Flexible multi-port SRS transmission using multiple SRS-resources

Abstract

Embodiments herein provide sounding reference signal (SRS) enhancements to support flexible mapping of multiple SRS ports to multiple SRS resources. In some embodiments, a set of SRS-resources includes a plurality of SRS-resources configured as a set, with a plurality of SRS ports distributed over more than one SRS-resource of the set. The user equipment may transmit the SRS from each SRS port included in the plurality of SRS-resources of the set.

Description

Technical Field

[0001] The present application generally relates to wireless communication systems, including mapping multiple sounding reference signal ports to multiple sounding reference signal resources or multiple symbols. Background Art

[0002] Wireless mobile communication technology uses various standards and protocols to send data between a base station and a wireless communication device. Wireless communication system standards and protocols can include, for example, the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) (e.g., 4G), 3GPP New Radio (NR) (e.g., 5G), and the IEEE 802.11 standard for wireless local area networks (WLAN) (commonly referred to within the industry as ).

[0003] As envisioned by 3GPP, different wireless communication system standards and protocols can use various radio access networks (RANs) to communicate between a base station of the RAN (which may sometimes also be referred to as a RAN node, network node, or simply a node) and a wireless communication device called a user equipment (UE). 3GPP RAN can include, for example, Global System for Mobile Communications (GSM), Enhanced Data Rate for GSM Evolution (EDGE) RAN (GERAN), Universal Terrestrial Radio Access Network (UTRAN), Evolved Universal Terrestrial Radio Access Network (E-UTRAN), and / or Next Generation Radio Access Network (NG-RAN).

[0004] Each RAN can use one or more radio access technologies (RATs) to perform communication between the base station and the UE. For example, GERAN implements GSM and / or EDGE RAT, UTRAN implements Universal Mobile Telecommunications System (UMTS) RAT or other 3GPP RAT, E-UTRAN implements LTE RAT (which is sometimes simply referred to as LTE), and NG-RAN implements NR RAT (which is sometimes referred to herein as 5G RAT, 5G NR RAT, or simply NR). In some deployments, E-UTRAN can also implement NR RAT. In some deployments, NG-RAN can also implement LTE RAT.

[0005] The base station used by the RAN can correspond to that RAN. An example of an E-UTRAN base station is an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node B (commonly also denoted as an Evolved Node B, Enhanced Node B, eNodeB, or eNB). An example of an NG-RAN base station is a Next Generation Node B (sometimes also referred to as a g Node B or gNB).

[0006] The RAN provides communication services together with external entities through its connection to the core network (CN). For example, E-UTRAN can utilize the evolved packet core (EPC), while NG-RAN can utilize the 5G core network (5GC). Description of the Drawings

[0007] To easily identify the discussion of any specific element or action, one or more of the most significant digits in the reference numerals refer to the drawing number in which the element was first introduced.

[0008] Figure 1 Illustrates SRS sequence mapping for uplink transmission according to some embodiments.

[0009] Figure 2 Illustrates a table indicating the maximum number of cyclic shifts as a function of the comb structure specified by the NR standard.

[0010] Figure 3 Illustrates an SRS - resource set for supporting multiple SRS ports distributed over more than one SRS - resource according to some embodiments.

[0011] Figure 4 Illustrates an SRS - resource set for supporting multiple SRS ports and multiple panels distributed over more than one SRS - resource according to some embodiments.

[0012] Figure 5 Illustrates an SRS - resource set with the usage set to be equal to antenna switching according to some embodiments.

[0013] Figure 6 Illustrates a method for a UE to perform SRS from SRS ports across multiple SRS - resources according to some embodiments.

[0014] Figure 7 Illustrates a method for a network node to configure SRS from SRS ports across multiple SRS - resources according to some embodiments.

[0015] Figure 8 Illustrates eight SRS ports divided into two groups of SRS ports to be transmitted on two different symbols according to some embodiments.

[0016] Figure 9 Illustrates a TD - OCC codebook created from a Hadamard matrix for mapping multiple SRS ports to multiple symbols according to some embodiments.

[0017] Figure 10 Illustrates a method for a UE to perform SRS from SRS ports across multiple symbols according to some embodiments.

[0018] Figure 11 Illustrates a method for a network node to support SRS from an SRS port across multiple symbols according to some embodiments.

[0019] Figure 12 Illustrates an example architecture of a wireless communication system according to the embodiments disclosed herein.

[0020] Figure 13 Illustrates a system for performing signaling between a wireless device and a network device according to the embodiments disclosed herein. Detailed Description

[0021] The various embodiments are described with reference to a user equipment (UE). However, the reference to the UE is provided for illustrative purposes only. The example embodiments may be used with any electronic component that can establish a connection with a network and is configured with hardware, software, and / or firmware for exchanging information and data with the network. Thus, the UE as described herein is used to represent any suitable electronic component.

[0022] Many wireless communication standards provide for the use of known signals (e.g., pilots or reference signals) for various purposes such as synchronization, measurement, equalization, control, etc. For example, in cellular wireless communication, sounding reference signals (SRS) may be used to estimate uplink channel quality. A wireless communication device or a mobile device (i.e., a UE) is capable of sending SRS to a base station (e.g., an eNB for LTE and a gNB for NR). The SRS gives information about the combined effects of multipath fading, scattering, Doppler, and power loss of the transmitted signal.

[0023] Using the SRS, the base station can estimate the channel quality and manage resources accordingly. For example, since the reference signal includes data known to both the transmitter and the receiver, the receiver can use the reference signal to determine / identify various characteristics of the communication channel. This is commonly referred to as channel estimation, which is used in many high-end wireless communications such as LTE and 5G-NR communications. The known channel attributes of a communication link in wireless communication are referred to as channel state information (CSI), and the CSI provides information indicating, for example, the combined effects of scattering, fading, and power attenuation with distance. The CSI enables adaptation of the transmission to the current channel conditions, which can be used to achieve reliable communication with high data rates in a multi-antenna system.

[0024] Generally, multi-antenna systems use precoding to improve communication. Precoding is an extension of beamforming that supports multi-stream (or multi-layer) transmission in multi-antenna wireless communication and is used to control the difference in signal attributes between the corresponding signals transmitted from multiple antennas by modifying the signals transmitted from each antenna according to a precoding matrix. In a sense, precoding can be considered as a process of cross-coupling signals (in closed-loop operation) before transmission to equalize the demodulation performance of each layer. The precoding matrix is usually selected from a codebook that defines multiple precoding matrix candidates, where the precoding matrix candidates are usually selected according to the desired performance level based on any one of multiple different factors, such as the current system configuration, the communication environment, and / or feedback information from the receiver that receives the transmitted signals.

