Sounding reference signal configuration for phase offset calibration

Abstract

In accordance with example embodiments of the invention there is at least a method and apparatus to perform communicating a configuration message for a phase offset calibration measurement process comprising a sounding reference signal transmission for an uplink phase offset calibration measurement and a channel state information reference signal transmission portion for a downlink phase offset calibration measurement, wherein the phase offset calibration configuration is using one of a dedicated sounding reference signal or non-dedicated sounding reference signal, and wherein based on the downlink phase offset calibration measurement, at least one channel state information reference signal for each individual antenna port from more than one transmission or reception point are indicated for downlink channel state information acquisition.

Description

[0001] SOUNDING REFERENCE SIGNAL CONFIGURATION FOR PHASE OFFSET CALIBRATION

[0002] CROSS-REFERENCE TO RELATED APPLICATION:

[0003]

[0001] This application claims priority to, and the benefit of, US Provisional Application No. 63 / 680712, filed August 8, 2024, which is hereby incorporated by reference in its entirety.

[0004] TECHNICAL FIELD:

[0005]

[0002] The teachings in accordance with the exemplary embodiments of this invention relate generally to enable reuse of a sounding reference signal configuration and, more specifically, relate to reuse of a sounding reference signal configuration for phase offset calibration with antenna switching.

[0006] BACKGROUND:

[0007]

[0003] This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.

[0008]

[0004] Certain abbreviations that may be found in the description and / or in the Figures are herewith defined as follows:

[0009] CJT Coherent Joint Transmission

[0010] FDD Frequency Division Duplex

[0011] TDD Time Division Duplex gNB gNodeB

[0012] MRT Maximum Ratio Transmission

[0013] NW Network

[0014] PC Phase Offset

[0015] SRS Sounding Reference Signal

[0016] TDD Time Division Duplex

[0017] TRP Transmission / Reception Points

[0018] UE User Equipment

[0019]

[0005] Some example embodiments of the invention relate to Coherent Joint Transmission for Massive MIMO in a TDD system where the CSI is acquired by exploiting UL-DL channel reciprocity.

[0020]

[0006] Massive MIMO is a key component for the 5G and for the emerging 6G. One of the current directions of development is the cooperative joint transmission (CJT). In cooperative transmission a set of one or more TRPs is able to transmit coherently to UEs served in a network area. In the future, this could evolve to more general deployment like cell-free massive MIMO in which several TRPs might cooperate to transmit improving the network capacity and vanishing the effect of capacity drop in cell-edges.

[0007] Example embodiments of this invention proposes a method and apparatus for improvements in at least these operations.

[0021] SUMMARY:

[0022]

[0008] This section contains examples of possible implementations and is not meant to be limiting.

[0023]

[0009] In another example aspect of the invention, there is an apparatus, such as a user equipment side apparatus, comprising: at least one processor; and at least one non-transitory memory storing instructions, that when executed by the at least one processor, cause the apparatus at least to: receive a configuration message for a phase offset calibration measurement process comprising a sounding reference signal transmission for an uplink phase offset calibration measurement and a channel state information reference signal transmission portion for a downlink phase offset calibration measurement; wherein the configuration message comprises at least one sounding reference signal antenna port and at least one channel state information reference signal antenna port with a mapping between the at least one sounding reference signal antenna ports and the at least one channel state information reference signal antenna ports, and wherein the at least on sounding reference signal antenna port belongs to one of a dedicated sounding reference signal or non-dedicated sounding reference signal; and based on the configured phase offset calibration measurement process, indicate at least one channel state information reference signal antenna port from more than one transmission or reception point for downlink channel state information acquisition.

[0024]

[0010] In still another example aspect of the invention, there is a method, comprising: receiving a configuration message for a phase offset calibration measurement process comprising a sounding reference signal transmission for an uplink phase offset calibration measurement and a channel state information reference signal transmission portion for a downlink phase offset calibration measurement; wherein the configuration message comprises at least one sounding reference signal antenna port and at least one channel state information reference signal antenna port with a mapping between the at least one sounding reference signal antenna ports and the at least one channel state information reference signal antenna ports, and wherein the at least on sounding reference signal antenna port belongs to one of a dedicated sounding reference signal or non-dedicated sounding reference signal; and based on the configured phase offset calibration measurement process, indicating at least one channel state information reference signal antenna port from more than one transmission or reception point for downlink channel state information acquisition.

[0025] [Oil] A further example embodiment is an apparatus and a method comprising the apparatus and the method of the previous paragraphs, wherein configuration message comprises an indicator to identify the non-dedicated sounding reference signal that is being used for the sounding reference signal transmission for the uplink phase offset calibration measurement, wherein the non-dedicated sounding reference signal for the sounding reference signal transmission for the uplink phase offset calibration measurement is based on a previously configured sounding reference signal configuration, wherein the configuration message indicates which antenna ports of the non-dedicated sounding reference signal are to be used for the downlink phase offset calibration measurement based on the channel state information reference signal configured for the phase offset calibration measurement process, wherein the previously configured sounding reference signal is configured for downlink channel state information acquisition, wherein the configuration message comprises information needed to specify how to use the non-dedicated sounding reference signal for channel state information reference signal measurement portion of the phase offset calibration measurement process, wherein the downlink phase offset calibration measurement is determined based on the mapping between the at least one sounding reference signal antenna ports and the at least one channel state information reference signal antenna ports, wherein the at least one sounding reference signal antenna port is used for uplink phase offset calibration measurements for a communication using a network device in a communication network, wherein based on more than one channel state information reference signal port to be used for the phase offset measurements, the configuration is indicating at least one channel state information reference signal port to be used for the channel state information reference signal measurement portion of the phase offset calibration measurement process, and / or wherein the downlink phase offset calibration measurement is for a phase offset measurement for each of different ones of the more than one transmission or reception point.

[0026]

[0012] A non-transitory computer-readable medium storing program code, the program code executed by at least one processor to perform at least the method as described in the paragraphs above.

[0027]

[0013] In yet another example aspect of the invention, there is an apparatus comprising: means for receiving a configuration message for a phase offset calibration measurement process comprising a sounding reference signal transmission for an uplink phase offset calibration measurement and a channel state information reference signal transmission portion for a downlink phase offset calibration measurement; wherein the configuration message comprises at least one sounding reference signal antenna port and at least one channel state information reference signal antenna port with a mapping between the at least one sounding reference signal antenna ports and the at least one channel state information reference signal antenna ports, and wherein the at least on sounding reference signal antenna port belongs to one of a dedicated sounding reference signal or non-dedicated sounding reference signal; and means, based on the configured phase offset calibration measurement process, for indicating at least one channel state information reference signal antenna port from more than one transmission or reception point for downlink channel state information acquisition.

[0028]

[0014] In accordance with the example embodiments as described in the paragraph above, at least the means for receiving and indicating comprises a network interface, and computer program code stored on a computer-readable medium and executed by at least one processor.

[0029]

[0015] In another example aspect of the invention, there is an apparatus, such as a network side apparatus, comprising: at least one processor; and at least one non-transitory memory storing instructions, that when executed by the at least one processor, cause the apparatus at least to: communicate a configuration message for a phase offset calibration measurement process comprising a sounding reference signal transmission for an uplink phase offset calibration measurement and a channel state information reference signal transmission portion for a downlink phase offset calibration measurement, wherein the phase offset calibration configuration is using one of a dedicated sounding reference signal or non-dedicated sounding reference signal, and wherein based on the downlink phase offset calibration measurement, at least one channel state information reference signal for each individual antenna port from more than one transmission or reception point are indicated for downlink channel state information acquisition.

[0030]

[0016] In still another example aspect of the invention, there is a method, comprising: communicating a configuration message for a phase offset calibration measurement process comprising a sounding reference signal transmission for an uplink phase offset calibration measurement and a channel state information reference signal transmission portion for a downlink phase offset calibration measurement, wherein the phase offset calibration configuration is using one of a dedicated sounding reference signal or non-dedicated sounding reference signal, and wherein based on the downlink phase offset calibration measurement, at least one channel state information reference signal for each individual antenna port from more than one transmission or reception point are indicated for downlink channel state information acquisition.

