggered, how to proceed with the CSI-RS transmission has not been specified. Moreover, if a P-CSI-RS or SP-CSI-RS is associated with the AP-SRS, how to proceed with the AP-SRS transmission and the P-CSI-RS or SP-CSI-RS transmission has not been specified.

SUMMARY

In general, example embodiments of the present disclosure provide methods, devices and computer readable mediums for SRS transmission.

In a first aspect, there is provided a method implemented at a terminal device. According to the method, the terminal device receives Downlink Control Information (DCI) from a network device. In response to the DCI including a first trigger for an aperiodic SRS and the aperiodic SRS being associated with a reference signal (RS) , the terminal device receives the RS from the network device. The terminal device further determines precoding information related to the aperiodic SRS based on the received RS. The terminal device then transmits the aperiodic SRS to the network device based on the precoding information.

In a second aspect, there is provided a method implemented at a network device. According to the method, the network device transmits Downlink Control Information (DCI) to a terminal device. In response to the DCI including a first trigger for an aperiodic SRS and the aperiodic SRS being associated with a reference signal (RS) , the network device transmits the RS to the terminal device. The network device then receives the aperiodic SRS from the terminal device. The aperiodic SRS is transmitted by the terminal device at least based on the RS.

In a third aspect, there is provided a device. The device comprises a processor and a memory coupled to the processor. The memory stores instructions that when executed by the processor, cause the device to perform actions. The actions include: receiving Downlink Control Information (DCI) from a network device; in response to the DCI including a first trigger for an aperiodic SRS and the aperiodic SRS being associated with a reference signal (RS) , receiving the RS from the network device; determining, based on the received RS, precoding information related to the aperiodic SRS; and transmitting, based on the precoding information, the aperiodic SRS to the network device.

In a fourth aspect, there is provided a device. The device comprises a processor and a memory coupled to the processor. The memory stores instructions that when executed by the processor, cause the device to perform actions. The actions include: transmitting Downlink Control Information (DCI) to a terminal device; in response to the DCI including a first trigger for an aperiodic SRS and the aperiodic SRS being associated with a reference signal (RS) , transmitting the RS to the terminal device; and receiving the aperiodic SRS from the terminal device, the aperiodic SRS being transmitted by the terminal device at least based on the RS.

In a fifth aspect, there is provided a computer readable medium having instructions stored thereon. The instructions, when executed on at least one processor, cause the at least one processor to carry out the method according to the first aspect of the present disclosure.

In a sixth aspect, there is provided a computer readable medium having instructions stored thereon. The instructions, when executed on at least one processor, cause the at least one processor to carry out the method according to the second aspect of the present disclosure.

In a seventh aspect, there is provided a computer program product that is tangibly stored on a computer readable storage medium. The computer program product includes instructions which, when executed on at least one processor, cause the at least one processor to carry out the method according to the first aspect or the second aspect of the present disclosure.

Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Through the more detailed description of some embodiments of the present disclosure in the accompanying drawings, the above and other objects, features and advantages of the present disclosure will become more apparent, wherein:

Fig. 1 is a block diagram of a communication environment in which embodiments of the present disclosure can be implemented;

Fig. 2 shows a process for SRS transmission according to some implementations of the present disclosure;

Figs. 3A and 3B show examples of some embodiments of the present disclosure;

Fig. 4 shows an example of some embodiments of the present disclosure;

Fig. 5 shows an example of some embodiments of the present disclosure;

Fig. 6 shows a flowchart of an example method for SRS transmission according to some embodiments of the present disclosure;

Fig. 7 shows a flowchart of an example method for SRS transmission according to some embodiments of the present disclosure; and

Fig. 8 is a simplified block diagram of a device that is suitable for implementing embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar element.

DETAILED DESCRIPTION

Principle of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitations as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

As used herein, the term “network device” or “base station” (BS) refers to a device which is capable of providing or hosting a cell or coverage where terminal devices can communicate. Examples of a network device include, but not limited to, a Node B (NodeB or NB) , an Evolved NodeB (eNodeB or eNB) , a next generation NodeB (gNB) , a Transmission Reception Point (TRP) , a Remote Radio Unit (RRU) , a radio head (RH) , a remote radio head (RRH) , a low power node such as a femto node, a pico node, and the like. For the purpose of discussion, in the following, some embodiments will be described with reference to gNB as examples of the network device.

As used herein, the term “terminal device” refers to any device having wireless or wired communication capabilities. Examples of the terminal device include, but not limited to, user equipment (UE) , personal computers, desktops, mobile phones, cellular phones, smart phones, personal digital assistants (PDAs) , portable computers, image capture devices such as digital cameras, gaming devices, music storage and playback appliances, or Internet appliances enabling wireless or wired Internet access and browsing and the like. For the purpose of discussion, in the following, some embodiments will be described with reference to UE as examples of the terminal device.

As used herein, the singular forms “a” , “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term “includes” and its variants are to be read as open terms that mean “includes, but is not limited to. ” The term “based on” is to be read as “at least in part based on. ” The term “one embodiment” and “an embodiment” are to be read as “at least one embodiment. ” The term “another embodiment” is to be read as “at least one other embodiment. ” The terms “first, ” “second, ” and the like may refer to different or same objects. Other definitions, explicit and implicit, may be included below.

In some examples, values, procedures, or apparatus are referred to as “best, ” “lowest, ” “highest, ” “minimum, ” “maximum, ” or the like. It will be appreciated that such descriptions are intended to indicate that a selection among many used functional alternatives can be made, and such selections need not be better, smaller, higher, or otherwise preferable to other selections.

As described above, in NR, it is supported to indicate a downlink (DL) measurement RS (for example, Channel State Information-Reference Signal (CSI-RS)) for a terminal device to determine uplink (UL) candidate pre-coders for an aperiodic SRS (AP-SRS) via Downlink Control Information (DCI) . It is also supported to indicate a DL measurement RS (for example, CSI-RS) for a terminal device to determine UL candidate pre-coders for a periodic SRS (P-SRS) or a semi-persistent SRS (SP-SRS) via higher layer signaling. An AP-SRS can be associated with an aperiodic CSI-RS (AP-CSI-RS) . The AP-CSI-RS can be transmitted in the same slot as the DCI containing a trigger of the AP-SRS. An SRS (such as, AP-SRS, P-SRS or SP-SRS) can be associated with a periodic CSI-RS (P-CSI-RS) or a semi-persistent CSI-RS (SP-CSI-RS) .

If an AP-CSI-RS is associated with an AP-SRS and the trigger for the AP-SRS is included in an SRS request field in the DCI, the AP-CSI-RS can be transmitted in the same slot as the DCI. However, if the SRS request field indicates that no AP-SRS is triggered, how to proceed with the CSI-RS transmission has not been specified. Moreover, if a P-CSI-RS or SP-CSI-RS is associated with the AP-SRS, how to proceed with the AP-SRS transmission and the P-CSI-RS or SP-CSI-RS transmission has not been specified.

Embodiments of the present disclosure provide a solution for SRS transmission, in order to solve the problems above and one or more of other potential problems. With the solution, if the SRS request field is not included in the DCI or the SRS request field in the DCI indicates that no AP-SRS is triggered, the AP-CSI-RS associated with the AP-SRS will not be transmitted, so as to reduce communication overhead. Moreover, the solution can support P-CSI-RS or SP-CSI-RS associated with AP-SRS without any restriction.

