Capability indication for channel prediction

Abstract

Disclosed is a method performed by a user equipment, the method comprising: generating a capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation; transmitting the capability indication to a network node; and receiving, from the network node, based on the capability indication, a downlink reference signal configuration to be used for the channel predictor, wherein the downlink reference signal configuration comprises a transmission pattern of a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising at least a first set of resource elements on which the network node intends to transmit the downlink reference signal.

Description

[0001] CAPABILITY INDICATION FOR CHANNEL PREDICTION

[0002] FIELD

[0003] The following example embodiments relate to wireless communication.

[0004] BACKGROUND

[0005] Channel estimation is a process that involves determining the characteristics of a wireless communication channel, such as the path loss, fading, and / or interference. The channel estimate information may be used by the receiver to accurately decode the received data signal.

[0006] SUMMARY

[0007] The scope of protection sought for various example embodiments is set out by the claims. The example embodiments and features, if any, described in this specification that do not fall under the scope of the claims are to be interpreted as examples useful for understanding various embodiments.

[0008] According to a first aspect, there is provided a user equipment comprising: means for generating a capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation; means for transmitting the capability indication to a network node; and means for receiving, from the network node, based on the capability indication, a downlink reference signal configuration to be used for the channel predictor, wherein the downlink reference signal configuration comprises a transmission pattern of a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising at least a first set of resource elements on which the network node intends to transmit the downlink reference signal.

[0009] According to a second aspect, there is provided the user equipment of the first aspect, wherein the transmission pattern further comprises a second set of resource elements on which the network node does not intend to transmit the downlink reference signal, wherein the first set of resource elements is associated with one or more first antenna ports that are equivalent to or different than one or more second antenna ports associated with the second set of resource elements. According to a third aspect, there is provided the user equipment of the second aspect, further comprising: means for receiving, from the network node, the downlink reference signal on the first set of resource elements; means for determining, per antenna port associated with the downlink reference signal, one or more channel estimates associated with the first set of resource elements in at least one of the frequency domain or the time domain; and means for determining, using the channel predictor, per antenna port associated with the downlink reference signal, one or more predicted channel estimates associated with the second set of resource elements in at least one of the frequency domain or the time domain.

[0010] According to a fourth aspect, there is provided the user equipment of the third aspect, further comprising means for demodulating a downlink data channel associated with the downlink reference signal based on a combination of the one or more channel estimates and the one or more predicted channel estimates.

[0011] According to a fifth aspect, there is provided the user equipment of the third or fourth aspect, wherein the downlink reference signal is not received on the second set of resource elements in at least one of the frequency domain or the time domain.

[0012] According to a sixth aspect, there is provided the user equipment of any of the second to fifth aspects, further comprising means for receiving a downlink signal from the network node on at least one resource element of the second set of resource elements in at least one of the frequency domain or the time domain, wherein the downlink signal comprises at least one of: a data signal, a control signal, or another reference signal different from the downlink reference signal for which the downlink reference signal configuration is received.

[0013] According to a seventh aspect, there is provided the user equipment of any of the first to sixth aspects, wherein the channel predictor comprises a machine learning model pretrained based on a set of input data and a set of expected output data, wherein the set of expected output data comprises one or more reference signal channel estimates in at least one of the frequency domain or the time domain per antenna port associated with the downlink reference signal, wherein the set of input data comprises at least one of: a physical resource block level granularity associated with a resource element pattern type of the downlink reference signal in the frequency domain, a symbol position pattern of the downlink reference signal in the time domain, a number of antenna ports associated with the downlink reference signal, a sequence type of the downlink reference signal with one or more initialization seed values, or a downlink precoding technique of the downlink reference signal. According to an eighth aspect, there is provided the user equipment of any of the first to seventh aspects, wherein the downlink reference signal configuration further comprises at least one of: an indication for operating the channel predictor in at least one of the frequency domain or the time domain, or at least one data set identifier from the one or more data set identifiers to be applied for the channel predictor.

[0014] According to a ninth aspect, there is provided the user equipment of any of the first to eighth aspects, wherein the one or more data set identifiers indicate at least one physical resource block density allocation of a reference signal resource element pattern type used for training the channel predictor.

[0015] According to a tenth aspect, there is provided the user equipment of any of the first to eighth aspects, wherein the one or more data set identifiers indicate at least one physical resource block density allocation of a reference signal resource element pattern type that the channel predictor is capable of predicting.

[0016] According to an eleventh aspect, there is provided the user equipment of any of the first to tenth aspects, wherein the one or more data set identifiers indicate at least one reference signal symbol position pattern that the channel predictor is capable of predicting in the time domain.

[0017] According to a twelfth aspect, there is provided the user equipment of any of the first to eleventh aspects, wherein the one or more data set identifiers indicate at least one of: one or more carrier frequencies supported by the channel predictor, one or more numerology options supported by the channel predictor, one or more delay spread ranges supported by the channel predictor, one or more Doppler frequency shift or spread values supported by the channel predictor, one or more user equipment speed values supported by the channel predictor, one or more reference signal sequence initialization seed values supported by the channel predictor, a number of reference signal antenna ports supported by the channel predictor, one or more reference signal resource element types supported by the channel predictor, one or more reference signal sequence types supported by the channel predictor, a physical downlink shared channel allocation length or range, in at least one of the frequency domain or the time domain, supported by the channel predictor, one or more precoding types supported by the channel predictor, or a precoding granularity, in at least one of the frequency domain or the time domain, supported by the channel predictor.