[0025] Feedback information can be used to select a precoding matrix candidate by defining the same codebook at both the transmitter and the receiver and using the feedback information from the receiver as an indication of the preferred precoding matrix. Similarly, feedback information can be used to select the preferred ports for UE transmission.

[0026] The SRS design can include symbol position, repetition, comb, and cyclic shift. In NR version 15 (Rel-15), the design for SRS was outlined. In Rel-15, SRS can only be transmitted in the last 6 symbols of each time slot. In addition, SRS can be repeated up to four symbols, and SRS supports comb 2 / 4.

[0027] NR version 16 (Rel-16) provides enhancements to the SRS in Rel-15. In Rel-16, SRS can be transmitted in any symbol in the time slot. In addition, SRS supports repetition using 8 and 12 symbols.

[0028] NR version 17 (Rel-17) provides further enhancements to the SRS. For example, Rel-17 supports RB-level partial frequency sounding (RPFS). For RPFS, Rel-17 supports starting PRB position hopping. Rel-17 also supports SRS repetition with 10 / 14 symbols. In addition, Rel-17 supports comb 8. For comb 8, Rel-17 supports up to 6 cyclic shifts (CS).

[0029] In the current NR, SRS has four different usages, configured in the usage of SRS-resource sets. One usage of SRS is codebook-based uplink. For codebook-based uplink, the SRS resource set usage can be set to equal "codebook". The UE transmits SRS resources using multiple ports, and the network schedules the PUSCH by indicating the transmitted precoding matrix (TPMI) and rank indication (RI). The second usage of SRS is non-codebook-based uplink. For non-codebook-based uplink, the SRS resource set usage can be set to equal "non-codebook". The UE transmits multiple SRS resources, each SRS resource having a single port. The network schedules the PUSCH by indicating the SRS resource and port selection and RI (rank indication). The third usage of SRS is antenna switching. For antenna switching, the SRS resource set usage can be set to equal "antenna switching". The fourth usage of SRS is beam management. For beam management, the SRS resource set usage can be set to equal "beam management".

[0030] For multi-port SRS transmission, the current NR only supports all ports in one SRS symbol. By employing simple repetition, a single SRS-resource can support multiple symbols. In other words, a single SRS-resource can be repeated across multiple symbols. Additionally, the current NR only supports up to four ports for SRS. Each SRS port is characterized by a comb offset and a cyclic shift.

[0031] In some communication systems, it may be desirable to provide SRS enhancements to support more flexible multi-port SRS transmission. For example, it may be desirable to support eight ports. A system with flexible multi-port SRS transmission can use various embodiments described herein to support additional ports (e.g., eight ports). In some embodiments, flexible mapping can be used to map multiple SRS ports to multiple SRS resources. In some embodiments, flexible mapping can be used to map multiple SRS ports to multiple symbols.

[0032] Figure 1 An SRS sequence mapping for transmission 100 is illustrated. As shown, transmission 100 includes multiple resource elements (REs) (e.g., first RE 102, second RE 104, third RE 106, and fourth RE 108). An RE is the frequency-time unit to which the SRS sequence is mapped. Transmission 100 also includes multiple physical resource blocks (PRBs) (e.g., PRB1 110 and PRB2 112), the multiple physical resource blocks (PRBs) including multiple consecutive REs. The SRS sequence can support sequences of length 6, 12, 18, 24, and any sequence greater than or equal to 36.

[0033] To support multiple ports and UEs, a comb structure can be used for transmission 100. The SRS sequence can be mapped to frequency-domain resources (e.g., the first RE 102, the second RE 104, the third RE 106, and the fourth RE 108) using the comb structure. NR currently supports combs 2, 4, and 8 for SRS. The comb 2 structure would be a case where SRS is transmitted every other RE. Figure 1 The comb 4 structure is illustrated. As shown, in the comb 4 structure, the SRS sequence is transmitted every four resource elements. This provides four possible comb offsets 114. The comb offset indicates the starting frequency of the comb structure for the SRS sequence. Similarly, the 8-comb structure would cause SRS to be transmitted every eight resource elements. Transmission according to the comb structure allows ports from the same UE or different UEs to transmit SRS sequences without interfering with other SRS sequences. The comb N (N = 2 / 4 / 8) subsamples the REs by a factor of N, and different comb offsets are orthogonal as they do not overlap in frequency.

[0034] Another way to transmit SRS without interfering with other SRS transmissions is to apply multiple cyclic shift sequences on top of the same SRS sequence. Cyclic shift allows multiple transmissions to be applied on the same frequency REs by overlapping orthogonal sequences. Thus, a wireless communication system can use the comb structure and cyclic shift to increase its capacity. A cyclic shift sequence of length M can have M orthogonal sequences. Thus, a cyclic shift of length M can be used to create M orthogonal SRS sequences using the same SRS comb offset. The cyclic shift sequence length M can be a function of the comb size N.

[0035] Figure 2 Illustrates the maximum number of cyclic shifts Table 200 as a function of the comb structure (K TC ) specified by the NR standard. For each comb structure, there is a defined number of cyclic shifts in the NR standard. This determines how many SRS patterns can be used. For example, there can be eight cyclic shifts for the comb 2 structure, resulting in 16 (i.e., 2 * 8 = 16) ports or UEs being supported. As shown, in some embodiments, the comb 2 has up to 8 cyclic shifts, the comb 4 has up to 12 cyclic shifts, and the comb 8 has up to 6 cyclic shifts.

[0036] Embodiments of this disclosure propose using multiple resources or multiple symbols to support additional ports using flexible mapping to further enhance the SRS. Currently, some versions of NR only support four-port SRS resources. In some embodiments, an SRS resource set may include multiple SRS resources. Previously, for codebook use, different SRS resources were used to support multiple panels, where each panel was limited to supporting 4-port SRS resources. Embodiments of this disclosure describe how multiple SRS ports can be supported on more than one SRS resource.

