WO2019197044A1

WO2019197044A1 - Channel state information reciprocity support for beam based operation

Info

Publication number: WO2019197044A1
Application number: PCT/EP2018/059586
Authority: WO
Inventors: Juha Pekka Karjalainen; Timo Koskela; Mihai Enescu; Sami-Jukka Hakola; Lars Dalsgaard; Jorma Johannes Kaikkonen
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2018-04-13
Filing date: 2018-04-13
Publication date: 2019-10-17
Anticipated expiration: 2020-10-13

Abstract

There are provided measures for channel state information reciprocity support for beam based operation. Such measures exemplarily comprise configuring at least one uplink reference signal set with uplink resources for beam management, configuring a terminal with an uplink reference signal resource for uplink beam management out of said at least one uplink reference signal set, receiving, from said terminal, an uplink reference signal transmission utilizing at least one spatial filter corresponding to said uplink reference signal resource for uplink beam management, and generating a non-codebook based precoder for downlink transmission towards said terminal based on said received uplink reference signal transmission utilizing said at least one spatial filter.

Description

Title

Channel state inform ation reciprocity support for beam based operation

Field

The present invention relates to channel state inform ation reciprocity support for beam based operation. More specifically, the present invention exemplarily relates to m easures ( including m ethods, apparatuses and computer program products) for realizing channel state inform ation reciprocity support for beam based operation in particular in relation to 3^rd Generation Partnership Project (3GPP) New Radio ( NR) .

Background

The present specification generally relates to 3GPP New Radio (NR) physical layer design in Rel1 5 and onwards. More specifically, the present specification focuses to enhance user equipm ent ( UE) m ulti-panel operation with non-beam correspondence at high carrier frequencies.

Current beam m anagem ent procedures largely rely on beam correspondence at UE, i.e. that UE can determ ine both receive ( RX) and transm it (TX) beam based on downlink ( DL) reference signal ( RS) .

All the beam indication procedures for downlink signals are relying on DL RS to be the reference RS to determ ine RX beam at the UE.

I n NR Rel- 1 5 specifications, antenna switching UE procedure is defined to enable DL channel state inform ation (CSI ) acquisition/sounding at gNB-side (gNB: gNodeB) based on uplink (UL) sounding reference signal (SRS) transmission, when a number of TX radio frequency (RF) chains associated with UE antennas/ antenna panels is less than RX RF chains at UE-side.

Figure 6 shows an example of CSI-RS based gNB TX beam identification and UL SRS antenna switching as well as demodulation reference signal (DMRS) UE procedures supported in NR Rel-15. Flere, gNB is equipped with two TX panels and UE has capability to use for reception two RX panels simultaneously and for transmission only one TX panel at the time. In particular, Figure 6 shows an example of DL CSI-RS based BM and antenna switching procedure as well as DMRS transmission with beam reciprocity.

A network has configured by radio resource control (RRC) signaling two CSI-RS sets, i.e. set 1 and set 2, with four single antenna port CSI-RS resources in each resource set for gNB TX beam identification.

For both CSI-RS sets, the higher layer parameter repetition has been configured to be OFF indicating each resource within the set to be transmitted into different spatial directions in separate orthogonal frequency-division multiplexing (OFDM) symbols. For simplicity, UE has been configured to report four strongest L1-RSRP values with CRIs via physical uplink control channel (PUCCFI). Based on a beam report, network initiates UE antenna switching procedure with two CRIs associated with the strongest L1 -RSRP values.

For this purpose, the network has configured one SRS resource set with two SRS resources with single antenna port. Flere, network has configured by higher layer parameter SRS-SpatialRelationl nfo for both SRS resources to be with CSI-RS resource indicators (CRI)s associated with the strongest reported L1-RSRP values. Based on this, UE is able to direct its UL TX beam former according to the strongest reported DL CSI-RS resources. In antenna switching, UE transmits one single port SRS resource at time instant n from TX panel 1, and at time instant n+L (L represents delay which is subject to numerology) another single port SRS resource is transmitted from TX panel 2.

Based on antenna switching, gNB can obtain knowledge of DL CSI that can be used for the computation of non-codebook based precoder for DL PDSCH transmission associated with DMRS. The network informs UE about TX beams associated with DL transmission of DMRS of physical downlink shared channel (PDSCH) via transmission configuration indicator (TCI) states. Here, TCI state associated with DMRS of PDSCH defines the strongest reported DL CSI-RS resources as a source for DMRS resources within TCI-state.

As discussed earlier, DL beam indication framework in NR Rel-15 is based on the assumption of UE beam correspondence between UL and DL beams. In other words, in NR Rel-15 based TCI-state framework, it is just possible just to use DL RS as spatial source for either other DL RS or UL RS.

As a result of this, there is a problem if UL RS is needed to be used as spatial source for DL RS. At the moment, NR Rel-15 does not provide any mechanism to support for this.

Figure 7 shows an example of SRS based UL beam management (BM) and antenna switching as well as the transmission of DL DMRS for PDSCH. Here, UL SRS based UL beam management is used to obtain UE TX beams. In particular, Figure 7 shows an example of UL SRS based BM and antenna switching procedure as well as DMRS transmission.

For this purpose, a network configures via higher layers two SRS resource sets for UL beam management, namely set 1 and set 2 with two resources in in each set. The network configures the sweeping of different UL TX beams by configuring SRS- ResourceMapping with repetition factor set to 1 for each resource with different sym bol positions.

Based on UL BM, gNB determ ines “the best” SRS resources for exam ple according to the largest m easured L1 - RSRPs at the gNB-side. Furthermore, the network configures by higher layer param eter SRS-SpatialRelation l nfo for both SRS resources for antenna switching to be associated with “best” SRI s associated with UL beam m anagem ent .

These “best” SRS resources, i.e. SRI s, are indicated for UE with PDCCH downlink control inform ation ( DCI ) form at 0_1 , to UE to be used in UL TX antenna switching. After this, DL CSI can be obtained via UE antenna switching procedure as discussed earlier.

However, the problem arises when gNB has com puted non-codebook based precoder and spatial reference for DL DMRS need to be indicated for UE. More specifically, the current DL TCI -state fram ework associated for DL TX and RX beam indication fram ework does not provide any support for defining UL SRS or any other UL RS as a spatial source for DL DMRS or any other DL RS. Therefore, UE is not able to align its RX spatial filter(s) , i.e. analog beam form er (s) , to a correction spatial direction corresponding to the transm ission of UL SRS resource(s) enabling the reception of DMRS of PDSCH.

