Extended guard periods between SRS resources

Abstract

Systems and methods for extended guard periods between sounding reference signal (SRS) resources are disclosed herein. In one embodiment, a method implemented by a wireless communication device includes receiving an SRS configuration from a radio access node, the SRS configuration specifying SRS resources according to a predefined or preset minimum guard period between adjacent SRS resources in different slots. The method further includes transmitting an SRS according to the SRS configuration. In this manner, an improved SRS guard period specification is provided, leading to a better tradeoff between SRS signal quality and SRS resource utilization.

Description

[Technical field]

[0001] Related Applications This application claims the benefit of Provisional Patent Application No. 63 / 072,772, filed Aug. 31, 2020, the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to sounding reference signal (SRS) configuration in cellular communication systems. [Background technology]

[0003] SRS is used to provide channel state information (CSI) in the uplink (UL) in Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) and New Radio (NR) systems. The use for SRS is primarily to provide a reference signal for assessing channel quality, for example, to derive suitable transmit / receive beams or to perform link adaptation (i.e., setting rank, modulation coding scheme (MCS), and multiple-input multiple-output (MIMO) precoder) for Physical Downlink Shared Channel (PDSCH) and Physical Uplink Shared Channel (PUSCH) transmissions.

[0004] In LTE and NR, the SRS is configured via Radio Resource Control (RRC), and some parts of the configuration may be updated by Medium Access Control (MAC) Control Element (CE) signaling for latency reduction. The configuration includes the SRS resource allocation, as well as the time behavior (non-periodic, semi-persistent, or periodic).

[0005] SRS Settings The SRS configuration allows generating an SRS transmission pattern based on SRS resource configurations grouped into SRS resource sets, where each SRS resource is configured with an SRS resource information element (IE) in the RRC (see 3GPP 38.331 version 16.1.0).

[0006] To create SRS resources on a time-frequency grid with the current RRC configuration, each SRS resource is therefore configurable with respect to: The number of transmission combs (i.e., mapping to every nth subcarrier, where n=2 or n=4) set by the RRC parameter transmissionComb. The comb is formed in the time domain by forming several repetitions of the SRS sequence and denoting the kth repeated sequence by exp(jπkn c / n), where n c corresponds to the following comb offsets: o For each SRS resource, a comb offset is specified (i.e. which of the n combs should be used), which is configured by the RRC parameter combOffset. o The cyclic shift that maps the SRS sequence to the allocated comb is also specified, configured by the RRC parameter cyclicShift. The cyclic shift increases the number of SRS resources that can be mapped to a comb, but there is a limit on the number of cyclic shifts that can be used, which depends on the transmission comb being used. The time domain location of the SRS resource within a given slot is configured in the RRC parameter resourceMapping. The time domain start position for the SRS resource, which is constrained to be one of the last 6 symbols in a slot, is set by the RRC parameter startPosition. o The number of Orthogonal Frequency Division Multiplexing (OFDM) symbols for SRS resources (which can be set to 1, 2 or 4) is configured by the RRC parameter nrofSymbols. o The repetition factor (which can be set to 1, 2 or 4) is configured by the RRC parameter repetitionFactor. When this parameter is greater than 1, the same frequency resource is used multiple times across OFDM symbols to improve coverage as more energy is collected by the receiver. The frequency resource can also be used for beam management functions, where a gNodeB (gNB) can probe a different receive beam for each repetition. The frequency domain sounding bandwidth and position of the SRS resources in a given OFDM symbol (i.e., what part of the system bandwidth is occupied by the SRS resources) is configured with the RRC parameters freqDomainPosition, freqDomainShift, and freqHopping parameters, i.e., c-SRS, b-SRS, and b-hop. The minimum possible sounding bandwidth in a given OFDM symbol is 4 Resource Blocks (RBs).

[0007] A schematic illustration of how SRS resources are allocated in time and frequency during a given OFDM symbol in a slot (if resourceMapping-r16 is not signaled) is provided in Figure 1. Note that c-SRS controls the maximum sounding bandwidth, which may be smaller than the maximum transmission bandwidth supported by the user equipment (UE). For example, a UE may have the capability to transmit on a 40 MHz bandwidth, but c-SRS is set to a smaller value corresponding to 5 MHz, thereby concentrating the available transmit power on narrowband transmissions that improve SRS coverage.

[0008] In NR Release 16, an additional RRC parameter called resourceMapping-r16 was introduced. If resourceMapping-r16 is signaled, the UE shall ignore the RRC parameter resourceMapping. The difference between resourceMapping-r16 and resourceMapping is that the SRS resource (where the number of OFDM symbols and the repetition factor are still limited to 4) can start at any of the 14 OFDM symbols in a slot (see Figure 2), as configured by the RRC parameter startPosition-r16.

[0009] The RRC parameter resourceType sets whether the resource is transmitted as periodic, aperiodic (single transmission triggered by Downlink Control Information (DCI)), or semi-persistent (same as periodic, but the start and stop of periodic transmission is controlled by MAC CE signaling instead of RRC signaling). The RRC parameter sequenceId specifies how the SRS sequence is initialized, and the RRC parameter spatialRelationInfo sets the spatial relationship for the SRS beam with respect to a reference signal (RS), which can be either another SRS, a synchronization signal block (SSB), or a CSI reference signal (CSI-RS). Thus, if an SRS has a spatial relationship with another SRS, this SRS should be transmitted in the same beam (i.e., spatial transmit filter) as the indicated SRS.

[0010] The SRS resource is configured as part of an SRS resource set. Within the SRS resource set, the following parameters (common to all SRS resources in the SRS resource set) may be configured in RRC: Associated CSI-RS resources for each of the possible resource types (aperiodic, periodic, and semi-persistent) (this configuration is only applicable for non-codebook based UL transmission). For aperiodic SRS, the associated CSI-RS resources are set by the RRC parameter csi-RS. For periodic and semi-persistent SRS, the associated CSI-RS resources are set by the RRC parameter associatedCSI-RS. Note that all resources in a resource set must share the same resource type. For aperiodic resources, the slot offset is configured by the RRC parameter slotOffset and sets the delay from the Physical Downlink Control Channel (PDCCH) trigger reception to the start of transmission of the SRS resource measured in the slot. · Resource usage, configured by the RRC parameter usage, sets constraints and assumptions on resource properties (see 3GPP 38.214). Power control RRC parameters α, p0, pathlossReferenceRS (indicating downlink reference signals (RS) that may be used for pathloss estimation), srs-PowerControlAdjustmentStates, and (for NR Release 16) pathlossReferenceRSList-r16, used to determine the SRS transmit power.

[0011] Each SRS resource set is configured using the SRS-ResourceSet IE in the RRC (see 3GPP 38.331 version 16.1.0).

[0012] Thus, in terms of resource allocation, it can be seen that an SRS resource set configures the usage (an SRS resource set can be configured with four different usages, namely, "beamManagement", "codebook", "nonCodebook", or "antennaSwitching"), power control, non-periodic transmission timing, and downlink (DL) resource association. The SRS resource configuration controls the time and frequency allocation, the periodicity and offset of each resource, the sequence ID for each resource, and the spatial relationship information.

