Methods, devices, and computer programs in relation to uplink transmission

Abstract

According to the present disclosure, there are provided a devices and methods for transmitting, to a network entity, coherency information indicative of coherency between the device's transmit antenna ports of a transmit antenna group, the reference signal coherency information including a coherency assumption and corresponding coherency antenna port group information.

Description

[0001] TITLEMETHODS, DEVICES, AND COMPUTER PROGRAMS IN RELATION TO UPLINKTRANSMISSION TECHNICAL FIELD Various example embodiments of this disclosure relate to one or more methods,devices and / or computer programs relating to data transmission with increasednumber of antenna elements and ports. BACKGROUNDTo address an uplink / downlink coverage issue for new frequency bands (e.g.,6.425-7.125 GHz and 7-24 GHz), the use of larger antenna arrays with increased number of antenna elements and ports at transmission and reception side are required. The use of large antenna arrays can enable enhanced coverage andspectrum efficiency in both uplink and downlink. However, increased number ofantenna elements and ports lead to more complex channels and can for examplelead to additional problems like difficulties for decoding a received signal. Thus,this disclosure aims at improving uplink and / or downlink data transmission withincreased number of antenna elements and ports. SUMMARY Various example embodiments of this disclosure aim at addressing at least part of the issue and / or problems and drawbacks either explicitly described herein or otherwise apparent to a person skilled in the relevant art(s) to provide methods, devices, computer programs, and / or systems by which, in particular but notexclusively, UL coverage can be improved.Various example embodiments will be described with respect to certain aspects. These aspects are not intended to indicate key or essential features of the various example embodiments, nor are they intended to be used to otherwise limit the scope of this disclosure. Other features, aspects and elements of the various example embodiments will be readily apparent to a person skilled in the art in view of the disclosure. According to the present disclosure, there is provided a device, comprising meansfor transmitting, to a network entity, coherency information indicative of acoherency between the device’s transmit antenna ports of a transmit antennagroup, the coherency information including a coherency assumption andcorresponding coherency antenna port group information.Further, according to the present disclosure, there is likewise provided a method,comprising transmitting, to a network entity, coherency information indicative ofcoherency between a terminal device’s transmit antenna ports of a transmitantenna group, the coherency information including a coherency assumption andcorresponding coherency antenna port group information.The coherency information according to the present disclosure may further includea coherency time period indicating for how long the coherency assumption can bemaintained.According to a first aspect, there is provided a device (100; 100’), comprising:transmission means for transmitting, from a terminal device, reference signal coherency information indicative of coherency between the terminal device’s transmit antenna ports of a transmit antenna group to a network entity, the reference signal coherency information including a coherency assumption andcorresponding coherency antenna port group information, and receiving meansfor, in response to transmitting the reference signal coherency information, receiving an indication of an uplink reference signal configuration from the networkentity, wherein the transmission means is further configured for transmitting areference signal according to the received indication of the uplink reference signal configuration via an uplink channel to the network entity.According to an example aspect, the reference signal coherency informationfurther includes a coherency time period indicating for how long the coherency assumption can be maintained.According to an example aspect, the coherency assumption includes informationabout a coherency capability in at least one of an amplitude domain and a phasedomain.According to an example aspect, the coherency antenna port group informationincludes a number of antenna ports to be used for simultaneous transmission and fulfilling the coherency assumption included in the reference signal coherency information.According to an example aspect, the reference signal coherency informationfurther includes a number of coherency antenna port groups used for transmission.According to an example aspect, the reference signal coherency informationfurther includes an indication of a supported reference signal type.According to an example aspect, the reference signal coherency informationfurther includes capability information about a maximum number of symboldifference accepted by the device for uplink reference signal transmission.According to an example aspect, the transmission means is further configured fortransmitting, to the network entity, a plurality of reference signal coherency information elements, each reference signal coherency information element representing reference signal coherency information for one or more transmit antenna port groups out of a plurality of transmit antenna port groups, thereceiving means is configured for receiving a plurality of indications of uplinkreference signal configurations, each reference signal configuration correspondingto one reference signal coherency information element, and the transmissionmeans is further configured for transmitting a plurality of reference signals according to the received indications of the uplink reference signal configurations via one or more uplink channels to the network entity.According to an example aspect, the transmission means is further configured fortransmitting, to the network entity, coherency information indicative of a coherency between the device’s transmit antenna ports of a transmit antenna port group configured for a second uplink channel, the receiving means is furtherconfigured for receiving from the network entity a precoding scheme, the devicecomprises a processing means configured for encoding data based on the receivedprecoding scheme, and the transmission means is further configured fortransmitting, to the network entity via the second uplink channel, the data encodedbased on the received precoding scheme.According to a second aspect, there is provided a method, comprising:transmitting, from a terminal device, reference signal coherency information indicative of coherency between the terminal device’s transmit antenna ports of a transmit antenna group to a network entity, the reference signal coherency information including a coherency assumption and corresponding coherencyantenna port group information, in response to transmitting the reference signalcoherency information, receiving an indication of an uplink reference signalconfiguration from the network entity, and transmitting, to the network entity viaan uplink channel, a reference signal according to the received indication of the uplink reference signal configuration.According to a third aspect, there is provided a device, comprising: receivingmeans for receiving, from a terminal device, reference signal coherency information indicative of coherency between the terminal’s transmit antenna ports of a transmit antenna group, the reference signal coherency information including a coherency assumption and corresponding coherency antenna port groupinformation, processing means for selecting a reference signal configuration foruplink transmission corresponding to the coherency antenna port groupinformation based on the received coherency information, and transmission meansfor transmitting an indication of the reference signal configuration to the terminaldevice, wherein the receiving means is further configured for receiving, from theterminal device via an uplink channel, a reference signal generated based on theselected reference signal configuration, and the processing means is furtherconfigured for estimating channel state information of the uplink channel based on the received reference signal.According to an example aspect, the reference signal coherency informationfurther includes a coherency time period indicating for how long the coherency assumption can be maintained.According to an example aspect, the coherency assumption includes informationabout a coherency capability in at least one of an amplitude domain and a phasedomain.According to an example aspect, the coherency antenna port group informationincludes a number of antenna ports to be used for simultaneous transmission and fulfilling the coherency assumption included in the reference signal coherencyinformation, and the processing means is configured for selecting the referencesignal configuration for uplink transmission further based on the number of antenna ports included in the coherency antenna port group information.According to an example aspect, the reference signal coherency informationfurther includes a number of coherency antenna port groups used for transmission,and the processing means is configured for selecting the reference signalconfiguration for uplink transmission further based on the number of coherency antenna port groups used for transmission.According to an example aspect, the reference signal coherency informationfurther includes an indication of a supported reference signal type, and theprocessing means is configured for selecting the reference signal configuration for uplink transmission further based on the indication of the supported reference signal type.According to an example aspect, the reference signal coherency informationfurther includes capability information about a maximum number of symboldifference accepted by the terminal device for uplink reference signal transmission,and the processing means is configured for selecting the reference signalconfiguration for uplink transmission further based on the maximum