[0031]

[0017] A further example embodiment is an apparatus and a method comprising the apparatus and the method of the previous paragraphs, wherein the configuration message comprises an indicator to identify the non-dedicated sounding reference signal that is being used for the sounding reference signal transmission for the uplink phase offset calibration measurement, wherein the non-dedicated sounding reference signal for the sounding reference signal transmission for the uplink phase offset calibration measurement is based on a previously configured sounding reference signal configuration for a sounding reference signal transmission portion of the phase offset calibration configuration, wherein the configuration message indicates which antenna ports of the non-dedicated sounding reference signal are to be used for the downlink phase offset calibration measurement based on the channel state information reference signal configured for the phase offset calibration measurement process, wherein the previously configured sounding reference signal is configured for downlink channel state information acquisition, wherein the configuration message comprises information needed to specify how to use the non-dedicated sounding reference signal for the phase offset calibration measurement process, wherein the at least one sounding reference signal antenna port is used for uplink phase offset calibration measurements for a communication using a network device in a communication network, wherein based on more than one channel state information reference signal port to be used for the phase offset measurements, the configuration is indicating at least one channel state information reference signal port to be used for the channel state information reference signal measurement of the phase offset calibration measurement process, and / or wherein the downlink phase offset calibration measurement is for a phase offset measurements for each of different ones of the more than one transmission or reception point

[0032]

[0018] In yet another example aspect of the invention, there is an apparatus comprising: means for communicating a configuration message for a phase offset calibration measurement process comprising a sounding reference signal transmission for an uplink phase offset calibration measurement and a channel state information reference signal transmission portion for a downlink phase offset calibration measurement, wherein the phase offset calibration configuration is using one of a dedicated sounding reference signal or non-dedicated sounding reference signal, and wherein based on the downlink phase offset calibration measurement, at least one channel state information reference signal for each individual antenna port from more than one transmission or reception point are indicated for downlink channel state information acquisition.

[0033]

[0019] In accordance with the example embodiments as described in the paragraph above, at least the means for communicating and indicating comprises a network interface, and computer program code stored on a computer-readable medium and executed by at least one processor.

[0034]

[0020] A communication system comprising the user equipment side apparatus and the network side apparatus performing operations as described above.

[0035] BRIEF DESCRIPTION OF THE DRAWINGS:

[0036]

[0021] The above and other aspects, features, and benefits of various embodiments of the present disclosure will become more fully apparent from the following detailed description with reference to the accompanying drawings, in which like reference signs are used to designate like or equivalent elements. The drawings are illustrated for facilitating better understanding of the embodiments of the disclosure and are not necessarily drawn to scale, in which:

[0037]

[0022] FIG. 1 A shows an illustration of the sense of reference signals and the channel acquisition as it done in UL with SRS or DL with CSI-RS and CSI feedback;

[0038]

[0023] FIG. 1 B shows an illustration of the recovery of the channel phase difference of a TRP with respect to a reference;

[0039]

[0024] FIG. 2 shows an illustration of a typical XTYR antenna switching scheme, in the example 2T4R;

[0040]

[0025] FIG. 3 shows an illustration of SRS antenna selection and mapping when the xTyR has nondedicated resource for SRS and it reuses the SRS for channel acquisition;

[0041]

[0026] FIG. 4 shows a general illustration of SRS antenna selection configuration prior to performing PO measurements;

[0042]

[0027] FIG. 5 shows a specific illustration of NW driven SRS antenna selection and configuration prior to perform PO measurements;

[0028] FIG. 6 shows a specific illustration of UE driven SRS antenna selection and configuration prior to perform PO measurements;

[0043]

[0029] FIG. 7 shows a high level block diagram of various devices used in carrying out various aspects of the invention; and

[0044]

[0030] FIG. 8A and FIG. 8B each show a method in accordance with example embodiments of the invention which may be performed by an apparatus.

[0045] DETAILED DESCRIPTION:

[0046]

[0031] In example embodiments of this invention there is proposed at least a method and apparatus to enable reuse of a sounding reference signal configuration for antenna switching for phase offset calibration.

[0032] As similarly stated above, the technical context of the invention is Coherent Joint Transmission for Massive MIMO in a TDD system where the CSI is acquired by exploiting UL-DL channel reciprocity.

[0047]

[0033] As similarly stated above, massive MIMO is a key component for the 5G and for the emerging 6G. One of the current directions of development is the cooperative joint transmission (CJT). In cooperative transmission a set of one or more TRPs is able to transmit coherently to UEs served in a network area. In the future, this could evolve to more general deployment like cell-free massive MIMO in which several TRPs might cooperate to transmit improving the network capacity and vanishing the effect of capacity drop in celledges.

[0048]

[0034] Currently Rel. 19 MIMO and CSI is studying further enhancements in the previous framework proposed by Rel. 18 CJT. These enhancements are focused to solve issues related to the frequency and time alignments in a non-ideal backhaul and the hardware misalignments. The work item covers both the TDD and FDD aspects. As it is well known, in a FDD system, the downlink (DL) and uplink (UL) channels are located in different frequency bands and the mutual reciprocity cannot be directly assumed. In such case, a quantised CSI feedback coming from the UE after measuring CSI-RS from one or more TRP is reported to the NW. However, in a TDD system, DL and UL channel can be considered mutually reciprocal because they share the same transmission band, and the duplexing is done by alternation of the downlink and uplink transmission processes. The channel acquisition is done by using sounding reference signals (SRS) transmitted from the UE toward the NW. The sense of SRS in UL and CSI-RS in DL are illustrated in FIG. 1 .

[0035] For a single TRP transmission scheme, even after calibration a left-over channel phase misalignment may exist between the hardware for uplink and downlink transmission. For single TRP transmission, this leftover misalignment can be neglected during PDSCH transmission as it can be corrected during the reception stage. However, if the transmission comes from Multiple TRPs coherently transmitting, it would be difficult to identify the channel phase offsets (PO) for each TRP, which will degrade the ability to perform coherent transmission with the multiple TRPs.

[0036] Herein is discussed the necessary configuration steps of SRS ports for the PO calibration and their coexistence with the existing SRS based channel acquisition for TDD systems.

[0049]

[0037] FIG. 1 . Illustration of the sense of reference signals and the channel acquisition as it done in UL with SRS or DL with CSI-RS and CSI feedback.

[0050]

[0038] In the FIG. 2, there is illustrated a basic example of DL / UL calibration for 2 TRPs, i.e. the TRP i with respect to a reference TRP. Without loss of generality in a wideband case for a single port calibration, and for the reference TRP and the TRP i, it may be desired to obtain the respective ratios of the measured signals in UL and DL in each TRP, i.e., YUL; ref / YDL; ref=ejeref YUL;i / YDLj = ej0irespectively. For being able to do this, there is needed to have the measurements in DL and UL. The UL measurement can be obtained from a UE transmitting a single SRS port measured at each TRP, and similarly in DL the UE could measure the DL channel from each TRP from the CSI-RS as measured on the same single port that was used to transmit the SRS. As illustrated in FIG. 2 it is possible to recover the channel phase difference between the 2 TRPs, i.e. ej^ref~ei)by measuring the received downlink signals and obtaining a ratio of YDL,ieJ<Pi ref ejei / YDL, refeJerefto get the composite phase angle e~j<Pi’refej^eref~ei)which includes the expected phase shift ej<Pi’ref between two TRPs with different channels. This latter can be removed if the ratio YULj / YUL refis measurable at NW side. Notice that this example might be extended for multiple UE Tx / Rx ports and multiple antennas for each TRP which could be for instance averaged. The received measurements at the UE side can be obtained from multiple independent measurements for each TRP in individual antenna ports or in combined / aggregated antenna ports or in beamformed ports.

[0051]

[0039] FIG. 2. Illustration of the recovery of the channel phase difference of a TRP with respect to a reference.

[0052]

[0040] The SRS transmission for the DL / UL calibration just described may be done with a specific SRS configuration that is dedicated to the DI / UL phase calibration process. On the other hand, the SRS for antenna switching is generally used by the gNB for acquiring the DL channel state information in TDD systems. Transmitting the SRS for antenna switching is configured with the XTYR notation, wherein a total of Y UE TX antenna ports are sounded but only X UE transmitting antenna ports are sounded at a time in each transmission occasion. Note that when the UE receives downlink transmissions (e.g., PDSCH), all Y antenna ports are available for reception all the time.

[0053]

[0041] Similarly, when SRS is used for CJT UL / DL PO calibration measurements, it is considered that the SRS transmission might be configured to use a similar-style antenna switching scheme wherein PSRSports are used and PSRS> 1 . Moreover, a total of Q SRS resources can be used for PO measurements which are also cycled through by using a xTyR switching scheme and thus Q = y / x and y = PSRS. Notice that 1 ) the x, y for the SRS configuration for PO measurements might be different from the X, Y used in the SRS configuration for SRS for antenna switching for DL CSI acquisition and 2) the two process, i.e. PO measurements and UL / DL channel acquisition are not necessarily configured with the same SRS antenna switching configuration, and they might be applied in different time instants and therefore can be completely independent processes. In other words, nothing prevents the system from having a fully dedicated SRS measurement configuration exclusively used for UL / DL PO and another separate SRS measurement procedure for DL CSI acquisition (SRS for antenna switching). A natural question is whether an SRS configuration could be used simultaneously for both DL CSI acquisition and the CJT UL / DL PO calibration measurements, which would save some system overhead by not requiring an additional SRS transmission from the UE. In other words, can both the PO and DL-CSI-RS measurements be calculated simultaneously from the same SRS for antenna switching configuration, i.e. the SRS for PO is a non-dedicated procedure, meaning that it is not dedicated solely for PO calibration. The purpose of this invention report is to propose a SRS configuration framework for UL / DL PO in the context of CJT calibration specifications for Rel. 19.