Due to this, there is a spatial m isalignm ent between TX beams associated with DMRS of PDSCH and UE RX spatial filter(s)/beam form er(s) , leading to the com puted non-linear precoder at gNB to work inefficiently. I n other words, due to spatial m isalignm ent, DL CSI obtained via UL SRS based antenna switching does not m atch with radio channel associated with the scheduled DL DMRS transm ission.

Based on aforem entioned discussion, if the specification does not provide any UE procedure and signaling m echanism to use UL RS as a spatial source for DL RS, non-codebook based precoding cannot be supported in NR Rel-15 when UL beam management is used. The same problem arises also when only UL BM is used without any UE antenna switching procedure, for example when the number of RX RF and TX RF chains at UE-side is the same.

Hence, to harvest the system capacity merits of advanced non-codebook based DL transmission schemes in single and MU-MI MO scenarios, there is a need to fix this problem in NR Rel-15 and related specifications.

Hence, in general, there is a need to provide for channel state information reciprocity support for beam based operation.

Summary

Various exemplary embodiments of the present invention aim at addressing at least part of the above issues and/or problems and drawbacks.

Various aspects of exemplary embodiments of the present invention are set out in the appended claims.

According to an exemplary aspect of the present invention, there is provided a method comprising configuring at least one uplink reference signal set with uplink resources for beam management, configuring a terminal with an uplink reference signal resource for uplink beam management out of said at least one uplink reference signal set, receiving, from said terminal, an uplink reference signal transmission utilizing at least one spatial filter corresponding to said uplink reference signal resource for uplink beam management, and generating a non-codebook based precoder for downlink transmission towards said terminal based on said received uplink reference signal transmission utilizing said at least one spatial filter. According to an exemplary aspect of the present invention, there is provided a method comprising receiving a configuration of an uplink reference signal resource for uplink beam management out of at least one configured uplink reference signal set, and transmitting, to a network node, an uplink reference signal transmission utilizing at least one spatial filter corresponding to said uplink reference signal resource for uplink beam management.

According to an exemplary aspect of the present invention, there is provided an apparatus, the apparatus comprising at least one processor, at least one memory including computer program code, and at least one interface configured for communication with at least another apparatus, the at least one processor, with the at least one memory and the computer program code, being configured to cause the apparatus to perform: configuring at least one uplink reference signal set with uplink resources for beam management, configuring a terminal with an uplink reference signal resource for uplink beam management out of said at least one uplink reference signal set, receiving, from said terminal, an uplink reference signal transmission utilizing at least one spatial filter corresponding to said uplink reference signal resource for uplink beam management, and generating a non-codebook based precoder for downlink transmission towards said terminal based on said received uplink reference signal transmission utilizing said at least one spatial filter.

According to an exemplary aspect of the present invention, there is provided an apparatus, the apparatus comprising at least one processor, at least one memory including computer program code, and at least one interface configured for communication with at least another apparatus, the at least one processor, with the at least one memory and the computer program code, being configured to cause the apparatus to perform: receiving a configuration of an uplink reference signal resource for uplink beam management out of at least one configured uplink reference signal set, and transmitting, to a network node, an uplink reference signal transmission utilizing at least one spatial filter corresponding to said uplink reference signal resource for uplink beam management.

According to an exemplary aspect of the present invention, there is provided an apparatus, the apparatus comprising control circuitry configured to configure at least one uplink reference signal set with uplink resources for beam management, and to configure a terminal with an uplink reference signal resource for uplink beam management out of said at least one uplink reference signal set, receiving circuitry configured to receive, from said terminal, an uplink reference signal transmission utilizing at least one spatial filter corresponding to said uplink reference signal resource for uplink beam management, and generating circuitry configured to generate a non-codebook based precoder for downlink transmission towards said terminal based on said received uplink reference signal transmission utilizing said at least one spatial filter.

According to an exemplary aspect of the present invention, there is provided an apparatus, the apparatus comprising receiving circuitry configured to receive a configuration of an uplink reference signal resource for uplink beam management out of at least one configured uplink reference signal set, and transmitting circuitry configured to transmit, to a network node, an uplink reference signal transmission utilizing at least one spatial filter corresponding to said uplink reference signal resource for uplink beam management.

According to an exemplary aspect of the present invention, there is provided a computer program product comprising computer-executable computer program code which, when the program is run on a computer (e.g. a computer of an apparatus according to any one of the aforementioned apparatus-related exemplary aspects of the present invention), is configured to cause the computer to carry out the method according to any one of the aforementioned method-related exemplary aspects of the present invention. Such computer program product may comprise (or be embodied) a (tangible) computer-readable (storage) medium or the like on which the computer-executable computer program code is stored, and/or the program may be directly loadable into an internal memory of the computer or a processor thereof.

Any one of the above aspects enables at least an efficient enhancement of TCI -state based DL beam based operation at carrier frequencies above 6 GHz, and/or enables the UE to use UL SRS or any other UL RS (e.g. DMRS for data and/or control, phase tracking reference signal, PTRS) based DL CSI acquisition for non-codebook based DL transmissions as well as DL user scheduling, to thereby solve at least part of the problems and drawbacks identified in relation to the prior art.

By way of exemplary embodiments of the present invention, there is provided channel state information reciprocity support for beam based operation. More specifically, by way of exemplary embodiments of the present invention, there are provided measures and mechanisms for realizing channel state information reciprocity support for beam based operation.

Thus, improvement is achieved by methods, apparatuses and computer program products enabling/realizing channel state information reciprocity support for beam based operation.

Brief description of the drawings

In the following, the present invention will be described in greater detail by way of non-limiting examples with reference to the accompanying drawings, in which Figure 1 is a block diagram illustrating an apparatus according to exemplary embodiments of the present invention,

Figure 2 is a block diagram illustrating an apparatus according to exemplary embodiments of the present invention,

Figure 3 is a block diagram illustrating an apparatus according to exemplary embodiments of the present invention,

Figure 4 is a schematic diagram of a procedure according to exemplary embodiments of the present invention,

Figure 5 is a schematic diagram of a procedure according to exemplary embodiments of the present invention,

Figure 6 shows a schematic diagram of a spatial source determination procedure and an antenna switching procedure,

Figure 7 shows a schematic diagram of a spatial source determination procedure and an antenna switching procedure,

Figure 8 shows a schematic diagram of a spatial source determination procedure and an antenna switching procedure according to exemplary embodiments of the present invention, and

Figure 9 is a block diagram alternatively illustrating apparatuses according to exemplary embodiments of the present invention.