[0037] For example, Figure 3 and Figure 4 illustrate an embodiment in which, for codebook-based uplink operation (e.g., SRS resource set usage = "codebook"), multiple SRS ports can be distributed over more than one SRS resource. Distributing multiple SRS ports over more than one SRS resource can be used to support SRS for more than four ports for a panel. A wireless communication system may support Figure 1 and Figure 2 one or both of the embodiments shown in

[0038] Figure 3 illustrates an SRS resource set 302 for supporting multiple SRS ports distributed over more than one SRS resource. For example, for an eight-port codebook-based uplink operation, a set of SRS resources configured in the SRS resource set 302 can be used to support multiple SRS ports. In the illustrated embodiment, the set of SRS resources includes two SRS resources (e.g., SRS resource 0 304 and SRS resource 1 306). Each SRS resource in the set may include four ports. To support eight ports, SRS resource 0 304 can be configured to support the first four ports, and SRS resource 1 306 can be configured to support the last four ports. Both SRS resource 0 304 and SRS resource 1 306 can be linked together to configure a pair of SRS resources configured to support eight ports.

[0039] Figure 4 illustrates an SRS resource set 402 for supporting multiple SRS ports and multiple panels distributed over more than one SRS resource. As shown, two sets of SRS resources (e.g., a first set of SRS resources 412 and a second set of SRS resources 414) can be configured in the same SRS resource set 402. A set of SRS resources may be referred to as an SRS resource group or an SRS resource pair.

[0040] Each set can be used to support multiple SRS ports distributed across SRS resources. For example, the first set 412 of SRS resources may include SRS resource 0 404 and SRS resource 1 406. SRS resource 0 404 may be configured to support the first set of ports of the first panel, and SRS resource 1 406 may be configured to support the second set of ports of the first panel. The second set 414 of SRS resources may include SRS resource 2 408 and SRS resource 3 410. SRS resource 2 408 may be configured to support the first set of ports of the second panel, and SRS resource 3 410 may be configured to support the second set of ports of the second panel.

[0041] For example, for uplink operation based on an eight-port codebook, four SRS resources may be configured in the SRS resource set 402. Each SRS resource may have 4 ports. The SRS resources configured in the SRS resource set 402 may be grouped into sets (e.g., the first set 412 of SRS resources and the second set 414 of SRS resources). Each set of SRS resources may contain two SRS resources to support the eight-port uplink operation in each set of SRS resources.

[0042] Although the illustrated embodiments only show two pairs of SRS resources (e.g., the first set 412 of SRS resources and the second set 414 of SRS resources), other embodiments may include an SRS resource set with more pairs of SRS resources to support additional panels. The specific grouping of resources may be defined by 3GPP specifications. The grouping may link SRS resources together as a way of associated ports to allow a set of SRS resources to support more ports than a single SRS resource itself can support. For example, two different four-port SRS resources may be combined to create a set of SRS resources capable of supporting eight ports. Additionally, in some embodiments, the grouping of SRS resources may include more than two SRS resources to support more than eight ports.

[0043] For codebook-based uplink operation (e.g., SRS resource set usage = "codebook"), when multiple SRS ports are distributed across a set of more than one SRS resource (as referenced Figure 3 and Figure 4 ), the network node may configure the "precoding information and number of layers" field in the downlink control information (DCI) according to a known order. For example, according to the interpretation of the "precoding information and number of layers" field in the DCI, the UE may expect the order of SRS ports mapped to the TPMI (transmission precoding matrix indicator) in a specific order. The TPMI may be used to indicate the precoder to be applied on the layer.

[0044] In some embodiments, for TPMI to SRS port mapping, the SRS ports of multiple SRS-resources in the same set (e.g., pair) can be cascaded based on the order of the SRS-resources in the SRS-resource set configuration. For example, in Figure 3 , assuming that SRS-resource 0 304 is configured before SRS-resource 1 306 in SRS-resource set 302, the order of the SRS ports to be mapped to the TPMI can be: {SRS-resource 0 port 0, SRS-resource 0 port 1, SRS-resource 0 port 2, SRS-resource 0 port 3, SRS-resource 1 port 0, SRS-resource 1 port 1, SRS-resource 1 port 2, SRS-resource 1 port 3}.

[0045] In some embodiments, for TPMI to SRS port mapping, the SRS ports of multiple SRS-resources in the same set (e.g., pair) can be sorted in an alternating pattern. Using Figure 3 as an example, the order of the SRS ports to be mapped to the TPMI can be: {SRS-resource 0 port 0, SRS-resource 1 port 0, SRS-resource 0 port 1, SRS-resource 1 port 1, SRS-resource 0 port 2, SRS-resource 1 port 2, SRS-resource 0 port 3, SRS-resource 1 port 3}.

[0046] For codebook-based uplink operation (e.g., SRS-resource set usage = "codebook"), when multiple SRS ports are distributed over a set of more than one SRS-resource and two sets are configured in the SRS-resource set as Figure 4 shown, the network node can configure the SRS resource indicator (SRI) field in the DCI to indicate the two sets.

[0047] For example, the SRS-resources can be grouped into two sets based on the order of the SRS-resources in the SRS-resource set configuration. Each set can contain an equal or nearly equal number of SRS-resources. The UE can interpret the SRI field in the DCI to indicate one of the two SRS-resource sets (e.g., pair). For example, in some embodiments, the first set is mapped to SRI = 0, and the second set is mapped to SRI = 1. In Figure 4In the example shown, assume that the SRS-resource order in the SRS-resource set configuration is {SRS-resource 0 404, SRS-resource 1 406, SRS-resource 2 408, SRS-resource 3 410}, the first set includes {SRS-resource 0 404, SRS-resource 1 406} and is mapped to SRI = 0, and the second set includes {SRS-resource 2 408, SRS-resource 3 410} and is mapped to SRI = 1. In other words, the network node can use the SRI to indicate a set or pairing of SRS resources. If the network node configures four resources, the first pair can correspond to SRI = 0 and the second pair can correspond to SRI = 1.

[0048] Even when the ports of the panel span multiple resources, the network node can use the SRI to indicate to the UE which panel should be used. In addition, the network node can use the TPMI to indicate the precoder and how it should be applied to the eight ports distributed across two SRS-resources. The UE can use this information to configure transmissions on the PUSCH.

[0049] In some embodiments, mapping ports to multiple SRS resources can be applied to antenna switching. For example, Figure 5 An SRS-resource set 502 with a usage set to equal "antenna switching" is illustrated. For antenna switching, the ports can be distributed across multiple SRS resources to support nTmR (i.e., using n Tx ports to probe m Rx ports). The UE can use multiple SRS resources (e.g., SRS-resource 0 504, SRS-resource 1 506) in the same SRS-resource set (e.g., SRS-resource set 502) to probe m Rx ports. Each SRS-resource can have k ports, where k is less than the total number of Tx ports (n Tx ports).