[0054]

[0042] During the previous RAN 1 # 117 meeting and as described in the agreements below, the discussion has addressed the subject of SRS port configuration for PO compensation in the framework of Rel. 19 CJT calibration. Then for RAN 1 # 118, the new specific points to discuss are about the values of Q and PSRSand the specific details of configuration behind these values. In that direction, there are two possible perspectives as described in proposal 3.C.2 in which the SRS port selection could be carried out by the NW or the UE.

[0055]

[0043] Aqreement(RAN1#117)

[0056] For the Rel-19 aperiodic standalone CJT calibration reporting, when ReportQuantity is ‘cjtc-P’ (DL / UL phase offset).

[0057] For a given phase offset reporting configuration, the UE can be configured (via higher-layer / RRC signaling) with Q associated SRS resource(s) for antenna switching, FFS: The supported value(s) of Q The UE antenna port(s) for receiving the CSI-RS configured for phase offset measurement are same as the UE antenna port(s) for transmitting the selected / configured port(s) from the associated SRS resource(s).

[0058]

[0044] Agreement (RAN1 #117)

[0059] For the Rel-19 aperiodic standalone CJT calibration reporting, when ReportQuantity is ‘cjtc-P’ (DL / UL phase offset),

[0060] • Regarding the number of configured associated SRS resource(s) (=Q) for antenna switching xTyR, support at least Q=1 where: o the configured associated SRS resource is selected from all the y / x SRS resources and all the configured resource set(s) o FFS (by RAN1#118): whether Q>1 is also supported o FFS (by RAN1#118): the supported value(s) of x • Regarding how to determine the SRS port corresponding to the ‘reference UE antenna port’, support PSRS =1 SRS port selected from all the ports from the configured Q associated SRS resource(s) o FFS (by RAN1#118): Whether PSRS >1 is also supported

[0061] Proposal 3.C.2: For the Rel-19 aperiodic standalone CJT calibration reporting, when ReportQuantity is ‘cjtc-P’ (DL / UL phase offset), regarding how to determine the SRS port corresponding to the ‘reference UE antenna port’, support the following:

[0062] - Scheme-! . The UE is configured by NW (via higher-layer / RRC signaling) PSRS SRS port(s) selected from all the port(s) from the configured Q associated SRS resource(s) for phase offset reporting: o FFS: Exact details of configuration mechanism, o FFS: Supported value(s) of PSRS;

[0063] - Scheme2. The UE selects PSRS SRS port(s) out of all the ports across Q resources and includes the selection in the phase offset report: o FFS: Supported value(s) of PSRS, o FFS: Whether further restriction(s) to limit the time gap between the received CSI-RS and the transmitted associated SRS are needed.

[0064]

[0045] The proposal above is needed so that the UE and gNB know the exact SRS port(s) used for the linkage in 3.C.2. Scheme2 (UE driven port selection) offers an additional freedom for the UE to select the port(s) according to its implementation, while Schemel (NW driven port selection) the procedure relies on NW configuration. In some T-docs it is argued that Scheme2 facilitates NW implementation using nonprecoded CSI-RS linked with SRS. Supporting both schemes facilitates more use cases and deployment scenarios for PO report.

[0065]

[0046] From the agreements is difficult to capture all the implications that exist considering the PO calibration process and the relationship with the SRS port based channel acquisition for TDD. To consistently configure the SRS ports for both process (PO measurement and DL CSI acquisition in TDD) requires a careful study to have both the PO calibration and channel acquisition processes properly functioning.

[0066]

[0047] The problems to be solved in accordance with example embodiments of the invention include:

[0067] • How to enable reuse of a single SRS configuration for both DL channel acquisition and also for PO measurement, and also having a separate, i.e., dedicated, SRS transmission after PO measurement?

[0068] • How the ports of the antenna switching configuration xTyR for PO need to be mapped to the ports of antenna switching configuration for DL channel acquisition with XTYR? • How to configure SRS transmission for PO with antenna switching xTyR, when y = PSRS> 1, considering the configuration XTYR for SRS UL / DL CSI acquisition.

[0069]

[0048] Before describing the example embodiments as disclosed herein in detail, reference is made to FIG. 7 for illustrating a simplified block diagram of various electronic devices that are suitable for use in practicing the example embodiments of this invention.

[0070]

[0049] FIG. 7 is a block diagram of one possible and non-limiting system in which the example embodiments may be practiced.

[0071]

[0050] Turning to FIG. 7, this figure shows a block diagram of one possible and non-limiting example in which the examples may be practiced. A user equipment (UE) 110, radio access network (RAN) node 170, and network element(s) 190 are illustrated. In the example of FIG. 7, the user equipment (UE) 110 is in wireless communication with a wireless network 100. A UE is a wireless device that can access the wireless network 100. The UE 110 includes one or more processors 120, one or more memories 125, and one or more transceivers 130 interconnected through one or more buses 127. Each of the one or more transceivers 130 includes a receiver, Rx, 132 and a transmitter, Tx, 133. The one or more buses 127 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, and the like. The one or more transceivers 130 are connected to one or more antennas 128. The one or more memories 125 include computer program code 123. The UE 110 includes a merge module 140, comprising one of or both parts 140-1 and / or 140-2, which may be implemented in a number of ways. The merge module 140 may be implemented in hardware as merge module 140-1 , such as being implemented as part of the one or more processors 120. The merge module 140-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the merge module 140 may be implemented as merge module 140-2, which is implemented as computer program code 123 and is executed by the one or more processors 120. For instance, the one or more memories 125 and the computer program code 123 may be configured to, with the one or more processors 120, cause the user equipment 110 to perform one or more of the operations as described herein. The UE 110 communicates with RAN node 170 via a wireless link 111.

[0072]

[0051] The RAN node 170 in this example is a base station that provides access by wireless devices such as the UE 110 to the wireless network 100. The RAN node 170 may be, for example, a base station for 5G, also called New Radio (NR). In 5G, the RAN node 170 may be a NG-RAN node, which is defined as either a gNB or an ng-eNB. A gNB is a node providing NR user plane and control plane protocol terminations towards the UE, and connected via the NG interface to a 5GC (such as, for example, the network element(s) 190). The ng-eNB is a node providing E-UTRA user plane and control plane protocol terminations towards the UE, and connected via the NG interface to the 5GC. The NG-RAN node may include multiple gNBs, which may also include a central unit (CU) (gNB-CU) 196 and distributed unit(s) (DUs) (gNB-DUs), of which DU 195 is shown. Note that the DU may include or be coupled to and control a radio unit (RU). The gNB- CU is a logical node hosting radio resource control (RRC), SDAP and PDCP protocols of the gNB or RRC and PDCP protocols of the en-gNB that controls the operation of one or more gNB-DUs. The gNB-CU terminates the F1 interface connected with the gNB-DU. The F1 interface is illustrated as reference 198, although reference 198 also illustrates a link between remote elements of the RAN node 170 and centralized elements of the RAN node 170, such as between the gNB-CU 196 and the gNB-DU 195. The gNB-DU is a logical node hosting RLC, MAC and PHY layers of the gNB or en-gNB, and its operation is partly controlled by gNB-CU. One gNB-CU supports one or multiple cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the F1 interface 198 connected with the gNB-CU. Note that the DU 195 is considered to include the transceiver 160, e.g., as part of a RU, but some examples of this may have the transceiver 160 as part of a separate RU, e.g., under control of and connected to the DU 195. The RAN node 170 may also be an eNB (evolved NodeB) base station, for LTE (long term evolution), or any other suitable base station or node.

[0073]

[0052] The RAN node 170 includes one or more processors 152, one or more memories 155, one or more network interfaces (N / W l / F(s)) 161 , and one or more transceivers 160 interconnected through one or more buses 157. Each of the one or more transceivers 160 includes a receiver, Rx, 162 and a transmitter, Tx, 163. The one or more transceivers 160 are connected to one or more antennas 158. The one or more memories 155 include computer program code 153. The CU 196 may include the processor(s) 152, memories 155, and network interfaces 161. Note that the DU 195 may also contain its own memory / memories and processor(s), and / or other hardware, but these are not shown.

[0074]

[0053] The RAN node 170 includes a merge module 150, comprising one of or both parts 150-1 and / or 150- 2, which may be implemented in a number of ways. The merge module 150 may be implemented in hardware as merge module 150-1 , such as being implemented as part of the one or more processors 152. The merge module 150-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the merge module 150 may be implemented as merge module 150-2, which is implemented as computer program code 153 and is executed by the one or more processors 152. For instance, the one or more memories 155 and the computer program code 153 are configured to, with the one or more processors 152, cause the RAN node 170 to perform one or more of the operations as described herein. Note that the functionality of the merge module 150 may be distributed, such as being distributed between the DU 195 and the CU 196, or be implemented solely in the DU 195.