number ofsymbol difference accepted for uplink reference signal transmission.According to an example aspect, the receiving means is configured for receiving,from the terminal device, a plurality of reference signal coherency information elements, each reference signal coherency information element representing reference signal coherency information for one or more transmit antenna portgroups out of a plurality of transmit antenna port groups, the processing means isconfigured for selecting a plurality of reference signal configurations for uplink transmission, each reference signal configuration corresponding to the coherency antenna port group information based on the received coherency information ofone received reference signal coherency information element, and transmissionmeans is configured for transmitting the plurality of indications of uplink reference signal configurations to the terminal device, the receiving means is further configured for receiving, from the terminal device via one or more uplink channels, a plurality of reference signals, each generated based on one of the selectedreference signal configurations, and the processing means is further configured forestimating channel state information based on the received plurality of reference signals.According to an example aspect, the receiving means is further configured forreceiving, from the terminal device, coherency information indicative of a coherency between the terminal device’s transmit antenna ports of a transmitantenna port group configured for a second uplink channel, the processing meansis further configured for selecting a suitable precoding scheme based on thereceived coherency information, the transmission means is further configured fortransmitting the selected precoding scheme to the terminal device, the receivingmeans is further configured for receiving, from the terminal device, a second signalvia the second uplink channel, and wherein the processing means is configured fordecoding the second signal based on the selected precoding scheme.According to a fourth aspect, there is provided a method, comprising: receiving,from a terminal device, reference signal coherency information indicative of coherency between the terminal’s transmit antenna ports of a transmit antenna group, the reference signal coherency information including a coherency assumption and corresponding coherency antenna port group information, selecting a reference signal configuration for uplink transmission corresponding to the coherency antenna port group information based on the received coherencyinformation, transmitting an indication of the reference signal configuration to theterminal device, receiving, via an uplink channel from the terminal device, areference signal generated based on the selected reference signal configuration,and estimating channel state information of the uplink channel based on thereceived reference signal.According to a fifth aspect, there is provided a device (100; 100’), comprising: atleast one processor 110, at least one memory 120 including computer programcode and a plurality of antennas 130 configured for communication with at leastanother device, wherein the at least one processor, with the at least one memoryand the computer program code and with the plurality of antennas is configuredto transmit, from a terminal device, reference signal coherency information indicative of coherency between the terminal device’s transmit antenna ports of a transmit antenna group to a network entity, the reference signal coherency information including a coherency assumption and corresponding coherencyantenna port group information, to receive, in response to transmitting thereference signal coherency information, an indication of an uplink reference signal configuration from the network entity, and to transmit a reference signal according to the received indication of the uplink reference signal configuration via an uplink channel to the network entity.According to an example aspect, the reference signal coherency informationfurther includes a coherency time period indicating for how long the coherency assumption can be maintained.According to an example aspect, the coherency assumption includes informationabout a coherency capability in at least one of an amplitude domain and a phasedomain.According to an example aspect, the coherency antenna port group informationincludes a number of antenna ports to be used for simultaneous transmission and fulfilling the coherency assumption included in the reference signal coherency information.According to an example aspect, the reference signal coherency informationfurther includes a number of coherency antenna port groups used for transmission.According to an example aspect, the reference signal coherency informationfurther includes an indication of a supported reference signal type.According to an example aspect, the reference signal coherency informationfurther includes capability information about a maximum number of symboldifference accepted by the device for uplink reference signal transmission.According to an example aspect, the at least one processor, with the at least onememory and the computer program code and with the plurality of antennas isfurther configured to transmit, to the network entity, a plurality of reference signal coherency information elements, each reference signal coherency information element representing reference signal coherency information for one or more transmit antenna port groups out of a plurality of transmit antenna port groups, to receive a plurality of indications of uplink reference signal configurations, each reference signal configuration corresponding to one reference signal coherency information element, and to transmit a plurality of reference signals according to the received indications of the uplink reference signal configurations via one or more uplink channels to the network entity.According to an example aspect, the at least one processor, with the at least onememory and the computer program code and with the plurality of antennas isfurther configured to transmit, to the network entity, coherency information indicative of a coherency between the device’s transmit antenna ports of a transmit antenna port group configured for a second uplink channel, to receive from the network entity a precoding scheme, to encode data based on the receivedprecoding scheme, and to transmit, to the network entity via the second uplinkchannel, the data encoded based on the received precoding scheme.According to a sixth aspect, there is provided a device, comprising: at least oneprocessor 210, at least one memory 220 including computer program code and aplurality of antennas 230 configured for communication with at least anotherdevice, wherein the at least one processor, with the at least one memory and thecomputer program code and with the plurality of antennas is configured to receive,from a terminal device, reference signal coherency information indicative of coherency between the terminal’s transmit antenna ports of a transmit antenna group, the reference signal coherency information including a coherency assumption and corresponding coherency antenna port group information, to select a reference signal configuration for uplink transmission corresponding to the coherency antenna port group information based on the received coherencyinformation, to transmit an indication of the reference signal configuration to theterminal device, to receive, from the terminal device via an uplink channel, a reference signal generated based on the selected reference signal configuration, and to estimate channel state information of the uplink channel based on the received reference signal.According to an example aspect, the reference signal coherency informationfurther includes a coherency time period indicating for how long the coherency assumption can be maintained.According to an example aspect, the coherency assumption includes informationabout a coherency capability in at least one of an amplitude domain and a phasedomain.According to an example aspect, the coherency antenna port group informationincludes a number of antenna ports to be used for simultaneous transmission and fulfilling the coherency assumption included in the reference signal coherency information, and the processing means is configured for selecting the reference signal configuration for uplink transmission further based on the number of antenna ports included in the coherency antenna port group information.According to an example aspect, the reference signal coherency informationfurther includes a number of coherency antenna port groups used for transmission,and the processing means is configured for selecting the reference signal configuration for uplink transmission further based on the number of coherency antenna port groups used for transmission.According to an example aspect, the reference signal coherency informationfurther includes an indication of a supported reference signal type, and the processing means is configured for selecting the reference signal configuration for uplink transmission further based on the indication of the supported reference signal type.According to an example aspect, the reference signal coherency informationfurther includes capability information about a maximum number of symboldifference accepted by the terminal device for uplink reference signal transmission,and the processing means is configured for selecting the reference signalconfiguration for uplink transmission further based on the maximum number ofsymbol difference accepted for uplink reference signal transmission.According to an example aspect, the at least one processor, with the at least onememory and the computer program code and with the plurality of antennas isfurther configured to receive, from the terminal device, a plurality of reference signal coherency information elements, each reference signal coherency information element representing reference signal coherency information for one or more transmit antenna port groups out of a plurality of transmit antenna port groups, to select a plurality of reference signal