Detailed description of drawings and embodiments of the present invention

The present invention is described herein with reference to particular non limiting examples and to what are presently considered to be conceivable embodiments of the present invention. A person skilled in the art will appreciate that the invention is by no means limited to these examples, and may be more broadly applied.

It is to be noted that the following description of the present invention and its embodiments mainly refers to specifications being used as non-limiting examples for certain exemplary network configurations and deployments. Namely, the present invention and its embodiments are mainly described in relation to 3GPP specifications being used as non-limiting examples for certain exemplary network configurations and deployments. As such, the description of exemplary embodiments given herein specifically refers to terminology which is directly related thereto. Such terminology is only used in the context of the presented non-limiting examples, and does naturally not limit the invention in any way. Rather, any other communication or communication related system deployment, etc. may also be utilized as long as compliant with the features described herein.

Hereinafter, various embodiments and implementations of the present invention and its aspects or embodiments are described using several variants and/or alternatives. It is generally noted that, according to certain needs and constraints, all of the described variants and/or alternatives may be provided alone or in any conceivable combination (also including combinations of individual features of the various variants and/or alternatives) .

According to exemplary embodiments of the present invention, in general terms, there are provided measures and mechanisms for (enabling/realizing) channel state information reciprocity support for beam based operation.

Figure 1 is a block diagram illustrating an apparatus according to exemplary embodiments of the present invention. The apparatus may be a network node 10 such as a gNB comprising a control circuitry 11, a receiving circuitry 12, and a generating circuitry 13. The control circuitry 11 at least one uplink reference signal set with uplink resources for beam management. The control circuitry 11 further configures a terminal with an uplink reference signal resource for uplink beam management out of said at least one uplink reference signal set. The receiving circuitry 12 receives, from said terminal, an uplink reference signal transmission utilizing at least one spatial filter corresponding to said uplink reference signal resource for uplink beam management. The generating circuitry 13 generates a non codebook based precoder for downlink transmission towards said terminal based on said received uplink reference signal transmission utilizing said at least one spatial filter. Figure 4 is a schematic diagram of a procedure according to exemplary embodiments of the present invention. The apparatus according to Figure 1 may perform the method of Figure 4 but is not limited to this method. The method of Figure 4 may be performed by the apparatus of Figure 1 but is not limited to being performed by this apparatus.

As shown in Figure 4, a procedure according to exemplary embodiments of the present invention comprises an operation of configuring (S41) at least one uplink reference signal set with uplink resources for beam management, an operation of configuring (S42) a terminal with an uplink reference signal resource for uplink beam management out of said at least one uplink reference signal set, an operation of receiving (S43), from said terminal, an uplink reference signal transmission utilizing at least one spatial filter corresponding to said uplink reference signal resource for uplink beam management, and an operation of generating (S44) a non codebook based precoder for downlink transmission towards said terminal based on said received uplink reference signal transmission utilizing said at least one spatial filter.

The present invention shall not be construed as being limited to DL non codebook based transmission. Accordingly, any UL RS can be used as spatial source also for DL DMRS precoded with codebook based DL transmission. Figure 2 is a block diagram illustrating an apparatus according to exem plary embodim ents of the present invention. I n particular, Figure 2 illustrates a variation of the apparatus shown in Figure 1 . The apparatus according to Figure 2 m ay thus further com prise scheduling circuitry 21 and/or transm itting circuitry 22.

I n an em bodiment at least som e of the functionalities of the apparatus shown in Figure 1 (or 2) m ay be shared between two physically separate devices form ing one operational entity. Therefore, the apparatus m ay be seen to depict the operational entity com prising one or more physically separate devices for executing at least som e of the described processes.

According to a variation of the procedure shown in Figure 4, the at least one uplink reference signal set with uplink resources for beam m anagem ent m ay be at least one uplink sounding reference signal set with uplink resources for beam m anagem ent.

According to a variation of the procedure shown in Figure 4, the at least one uplink reference signal set with uplink resources for beam m anagem ent m ay be at least one uplink reference signal set with uplink resources for beam m anagem ent with antenna switching.

According to a variation of the procedure shown in Figure 4, exem plary additional operations are given, which are inherently independent from each other as such . According to such variation, an exem plary m ethod according to exem plary embodim ents of the present invention m ay com prise an operation of configuring a transm ission configuration indicator state for said downlink transm ission towards said term inal indicative of that said at least one uplink reference signal resource or a resource set including said uplink reference signal resource is to be used as a spatial source for downlink reference signal resource determ ination of said at least one spatial filter. According to a variation of the procedure shown in Figure 4, exemplary details of the configuring operation (configuring said transmission configuration indicator state for said downlink transmission towards said terminal) are given, which are inherently independent from each other as such.

Such exemplary configuring operation (configuring said transmission configuration indicator state for said downlink transmission towards said terminal) according to exemplary embodiments of the present invention may utilize radio resource control signaling.

According to a variation of the procedure shown in Figure 4, exemplary additional operations are given, which are inherently independent from each other as such. According to such variation, an exemplary method according to exemplary embodiments of the present invention may comprise an operation of scheduling a downlink demodulation reference signal associated with said at least one spatial filter based on said non-codebook based precoder.

According to a variation of the procedure shown in Figure 4, exemplary additional operations are given, which are inherently independent from each other as such. According to such variation, an exemplary method according to exemplary embodiments of the present invention may comprise an operation of transmitting said downlink demodulation reference signal to said terminal.

According to a variation of the procedure shown in Figure 4, exemplary details of the configuring operation (S41) are given, which are inherently independent from each other as such.

Such exemplary configuring operation (configuring said at least one uplink reference signal set) according to exemplary embodiments of the present invention may utilize radio resource control signaling. According to a variation of the procedure shown in Figure 4, the uplink reference signal resource m ay be at least one of an uplink sounding reference signal resource used for user equipm ent antenna switching or uplink beam m anagem ent, an uplink demodulation reference signal resource, and an uplink phase tracking reference signal resource.

According to a variation of the procedure shown in Figure 4, the downlink transm ission towards said term inal m ay be at least one of a downlink demodulation reference signal associated with a physical downlink shared channel, a downlink demodulation reference signal associated with a physical downlink control channel, a downlink channel state inform ation reference signal associated with channel state inform ation acquisition, a downlink channel state inform ation reference signal associated with channel state inform ation beam m anagem ent, a downlink channel state inform ation reference signal associated with fine frequency and tim e tracking, a downlink phase tracking reference signal, and a downlink demodulation reference signal associated with physical broadcast channel, physical downlink control channel and physical downlink shared channel for rem aining m inim um system inform ation , paging, other system inform ation (OSI ) and other broadcast inform ation delivery.