[0075]

[0054] The one or more network interfaces 161 communicate over a network such as via the links 176 and 131 . Two or more gNBs 170 may communicate using, e.g., link 176. The link 176 may be wired or wireless or both and may implement, for example, an Xn interface for 5G, an X2 interface for LTE, or other suitable interface for other standards.

[0055] The one or more buses 157 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, wireless channels, and the like. For example, the one or more transceivers 160 may be implemented as a remote radio head (RRH) 195 for LTE or a distributed unit (DU) 195 for gNB implementation for 5G, with the other elements of the RAN node 170 possibly being physically in a different location from the RRH / DU, and the one or more buses 157 could be implemented in part as, for example, fiber optic cable or other suitable network connection to connect the other elements (e.g., a central unit (CU), gNB-CU) of the RAN node 170 to the RRH / DU 195. Reference 198 also indicates those suitable network link(s).

[0076]

[0056] It is noted that description herein indicates that “cells” perform functions, but it should be clear that equipment which forms the cell may perform the functions. The cell makes up part of a base station. That is, there can be multiple cells per base station. For example, there could be three cells for a single carrier frequency and associated bandwidth, each cell covering one-third of a 360 degree area so that the single base station’s coverage area covers an approximate oval or circle. Furthermore, each cell can correspond to a single carrier and a base station may use multiple carriers. So if there are three 120 degree cells per carrier and two carriers, then the base station has a total of 6 cells.

[0077]

[0057] The wireless network 100 may include a network element or elements 190 that may include core network functionality, and which provides connectivity via a link or links 181 with a further network, such as a telephone network and / or a data communications network (e.g., the Internet). Such core network functionality for 5G may include access and mobility management function(s) (AMF(S)) and / or user plane functions (UPF(s)) and / or session management function(s) (SMF(s)). Such core network functionality for LTE may include MME (Mobility Management Entity) / SGW (Serving Gateway) functionality. These are merely example functions that may be supported by the network element(s) 190, and note that both 5G and LTE functions might be supported. The RAN node 170 is coupled via a link 131 to the network element 190. The link 131 may be implemented as, e.g., an NG interface for 5G, or an S1 interface for LTE, or other suitable interface for other standards. The network element 190 includes one or more processors 175, one or more memories 171 , and one or more network interfaces (N / W l / F(s)) 180, interconnected through one or more buses 185. The one or more memories 171 include computer program code 173. The one or more memories 171 and the computer program code 173 are configured to, with the one or more processors 175, cause the network element 190 to perform one or more operations.

[0078]

[0058] The wireless network 100 may implement network virtualization, which is the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network. Network virtualization involves platform virtualization, often combined with resource virtualization. Network virtualization is categorized as either external, combining many networks, or parts of networks, into a virtual unit, or internal, providing network-like functionality to software containers on a single system. Note that the virtualized entities that result from the network virtualization are still implemented, at some level, using hardware such as processors 152 or 175 and memories 155 and 171 , and also such virtualized entities create technical effects.

[0079]

[0059] The computer readable memories 125, 155, and 171 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The computer readable memories 125, 155, and 171 may be means for performing storage functions. The processors 120, 152, and 175 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multi-core processor architecture, as non-limiting examples. The processors 120, 152, and 175 may be means for performing functions, such as controlling the UE 110, RAN node 170, network element(s) 190, and other functions as described herein.

[0080]

[0060] In general, the various embodiments of the user equipment 110 can include, but are not limited to, cellular telephones such as smart phones, tablets, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback appliances having wireless communication capabilities, Internet appliances permitting wireless Internet access and browsing, tablets with wireless communication capabilities, as well as portable units or terminals that incorporate combinations of such functions.

[0081]

[0061] One or more of merge modules 140-1 , 140-2, 150-1 , and 150-2 may be configured to implement high level syntax for a compressed representation of neural networks based on the examples described herein. Computer program code 173 may also be configured to implement high level syntax for a compressed representation of neural networks based on the examples described herein.

[0082]

[0062] Further, the various embodiments of any of these devices can be used with a UE vehicle, a High Altitude Platform Station, or any other such type node associated with a terrestrial network or any drone type radio or a radio in aircraft or other airborne vehicle or a vessel that travels on water such as a boat.

[0083]

[0063] As similarly stated above, problems to be solved in accordance with example embodiments of the invention include:

[0084]

[0064] How to enable reuse of SRS for both DL channel acquisition and also for PO measurement, and also having separate, i.e. , dedicated, SRS transmission after PO measurement?

[0085]

[0065] How the ports of the antenna switching configuration xTyR for PO needs to be mapped to the ports of antenna switching configuration for DL channel acquisition with XTYR?

[0066] How to leverage SRS configured for antenna switching (DL CSI acquisition), configured with XTYR, and reuse those SRS transmissions for PO where the PO effectively uses a xTyR configuration with y = PSRS1 (where the configuration of the SRS UL / DL CSI acquisition was XTYR.

[0086]

[0067] A goal of the present invention is to establish the procedures of configuration necessary for the SRS port configuration related to PO measurement when reusing SRS for DL CSI acquisition rather than having a separate dedicated SRS for PO measurement. There is described the problem of configuring the PO measurement process when the SRS portion of that process is an existing SRS that is configured for some purpose other than PO measurement (e.g., configured for DL CSI acquisition). The configuration message of the PO calibration process or the specifications must then indicate which of the SRS ports of the SRS for DL CSI acquisition shall be used for the SRS portion of the PO calibration process. Additional embodiments cover SRS port selection and configuration aspects for PO measurement and can be carried out using any of the two schemes suggested in proposal 3.C.2, i.e. NW driven or UE driven. The elements to cover are the following:

[0087] I) The necessary antenna mapping and identification of SRS ports xTyR needed for PO measurement and the linkage with the XTYR scheme for SRS configured for DL channel acquisition. Such identification may be carried out in one of several ways. For example:

[0088] * indicating the antenna indexes of the y = PSRSports selected out of the Y UE antenna ports available for channel acquisition,

[0089] « Alternatively a bitmap of size Y with y = PSRSindicated ports could be also used,

[0090] « In the case in which x, y and X, Y the antenna switching scheme for PO and Channel acquisition are the same, then the mapping and identification would not be necessary, meaning that a one-to-one correspondence can be assumed;

[0091] II) Selection and indication procedure of the SRS ports which are going to be used also as UE receiving ports to be used to receive the CSI-RS or TRS during the DL measurements for PO estimation:

[0092] « The UE ports might be selected in the UE, for instance, based on CSI-RS / TRS measurements effectuated first and reported by the UE. Then these antenna ports can be included by the NW in the configuration message for PO calibration (where the configuration message could be a MAC-GE or RRC configuration message),

[0093] • The UE ports might be also selected after a SRS measurement for UL / DL channel acquisition or in a dedicated SRS measurement for PO and then configured by the NW and included in the RRC configuration message; III) The mechanism to indicate that a dedicated SRS procedure with associated resources to effectuate PO measurements needs to be activated, OR otherwise the SRS for UL / DL channel acquisition is going to be reused for PO measurement and no dedicated SRS procedure nor resource is being allocated. This indication can also be included in the RRC configuration of the PO measurements and informed to UE.

[0094]

[0068] Example embodiments of the invention propose enhanced configuration methodologies to support phase-offset compensation in TDD-based CJT. In TDD-based CJT, the DL CSI acquisition for the CJT transmission is based on SRS, which (in contrast to feed-back-based CSI-acquisition (e.g., Type II CSI for CJT)) cannot account for any phase differences between multiple TRPs. Given how multiple TRPs are likely to have different TX phases, Rel-19 is developing the signaling support for compensating for these phase offsets at different TRPs that are performing CJT transmission. The compensation involves measuring the UL / DL phase offset (PO) at each TRP, and the details of the overall phase-offset calibration mechanism are beyond the scope of this invention.

[0095]

[0069] There are two main methodologies that are envisioned for performing the UL / DL phase offset (PO) compensation in TDD-based CJT: PO Cal Method 1 : MRT-precoded CSI-RS and PO Cal Method 2: non- MRT-precoded CSI-RS. The proposals in this invention report are aimed at supporting both of these PO Cal methods. Both of these Cal methods involve four main steps: (0) the gNB configuring the PO measurement and reporting, (1) the UE transmitting SRS from one or more UE TX ports, and (2) the gNB transmits CSI- RS with one or more ports (3) the UE sends a PO report.

[0096]

[0070] In the following, two calibration methodologies are dealt with separately and describe the configuration methodologies that are proposed in accordance with example embodiments of the invention for the two schemes. For each calibration methodology, the calibration scheme must firstly be described and then describe the associated configuration enhancements in accordance with example embodiments of the invention.