configurations for uplink transmission, each reference signal configuration corresponding to the coherency antenna port group information based on the received coherency information of one received reference signal coherency information element, to transmit the plurality of indications of uplink reference signal configurations to the terminal device, to receive, from the terminal device via one or more uplink channels, a plurality of reference signals, each generated based on one of the selected reference signal configurations, and to estimate channel state information based on the received plurality of reference signals.According to an example aspect, the at least one processor, with the at least onememory and the computer program code and with the plurality of antennas isfurther configured to receive, from the terminal device, coherency information indicative of a coherency between the terminal device’s transmit antenna ports of a transmit antenna port group configured for a second uplink channel, to select a suitable precoding scheme based on the received coherency information, to transmit the selected precoding scheme to the terminal device, to receive, fromthe terminal device, a second signal via the second uplink channel, and to decodethe second signal based on the selected precoding scheme.According to a seventh aspect, there is provided a computer program comprisinginstructions, which when executed by a device, cause the device to perform oneof the methods described above.According to an eighth aspect, there is provided a non-transitory computer-readable medium comprising program instructions that, when executed by adevice, cause the device to perform one of the methods described above.By virtue of at least some of the above aspects, one or more of the following advantages can be obtained:- efficient uplink transmission using multiple (a high number, i.e. more than8 like e.g. 12, 16, 24, or even more) uplink antenna ports -a terminal device can utilize different antenna arrangements with differentUL reference signal resources based on different transmit coherencyassumptions; -a network access entity like a gNB (6G-gNB) can properly configure an ULreference signal configuration for a high number of antenna ports for ULreference signal transmission without violating the terminal device’scapability in terms of coherency between transmit antenna ports;- the network access entity can get an understanding about how long in timea terminal device can maintain transmit coherency between multipleantenna ports of an antenna group in terms of phase and / or amplitude intime domain; -the network access entity can properly select and configure a referencesignal configuration; -comb offset values and cyclic shift values of a reference signal configurationcan be combined appropriately; -the network access entity can (more) accurately estimate channel stateinformation (CSI) based on the reference signal selected according to refsignal coherency information;- the network access entity can provide a precoding scheme that is suitablefor a certain channel based on the estimated channel state information(CSI); and- it is possible to efficiently leverage a high number of antenna ports (e.g.more than 8 antenna ports) for uplink transmission in general andparticularly for uplink reference signal transmission.BRIEF DESCRIPTION OF THE DRAWINGS For a proper understanding of example embodiments, reference is made to the accompanying drawings, wherein: Fig. 1 illustrates signaling in relation to an example embodiment;Fig. 2 (a) illustrates an example for implementing a terminal device such asa UE according to at least some example embodiments of this disclosure; Fig. 2 (b) illustrates an alternative example for implementing a terminaldevice such as a UE according to at least some example embodiments of this disclosure; and Fig. 3 (a) illustrates an example for implementing a network access entitysuch as a gNB or a 6G-gNB according to at least some example embodiments ofthis disclosure; Fig. 3 (b) illustrates an alternative example for implementing a networkaccess entity such as a gNB or a 6G-gNB according to at least some exampleembodiments of this disclosure; Fig. 4 illustrates four antennas and corresponding antenna port configurations; and Fig. 5 illustrates four antennas and other corresponding antenna port configurations. DETAILED DESCRIPTION Herein below, certain example embodiments are described in detail with reference to the accompanying drawings, wherein at least some features of example embodiments can be freely combined with features of other embodiments, unless described otherwise. However, it is to be understood that the description of certain embodiments is given by way of example only, and that it is by no way intended to be understood as limiting aspects of embodiments to the disclosed details. Various example embodiments are described with respect to uplink reference signal transmission. However, it is to be understood that this disclosure is not limited thereto and can also be applied to various other transmission modes and / or channels.Moreover, it is to be understood that a device is configured to perform acorresponding method, and a respective method can be executed by acorrespondingly configured device although in some cases, only the device or onlythe method may be described. Known specifications support up to 24 antenna ports for demodulation referencesignals (DMRS) and up to 8 antenna ports for uplink (UL) sounding reference signal(SRS) resources with different usages, such as e.g. codebook and antenna-switching. However, such limited number of antenna ports may prevent efficient utilization of larger antenna arrays for coverage and spectral efficient enhancement purposes at a UE. Higher peak data rate for UL could play a significant role in short-range applications such as home entertainment, video surveillance / monitoring in industrial / healthcare / safety, integrated access and backhaul (IAB), and otherapplications where devices power / form-factor / costs are not as stringent as intraditional handheld devices. The use of larger antenna arrays, in terms of physical antenna elements and logical antenna ports, can be used to enable enhanced uplink coverage and spectralefficiency with new and existing frequency bands. For example, UL transmissionwith more than 8 transmit antenna ports (>8Tx) can be used to bridge the gapbetween downlink (DL) and UL spectral efficiency, especially with customerpremise equipment (CPE) / fixed wireless access (FWA) / vehicle / industrialdevices. To efficiently leverage high number of antenna ports (>8Tx) for uplink referencesignal transmission, a network entity or a network access entity like e.g. a nextgeneration node B, a gNB or a 6G-gNB and a terminal device such as a userequipment (UE) should have a common understanding about the terminal device’scapabilities in terms of transmit coherency associated with UL transmission and inparticular for UL transmission of reference signals such as e.g. sounding referencesignal (SRS). New radio (NR) does so far not provide support for a SRS resourcelevel Coherency. Rather, NR provides PUSCH Coherency capability indication isonly available when assuming same coherency capability for all UL SRS resourcesapplied for PUSCH transmission. In other words, currently available specificationsdo not allow the terminal device to utilize different antenna arrangements fordifferent UL reference signal resources based on different coherency assumptions.If the network entity and the terminal device do not have common understandingabout the terminal device’s transmit phase coherency assumption(s), an ambiguityproblem arises between the terminal device and the network entity related to whatkind of UL reference signal resource configurations the terminal device can use tosupport a higher number of UL reference signal antenna ports (e.g. 16 antennaports or even higher). However, no solutions therefore have been published orknown. An example for reference signals is a sounding reference signal (SRS), which is briefly described in the following. However, it is to be understood that SRS is justan example, and any various other reference signals may be employed in thecontext of the present disclosure. Other examples for reference signals aredemodulation reference signals (DMRS) and phase tracking reference signals (PTRS). For example, a reference signal can be configured as a sounding reference signal (SRS) as follows.An SRS resource may be configured by an SRS-Resource IE or an SRS-PosResource IE and may for example be emitted via- ^ap SRS ∈ {1, 2, 4, 8} or more (e.g. 12, 16, 24, 32) antenna ports {^^} ^=0^apSRS−1, where the number of antenna ports can be given by a higher layerparameter nrofSRS-Ports, if nrofSRS-Ports is configured, or otherwise:- ^ap SRS = 1, and ^^ = 1000 + ^ when the SRS resource is in a SRS resource setwith a higher-layer parameter usage in SRS-ResourceSet not set to'nonCodebook', or determined according to TS 38.214 when the SRS resource isin a SRS resource set with higher-layer parameter usage in SRS-ResourceSet set to 'nonCodebook'.^symbSRS ∈ {1, 2, 4, 8, 10, 12, 14} consecutive OFDM symbols are given by afield nrofSymbols contained in the higher layer parameter resourceMapping.The starting position ^0 in the time domain can be given by ^0=^symbslot – 1 − ^offset ,where the offset ^offset ∈ {0,1,…,13} counts symbols backwards from the end ofthe slot and can be given by the field startPosition contained in the higher layerparameter resourceMapping and ^offset ≥ ^symbSRS−1.Furthermore, ^0 is the frequency-domain starting position of the soundingreference signal.The cyclic shift ^^ for antenna port ^^ is given as where ^SRScs ∈{0, 1, …, ^SRScs,max−1} is contained in the higher layer parametertransmissionComb. Examples for the maximum number of cyclic shifts ^SRScs,maxare given by Table 1 below.The quantities ^^̅ and ^̅apSRS are given by- if the higher-layer parameter nrofSRS-Ports-n8 equals ports8tdm - otherwise Table 1: Maximum number of cyclic shifts ^SRS cs,max as a function of ^TC. The frequency-domain starting position ^0(^^) is defined by