[0018] According to a thirteenth aspect, there is provided the user equipment of any of the first to twelfth aspects, wherein the downlink reference signal comprises one of: a physical downlink shared channel demodulation reference signal, a channel state information reference signal, or a phase-tracking reference signal.

[0019] According to a fourteenth aspect, there is provided a network node comprising: means for receiving, from a user equipment, a capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation; means for determining, based on the capability indication, a downlink reference signal configuration to be used for the channel predictor, wherein the downlink reference signal configuration comprises a transmission pattern for a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising at least a first set of resource elements on which the network node intends to transmit the downlink reference signal; and means for transmitting the downlink reference signal configuration to the user equipment.

[0020] According to a fifteenth aspect, there is provided the network node of the fourteenth aspect, wherein the transmission pattern further comprises a second set of resource elements on which the network node does not intend to transmit the downlink reference signal.

[0021] According to a sixteenth aspect, there is provided the network node of the fifteenth aspect, further comprising: means for transmitting the downlink reference signal to the user equipment on the first set of resource elements; and means for transmitting a downlink signal to the user equipment on at least one resource element of the second set of resource elements in at least one of the frequency domain or the time domain, wherein the downlink signal comprises at least one of: a data signal, a control signal, or another reference signal different from the downlink reference signal for which the downlink reference signal configuration is transmitted.

[0022] According to a seventeenth aspect, there is provided a method performed by a user equipment, the method comprising: generating a capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation; transmitting the capability indication to a network node; and receiving, from the network node, based on the capability indication, a downlink reference signal configuration to be used for the channel predictor, wherein the downlink reference signal configuration comprises a transmission pattern of a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising at least a first set of resource elements on which the network node intends to transmit the downlink reference signal.

[0023] According to an eighteenth aspect, there is provided a method performed by a network node, the method comprising: receiving, from a user equipment, a capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation; determining, based on the capability indication, a downlink reference signal configuration to be used for the channel predictor, wherein the downlink reference signal configuration comprises a transmission pattern for a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising at least a first set of resource elements on which the network node intends to transmit the downlink reference signal; and transmitting the downlink reference signal configuration to the user equipment.

[0024] According to a nineteenth aspect, there is provided a computer program comprising instructions which, when executed by a user equipment, cause the user equipment to perform at least the following: generating a capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation; transmitting the capability indication to a network node; and receiving, from the network node, based on the capability indication, a downlink reference signal configuration to be used for the channel predictor, wherein the downlink reference signal configuration comprises a transmission pattern of a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising at least a first set of resource elements on which the network node intends to transmit the downlink reference signal.

[0025] According to a twentieth aspect, there is provided a computer program comprising instructions which, when executed by a network node, cause the network node to perform at least the following: receiving, from a user equipment, a capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation; determining, based on the capability indication, a downlink reference signal configuration to be used for the channel predictor, wherein the downlink reference signal configuration comprises a transmission pattern for a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising at least a first set of resource elements on which the network node intends to transmit the downlink reference signal; and transmitting the downlink reference signal configuration to the user equipment.

[0026] According to a twenty-first aspect, there is provided a non-transitory computer readable medium comprising program instructions which, when executed by a user equipment, cause the user equipment to perform at least the following: generating a capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation; transmitting the capability indication to a network node; and receiving, from the network node, based on the capability indication, a downlink reference signal configuration to be used for the channel predictor, wherein the downlink reference signal configuration comprises a transmission pattern of a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising at least a first set of resource elements on which the network node intends to transmit the downlink reference signal.

[0027] According to a twenty-second aspect, there is provided a non-transitory computer readable medium comprising program instructions which, when executed by a network node, cause the network node to perform at least the following: receiving, from a user equipment, a capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation; determining, based on the capability indication, a downlink reference signal configuration to be used for the channel predictor, wherein the downlink reference signal configuration comprises a transmission pattern for a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising at least a first set of resource elements on which the network node intends to transmit the downlink reference signal; and transmitting the downlink reference signal configuration to the user equipment. According to a twenty -third aspect, there is provided a computer readable medium comprising program instructions which, when executed by a user equipment, cause the user equipment to perform at least the following: generating a capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation; transmitting the capability indication to a network node; and receiving, from the network node, based on the capability indication, a downlink reference signal configuration to be used for the channel predictor, wherein the downlink reference signal configuration comprises a transmission pattern of a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising at least a first set of resource elements on which the network node intends to transmit the downlink reference signal.

[0028] According to a twenty-fourth aspect, there is provided a computer readable medium comprising program instructions which, when executed by a network node, cause the network node to perform at least the following: receiving, from a user equipment, a capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation; determining, based on the capability indication, a downlink reference signal configuration to be used for the channel predictor, wherein the downlink reference signal configuration comprises a transmission pattern for a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising at least a first set of resource elements on which the network node intends to transmit the downlink reference signal; and transmitting the downlink reference signal configuration to the user equipment.

[0029] According to a twenty -fifth aspect, there is provided a user equipment comprising: means for receiving a downlink reference signal configuration from a network node, wherein the downlink reference signal configuration comprises a transmission pattern of a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising a first set of resource elements on which the network node intends to transmit the downlink reference signal, and a second set of resource elements on which the network node does not intend to transmit the downlink reference signal; means for monitoring the second set of resource elements for a downlink data channel associated with the downlink reference signal; and means for receiving, from the network node, the downlink data channel on the second set of resource elements based on the monitoring.