[0013] Guard period for antenna switching The SRS resources in the SRS resource set with use "antennaSwitching" are used to sound the channel in the UL so that the gNB can use the reciprocity to determine the preferred DL precoder. If the UE has the same number of transmit and receive chains, the UE is expected to transmit one SRS port per UE antenna. However, the mapping from SRS ports to antenna ports is up to the UE to determine and is transparent to the gNB.

[0014] For SRS usage set to "antennaSwitching", a minimum guard period between SRS resources in a slot is set to take into account the transmit antenna switching transient time. For reference, the exact text in 3GPP TS38.214 reads: "The UE is configured with a guard period of Y symbols during which the UE does not transmit any other signal, and the SRS resources of the set are transmitted in the same slot. The guard period is in the middle of the SRS resources of the set." In 3GPP TS38.214 Table 6.2.1.2-1 (see Figure 5), the minimum number of OFDM symbols to be used as the guard period between two SRS resources that belong to the same SRS resource set and are in the same slot is specified. As shown in the table, for a UE with one transmit port and two receive ports without SRS repetition and / or SRS frequency hopping, the minimum guard period is one OFDM symbol if the subcarrier spacing (SCS) is less than 120 kHz and two OFDM symbols if the SCS is 120 kHz, as shown generally in Figures 6 and 7. Here, SRS resource #1 is used to sound the first SRS port and SRS resource #2 is used to sound the second SRS port.

[0015] For adjacent transmissions of the physical uplink control channel (PUCCH) or PUSCH and SRS, a time mask is specified instead of a guard period (see section 6.3.3 of 3GPP38.101-1 V16.4.0 and section 6.3.3 of 3GPP38.101-2 V16.4.0 for time masks for frequency range 1 (FR1) and frequency range 2 (FR2), respectively). As shown in Figure 8 (from 3GPP38.101-1), the purpose of the time mask is to introduce relaxed transmission requirements for short periods between adjacent transmissions of SRS and PUCCH / PUSCH. For FR1, the time mask is valid for 10 μs before and after the SRS transmission if the same UE antenna port is used for both SRS and PUCCH / PUSCH, and for 15 μs if SRS and PUSCH / PUCCH are transmitted on different UE antenna ports. During the duration of this time mask, normal UE radio frequency (RF) requirements do not apply, which implies that the UE may transmit PUCCH / PUSCH immediately before / after the SRS transmission, but with some expected degradation of signal quality. For FR2, there is a 5 μs time mask between the PUCCH / PUSCH and the SRS before and after the PUCCH / PUSCH transmission, regardless of which antenna is being sounded. Summary of the Invention

[0016] A system and method for an extended guard period between sounding reference signal (SRS) resources is disclosed herein. In one embodiment, a method implemented by a wireless communication device includes receiving an SRS configuration from a radio access node, the SRS configuration defining SRS resources according to a predefined or preset minimum guard period between adjacent SRS resources in different slots. The method further includes transmitting an SRS according to the SRS configuration. In this manner, an improved SRS guard period specification is provided, leading to a better tradeoff between SRS signal quality and SRS resource utilization.

[0017] In one embodiment, a wireless communication device comprises one or more transmitters, one or more receivers, and a processing circuit associated with the one or more transmitters and the one or more receivers. The processing circuit is configured to cause the wireless communication device to receive an SRS configuration from a radio access node, the SRS configuration defining SRS resources according to a predefined or preset minimum guard period between adjacent SRS resources in different slots. The processing circuit is further configured to cause the wireless communication device to transmit an SRS according to the SRS configuration.

[0018] In another embodiment, a method implemented by a wireless communication device includes receiving an SRS configuration from a radio access node, the SRS configuration defining SRS resources according to a minimum guard period between adjacent SRS resources, the minimum guard period being a function of (a) whether repetition is used for SRS transmission on at least one of the adjacent SRS resources, (b) a repetition factor used for SRS transmission on at least one of the adjacent SRS resources, (c) a number of combs used for SRS transmission, (d) a subcarrier spacing, (e) a capability of the wireless communication device to support a flexible minimum guard period for SRS, or (f) a combination of two or more of (a)-(e). The method further includes transmitting the SRS in accordance with the SRS configuration.

[0019] In one embodiment, a wireless communication device comprises one or more transmitters, one or more receivers, and processing circuitry associated with the one or more transmitters and the one or more receivers. The processing circuitry is configured to cause the wireless communication device to receive an SRS configuration from a radio access node, the SRS configuration defining SRS resources according to a minimum guard period between adjacent SRS resources, the minimum guard period being a function of (a) whether repetition is used for SRS transmission on at least one of the adjacent SRS resources, (b) a repetition factor used for SRS transmission on at least one of the adjacent SRS resources, (c) a number of combs used for SRS transmission, (d) a subcarrier spacing, (e) a capability of the wireless communication device to support a flexible minimum guard period for SRS, or (f) a combination of two or more of (a)-(e). The processing circuitry is further configured to cause the wireless communication device to transmit the SRS in accordance with the SRS configuration.

[0020] Corresponding embodiments of a radio access node and a method of operation of the radio access node are also disclosed. In one embodiment, a method implemented by the radio access node includes obtaining an SRS configuration for a wireless communication device, the SRS configuration defining SRS resources according to a predefined or preset minimum guard period between adjacent SRS resources in different slots. The method further includes transmitting or initiating transmission of the SRS configuration to the wireless communication device.

[0021] In one embodiment, a radio access node comprises a processing circuit, the processing circuit configured to cause the radio access node to obtain an SRS configuration for a wireless communication device, the SRS configuration defining SRS resources according to a predefined or preset minimum guard period between adjacent SRS resources in different slots, the processing circuit further configured to cause the radio access node to transmit or initiate transmission of the SRS configuration to the wireless communication device.

[0022] In another embodiment, a method implemented by a radio access node includes obtaining an SRS configuration for a wireless communication device, the SRS configuration defining SRS resources according to a minimum guard period between adjacent SRS resources, the minimum guard period being a function of (a) whether repetition is used for SRS transmissions on at least one of the adjacent SRS resources, (b) a repetition factor used for SRS transmissions on at least one of the adjacent SRS resources, (c) a subcarrier spacing, (d) a capability of the wireless communication device to support a flexible minimum guard period for SRS, or (e) a combination of two or more of (a)-(d). The method further includes transmitting or initiating transmission of the SRS configuration to the wireless communication device.

[0023] In another embodiment, a radio access node comprises a processing circuit, the processing circuit configured to cause the radio access node to obtain an SRS configuration for a wireless communication device, the SRS configuration defining SRS resources according to a minimum guard period between adjacent SRS resources, the minimum guard period being a function of (a) whether repetition is used for SRS transmission on at least one of the adjacent SRS resources, (b) a repetition factor used for SRS transmission on at least one of the adjacent SRS resources, (c) a subcarrier spacing, (d) a capability of the wireless communication device to support a flexible minimum guard period for SRS, or (e) a combination of two or more of (a)-(d). The processing circuit is further configured to cause the radio access node to transmit or initiate transmission of the SRS configuration to the wireless communication device.