Principle and implementations of the present disclosure will be described in detail below with reference to Figs. 1-8.

Fig. 1 shows an example communication network 100 in which implementations of the present disclosure can be implemented. The network 100 includes a network device 110 and a terminal device 120 served by the network device 110. The network 100 can provide at least one serving cell 102 to serve the terminal device 120. It is to be understood that the number of network devices, terminal devices and/or serving cells is only for the purpose of illustration without suggesting any limitations. The network 100 may include any suitable number of network devices, terminal devices and/or serving cells adapted for implementing implementations of the present disclosure.

In the communication network 100, the network device 110 can communicate data and control information to the terminal device 120 and the terminal device 120 can also communication data and control information to the network device 110. A link from the network device 110 to the terminal device 120 is referred to as a downlink (DL) , while a link from the terminal device 120 to the network device 110 is referred to as an uplink (UL) .

The communications in the network 100 may conform to any suitable standards including, but not limited to, Global System for Mobile Communications (GSM) , Long Term Evolution (LTE) , LTE-Evolution, LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , Code Division Multiple Access (CDMA) , GSM EDGE Radio Access Network (GERAN) , and the like. Furthermore, the communications may be performed according to any generation communication protocols either currently known or to be developed in the future. Examples of the communication protocols include, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the fifth generation (5G) communication protocols.

In addition to normal data communications, the network device 110 may send a RS to the terminal device 120 in a downlink. Similarly, the terminal device 120 may transmit a RS to the network device 110 in an uplink. Generally speaking, a RS is a signal sequence (also referred to as “RS sequence” ) that is known by both the network device 110 and the terminal devices 120. For example, a RS sequence may be generated and transmitted by the network device 110 based on a certain rule and the terminal device 120 may deduce the RS sequence based on the same rule. Examples of the RS may include but are not limited to downlink or uplink Demodulation Reference Signal (DMRS) , CSI-RS, Sounding Reference Signal (SRS) , Phase Tracking Reference Signal (PTRS) , Tracking Reference Signal (TRS) , fine time-frequency Tracking Reference Signal (TRS) , CSI-RS for tracking and so on.

In transmission of downlink and uplink RSs, the network device 110 may assign corresponding resources (also referred to as “RS resources” ) for the transmission and/or specify which RS sequence is to be transmitted. In some scenarios, both the network device 110 and the terminal device 120 are equipped with multiple antenna ports (or antenna elements) and can transmit specified RS sequences with the antenna ports (antenna elements) . A set of RS resources associated with a number of RS ports are also specified. A RS port may be referred to as a specific mapping of part or all of a RS sequence to one or more resource elements of a resource region allocated for RS transmission in time, frequency, and/or code domains.

For example, SRS can be used by the network device to perform uplink channel estimation, so as to perform resource allocation and configure transmission parameters for UL transmission (Physical Uplink Shared Channel (PUSCH) transmission) from the terminal device based on the result of the uplink channel estimation. SRS can also be divided into different types according to its behavior in time domain, such as P-SRS, AP-SRS and SP-SRS. As used herein, “P-SRS” refers to the SRS which is transmitted periodically in time domain. “SP-SRS” is similar to P-SRS except that the transmission of SP-SRS can be activated by a signal and deactivated by another signal. “AP-SRS” refers to the SRS whose transmission can be triggered by the network device via trigger signaling.

Two transmission schemes can be supported for UL transmission: codebook based transmission and non-codebook based transmission. The terminal device 120 can be configured with either of the two schemes with a higher layer parameter. For codebook based transmission, the terminal device 120 can determine its pre-coder for UL transmission based on the DCI received from the network device 110. For example, some filed in the DCI may indicate to the terminal device the preferred pre-coder to be used for the transmission of pre-coded SRS. For non-codebook based UL transmission, the terminal device 120 may measure some reference signal associated with the SRS to determine the pre-coder to be used for the transmission of pre-coded SRS. For the purpose of discussion without suggesting any limitations, in the following description, some embodiments will be described with reference to the non-codebook based UL transmission.

For non-codebook based UL transmission, the terminal device 120 may be configured with a SRS configuration prior to SRS transmission. The SRS configuration may indicate one or more SRS resources for the SRS transmission. Only one SRS port for each SRS resource may be configured. Only one SRS resource set can be configured for non-codebook based UL transmission. The maximum number of SRS resources included in the SRS resource set configured for non-codebook based UL transmission is 4. The terminal device 120 can measure the RS associated with the SRS to determining precoding information to be used for the transmission of the SRS. The RS associated with the SRS can be a CSI-RS, another SRS or Synchronization Signal Block (SSB) /Physical Broadcast Channel (PBCH) . For the purpose of discussion without suggesting any limitations, in the following description, some embodiments will be described with reference to CSI-RS associated with the SRS. For example, the CSI-RS associated with the SRS can be divided into different types according to its behavior in time domain, such as P-CSI-RS, AP-CSI-RS and SP-CSI-RS. As used herein, “P-CSI-RS” refers to the CSI-RS which is transmitted periodically in time domain. “SP-CSI-RS” is similar to P-CSI-RS except that the transmission of SP-CSI-RS can be activated by a signal and deactivated by another signal. “AP-CSI-RS” refers to the CSI-RS whose transmission can be triggered by the network device via trigger signaling. An AP-SRS can be associated with any of AP-CSI-RS

Fig. 2 shows a process 200 for SRS transmission according to some implementations of the present disclosure. For the purpose of discussion, the process 200 will be described with reference to Fig. 1. The process 200 may involve the network device 110 and the terminal device 120 as shown in Fig. 1. It is to be understood that the process 200 may include additional acts not shown and/or may omit some acts as shown, and the scope of the present disclosure is not limited in this regard.

In some embodiments, the network device 110 transmits (210) DCI to the terminal device 120. In some embodiments, there may be a 2-bit SRS request filed in the DCI to indicate the triggered SRS resource set. For example, table 1 shows the value of the SRS request filed for AP-SRS.

Table 1: SRS request value for AP-SRS

Value of SRS request field	Description
′00′	No aperiodic SRS trigger
′01′	The 1 ^st SRS resource set (s) configured by higher layers
′10′	The 2 ^nd SRS resource set (s) configured by higher layers
′11′	The 3 ^rd SRS resource set (s) configured by higher layers

In some embodiments, there may be a 3-bit SRS request filed in the DCI to indicate the triggered SRS resource set. For example, the first bit may be an indicator related to supplement uplink (SUL) (such as, indicating non-SUL or SUL) , and the second and third bits are used to indicate a value as shown in table 1.

In some embodiments, there may be a L-bit SRS request field in the DCI, where L is a positive integer. For example, L can be any of 2, 3 or 4. In some embodiments, there may be M states or values for the SRS request field, where M is a positive integer. For example, M can be any of 2, 3, 4, 8 or 16. In some embodiments, there may be N states or values in the M states or values for the SRS request field, to indicate one or more SRS resource sets for SRS transmission, where N is a positive integer and 1＜=N＜=M. That is, there may be (M-N) states or values to indicate “No SRS trigger” , “No aperiodic SRS trigger” or “No semi-persistent SRS activation” . For example, in some cases, N=M-1. That is, there may be 1 state or value to indicate “No SRS trigger” , “No aperiodic SRS trigger” or “No semi-persistent SRS activation” .