[0030] According to a twenty-sixth aspect, there is provided the user equipment of the twenty-fifth aspect, wherein the means for the monitoring are configured to perform the monitoring based on the user equipment being configured to perform channel prediction associated with channel estimation on the second set of resource elements.

[0031] According to a twenty-seventh aspect, there is provided the user equipment of the twenty -fifth or twenty-sixth aspect, further comprising means for generating a capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation; and means for transmitting the capability indication to the network node, wherein the downlink reference signal configuration is based on the capability indication.

[0032] According to a twenty-eight aspect, there is provided the user equipment of the twenty-seventh aspect, further comprising: means for receiving, from the network node, the downlink reference signal on the first set of resource elements; means for determining, per antenna port associated with the downlink reference signal, one or more channel estimates associated with the first set of resource elements in at least one of the frequency domain or the time domain; means for determining, using the channel predictor, per antenna port associated with the downlink reference signal, one or more predicted channel estimates associated with the second set of resource elements in at least one of the frequency domain or the time domain; and means for demodulating the downlink data channel based on a combination of the one or more channel estimates and the one or more predicted channel estimates.

[0033] According to a twenty-ninth aspect, there is provided the user equipment of the twenty-seventh or twenty-eighth aspect, wherein the channel predictor comprises a machine learning model pre-trained based on a set of input data and a set of expected output data, wherein the set of expected output data comprises one or more reference signal channel estimates in at least one of the frequency domain or the time domain per antenna port associated with the downlink reference signal, wherein the set of input data comprises at least one of: a physical resource block level granularity associated with a resource element pattern type of the downlink reference signal in the frequency domain, a symbol position pattern of the downlink reference signal in the time domain, a number of antenna ports associated with the downlink reference signal, a sequence type of the downlink reference signal with one or more initialization seed values, or a downlink precoding technique of the downlink reference signal.

[0034] According to a thirtieth aspect, there is provided the user equipment of any of the twenty-seventh to twenty -ninth aspects, wherein the downlink reference signal configuration further comprises at least one of: an indication for operating the channel predictor in at least one of the frequency domain or the time domain, or at least one data set identifier from the one or more data set identifiers to be applied for the channel predictor.

[0035] According to a thirty-first aspect, there is provided the user equipment of any of the twenty-seventh to thirtieth aspects, wherein the one or more data set identifiers indicate at least one physical resource block density allocation of a reference signal resource element pattern type used for training the channel predictor.

[0036] According to a thirty-second aspect, there is provided the user equipment of any of the twenty-seventh to thirtieth aspects, wherein the one or more data set identifiers indicate at least one physical resource block density allocation of a reference signal resource element pattern type that the channel predictor is capable of predicting.

[0037] According to a thirty-third aspect, there is provided the user equipment of any of the twenty-seventh to thirty-second aspects, wherein the one or more data set identifiers indicate at least one of: one or more carrier frequencies supported by the channel predictor, one or more numerology options supported by the channel predictor, one or more delay spread ranges supported by the channel predictor, one or more Doppler frequency shift or spread values supported by the channel predictor, one or more user equipment speed values supported by the channel predictor, one or more reference signal sequence initialization seed values supported by the channel predictor, a number of reference signal antenna ports supported by the channel predictor, one or more reference signal resource element types supported by the channel predictor, one or more reference signal sequence types supported by the channel predictor, a physical downlink shared channel allocation length or range, in at least one of the frequency domain or the time domain, supported by the channel predictor, one or more precoding types supported by the channel predictor, or a precoding granularity, in at least one of the frequency domain or the time domain, supported by the channel predictor.

[0038] According to a thirty-fourth aspect, there is provided the user equipment of any of the twenty-fifth to thirty-third aspects, wherein the downlink reference signal is a physical downlink shared channel demodulation reference signal, wherein the downlink data channel is a physical downlink shared channel.

[0039] According to a thirty-fifth aspect, there is provided a network node comprising: means for generating a downlink reference signal configuration, wherein the downlink reference signal configuration comprises a transmission pattern for a downlink reference signal in at least one a frequency domain or a time domain, the transmission pattern comprising a first set of resource elements on which the network node intends to transmit the downlink reference signal, and a second set of resource elements on which the network node does not intend to transmit the downlink reference signal; means for transmitting the downlink reference signal configuration to a user equipment; and means for transmitting, to the user equipment, on the second set of resource elements, a downlink data channel associated with the downlink reference signal.

[0040] According to a thirty-sixth aspect, there is provided a method performed by a user equipment, the method comprising: receiving a downlink reference signal configuration from a network node, wherein the downlink reference signal configuration comprises a transmission pattern of a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising a first set of resource elements on which the network node intends to transmit the downlink reference signal, and a second set of resource elements on which the network node does not intend to transmit the downlink reference signal; monitoring the second set of resource elements for a downlink data channel associated with the downlink reference signal; and receiving, from the network node, the downlink data channel on the second set of resource elements based on the monitoring.

[0041] According to a thirty-seventh aspect, there is provided the method of the thirtysixth aspect, wherein the monitoring is performed based on the user equipment being configured to perform channel prediction associated with channel estimation on the second set of resource elements.