[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several aspects of the present disclosure and, together with the description, serve to explain the principles of the disclosure. [Brief description of the drawings]

[0025] [Figure 1] FIG. 13 illustrates how SRSs are allocated in time and frequency in a given OFDM symbol within a slot in 3GPP when the parameter resourceMapping-r16 is not signaled. [Diagram 2] FIG. 13 illustrates how SRSs are allocated in time and frequency in a given OFDM symbol within a slot in 3GPP when the parameter resourceMapping-r16 is signaled. [Diagram 3] FIG. 2 is a diagram illustrating an example of SRS frequency hopping. [Figure 4] FIG. 13 is a diagram illustrating an example of SRS repetition. [Diagram 5] FIG. 1 is a reproduction of Table 6.2.1.2-1 from 3GPP Technical Specification (TS) 38.214. [Figure 6] FIG. 13 illustrates a diagram showing that for a UE with one transmit port and two receive ports without SRS repetition and / or SRS frequency hopping, the minimum guard period is one OFDM symbol when the SCS is less than 120 kilohertz (kHz). [Figure 7] A diagram showing that for a UE with one transmit port and two receive ports without SRS repetition and / or SRS frequency hopping, the minimum guard period is two OFDM symbols when the SCS is 120 kHz. [Figure 8] FIG. 1 is a reproduction of Figures 6.3.3.7-1 and 6.3.3.7-2 from 3GPP TS 38.101-1. [Figure 9] FIG. 1 illustrates a problem associated with SRS configuration in existing 3GPP specifications, where SRS resources from NR Release 16 onwards may be transmitted in two adjacent OFDM symbols in two different slots. [Figure 10] FIG. 1 illustrates an example of a cellular communication system in which embodiments of the present disclosure may be implemented. [Figure 11] FIG. 16 shows that with the new capability introduced in NR Release 16 where SRS resources can be allocated in any of the 14 OFDM symbols of a slot, it is possible to configure SRS transmission in two adjacent OFDM symbols, where the two adjacent OFDM symbols belong to two different slots. [Figure 12] FIG. 2 illustrates the operation of a radio access node and a UE according to an embodiment of the present disclosure. [Figure 13] FIG. 1 illustrates an example of antenna switching with a repetition factor of 4 for a UE with one transmit port and two receive ports. [Figure 14] FIG. 13 shows an example of how a UE with one transmit port and two receive ports may be configured if the need for a guard period is removed. [Figure 15]FIG. 13 illustrates an example of an embodiment in which a new minimum guard period table with relaxed minimum guard time requirements is introduced, where the relaxed requirements for the minimum guard period depend on both the SCS and the repetition factor. [Figure 16] FIG. 17 illustrates an example of a minimum guard period table for a UE with fast antenna switching (FIG. 16) and a minimum guard period table for a UE with slow antenna switching (FIG. 17) in accordance with one embodiment, where the UE signals to the network an indication of which of the two tables is supported by the UE. [Figure 17] FIG. 17 illustrates an example of a minimum guard period table for a UE with fast antenna switching (FIG. 16) and a minimum guard period table for a UE with slow antenna switching (FIG. 17) in accordance with one embodiment, where the UE signals to the network an indication of which of the two tables is supported by the UE. [Figure 18] FIG. 2 illustrates the operation of a radio access node and a UE according to an embodiment of the present disclosure. [Figure 19] FIG. 2 is a schematic block diagram of an exemplary embodiment of a radio access node; [Figure 20] FIG. 2 is a schematic block diagram of an exemplary embodiment of a radio access node; [Figure 21] FIG. 2 is a schematic block diagram of an exemplary embodiment of a radio access node; [Figure 22] 1 is a schematic block diagram of an example embodiment of a UE. [Diagram 23] 1 is a schematic block diagram of an example embodiment of a UE. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The embodiments described below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawings, those skilled in the art will understand the concepts of the present disclosure and recognize applications of these concepts not specifically addressed herein. It is to be understood that these concepts and applications fall within the scope of the present disclosure.

[0027] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings, in which: However, other embodiments are included within the scope of the subject matter disclosed herein, and the disclosed subject matter should not be construed as being limited to only the embodiments described herein, but rather, these embodiments are provided as examples to convey the scope of the subject matter to those skilled in the art.

[0028] Generally, all terms used herein should be interpreted according to the ordinary meaning of those terms in the relevant technical field, unless a different meaning is expressly given and / or implied from the context in which the term is used. All references to a / an / the element, apparatus, component, means, step, etc. should be openly interpreted as referring to at least one instance of that element, apparatus, component, means, step, etc., unless expressly stated otherwise. The steps of any method disclosed herein need not be performed in the exact order disclosed, unless a step is expressly described as following or preceding another step, and / or it is implicit that a step must follow or precede another step. Any feature of any of the embodiments disclosed herein may be applied to any other embodiment, wherever appropriate. Similarly, any advantage of any of the embodiments may be applied to any other embodiment, and vice versa. Other objects, features, and advantages of the enclosed embodiments will become apparent from the following description.

[0029] Wireless Node: As used herein, a "wireless node" is either a wireless access node or a wireless communication device.

[0030] Radio Access Node: As used herein, a "radio access node" or "radio network node" or "radio access network node" is any node in a radio access network (RAN) of a cellular communication network that operates to transmit and / or receive signals wirelessly. Some examples of radio access nodes include, but are not limited to, a base station (e.g., a gNB in ​​a 3GPP NR network, or an enhanced or evolved Node B (eNB) in a 3GPP LTE network), a high-power or macro base station, a low-power base station (e.g., a micro base station, a pico base station, a home eNB, etc.), a relay node, a network node that implements part of the functionality of a base station (e.g., a network node that implements a gNB central unit (gNB-CU) or a network node that implements a gNB distributed unit (gNB-DU)) or a network node that implements part of the functionality of some other type of radio access node.

[0031] Communication Device: As used herein, a "communication device" is any type of device that has access to an access network. Some examples of communication devices include, but are not limited to, a mobile phone, a smartphone, a sensor device, a meter, a vehicle, a household appliance, a medical appliance, a media player, a camera, or any type of consumer electronic device, such as, but not limited to, a television, a radio, a lighting device, a tablet computer, a laptop computer, or a personal computer (PC). A communication device may be a portable, handheld, computer-equipped, or vehicle-mounted mobile device enabled to communicate voice and / or data via wireless or wired connections.

[0032] Wireless Communication Device: One type of communication device is a wireless communication device, which may be any type of wireless device having access to (i.e., served by) a wireless network (e.g., a cellular network). Some examples of wireless communication devices include, but are not limited to, UEs in 3GPP networks, machine-type communication (MTC) devices, and Internet of Things (IoT) devices. Such wireless communication devices may be or may be integrated into mobile phones, smartphones, sensor devices, meters, vehicles, household appliances, medical appliances, media players, cameras, or any type of consumer electronics, such as, but not limited to, televisions, radios, lighting devices, tablet computers, laptop computers, or PCs. Wireless communication devices may be portable, handheld, computer-equipped, or vehicle-mounted mobile devices enabled to communicate voice and / or data over a wireless connection.