Figure 3 is a block diagram illustrating an apparatus according to exem plary em bodim ents of the present invention. The apparatus m ay be a term inal 30 such as a UE com prising a receiving circuitry 31 , and a transm itting circuitry 32. The receiving circuitry 31 receives a configuration of an uplink reference signal resource for uplink beam m anagem ent out of at least one configured uplink reference signal set. The transm itting circuitry 32 transm its, to a network node, an uplink reference signal transm ission utilizing at least one spatial filter corresponding to said uplink reference signal resource for uplink beam m anagem ent. Figure 5 is a schem atic diagram of a procedure according to exem plary embodim ents of the present invention. The apparatus according to Figure 3 m ay perform the m ethod of Figure 5 but is not limited to this method. The method of Figure 5 may be performed by the apparatus of Figure 3 but is not limited to being performed by this apparatus.

As shown in Figure 5, a procedure according to exemplary embodiments of the present invention comprises an operation of receiving (S51) a configuration of an uplink reference signal resource for uplink beam management out of at least one configured uplink reference signal set, and an operation of transmitting (S52), to a network node, an uplink reference signal transmission utilizing at least one spatial filter corresponding to said uplink reference signal resource for uplink beam management.

In an embodiment at least some of the functionalities of the apparatus shown in Figure 3 may be shared between two physically separate devices forming one operational entity. Therefore, the apparatus may be seen to depict the operational entity comprising one or more physically separate devices for executing at least some of the described processes.

According to a variation of the procedure shown in Figure 5, the configuration of said uplink reference signal resource for uplink beam management may be a configuration of an uplink sounding reference signal resource for uplink beam management.

According to a variation of the procedure shown in Figure 5, the configuration of said uplink reference signal resource for uplink beam management may be a configuration of said uplink reference signal resource for uplink beam management with antenna switching.

According to a variation of the procedure shown in Figure 5, exemplary additional operations are given, which are inherently independent from each other as such. According to such variation, an exemplary method according to exemplary embodiments of the present invention may comprise an operation of receiving a configuration of a transmission configuration indicator state for a downlink transm ission for which a non-codebook based precoder is generated based on said reference signal transm ission utilizing said at least one spatial filter, the transm ission configuration indicator state being indicative of that said at least one uplink reference signal resource or a resource set including said uplink reference signal resource is to be used as a spatial source for downlink reference signal determ ination of said at least one spatial filter for UE receiver.

According to a variation of the procedure shown in Figure 5, the configuration of said transm ission configuration indicator state for said downlink transm ission m ay be received via radio resource control signaling.

According to a variation of the procedure shown in Figure 5, exem plary additional operations are given, which are inherently independent from each other as such . According to such variation, an exem plary m ethod according to exem plary embodim ents of the present invention m ay com prise an operation of receiving a scheduling of a downlink demodulation reference signal precoded with non-codebook based precoder associated with spatial filter based on transm ission configuration indicator state.

According to a variation of the procedure shown in Figure 5, exem plary additional operations are given, which are inherently independent from each other as such. According to such variation, an exem plary m ethod according to exem plary embodim ents of the present invention m ay com prise an operation of receiving said downlink demodulation reference signal with spatial filter according transm ission configuration indicator state spatial inform ation associated with demodulation reference signal resource.

According to a variation of the procedure shown in Figure 5, the at least one configured uplink reference signal set m ay be configured via radio resource control signaling. According to a variation of the procedure shown in Figure 5, the uplink sounding reference signal resource m ay be at least one of an uplink reference signal resource used for user equipm ent antenna switching or uplink beam m anagem ent, an uplink demodulation reference signal resource, and an uplink phase tracking reference signal resource.

According to a variation of the procedure shown in Figure 5, the downlink transm ission towards said term inal m ay be at least one of a downlink demodulation reference signal associated with a physical downlink shared channel, a downlink demodulation reference signal associated with a physical downlink control channel, a downlink channel state inform ation reference signal associated with channel state inform ation acquisition, a downlink channel state inform ation reference signal associated with channel state inform ation beam m anagem ent, a downlink channel state inform ation reference signal associated with fine frequency and tim e tracking, a downlink phase tracking reference signal, and a downlink demodulation reference signal associated with physical broadcast channel, physical downlink control channel and physical downlink shared channel for rem aining m inim um system inform ation , paging, other system inform ation (OSI ) and other broadcast inform ation delivery.

I n other words, according to exemplary em bodim ents of the present invention , a UE procedure and related signaling for situation is provided when there is no beam correspondence between DL RX and UL TX beams at UE-side or UL TX beam m anagem ent is perform ed to identify UE TX beams and related RS resources for DL CSI acquisition or DL transm ission related to any DL RS, e.g. DMRS or CSI - RS.

Thereby, TCI -state based DL beam based operation at carrier frequencies above 6 GHz is enhanced. The UE procedure according to exem plary em bodim ents of the present invention enables the UE to use UL SRS or any other UL RS based DL CSI acquisition for non-codebook based DL transm issions as well as DL user scheduling. Additionally, according to exemplary embodiments of the present invention, a generic spatial reference rule is provided, which defines any UL RS to be as spatial reference for any DL RS.

Thus, generally, according to exemplary embodiments of the present invention, uplink sounding reference signal (UL SRS) resource used for UE antenna switching or any UL RS (including UL SRS) used for UL beam management is used as spatial reference for spatial filter used to receive a downlink reference signal.

According to exemplary embodiments of the present invention, uplink reference signal (UL RS) resource (e.g. sounding reference signal SRS) used for UE antenna switching and/or used for UL beam management is used as spatial reference for spatial filter used to receive downlink demodulation reference signal (DL DMRS) associated with physical downlink shared channel (PDSCH).

According to exemplary embodiments of the present invention, uplink reference signal (UL RS) resource (e.g. sounding reference signal SRS) used for UE antenna switching and/or used for UL beam management is used as spatial reference for spatial filter used to receive DL DMRS associated with physical downlink control channel (PDCCH).

According to exemplary embodiments of the present invention, uplink reference signal (UL RS) resource (e.g. sounding reference signal SRS) used for UE antenna switching and/or used for UL beam management is used as spatial reference for spatial filter used to receive downlink channel state information reference signal (DL CSI-RS) associated with channel state information (CSI) acquisition.

According to exemplary embodiments of the present invention, uplink reference signal (UL RS) resource (e.g. sounding reference signal SRS) used for UE antenna switching and/or used for UL beam management is used as spatial reference for spatial filter used to receive DL CSI-RS associated with CSI beam management.