[0042] According to a thirty-eighth aspect, there is provided the method of the thirty-sixth or thirty-seventh aspect, further comprising: generating a capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation; and transmitting the capability indication to the network node, wherein the downlink reference signal configuration is based on the capability indication. According to a thirty-ninth aspect, there is provided a method performed by a network node, the method comprising: generating a downlink reference signal configuration, wherein the downlink reference signal configuration comprises a transmission pattern for a downlink reference signal in at least one a frequency domain or a time domain, the transmission pattern comprising a first set of resource elements on which the network node intends to transmit the downlink reference signal, and a second set of resource elements on which the network node does not intend to transmit the downlink reference signal; transmitting the downlink reference signal configuration to a user equipment; and transmitting, to the user equipment, on the second set of resource elements, a downlink data channel associated with the downlink reference signal.

[0043] According to a fortieth aspect, there is provided a computer program comprising instructions which, when executed by a user equipment, cause the user equipment to perform at least the following: receiving a downlink reference signal configuration from a network node, wherein the downlink reference signal configuration comprises a transmission pattern of a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising a first set of resource elements on which the network node intends to transmit the downlink reference signal, and a second set of resource elements on which the network node does not intend to transmit the downlink reference signal; monitoring the second set of resource elements for a downlink data channel associated with the downlink reference signal; and receiving, from the network node, the downlink data channel on the second set of resource elements based on the monitoring.

[0044] According to a forty -first aspect, there is provided a computer program comprising instructions which, when executed by a network node, cause the network node to perform at least the following: generating a downlink reference signal configuration, wherein the downlink reference signal configuration comprises a transmission pattern for a downlink reference signal in at least one a frequency domain or a time domain, the transmission pattern comprising a first set of resource elements on which the network node intends to transmit the downlink reference signal, and a second set of resource elements on which the network node does not intend to transmit the downlink reference signal; transmitting the downlink reference signal configuration to a user equipment; and transmitting, to the user equipment, on the second set of resource elements, a downlink data channel associated with the downlink reference signal. According to a forty-second aspect, there is provided a non-transitory computer readable medium comprising program instructions which, when executed by a user equipment, cause the user equipment to perform at least the following: receiving a downlink reference signal configuration from a network node, wherein the downlink reference signal configuration comprises a transmission pattern of a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising a first set of resource elements on which the network node intends to transmit the downlink reference signal, and a second set of resource elements on which the network node does not intend to transmit the downlink reference signal; monitoring the second set of resource elements for a downlink data channel associated with the downlink reference signal; and receiving, from the network node, the downlink data channel on the second set of resource elements based on the monitoring.

[0045] According to a forty -third aspect, there is provided a non-transitory computer readable medium comprising program instructions which, when executed by a network node, cause the network node to perform at least the following: generating a downlink reference signal configuration, wherein the downlink reference signal configuration comprises a transmission pattern for a downlink reference signal in at least one a frequency domain or a time domain, the transmission pattern comprising a first set of resource elements on which the network node intends to transmit the downlink reference signal, and a second set of resource elements on which the network node does not intend to transmit the downlink reference signal; transmitting the downlink reference signal configuration to a user equipment; and transmitting, to the user equipment, on the second set of resource elements, a downlink data channel associated with the downlink reference signal.

[0046] According to a forty-fourth aspect, there is provided a computer readable medium comprising program instructions which, when executed by a user equipment, cause the user equipment to perform at least the following: receiving a downlink reference signal configuration from a network node, wherein the downlink reference signal configuration comprises a transmission pattern of a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising a first set of resource elements on which the network node intends to transmit the downlink reference signal, and a second set of resource elements on which the network node does not intend to transmit the downlink reference signal; monitoring the second set of resource elements for a downlink data channel associated with the downlink reference signal; and receiving, from the network node, the downlink data channel on the second set of resource elements based on the monitoring.

[0047] According to a forty-fifth aspect, there is provided a computer readable medium comprising program instructions which, when executed by a network node, cause the network node to perform at least the following: generating a downlink reference signal configuration, wherein the downlink reference signal configuration comprises a transmission pattern for a downlink reference signal in at least one a frequency domain or a time domain, the transmission pattern comprising a first set of resource elements on which the network node intends to transmit the downlink reference signal, and a second set of resource elements on which the network node does not intend to transmit the downlink reference signal; transmitting the downlink reference signal configuration to a user equipment; and transmitting, to the user equipment, on the second set of resource elements, a downlink data channel associated with the downlink reference signal.

[0048] BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In the following, various example embodiments will be described in greater detail with reference to the accompanying drawings, in which

[0050] FIG. 1 illustrates an example of a wireless communication network;

[0051] FIG. 2A illustrates the training phase of a machine learning model;

[0052] FIG. 2B illustrates the inference phase of a trained machine learning model;

[0053] FIG. 3 illustrates a signal flow diagram;

[0054] FIG. 4 illustrates three examples of downlink reference signal resource element patterns;

[0055] FIG. 5 illustrates a flow chart;

[0056] FIG. 6 illustrates a flow chart;

[0057] FIG. 7 illustrates a flow chart;

[0058] FIG. 8 illustrates a flow chart;

[0059] FIG. 9 illustrates an example of an apparatus; and

[0060] FIG. 10 illustrates an example of an apparatus.

[0061] DETAILED DESCRIPTION

[0062] The following embodiments are exemplifying. Although the specification may refer to “an”, “one”, or “some” embodiment(s) in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment(s), or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments within the scope of the claims. Furthermore, the words "comprising" and "including" should be understood as not limiting the described embodiments to consist of only those features that have been mentioned, and such embodiments may also contain features that have not been specifically mentioned. Reference numbers, in the description and / or in the claims, serve to illustrate the embodiments with reference to the drawings, without limiting the embodiments to these examples only.