In some embodiments, if the state or value of SRS request field in the DCI indicates “No SRS trigger” , “No aperiodic SRS trigger” or “No semi-persistent SRS activation” , the network device 110 may not or may not be required to or may not be expected to transmit the RS associated with AP-SRS. In some embodiments, if the state or value of SRS request field in the DCI indicates “No SRS trigger” , “No aperiodic SRS trigger” or “No semi-persistent SRS activation” , the network device 110 may not or may not be required to or may not be expected to transmit the RS associated with AP-SRS in the same slot where the DCI including the SRS request field is transmitted. In some embodiments, the RS may be an AP-CSI-RS, SP-CSI-RS or P-CSI-RS.

In some embodiments, if the state or value of the SRS request field indicates “No SRS trigger” , “No aperiodic SRS trigger” or “No semi-persistent SRS activation” , the terminal device may not or may not be required to or may not be expected to receive the RS associated with AP-SRS. In some embodiments, if the state or value of the SRS request field indicates “No SRS trigger” , “No aperiodic SRS trigger” or “No semi-persistent SRS activation” , the terminal device may not or may not be required to or may not be expected to receive the RS associated with AP-SRS in the same slot where the DCI with SRS request field is received. In some embodiments, the RS may be an AP-CSI-RS, SP-CSI-RS or P-CSI-RS.

In some embodiments, if a RS which is the same as or different from that associated with the SRS transmission is configured or triggered to be transmitted by some other signaling in the same slot where the DCI including SRS request field is transmitted, this RS may be transmitted in the same slot. For example, this RS may be used for other purposes.

In some embodiments, if there is no SRS request field in the DCI, or the value of the SRS request field in the DCI indicates no aperiodic SRS trigger (for example, the value is ‘00’ ) , the network device 110 will not transmit the RS associated with the AP-SRS. For example, suppose that the RS associated with the AP-SRS is an AP-CSI-RS and the DCI is transmitted in a first slot in time domain. If there is no SRS request field in the DCI, or the value of the SRS request field in the DCI indicates no aperiodic SRS trigger (for example, the value is ‘00’ ) , the network device 110 will not or may not be required to or may not be expected to transmit the AP-CSI-RS in the first slot.

In some embodiments, there may be several DCI formats that can include the SRS request field. For example, the DCI formats which can include the SRS request field may be any of DCI format 0_1, DCI format 1_1, DCI format 2_3 and etc. In some embodiments, whether the associated AP-CSI-RS is transmitted in the same slot as the DCI or not depends on the format of the DCI. In some embodiments, for DCI format 0_1 or DCI for PUSCH scheduling, and/or DCI format 1_1 or DCI for PDSCH scheduling, the associated AP-CSI-RS may be required to, or may be expected to, or will be transmitted in the same slot as the DCI including the SRS request field. In some embodiments, for DCI format 2_3 or DCI not for PUSCH or PDSCH scheduling, the associated AP-CSI-RS may not be required to, or may not be expected to, or will not be transmitted in the same slot as the DCI including the SRS request field.

In some embodiments, if the SRS request field is present in the DCI and the value of the SRS request field indicates one or more SRS resource set (s) (for example, the value is not ‘00’ ) , then the network device 110 transmits (220) the RS associated with the SRS to the terminal device 120. For example, suppose that the RS associated with the AP-SRS is a CSI-RS and the DCI is transmitted in a first slot in time domain. In some embodiments, if the SRS request field is present in the DCI and the value of the SRS request field indicates one or more SRS resource set (s) (for example, the value is not ‘00’ ) , and the CSI-RS associated with the SRS is an AP-CSI-RS, the network device 110 may transmit the AP-CSI-RS in the same slot as the DCI, that is, in the first slot. Fig. 3A shows an example of such embodiments. In Fig. 3A, the trigger (that is, the DCI containing the SRS request filed whose value is not ‘00’ ) for the SRS and the AP-CSI-RS associated with the SRS are transmitted in the same slot. In some other embodiments, if the SRS request field is present in the DCI, and if the CSI-RS associated with the SRS is a P-CSI-RS or SP-CSI-RS, there is no need to transmit an AP-CSI-RS in the same slot (that is, the first slot) as the trigger for the SRS. In some other embodiments, if the SRS request field is present in the DCI in the first slot, and if the CSI-RS associated with the SRS is a P-CSI-RS or SP-CSI-RS, there is no need to restrict the transmission of the P-CSI-RS or SP-CSI-RS within the first slot. That is, the P-CSI-RS or SP-CSI-RS associated with the SRS can be transmitted in a second slot, which is different from the first slot. For example, the P-CSI-RS or SP-CSI-RS associated with the SRS may be configured with a periodicity or some other parameters. In some embodiments, if the periodicity or parameters for the P-CSI-RS or SP-CSI-RS indicates that the first slot is to be used for transmitting the P-CSI-RS or SP-CSI-RS, the P-CSI-RS or SP-CSI-RS will be transmitted in the same slot as the DCI including the SRS request filed. Alternatively, or in addition, if the SRS request field is present in the DCI, and if the CSI-RS associated with the SRS is a P-CSI-RS or SP-CSI-RS, there is no need to restrict the transmission of the trigger within a slot where the P-CSI-RS or SP-CSI-RS is transmitted. That is, the P-CSI-RS or SP-CSI-RS associated with the SRS can be transmitted in a second slot, which is different from the first slot. Fig. 3B shows an example of such embodiments. In Fig. 3B, the trigger (that is, the DCI containing the SRS request filed whose value is not ‘00’ ) for the SRS and the P-CSI-RS or SP-CSI-RS associated with the SRS are transmitted in different slots.

In some embodiments, in response to receiving the RS associated with the AP-SRS from the network device 110, the terminal device 120 determines (230) precoding information related to the AP-SRS based on the received RS. Then, the terminal device 120 transmits (240) , based on the precoding information, the AP-SRS to the network device 110.

In some embodiments, if the RS associated with the AP-SRS is an AP-CSI-RS, the time interval from the last symbol of the reception of the AP-CSI-RS and the first symbol of the AP-SRS transmission should be not less than a predetermined number of Orthogonal Frequency Division Multiplexing (OFDM) symbols. For example, the predetermined number is 42.

In some embodiments, if the RS associated with the AP-SRS is a P-CSI-RS or SP-CSI-RS, suppose that the time interval from the last symbol of the reception of the most recent P-CSI-RS or SP-CSI-RS prior to or no later than the first or last symbol of the transmission of AP-SRS and the first symbol of the AP-SRS transmission is represented as T. Alternatively, in some embodiments, if the RS associated with the AP-SRS is a P-CSI-RS or SP-CSI-RS, suppose that the time interval from the last symbol of the reception of the most recent P-CSI-RS or SP-CSI-RS prior to or no later than the first or last symbol of reception of the DCI with SRS request field and the first symbol of the AP-SRS transmission is also represented as T. Alternatively, in some embodiments, if the RS associated with the AP-SRS is a P-CSI-RS or SP-CSI-RS, suppose that the time interval from the last symbol of the reception of the most recent P-CSI-RS or SP-CSI-RS subsequent to or no earlier than the first or last symbol of reception of the DCI with SRS request field and the first symbol of the AP-SRS transmission is also represented as T. Alternatively, in some embodiments, if the RS associated with the AP-SRS is a P-CSI-RS or SP-CSI-RS, suppose that the time interval from the first or last symbol of the reception of the DCI with SRS request field and the first symbol of the AP-SRS transmission is also represented as T.