[0002] Furthermore, antenna number configuration aspects may be listed as follows.The following SRS parameters can be semi-statically configurable by higher layer parameter SRS-Resource or SRS-PosResource.An srs-ResourceId or SRS-PosResourceId can be used to determine an SRSresource configuration identity.A Number of SRS ports can be defined by the higher layer parameter nrofSRS-Ports and described in clause 6.4.1.4 of TS 38.211. If the number of ports is notdefined or configured, nrofSRS-Ports can be assumed to be 1. Support of time division mapping subsets of ports of the SRS resource into Ssymbols (e.g. S=2) can be defined by the higher layer parameter [tdm], wherethe SRS ports are evenly distributed in two symbols. This applies for example whenthe SRS resource set is configured with a higher layer parameter usage in SRS- ResourceSet set to ‘codebook’, or ‘antennaSwitching’, and nrofSRS-Ports is set to ‘n8’. A Comb offset hopping pattern with repetition can be defined by the higher layer parameter [combOffsetHoppingWithRepetition], where the parameter can be setto e.g. ‘[per-symbol]’ or ‘[per-R-repetition]’, subject to the terminal device’s (UE’s)capability. When the parameter is set to ‘[per-symbol]’, the comb offset hopping pattern is determined by the symbol index, and the comb offset hopping pattern is determined by the symbol index of the first symbol of the repetition when the parameter is set to ‘[per-R-repetition]’.A Cyclic shift can be defined by the higher layer parameter cyclicShift-n2,cyclicShift-n4, or cyclicShift-n8 for transmission comb value of e.g. 2, 4 or 8, etc.When cyclic shift hopping is configured by the higher layer parameter [cyclicShiftHopping] for an SRS resource in an SRS resource set with the usageconfigured as 'antennaSwitching', subject to the terminal device’s capabilities, thecyclic shift can be updated at every symbol. For the cyclic shift hopping, a terminaldevice can be configured with a subset of cyclic shifts by the higher layerparameter [cyclicShiftHoppingSubset], where the cyclic shift hopping is performedonly across the cyclic shifts configured in the subset. The terminal device is notexpecting that the cyclic shift hopping and the higher layer parameter [tdm] are configured simultaneously. Conventionally, an Uplink reference signal is configured without taking into accountcoherency information about transmit antenna ports and / or transmit antenna portgroups.According to an example embodiment of this disclosure, a terminal device such asa UE transmits coherency information about transmit antenna ports and / ortransmit antenna port groups to a network access entity like e.g. a gNB or a 6G-gNB. This allows to efficiently leverage high number of antenna ports (e.g. morethan 8) for uplink transmission and in particular uplink reference signaltransmission, in that the network access entity and the terminal device can havea common understanding about the terminal device’s capabilities in terms oftransmit coherency associated with transmit antenna ports used e.g. for emittingUL reference signals, as well as for transmitting arbitrary other signals.In this regard, it is assumed that the terminal device comprises multiple transmitantennas which may be grouped into antenna groups. In the context of thisdisclosure, antenna ports typically represent a logical concept rather than physicalports, and antenna ports may be mapped to or associated with antennas basedbeam forming, i.e. based on which antenna(s) form a beam transmitting a signalof a certain antenna port. A plurality of antenna ports may be grouped into antennaport groups.For example, in Fig. 4, an antenna panel comprising 4 antennas 1 to 4 is illustratedon the left. Assuming that each antenna forms one beam, each antenna is associated with one antenna port. For example, antenna port a is associated with antenna 1, antenna port b is associated with antenna 2, antenna port c is associated with antenna 3 and antenna port d is associated with antenna 4. In Fig. 4, it is also assumed that all four antenna ports a, b, c and d form one antenna port group. Depending on which antenna port is configured to be switched on for data transmission, different antenna port group configurations are possible. For example in the table on the right of Fig. 4, it is illustrated for which antenna portconfiguration, which antenna ports are used. In antenna port group configuration4, all four antenna ports are assumed to transmit data. Thus, correspondingtransmit coherency information would refer to coherency between all four antennaports a, b, c and d. In exemplary antenna groups 5, 6, 7 and 8, respectively threeantenna ports are assumed to transmit. Thus, corresponding transmit coherencyinformation would refer to coherency between the respective three antenna portsused for transmission. In Fig. 5, the same antennas as in Fig. 4 are illustrated and an association of antenna ports with antennas is also assumed to be the same as with respect to Fig. 4. However, in Fig. 5, it is assumed that the four antennas are divided into two separate antenna port groups. That is, in the example of Fig. 5, antenna ports a and b are grouped to antenna port group A, whereas antenna ports c and d are grouped into antenna port group B.In such a case, each antenna port group may transmit signals via a differentchannel, e.g. a control channel and a data channel, or two parallel channels of the same type.Furthermore, in this case, for each antenna port group, respective coherencyinformation applying to the antenna group only can be determined and transmittedto a network entity. That is, for instance, antenna ports a and b (thus antennagroup A) can simultaneously transmit a signal with coherent phase (that is, withcoherency capability in phase domain) while antenna ports c and d (thus antennagroup B) can simultaneously transmit a signal with coherent amplitude (that is,with coherency capability in amplitude domain).In the following, an example embodiment is described, in which coherencyinformation relates to coherency between multiple antenna ports thatsimultaneously transmit a signal. More specifically, according to this exampleembodiment, the terminal device like a UE indicates transmit coherencyinformation associated with coherency between transmit antenna ports belongingto the same transmit antenna port group. Antenna port groups can be associatedwith logical antenna ports, which are in turn associated with physical antennaelements or antenna panels including multiple antenna elements. For example, thetransmit coherency information can include at least one of the followinginformation elements, which are described in more detail afterwards:• ‘full-Phase-Coherency’ assumption• ‘full-Amplitude-Coherency’ assumption• ‘full-PhaseAndAmplitude-Coherency’ assumption• ‘partial-PhaseAndAmplitude-Coherency’ assumption• ‘partial-Phase-Coherency’ assumption^ ‘partial-Amplitude-Coherency’ assumption• time units (e.g. symbols / slots),• reference signal type,• set of transmit antenna port groups,• maximum phase rotation, e.g. in degrees or radians, and• maximum amplitude deviation, e.g. in decibel (dB).In this regard, the ‘full-Phase-Coherency’ assumption and the ‘partial-Phase-Coherency’ assumption are examples for coherency information in the phasedomain, the ‘full-Amplitude-Coherency’ assumption and the ‘partial-Amplitude-Coherency’ assumption are examples for coherency information in the amplitudedomain, and the ‘full-PhaseAndAmplitude-Coherency’ assumption and the ‘partial-PhaseAndAmplitude-Coherency’ assumption are examples for a combination ofamplitude and phase coherency assumptions, i.e. examples for information abouta coherency capability in the amplitude domain and in the phase domain.That is, the terminal device indicates phase and / or amplitude coherencyassumption per transmit antenna group (or antenna panel being a componentincluding multiple antennas) defining coherency of associated antenna ports interms of phase and / or amplitude (phase and amplitude coherency information isassumed to obtained via capability signaling). In other words, the coherency information can define coherency of all logicalantenna ports of the plurality of logical antenna ports in phase domain, orthe coherency information can define coherency of all logical antenna portsof the plurality of logical antenna ports in amplitude domain, orthe coherency information can define coherency of all logical antenna portsof the plurality of logical antenna ports in phase and amplitude domain, orthe coherency information can define coherency of a subset of logicalantenna ports of the plurality of logical antenna ports in phase domain, orthe coherency information can define coherency of the subset of logicalantenna ports of the plurality of logical antenna ports in amplitude domain, orthe coherency information can define coherency of the subset of logicalantenna ports of the plurality of logical antenna ports in phase and amplitudedomain.Based on this indicated coherency capability information, the network access entitylike a (6G) gNB can for example properly configure an UL reference signal resourceconfiguration (or a resource configuration in general) for a high number (e.g. aplurality like more than 8) of antenna ports by taking into account the terminaldevice’s uplink transmit coherency capabilities, to enable UL reference signalresource transmission without violating the terminal device’s transmit coherencycapability. For example, configuring an UL reference signal resource configurationcan also be performed by selecting a previously stored UL reference signal resourceconfiguration.For example, the resource configuration may define at least one soundingreference signal resource associated with a plurality of logical antenna ports (of anantenna port group) that are assignable to physical antenna elements of anantenna array (and / or of an antenna group). The sounding reference signalresource may be defined by combinations of comb offset values and cyclic shiftvalues, each combination of the combinations of comb offset values and cyclic shiftvalues corresponding to one antenna port of the plurality of antenna ports. In thisregard, for example, a first antenna port may correspond to a first combination ofa first comb offset value and a first cyclic shift value of the combinations of comboffset values and cyclic shift values, a second antenna port may correspond to asecond combination of a second comb offset value and a second cyclic shift valueof the combinations of comb offset values and cyclic shift values, and the firstcomb offset value and the second comb offset value may be the same or differentfrom each other.In at least some example embodiments, the terminal device shall maintain thereported transmit coherency capability while transmitting one or more ULreference signal resources configured based on the coherency information.Signaling of an example embodiment relating to a UE as the terminal device andgNB or 6G-gNB as the network access entity is illustrated in Figure 1. It is to benoted that in the context of this disclosure, referring to a gNB also encompasses a6G-gNB, or any other (radio) access node of similar functionality.In step S101, the UE 100 transmits coherency information, such as referencesignal coherency information to the gNB 200. Such reference signal coherencyinformation is indicative of coherency between the terminal device’s transmitantenna ports of a transmit antenna group to be used in uplink transmission, e.g.when transmitting a reference signal.According to at least some example embodiments, the coherency information(reference