[0097] PO Cal Method 1 : MRT-precoded CSI-RS solution:

[0098]

[0071] This PO Cal method is based on the gNB calculating a Max Ratio Transmission (MRT) precoder based on the SRS measurements from a single UE TX port. For transmitting to a UE with a single receive antenna, the MRT precoder corresponds to the Hermitian of the channel vector H for the UE’s receive antenna. For the PO Cal Method 1 , the following (general) steps are as follows: (The description is for the case of one UE SRS TX port and one corresponding CSI-RS port.):

[0099] (1) UE transmits SRS from one UE TX port. The gNB computes an UL gain measurement based on an Max Ratio Combining (MRC) receive processing RX weight vector for that UE SRS TX port,

[0100] (2) gNB receives the SRS from the UE and computes an MRT precoding vector for the UE TX port that sent the SRS. Note that the MRT precoding vector must be identical to the MRC receiving vector, (3) The gNB transmits precoded CSI-RS that is precoded with the MRT precoding vector computed in step (2): A single precoded CSI-RS port is formed for the UE TX port that sent the SRS in step (1),

[0101] (4) The UE computes a DL gain measurement for the CSI-RS port transmitted in step (3): The DL gain measurement for the CSI-RS port must be done with the UE RX port that matches the UE TX port that sent the SRS that the MRT precoding for the CSI-RS port is based on,

[0102] (5) The UE sends the DL gain measurement to the gNB,

[0103] (6) The calculations needed to determine the PC compensation can be determined by the gNB based on the calculated UL gain measurement and reported DL gain measurement.

[0104]

[0072] Some comments on PC CAL method 1 are as follows:

[0105] • The SRS in Step (1) must precede in time the transmission of the CSI-RS in Step (3) because the precoding of the CSI-RS in Step (2) is based on the SRS received in Step (1),

[0106] • The above steps can be extended to enable the collection of multiple sets of UL and DL gain measurements for e.g. to leverage averaging for improved PC compensation performance. Given the use of MRT-precoded CSI-RS, if it is desired that the UE send back more than one gain measurement (e.g., to take advantage of averaging, etc.), then there must be a 1-1 correspondence between each MRT-precoded CSI-RS port and the UE antenna port that transmitted the SRS that the MRT precoding was based on.

[0107] PO Cal Method 2: Non-MRT precoded CSI-RS:

[0108]

[0073] This PO Cal method is similar to PO Cal Method 1 , but the precoding of the CSI-RS does not need to be based on MRT and therefore does not need to be UE-specific. Any arbitrary precoding vector can be used to precode the CSI-RS as long as the gNB performs its UL gain measurements with the same RX weight vector that it uses to precode the CSI-RS port that is used by the UE to make the DL gain measurement.

[0109]

[0074] The steps of this method are similar to those in method 1 and are listed as follows:

[0110] (1) UE transmits SRS from one UE TX port. The gNB computes an UL gain measurement for the UE TX port based on a pre-determined RX weight vector;

[0111] (2) The gNB transmits precoded CSI-RS that is precoded with a precoding vector that is identical to the pre-determined RX weight vector used to make the UL gain measurement in Step (1);

[0112] (3) The UE computes a DL gain measurement for the CSI-RS port transmitted in step (2): The DL gain measurement for the CSI-RS port must be done with the UE RX port that matches the UE TX port that sent the SRS in step (1);

[0113] (4) The UE sends the DL gain measurements to the gNB; (5) The calculations needed to determine the PO compensation can be determined by the gNB based on the calculated UL gain measurement and the reported DL gain measurements. The details of this compensation are beyond the scope of this invention report.

[0114]

[0075] Some comments on PO CAL method 2 are as follows:

[0115] • The SRS in Step (1) does not have to precede in time the transmission of the CSI-RS in Step (3) because the precoding of the CSI-RS in Step (2) is not based on the SRS received in Step (1). There can either be the SRS transmitted first in time or the CSI-RS transmitted first in time;

[0116] • As with PO Method 1 , the above steps for PO Method 2 can be extended to enable the collection of multiple pairs of UL and DL gain measurements e.g. to leverage averaging for improved PO compensation performance. The extension to multiple sets of UL and DL gain measurements is more flexible with Method 2 due to the use of precoded CSI-RS that is not UE specific. There are options for extending to multiple pairs of DL and UL gain measurements: o Single CSI-RS port, multiple SRS ports:

[0117] ■ The UE makes multiple DL gain measurements from the single CSI-RS port, one for each receive antenna port,

[0118] ■ The gNB makes multiple corresponding UL gain measurements for each UE SRS port, where each UL gain measurement is made with the beamforming RX weight vector that formed the single CSI-RS port; o Multiple CSI-RS ports, single SRS port:

[0119] ■ The UE makes multiple DL gain measurements with a single RX antenna port, one gain measurement for each CSI-RS port,

[0120] ■ The gNB makes multiple corresponding UL gain measurements for the single UE TX port, where each UL gain measurement is made with the RX beamforming weight vector that was used to transmit the CSI-RS port,

[0121] ■ for the single SRS port, one for each receive weight vector corresponding to the transmit weight used to precode the CSI-RS port. The gNB will compute the corresponding UL gain measurement from the single SRS port but each are done with the receive weight vector that corresponds to the transmit weight vector that formed the corresponding CSI-RS port; o Multiple CSI-RS ports, multiple SRS ports: In this case, there can be many ways to form multiple sets of DL gain measurements and UL gain measurements, and those ways are simple extensions of the previous three sub-bullets. There can be a 1-1 correspondence between SRS port and CSI-RS port as in Method 1 , or there can be one-to-many (first sub- bullet above), many-to one (second sub-bullet above), or straightforward combinations thereof.

[0122] Configuring options for the PO Cal Process

[0123]

[0076] In the following, there is discussed the options for configuring and signaling the PO CAL process. The description generally applies to either PO method 1 or PO method 2, and any differences that apply to method 1 versus method 2 will be pointed out. In general, the gNB decides whether to use method 1 or method 2, and because the measurements sent back from the UE are the same in both methods, the UE does not need to know which method the gNB is using.

[0124]

[0077] First, the PO calibration process will require a configuration message to tell the UE how to transmit the SRS, what CSI-RS to measure, and what gain measurements to send in the measurement report (e.g., how many DL gain measurements, etc.). In the PO calibration process, a key requirement is that the UE antenna port used to transmit a single-port SRS must be the same UE antenna port that is used to measure the downlink channel from the precoded CSI-RS.

[0125]

[0078] Two main aspects are configured for PO measurement:

[0126] • Configuring the CSI-RS: o UE-specific CSI-RS configuration: If Method 1 is used where the CSI-RS is UE-specific (e.g., MRT-precoded according to the UL channel measured on SRS), the configuration message will configure a UE specific CSI-RS. For Method 1 , there cannot be a CSI-RS that is used by other UEs for other purposes, so the CSI-RS for Method 1 must be UE-specific. If Method 2 is used, the CSI-RS can be UE specific, but a non-UE specific alternative may be preferred instead, o Non-UE specific CSI-RS configuration: If Method 2 is used, the CSI-RS can be non-UE specific, in which case any single- or multi-port CSI-RS can be used for the PO process, o The configuration message will contain a pointer to the CSI-RS that is to be used for the PO measurements. If the CSI-RS is multi-port, then the configuration message will indicate which ports of the CSI-RS ports are to be used for the PO measurements;

[0127] • Configuring SRS: two cases for configuring the SRS are as follows: o Dedicated SRS for PO measurement: in this case there is an SRS that is dedicated specifically for PO measurements and is configured much like SRS for antenna switching is configured, o Non-dedicated SRS: In this case, there is re-used a previously-configured SRS configuration for the SRS transmission portion of the PO Cal process: For example, there can leverage an SRS for DL CSI acquisition (SRS for antenna switching in the NR spec). As another example, there can be leveraging of an SRS for UL CSI acquisition (SRS for codebook-based UL). It is denoted this option as non-dedicated SRS to denote how the SRS is configured for another purpose (a purpose other than PO measurement), but is being re-used for the SRS portion of the PO CAL methodology. Therefore, the need for a separate dedicated SRS for PO measurements can be reduced or eliminated with this method.

[0128]

[0079] A key aspect of this invention is the use of non-dedicated SRS for the SRS portion of the PO calibration process. Non-dedicated SRS means SRS that is configured for some purpose other than PO calibration (e.g., SRS for DL CSI acquisition, SRS for UL CSI acquisition, etc.). In the PO calibration process, a key requirement is that the UE antenna port used to transmit a single-port SRS must be the same UE antenna port that is used to measure the downlink channel from the precoded CSI-RS.

[0129]

[0080] If SRS for PO is leveraged, then the configuration of the PO process will link together the dedicated SRS and the CSI-RS to be used for the PO measurements, and the configuration of the dedicated SRS and the CSI-RS can be done in a consistent manner.