[0050] For example, for 8T8R antenna switching, two SRS resources (e.g., SRS-resource 0 504 and SRS-resource 1 506) can be utilized to configure the SRS resource set usage = "antenna switching". As shown, SRS-resource 0 504 can include four ports, and SRS-resource 1 506 can include four additional ports. The UE can probe the Tx ports in both SRS-resource 0 504 and SRS-resource 1 506 to use eight Tx ports to probe eight Rx ports.

[0051] Figure 6Method 600 is illustrated for a UE to perform SRS transmissions from SRS ports across multiple SRS resources. The UE may receive 602 from a network node an SRS configuration including an SRS resource set that includes a plurality of SRS resources configured as a set. The plurality of SRS ports are distributed over more than one SRS resource of the set. In some embodiments, the set may include two SRS resources, each SRS resource being mapped to four ports such that the set includes eight ports. In some embodiments, the SRS resource set may include a second set of SRS resources. The second set of SRS resources may include a plurality of SRS ports of a second panel distributed over more than one SRS resource of the second set.

[0052] The UE may transmit 604 SRS from each SRS port included in the plurality of SRS resources of the set. The UE may receive 606 from the network node feedback based on the SRS from each SRS port. In some embodiments, the feedback includes TPMI, wherein to map the TPMI to an SRS port, the SRS ports of the plurality of SRS resources in the set are cascaded based on the order of the plurality of SRS resources in the SRS configuration. In some embodiments, the plurality of SRS resources are grouped into two sets based on the order of the plurality of SRS resources in the SRS configuration, wherein each set contains an equal or nearly equal number of the plurality of SRS resources. Wherein the feedback may include an SRI field indicating the set. For example, the first set of SRS resources may be mapped to SRI = 0, and the second set of SRS resources may be mapped to SRI = 1.

[0053] The UE may configure 608 to transmit on a PUSCH from one or more ports based on the feedback. In some embodiments, the SRS configuration sets the use of the SRS resource set to antenna switching, and the plurality of SRS ports of the plurality of SRS resources are transmit ports for probing an equal number of receive ports.

[0054] Figure 7 Method 700 is illustrated for a network node to configure SRS from SRS ports across multiple SRS resources. The method 700 may be used in combination with Figure 6 the method 600 shown. The network node may transmit 702 to the UE an SRS configuration including an SRS resource set that includes a plurality of SRS resources configured as a set. The plurality of SRS ports may be distributed over more than one SRS resource of the set. The network node may receive 704 from the UE SRS from each SRS port included in the plurality of SRS resources of the set. The network node may transmit 706 to the UE feedback based on the SRS from each SRS port. The network node may schedule the UE to transmit on a PUSCH from one or more ports.

[0055] In some embodiments, to support multiple SRS ports in a single SRS resource, multiple symbols may be used. The multiple SRS ports may be split across multiple symbols. Thus, instead of repeating the previous symbol, the second symbol may have different ports from the first symbol.

[0056] For example, Figure 8 Illustrated are eight SRS ports divided into two groups of SRS ports (e.g., SRS ports 0, 1, 2, 3 and SRS ports 4, 5, 6, 7) to be sent on two different symbols. The first group of SRS ports includes SRS ports 0, 1, 2, and 3. The second group of SRS ports includes SRS ports 4, 5, 6, and 7. These two groups of ports may be split across multiple symbols such that the first group of SRS ports is sent on the first symbol 802 and the second group of SRS ports is sent on the second symbol 804. The eight SRS ports together may come from a single panel.

[0057] In some embodiments, time-domain orthogonal cover codes (TD-OCC) may be used to map multiple SRS ports to multiple symbols. In some embodiments, the TD-OCC codebook may be created from an identity matrix. For example, for a TD-OCC of length two, the two orthogonal cover codes may be {1,0} and {0,1}. Two OFDM symbols may be utilized to create multiple SRS ports. For example, to support an eight-port SRS, the UE may use the first symbol with the cover code {1,0} to send the first four ports (i.e., SRS ports 0, 1, 2, 3), and use the second symbol with the cover code {0,1} to send the next four ports (i.e., SRS ports 4, 5, 6, 7).

[0058] In some embodiments, repetition may be used for TD-OCC. For example, two, four, six, or any multiple of two additional symbols may be used to repeat Figure 8 the two symbols covering eight ports as shown. The total length of the TD-OCC may be a multiple of the number of symbols for multiple ports.

[0059] When sending the corresponding ports among the eight SRS ports, there may be a difference in the comb offset and / or cyclic shift between the two symbols being sent. The corresponding SRS ports refer to the order of the SRS ports in each group of SRS ports. For example, in the illustrated embodiment, SRS port 0 and SRS port 4 are both the first SRS ports in their respective groups and are thus referred to as corresponding. Similarly, Figure 8Other corresponding ports in [[]] include {SRS port 1 and SRS port 5}, {SRS port 2 and SRS port 6}, {SRS port 3 and SRS port 7}. In some embodiments, the corresponding SRS ports in different symbols may have different comb offsets and / or different cyclic shifts.

[0060] In some embodiments, restrictions on the comb offset and cyclic shift configurations can be implemented for the corresponding SRS ports in different symbols. In some embodiments, the restriction can be that the corresponding SRS ports in different symbols have the same comb offset. In some embodiments, the restriction can be that the corresponding SRS ports in different symbols have the same cyclic shift. In some embodiments, the restriction can be that the corresponding SRS ports in different symbols have both the same comb offset and the same cyclic shift. For example, SRS port 0 and SRS port 4 can have the same comb offset and / or cyclic shift in different symbols. Similarly, the restriction can cause other corresponding SRS ports (e.g., {SRS port 1 and 5}, {SRS port 2 and 6}, {SRS port 3 and 7}) to have the same comb offset and / or cyclic shift in different symbols.

[0061] To support multiple SRS ports in a single SRS - resource, Figure 9 illustrates how a TD - OCC codebook created from a Hadamard matrix can be used to map multiple SRS ports to multiple symbols (e.g., first symbol 902 and second symbol 904). When mapping multiple SRS ports 906 to multiple symbols, the Hadamard matrix can allow for increased capacity. The increased capacity allows for repetition such that each port can be mapped to two symbols.