According to exemplary embodiments of the present invention, uplink reference signal (UL RS) resource (e.g. sounding reference signal SRS) used for UE antenna switching and/or used for UL beam management is used as spatial reference for spatial filter used to receive DL CSI-RS associated with fine frequency and time tracking (TRS) .

According to exemplary embodiments of the present invention, uplink reference signal (UL RS) resource (e.g. sounding reference signal SRS) used for UE antenna switching and/or used for UL beam management is used as spatial reference for spatial filter used to receive DL phase tracking reference signal (PTRS).

In addition, for further exploitation of uplink reference signal (UL RS) resources as spatial source for downlink reference signal (DL RS) transmission at carrier frequencies above 6GHz, the following UL RS to DL RS spatial reference rules are provided according to exemplary embodiments.

In detail, according to exemplary embodiments of the present invention, UL DMRS resource is used as a spatial reference for spatial filter used to receive DL DMRS associated with PDSCH.

According to exemplary embodiments of the present invention, uplink demodulation reference signal (UL DMRS) resource is used as spatial reference for spatial filter used to receive DL DMRS associated with PDCCH.

According to exemplary embodiments of the present invention, UL DMRS resource is used as spatial reference for spatial filter used to receive DL CSI-RS associated with CSI acquisition. According to exemplary embodiments of the present invention, UL DMRS resource is used as spatial reference for spatial filter used to receive DL CSI-RS associated with CSI beam management.

According to exemplary embodiments of the present invention, UL DMRS resource is used as spatial reference for spatial filter used to receive DL CSI-RS associated with fine frequency and time tracking (TRS) .

According to exemplary embodiments of the present invention, UL DMRS resource is used as spatial reference for spatial filter used to receive DL phase tracking reference signal (PTRS).

According to exemplary embodiments of the present invention, uplink phase tracking reference signal (UL PTRS) resource is used as a spatial reference for spatial filter used to receive DL DMRS of PDSCH.

According to exemplary embodiments of the present invention, UL PTRS resource is used as a spatial reference for spatial filter used to receive DL DMRS Of PDCCH.

According to exemplary embodiments of the present invention, UL PTRS resource is used as spatial reference for spatial filter used to receive DL CSI-RS associated with CSI acquisition.

According to exemplary embodiments of the present invention, UL PTRS resource is used as spatial reference for spatial filter used to receive DL CSI-RS associated with CSI beam management.

According to exemplary embodiments of the present invention, UL PTRS resource is used as spatial reference for spatial filter used to receive DL CSI-RS associated with fine frequency and time tracking (TRS). According to exemplary embodiments of the present invention, UL PTRS resource is used as spatial reference for spatial filter used to receive DL phase tracking reference signal (PTRS).

Finally, according to exemplary embodiments of the present invention, UL PTRS resource is used as spatial reference for spatial filter used to receive DL a downlink demodulation reference signal associated with a physical broadcast channel, PDCCH and PDSCH for remaining minimum system information RMSI, paging, other system information OSI and other broadcast information delivery.

In more specific terms, according to exemplary embodiments of the present invention, a network is enabled to configure UL RS, e.g. SRS/D MRS/ PTRS, to be used as a spatial source in TCI-state for DL RS, e.g. DMRS of PDSCH/PDCCH or CSI-RS (CSI acquisition, beam management, or time and frequency tracking, DMRS for a physical broadcast channel, PDCCH and PDSCH for remaining minimum system information RMSI, paging, other system information OSI and other broadcast information delivery).

As a result of this, when implementing exemplary embodiments of the present invention, NR Rel-15 or Rel-16 would be able to support non codebook based precoding when DL CSI is obtained via on UL SRS based sounding and beam correspondence is not supported at UE-side or UL RS (e.g. UL SRS) based beam management with and without beam correspondence support at UE-side.

Figure 8 shows an implementation example of exemplary embodiments of the present invention in conjunction of UL SRS based beam management and antenna switching as well as DL DMRS transmission. In particular, Figure 8 shows an example of the enhancement to TCI-state that enables UL SRS to be used as a spatial QCL source (QCL-type D) for DL DMRS configuration. Here, the resource configuration for SRS resource sets associated with UL BM and antenna switching are exactly sam e as in Figure 7. Furthermore, the antenna switching works sim ilarly as previously described in Figure 6 and Figure 7. I n com parison with previous exam ple in Figure 7, by using exemplary embodim ents of the present invention a network is able to configure UL SRS resources, i.e. SRS resource 1 and SRS resource 2, to be used as a spatial source in TCI -state for DMRS of PDSCH before DL DMRS is scheduled.

This is indicated in the Figure 8 by the two solid lines (arrows) passing from the lower left area of Figure 8 to the upper right area of Figure 8. Based on this inform ation, UE is able to direct its RX spatial filter (beam form er) correctly according to DL TX beam associated with DMRS of PDSCH.

Consequently, by utilizing exem plary em bodim ents of the present invention , the non-codebook based precoding can also be used in NR Rel- 1 5/ 1 6 system , thereby solving at least in part problems of the prior art.

A definition of the TCI -state including a reference to the above-explained resources to be used as a spatial source for spatial filter according to exemplary embodim ents of the present invention is presented below. ASN1 START

- TAG- TCI -STATE- START

TCI -State : := SEQUENCE {

tci-Stateld TCI-Stateld,

qd- Type l QCL-lnfo,

qcl- Type2 QCL-lnfo OPTIONAL

}

QCL-lnfo : : = SEQUENCE {

referenceSignal CHOICE {

csi-rs NZP- CSI - RS- ResourceConfigl d, ssb SSB- Id,

-- A TRS (Tracking Reference Signal) configuration represented as a set of CSI-RS- Resources in a NZP-CSI-ResourceSetld

trs NZP-CSI-ResourceSetld srs SRS- Resource! d

} ,

q cl - Type ENUMERATED { typeA, typeB, typeC, typeD} ,

Here, the line reflecting the necessary reference to the resources to be used as a spatial reference for spatial filter is:

srs SRS- Resource! d

This line m ay be inserted into a corresponding TCI -state definition e.g. in TS 38.331 .

Concluding, according to exem plary em bodim ents of the present invention, a UE may be configured with RS for UL. I n particular, according to exemplary embodim ents of the present invention, a UE m ay be configured with SRS for UL sounding with antenna switching. Further, according to exemplary embodim ents of the present invention, a UE m ay be configured with SRS for UL beam m anagem ent without antenna switching.