[0063] Some example embodiments described herein may be implemented in a wireless communication network comprising a radio access network based on one or more of the following radio access technologies (RATs): global system for mobile communications (GSM) or any other second generation (2G) radio access technology, universal mobile telecommunication system (UMTS, 3G) based on basic wideband-code division multiple access (W-CDMA), high-speed packet access (HSPA), long term evolution (LTE), LTE- Advanced, fourth generation (4G), fifth generation (5G), 5G new radio (NR), 5G-Advanced (i.e., 3GPP NR Rel-18 and beyond), or sixth generation (6G). Some examples of radio access networks include the universal mobile telecommunications system (UMTS) radio access network (UTRAN), the evolved universal terrestrial radio access network (E-UTRA), or the next generation radio access network (NG-RAN). The wireless communication network may further comprise a core network, and some example embodiments may also be applied to network functions of the core network.

[0064] It should be noted that the embodiments are not restricted to the wireless communication network given as an example, but a person skilled in the art may also apply the solution to other wireless communication networks or systems provided with necessary properties. For example, some example embodiments may also be applied to a communication system based on IEEE 802.11 specifications, or a communication system based on IEEE 802.15 specifications. IEEE is an abbreviation for the Institute of Electrical and Electronics Engineers.

[0065] FIG. 1 depicts an example of a simplified wireless communication network showing some physical and logical entities. The connections shown in FIG. 1 may be physical connections or logical connections. It is apparent to a person skilled in the art that the wireless communication network may also comprise other physical and logical entities than those shown in FIG. 1. The example embodiments described herein are not, however, restricted to the wireless communication network given as an example but a person skilled in the art may apply the example embodiments described herein to other wireless communication networks provided with necessary properties.

[0066] The example wireless communication network shown in FIG. 1 includes a radio access network (RAN) and a core network 110.

[0067] FIG. 1 shows user equipment (UE) 100, 102 configured to be in a wireless connection on one or more communication channels in a radio cell with an access node 104 of a radio access network.

[0068] The access node 104 may comprise a computing device configured to control the radio resources of the access node 104 and to be in a wireless connection with one or more UEs 100, 102. The access node 104 may also be referred to as a base station, a base transceiver station (BTS), an access point, a cell site, a network node, a radio access network node, a RAN node, or a network device. In this description, the terms “access node” and “network node” may be used interchangeably.

[0069] The access node 104 may be, for example, an evolved NodeB (abbreviated as eNB or eNodeB), or a next generation evolved NodeB (abbreviated as ng-eNB), or a next generation NodeB (abbreviated as gNB or gNodeB), providing the radio cell. The access node 104 may include or be coupled to transceivers. From the transceivers of the access node 104, a connection may be provided to an antenna unit that establishes a bi-directional radio link to one or more UEs 100, 102. The antenna unit may comprise an antenna or antenna element, or a plurality of antennas or antenna elements.

[0070] The wireless connection (e.g., radio link) from a UE 100, 102 to the access node 104 may be called uplink (UL) or reverse link, and the wireless connection (e.g., radio link) from the access node 104 to the UE 100, 102 may be called downlink (DL) or forward link. A UE 100 may also communicate directly with another UE 102, and vice versa, via a wireless connection generally referred to as a sidelink (SL). It should be appreciated that the access node 104 or its functionalities may be implemented by using any node, host, server, access point or other entity suitable for providing such functionalities.

[0071] The radio access network may comprise more than one access node 104, in which case the access nodes may also be configured to communicate with one another over wired or wireless links. These links between access nodes may be used for sending and / or receiving control plane signaling and also for routing data from one access node to another access node. The access node 104 may further be connected to a core network (CN) 110. The core network 110 may comprise an evolved packet core (EPC) network and / or a 5thgeneration core network (5GC). The EPC may comprise network entities, such as a serving gateway (S- GW for routing and forwarding data packets), a packet data network gateway (P-GW) for providing connectivity of UEs to external packet data networks, and / or a mobility management entity (MME). The 5GC may comprise one or more network functions, such as at least one of: a user plane function (UPF), an access and mobility management function (AMF), a location management function (LMF), and / or a session management function (SMF).

[0072] The core network 110 may also be able to communicate with one or more external networks 113, such as a public switched telephone network or the Internet, or utilize services provided by them. For example, in 5G wireless communication networks, the UPF of the core network 110 may be configured to communicate with an external data network via an N6 interface. In LTE wireless communication networks, the P-GW of the core network 110 may be configured to communicate with an external data network.

[0073] It should also be understood that the distribution of functions between core network operations and access node operations may differ in future wireless communication networks compared to that of the LTE or 5G, or even be non-existent.

[0074] The illustrated UE 100, 102 is one type of an apparatus to which resources on the air interface may be allocated and assigned. The UE 100, 102 may also be called a wireless communication device, a subscriber unit, a mobile station, a remote terminal, an access terminal, a user terminal, a terminal device, or a user device, just to mention but a few names. The UE 100, 102 may be a computing device operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of computing devices: a mobile phone, a smartphone, a personal digital assistant (PDA), a handset, a computing device comprising a wireless modem (e.g., an alarm or measurement device, etc.), a laptop computer, a desktop computer, a tablet, a game console, a notebook, a multimedia device, a reduced capability (RedCap) device, a wearable device (e.g., a watch, earphones or eyeglasses) with radio parts, a sensor comprising a wireless modem, or a computing device comprising a wireless modem integrated in a vehicle.