signal coherency information) includes a coherency assumption andcorresponding coherency antenna port group information. The coherencyassumption can be any of a ‘full-Phase-Coherency’ assumption, a ‘full-Amplitude-Coherency’ assumption, a ‘full-PhaseAndAmplitude-Coherency’ assumption, a‘partial-PhaseAndAmplitude-Coherency’ assumption, a ‘partial-Phase-Coherency’assumption, or a ‘partial-Amplitude-Coherency’ assumption.According to at least some example embodiments, the coherency information orthe reference signal coherency information may further include a coherency timeperiod indicating for how long the coherency assumption can be maintained.Respective coherency assumptions and corresponding data may be stored at theterminal device, associated with corresponding antenna port configurations. Thatis, for each possible antenna port configuration of an antenna group, correspondingcoherency information may be stored. Hence, based on selected antenna groupsand their antenna configuration to be used, the terminal device can read thecorresponding coherency assumptions from a storage means included in theterminal device. Alternatively or in addition thereto, it is also conceivable thatrespective coherency assumptions may be provided by another entity, i.e. some third party.The coherency time period indicates a time period for how long the transmitantenna ports of a respective transmit antenna port group can simultaneously transmit in coherency, that is within respective deviations indicated by thecoherency assumptions (e.g. less than a maximum amplitude deviation, e.g. 1 or2 dB amplitude deviation and / or less than a maximum phase rotation of e.g. 5 or10 degree or e.g. pi / 4 radians, within which the terminal device can maintaintransmit phase coherency for an antenna port group, or any other suitable valuesindicated via the coherency assumption). Such coherency time period may beindicated by indicating a number of symbols or slots with default numerology (like for example sub-carrier spacing), e.g. 15kHz or 30KHz).According to at least some example embodiments, the coherency antenna portgroup information may further include a number of antenna ports included in anantenna port group. That is, the coherency antenna port group informationincludes information about how many transmission antenna ports are to be used simultaneously, i.e. in parallel.In step S102, after receiving the reference signal coherency information from theUE 100, the gNB 200 selects or configures a configuration for uplink transmission.In this example, the gNB 200 selects a reference signal configuration to be usedby the UE for uplink transmission of e.g. a reference signal from the UE 100, i.e.to be emitted by the antenna port group corresponding to the coherency antennaport group information based on the received coherency information. Nonetheless,it is to be understood that the configuration for uplink transmission can also relate to other uplink channels such as e.g. a Physical Uplink Control Channel (PUCCH)or a Physical Uplink Shared Channel (PUSCH) and is not limited to referencesignals.When the gNB 200 selects a reference signal configuration, like e.g. a UL SRSresource, the gNB 200 may group a certain coherency capability of antenna portsfor transmitting reference signals via the antenna ports of an antenna port group.For example, certain reference signals might be more suitable than others when the transmission antenna ports can maintain phase coherency, whereas for casein which the transmission antenna ports can maintain amplitude coherency but notphase coherency, the suitable reference signals might be different referencesignals than for a case of phase coherency. That is, respective reference signalscan be grouped by their suitability for channel state information estimationdepending on required coherency between employed transmit antenna ports.Since the gNB 200 as the network entity knows exactly about UL SRS resourceIDs, it can later determine which of the resources are transmitted e.g. in a fully-phase-coherent manner or in a fully-amplitude coherent manner, or even both, ina fully-phase-coherent and fully-amplitude coherent manner.Afterwards, in step S103, the gNB 200 transmits an indication of the referencesignal configuration to the UE 100. Such indication of the reference signalconfiguration can for example be an SRS-ResourceId or an SRS-PosResourceId,which the UE 100 can use to determine an SRS resource configuration identity ofa known sounding reference signal (SRS), of which both the UE and the gNB areaware. In response to receiving such indication of the reference signal configuration, the UE 100 emits (in step S104a) a corresponding reference signal and thus transmits a reference signal according to the received indication of the uplink reference signal configuration to the gNB 200 in step S104b.Based on the received reference signal, the gNB 200 then estimates the channelstate information in step S105. Since the gNB 200 as the network access entityknows exactly about UL SRS resource IDs, it can determine which of the resourcesare transmitted e.g. in a ‘fully-phase-coherent’ manner or in a ‘fully-amplitude-coherent’ manner.Given that the reference signal was selected and / or configured based on thereference signal coherency information, the UE 100 can accurately transmit theselected reference signal enabling an accurate estimation of the channel stateinformation at the gNB 200.Afterwards, any arbitrary uplink channels can be efficiently employed, using thechannel state information estimated in step S105 for decoding at the gNB 200.In the following, various coherency assumptions are described, which may betransmitted in the coherency information. That is, by including any of theexemplary coherency assumptions described below, the terminal device can clearlyindicate or report what coherency the terminal device’s antenna ports can fulfill forcertain channels and / or transmission port quantities used for uplink transmission.A ‘full-Phase-Coherency’ assumption indicates that associated antenna ports withinthe resource, i.e. all antenna ports of a specific transmit antenna port group fullyfulfill a phase coherency assumption. That is, the respective antenna ports canmaintain coherent phase (e.g. within 5 or 10 degrees) while simultaneouslytransmitting an uplink signal like e.g. a reference signal. In the case of the ‘full-Phase-Coherency’ assumption, amplitude coherency is not assumed.A ‘full-Amplitude-Coherency’ assumption indicates that associated antenna portswithin the resource, i.e. all antenna ports of a specific transmit antenna port groupfulfill an amplitude coherency assumption. That is, the respective antenna portscan maintain coherent amplitude (e.g. within 1 or 2 dB) while simultaneouslytransmitting an uplink signal like e.g. a reference signal. In the case of the ‘full-Amplitude-Coherency’ assumption, phase coherency is not assumed.A ‘full-PhaseAndAmplitude-Coherency’ assumption indicates that associatedantenna ports within the resource, i.e. all antenna ports of a specific transmitantenna port group fulfill both amplitude and phase coherency assumption. Thatis, the respective antenna ports can maintain both coherent amplitude andcoherent phase while simultaneously transmitting an uplink signal like e.g. a reference signal.Such ‘full-Phase-Coherency’ assumption, ‘full-Amplitude-Coherency’ assumption,and ‘full-PhaseAndAmplitude-Coherency’ assumption may also apply to multipleantenna port groups at the same time or also for antenna ports of different antenna port groups if multiple antenna port groups are indicated in the coherency information.A ‘partial-Phase-Coherency’ assumption indicates that one or more groups ofantenna ports associated within the resource, i.e. all antenna ports within specifictransmit antenna port groups fully fulfill a phase coherency assumption (i.e.amplitude coherency is not assumed), where phase coherency between differentantenna port groups not assumed.A ‘partial-Amplitude-Coherency’ assumption indicates that one or more groups ofantenna ports associated within the resource, i.e. all antenna ports within specifictransmit antenna port groups fully fulfill an amplitude coherency assumption (butphase coherency is not assumed). However, the amplitude coherency betweendifferent antenna groups is not assumed.A ‘partial-PhaseAndAmplitude-Coherency’ assumption indicates that one or moregroups of antenna ports associated within the resource, i.e. all antenna portswithin a specific transmit antenna port group fully fulfill both a phase coherencyassumption and an amplitude coherency assumption. However, both phase andamplitude coherency between different antenna groups is not assumed.Alternatively, the terminal device may also transmit a ‘None-Coherency’assumption. The ‘None-Coherency’ assumption indicates that the antenna portsassociated within the resource, i.e. the antenna ports of a specific transmit antennaport group do not fully fulfill both of phase and amplitude coherency assumption.That is, the ‘None-Coherency’ assumption indicates that none of the above-described coherency assumptions is applicable for a specific antenna port group.According to at least some example embodiments, the terminal device cantransmit a plurality of coherency information elements including e.g. referencesignal coherency information, each coherency information element representingcoherency information for one or more transmit antenna port groups out of aplurality of available transmit antenna port groups. That is, the terminal device may have a plurality of transmit antenna port groupsand each coherency information element may represent reference signalcoherency information for one (a specific) transmit antenna port group out of aplurality of transmit antenna port groups. According to at least some example embodiments, the terminal device maytransmit multiple coherency information elements for different antenna portgroups. In such case, the network access entity may select multiple signal orchannel configurations like e.g. reference signal configurations for uplinktransmission corresponding to the respective coherency information elementsbased on the received coherency information. That is, the network access entitymay select a specific reference signal configuration or channel configuration foreach transmit antenna port group, for which respective coherency information isreceived at the network access entity.For example, the network entity may configure a sounding reference signalresource by defining combinations of comb offset values and cyclic shift values,each combination of the combinations of comb offset values and cyclic shift valuescorresponding to one antenna port of the plurality of antenna ports.Alternatively or in addition, different reference signal coherency informationelements can also be reference signal type specific. That is, different referencesignal coherency information elements can include different indicated referencesignal type as supported by a specific antenna port group for uplink transmission.Additionally or alternatively, different reference signal coherency informationelements can differ by being related to different sets of transmit antenna groups.In at least some example embodiments, in addition or as an alternative totransmitting reference signal coherency information, the terminal device maytransmit, to the network access entity, coherency information indicative ofcoherency between the terminal device’s transmit antenna ports of a transmitantenna group for another (a second) uplink channel, like e.g. a Physical UplinkControl