[0062] For example, for a TD - OCC of length two, two orthogonal cover codes can be {1,1} and {1, - 1}. Orthogonal frequency - division multiplexing (OFDM) symbols and orthogonal cover codes can be used to configure multiple SRS ports. For example, to support eight - port SRS on two OFDM symbols (e.g., first symbol 902 and second symbol 904), four basic SRS ports (e.g., {S0,S1,S2,S3}) can be used. Each basic SRS port (e.g., {S0,S1,S2,S3}) can be mapped to a unique comb offset and cyclic shift. The eight - port SRS can be configured by applying two orthogonal TD - OCC codes on two symbols across all basic SRS ports.

[0063] For example, to support eight-port SRS, the UE may use a first symbol with a covering code {1,1} to transmit the first four ports (i.e., SRS ports 0, 1, 2, 3), and use a second symbol with a covering code {1, -1} to transmit the next four ports (i.e., SRS ports 4, 5, 6, 7). The network node may determine the SRS values of the respective SRS ports associated with the common basic SRS port (e.g., both SRS port 0 and SRS port 1 are associated with the common S0 port) by applying the covering code.

[0064] In some embodiments, to support multiple SRS ports in a single SRS-resource, a TD-OCC codebook may be created from a discrete Fourier transform (DFT) matrix (cyclic shift). The DFT matrix TD-OCC codebook may be used to support ports extended across two or more symbols. For example, the DFT matrix TD-OCC codebook may be used to support 16 ports using four symbols. In some embodiments, for a TD-OCC of length N, the i-th entry in the k-th TD-OCC code may be: Creating multiple SRS ports over multiple symbols using the DFT matrix TD-OCC codebook may be similar to using a TD-OCC codebook created from a Hadamard matrix.

[0065] In some embodiments, when creating multiple SRS ports using N OFDM symbols, frequency hopping within a frequency band may be used, where N is the number of OFDM symbols. The SRS resource configuration may include a value R, which represents the number of repeated symbols in the SRS frequency hopping within a frequency band. If the repetition factor is configured, R may be set to be equal to the value in the repetitionFactor field. Otherwise, R may be set to be equal to the number of symbols configured in the nrofSymbols field. For example, if the system uses frequency hopping within a frequency band and R is set to 2, the system may transmit 2 symbols and then hop to a different frequency to transmit additional symbols. Both repetitionFactor and nrofSymbols may be configured by the network node via radio resource control (RRC) in the SRS-resource. In some embodiments, there may be a limitation on the value of R. For example, in some embodiments, R must be divisible by the length (N) of the TD-OCC. In other words, R must be an integer multiple of N (i.e., the length of the TD-OCC).

[0066] Figure 10Method 1000 for a UE to perform SRS from SRS ports across multiple symbols is illustrated. The UE may receive 1002 from a network node an SRS configuration that maps multiple SRS ports across multiple symbols using a TD-OCC codebook. The UE may transmit 1004 SRS from each SRS port using multiple symbols. The UE may receive 1006 feedback from the network node based on the SRS from each SRS port. The UE may configure 1008 to transmit from one or more ports on a PUSCH based on the feedback.

[0067] In some embodiments, the TD-OCC codebook is created from an identity matrix. In some embodiments, corresponding SRS ports in different symbols have the same comb offset. In some embodiments, corresponding SRS ports in different symbols have the same cyclic shift. In some embodiments, the TD-OCC codebook is created from a Hadamard matrix. In some embodiments, the TD-OCC codebook is created from a DFT matrix. In some embodiments, the UE may perform frequency hopping while transmitting the SRS. In some embodiments, the number of repeated symbols in an in-SRS frequency hop must be divisible by the length of the TD-OCC.

[0068] Figure 11 Method 1100 for a network node to support SRS from SRS ports across multiple symbols is illustrated. The method 1100 may be used in combination with Figure 10 the method 1000 shown. The network node may convey 1102 to the UE an SRS configuration that maps multiple SRS ports across multiple symbols using a TD-OCC codebook. The network node receives 1104 SRS transmitted on multiple symbols from the SRS ports of the UE. The network node may convey 1106 feedback from the network node based on the SRS from each SRS port.

[0069] Figure 12 An example architecture of a wireless communication system 1200 according to embodiments disclosed herein is illustrated. The following description provided is for an example wireless communication system 1200 operating in conjunction with the LTE system standard and / or 5G or NR system standards provided in 3GPP technical specifications.

[0070] As Figure 12 shown, the wireless communication system 1200 includes UEs 1202 and 1204 (although any number of UEs may be used). In this example, UEs 1202 and 1204 are illustrated as smartphones (e.g., handheld touchscreen mobile computing devices capable of connecting to one or more cellular networks), but may also include any mobile or non-mobile computing device configured for wireless communication.

[0071] UE 1202 and UE 1204 may be configured to be communicatively coupled with RAN 1206. In an embodiment, RAN 1206 may be an NG-RAN, E-UTRAN, etc. UE 1202 and UE 1204 utilize connections (or channels) with RAN 1206 (shown as connection 1208 and connection 1210 respectively), where each connection (or channel) includes a physical communication interface. RAN 1206 may include one or more base stations that implement connection 1208 and connection 1210, such as base station 1212 and base station 1214.

[0072] In this example, connection 1208 and connection 1210 are air interfaces that implement such communicative coupling and may conform to the RAT used by RAN 1206, such as LTE and / or NR.

[0073] In some embodiments, UE 1202 and UE 1204 may also directly exchange communication data via sidelink interface 1216. UE 1204 is shown configured to access an access point (shown as AP 1218) via connection 1220. By way of example, connection 1220 may include a local wireless connection, such as a connection conforming to any IEEE 802.11 protocol, where AP 1218 may include a router. In this example, AP 1218 may not be connected to another network (e.g., the Internet) via CN 1224.

[0074] In an embodiment, UE 1202 and UE 1204 may be configured to communicate with each other or with base station 1212 and / or base station 1214 over a multi-carrier communication channel using OFDM communication signals according to various communication techniques, such as but not limited to, orthogonal frequency division multiple access (OFDMA) communication techniques (e.g., for downlink communication) or single carrier frequency division multiple access (SC-FDMA) communication techniques (e.g., for uplink and ProSe or sidelink communication), but the scope of the embodiment is not limited in this regard. The OFDM signal may include a plurality of orthogonal sub-carriers.