[0075] It should be appreciated that the UE 100, 102 may also be a nearly exclusive uplink-only device, of which an example may be a camera or video camera loading images or video clips to a network. The UE 100, 102 may also be a device having capability to operate in an Internet of Things (loT) network, which is a scenario in which objects may be provided with the ability to transfer data over a network without requiring human-to-human or human- to-computer interaction.

[0076] The wireless communication network may also be able to support the usage of cloud services. For example, at least part of core network operations may be carried out as a cloud service (this is depicted in FIG. 1 by “cloud” 114). The UE 100, 102 may also utilize the cloud 114. In some applications, the computation for a given UE may be carried out in the cloud 114 or in another UE.

[0077] The wireless communication network may also comprise a central control entity, such as a network management system (NMS), or the like. The NMS is a centralized suite of software and hardware used to monitor, control, and administer the network infrastructure. The NMS is responsible for a wide range of tasks such as fault management, configuration management, security management, performance management, and accounting management. The NMS enables network operators to efficiently manage and optimize network resources, ensuring that the network delivers high performance, reliability, and security.

[0078] 5G enables using multiple-input and multiple-output (MIMO) antennas in the access node 104 and / or the UE 100, 102, many more base stations or access nodes than an LTE network (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and employing a variety of radio technologies depending on service needs, use cases and / or spectrum available. 5G wireless communication networks may support a wide range of use cases and related applications including video streaming, augmented reality, different ways of data sharing and various forms of machine-type applications, such as (massive) machine-type communications (mMTC), including vehicular safety, different sensors and real-time control.

[0079] In 5G wireless communication networks, access nodes and / or UEs may have multiple radio interfaces, such as below 6 gigahertz (GHz), centimeter wave (cmWave) and millimeter wave (mmWave), and also being integrable with legacy radio access technologies, such as LTE. Integration with LTE may be implemented, for example, as a system, where macro coverage may be provided by LTE, and 5G radio interface access may come from small cells by aggregation to LTE. In other words, a 5G wireless communication network may support both inter-RAT operability (such as interoperability between LTE and 5G) and inter- RI operability (inter-radio interface operability, such as between below 6GHz, cmWave, and mmWave). 5G wireless communication networks may also apply network slicing, in which multiple independent and dedicated virtual sub-networks (network instances) may be created within the same physical infrastructure to run services that have different requirements on latency, reliability, throughput and mobility.

[0080] In one embodiment, an access node 104 may comprise: a radio unit (RU) 103 comprising a radio transceiver (TRX), i.e., a transmitter (Tx) and a receiver (Rx); one or more distributed units (DUs) 105 that may be used for the so-called Layer 1 (LI) processing and real-time Layer 2 (L2) processing; and a central unit (CU) 108 (also known as a centralized unit) that may be used for non-real-time L2 and Layer 3 (L3) processing. The CU 108 may be connected to the one or more DUs 105 for example via an Fl interface. Such an embodiment of the access node 104 may enable the centralization of CUs relative to the cell sites and DUs, whereas DUs may be more distributed and may even remain at cell sites. The CU and DU together may also be referred to as baseband or a baseband unit (BBU). The CU and DU may also be comprised in a radio access point (RAP).

[0081] The CU 108 may be a logical node hosting radio resource control (RRC), service data adaptation protocol (SDAP) and / or packet data convergence protocol (PDCP), of the NR protocol stack for an access node 104. The CU 108 may comprise a control plane (CU-CP), which may be a logical node hosting the RRC and the control plane part of the PDCP protocol of the NR protocol stack for the access node 104. The CU 108 may further comprise a user plane (CU-UP), which may be a logical node hosting the user plane part of the PDCP protocol and the SDAP protocol of the CU for the access node 104.

[0082] The DU 105 may be a logical node hosting radio link control (RLC), medium access control (MAC) and / or physical (PHY) layers of the NR protocol stack for the access node 104. The operations of the DU 105 may be at least partly controlled by the CU 108. It should also be understood that the distribution of functions between the DU 105 and the CU 108 may vary depending on the implementation.

[0083] Cloud computing systems may also be used to provide the CU 108 and / or DU 105. A CU provided by a cloud computing system may be referred to as a virtualized CU (vCU). In addition to the vCU, there may also be a virtualized DU (vDU) provided by a cloud computing system. Furthermore, there may also be a combination, where the DU may be implemented on so-called bare metal solutions, for example application-specific integrated circuit (ASIC) or customer-specific standard product (CSSP) system-on-a-chip (SoC). Edge cloud may be brought into the radio access network by utilizing network function virtualization (NFV) and software defined networking (SDN). Using edge cloud may mean access node operations to be carried out, at least partly, in a computing system operationally coupled to a remote radio head (RRH) or a radio unit (RU) 103 of an access node 104. It is also possible that access node operations may be performed on a distributed computing system or a cloud computing system located at the access node 104. Application of cloud RAN architecture enables RAN real-time functions being carried out at the radio access network (e.g., in a DU 105), and non-real-time functions being carried out in a centralized manner (e.g., in a CU 108).

[0084] 5G (or new radio, NR) wireless communication networks may support multiple hierarchies, where multi-access edge computing (MEC) servers may be placed between the core network 110 and the access node 104. It should be appreciated that MEC may be applied in LTE wireless communication networks as well.