Channel (PUCCH) or a Physical Uplink Shared Channel (PUSCH).Thus, when the network access entity receives a second signal via the seconduplink channel, it can decode the second signal using the coherency informationindicative of the coherency between the terminal device’s transmit antenna portsof the transmit antenna port group configured for the second uplink channel.For example, for improved decoding based on the received coherency information,the network entity may select a suitable precoding scheme (e.g. a codebook)based on the received coherency information (e.g. based on the number ofantennas to be simultaneously used for transmission and / or correspondingcoherency assumptions).According to at least some example embodiments, the terminal device additionallyreports, that is, transmits capability information about a maximum number ofsymbol difference accepted for signal transmission like e.g. uplink reference signaltransmission for fulfilling indicated coherency assumptions. The maximum numberof symbol difference may for example be number of symbols different to eachother included in a signal. Such maximum number of symbol difference can berelated to single reference signal transmission or to transmission of a set of reference signals.According to at least some example embodiments, the terminal device may applythe reported maximum phase rotation and / or the reported maximum amplitudedeviation information included in the coherency assumptions while determininguplink transmission of uplink reference signal resources (e.g. UL SRS) and / or datachannel (e.g. PUSCH) and / or control channel resources (e.g. PUCCH).According to at least some example embodiments, the terminal device mayindicate uplink transmission phase coherency capability information (e.g. via RRCsignaling) by sending for example the following reference signal coherencyinformation.That is, a transmit phase coherency capability information (or coherencyinformation in general) can comprise at least one of the following informationelements: oa time unit as coherency time period (e.g. a number of symbols or slotswith default numerology (like for example sub-carrier spacing), e.g.15kHz or 30KHz) indicating how long the terminal device can maintainits transmit phase coherency for a certain antenna port group;^ For example, this can be reported in quantized form with N-bits,e.g. N=2, ‘00’ = 8 slots, ‘01’ = 16 slots, ‘10’ = 24 slots, ‘11’ = 32 slots, or any other quantization; oa supported UL reference signal type, e.g. UL SRS;o a number of transmit antenna port groups, for which the coherencyassumption applies, where each transmit antenna port group can beassociated with a set of different antenna arrangements (or antennapanels); oa maximum phase rotation, e.g. 5 or 10 in degree or in radians (e.g.pi / 4), within which the terminal device can maintain transmit phasecoherency for an antenna port group. This can be reported in aquantized form with K-bits. ^In an alternative implementation, it is possible that there is apredefined set of maximum phase rotation values in a RAN1 and / or RAN4 specification out which the supported value is reported. For example, a bit vector with length of Z, definesdifferent possible phase rotation values, e.g. Z=2, where the following example association is defined: ^MSB - 0 of the 4bit-vector is associated with 5degree / radians, and ^MSB -1 of 4bit-vector is associated with 10 degree / radiansAccording to at least some example embodiments, the terminal device mayindicate uplink transmission amplitude coherency capability information (e.g. viaRadio Resource Control (RRC) signaling) by sending for example the followingreference signal coherency information.That is, a transmit amplitude coherency capability information (or coherencyinformation in general) can comprise at least one of the following informationelements:o a time unit as coherency time period (e.g. a number of symbols or slotswith default numerology (like for example sub-carrier spacing), e.g. 15kHz or 30 kHz) indicating how long the terminal device can maintain itstransmit amplitude coherency for a certain antenna port group;^ For example, this can be reported in quantized form with N-bits,e.g. N=2, ‘00’ = 8 slots, ‘01’ = 16 slots, ‘10’ = 24 slots, ‘11’ = 32 slots, or any other quantization; oa supported UL reference signal type, e.g. UL SRS;o a number of transmit antenna port groups, for which the coherencyassumption applies, where each transmit antenna port group can beassociated with a set of different antenna arrangements (or antennapanels); oa maximum amplitude deviation, e.g. 1 or 2 dB, within which theterminal device can maintain transmit coherency for an antenna portgroup. This can be reported in quantized form with M-bits. ^In an alternative implementation, it is possible that there is apredefined set of maximum amplitude deviation values in aRAN1 and / or RAN4 specification out which the supported value is reported. For example, bit vector with length of Q, defines different possible amplitude deviation values, e.g. Q=2, wherethe following example association is defined: ^MSB -0 of the 2bit-vector is associated with 2 dB^ MSB -1 of 2bit-vector is associated with 4 dBAccording to at least some example embodiments, the terminal device mayindicate uplink transmission amplitude and phase coherency capability information(e.g. via RRC signaling) by sending for example the following reference signalcoherency information.That is, a transmit phase and amplitude coherency capability information (orcoherency information in general) can comprise at least one of the followinginformation elements:a time unit as coherency time period (e.g. a number of symbols or slotswith default numerology (like for example sub-carrier spacing), e.g.15kHz or 30KHz) indicating how long the terminal device can maintainits transmit phase and amplitude coherency for a certain antenna portgroup; ^For example, this can be reported in quantized form with N-bits,e.g. N=2, ‘00’ = 8 slots, ‘01’ = 16 slots, ‘10’ = 24 slots, ‘11’ = 32 slots, or any other quantization;a supported UL reference signal type, e.g. UL SRS;a number of transmit antenna port groups, for which the coherencyassumption applies, where each transmit antenna port group can beassociated with a set of different antenna arrangements (or antennapanels);a maximum phase rotation, e.g. 5 or 10 in degree or in radians (e.g.pi / 4), within which the terminal device can maintain transmit phasecoherency for an antenna port group. This can be reported in aquantized form with K-bits. ^In an alternative implementation, it is possible that there is apredefined set of maximum phase rotation values in a RAN1 and / or RAN4 specification out which the supported value is reported. For example, a bit vector with length of Z, definesdifferent possible phase rotation values, e.g. Z=2, where the following example association is defined: ^MSB - 0 of the 4bit-vector is associated with 5degree / radians, and ^MSB -1 of 4bit-vector is associated with 10 degree / radiansa maximum amplitude deviation, e.g. 1 or 2 dB, within which theterminal device can maintain transmit coherency for an antenna portgroup. This can be reported in quantized form with M-bits. ^In an alternative implementation, it is possible that there is apredefined set of maximum amplitude deviation values in aRAN1 and / or RAN4 specification out which the supported value is reported. For example, bit vector with length of Q, definesdifferent possible amplitude deviation values, e.g. Q=2, wherethe following example association is defined: ^MSB -0 of the 2bit-vector is associated with 2 dB^ MSB -1 of 2bit-vector is associated with 4 dBSuch transmit phase and amplitude coherency capability information is an examplefor coherency information, when a ‘full-PhaseAndAmplitude-Coherency’assumption or a ‘partial-PhaseAndAmplitude-Coherency’ assumption is applicable.That is, the full-PhaseAndAmplitude-Coherency’ assumption and the ‘partial-PhaseAndAmplitude-Coherency’ assumption include information about a transmitphase coherency capability and about an amplitude coherency capability, that is,information about a coherency capability in the amplitude domain and in the phasedomain combined. By transmitting from the terminal device, e.g. a UE, transmission coherencyinformation, the network access entity like a gNB also gets an understanding abouthow long in time the UE or terminal device can maintain transmission coherencyin terms of phase and / or amplitude in time domain.Based on this capability information, the network entity can properly configuresuch reference signal configuration (e.g. UL SRS) for uplink transmission, whichprovide accurate UL (e.g. using codebook) and / or DL (e.g. using antenna-switching) channel state information (CSI) estimates, as well as precoding scheme(e.g. proper codebook type) based on the CSI estimates.Any features of the above-described procedures and functions may be implemented by respective functional elements, processors, or the like, as described below. 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 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 device, is configured to causethe device to perform at least the thus mentioned function. Also, such function isto be construed to be equivalently implementable by specifically configured meansfor performing the respective function (e.g., the expression “processor configuredto [cause the device to] perform xxx-ing” is construed to be equivalent to anexpression such as “means for xxx-ing”). Alternatively, such function is to be construed to be equivalently implementable by units specifically configured to perform the respective function (e.g., the expression “processor configured to[cause the device to] perform xxx-ing” is construed to be equivalent to anexpression such as “xxx unit configured to xxx”). In Fig.2, two examples, one in each of Figs.2a and 2b, for implementing a terminaldevice like a UE 100, 100’ according to at least some example embodiments ofthis disclosure are illustrated.According to at least some example embodiments, a device representing theterminal device or UE 100, 100’ comprises as illustrated in Fig. 2a, at least oneprocessor 110, at least one memory 120 and a plurality of antennas 130 configuredfor communication with at least another device. The processor (e.g., the at leastone processor 110, with the at least one memory 120 and the computer programcode and with the plurality of antennas 130) is configured for transmitting, from aterminal device, reference signal coherency information indicative of coherencybetween the terminal device’s transmit antenna ports of a transmit antenna groupto a network entity, the reference signal coherency information including acoherency assumption and corresponding coherency antenna port groupinformation (thus, the device comprises corresponding transmission means fortransmitting, from a terminal device, reference signal coherency informationindicative of coherency between the terminal device’s transmit antenna ports of atransmit antenna group to a network entity, the reference signal coherencyinformation including a coherency assumption and corresponding coherencyantenna port group information), receiving, in response to transmitting thereference signal coherency information, an indication of an uplink reference signalconfiguration from the network entity (thus, the device comprises correspondingreceiving means for receiving, in response to transmitting the reference signalcoherency information, an indication of an uplink reference signal configurationfrom the network entity), and transmitting