In some embodiments, if the time interval T is less than or equal to a predetermined threshold T _H, the terminal device 120 may not be expected to, or may not be required to, or may not transmit the triggered AP-SRS. In some embodiments, if the time interval T is less than or equal to the predetermined threshold T _H, the network device 110 may not be expected to, or may not be required to, or will not receive the triggered AP-SRS. In some embodiments, if the time interval T is equal to or greater than the predetermined threshold T _H, the terminal device 120 may be required to, or may be expected to, or will transmit the triggered AP-SRS. In some embodiments, if the time interval T is equal to or greater than the threshold T _H, the network device 110 may be expected to, or may be required to, or will receive the triggered AP-SRS.

In some embodiments, the time interval T may represent a certain number of slots, symbols or micro seconds. In some embodiments, the threshold T _H may be a predetermined number of slots, symbols or micro seconds. For example, in some embodiments, the threshold T _H may be 3 slots or 42 symbols.

In some embodiments, the threshold T _H may depend on the behavior of the associated CSI-RS in time domain. In some embodiments, the value of the threshold T _H for P-CSI-RS and/or the value of the threshold T _H for SP-CSI-RS may be different from that for AP-CSI-RS. In some embodiments, the value of the threshold T _H for P-CSI-RS or SP-CSI-RS may be less than 42 symbols.

In some embodiments, the threshold T _H may depend on the behavior of the SRS in time domain. In some embodiments, the value of the threshold T _H for P-SRS and/or the value of the threshold T _H for SP-SRS may be different from that for AP-SRS. In some embodiments, the value of the threshold T _H for P-SRS or SP-SRS may be less than 42 symbols.

In some embodiments, if the time interval between any P-CSI-RS or SP-CSI-RS transmission prior to the first symbol of the AP-SRS transmission and the first symbol of the AP-SRS transmission is equal to or greater than the threshold T _H, the terminal device 120 may be expected to, or may be required to, or will transmit the AP-SRS. In some embodiments, if the time interval between any P-CSI-RS or SP-CSI-RS prior to or no later than the first or last symbol of the reception of the DCI with AP-SRS trigger and the first symbol of the AP-SRS transmission is equal to or greater than the threshold T _H, the terminal device 120 may be expected to, or may be required to or will transmit the AP-SRS.

In some embodiments, if the RS associated with the AP-SRS is a P-CSI-RS or SP-CSI-RS, the time interval between the last symbol of the reception of the most recent P-CSI-RS or SP-CSI-RS prior to the AP-SRS transmission and the first symbol of the AP-SRS transmission can be less than the predetermined number of OFDM symbols (such as, 42 OFDM symbols) . For example, in some cases, the P-CSI-RS or SP-CSI-RS may be transmitted after the trigger for the AP-SRS. In some embodiments, in this case, the time interval between the last symbol of the most recent P-CSI-RS or SP-CSI-RS transmission prior to the AP-SRS transmission and the first symbol of the AP-SRS transmission can be less than 42 OFDM symbols. If the time interval between the last symbol of the most recent P-CSI-RS or SP-CSI-RS transmission no later than the triggering for the AP-SRS and the first symbol of the AP-SRS transmission is not less than the predetermined number of OFDM symbols (that is, 42 OFDM symbols) , the AP-SRS can be transmitted.

In some embodiments, there may be no transmission of the P-CSI-RS or SP-CSI-RS associated with the AP-SRS between the transmission of the trigger for the AP-SRS and the AP-SRS transmission, but there may be at least one transmission of P-CSI-RS or SP-CSI-RS associated with the AP-SRS prior to or no later than the transmission of the trigger for the AP-SRS. In some embodiments, in this case, the time interval between the last symbol of the transmission of the trigger for the AP-SRS and the first symbol of the AP-SRS transmission should be not less than the predetermined number of OFDM symbols (that is, 42 OFDM symbols) .

In some embodiments, after the transmission of the trigger for the AP-SRS, there may be at least one transmission of the P-CSI-RS or SP-CSI-RS associated with the AP-SRS. In some embodiments, in this case, the time interval between the first transmission of the P-CSI-RS or SP-CSI-RS associated with the AP-SRS after the transmission of the trigger for the AP-SRS and the AP-SRS transmission should be not less than the predetermined number of OFDM symbols (that is, 42 OFDM symbols) .

Fig. 4 shows an example of such embodiments. In Fig. 4, the trigger for the AP-SRS is transmitted in slot N+K, where N is a non-negative integer and K is a natural number. The P-CSI-RS or SP-CSI-RS associated with the AP-SRS is transmitted periodically in time domain, for example, with a periodicity of P slots. For example, P is also a natural number and P ＞ K. That is, the P-CSI-RS or SP-CSI-RS is transmitted in slots N, N+P, N+2P, ... and so on. As shown in Fig. 4, the AP-SRS can be transmitted in slot N+M, where M ＞ 2P and M ≤ 3P, if the time interval between the first transmission (that is, the last symbol of slot N+P) of P-CSI-RS or SP-CSI-RS after the triggering for the AP-SRS and the AP-SPS transmission (that is, the first symbol of slot N+M) is not less than the predetermined number of OFDM symbols.

In current 3GPP specifications, there are two higher layer configurations related to the SRS transmission. One of the two higher layer configurations indicates the association between the SRS and a CSI-RS, which may be represented as one or more CSI-RS resource (s) or one or more CSI-RS resource set (s) configured for AP-SRS or as a parameter “SRS-AssocCSIRS” configured for P-SRS or SP-SRS and which can also be referred to “first configuration” as used herein. The other one of the two higher layer configurations indicates a spatial relation between the SRS and a RS associated with the AP-SRS, which can be represented as a parameter “SRS-SpatialRelationInfo” and also referred to “second configuration” as used herein. However, the relationship between the two higher layer configurations has not specified clearly in the 3GPP specifications.

In some embodiments, if the first configuration is configured, the terminal device 120 may not expect to be configured with the second configuration. In this case, if the first configuration indicates that the AP-SRS is associated with an AP-CSI-RS, the AP-CSI-RS may be transmitted in the same slot as the trigger for the AP-SRS, as described above. In addition, if the first configuration indicates that the AP-SRS is associated with an P-CSI-RS or SP-CSI-RS, the P-CSI-RS or SP-CSI-RS may be transmitted based on its own configuration. That is, the P-CSI-RS or SP-CSI-RS may not need to be transmitted in the same slot as the trigger for the AP-SRS, as described above.