Further, according to exem plary em bodim ents of the present invention, the UE m ay perform SRS transm ission with the corresponding spatial filter(s) . Further, according to exemplary embodiments of the present invention, the UE may be configured with TCI state which links in terms of QCL type D the DL DMRS with the UL SRS.

Finally, according to exemplary embodiments of the present invention, the UE may receive DL DMRS which is associated with the spatial filter used for the transmission of the SRS.

Further concluding, according to exemplary embodiments of the present invention, a gNB may configure by RRC-signaling SRS set(s) with resources for antenna switching.

Further, according to exemplary embodiments of the present invention, the gNB may configure by RRC-signaling TCI state associated with DMRS of PDSCH such that UL SRS resource(s) is used as spatial source, i.e. QCL- type D, for DMRS of PDSCH.

Further, according to exemplary embodiments of the present invention, based on UL SRS based DL CSI, the gNB may compute non-codebook based precoder to be used with DMRS of PDSCH and PDSCH.

Finally, according to exemplary embodiments of the present invention, the gNB may schedule DL DMRS and PDSCH transmissions via PDCCH

Consequently, according to exemplary embodiments of the present invention, TCI-state based DL beam based operation at carrier frequencies above 6 GHz is enhanced.

Further, according to exemplary embodiments of the present invention, NR Rel-15 is enabled to support non-codebook based precoding in DL when beam correspondence is not supported at UE-side. However, the NR Rel-15 is enabled to support non-codebook based precoding in DL not only in such case. In particular, it is enabled as well for example when beam correspondence is supported at UE-side. In other words, the present invention provides benefit as well with beam correspondence with UL SRS or any other UL RS beam management.

The above-described procedures and functions may be implemented by respective functional elements, processors, or the like, as described below.

In the foregoing exemplary description of the network entity, only the units that are relevant for understanding the principles of the invention have been described using functional blocks. The network entity may comprise further units that are necessary for its respective operation. However, a description of these units is omitted in this specification. The arrangement of the functional blocks of the devices is not construed to limit the invention, and the functions may be performed by one block or further split into sub-blocks.

When in the foregoing description it is stated that the apparatus, i.e. network entity (or some other means) is configured to perform some function, this is to be construed to be equivalent to a description stating that a (i.e. at least one) processor or corresponding circuitry, potentially in cooperation with computer program code stored in the memory of the respective apparatus, is configured to cause the apparatus to perform at least the thus mentioned function. Also, such function is to be construed to be equivalently implementable by specifically configured circuitry or means for performing the respective function (i.e. the expression “unit configured to" is construed to be equivalent to an expression such as“means for”).

In Figure 9, an alternative illustration of apparatuses according to exemplary embodiments of the present invention is depicted. As indicated in Figure 9, according to exemplary embodiments of the present invention, the apparatus (network node) 10’ (corresponding to the network node 10) comprises a processor 91, a memory 92 and an interface 93, which are connected by a bus 94 or the like. Further, according to exemplary embodiments of the present invention, the apparatus (terminal) 30’ (corresponding to the terminal 30) comprises a processor 95, a memory 96 and an interface 97, which are connected by a bus 98 or the like, and the apparatuses may be connected via link 99, respectively.

The processor 91/95 and/or the interface 93/97 may also include a modem or the like to facilitate communication over a (hardwire or wireless) link, respectively. The interface 93/97 may include a suitable transceiver coupled to one or more antennas or communication means for (hardwire or wireless) communications with the linked or connected device(s), respectively. The interface 93/97 is generally configured to communicate with at least one other apparatus, i.e. the interface thereof.

The memory 92/96 may store respective programs assumed to include program instructions or computer program code that, when executed by the respective processor, enables the respective electronic device or apparatus to operate in accordance with the exemplary embodiments of the present invention.

In general terms, the respective devices/ apparatuses (and/or parts thereof) may represent means for performing respective operations and/or exhibiting respective functionalities, and/or the respective devices (and/or parts thereof) may have functions for performing respective operations and/or exhibiting respective functionalities.

When in the subsequent description it is stated that the processor (or some other means) is configured to perform some function, this is to be construed to be equivalent to a description stating that at least one processor, potentially in cooperation with computer program code stored in the memory of the respective apparatus, is configured to cause the apparatus to perform at least the thus mentioned function. Also, such function is to be construed to be equivalently implementable by specifically configured means for performing the respective function (i.e. the expression“processor configured to [cause the apparatus to] perform xxx-ing” is construed to be equivalent to an expression such as“means for xxx-ing”).

According to exemplary embodiments of the present invention, an apparatus representing the network node 10 comprises at least one processor 91, at least one memory 92 including computer program code, and at least one interface 93 configured for communication with at least another apparatus. The processor (i.e. the at least one processor 91, with the at least one memory 92 and the computer program code) is configured to perform configuring at least one uplink reference signal set with uplink resources for beam management (thus the apparatus comprising corresponding means for configuring), to perform configuring a terminal with an uplink reference signal resource for uplink beam management out of said at least one uplink reference signal set, to perform receiving, from said terminal, an uplink reference signal transmission utilizing at least one spatial filter corresponding to said uplink reference signal resource for uplink beam management (thus the apparatus comprising corresponding means for receiving), and to perform generating a non-codebook based precoder for downlink transmission towards said terminal based on said received uplink reference signal transmission utilizing said at least one spatial filter (thus the apparatus comprising corresponding means for generating).

Further, according to exemplary embodiments of the present invention, an apparatus representing the terminal 30 comprises at least one processor 95, at least one memory 96 including computer program code, and at least one interface 97 configured for communication with at least another apparatus. The processor (i.e. the at least one processor 95, with the at least one memory 96 and the computer program code) is configured to perform receiving a configuration of an uplink reference signal resource for uplink beam management out of at least one configured uplink reference signal set (thus the apparatus comprising corresponding means for receiving), and to perform transmitting, to a network node, an uplink reference signal transmission utilizing at least one spatial filter corresponding to said uplink reference signal resource for uplink beam management (thus the apparatus comprising corresponding means for transmitting).

For further details regarding the operability/functionality of the individual apparatuses, reference is made to the above description in connection with any one of Figures 1 to 8, respectively.