a reference signal according to thereceived indication of the uplink reference signal configuration (thus, thecorresponding transmission means is further configured for transmitting areference signal according to the received indication of the uplink reference signal configuration). Alternatively, according to at least some example embodiments of this disclosure, as illustrated in Fig. 2b, a device representing the terminal device or UE 100’comprises transmission means 160 for transmitting, from the terminal device,reference signal coherency information indicative of coherency between theterminal device’s transmit antenna ports of a transmit antenna group to a networkentity, the reference signal coherency information including a coherencyassumption and corresponding coherency antenna port group information, andreceiving means 150 for, in response to transmitting the reference signalcoherency information, receiving an indication of an uplink reference signalconfiguration from the network entity, wherein the transmission means 160 are further configured for transmitting a reference signal according to the received indication of the uplink reference signal configuration. Additionally, the terminal device may comprise a processing means 170, e.g. for encoding data based on a received precoding scheme and / or for generating a signal to be transmitted by the transmission means. In Fig.3, two examples, one in each of Figs.3a and 3b, for implementing a network entity such as a (6G-)gNB 200, 200’ according to at least some example embodiments of this disclosure are illustrated.According to at least some example embodiments, a device representing thenetwork entity such as a (6G-)gNB 200, 200’ comprises as illustrated in Fig. 3a, at least one processor 210, at least one memory 220 and a plurality of antennas 230 configured for communication with at least another device. The processor(e.g., the at least one processor 210, with the at least one memory 220 and thecomputer program code and with the plurality of antennas 230) is configured forreceiving, from a terminal device, reference signal coherency informationindicative of coherency between the terminal’s transmit antenna ports of atransmit antenna group, the reference signal coherency information including acoherency assumption and corresponding coherency antenna port groupinformation (thus, the device comprises corresponding receiving means forreceiving, from a terminal device, reference signal coherency informationindicative of coherency between the terminal’s transmit antenna ports of atransmit antenna group, the reference signal coherency information including acoherency assumption and corresponding coherency antenna port groupinformation), selecting a reference signal configuration for uplink transmissioncorresponding to the coherency antenna port group information based on thereceived coherency information (thus, the device comprises correspondingprocessing means for selecting a reference signal configuration for uplinktransmission corresponding to the coherency antenna port group informationbased on the received coherency information), transmitting an indication of thereference signal configuration to the terminal device information (thus, the devicecomprises corresponding transmission means for transmitting an indication of thereference signal configuration to the terminal device information), receiving areference signal generated based on the selected reference signal configuration (thus, the corresponding receiving means is further configured for receiving a reference signal generated based on the selected reference signal configuration),and estimating channel state information based on the received reference signal(thus, the corresponding processing means is further configured for estimatingchannel state information based on the received reference signal). Alternatively, according to at least some example embodiments of this disclosure,as illustrated in Fig. 3b, a device representing the network entity such as a (6G-)gNB 200, 200’ comprises receiving 250 means for receiving, from a terminaldevice 100, reference signal coherency information indicative of coherencybetween the terminal’s transmit antenna ports of a transmit antenna group, thereference signal coherency information including a coherency assumption andcorresponding coherency antenna port group information, processing means 270for selecting a reference signal configuration for uplink transmission correspondingto the coherency antenna port group information based on the received coherencyinformation, and transmission means 260 for transmitting an indication of the reference signal configuration to the terminal device, wherein the receiving means 250 is further configured for receiving, from the terminal device 100 via an uplink channel, a reference signal generated based on the selected reference signal configuration, and the processing means 270 is further configured for estimating channel state information based on the received reference signal. Furthermore, it is to be understood that when it is stated that the processor (or some other means) is configured to perform some function, such function is to be construed to be equivalently implementable by specifically configured circuitry(e.g., the expression “processor configured to [cause the device to] perform xxx-ing” is construed to be equivalent to an expression such as “xxx-circuitry configured to perform xxx-ing”). As used herein, the term “circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and (b) combinations of hardware circuits and software, such as (as applicable): (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (comprising digital signal processor(s)), software, and memory(ies) that work together to cause a device, such as a mobile phone or server, to perform various functions) and (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 utilized for operation. This definition of circuitry applies to all uses of this term herein, comprising in any claims. As a further example, as used herein, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, a cellular network device, or other computing or network device. For the purpose of this disclosure as described herein above, it should be noted that:- method steps may be implemented as software code portions and run using atleast one processor at a network server or network entity (as examples of devices,devices and / or modules thereof, or as examples of entities comprising devicesand / or modules therefore), and may further be implemented as 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 may be implemented as software and / or by hardwarewithout changing the example embodiments and its modification in terms of the functionality implemented; -method steps and / or devices, units or means likely to be implemented ashardware components at the above-defined devices, or any module(s) thereof,(e.g., devices carrying out the functions of the devices according to the exampleembodiments as described herein) 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;- a device like the database or a distributed node, local trainer, etc. may beimplemented by a semiconductor chip, a chipset, or a (hardware) module comprising such chip or chipset; this, however, does not exclude the possibilitythat a functionality of a device 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;- an entity may be regarded as a device or as an assembly of more than one device,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 this disclosure. Devices and means can be implemented as individual devices, but this does not exclude that they also can be implemented in a distributed fashion throughout the system, as long as the functionality of the device is preserved. Software in the sense of this description comprises software code as such comprising code means or portions or a computer program or a computer program product for performing the respective functions, as well as software (or a computerprogram or a computer program product) embodied on a tangible medium, suchas a computer-readable (storage) medium having stored thereon a respective data structure or code means / portions or embodied in a signal or in a chip, potentially during processing thereof. This disclosure also covers any conceivable combination of method steps and operations described above, and any conceivable combination of nodes, devices, modules or elements described above, as long as the above-described concepts of methodology and structural arrangement are applicable. Even though the disclosure is describes various example embodiments with reference to the accompanying drawings, it is to be understood that the disclosure is not restricted thereto. Rather, it is apparent to those skilled in the relevant art(s) that this disclosure can be modified in various ways without departing from the scope of the various example embodiments disclosed herein. According to at least some example embodiments, there may be provided a devicecomprising at least one processor and at least one memory (e.g., non-transitorycomputer readable medium) storing instructions that, when executed by the atleast one processor, cause the device to perform at least any method of thisdisclosure. The term “non-transitory,” as used herein, is a limitation of the medium itself (e.g., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM). According to at least some example embodiments, there may be provided a computer program comprising instructions which, when executed by a device,cause the device to perform at least any method of this disclosure.As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or,” mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements. As used herein, the expression “and / or” also includes any and all combinations of the listed terms, including at least any one of the elements, or at least any two or more of the elements, or at least all of the elements. As used herein, the term “or” refers to a non-exclusive “or” unless otherwise indicated (e.g., use of “or else” or “or in the alternative”). As used herein, unless stated explicitly, performing a respective feature, step, or functionality “in response to A” does not indicate that the respective feature, step, or functionality is performed immediately after “A” occurs as one or more unstatedand intervening features, steps, or functionalities may be performed (at least inpart) between an occurrence of the respective feature, step, or function and “A”. Analogously, performing a respective feature, step, or functionality “based on A” does not indicate that the respective feature, step, or functionality is performed solely based on “A” as the respective feature, step, or functionality may be further based on one or more unstated features, steps, or functionalities in addition to “A”. List of acronyms and abbreviationsCSI Channel State InformationCSI-RS Channel State Information Reference SignaldB DecibelIAB integrated access and backhaulDMRS Demodulation Reference SignalDL Downlink6G-gNB 6G next generation node BgNB next generation node BMCS Modulation and Coding SchemeOFDM orthogonal frequency-division multiplexingPBCH Physical Broadcast ChannelPDCCH Physical Downlink Control ChannelPDSCH Physical Downlink Shared ChannelPTRS Phase Tracking Reference signalPUCCH Physical Uplink Control ChannelPUSCH Physical Uplink Shared ChannelQCL Quasi co-locationRRC Radio Resource ControlSSB Synchronization Signal and PBCH BlockSRS Sounding reference signalTCI Transmission Configuration IndicatorTRS Tracking Reference SignalUE User EquipmentUL Uplink