In some embodiments, if the second configuration is configured, no matter the first configuration is configured or not (or the terminal device 120 may not expect to be configured with the first configuration) , the SRS may be transmitted based on the RS indicated in the second configuration. For example, the second configuration may indicate that the RS associated with the SRS can be any of the following: a CSI-RS, another SRS or SSB/PBCH. In this case, even if the SRS request field is present in the DCI and/or the value of the SRS request field is not ‘00’ , there may be no need of CSI-RS transmission in the same slot as the trigger for the SRS.

In some embodiments, if the AP-SRS is associated with an AP-CSI-RS, the AP-CSI-RS associated with the AP-SRS may be implicitly triggered by the SRS request filed in the DCI. That is, the AP-SRS and the AP-CSI-RS associated with the AP-SRS can be jointly triggered. In some cases, different Quasi-Co-Location (QCL) types can be configured to the terminal device 120 to indicate different quasi co-location of RS ports. In some embodiments, if QCL type D (with respect to Spatial Rx parameter) is configured, there should be a slot offset between the transmission of the trigger for the AP-SRS and the transmission of the AP-CSI-RS associated with the AP-SRS. In addition, as described above, the time interval between the AP-CSI-RS reception and the AP-SRS transmission should be not less than a predetermined number of OFDM symbols (such as, 42 symbols) . In this event, a slot offset for the AP-CSI-RS transmission and that for the AP-SRS transmission can be determined.

In current 3GPP specifications, the slot offset for the AP-SPS resource set can be any of the following: 1, 2, ... , 8 slot (s) . Meanwhile, the slot offset for the AP-CSI-RS transmission can be any of the following: 0, 1, 2, 3, 4, 20, 24 slot (s) and so on. In some embodiments, the slot offset for the AP-SPS transmission may be greater than 3. That is, the value of the slot offset for the AP-SPS resource set cannot be 1, 2, or 3 slot (s) , since there may be no enough time between the AP-CSI-RS reception and the AP-SRS transmission for the terminal device 120. In some embodiments, the associated CSI-RS for the AP-SRS transmission may be not supported if the slot offset for the AP-CSI-RS transmission is greater than 8. In some embodiments, the slot offset for AP-CSI-RS transmission may not be 0 if QCL type D is configured. In some embodiments, the value of the slot offset for the AP-CSI-RS transmission can only be any of 1, 2 and 3 slot (s) .

In some embodiments, the slot offset for the AP-CSI-RS transmission can be indicated via the indication of the slot offset for the transmission of the trigger for the SRS. That is, the indication of the slot offset for the transmission of the trigger for the SRS can have a different description to jointly indicate both the slot offset for the transmission of the trigger for the SRS and the slot offset for the AP-CSI-RS transmission.

In some embodiments, a SRS configuration for SRS transmission may be indicated from the network device 110 to the terminal device 120 prior to the AP-SRS transmission. For example, the SRS configuration may include a field indicating a slot offset for the SRS transmission. In some embodiments, if the associated CSI-RS for AP-SRS transmission is AP-CSI-RS, and the QCL type D is configured for this CSI-RS or for any TCI state, this field originally indicating the slot offset for the AP-SRS transmission can be used to indicate a combination of the slot offset for the transmission of the trigger for the SRS and the slot offset for the AP-CSI-RS transmission. In some embodiment, if the associated CSI-RS for AP-SRS transmission is AP-CSI-RS, and the QCL type D is not configured for any TCI state, this field may only indicate the slot offset for the AP-SRS transmission.

In some embodiments, if the associated CSI-RS for AP-SRS transmission is AP-CSI-RS, the possible values of the field about the slot offset may be different in different cases. In some embodiments, if QCL type D is not configured for any TCI state, the value of the field may be selected from a set P. For example, P = {1, 2, 3, 4, 5, 6, 7, 8} . In some embodiments, if QCL type D is configured for the associated CSI-RS or for any TCI state, the value of the field may be selected from another set Q. For example, the set Q may be different from the set P. Specifically, in some cases, the set Q may be a subset of the set P. For example, Q = {4, 5, 6, 7, 8} .

In some embodiments, if the AP-SRS and the AP-CSI-RS associated with the AP-SRS are jointly triggered via the SRS request field in the DCI, the reception of the AP-CSI-RS by the terminal device 120 may be later than that of the trigger (that is, the DCI including the SRS request field) for the SRS. Specifically, in some embodiments, the time interval between the reception of the AP-CSI-RS associated with the AP-SRS and the AP-SRS transmission should be not less than the predetermined number of OFDM symbols (for example, 42 OFDM symbols) . For example, the available slot offset for the AP-CSI-RS transmission may be any of the following: 1, 2 and 3 slot (s) . Accordingly, the available slot offset for the AP-SRS transmission may be any of the following: 5, 6, 7 and 8 slot (s) . For example, if the slot offset for the AP-CSI-RS transmission is 1 slot, the slot offset for the AP-SRS transmission can be 5, 6, 7 or 8 slot (s) . If the slot offset for the AP-CSI-RS transmission is 2 slots, the slot offset for the AP-SRS transmission can be 6, 7 or 8 slot (s) . If the slot offset for the AP-CSI-RS transmission is 3 slots, the slot offset for the AP-SRS transmission can be 7 or 8 slot (s) . That is, there are total 9 possible combinations of the slot offset for the AP-CSI-RS transmission and the slot offset for the AP-SRS transmission. In some embodiments, if the slot offset for the AP-CSI-RS transmission and the slot offset for the AP-SRS transmission are jointly indicated, only 8 of the 9 possible combinations can be selected. That is, only 3 bits can be used to jointly indicate both the slot offset for the AP-CSI-RS transmission and the slot offset for the AP-SRS transmission. In some embodiments, there may be a combined indication for both the slot offset of AP-CSI-RS and the slot offset of AP-SRS. For example, the indication may be denoted as C _i, where C _i includes two values A _i and B _i and thus can be also denoted as (A _i, B _i) , where A _i is the slot offset for AP-CSI-RS, and B _i is the slot offset for AP-SRS. In some embodiments, C _i may be one of { (1, 5) , (1, 6) , (1, 7) , (1, 8) , (2, 6) , (2, 7) , (2, 8) , (3, 7) , (3, 8) } . In some embodiments, 8 of the total 9 combinations may be selected to jointly indicate both the slot offset for the AP-CSI-RS transmission and the slot offset for the AP-SRS transmission. That is, C _imay be one of { (1, 5) , (1, 6) , (1, 7) , (1, 8) , (2, 6) , (2, 7) , (2, 8) , (3, 7) } . Table 2 shows examples of the 8 selected possible combinations of the slot offset for the AP-CSI-RS transmission and the slot offset for the AP-SRS transmission.