[0075] In some embodiments, all or part of base station 1212 or base station 1214 may be implemented as one or more software entities operating on a server computer as part of a virtual network. Additionally, or in other embodiments, base station 1212 or base station 1214 may be configured to communicate with each other via interface 1222. In an embodiment where wireless communication system 1200 is an LTE system (e.g., when CN 1224 is an EPC), interface 1222 may be an X2 interface. The X2 interface may be defined between two or more base stations (e.g., two or more eNBs, etc.) connected to the EPC and / or between two eNBs connected to the EPC. In an embodiment where wireless communication system 1200 is an NR system (e.g., when CN 1224 is a 5GC), interface 1222 may be an Xn interface. The Xn interface is defined between two or more base stations (e.g., two or more gNBs, etc.) connected to the 5GC, between base station 1212 (e.g., gNB) and an eNB connected to the 5GC, and / or between two eNBs connected to the 5GC (e.g., CN 1224).

[0076] RAN 1206 is shown communicatively coupled to CN 1224. CN 1224 may include one or more network elements 1226 configured to provide various data and telecommunications services to customers / subscribers (e.g., users of UE 1202 and UE 1204) connected to CN 1224 via RAN 1206. The components of CN 1224 may be implemented in one physical device or separate physical devices including components for reading and executing instructions from a machine-readable or computer-readable medium (e.g., a non-transitory machine-readable storage medium).

[0077] In an embodiment, CN 1224 may be an EPC, and RAN 1206 may be connected to CN 1224 via S1 interface 1228. In an embodiment, S1 interface 1228 may be divided into two parts: an S1 user plane (S1-U) interface that carries traffic data between base station 1212 or base station 1214 and a serving gateway (S-GW), and an S1-MME interface that is a signaling interface between base station 1212 or base station 1214 and a mobility management entity (MME).

[0078] In an embodiment, CN 1224 can be 5GC, and RAN 1206 can be connected to CN 1224 via NG interface 1228. In an embodiment, NG interface 1228 can be divided into two parts: the NG user plane (NG-U) interface, which carries traffic data between base station 1212 or base station 1214 and the user plane function (UPF), and the S1 control plane (NG-C) interface, which is a signaling interface between base station 1212 or base station 1214 and the access and mobility management function (AMF).

[0079] Generally, application server 1230 can be an element that provides an application using Internet Protocol (IP) bearer resources for use with CN 1224 (e.g., packet-switched data services). Application server 1230 can also be configured to support one or more communication services (e.g., VoIP sessions, group communication sessions, etc.) for UEs 1202 and 1204 via CN 1224. Application server 1230 can communicate with CN 1224 through IP communication interface 1232.

[0080] Figure 13 System 1300 for performing signaling 1334 between wireless device 1302 and network device 1318 according to embodiments disclosed herein is illustrated. System 1300 can be part of a wireless communication system as described herein. Wireless device 1302 can be, for example, a UE of a wireless communication system. Network device 1318 can be, for example, a base station of a wireless communication system (e.g., eNB or gNB).

[0081] Wireless device 1302 can include one or more processors 1304. Processor 1304 can execute instructions to perform various operations of wireless device 1302 as described herein. Processor 1304 can include one or more baseband processors implemented using, for example, a central processing unit (CPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a controller, a field programmable gate array (FPGA) device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein.

[0082] Wireless device 1302 can include a memory 1306. Memory 1306 can be a non-transitory computer-readable storage medium storing instructions 1308 (which can include, for example, instructions executed by processor 1304). Instructions 1308 can also be referred to as program code or a computer program. Memory 1306 can also store data used by processor 1304 and results calculated by the processor.

[0083] Wireless device 1302 may include one or more transceivers 1310, and the one or more transceivers may include radio frequency (RF) transmitter and / or receiver circuitry that uses the antenna 1312 of wireless device 1302 to facilitate transmitted or received signaling (e.g., signaling 1334) between wireless device 1302 and other devices (e.g., network device 1318) according to a corresponding RAT.

[0084] Wireless device 1302 may include one or more antennas 1312 (e.g., one, two, four, or more). For embodiments with multiple antennas 1312, wireless device 1302 may take advantage of the spatial diversity of these multiple antennas 1312 to transmit and / or receive multiple different data streams on the same time-frequency resources. This behavior may be referred to as, for example, multiple-input multiple-output (MIMO) behavior (referring to the multiple antennas used at each of the transmitting and receiving devices to achieve this aspect). MIMO transmission performed by wireless device 1302 may be implemented according to precoding (or digital beamforming) applied to wireless device 1302, where the wireless device multiplexes data streams between antennas 1312 based on known or assumed channel characteristics such that each data stream is received with an appropriate signal strength relative to the other streams and at a desired location in the spatial domain (e.g., the location of the receiver associated with that data stream). Certain embodiments may use single-user MIMO (SU-MIMO) methods (where the data streams are all directed to a single receiver) and / or multi-user MIMO (MU-MIMO) methods (where individual data streams may be directed to separate (different) receivers at different locations in the spatial domain).

[0085] In certain embodiments with multiple antennas, wireless device 1302 may implement analog beamforming techniques, whereby the phases of the signals transmitted by antennas 1312 are relatively adjusted such that the (combined) transmission of antennas 1312 has directivity (which is sometimes referred to as beam steering).

[0086] Wireless device 1302 may include one or more interfaces 1314. Interface 1314 may be used to provide input to wireless device 1302 or output from the wireless device. For example, wireless device 1302 as a UE may include interfaces 1314 such as a microphone, speaker, touch screen, buttons, etc. to allow a user of the UE to provide input to and / or output from the UE. Other interfaces of such a UE may consist of transmitters, receivers, and other circuitry (e.g., other than the transceivers 1310 / antennas 1312 already described) that allow communication between the UE and other devices and may operate according to known protocols (e.g., etc.).

[0087] Wireless device 1302 may include an SRS module 1316. The SRS module 1316 may be implemented via hardware, software, or a combination thereof. For example, the SRS module 1316 may be implemented as a processor, circuitry, and / or instructions 1308 stored in a memory 1306 and executed by a processor 1304. In some examples, the SRS module 1316 may be integrated within the processor 1304 and / or transceiver 1310. For example, the SRS module 1316 may be implemented by a combination of software components (e.g., executed by a DSP or a general-purpose processor) and hardware components (e.g., logic gates and circuitry) within the processor 1304 or transceiver 1310.

[0088] The SRS module 1316 may be used in various aspects of the present disclosure, for example, Figures 1 to 10 aspects. The SRS module 1316 is configured to transmit SRS based on a configuration from a network device 1318.

[0089] The network device 1318 may include one or more processors 1320. The processor 1320 may execute instructions to perform various operations of the network device 1318 as described herein. The processor 1320 may include one or more baseband processors implemented using, for example, a CPU, a DSP, an ASIC, a controller, an FPGA device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein.