For the purpose of the present invention as described herein above, it should be noted that

- method steps likely to be implemented as software code portions and being run using a processor at a network server or network entity (as examples of devices, apparatuses and/or modules thereof, or as examples of entities including apparatuses and/or modules therefore), are software code independent and can be specified using any known or future developed programming language as long as the functionality defined by the method steps is preserved;

- generally, any method step is suitable to be implemented as software or by hardware without changing the idea of the embodiments and its modification in terms of the functionality implemented;

- method steps and/or devices, units or means likely to be implemented as hardware components at the above-defined apparatuses, or any module(s) thereof, (e.g., devices carrying out the functions of the apparatuses according to the embodiments as described above) are hardware independent and can be implemented using any known or future developed hardware technology or any hybrids of these, such as MOS (Metal Oxide Semiconductor), CMOS (Complementary MOS), BiMOS (Bipolar MOS), BiCMOS (Bipolar CMOS), ECL (Emitter Coupled Logic), TTL (Transistor- Transistor Logic), etc., using for example ASIC (Application Specific IC (Integrated Circuit)) components, FPGA (Field-programmable Gate Arrays) components, CPLD (Complex Programmable Logic Device) components or DSP (Digital Signal Processor) components; - devices, units or means (e.g. the above-defined network entity or network register, or any one of their respective units/means) can be implemented as individual devices, units or means, but this does not exclude that they are implemented in a distributed fashion throughout the system, as long as the functionality of the device, unit or means is preserved;

- an apparatus like the user equipment and the network entity /network register may be represented by a semiconductor chip, a chipset, or a (hardware) module comprising such chip or chipset; this, however, does not exclude the possibility that a functionality of an apparatus or module, instead of being hardware implemented, be implemented as software in a (software) module such as a computer program or a computer program product comprising executable software code portions for execution/being run on a processor;

- a device may be regarded as an apparatus or as an assembly of more than one apparatus, whether functionally in cooperation with each other or functionally independently of each other but in a same device housing, for example.

In general, it is to be noted that respective functional blocks or elements according to above-described aspects can be implemented by any known means, either in hardware and/or software, respectively, if it is only adapted to perform the described functions of the respective parts. The mentioned method steps can be realized in individual functional blocks or by individual devices, or one or more of the method steps can be realized in a single functional block or by a single device.

Generally, any method step is suitable to be implemented as software or by hardware without changing the idea of the present invention. Devices and means can be implemented as individual devices, but this does not exclude that they are implemented in a distributed fashion throughout the system, as long as the functionality of the device is preserved. Such and similar principles are to be considered as known to a skilled person. Software in the sense of the present description com prises software code as such com prising code m eans or portions or a com puter program or a com puter program product for perform ing the respective functions, as well as software (or a com puter program or a com puter program product) em bodied on a tangible medium such as a com puter- readable (storage) m edium having stored thereon a respective data structure or code m eans/portions or em bodied in a signal or in a chip, potentially during processing thereof .

The present invention also covers any conceivable com bination of m ethod steps and operations described above, and any conceivable combination of nodes, apparatuses, modules or elem ents described above, as long as the above-described concepts of m ethodology and structural arrangem ent are applicable.

I n view of the above, there are provided m easures for channel state inform ation reciprocity support for beam based operation. Such m easures exemplarily com prise configuring at least one uplink reference signal set with uplink resources for beam m anagem ent, configuring a term inal with an uplink reference signal resource for uplink beam m anagem ent out of said at least one uplink reference signal set , receiving, from said term inal, an uplink reference signal transm ission utilizing at least one spatial filter corresponding to said uplink reference signal resource for uplink beam m anagem ent, and generating a non-codebook based precoder for downlink transm ission towards said term inal based on said received uplink reference signal transm ission utilizing said at least one spatial filter.

Even though the invention is described above with reference to the exam ples according to the accom panying drawings, it is to be understood that the invention is not restricted thereto. Rather, it is apparent to those skilled in the art that the present invention can be modified in m any ways without departing from the scope of the inventive idea as disclosed herein. List of acronyms and abbreviations

3GPP Third Generation Partnership Project

BM beam management

CSI-RS channel state information reference signal CRI CSI-RS resource indicator

DL downlink

DMRS demodulation reference signal

PDSCH physical downlink shared channel

PTRS phase tracking reference signal

OSI other system information

QCL quasi-co-location

RMSI remaining system information

RSRP reference signal received power

SRS sounding reference signal

TCI transmission configuration indicator TRS time frequency tracking reference signal UL uplink

Claims

1 . A m ethod com prising

configuring at least one uplink reference signal set with uplink resources for beam m anagem ent,

configuring a term inal with an uplink reference signal resource for uplink beam m anagem ent out of said at least one uplink reference signal set,

receiving, from said term inal, an uplink reference signal transm ission utilizing at least one spatial filter corresponding to said uplink reference signal resource for uplink beam m anagem ent, and

generating a non-codebook based precoder for downlink transm ission towards said term inal based on said received uplink reference signal transm ission utilizing said at least one spatial filter.

2. The m ethod according to claim 1 , wherein

said at least one uplink reference signal set with uplink resources for beam m anagem ent is at least one uplink sounding reference signal set with uplink resources for beam m anagem ent, and/or

said at least one uplink reference signal set with uplink resources for beam m anagem ent is at least one uplink reference signal set with uplink resources for beam m anagem ent with antenna switching.

3. The m ethod according to claim 1 or 2, further com prising

configuring a transm ission configuration indicator state for said downlink transm ission towards said term inal indicative of that said at least one uplink reference signal resource or a resource set including said uplink reference signal resource is to be used as a spatial source for downlink reference signal resource determ ination of said at least one spatial filter.

4. The m ethod according to claim 3, wherein said configuring said transm ission configuration indicator state for said downlink transm ission towards said term inal utilizes radio resource control signaling.

5. The m ethod according to any of claims 1 to 4, further com prising

scheduling a downlink demodulation reference signal associated with said at least one spatial filter based on said non-codebook based precoder.

6. The m ethod according to claim 5, further com prising

transm itting said downlink demodulation reference signal to said term inal.

7. The m ethod according to any of claims 1 to 6, wherein

said configuring said at least one uplink reference signal set utilizes radio resource control signaling.

8. The m ethod according to any of claims 1 to 7, wherein

said uplink reference signal resource is at least one of

an uplink sounding reference signal resource used for user equipm ent antenna switching or uplink beam m anagem ent,

an uplink demodulation reference signal resource, and an uplink phase tracking reference signal resource.

9. The m ethod according to any of claims 1 to 8, wherein

said downlink transm ission towards said term inal is at least one of a downlink demodulation reference signal associated with a physical downlink shared channel,

a downlink demodulation reference signal associated with a physical downlink control channel,

a downlink channel state inform ation reference signal associated with channel state inform ation acquisition,

a downlink channel state inform ation reference signal associated with channel state inform ation beam m anagem ent, a downlink channel state inform ation reference signal associated with fine frequency and tim e tracking,

a downlink phase tracking reference signal, and

a downlink demodulation reference signal associated with physical broadcast channel, physical downlink control channel and physical downlink shared channel for rem aining m inim um system inform ation, paging, other system inform ation (OSI ) and other broadcast inform ation delivery.