Claims

CLAIMS1. A device (100; 100’), comprising:transmission means for transmitting, from a terminal device, referencesignal coherency information indicative of coherency between the terminal device’stransmit antenna ports of a transmit antenna group to a network entity, thereference signal coherency information including a coherency assumption andcorresponding coherency antenna port group information, andreceiving means for, in response to transmitting the reference signalcoherency information, receiving an indication of an uplink reference signalconfiguration from the network entity, wherein the transmission means is further configured for transmitting a referencesignal according to the received indication of the uplink reference signalconfiguration via an uplink channel to the network entity.

2. The device according to claim 1, wherein the reference signal coherencyinformation further includes a coherency time period indicating for how long thecoherency assumption can be maintained.

3. The device according to claim 1 or 2, wherein the coherency antenna port groupinformation includes a number of antenna ports to be used for simultaneoustransmission and fulfilling the coherency assumption included in the referencesignal coherency information.

4. The device according to any one of claims 1 to 3, wherein the reference signalcoherency information further includes a number of coherency antenna port groupsused for transmission.

5. The device according to any one of claims 1 to 4, wherein the reference signalcoherency information further includes an indication of a supported referencesignal type.

6. The device according to any one of claims 1 to 5, wherein the reference signalcoherency information further includes capability information about a maximumnumber of symbol difference accepted by the device for uplink reference signaltransmission.

7. The device according to any one of claims 1 to 6, wherein the transmission means is further configured for transmitting, to thenetwork entity, a plurality of reference signal coherency information elements,each reference signal coherency information element representing reference signalcoherency information for one or more transmit antenna port groups out of aplurality of transmit antenna port groups, the receiving means is configured for receiving a plurality of indications ofuplink reference signal configurations, each reference signal configurationcorresponding to one reference signal coherency information element, andthe transmission means is further configured for transmitting a plurality of reference signals according to the received indications of the uplink reference signal configurations via one or more uplink channels to the network entity.

8. The device according to any one of claims 1 to 7, wherein the transmission means is further configured for transmitting, to thenetwork entity, coherency information indicative of a coherency between thedevice’s transmit antenna ports of a transmit antenna port group configured for a second uplink channel, the receiving means is further configured for receiving from the network entity a precoding scheme, the device comprises a processing means configured for encoding data based on the received precoding scheme, and the transmission means is further configured for transmitting, to thenetwork entity via the second uplink channel, the data encoded based on thereceived precoding scheme.

9. A method, comprising:transmitting, from a terminal device, reference signal coherency informationindicative of coherency between the terminal device’s transmit antenna ports of atransmit antenna group to a network entity, the reference signal coherencyinformation including a coherency assumption and corresponding coherencyantenna port group information, in response to transmitting the reference signal coherency information,receiving an indication of an uplink reference signal configuration from the network entity, and transmitting, to the network entity via an uplink channel, a reference signalaccording to the received indication of the uplink reference signal configuration.

10. A device, comprising:receiving means for receiving, from a terminal device, reference signalcoherency information indicative of coherency between the terminal’s transmitantenna ports of a transmit antenna group, the reference signal coherencyinformation including a coherency assumption and corresponding coherencyantenna port group information, processing means for selecting a reference signal configuration for uplinktransmission corresponding to the coherency antenna port group informationbased on the received coherency information, andtransmission means for transmitting an indication of the reference signal configuration to the terminal device, wherein the receiving means is further configured for receiving, from the terminaldevice via an uplink channel, a reference signal generated based on the selectedreference signal configuration, and the processing means is further configured for estimating channel stateinformation of the uplink channel based on the received reference signal.

11. The device according to claim 10, wherein the reference signal coherencyinformation further includes a coherency time period indicating for how long thecoherency assumption can be maintained.

12. The device according to claim 10 or 11, whereinthe coherency antenna port group information includes a number of antennaports to be used for simultaneous transmission and fulfilling the coherencyassumption included in the reference signal coherency information, andthe processing means is configured for selecting the reference signal configuration for uplink transmission further based on the number of antenna portsincluded in the coherency antenna port group information.

13. The device according to any one of claims 10 to 12, wherein the referencesignal coherency information further includes a number of coherency antenna portgroups used for transmission, and the processing means is configured for selecting the reference signal configuration for uplink transmission further based on the number of coherency antenna port groups used for transmission.

14. The device according to any one of claims 10 to 13, wherein the referencesignal coherency information further includes an indication of a supportedreference signal type, and the processing means is configured for selecting the reference signalconfiguration for uplink transmission further based on the indication of thesupported reference signal type.

15. The device according to any one of claims 10 to 14, wherein the referencesignal coherency information further includes capability information about amaximum number of symbol difference accepted by the terminal device for uplinkreference signal transmission, andthe processing means is configured for selecting the reference signalconfiguration for uplink transmission further based on the maximum number ofsymbol difference accepted for uplink reference signal transmission.

16. The device according to any one of claims 10 to 15, wherein the receiving means is configured for receiving, from the terminal device, aplurality of reference signal coherency information elements, each reference signalcoherency information element representing reference signal coherencyinformation for one or more transmit antenna port groups out of a plurality of transmit antenna port groups, the processing means is configured for selecting a plurality of reference signal configurations for uplink transmission, each reference signal configurationcorresponding to the coherency antenna port group information based on thereceived coherency information of one received reference signal coherencyinformation element, and transmission means is configured for transmitting the plurality of indications of uplink reference signal configurations to the terminal device, the receiving means is further configured for receiving, from the terminal device via one or more uplink channels, a plurality of reference signals, each generated based on one of the selected reference signal configurations, and the processing means is further configured for estimating channel state information based on the received plurality of reference signals.

17. The device according to any one of claims 10 to 16, whereinthe receiving means is further configured for receiving, from the terminaldevice, coherency information indicative of a coherency between the terminaldevice’s transmit antenna ports of a transmit antenna port group configured for a second uplink channel, the processing means is further configured for selecting a suitable precodingscheme based on the received coherency information,the transmission means is further configured for transmitting the selected precoding scheme to the terminal device, the receiving means is further configured for receiving, from the terminaldevice, a second signal via the second uplink channel, and whereinthe processing means is configured for decoding the second signal based on the selected precoding scheme.

18. A method, comprising: receiving, from a terminal device, reference signal coherency informationindicative of coherency between the terminal’s transmit antenna ports of atransmit antenna group, the reference signal coherency information including acoherency assumption and corresponding coherency antenna port groupinformation, selecting a reference signal configuration for uplink transmissioncorresponding to the coherency antenna port group information based on thereceived coherency information,transmitting an indication of the reference signal configuration to the terminal device, receiving, via an uplink channel from the terminal device, a reference signalgenerated based on the selected reference signal configuration, and estimating channel state information of the uplink channel based on thereceived reference signal.

19. A computer program comprising instructions, which when executed by adevice, cause the device to perform the method according to claim 9 or 18.

20. A non-transitory computer-readable medium comprising program instructionsthat, when executed by a device, cause the device to perform the methodaccording to claim 9 or 18.

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