[0033] Network Node: As used herein, a "network node" is any node that is part of either the RAN or the core network of a cellular communications network / system.

[0034] It should be noted that the description provided herein focuses on 3GPP cellular communication systems, and therefore 3GPP terminology or terminology similar to 3GPP terminology is often used, however, the concepts disclosed herein are not limited to 3GPP systems.

[0035] It should be noted that in the description herein, reference may be made to the term "cell." However, it is important to note that, particularly with respect to 5G NR concepts, a beam may be used in place of a cell, and thus the concepts described herein are equally applicable to both cells and beams.

[0036] Currently, there exists a problem(s). In NR Release 16, it was agreed that the SRS resource can be configured to start in any of the 14 OFDM symbols in a slot, whereas in NR Release 15, only the last 6 OFDM symbols can be used. This means that the SRS resource from NR Release 16 onwards can be transmitted in two adjacent OFDM symbols in two different slots, as shown diagrammatically in Figure 9. However, configuring two SRS resources in adjacent OFDM symbols may cause signal quality degradation of the SRS due to the transition time before / after the SRS transmission.

[0037] The minimum guard period ensures reliable signal quality of the transmitted UL signal at the expense of unused resources, in that the OFDM symbols used as guard periods cannot be used for other transmissions. In some cases, for example, when there is a small SCS, i.e., when the OFDM symbol duration is long, or when there is a high order repetition for each SRS resource, the signal quality reduction for the SRS resource due to the transient time associated with antenna switching may not be much of an issue, and thus enforcing guard periods between SRS transmissions may be associated with a higher cost than a gain.

[0038] Some aspects of the present disclosure and embodiments thereof may provide solutions to the above-mentioned or other problems. Disclosed herein are systems and methods for an extended guard time framework for SRS transmission. In some embodiments, the extended guard time framework for SRS transmission includes a guard period between slots. In some embodiments, the extended guard time framework for SRS transmission additionally or alternatively includes a flexible guard period depending on the SRS repetition factor, the number of SRS combs, the SCS, and / or the UE capabilities.

[0039] Some embodiments may provide one or more of the following technical advantage(s): Embodiments of the solutions disclosed herein may provide improved SRS guard period specification, leading to a better tradeoff between SRS signal quality and SRS resource utilization.

[0040] FIG. 10 illustrates an example of a cellular communication system 1000 in which embodiments of the present disclosure may be implemented. In the embodiments described herein, the cellular communication system 1000 is a 5G system (5GS) including a Next Generation RAN (NG-RAN) and a 5G core (5GC), or an Evolved Packet System (EPS) including an Enhanced Universal Terrestrial RAN (E-UTRAN) and an Evolved Packet Core (EPC). In this example, the RAN includes NR base stations (gNBs) in 5GS and optionally Next Generation eNBs (ng-eNBs) (e.g., LTE RAN nodes connected to 5GC), and includes base stations 1002-1 and 1002-2 including eNBs in the EPS, which control corresponding (macro) cells 1004-1 and 1004-2. The base stations 1002-1 and 1002-2 are generally referred to herein collectively as base stations 1002 and individually as base stations 1002. Similarly, the (macro) cells 1004-1 and 1004-2 are generally referred to herein collectively as the (macro) cells 1004 and individually as the (macro) cells 1004. The RAN may also include several low power nodes 1006-1 to 1006-4 that control corresponding small cells 1008-1 to 1008-4. The low power nodes 1006-1 to 1006-4 may be small base stations (such as pico or femto base stations), or remote radio heads (RRHs), etc. Although not specifically shown, one or more of the small cells 1008-1 to 1008-4 may alternatively be provided by the base station 1002. The low power nodes 1006-1 to 1006-4 are generally referred to herein collectively as the low power nodes 1006 and individually as the low power nodes 1006. Similarly, small cells 1008-1 through 1008-4 are generally referred to herein collectively as small cells 1008 and individually as small cells 1008. The cellular communication system 1000 also includes a core network 1010, referred to as 5GC in 5GS and EPC in EPS. The base stations 1002 (and optionally low power nodes 1006) are connected to the core network 1010.

[0041] Base station 1002 and low power node 1006 serve wireless communication devices 1012-1 through 1012-5 in corresponding cells 1004 and 1008. Wireless communication devices 1012-1 through 1012-5 are generally referred to herein collectively as wireless communication devices 1012 and individually as wireless communication devices 1012. In the description that follows, wireless communication devices 1012 are often UEs, although the disclosure is not limited thereto.

[0042] Next, a description of embodiments of the solutions disclosed herein is provided. Although these embodiments are described separately in some cases, it should be noted that the following embodiments can be used separately or in any desired combination.

[0043] Embodiment 1 (Guard Period Between Adjacent OFDM Symbols in Two Different Slots) In this embodiment, a guard period between adjacent SRS resources in two different slots is defined. In one embodiment, the current minimum guard period framework for SRS resource sets with use "antennaSwitching" is extended to also include a minimum guard period for transmission of SRS resources in adjacent slots. To highlight the need for this new guard period, consider the following example.

[0044] In the current NR specification, for aperiodic SRS transmission with use "antennaSwitching" and capability "1t4r", two SRS resource sets with a total of four single-port SRS resources are triggered, where at least one SRS resource in each SRS resource set is assigned. With the new capability introduced in NR Release 16, where the SRS resource can be assigned in any of the 14 OFDM symbols of a slot, as shown diagrammatically in FIG. 11, it is possible to configure SRS transmission in two adjacent OFDM symbols, where the two adjacent OFDM symbols belong to two different slots. As explained above, this may result in degradation of signal quality due to the transmit antenna switching time.

[0045] Furthermore, more UE antenna switching capabilities (e.g., "1t6r" and "1t8r") may be standardized in NR Release 17. In these cases, in some scenarios, depending on, e.g., SCS, SRS repetition factor, etc., SRS transmission will need to be scheduled on more than one slot, and thus, again, it is possible to schedule SRS transmission in two adjacent OFDM symbols across a slot boundary (see FIG. 11), which will result in signal quality degradation due to transmit antenna switching time.

[0046] In one embodiment, this problem is solved by specifying a minimum guard period between SRS resources with the use "antennaSwitching" even if the SRS resources in question belong to different slots.

[0047] In one example extension of this embodiment, a minimum guard period is also introduced for SRS extension resources that belong to one or more SRS resource sets whose usage is not necessarily set to “antennaSwitching.” For example, a minimum guard period may be specified between one SRS resource in a first slot that belongs to an SRS resource set with usage “codebook” and an SRS resource in a second slot that belongs to an SRS resource set with usage “beamManagement.”