Table 2: SRS request value for AP-SRS

Slot offset for CSI-RS	Slot offset for SRS
1 slot	5 slots
1 slot	6 slots
1 slot	7 slots
1 slot	8 slots
2 slots	6 slots
2 slots	7 slots
2 slots	8 slots
3 slots	8 slots

In some embodiments, if the AP-SRS is associated with an AP-CSI-RS, the AP-CSI-RS associated with the AP-SRS may be triggered by a CSI request filed in the DCI, while the AP-SRS may be triggered by the SRS request filed in the DCI. That is, the AP-SRS and the AP-CSI-RS associated with the AP-SRS can be separately triggered. The associated CSI-RS is based on a CSI-RS resource, rather than a RS resource set, while the AP-SRS is based on a SRS resource set. In some embodiments, in this case, the terminal device 120 may be configured with only one CSI-RS resource for the SRS resource set. In some embodiments, in this case, the time interval between the transmission of the trigger for the AP-SRS and the AP-SRS transmission should be not less than the predetermined number of OFDM symbols (that is, 42 symbols) . In some embodiments, the triggered AP-CSI-RS transmission should not be earlier than the transmission of the trigger for the AP-SRS, and the time interval between the AP-CSI-RS reception and the AP-SRS transmission may not be less than 42 symbols.

In some embodiments, if the RS associated with the AP-SRS is a P-CSI-RS, SP-CSI-RS or AP-CSI-RS, suppose that the time interval from the last symbol of the reception of the AP-CSI-RS or the most recent P-CSI-RS or SP-CSI-RS prior to or no later than the first or last symbol of the AP-SRS transmission and the first symbol of the AP-SRS transmission is represented as T. Alternatively, in some embodiments, if the RS associated with the AP-SRS is a P-CSI-RS, SP-CSI-RS or AP-CSI-RS, suppose that the time interval from the last symbol of the reception of the AP-CSI-RS or the most recent P-CSI-RS or SP-CSI-RS prior to or no later than the first or last symbol of reception of the DCI with SRS request field and the first symbol of the AP-SRS transmission is also represented as T. Alternatively, in some embodiments, if the RS associated with the AP-SRS is a P-CSI-RS, SP-CSI-RS or AP-CSI-RS, suppose that the time interval from the last symbol of the reception of the AP-CSI-RS or the most recent P-CSI-RS or SP-CSI-RS subsequent to or no earlier than the first or last symbol of reception of the DCI with SRS request field and the first symbol of the AP-SRS transmission is also represented as T. Alternatively, in some embodiments, if the RS associated with the AP-SRS is a P-CSI-RS, SP-CSI-RS or AP-CSI-RS, suppose that the time interval from the first or last symbol of the reception of the DCI with SRS request field and the first symbol of the AP-SRS transmission is also represented as T.

In some embodiments, the threshold T _H may be different in different cases. For example, suppose that the threshold T _H may equal to T _H1 in case that QCL type D is configured for the AP-CSI-RS or SP-CSI-RS, or QCL type D is configured for any one of the TCI state. Suppose that the threshold T _H may equal to T _H2 in case that QCL type D is not configured for the AP-CSI-RS or SP-CSI-RS, or QCL type D is not configured for any one of the TCI state. In some embodiments, T _H1 ≠ T _H2. For example, T _H1 ＞ T _H2. As another example, T _H1 ＜ T _H2.

In some embodiments, if the time interval between the transmission of the trigger for the AP-CSI-RS or the trigger for the AP-SRS and the AP-CSI-RS reception is less than or no greater than a predetermined threshold, no AP-SRS transmission is expected by the terminal device 120. This is because if the time interval is below the predetermined threshold, a default beam may be used by the terminal device 120 for AP-CSI-RS reception, resulting in the association between the AP-CSI-RS and the AP-SRS making no sense.

In some embodiments, the DCI indicated to the terminal device 120 may also include a SRS resource indicator (SRI) . The terminal device 120 may determine, based on the indicated SRI, some configurations related to the UL transmission. For example, the terminal device 120 may determine, based on the indicated SRI, at least one of PUSCH pre-coder, transmission rank and so on. In some embodiments, the terminal device 120 may be configured with one or more SRS resource sets, and each of the one or more SRS resource sets may include one or more SRS resources. In some embodiments, the indicated SRI may be associated with one or more SRS resources. For example, the SRI may be indicated in a certain slot and may be associated with one or more SRS resources identified by the SRI in the most recent SRS resource set that is transmitted prior to the Physical Downlink Control Channel (PDCCH) carrying the SRI. The most recent SRS resource set associated with the SRI may be the one that includes the most recent SRS resource transmitted prior to the PDCCH carrying the SRI. Fig. 5 shows an example of such embodiments. As shown in Fig. 5, the SRI is indicated in slot N+M. A SRS resource set S1 is the most recent SRS resource set that is transmitted prior to the PDCCH carrying the SRI. The SRS resource set S1 includes SRS resources transmitted in slots N, N+K1, N+K3, and N+K4, respectively. A SRS resource transmitted in slot N+K2 belongs to another SRS resource set S2. In this case, the SRI indicated in slot N+M is associated with the SRS resources transmitted in slots N, N+K1, N+K3, and N+K4, but not associated with the SRS resource transmitted in slot N+K2.

In some embodiments, for non-codebook based UL transmission, the terminal device 120 may be configured with only one SRS resource set. In some embodiments, the indicated SRI in a certain slot may be associated with the most recent transmission of one or more SRS resources identified by the SRI, as long as the one or more SRS resources belong to the configured SRS resource set for non-codebook based UL transmission, and the one or more SRS resources are transmitted prior to the PDCCH carrying the SRI.

Fig. 6 shows a flowchart of an example method 600 in accordance with some embodiments of the present disclosure. The method 600 can be implemented at the terminal device 120 as shown in Fig. 1. It is to be understood that the method 600 may include additional blocks not shown and/or may omit some blocks as shown, and the scope of the present disclosure is not limited in this regard. For the purpose of discussion, the method 600 will be described from the perspective of the terminal device 120 with reference to Fig. 1.

At block 610, the terminal device 120 receives Downlink Control Information (DCI) from the network device 110.

At block 620, in response to the DCI including a first trigger for an aperiodic SRS and the aperiodic SRS being associated with a reference signal (RS) , the terminal device 120 receives the RS from the network device 110.

At block 630, the terminal device 120 determines, based on the received RS, precoding information related to the aperiodic SRS.

At block 640, the terminal device 120 transmits, based on the precoding information, the aperiodic SRS to the network device 110.

In some embodiments, the RS is any of the following: an aperiodic Channel State Information-Reference Signal (CSI-RS) , a periodic CSI-RS, a semi-persistent CSI-RS, a Demodulation Reference Signal (DMRS) , a Phase Tracking Reference Signal (PTRS) , a Tracking Reference Signal (TRS) and an SRS.

In some embodiments, the RS associated with the aperiodic SRS is an aperiodic CSI-RS and the DCI is received in a first slot. The terminal device 120 receives the RS by receiving the aperiodic CSI-RS from the network device in the first slot.

In some embodiments, the RS associated with the aperiodic SRS is a periodic or semi-persistent CSI-RS and the DCI is received in a first slot. The terminal device 120 receives the RS by receiving the periodic or semi-persistent CSI-RS from the network device in a second slot different from the first slot.

In some embodiments, the terminal device 120 determines a time interval between the reception of the RS from the network device 110 and the transmission of the aperiodic SRS. The terminal device 120 then transmits, based on the time interval, the aperiodic SRS to the network device 110.

In some embodiments, the CSI-RS associated with the aperiodic SRS is an aperiodic CSI-RS, and the time interval is equal to or more than a predetermine number of Orthogonal Frequency Division Multiplexing symbols.