[0090] The network device 1318 may include a memory 1322. The memory 1322 may be a non-transitory computer-readable storage medium storing instructions 1324 (which may include, for example, instructions executed by the processor 1320). The instructions 1324 may also be referred to as program code or a computer program. The memory 1322 may also store data used by the processor 1320 and results calculated by the processor.

[0091] The network device 1318 may include one or more transceivers 1326, which may include RF transmitter and / or receiver circuitry that uses an antenna 1328 of the network device 1318 to facilitate signaling (e.g., signaling 1334) to and / or from the network device 1318 with other devices (e.g., wireless device 1302) according to a corresponding RAT.

[0092] The network device 1318 may include one or more antennas 1328 (e.g., one, two, four, or more). In an embodiment having multiple antennas 1328, the network device 1318 may perform MIMO, digital beamforming, analog beamforming, beam control, etc. as described above.

[0093] The network device 1318 may include one or more interfaces 1330. The interfaces 1330 may be used to provide input to or output from the network device 1318. For example, the network device 1318, being a base station, may include an interface 1330 composed of a transmitter, a receiver, and other circuits (e.g., in addition to the transceiver 1326 / antenna 1328 already described), which enables the base station to communicate with other equipment in the core network and / or enables the base station to communicate with an external network, a computer, a database, etc., for the purpose of operating, managing, and maintaining the base station or other equipment operably connected to the base station.

[0094] The network device 1318 may include an SRS configuration module 1332. The SRS configuration module 1332 may be implemented via hardware, software, or a combination thereof. For example, the SRS configuration module 1332 may be implemented as a processor, a circuit, and / or instructions 1324 stored in the memory 1322 and executed by the processor 1320. In some examples, the SRS configuration module 1332 may be integrated within the processor 1320 and / or the transceiver 1326. For example, the SRS configuration module 1332 may be implemented by a combination of software components (e.g., executed by a DSP or a general-purpose processor) and hardware components (e.g., logic gates and circuits) within the processor 1320 or the transceiver 1326.

[0095] The SRS configuration module 1332 may be used in various aspects of the present disclosure, for example, Figures 1 to 10 aspects of. The SRS configuration module 1332 is configured to configure SRS transmissions from the wireless device 1302.

[0096] Embodiments contemplated herein include an apparatus that includes components for performing one or more elements of method 600 and / or method 1000. Such an apparatus may be, for example, an apparatus of a UE (such as the wireless device 1302 being a UE, as described herein).

[0097] Embodiments contemplated herein include one or more non-transitory computer-readable media that include instructions that, when executed by one or more processors of an electronic device, cause the electronic device to perform one or more elements of method 600 or method 1000. The non-transitory computer-readable media may be, for example, the memory of a UE (such as the memory 1306 of the wireless device 1302 being a UE, as described herein).

[0098] Embodiments contemplated herein include an apparatus that includes logical components, modules, or circuits for performing one or more elements of method 600 or method 1000. Such an apparatus may be, for example, an apparatus of a UE (such as the wireless device 1302 being a UE, as described herein).

[0099] Embodiments contemplated herein include an apparatus that includes: one or more processors and one or more computer-readable media, the computer-readable media including instructions that, when executed by the one or more processors, cause the one or more processors to perform one or more elements of method 600 or method 1000. The apparatus can be, for example, an apparatus of a UE (such as the wireless device 1302 as a UE, as described herein).

[0100] Embodiments contemplated herein include a signal as described in or related to one or more elements of method 600 or method 1000.

[0101] Embodiments contemplated herein include a computer program or computer program product that includes instructions, where execution of the program by a processor causes the processor to perform one or more elements of method 600 or method 1000. The processor can be a processor of a UE (such as the processor 1304 of the wireless device 1302 as a UE, as described herein). The instructions can be, for example, located in the processor and / or on a memory of the UE (such as the memory 1306 of the wireless device 1302 as a UE, as described herein).

[0102] Embodiments contemplated herein include an apparatus that includes components for performing one or more elements of method 700 or method 1100. The apparatus can be, for example, an apparatus of a base station (such as the network device 1318 as a base station, as described herein).

[0103] Embodiments contemplated herein include one or more non-transitory computer-readable media that include instructions that, when executed by one or more processors of an electronic device, cause the electronic device to perform one or more elements of method 700 or method 1100. The non-transitory computer-readable media can be, for example, a memory of a base station (such as the memory 1322 of the network device 1318 as a base station, as described herein).

[0104] Embodiments contemplated herein include an apparatus that includes logic components, modules, or circuits for performing one or more elements of method 700 or method 1100. The apparatus can be, for example, an apparatus of a base station (such as the network device 1318 as a base station, as described herein).

[0105] The embodiments contemplated herein include an apparatus that includes: one or more processors and one or more computer-readable media including instructions that, when executed by the one or more processors, cause the one or more processors to perform one or more elements of method 700 or method 1100. The apparatus can be, for example, an apparatus of a base station (such as network device 1318 that is a base station, as described herein).

[0106] The embodiments contemplated herein include a signal as described in or related to one or more elements of method 700 or method 1100.

[0107] The embodiments contemplated herein include a computer program or computer program product that includes instructions, where execution of the program by a processing element causes the processing element to perform one or more elements of method 700 or method 1100. The processor can be a processor of a base station (such as processor 1320 of network device 1318 that is a base station, as described herein). The instructions can be, for example, located in and / or on a memory of the base station (such as memory 1322 of network device 1318 that is a base station, as described herein).

[0108] For one or more embodiments, at least one component among the components stated in one or more of the foregoing figures can be configured to perform one or more operations, techniques, processes, and / or methods as described herein. For example, a baseband processor as described herein in connection with one or more of the foregoing figures can be configured to operate according to one or more of the examples stated herein. As another example, circuitry associated with a UE, a base station, a network element, etc. as described above in connection with one or more of the foregoing figures can be configured to operate according to one or more of the examples stated herein.

[0109] Unless otherwise explicitly stated, any of the foregoing embodiments can be combined with any other embodiment (or combination of embodiments). The foregoing description of one or more specific implementations provides illustration and description, but is not intended to be exhaustive or to limit the scope of the embodiments to the precise forms disclosed. Modifications and variations are possible in light of the above teachings, or may be acquired from practice of various embodiments.

[0110] Embodiments and specific implementations of the systems and methods described herein can include various operations, which can be embodied in machine-executable instructions to be executed by a computer system. The computer system can include one or more general-purpose or special-purpose computers (or other electronic devices). The computer system can include hardware components that include specific logic components for performing the operations; or can include a combination of hardware, software, and / or firmware.