[0048] FIG. 12 illustrates the operation of a radio access node 1200 and a UE 1012 according to at least some aspects of the embodiments described above. The radio access node 1200 may be a base station 1002 or a node implementing part of the functionality of the base station 1002 (e.g., gNB-CU). As shown, the radio access node 1200 transmits or initiates transmission of an SRS configuration to the UE 1012 (step 1202). The SRS configuration includes a predefined or preset minimum guard period between SRS resources in different (e.g., adjacent) slots. In other words, the SRS configuration defines SRS resources according to a predefined or preset minimum guard period between different (e.g., adjacent) SRS resources in different slots. In one embodiment, the predefined or preset minimum guard period between adjacent SRS resources in different slots is defined in terms of a number of OFDM symbols.

[0049] In one embodiment, the SRS configuration includes a configuration of a first SRS resource set including one or more SRS resources in a first slot and a configuration of a second SRS resource set including one or more SRS resources in a second slot that immediately follows the first slot. In one embodiment, the SRS configuration further specifies an amount of time between the first SRS resource in the first SRS resource set and a second SRS resource in the second SRS resource set that is adjacent (in time) to the first SRS resource in the first SRS resource set, the amount of time being greater than a predefined or pre-set minimum guard period between adjacent SRS resources in different slots. In one embodiment, the first SRS resource in the first SRS resource set is the last SRS resource in time from among the one or more SRS resources included in the first SRS resource set, and the second SRS resource in the second SRS resource set is the first SRS resource in time from among the one or more SRS resources included in the second SRS resource set. In one embodiment, both the first SRS resource set and the second SRS resource set are configured for antenna switching. The SRS configuration is such that the amount of time (e.g., number of OFDM symbols) between adjacent SRS resources in the first and second slots is greater than or equal to a predefined minimum guard period for SRS resources in different or adjacent slots. In other words, the SRS configuration is such that the amount of time (e.g., number of OFDM symbols) between a first SRS resource from the first SRS resource set in the first slot and a second SRS resource from the second SRS resource set in the second slot is greater than or equal to a predefined minimum guard period for adjacent SRS resources in different slots. Here, the first SRS resource is the last SRS resource (in time) among the SRS resource(s) in the first SRS resource set, and the second SRS resource is the first SRS resource (in time) among the SRS resource(s) in the second SRS resource set.

[0050] It should be noted that the predefined guard period between SRS resources (in different slots) is a flexible minimum guard period in some embodiments, as described below in the description of embodiment 2. More specifically, in one example, the predefined or preset minimum guard period between SRS resources (in different slots) is a function of whether repetition is used for SRS transmission (e.g., a repetition factor), the number of SRS combs, the SCS, and / or the capabilities of the UE, as described below.

[0051] The UE 1012 receives the SRS configuration and transmits the SRS according to the SRS configuration (step 1204).

[0052] Embodiment 2 (Relaxed Guard Period) In NR Release 15, repetition of SRS resources was included in the specification to improve the signal-to-noise ratio (SNR) of the received SRS. Currently, SRS resources can have a repetition factor of 1, 2, or 4, meaning that the same SRS resource is transmitted in one, two, or four adjacent OFDM symbols. An example of antenna switching with a repetition factor of 4 for a UE with one transmit port and two receive ports is shown in FIG. 13. As explained above, there must be a guard period between SRS resources for antenna switching to ensure reliable signal quality of the SRS resource. However, if the SRS transmission is repeated (e.g., four times), the total signal quality reduction due to the transient antenna switching time may be less noticeable compared to the case without repetition. Therefore, in this case, it may be beneficial to remove the guard period to make better use of the available time-frequency resources (i.e., find a better use for the OFDM symbol(s) that would otherwise be unused to ensure that the guard period is realized). Figure 14 shows an example of how a UE with one transmit port and two receive ports can be configured if the need for a guard period is removed. As can be seen, comparing Figures 13 and 14, in the case of Figure 14, one less OFDM symbol is used, which can then be used for other transmissions.

[0053] Thus, in one embodiment, the minimum guard time required is a function of whether repetition is used for the SRS transmission, and, as an example, is a function of the repetition factor used for the SRS transmission.

[0054] In one embodiment, the required minimum guard period additionally or alternatively depends on the SCS, as a smaller SCS results in a longer duration of the OFDM symbol duration: the longer the duration of the OFDM symbol, the smaller the effect of the transient time (assuming the transient time is the same regardless of the SCS) since the transient time will affect a smaller portion of the OFDM symbol.

[0055] In one embodiment, the required minimum guard period is a function of both the repetition factor and the SCS used for SRS transmission. As an example of this embodiment, a new minimum guard period table with relaxed minimum guard time requirements is introduced, as illustrated by Figure 15, where the relaxed requirements for the minimum guard period depend on both the SCS and the repetition factor. Note that this is only one example, and that the table could, for example, depend only on the repetition factor, or on both the repetition factor and the SCS (as shown in Figure 15).

[0056] In one embodiment, the required minimum guard period additionally or alternatively depends on the number of combs used to transmit the SRS. If two combs are used, there will be two repetitions of the SRS sequence, and if the UE switches at the beginning and end of the symbol containing the SRS transmission, each repetition of the SRS will be distorted by the switch. On the other hand, if there are, for example, three or more combs, there will be three or more repetitions of the SRS sequence in the symbol, and the repetitions that are not affected by the switch will be halfway between the first and last repetitions. The gNB may then drop the SRS that are affected by the switch and use only the SRS that are not affected by the switch in the gNB's SRS reception, thereby avoiding distortion from the switch.

[0057] Thus, in one embodiment, the minimum guard time required is a function of the number of combs used for SRS transmission. The minimum guard period is reduced when a UE transmits an SRS with three or more combs compared to the minimum guard period with two combs. In some embodiments, the minimum guard period may be 0 symbols long when three or more combs are used.

[0058] In one embodiment, there is some UE capability signaled from the UE to the gNB to inform the gNB whether the UE supports the new relaxed minimum guard period for SRS antenna switching. Thus, in one example, the required minimum guard period is a function of the UE capability. Further, in one example, the required minimum guard period is a function of the UE capability and one or more of the repetition factor used for SRS transmission, the number of combs used for SRS transmission, and the SCS.

[0059] In another example of this embodiment, several different minimum guard period tables with different guard periods are predefined or preconfigured (e.g., in the 3GPP standard). The UE signals an indication to the gNB of which (one or more) minimum guard period tables are supported by the UE from among those predefined or preconfigured tables. This indication can be signaled from the UE to the gNB, for example, during UE capability signaling. The gNB then configures the UE with one of the supported tables. Figures 16 and 17 show an example of two such minimum guard period tables, namely, a minimum guard period table for a UE with fast antenna switching (Figure 16) and a minimum guard period table for a UE with slow antenna switching (Figure 17). Which table the UE supports depends, for example, on how quickly a power amplifier (PA) in the UE is capable of ramping up the output power. The UE will signal to the gNB which of the two tables it supports. In some cases, the UE may indicate only one of the tables. However, in other cases, the UE may support both tables and thus indicate to the gNB that the UE supports both tables. The gNB then selects one of the tables to use for the UE according to an instruction from the UE. The selected table is then used to determine a minimum guard period between two SRS resources of an SRS resource set. For example, the gNB generates an SRS configuration for the UE such that at least a minimum guard period exists between adjacent SRS resources in the SRS resource set. Note that although this example focuses on the minimum guard period between SRS resources in the same SRS resource set (for antenna switching), the same applies for the minimum guard period between adjacent SRS resources in different SRS resource sets.