In some embodiments, the CSI-RS associated with the aperiodic SRS is a periodic or semi-persistent CSI-RS, and the time interval is less than the predetermine number of Orthogonal Frequency Division Multiplexing symbols.

In some embodiments, the RS associated with the aperiodic SRS is a CSI-RS. The terminal device 120 receives a first configuration about the association between the aperiodic SRS and the CSI-RS from the network device. The terminal device 120 determines, based on the first configuration, whether the CSI-RS associated with the aperiodic SRS is aperiodic, periodic or semi-persistent.

In some embodiments, the terminal device 120 receives the RS by receiving the CSI-RS from the network device 110 at least based on the first configuration.

In some embodiments, the terminal device 120 receives a second configuration indicating a spatial relation between the aperiodic SRS and the RS from the network device 110. The terminal device 120 determines, based on the second configuration, the RS associated with the aperiodic SRS.

In some embodiments, the CSI-RS associated with the aperiodic SRS is an aperiodic CSI-RS, and the aperiodic CSI-RS is triggered by the first trigger for the aperiodic SRS. The terminal device 120 receives the RS by determining a first slot offset for receiving the aperiodic CSI-RS and receiving the aperiodic CSI-RS based on the first slot offset.

In some embodiments, the terminal device 120 determines, at least based on the first slot offset, a second slot offset for transmitting the aperiodic SRS to the network device. The terminal device 120 transmits, based on the second slot offset, the aperiodic SRS to the network device.

Fig. 7 shows a flowchart of an example method 700 in accordance with some embodiments of the present disclosure. The method 700 can be implemented at the network device 110 as shown in Fig. 1. It is to be understood that the method 700 may include additional blocks not shown and/or may omit some blocks as shown, and the scope of the present disclosure is not limited in this regard. For the purpose of discussion, the method 700 will be described from the perspective of the network device 110 with reference to Fig. 1.

At block 710, the network device 110 transmits Downlink Control Information (DCI) to the terminal device 120.

At block 720, in response to the DCI including a first trigger for an aperiodic SRS and the aperiodic SRS being associated with a reference signal (RS) , the network device 110 transmits the RS to the terminal device 120.

At block 730, the network device 110 receives the aperiodic SRS from the terminal device. The aperiodic SRS is transmitted by the terminal device 120 at least based on the RS.

In some embodiments, the RS associated with the aperiodic SRS is an aperiodic CSI-RS and the DCI is transmitted in a first slot. The network device 110 transmits the RS by transmitting the aperiodic CSI-RS to the terminal device in the first slot.

In some embodiments, the RS associated with the aperiodic SRS is a periodic or semi-persistent CSI-RS, and the DCI is transmitted in a first slot. The network device 110 transmits the RS by transmitting the periodic or semi-persistent CSI-RS to the terminal device in a second slot, the second slot being different from the first slot.

In some embodiments, the network device 110 determines a time interval between the reception of the RS from the network device 110 to the terminal device 120 and the transmission of the aperiodic SRS from the terminal device 120 to the network device 110. The network device 110 receives, based on the time interval, the aperiodic SRS from the terminal device 120.

In some embodiments, the RS associated with the aperiodic SRS is a CSI-RS. The network device 110 transmits a first configuration about the association between the aperiodic SRS and the CSI-RS to the terminal device. The first configuration indicates whether the CSI-RS associated with the aperiodic SRS is aperiodic, periodic or semi-persistent.

In some embodiments, the network device 110 transmits the RS by transmitting the CSI-RS to the terminal device 120 at least based on the first configuration.

In some embodiments, the network device 110 transmits a second configuration indicating a spatial relation between the aperiodic SRS and the RS to the terminal device 120, such that the terminal device 120 determines the RS associated with the aperiodic SRS based on the second configuration.

In some embodiments, the CSI-RS associated with the aperiodic SRS is an aperiodic CSI-RS, and the aperiodic CSI-RS is triggered by the first trigger for the aperiodic SRS. The network device 110 transmits the RS by determining a first slot offset for transmitting the aperiodic CSI-RS and transmitting the aperiodic CSI-RS based on the first slot offset.

In some embodiments, the network device 110 determines, at least based on the first slot offset, a second slot offset for receiving the aperiodic SRS from the terminal device. The network device 110 receives, based on the second slot offset, the aperiodic SRS from the terminal device.

In some embodiments, the CSI-RS associated with the aperiodic SRS is an aperiodic CSI-RS, and the DCI further includes a second trigger for the aperiodic CSI-RS.

It can be seen that, embodiments of the present disclosure provide a solution for SRS transmission, in order to solve the problems above and one or more of other potential problems. With the solution, if the SRS request field is not included in the DCI or the SRS request field in the DCI indicates that no AP-SRS is triggered, the AP-CSI-RS associated with the AP-SRS will not be transmitted, so as to reduce communication overhead. Moreover, the solution can support P-CSI-RS or SP-CSI-RS associated with AP-SRS without any restriction.

Fig. 8 is a simplified block diagram of a device 800 that is suitable for implementing embodiments of the present disclosure. The device 800 can be considered as a further example implementation of the network device 110 as shown in Fig. 1. Accordingly, the device 800 can be implemented at or as at least a part of the network device 110.

As shown, the device 800 includes a processor 810, a memory 820 coupled to the processor 810, a suitable transmitter (TX) and receiver (RX) 840 coupled to the processor 810, and a communication interface coupled to the TX/RX 840. The memory 810 stores at least a part of a program 830. The TX/RX 840 is for bidirectional communications. The TX/RX 840 has at least one antenna to facilitate communication, though in practice an Access Node mentioned in this application may have several ones. The communication interface may represent any interface that is necessary for communication with other network elements, such as X2 interface for bidirectional communications between eNBs, S1 interface for communication between a Mobility Management Entity (MME) /Serving Gateway (S-GW) and the eNB, Un interface for communication between the eNB and a relay node (RN) , or Uu interface for communication between the eNB and a terminal device.

The program 830 is assumed to include program instructions that, when executed by the associated processor 810, enable the device 800 to operate in accordance with the embodiments of the present disclosure, as discussed herein with reference to Figs. 1 to 7. The embodiments herein may be implemented by computer software executable by the processor 810 of the device 800, or by hardware, or by a combination of software and hardware. The processor 810 may be configured to implement various embodiments of the present disclosure. Furthermore, a combination of the processor 810 and memory 820 may form processing means 850 adapted to implement various embodiments of the present disclosure.

The memory 820 may be of any type suitable to the local technical network and may be implemented using any suitable data storage technology, such as a non-transitory computer readable storage medium, semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. While only one memory 820 is shown in the device 800, there may be several physically distinct memory modules in the device 800. The processor 810 may be of any type suitable to the local technical network, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 800 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representation, it will be appreciated that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the process or method as described above with reference to Figs 6 and 7. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

The above program code may be embodied on a machine readable medium, which may be any tangible medium that may contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine readable medium may be a machine readable signal medium or a machine readable storage medium. A machine readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM) , a read-only memory (ROM) , an erasable programmable read-only memory (EPROM or Flash memory) , an optical fiber, a portable compact disc read-only memory (CD-ROM) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the present disclosure 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 example forms of implementing the claims.