[0111] It should be recognized that the systems described herein include descriptions of specific embodiments. These embodiments can be combined into a single system, partially combined into other systems, divided into multiple systems, or otherwise partitioned or combined. In addition, it is contemplated that the parameters, attributes, aspects, etc. of one embodiment can be used in another embodiment. For clarity, these parameters, attributes, aspects, etc. are described in only one or more embodiments, and it should be recognized that, unless explicitly stated herein, these parameters, attributes, aspects, etc. can be combined with or substituted for the parameters, attributes, aspects, etc. of another embodiment.

[0112] It is well known that the use of personally identifiable information should follow privacy policies and practices that are recognized as meeting or exceeding industry or government requirements for maintaining user privacy. Specifically, personally identifiable information data should be managed and processed to minimize the risk of inadvertent or unauthorized access or use, and the nature of the authorized use should be clearly explained to the user.

[0113] Although the foregoing has been described in considerable detail for purposes of clarity, it will be apparent that certain changes and modifications can be made without departing from the principles of the invention. It should be noted that there are many alternative ways of implementing both the processes and apparatuses described herein. Accordingly, the embodiments of the invention should be regarded as illustrative rather than restrictive, and the specification is not limited to the details given herein but may be modified within the scope and equivalents of the appended claims.

Claims

1. A method for a user equipment (UE), the method comprises: receiving, from a network node, an SRS configuration including a sounding reference signal (SRS)-resource set, the SRS-resource set including a plurality of SRS-resources configured as a set, wherein a plurality of SRS ports are distributed over more than one SRS-resource of the set; transmitting SRS from each SRS port included in the plurality of SRS-resources of the set; receiving, from the network node, feedback based on the SRS from each SRS port; and configuring transmission from one or more ports based on the feedback.

2. The method according to claim 1, wherein the set includes two SRS-resources, each SRS-resource being mapped to four ports such that the set includes eight ports.

3. The method according to claim 1, wherein the SRS-resource set includes a second set of SRS-resources, wherein the second set of SRS-resources includes a plurality of SRS ports of a second panel distributed over more than one SRS-resource of the second set.

4. The method according to claim 1, wherein the feedback includes transmitting a precoder matrix indicator (TPMI), wherein, in order to map the TPMI to the SRS ports, the SRS ports of the plurality of SRS-resources in the set are concatenated based on the order of the plurality of SRS-resources in the SRS configuration.

5. The method according to claim 1, wherein the plurality of SRS-resources are grouped into two sets based on the order of the plurality of SRS-resources in the SRS configuration, wherein each set contains an equal or nearly equal number of the plurality of SRS-resources.

6. The method according to claim 5, wherein the feedback includes an SRS resource indicator (SRI) field, wherein a first set of SRS-resources is mapped to SRI = 0, and a second set of SRS-resources is mapped to SRI = 1.

7. The method according to claim 1, wherein the SRS configuration sets the use of the SRS-resource set to antenna switching, and the plurality of SRS ports of the plurality of SRS-resources are transmit ports for sounding an equal number of receive ports.

8. A user equipment (UE), the UE comprises: a processor; and a memory storing instructions which, when executed by the processor, configure the UE to: receive, from a network node, an SRS configuration including a sounding reference signal (SRS)-resource set, the SRS-resource set including a plurality of SRS-resources configured as a set, wherein a plurality of SRS ports are distributed over more than one SRS-resource of the set; transmit SRS from each SRS port included in the plurality of SRS-resources of the set; receive, from the network node, feedback based on the SRS from each SRS port; and configure transmission from one or more ports based on the feedback.

9. The UE according to claim 8, wherein the set comprises two SRS-resources, each SRS-resource being mapped to four ports such that the set comprises eight ports.

10. The UE according to claim 8, wherein the SRS-resource set comprises a second set of SRS-resources, wherein the second set of SRS-resources comprises a plurality of SRS ports of a second panel distributed over more than one SRS-resource of the second set.

11. The UE according to claim 8, wherein the feedback comprises transmitting a precoder matrix indicator (TPMI), wherein, in order to map the TPMI to the SRS ports, the SRS ports of the plurality of SRS-resources in the set are cascaded based on the order of the plurality of SRS-resources in the SRS configuration.

12. The UE according to claim 8, wherein the plurality of SRS-resources are grouped into two sets based on the order of the plurality of SRS-resources in the SRS configuration, wherein each set contains an equal or almost equal number of the plurality of SRS-resources.

13. The UE according to claim 12, wherein the feedback comprises an SRS resource indicator (SRI) field, wherein a first set of SRS-resources is mapped to SRI = 0, and a second set of SRS-resources is mapped to SRI = 1.

14. A method for a network node, the method comprising: transmitting to a user equipment (UE) an SRS configuration comprising a set of sounding reference signal (SRS)-resources, the set of SRS-resources comprising a plurality of SRS-resources configured as a set, wherein a plurality of SRS ports are distributed over more than one SRS-resource of the set; receiving from the UE an SRS from each SRS port comprised in the plurality of SRS-resources of the set; and transmitting feedback to the UE based on the SRS from each SRS port.

15. The method according to claim 14, wherein the set comprises two SRS-resources, each SRS-resource being mapped to four ports such that the set comprises eight ports.

16. The method according to claim 14, wherein the SRS-resource set comprises a second set of SRS-resources, wherein the second set of SRS-resources comprises a plurality of SRS ports of a second panel distributed over more than one SRS-resource of the second set.

17. The method according to claim 14, wherein the feedback comprises transmitting a precoder matrix indicator (TPMI), wherein, in order to map the TPMI to the SRS ports, the SRS ports of the plurality of SRS-resources in the set are cascaded based on the order of the plurality of SRS-resources in the SRS configuration.

18. The method according to claim 14, wherein the plurality of SRS-resources are grouped into two sets based on the order of the plurality of SRS-resources in the SRS configuration, wherein each set contains an equal or almost equal number of the plurality of SRS-resources.

19. The method according to claim 18, wherein the feedback comprises a sounding reference signal (SRS) resource indicator (SRI) field, wherein a first set of SRS - resources is mapped to SRI = 0, and a second set of SRS - resources is mapped to SRI = 1.

20. The method according to claim 18, wherein the SRS configuration sets the use of the SRS - resource set to antenna switching, and the plurality of SRS ports of the plurality of SRS - resources are transmit ports for sounding an equal number of receive ports.

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