[0060] FIG. 18 illustrates operation of a radio access node 1800 and a UE 1012 according to at least some aspects of the embodiments described above. The radio access node 1800 may be a base station 1002 or a node implementing part of the functionality of the base station 1002 (e.g., gNB-CU). Optional steps are represented by dashed lines / boxes. As shown, optionally, the UE 1012 transmits UE capability information to the radio access node 1800 (step 1802). As described above, the UE capability information includes information indicating whether the UE 1012 supports flexible guard periods between SRS resources. For example, the UE capability information may indicate one or more guard period tables (e.g., from among two or more predefined or preconfigured tables) supported by the UE 1012.

[0061] The radio access node 1800 transmits or initiates transmission of an SRS configuration to the UE 1012 (step 1804). The SRS configuration includes a configuration of one or more SRS resource sets, each including one or more SRS resources. The SRS configuration is such that the amount of time between adjacent SRS resources (in the same slot or same SRS resource set and / or in different SRS resource sets) is greater than or equal to a minimum guard period. In this embodiment, the minimum guard period is a function of whether repetition is used for SRS transmission (e.g., the repetition factor used for SRS transmission on the associated SRS resource), the number of SRS combs, the SCS, and / or the UE capabilities (e.g., the UE capabilities of step 1802), as described above.

[0062] The UE 1012 receives the SRS configuration and transmits the SRS according to the SRS configuration (step 1806). Throughout the above description, the guard period is described as being measured in number of OFDM symbols. However, the guard period may be measured in any suitable time domain units. Additionally, while the embodiments described herein focus on the use of OFDM, the described embodiments may be used in wireless networks using other types of signal waveforms, such as, for example, SC-FDMA.

[0063] Furthermore, while the above description has focused primarily on NR (and SRS), the embodiments described herein are equally applicable to other radio access types, e.g., LTE (for which it also holds since LTE Release 16 that SRS may be transmitted in any of the 14 symbols of a slot), and other types of reference signals are not excluded. FIG. 19 is a schematic block diagram of a radio access node 1900 according to some embodiments of the present disclosure. Optional features are represented by dotted boxes. The radio access node 1900 may be, for example, a base station 1002 or 1006, or a network node implementing all or part of the functionality of the base station 1002 or gNB described herein (e.g., all or part of the functionality of the radio access node 1200 of FIG. 12 or the radio access node 1800 of FIG. 18, described above). As shown, the wireless access node 1900 includes a control system 1902 including one or more processors 1904 (e.g., a central processing unit (CPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), etc.), a memory 1906, and a network interface 1908. The one or more processors 1904 are also referred to herein as processing circuits. Additionally, the wireless access node 1900 may include one or more radio units 1910, each including one or more transmitters 1912 and one or more receivers 1914 coupled to one or more antennas 1916. The radio units 1910 may be referred to as or be part of a wireless interface circuit. In some embodiments, the radio unit(s) 1910 are external to the control system 1902 and are connected to the control system 1902, for example, via a wired connection (e.g., an optical cable). However, in some other embodiments, the wireless unit(s) 1910 and potentially the antenna(s) 1916 are integrated with the control system 1902 .The one or more processors 1904 operate to provide one or more functions of the radio access node 1900 described herein (e.g., all or a portion of the functions of the radio access node 1200 of FIG. 12 or the radio access node 1800 of FIG. 18 described above). In some embodiments, the function(s) are implemented in software, e.g., stored in the memory 1906 and executed by the one or more processors 1904.

[0064] 20 is a schematic block diagram illustrating a virtualized embodiment of a radio access node 1900 in accordance with some embodiments of the present disclosure. This description is equally applicable to other types of network nodes. Additionally, other types of network nodes may have a similar virtualized architecture. Again, optional features are represented by dotted boxes.

[0065] A "virtualized" radio access node, as used herein, is an implementation of a radio access node 1900 in which at least a portion of the functionality of the radio access node 1900 is implemented as virtual component(s) (e.g., via virtual machine(s) executing on physical processing node(s) in network(s)). As shown, in this example, the radio access node 1900 may include a control system 1902 and / or one or more radio units 1910, as described above. The control system 1902 may be connected to the radio unit(s) 1910 via, for example, an optical cable or the like. The radio access node 1900 includes one or more processing nodes 2000 coupled to or included as part of the network(s) 2002. If present, the control system 1902 or the radio unit(s) are connected to the processing node(s) 2000 via the network 2002. Each processing node 2000 includes one or more processors 2004 (e.g., a CPU, ASIC, FPGA, etc.), a memory 2006, and a network interface 2008.

[0066] In this example, the functions 2010 of the radio access node 1900 described herein (e.g., all or a portion of the functions of the radio access node 1200 of FIG. 12 or the radio access node 1800 of FIG. 18 described above) are implemented in one or more processing nodes 2000 or distributed in any desired manner across one or more processing nodes 2000 and the control system 1902 and / or the radio unit(s) 1910. In some particular embodiments, some or all of the functions 2010 of the radio access node 1900 described herein are implemented as virtual components executed by one or more virtual machines implemented in a virtual environment(s) hosted by the processing node(s) 2000. As will be appreciated by one of ordinary skill in the art, additional signaling or communication between the processing node(s) 2000 and the control system 1902 is used to perform at least some of the desired functions 2010. In particular, in some embodiments, the control system 1902 may not be included, in which case the wireless unit(s) 1910 communicate directly with the processing node(s) 2000 via an appropriate network interface(s).

[0067] In some embodiments, a computer program is provided that includes instructions that, when executed by at least one processor, cause the at least one processor to perform functions of the radio access node 1900 or a node (e.g., processing node 2000) implementing one or more of the functions 2010 of the radio access node 1900 in a virtual environment in accordance with any of the embodiments described herein. In some embodiments, a carrier is provided that comprises the computer program product described above. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as a memory).

[0068] 21 is a schematic block diagram of a radio access node 1900 according to some other embodiments of the present disclosure. The radio access node 1900 includes one or more modules 2100, each of which is implemented in software. The module(s) 2100 provide the functionality of the radio access node 1900 described herein (e.g., all or part of the functionality of the radio access node 1200 of FIG. 12 or the radio access node 1800 of FIG. 18, described above). This description is equally applicable to the processing node 2000 of FIG. 20, where the module 2100 may be implemented in one of the processing nodes 2000 or distributed across multiple processing nodes 2000 and / or distributed across the processing node(s) 2000 and the control system 1902.