[0130]

[0081] However, if non-dedicated SRS is used, the configuration message must at least contain a pointer to or an identifier of the non-dedicated SRS that is being used for the PO portion of the PO process. Another issue is that the antenna switching configuration in the non-dedicated SRS may be different from the SRS measurements are needed for the SRS portion of the PO calibration method. As a result, there can be ambiguities over how to re-use the non-dedicated SRS for the PO calibration method. Therefore, the configuration message must also contain and / or identify the information needed to specify how to use the non-dedicated SRS for the PO calibration methodology. This information is in the form of a determination / indication of which SRS ports of the non-dedicated SRS are to be used in the PO calibration process, which (as described above) requires that those SRS ports are to be used to measure the DL channel from the CSI- RS transmission portion of the PO calibration process.

[0131]

[0082] In general, the SRS antenna switching configuration in 5G NR is denoted xTyR, which means SRS is transmitted over y UE ports with x ports transmitting SRS at a time. This needs Q=y / x time instances (resources) are needed to cycle over the y UE ports. For the PO calibration process, the variable PSRSdenotes the number of SRS ports leveraged in the PO calibration process. For configuring what SRS is needed for PO, it can be assumed a configuration denoted xTyR. For the non-dedicated SRS, a configuration denoted XTYR is assumed.

[0132]

[0083] The non-dedicated SRS (e.g., SRS for DL CSI acquisition) is configured with some XTYR antenna switching configuration, which means that the gNB will indicate which y = PSRSports of the non-dedicated SRS should be used for the DL PO gain measurements (from the DL CSI-RS), where Y > y = PSRSports and X > x in the most general case. Moreover, as stated before, the selected SRS ports used by the gNB for the UL PO measurement must be the same as the UE ports used for the CSI-RS measurements in order to have a consistent PO measurement. As a result, there can be a need to indicate to the UE which SRS ports of the non-dedicated SRS are to be used for the DL part of the PO measurement. Example embodiments of the invention are leveraging non-dedicated SRS.

[0133]

[0084] In the above approach, the UE is told in the configuration message which UE ports to use, and there is no provision for adaptive selection of which SRS ports to use. An alternative approach is to allow for the adaptive selection of the UE’s SRS ports to be used on RX for the DL gain measurements of the PO process. This approach is mostly relevant when the UE is configured to transmit from all of its SRS ports for nondedicated SRS for CSI acquisition, which is a detail not described in the agreements from RAN1#117. In this approach the UE can be told by the gNB to leverage some number of the SRS ports on RX for the DL gain measurement portion of the PO process, and the UE must indicate specifically which ones were used.

[0134] SRS Antenna port correspondence and mapping:

[0135]

[0085] Notice that in general, for the non-dedicated SRS measurements cases (i.e. a single SRS configuration is used for both DL channel acquisition and for PO measurements), it is necessary to indicate which SRS antenna ports of the SRS for DL CSI acquisition are to be also used for the DL part of the PO measurement, and there needs to be a 1-1 correspondence between the UE ports for SRS transmission and the UE ports for receiving the CSI-RS for the PO measurements . For that a bitmap or indication of the antenna indexes used is needed. This is illustrated in with an example in FIG. 3, in which there are 8 UE antennas. For SRS channel acquisition for instance X = 2 and Y = 8, which yields 2T8R. Notice that Y is not necessarily the total amount of UE ports, but maybe a subset, e.g. the SRS channel acquisition is split in independent groups associated to independent PDSCH transmissions. Out of the Y antenna ports for SRS channel acquisition, the SRS transmitted from such antenna’s ports may be re-used in full or partially for the PO calibration process. In the case when xTyR and XTYR are the same switching scheme, then no mapping or correspondence indications are needed. However in the case in which just a fraction of these ports may be used, for instance, having SRS measurement for PO and use only, y = PSRS= 2 or 4 ports and x= 1 or 2 ports to cycle through the PSRSports by means of a 1T2R or 2T4R antenna scheme. The antenna selection and corresponding bitmaps are depicted. Alternatively to a bitmap, the antennas indexes could be retrieved and expressed using traditional or combinatorial indexing binary coding.

[0136]

[0086] FIG. 3 shows an illustration of SRS antenna selection and mapping when the xTyR has nondedicated resource for SRS and it reuses the SRS for channel acquisition.

[0137]

[0087] On the other hand, for the case with a dedicated SRS measurement for PO this mapping is not necessary (i.e., an additional indication to the UE is not needed) as the SRS ports for PO are not part of an SRS for antenna switching for DL channel acquisition. However, it might still be necessary to indicate the antenna ports used to transmit the SRS for PO as they must be consistent with the UE antenna ports used to receive the CSI-RS for PO, e.g. as in the Non-MRT precoded CSI-RS case (method-2). Notice that anyway this antenna selection indication is not related to the XTYR antenna switching used for SRS for DL channel acquisition.

[0138] Necessary SRS antenna ports configuration signaling:

[0139]

[0088] In order to have the PO measurement procedure configured before it could be carried out, it is necessary to configure the following things:

[0140] - The gNB can determine whether to activate a SRS dedicated resource for PO measurement (i.e., dedicated SRS resource) or utilize (re-use) the SRS resource from the SRS for DL channel acquisition (i.e. non dedicated SRS resource) or perhaps both in some cases,

[0141] - For non-dedicated SRS, the gNB selects which SRS port(s) of the CSI-RS for DL CSI acquisition are going to be selected to be used for the PO process.

[0142] - For MRT-precoded CSI-RS, the gNB must configure the SRS for PO from the UE, where the SRS for PO is either SRS for PO (dedicated) or SRS for DL CSI acquisition (non-dedicated),

[0143] The SRS must be configured to be transmitted before the MRT-precoded CSI-RS because the MRT for the precoded CSI-RS is computed based on the SRS,

[0144] - For non-MRT precoded CSI-RS, the gNB has a choice in either configuring the CSI-RS before the SRS or the SRS before the CSI-RS,

[0145] - Finally, if a SRS non-dedicated resource has been set the mapping and correspondence between xTyR (SRS antenna switching for PO) and XTYR (SRS antenna switching for DL channel acquisition must be determined and indicated to the UE.

[0146]

[0089] A general sequence diagram is given in FIG. 4. In this figure, the process being depicted is the process of managing how the SRS antenna selection is carried out prior to performing the PO measurements. There is grouped the main steps in 4 basic stages: 1) initial configuration of the SRS antenna ports to be used for PO measurements; 2) UE transmits the SRS for PO according to the configured antenna selection with the restrictions given for Q, x, y, PSRS. 3) in the case of non-dedicated SRS resources for PO the mapping between xTyR and XTXR antenna switching schemes is needed; and 4) in which the PO compensation configuration is determined and the PO measurements are carried out.

[0147]

[0090] Furthermore, there is provided the specific diagrams for the NW driven and UE driven SRS antenna selection.

[0148]

[0091] In the NW driven case, as depicted in FIG. 5:

[0149] - Step 2: the SRS antennas are selected and indicated by the gNB after being measured at the NW side based on SRS sounding generated by the UE,

[0150] - Step 3: After that, it is up to the NW not only selecting the SRS antenna ports, but also determining the mapping of the xTyR for PO measurements with respect to the XTYR used for the SRS for DL channel acquisition Nonetheless such a mapping is only relevant for the non-dedicated SRS case where the SRS is jointly used for both PO and channel acquisition,

[0151] - Step 4: Later on the PO compensation configuration with the SRS antenna selection and other parameters, (including the SRS antenna mapping message for the case with non-dedicated SRS resources) is provided to the UE. The mapping and antenna selection received at UE side is useful not only for SRS configuration but for ensuring consistency during CSI-RS measurements. Finally, the PO measurements can be carried out by means of SRS, i.e. , with dedicated or non-dedicated resources and also the corresponding CSI-RS measurements.

[0152]

[0092] On the other hand, in FIG. 6 there is illustrated the case with UE driven SRS port selection. As noticed the main differences with the NW driven case happens in step 2 and step 3, as the SRS antenna selection and mapping between xTyR and XTXR antenna switching schemes happens at the UE, and then UE reports this information to the NW. Finally step 4 would proceed very similarly to the NW driven case.

[0153]

[0093] FIG. 8A and FIG. 8B each show a method in accordance with example embodiments of the invention which may be performed by an apparatus.

[0154]

[0094] FIG. 8A illustrates operations which may be performed by a device such as, but not limited to, a device such as a network device (e.g., the UE 110 as in FIG. 7). As shown in block 810 of FIG. 8A there is receiving a configuration message for a phase offset calibration measurement process comprising a sounding reference signal transmission for an uplink phase offset calibration measurement and a channel state information reference signal transmission portion for a downlink phase offset calibration measurement. As shown in block 820 of FIG. 8A wherein the configuration message comprises at least one sounding reference signal antenna port and at least one channel state information reference signal antenna port with a mapping between the at least one sounding reference signal antenna ports and the at least one channel state information reference signal antenna ports. As shown in block 830 of FIG. 8A wherein the at least one sounding reference signal antenna port belongs to one of a dedicated sounding reference signal or nondedicated sounding reference signal. Then as shown in block 840 of FIG. 8A there is, based on the configured phase offset calibration measurement process, indicate at least one channel state information reference signal antenna port from more than one transmission or reception point for downlink channel state information acquisition.