Claims

A method implemented at a terminal device, comprising:

receiving Downlink Control Information (DCI) from a network device;

in response to the DCI including a first trigger for an aperiodic Sounding Reference Signal (SRS) and the aperiodic SRS being associated with a reference signal (RS) , receiving the RS from the network device;

determining, based on the received RS, precoding information related to the aperiodic SRS; and

transmitting, based on the precoding information, the aperiodic SRS to the network device.
The method of claim 1, wherein the RS is any of the following: an aperiodic Channel State Information-Reference Signal (CSI-RS) , a periodic CSI-RS, a semi-persistent CSI-RS, a Demodulation Reference Signal (DMRS) , a Phase Tracking Reference Signal (PTRS) , a Tracking Reference Signal (TRS) and an SRS.
The method of claim 1, wherein the RS associated with the aperiodic SRS is an aperiodic CSI-RS, the DCI is received in a first slot, and receiving the RS comprises:

receiving the aperiodic CSI-RS from the network device in the first slot.
The method of claim 1, wherein the RS associated with the aperiodic SRS is a periodic or semi-persistent CSI-RS, the DCI is received in a first slot, and receiving the RS comprises:

receiving the periodic or semi-persistent CSI-RS from the network device in a second slot, the second slot being different from the first slot.
The method of claim 1, wherein transmitting the aperiodic SRS comprises:

determining a time interval between the reception of the RS from the network device and the transmission of the aperiodic SRS; and

transmitting, based on the time interval, the aperiodic SRS to the network device.
The method of claim 5, wherein the CSI-RS associated with the aperiodic SRS is an aperiodic CSI-RS, and the time interval is equal to or more than a predetermine number of Orthogonal Frequency Division Multiplexing symbols.
The method of claim 5, wherein the CSI-RS associated with the aperiodic SRS is a periodic or semi-persistent CSI-RS, and the time interval is less than the predetermine number of Orthogonal Frequency Division Multiplexing symbols.
The method of claim 1, wherein the RS associated with the aperiodic SRS is a CSI-RS, and the method further comprises:

receiving a first configuration about the association between the aperiodic SRS and the CSI-RS from the network device; and

determining, based on the first configuration, whether the CSI-RS associated with the aperiodic SRS is aperiodic, periodic or semi-persistent.
The method of claim 8, wherein receiving the RS comprises:

receiving the CSI-RS from the network device at least based on the first configuration.
The method of claim 1, further comprising:

receiving a second configuration indicating a spatial relation between the aperiodic SRS and the RS from the network device; and

determining, based on the second configuration, the RS associated with the aperiodic SRS.
The method of claim 1, wherein the CSI-RS associated with the aperiodic SRS is an aperiodic CSI-RS, the aperiodic CSI-RS is triggered by the first trigger for the aperiodic SRS, and receiving the RS comprises:

determining a first slot offset for receiving the aperiodic CSI-RS; and

receiving the aperiodic CSI-RS based on the first slot offset.
The method of claim 11, wherein transmitting the aperiodic SRS comprises:

determining, at least based on the first slot offset, a second slot offset for transmitting the aperiodic SRS to the network device; and

transmitting, based on the second slot offset, the aperiodic SRS to the network device.
The method of claim 5, wherein the CSI-RS associated with the aperiodic SRS is an aperiodic CSI-RS, and the DCI further includes a second trigger for the aperiodic CSI-RS.
A method implemented at a network device, comprising:

transmitting Downlink Control Information (DCI) to a terminal device; and

in response to the DCI including a first trigger for an aperiodic Sounding Reference Signal (SRS) and the aperiodic SRS being associated with a reference signal (RS) , transmitting the RS to the terminal device; and

receiving the aperiodic SRS from the terminal device, the aperiodic SRS being transmitted by the terminal device at least based on the RS.
The method of claim 14, wherein the RS is any of the following: an aperiodic Channel State Information-Reference Signal (CSI-RS) , a periodic CSI-RS, a semi-persistent CSI-RS, a Demodulation Reference Signal (DMRS) , a Phase Tracking Reference Signal (PTRS) , a Tracking Reference Signal (TRS) and an SRS.
The method of claim 15, wherein the RS associated with the aperiodic SRS is an aperiodic CSI-RS, the DCI is transmitted in a first slot, and transmitting the RS comprises:

transmitting the aperiodic CSI-RS to the terminal device in the first slot.
The method of claim 15, wherein the RS associated with the aperiodic SRS is a periodic or semi-persistent CSI-RS, the DCI is transmitted in a first slot, and transmitting the RS comprises:

transmitting the periodic or semi-persistent CSI-RS to the terminal device in a second slot, the second slot being different from the first slot.
The method of claim 15, wherein receiving the aperiodic SRS comprises:

determining a time interval between the reception of the RS from the network device to the terminal device and the transmission of the aperiodic SRS from the terminal device to the network device; and

receiving, based on the time interval, the aperiodic SRS from the terminal device.
The method of claim 18, wherein the CSI-RS associated with the aperiodic SRS is an aperiodic CSI-RS, and the time interval is equal to or more than a predetermine number of Orthogonal Frequency Division Multiplexing symbols.
The method of claim 18, wherein the CSI-RS associated with the aperiodic SRS is a periodic or semi-persistent CSI-RS, and the time interval is less than the predetermine number of Orthogonal Frequency Division Multiplexing symbols.
The method of claim 15, wherein the RS associated with the aperiodic SRS is a CSI-RS, and the method further comprises:

transmitting a first configuration about the association between the aperiodic SRS and the CSI-RS to the terminal device, the first configuration indicating whether the CSI-RS associated with the aperiodic SRS is aperiodic, periodic or semi-persistent.
The method of claim 21, wherein transmitting the RS comprises:

transmitting the CSI-RS to the terminal device at least based on the first configuration.
The method of claim 15, further comprising:

transmitting a second configuration indicating a spatial relation between the aperiodic SRS and the RS to the terminal device, such that the terminal device determines the RS associated with the aperiodic SRS based on the second configuration.
The method of claim 15, wherein the CSI-RS associated with the aperiodic SRS is an aperiodic CSI-RS, the aperiodic CSI-RS is triggered by the first trigger for the aperiodic SRS, and transmitting the RS comprises:

determining a first slot offset for transmitting the aperiodic CSI-RS; and

transmitting the aperiodic CSI-RS based on the first slot offset.
The method of claim 24, wherein receiving the aperiodic SRS comprises:

determining, at least based on the first slot offset, a second slot offset for receiving the aperiodic SRS from the terminal device; and

receiving, based on the second slot offset, the aperiodic SRS from the terminal device.
The method of claim 18, wherein the CSI-RS associated with the aperiodic SRS is an aperiodic CSI-RS, and the DCI further includes a second trigger for the aperiodic CSI-RS.
A device comprising:

a processor; and

a memory coupled to the processor and storing instructions thereon, the instructions, when executed by the processor, causing the device to perform the method according to any of claims 1 to 13.
A device comprising:

a processor; and

a memory coupled to the processor and storing instructions thereon, the instructions, when executed by the processor, causing the device to perform the method according to any of claims 14 to 26.
A computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to carry out the method according to any of claims 1 to 13.
A computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to carry out the method according to any of claims 14 to 26.