[0069] 22 is a schematic block diagram of a wireless communication device 2200 according to some embodiments of the present disclosure. As shown, the wireless communication device 2200 includes one or more processors 2202 (e.g., CPU, ASIC, FPGA, etc.), a memory 2204, and one or more transceivers 2206, each including one or more transmitters 2208 and one or more receivers 2210 coupled to one or more antennas 2212. The transceiver(s) 2206 includes a radio front-end circuit connected to the antenna(s) 2212 configured to condition signals communicated between the antenna(s) 2212 and the processor(s) 2202, as will be appreciated by those skilled in the art. The processor 2202 is also referred to herein as a processing circuit. The transceiver 2206 is also referred to herein as a radio circuit. In some embodiments, the functionality of the wireless communication device 2200 described above (e.g., all or a portion of the functionality of the UE 1012 of FIG. 12 or FIG. 18 described above) may be implemented fully or partially in software, e.g., stored in memory 2204 and executed by processor(s) 2202. It should be noted that the wireless communication device 2200 may include additional components not shown in FIG. 22, such as, for example, one or more user interface components (e.g., input / output interfaces including a display, buttons, a touch screen, a microphone, a speaker(s), etc., and / or any other components for enabling input of information into and / or output of information from the wireless communication device 2200), a power supply (e.g., a battery and associated power circuitry), etc.

[0070] In some embodiments, a computer program is provided that includes instructions that, when executed by at least one processor, cause the at least one processor to perform the functions of the wireless communication device 2200 in accordance with any of the embodiments described herein. In some embodiments, a carrier is provided that comprises the computer program product described above. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer-readable storage medium (e.g., a non-transitory computer-readable medium such as a memory).

[0071] 23 is a schematic block diagram of a wireless communication device 2200 according to some other embodiments of the present disclosure. The wireless communication device 2200 includes one or more modules 2300, each of which is implemented in software. The module(s) 2300 provide the functionality of the wireless communication device 2200 described herein (e.g., all or part of the functionality of the UE 1012 of FIG. 12 or FIG. 18 described above).

[0072] Any suitable steps, methods, features, functions, or benefits disclosed herein may be implemented through one or more functional units or modules of one or more virtual devices. Each virtual device may comprise several of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessors or microcontrollers, as well as other digital hardware, which may include digital signal processors (DSPs), dedicated digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory, such as read-only memory (ROM), random access memory (RAM), cache memory, flash memory devices, optical storage devices, and the like. The program code stored in memory includes program instructions for implementing one or more communication and / or data communication protocols, as well as instructions for performing one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause each functional unit to perform a corresponding function according to one or more embodiments of the present disclosure.

[0073] Although the processes in the figures may indicate a particular order of operations performed by some embodiments of the present disclosure, it should be understood that such orders are exemplary (e.g., alternative embodiments may perform operations in a different order, combine some operations, overlap some operations, etc.).

[0074] Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure, and all such improvements and modifications are considered within the scope of the concepts disclosed herein.

Claims

1. A method implemented by a wireless communication device (1012), the method comprising: Receiving a Sounding Reference Signal (SRS) configuration (1202) from a radio access node (1200), the SRS configuration defining SRS resources according to a predefined or pre-set minimum guard period between adjacent SRS resources in different slots, the adjacent SRS resources belonging to different SRS resource sets; Transmitting an SRS according to the SRS configuration (1204); A method comprising:

2. The SRS configuration includes a first SRS resource set including one or more SRS resources in a first slot, and a second SRS resource set including one or more resources in a second slot that immediately follows the first slot; (a) a first SRS resource in the first SRS resource set; and (b) a second SRS resource in the second SRS resource set adjacent to the first SRS resource in the first SRS resource set; and and the amount of time between The method of claim 1 , wherein the amount of time is greater than the predefined or preset minimum guard period between adjacent SRS resources in different slots.

3. 3. The method of claim 2, wherein the first SRS resource in the first SRS resource set is a last SRS resource in time from among the one or more SRS resources included in the first SRS resource set, and the second SRS resource in the second SRS resource set is a first SRS resource in time from among the one or more SRS resources included in the second SRS resource set.

4. The method of claim 2 or 3, wherein both the first SRS resource set and the second SRS resource set are configured for antenna switching.

5. The method according to claim 1 , wherein the predefined or preset minimum guard period between adjacent SRS resources in different slots is defined in terms of a number of OFDM symbols.

6. The method according to claim 1 , wherein the predefined or preconfigured minimum guard period between adjacent SRS resources in different slots is a function of one or more parameters.

7. The method of claim 6 , wherein the one or more parameters include a parameter indicating whether repetition is used for SRS transmission on at least one of the adjacent SRS resources.

8. The method of claim 6 , wherein the one or more parameters include a repetition factor used for SRS transmission on at least one of the adjacent SRS resources.

9. The method of claim 6 , wherein the one or more parameters include subcarrier spacing.

10. The method of claim 6 , wherein the one or more parameters include a number of combs used for SRS transmission.

11. 11. The method of claim 6, wherein the one or more parameters include a capability of the wireless communication device (1012) to support a flexible minimum guard period for SRS.

12. 7. The method of claim 6, wherein the one or more parameters include a repetition factor and a subcarrier spacing used for SRS transmission on at least one of the adjacent SRS resources.

13. A wireless communication device (1012, 2200), One or more transmitters (2208); One or more receivers (2210); a processing circuit (2202) associated with said one or more transmitters (2208) and said one or more receivers (2210); The processing circuit (2202) is configured to: Receiving a Sounding Reference Signal (SRS) configuration (1202) from a radio access node (1200), the SRS configuration defining SRS resources according to a predefined or pre-set minimum guard period between adjacent SRS resources in different slots, the adjacent SRS resources belonging to different SRS resource sets; Transmitting an SRS according to the SRS configuration (1204); A wireless communication device (1012, 2200) configured to:

14. The wireless communication device (1012, 2200) of claim 13, wherein the processing circuit (2202) is further configured to perform a method according to any one of claims 2 to 12.

15. A method implemented by a wireless communication device (1012), the method comprising: Receiving a sounding reference signal (SRS) configuration from a radio access node, the SRS configuration defining SRS resources according to a minimum guard period between adjacent SRS resources, the adjacent SRS resources belonging to different SRS resource sets, the minimum guard period being: (a) whether repetition is used for SRS transmission on at least one of the adjacent SRS resources; (b) a repetition factor used for SRS transmission on at least one of the adjacent SRS resources; (c) the number of combs used for SRS transmission; (d) subcarrier spacing; (e) the capability of the wireless communication device (1012) to support a flexible minimum guard period for SRS; or (f) a combination of two or more of (a) through (e); and Transmitting an SRS according to the SRS configuration (1806); A method comprising:

16. The method of claim 15 , wherein the adjacent SRS resources are in the same slot.

17. The method of claim 15 , wherein the adjacent SRS resources are in different slots.

18. 18. The method of claim 15, wherein both of the adjacent SRS resources are configured for antenna switching.

19. 19. The method of claim 15, further comprising transmitting (1802) to the radio access node (1800) an indication of whether the wireless communication device (1012) supports a flexible minimum guard period for SRS, wherein the minimum guard period for the adjacent SRS resources is a function of the indication.

20. 20. The method of claim 19, wherein the indication comprises an indication of one or more of a plurality of predefined or preconfigured tables that define the minimum guard period between adjacent SRS resources as a function of one or more parameters.