[0085] A 5G wireless communication network (“5G network”) may also comprise a nonterrestrial communication network, such as a satellite communication network, to enhance or complement the coverage of the 5G radio access network. For example, satellite communication may support the transfer of data between the 5G radio access network and the core network 110, enabling more extensive network coverage. Possible use cases may include: providing service continuity for machine-to-machine (M2M) or Internet of Things (loT) devices or for passengers on board of vehicles, or ensuring service availability for critical communications, and future railway, maritime, or aeronautical communications. Satellite communication may utilize geostationary earth orbit (GEO) satellite systems, or low earth orbit (LEO) satellite systems, such as mega-constellations (i.e., systems in which hundreds of (nano)satellites are deployed). Alternatively, the satellites may be an airborne devices, such as an unmanned aerial vehicle (UAV), or a high-altitude platform system (HAPS). A given satellite 106 may provide communication services on Earth via one or more satellite beams. The one or more satellite beams create one or more cells over a given service area that may be bounded by the field of view of the satellite 106.

[0086] It is obvious for a person skilled in the art that the access node 104 depicted in FIG. 1 is just an example of a part of a radio access network, and in practice the radio access network may comprise a plurality of access nodes 104, the UEs 100, 102 may have access to a plurality of radio cells, and the radio access network may also comprise other apparatuses, such as physical layer relay access nodes or other entities. At least one of the access nodes may be a Home eNodeB or a Home gNodeB. A Home gNodeB or a Home eNodeB is a type of access node that may be used to provide indoor coverage inside a home, office, or other indoor environment.

[0087] Additionally, in a geographical area of a radio access network, a plurality of different kinds of radio cells as well as a plurality of radio cells may be provided. Radio cells may be macro cells (or umbrella cells) which may be large cells having a diameter of up to tens of kilometers, or smaller cells such as micro-, femto- or picocells. The access node(s) 104 of FIG. 1 may provide any kind of these cells. A cellular radio network may be implemented as a multilayer access networks including several kinds of radio cells. In multilayer access networks, one access node may provide one kind of a radio cell or radio cells, and thus a plurality of access nodes may be needed to provide such a multilayer access network.

[0088] For fulfilling the need for improving performance of radio access networks, the concept of “plug-and-play” access nodes may be introduced. A radio access network, which may be able to use “plug-and-play” access nodes, may include, in addition to Home eNodeBs or Home gNodeBs, a Home Node B gateway (HNB-GW) (not shown in FIG. 1). An HNB- GW, which may be installed within an operator’s radio access network, may aggregate traffic from a large number of Home eNodeBs or Home gNodeBs back to a core network 110 of the operator.

[0089] 6G wireless communication networks are expected to adopt flexible decentralized and / or distributed computing systems and architecture and ubiquitous computing, with local spectrum licensing, spectrum sharing, infrastructure sharing, and intelligent automated management underpinned by mobile edge computing, artificial intelligence, short-packet communication and blockchain technologies. Key features of 6G may include intelligent connected management and control functions, programmability, integrated sensing and communication, reduction of energy footprint, trustworthy infrastructure, scalability and affordability. In addition to these, 6G is also targeting new use cases covering the integration of localization and sensing capabilities into system definition to unifying user experience across physical and digital worlds.

[0090] Artificial intelligence (Al) and machine learning (ML) may be used to enhance various aspects of wireless communication networks, such as network optimization, beam management, resource allocation, fault detection, maintenance, security, and / or user experience. For example, in beam management, Al and ML algorithms may be used both at the UE side and at the network side to improve beamforming, beam tracking, and / or beam selection, which may be beneficial for maintaining optimal signal strength and quality in high- frequency bands like millimeter-wave (mmWave). The integration of Al and ML in wireless communication networks may result in increased efficiency, adaptability, and scalability.

[0091] In the context of Al and ML, data collection is a process for gathering data by network nodes, management entities, and / or UE(s), for the purpose of training an artificial intelligence or machine learning model, and / or for data analytics and inference.

[0092] An artificial intelligence or machine learning model is a data-driven algorithm that applies artificial intelligence or machine learning techniques to generate a set of outputs based on a set of inputs.

[0093] The training is a process for training an artificial intelligence or machine learning model by learning the relationship between inputs and outputs in a data-driven manner to obtain the trained model to be used for inference.

[0094] The inference involves using a trained Al or ML model to produce a set of outputs (predictions) based on a set of inputs.

[0095] Al or ML model validation is a subprocess of the training, which evaluates the quality of an Al or ML model using a dataset different from the one used for the model training, helping to select model parameters that generalize beyond the training dataset.

[0096] Al or ML model testing is another subprocess of the training, which evaluates the performance of a final Al or ML model using a dataset different from those used for model training and validation. Unlike the model validation, testing does not assume subsequent tuning of the model.

[0097] A UE-side Al or ML model is one whose inference is performed entirely at the UE, while a network-side Al or ML model is one whose inference is performed entirely at the network (e.g., at a gNB).

[0098] A one-sided Al or ML model refers to either a UE-side or network-side Al or ML model. In contrast, a two-sided Al or ML model involves paired models over which joint inference is performed, where the inference is conducted jointly across the UE and the network. This means the first part of the inference is performed by the UE, and the remaining part is performed by the gNB, or vice versa.

[0099] Channel estimation is a process that involves determining the characteristics of a wireless communication channel, such as the path loss, fading, complex value coefficients (i.e., phase and amplitude information), and / or interference. The channel estimate information may be used by the receiver to accurately decode the received data signal (radio signal). The phase and amplitude information may also be referred to as channel state information (CSI).