[0155]

[0095] In accordance with the example embodiments as described in the paragraph above, wherein configuration message comprises an indicator to identify the non-dedicated sounding reference signal that is being used for the sounding reference signal transmission for the uplink phase offset calibration measurement.

[0096] In accordance with the example embodiments as described in the paragraphs above, wherein the non-dedicated sounding reference signal for the sounding reference signal transmission for the uplink phase offset calibration measurement is based on a previously configured sounding reference signal configuration.

[0097] In accordance with the example embodiments as described in the paragraphs above, wherein the configuration message indicates which antenna ports of the non-dedicated sounding reference signal are to be used for the downlink phase offset calibration measurement based on the channel state information reference signal configured for the phase offset calibration measurement process.

[0156]

[0098] In accordance with the example embodiments as described in the paragraphs above, wherein the previously configured sounding reference signal is configured for downlink channel state information acquisition.

[0157]

[0099] In accordance with the example embodiments as described in the paragraphs above, configuration message comprises information needed to specify how to use the non-dedicated sounding reference signal for channel state information reference signal measurement portion of the phase offset calibration measurement process.

[0158]

[0100] In accordance with the example embodiments as described in the paragraphs above, wherein the downlink phase offset calibration measurement is determined based on the mapping between the at least one sounding reference signal antenna ports and the at least one channel state information reference signal antenna ports.

[0159]

[0101] In accordance with the example embodiments as described in the paragraphs above, wherein the at least one sounding reference signal antenna port is used for uplink phase offset calibration measurements for a communication using a network device in a communication network.

[0160]

[0102] In accordance with the example embodiments as described in the paragraphs above, wherein the at least one sounding reference signal antenna port is used for an uplink phase offset calibration measurement for a network device in a communication network.

[0161]

[0103] In accordance with the example embodiments as described in the paragraphs above, wherein based on more than one channel state information reference signal port to be used for the phase offset measurements, the configuration is indicating at least one channel state information reference signal port to be used for the channel state information reference signal measurement portion of the phase offset calibration measurement process.

[0162]

[0104] In accordance with the example embodiments as described in the paragraphs above, wherein the downlink phase offset calibration measurement is for a phase offset measurement for each of different ones of the more than one transmission or reception point.

[0163]

[0105] A non-transitory computer-readable medium (Memory(ies) 125 as in FIG. 7) storing program code (Computer Program Code 123 and / or Config Module 140-2 as in FIG. 7), the program code executed by at least one processor (Processor(s) 120 and / or Module 140-1 as in FIG. 7) to perform the operations as at least described in the paragraphs above.

[0164]

[0106] In accordance with an example embodiment of the invention as described above there is an apparatus comprising: means for receiving (Memory(ies) 125, Computer Program Code123, RA Module 140-2, and Processors 120, RA Module 140-1 as in FIG. 7) a configuration message for a phase offset calibration measurement process comprising a sounding reference signal transmission for an uplink phase offset calibration measurement and a channel state information reference signal transmission portion for a downlink phase offset calibration measurement; wherein the configuration message comprises at least one sounding reference signal antenna port and at least one channel state information reference signal antenna port with a mapping between the at least one sounding reference signal antenna ports and the at least one channel state information reference signal antenna ports, and wherein the at least on sounding reference signal antenna port belongs to one of a dedicated sounding reference signal or non-dedicated sounding reference signal; and means, based on the configured phase offset calibration measurement process, for indicating (Memory(ies) 125, Computer Program Code123, RA Module 140-2, and Processors 120, RA Module 140-1 as in FIG. 7) at least one channel state information reference signal antenna port from more than one transmission or reception point for downlink channel state information acquisition.

[0165]

[0107] In the example aspects according to the paragraph above, wherein at least the means for using, and / or sending comprises a non-transitory computer readable medium [Memory(ies) as in FIG. 7] encoded with a computer program [Computer Program Code 123 and / or Config Module 140-2 as in FIG. 7] executable by at least one processor [Processor(s) 120 and / or Module 140-1 as in FIG. 7],

[0166]

[0108] FIG. 8B illustrates operations which may be performed by a device such as, but not limited to, a device such as a network device (e.g., the RAN Node 170 as in FIG. 7). As shown in block 850 of FIG. 8B there is communicating a configuration message for a phase offset calibration measurement process comprising a sounding reference signal transmission for an uplink phase offset calibration measurement and a channel state information reference signal transmission portion for a downlink phase offset calibration measurement. As shown in block 860 of FIG. 8B wherein the phase offset calibration configuration is using one of a dedicated sounding reference signal or non-dedicated sounding reference signal. Then as shown in block 870 of FIG. 8B wherein based on the downlink phase offset calibration measurement, at least one channel state information reference signal for each individual antenna port from more than one transmission or reception point are indicated for downlink channel state information acquisition.

[0167]

[0109] In accordance with the example embodiments as described in the paragraph above, wherein the configuration message comprises an indicator to identify the non-dedicated sounding reference signal that is being used for the sounding reference signal transmission for the uplink phase offset calibration measurement.

[0110] In accordance with the example embodiments as described in the paragraphs above, wherein the non-dedicated sounding reference signal for the sounding reference signal transmission for the uplink phase offset calibration measurement is based on a previously configured sounding reference signal configuration for a sounding reference signal transmission of the phase offset calibration configuration.

[0168] [Hl] In accordance with the example embodiments as described in the paragraphs above, wherein the configuration message indicates which antenna ports of the non-dedicated sounding reference signal are to be used for the downlink phase offset calibration measurement based on the channel state information reference signal configured for the phase offset calibration measurement process.

[0169]

[0112] In accordance with the example embodiments as described in the paragraphs above, wherein the previously configured sounding reference signal is configured for downlink channel state information acquisition.

[0170]

[0113] In accordance with the example embodiments as described in the paragraphs above, configuration message comprises information needed to specify how to use the non-dedicated sounding reference signal for the phase offset calibration measurement process.

[0171]

[0114] In accordance with the example embodiments as described in the paragraphs above, wherein the at least one sounding reference signal antenna port is used for uplink phase offset calibration measurements for a communication using a network device in a communication network.

[0172]

[0115] In accordance with the example embodiments as described in the paragraphs above, wherein based on more than one channel state information reference signal port to be used for the phase offset measurements, the configuration is indicating at least one channel state information reference signal port to be used for the channel state information reference signal measurement portion of the phase offset calibration measurement process.

[0173]

[0116] In accordance with the example embodiments as described in the paragraphs above, wherein the downlink phase offset calibration measurement is for a phase offset measurements for each of different ones of the more than one transmission or reception point.

[0174]

[0117] A non-transitory computer-readable medium (Memory(ies) 155 as in FIG. 7) storing program code (Computer Program Code 153 and / or Config Module 150-2 as in FIG. 7), the program code executed by at least one processor (Processor(s) 196 and / or Module 150-1 as in FIG. 7) to perform the operations as at least described in the paragraphs above.

[0175]

[0118] In accordance with an example embodiment of the invention as described above there is an apparatus comprising: means for communicating (Memory(ies) 155, Computer Program Code153, RA Module 153, and Processors 196, RA Module 150-1 as in FIG. 7) a configuration message for a phase offset calibration measurement process comprising a sounding reference signal transmission for an uplink phase offset calibration measurement and a channel state information reference signal transmission portion for a downlink phase offset calibration measurement, wherein the phase offset calibration configuration is using one of a dedicated sounding reference signal or non-dedicated sounding reference signal, and wherein based on the downlink phase offset calibration measurement, at least one channel state information reference signal for each individual antenna port from more than one transmission or reception point are indicated (Memory(ies) 155, Computer Program Code153, RA Module 153, and Processors 196, RA Module 150-1 as in FIG. 7) for downlink channel state information acquisition.

[0176]

[0119] In the example aspects according to the paragraph above, wherein at least the means for using, and / or sending comprises a non-transitory computer readable medium [Memory(ies) 155 as in FIG. 7] encoded with a computer program [Computer Program Code 153 and / or Config Module 150-2 as in FIG. 7] executable by at least one processor [Processor(s) 196 and / or Module 150-1 as in FIG. 7],

[0177]

[0120] It is noted that computer-implemented inventions (Cll) may be claimed as apparatus claims, method claims, and software claims. In some jurisdictions, such as in Europe, signal claims can also be made. In the U.S., a software claim must be claimed as a non-transitory computer program product or a non-transitory computer readable medium.

[0178]

[0121] The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal ) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

[0179]

[0122] In other jurisdictions, a software claim can be claimed as a computer program, a data structure, and / or a computer readable medium.