21. 21. The method of claim 20, wherein the one or more parameters include either or both of the repetition factor and the subcarrier spacing used for SRS transmission on at least one of the adjacent SRS resources.

22. A wireless communication device (1012, 2200), One or more transmitters (2208); One or more receivers (2210); a processing circuit (2202) associated with said one or more transmitters (2208) and said one or more receivers (2210); The processing circuit (2202) is configured to: Receiving a sounding reference signal (SRS) configuration from a radio access node, the SRS configuration defining SRS resources according to a minimum guard period between adjacent SRS resources, the adjacent SRS resources belonging to different SRS resource sets, the minimum guard period being: (a) whether repetition is used for SRS transmission on at least one of the adjacent SRS resources; (b) a repetition factor used for SRS transmission on at least one of the adjacent SRS resources; (c) the number of combs used for SRS transmission; (d) subcarrier spacing; (e) the capability of the wireless communication device (1012) to support a flexible minimum guard period for SRS; or (f) a combination of two or more of (a) through (e); and Transmitting an SRS according to the SRS configuration (1806); A wireless communication device (1012, 2200) configured to:

23. 23. The wireless communication device (1012, 2200) of claim 22, wherein the processing circuit (2202) is further configured to perform a method according to any one of claims 16 to 21.

24. A method implemented by a radio access node (1200, 1900), the method comprising:

12. A method for providing a wireless communication device comprising: obtaining a sounding reference signal (SRS) configuration for a wireless communication device, the SRS configuration defining SRS resources according to a predefined or pre-set minimum guard period between adjacent SRS resources in different slots, the adjacent SRS resources belonging to different SRS resource sets; transmitting or initiating transmission of the SRS configuration (1202) to the wireless communication device (1012); A method comprising:

25. The SRS configuration includes a first SRS resource set including one or more SRS resources in a first slot, and a second SRS resource set including one or more resources in a second slot that immediately follows the first slot; (a) a first SRS resource in the first SRS resource set; and (b) a second SRS resource in the second SRS resource set adjacent to the first SRS resource in the first SRS resource set; and and the amount of time between 25. The method of claim 24, wherein the amount of time is greater than the predefined or preset minimum guard period between adjacent SRS resources in different slots.

26. 26. The method of claim 25, wherein the first SRS resource in the first SRS resource set is a last SRS resource in time from among the one or more SRS resources included in the first SRS resource set, and the second SRS resource in the second SRS resource set is a first SRS resource in time from among the one or more SRS resources included in the second SRS resource set.

27. 27. The method of claim 25 or 26, wherein both the first SRS resource set and the second SRS resource set are configured for antenna switching.

28. 28. The method according to any one of claims 24 to 27, wherein the predefined or preset minimum guard period between adjacent SRS resources in different slots is defined in terms of a number of OFDM symbols.

29. 29. The method according to any one of claims 24 to 28, wherein the predefined or preconfigured minimum guard period between adjacent SRS resources in different slots is a function of one or more parameters.

30. 30. The method of claim 29, wherein the one or more parameters include a parameter indicating whether repetition is used for SRS transmission on at least one of the adjacent SRS resources.

31. 30. The method of claim 29, wherein the one or more parameters include a repetition factor used for SRS transmission on at least one of the adjacent SRS resources.

32. 32. The method of any one of claims 29 to 31, wherein the one or more parameters include subcarrier spacing.

33. 33. The method of any one of claims 29 to 32, wherein the one or more parameters include a capability of the wireless communication device (1012) to support a flexible minimum guard period for SRS.

34. 30. The method of claim 29, wherein the one or more parameters include a repetition factor and a subcarrier spacing used for SRS transmission on at least one of the adjacent SRS resources.

35. A radio access node (1200, 1900), Processing circuit (1904, 2004) The processing circuit (1904, 2004) is configured to transmit to the radio access node (1200, 1900):

12. A method for providing a wireless communication device comprising: obtaining a sounding reference signal (SRS) configuration for a wireless communication device, the SRS configuration defining SRS resources according to a predefined or pre-set minimum guard period between adjacent SRS resources in different slots, the adjacent SRS resources belonging to different SRS resource sets; transmitting or initiating transmission of the SRS configuration (1202) to the wireless communication device (1012); The radio access node (1200, 1900) is configured to:

36. A radio access node (1200, 1900) according to claim 35, wherein said processing circuitry is further configured to perform a method according to any one of claims 25 to 34.

37. A method implemented by a radio access node (1800, 1900), the method comprising: Obtaining (1804) a sounding reference signal (SRS) configuration for a wireless communication device (1012), the SRS configuration defining SRS resources according to a minimum guard period between adjacent SRS resources, the adjacent SRS resources belonging to different SRS resource sets, the minimum guard period being: (a) whether repetition is used for SRS transmission on at least one of the adjacent SRS resources; (b) a repetition factor used for SRS transmission on at least one of the adjacent SRS resources; (c) subcarrier spacing; (d) the capability of the wireless communication device (1012) to support a flexible minimum guard period for SRS; or (e) a combination of two or more of (a) through (d); and transmitting or initiating transmission of the SRS configuration (1804) to the wireless communication device (1012); A method comprising:

38. 38. The method of claim 37, wherein the adjacent SRS resources are in the same slot.

39. 38. The method of claim 37, wherein the adjacent SRS resources are in different slots.

40. 40. The method of any one of claims 37 to 39, wherein both of the adjacent SRS resources are configured for antenna switching.

41. 41. The method of any one of claims 37 to 40, further comprising receiving (1802) an indication from the wireless communication device (1012) of whether the wireless communication device (1012) supports a flexible minimum guard period for SRS, and wherein the minimum guard period for the adjacent SRS resources is a function of the indication.

42. 42. The method of claim 41 , wherein the indication comprises an indication of one or more of a plurality of predefined or preconfigured tables that define the minimum guard period between adjacent SRS resources as a function of one or more parameters.

43. 43. The method of claim 42, wherein the one or more parameters include either or both of the repetition factor and the subcarrier spacing used for SRS transmission on at least one of the adjacent SRS resources.

44. A radio access node (1800, 1900), Processing circuit (1904, 2004) The processing circuit (1904, 2004) is configured to transmit to the radio access node (1800, 1900): Obtaining (1804) a sounding reference signal (SRS) configuration for a wireless communication device (1012), the SRS configuration defining SRS resources according to a minimum guard period between adjacent SRS resources, the adjacent SRS resources belonging to different SRS resource sets, the minimum guard period being: (a) whether repetition is used for SRS transmission on at least one of the adjacent SRS resources; (b) a repetition factor used for SRS transmission on at least one of the adjacent SRS resources; (c) subcarrier spacing; (d) the capability of the wireless communication device (1012) to support a flexible minimum guard period for SRS; or (e) obtaining a sounding reference signal (SRS) configuration (1804), the SRS configuration being a function of a combination of two or more of (a)-(d); transmitting or initiating transmission of the SRS configuration (1804) to the wireless communication device (1012); The radio access node (1800, 1900) is configured to:

45. A radio access node (1800, 1900) according to claim 44, wherein said processing circuitry is further configured to perform a method according to any one of claims 38 to 43.

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