1 0. A m ethod com prising

receiving a configuration of an uplink reference signal resource for uplink beam m anagem ent out of at least one configured uplink reference signal set, and

transm itting, to a network node, an uplink reference signal transm ission utilizing at least one spatial filter corresponding to said uplink reference signal resource for uplink beam managem ent.

1 1 . The m ethod according to claim 1 0, wherein

said configuration of said uplink reference signal resource for uplink beam m anagem ent is a configuration of an uplink sounding reference signal resource for uplink beam m anagem ent, and/or

said configuration of said uplink reference signal resource for uplink beam m anagem ent is a configuration of said uplink reference signal resource for uplink beam m anagem ent with antenna switching.

12. The m ethod according to claim 1 0 or 1 1 , further com prising

receiving a configuration of a transm ission configuration indicator state for a downlink transm ission for which a non-codebook based precoder is generated based on said reference signal transm ission utilizing said at least one spatial filter, the transm ission configuration indicator state being indicative of that said at least one uplink reference signal resource or a resource set including said uplink reference signal resource is to be used as a spatial source for downlink reference signal determ ination of said at least one spatial filter.

13. The m ethod according to claim 12, wherein

said configuration of said transm ission configuration indicator state for said downlink transm ission is received via radio resource control signaling.

14. The m ethod according to claim 12 or 13, further com prising

receiving a scheduling of a downlink demodulation reference signal precoded with non-codebook based precoder associated with spatial filter based on transm ission configuration indicator state.

1 5. The m ethod according to claim 14, further com prising

receiving said downlink demodulation reference signal with spatial filter according transm ission configuration indicator state spatial inform ation associated with demodulation reference signal resource.

1 6. The m ethod according to any of claims 1 0 to 1 5, wherein

said at least one configured uplink reference signal set is configured via radio resource control signaling.

1 7. The m ethod according to any of claims 1 0 to 1 6, wherein

said uplink sounding reference signal resource is at least one of

an uplink reference signal resource used for user equipm ent antenna switching or uplink beam m anagem ent,

1 8. The m ethod according to any of claims 1 2 to 1 7, wherein

said downlink transm ission towards said term inal is at least one of a downlink demodulation reference signal associated with a physical downlink shared channel, a downlink demodulation reference signal associated with a physical downlink control channel,

a downlink channel state inform ation reference signal associated with channel state inform ation beam m anagem ent,

a downlink channel state inform ation reference signal associated with fine frequency and tim e tracking,

a downlink phase tracking reference signal, and

1 9. An apparatus, the apparatus com prising

at least one processor,

at least one m emory including com puter program code, and at least one interface configured for com m unication with at least another apparatus,

the at least one processor, with the at least one memory and the computer program code, being configured to cause the apparatus to perform :

receiving, from said term inal, an uplink reference signal transm ission utilizing at least one spatial filter corresponding to said uplink reference signal resource for uplink beam m anagem ent , and generating a non-codebook based precoder for downlink transm ission towards said term inal based on said received uplink reference signal transm ission utilizing said at least one spatial filter.

20. The apparatus according to claim 1 9, wherein

21 . The apparatus according to claim 1 9 or 20, wherein

22. The apparatus according to claim 21 , wherein

said configuring said transm ission configuration indicator state for said downlink transm ission towards said term inal utilizes radio resource control signaling.

23. The apparatus according to any of claims 1 9 to 22, wherein

24. The apparatus according to claim 23, wherein

transm itting said downlink demodulation reference signal to said term inal.

25. The apparatus according to any of claims 1 9 to 24, wherein

26. The apparatus according to any of claims 1 9 to 25, wherein

said uplink reference signal resource is at least one of

27. The apparatus according to any of claims 1 9 to 26, wherein

a downlink phase tracking reference signal, and a downlink demodulation reference signal associated with physical broadcast channel, physical downlink control channel and physical downlink shared channel for rem aining m inim um system inform ation, paging, other system inform ation (OSI ) and other broadcast inform ation delivery.

28. An apparatus, the apparatus com prising

at least one processor,

29. The apparatus according to claim 28, wherein

30. The apparatus according to claim 28 or 29, wherein

the at least one processor, with the at least one memory and the computer program code, being configured to cause the apparatus to perform : receiving a configuration of a transm ission configuration indicator state for a downlink transm ission for which a non-codebook based precoder is generated based on said reference signal transm ission utilizing said at least one spatial filter, the transm ission configuration indicator state being indicative of that said at least one uplink reference signal resource or a resource set including said uplink reference signal resource is to be used as a spatial source for downlink reference signal determ ination of said at least one spatial filter.

31 . The apparatus according to claim 30, wherein

32. The apparatus according to claim 30 or 31 , wherein

33. The apparatus according to claim 32, wherein

34. The apparatus according to any of claims 28 to 33, wherein

35. The apparatus according to any of claims 28 to 34, wherein

said uplink sounding reference signal resource is at least one of

36. The apparatus according to any of claims 30 to 35, wherein

a downlink phase tracking reference signal, and

37. An apparatus, the apparatus com prising

control circuitry configured to

configure at least one uplink reference signal set with uplink resources for beam m anagem ent, and to configure a term inal with an uplink reference signal resource for uplink beam m anagem ent out of said at least one uplink reference signal set,

receiving circuitry configured to receive, from said term inal, an uplink reference signal transm ission utilizing at least one spatial filter corresponding to said uplink reference signal resource for uplink beam m anagem ent, and

generating circuitry configured to generate a non-codebook based precoder for downlink transm ission towards said term inal based on said received uplink reference signal transm ission utilizing said at least one spatial filter.

38. An apparatus, the apparatus com prising

receiving circuitry configured to receive a configuration of an uplink reference signal resource for uplink beam m anagem ent out of at least one configured uplink reference signal set, and

transm itting circuitry configured to transm it, to a network node, an uplink reference signal transm ission utilizing at least one spatial filter corresponding to said uplink reference signal resource for uplink beam m anagem ent.

39. A com puter program product com prising com puter-executable com puter program code which, when the program is run on a computer, is configured to cause the com puter to carry out the m ethod according to any one of claims 1 to 9, or 1 0 to 1 8.

40. The com puter program product according to claim 39, wherein the com puter program product com prises a com puter- readable m edium on which the com puter-executable computer program code is stored, and/or wherein the program is directly loadable into an internal m emory of the com puter or a processor thereof.