[0180]

[0123] Further, in accordance with example embodiments of the invention there is circuitry for performing operations in accordance with example embodiments of the invention as disclosed herein. This circuitry can include any type of circuitry including content coding circuitry, content decoding circuitry, processing circuitry, image generation circuitry, data analysis circuitry, etc.). Further, this circuitry can include discrete circuitry, application-specific integrated circuitry (ASIC), and / or field-programmable gate array circuitry (FPGA), etc. as well as a processor specifically configured by software to perform the respective function, or dual-core processors with software and corresponding digital signal processors, etc.). Additionally, there are provided necessary inputs to and outputs from the circuitry, the function performed by the circuitry and the interconnection (perhaps via the inputs and outputs) of the circuitry with other components that may include other circuitry in order to perform example embodiments of the invention as described herein.

[0181]

[0124] In accordance with example embodiments of the invention as disclosed in this application this application, the “circuitry” provided can include at least one or more or all of the following:

[0182] (a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry);

[0183] (b) combinations of hardware circuits and software, such as (as applicable):

[0184] (i) a combination of analog and / or digital hardware circuit(s) with software / firmware; and

[0185] (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions, such as functions or operations in accordance with example embodiments of the invention as disclosed herein); and

[0186] (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.”

[0187]

[0125] In accordance with example embodiments of the invention, there is adequate circuitry for performing at least novel operations in accordance with example embodiments of the invention as disclosed in this application, this 'circuitry' as may be used herein refers to at least the following:

[0188] (a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry); and

[0189] (b) to combinations of circuits and software (and / or firmware), such as (as applicable): (i) to a combination of processor(s) or (ii) to portions of processor(s) / software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions); and

[0190] (c) to circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present.

[0191]

[0126] This definition of 'circuitry' applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" would also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its (or their) accompanying software and / or firmware. The term "circuitry" would also cover, for example and if applicable to the particular claim element, a baseband integrated circuit or applications processor integrated circuit for a mobile phone or a similar integrated circuit in a server, a cellular network device, or other network device.

[0192]

[0127] In general, the various embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects of the invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0193]

[0128] Embodiments of the inventions may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

[0129] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. All of the embodiments described in this Detailed Description are exemplary embodiments provided to enable persons skilled in the art to make or use the invention and not to limit the scope of the invention which is defined by the claims.

[0194]

[0130] The foregoing description has provided by way of exemplary and non-limiting examples a full and informative description of the best method and apparatus presently contemplated by the inventors for carrying out the invention. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings of example embodiments of this invention will still fall within the scope of this invention.

[0195]

[0131] It should be noted that the terms "connected," "coupled," or any variant thereof, mean any connection or coupling, either direct or indirect, between two or more elements, and may encompass the presence of one or more intermediate elements between two elements that are "connected" or "coupled" together. The coupling or connection between the elements can be physical, logical, or a combination thereof. As employed herein two elements may be considered to be "connected" or "coupled" together by the use of one or more wires, cables and / or printed electrical connections, as well as by the use of electromagnetic energy, such as electromagnetic energy having wavelengths in the radio frequency region, the microwave region and the optical (both visible and invisible) region, as several non-limiting and non-exhaustive examples.

[0196]

[0132] Furthermore, some of the features of the preferred embodiments of this invention could be used to advantage without the corresponding use of other features. As such, the foregoing description should be considered as merely illustrative of the principles of the invention, and not in limitation thereof.

Claims

CLAIMSWhat is claimed is:1 . An apparatus, comprising: at least one processor; and at least one memory storing instructions, that when executed by the at least one processor, cause the apparatus at least to: receive a configuration message for a phase offset calibration measurement process comprising a sounding reference signal transmission for an uplink phase offset calibration measurement and a channel state information reference signal transmission for a downlink phase offset calibration measurement; wherein the configuration message comprises at least one sounding reference signal antenna port and at least one channel state information reference signal antenna port with a mapping between the at least one sounding reference signal antenna ports and the at least one channel state information reference signal antenna ports, and wherein the at least one sounding reference signal antenna port belongs to one of a dedicated sounding reference signal or non-dedicated sounding reference signal; and based on the configured phase offset calibration measurement process, indicate at least one channel state information reference signal antenna port from more than one transmission or reception point for downlink channel state information acquisition.

2. The apparatus of claim 1 , wherein configuration message comprises an indicator to identify the non-dedicated sounding reference signal that is being used for the sounding reference signal transmission for the uplink phase offset calibration measurement.

3. The apparatus of claim 2, wherein the non-dedicated sounding reference signal for the sounding reference signal transmission for the uplink phase offset calibration measurement is based on a previously configured sounding reference signal configuration.

4. The apparatus of claim 2, wherein the configuration message indicates which antenna ports of the non-dedicated sounding reference signal are to be used for the downlink phase offset calibration measurement based on the channel state information reference signal configured for the phase offset calibration measurement process.

5. The apparatus of claim 2, wherein the downlink phase offset calibrationmeasurement is determined based on the mapping between the at least one sounding reference signal antenna ports and the at least one channel state information reference signal antenna ports.

6. The apparatus of claim 1 , wherein the at least one sounding reference signal antenna port is used for phase offset measurements for a communication using a network device in a communication network.

7. The apparatus of claim 1 , wherein based on more than one channel state information reference signal port to be used for the phase offset measurements, the configuration is indicating at least one channel state information reference signal port to be used for the channel state information reference signal measurement of the phase offset calibration measurement process.

8. The apparatus of claim 1 , wherein the downlink phase offset calibration measurement is for a phase offset measurement for each of different ones of the more than one transmission or reception point.

9. A method, comprising: receiving a configuration message for a phase offset calibration measurement process comprising a sounding reference signal transmission for an uplink phase offset calibration measurement and a channel state information reference signal transmission portion for a downlink phase offset calibration measurement; wherein the configuration message comprises at least one sounding reference signal antenna port and at least one channel state information reference signal antenna port with a mapping between the at least one sounding reference signal antenna ports and the at least one channel state information reference signal antenna ports, and wherein the at least on sounding reference signal antenna port belongs to one of a dedicated sounding reference signal or non-dedicated sounding reference signal; and based on the configured phase offset calibration measurement process, indicating at least one channel state information reference signal antenna port from more than one transmission or reception point for downlink channel state information acquisition.

10. An apparatus, comprising: at least one processor; and at least one memory storing instructions, that when executed by the at least one processor, cause the apparatus at least to:communicate a configuration message for a phase offset calibration measurement process comprising a sounding reference signal transmission for an uplink phase offset calibration measurement and a channel state information reference signal transmission for a downlink phase offset calibration measurement, wherein the phase offset calibration configuration is using one of a dedicated sounding reference signal or non-dedicated sounding reference signal, and wherein based on the downlink phase offset calibration measurement, at least one channel state information reference signal for each individual antenna port from more than one transmission or reception point are indicated for downlink channel state information acquisition.11 . The apparatus of claim 10, wherein the configuration message comprises an indicator to identify the non-dedicated sounding reference signal that is being used for the sounding reference signal transmission for the uplink phase offset calibration measurement.

12. The apparatus of claim 11 , wherein the non-dedicated sounding reference signal for the sounding reference signal transmission for the uplink phase offset calibration measurement is based on a previously configured sounding reference signal configuration for a sounding reference signal transmission of the phase offset calibration configuration.

13. The apparatus of claim 12, wherein the previously configured sounding reference signal is configured for downlink channel state information acquisition.

14. The apparatus of claim 11 , wherein the configuration message indicates which antenna ports of the non-dedicated sounding reference signal are to be used for the downlink phase offset calibration measurement based on the channel state information reference signal configured for the phase offset calibration measurement process.

15. The apparatus of claim 10, wherein the downlink phase offset calibration measurement is determined based on the mapping between the at least one sounding reference signal antenna ports and the at least one channel state information reference signal antenna ports.

16. The apparatus of claim 10, wherein the at least one sounding reference signal antenna port is used for phase offset measurements for a communication using a network device in a communication network.

17. The apparatus of claim 10, wherein based on more than one channel state information reference signal port to be used for the phase offset measurements, the configuration is indicating at least one channel state information reference signal port to be used for the channel state information reference signal measurement portion of the phase offset calibration measurement process.

18. The apparatus of claim 10, wherein the downlink phase offset calibration measurement is for a phase offset measurements for each of different ones of the more than one transmission or reception point.

19. A method, comprising: communicating a configuration message for a phase offset calibration measurement process comprising a sounding reference signal transmission for an uplink phase offset calibration measurement and a channel state information reference signal transmission portion for a downlink phase offset calibration measurement, wherein the phase offset calibration configuration is using one of a dedicated sounding reference signal or non-dedicated sounding reference signal, and wherein based on the downlink phase offset calibration measurement, at least one channel state information reference signal for each individual antenna port from more than one transmission or reception point are indicated for downlink channel state information acquisition.

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