[0100] A reference signal (RS), such as a demodulation reference signal (DMRS) or a channel state information reference signal (CSI-RS), may be embedded within the transmitted data for the purpose of channel estimation. Reference signal resources are signals associated with sequences (e.g., Pseudo-random or Zadoff-Chu or M-Sequences) that are known to both the transmitter and receiver, providing a reliable basis for channel estimation. When the receiver detects these reference signals, it uses them to measure the channel’s phase and amplitude information (i.e., CSI), enabling the receiver to compensate for any distortions or variations in the data signal caused by the transmission environment. This process is beneficial for maintaining the integrity and quality of the communication link, for example in scenarios involving high mobility or complex propagation conditions. In MIMO systems, reference signals may be used for estimating the CSI for each logical antenna port (orthogonal or non- orthogonal) that is associated with reference signal resources (or transmission path), facilitating spatial multiplexing and beamforming for transmission of data and / or control information.

[0101] The physical downlink shared channel (PDSCH) demodulation reference signal (DMRS) may be used to assist UEs in demodulating and decoding data transmitted by the network (e.g., a gNB) on the PDSCH. The primary purpose of PDSCH DMRS is to provide a known antenna port(s) associated with reference signal resource(s) that the UE can use to estimate the downlink CSI (i.e., effective downlink channel covering the impact of DL transmission precoding, radio channel and receiver for the DMRS reception). PDSCH DMRS is also beneficial in MIMO communication by aiding in spatial multiplexing, allowing the UE to distinguish orthogonal and non-orthogonal antenna ports of DMRS transmitted via different physical transmit antenna elements at the gNB. The DMRS antenna ports may be positioned within the resource elements of one or more physical resource blocks (PRBs) of the PDSCH resources (e.g., in time and / or frequency domain), with its exact location varying depending on the numerology and transmission configuration. PDSCH is physical channel used for transmitting user data in downlink (from the network to the UE 100).

[0102] The sequence for DMRS may be generated by using a specific sequence type (e.g., Pseudo-Random or M-Sequence or Zadoff-Chu) based on a pre-defined pattern known to both the transmitter and receiver, thus facilitating accurate estimation of the channel or CSI. The DMRS sequence may be modulated using schemes such as quadrature phase shift keying (QPSK) or quadrature amplitude modulation (QAM). After modulation, these DMRS symbols may be mapped onto a specific resource element pattern within one or more PRBs associated with the PDSCH.

[0103] For example, the DMRS-DownlinkConfig information element may be included in an RRC configuration to configure downlink demodulation reference signals for PDSCH. In general, DMRS may be associated with specific antenna ports with corresponding resource elements. DMRS antenna ports are logical entities that help the network distinguish channels (i.e., effective channel) or CSI between PDSCH layers transmitted throughout multiple transmit antennas.

[0104] A resource element (RE) is a unit of resource allocation in the time-frequency grid of wireless communication systems associated with applied subcarrier spacing (e.g., 15 or 30 or 60 or 120 or 240 kilohertz). For example, a resource element may represent a single subcarrier in the frequency domain and / or a single OFDM symbol in the time domain. A given resource element may carry a piece of data or control information or a reference signal.

[0105] The DMRS can be transmitted in various schemes, including time-domain, frequency-domain, and beamformed (covering also precoding) DMRS, each suited to different transmission scenarios. Upon receiving the DMRS symbols, the UE may use the DMRS symbols to estimate the channel conditions or CSI for each antenna port (AP) or beam, which is beneficial for coherent demodulation (covering potentially also interference cancellation or mitigation) and decoding of the PDSCH transport block(s). At the UE side, DMRS antenna ports enable the receiver to accurately estimate the channel (i.e., effective channel) or CSI associated with the transmitted PDSCH layer(s) by knowing the exact reference signal configuration, which may include, for example, the antenna port mapping in frequency and time. After the UE has computed the AP-specific DMRS channel estimates based on the DMRS configuration, the UE may use the determined channel estimates for the demodulation of the PDSCH.

[0106] For example, TS 38.211 (version 18.0.0) defines the following configurations for DMRS mapping to physical resources. The UE may assume the PDSCH DMRS being mapped to physical resources according to configuration type 1 or configuration type 2 as given by the higher-layer parameter dmrs-Type. The UE may assume the sequence r(m) is scaled by a factor / PDSCHt0conform with the transmission power specified in TS 38.214 and mapped to resource elements (k, / )paccording to, if the higher-layer parameter dmrs-TypeEnh is configured:

[0107] 47=+fc') {8n + 2k' + A configuration type 1 12n + k' + A configuration type 2, k' = 0,1

[0108] 12n + k' + A + 4 configuration type 2, k' = 2,3 k' = 0,1, 2, 3

[0109] I = 1 + 1' n = 0,1, ... j = 0,1, ..., v - 1

[0110] Otherwise: 1

[0111] (6n + k' + A configuration type 2 k' = 0,1

[0112] I = I + I' n = 0,1, ... j = 0,1, where wf(fc'), wt(Z'), and A are given by Tables 7.4.1.1.2-1 and 7.4.1.1.2-2 of TS 38.211, and the following conditions are fulfilled: the resource elements are within the common resource blocks allocated for PDSCH transmission.

[0113] The reference point for I and the position l0of the first DMRS symbol depend on the mapping type. For PDSCH mapping type A, I is defined relative to the start of the slot, with Z0= 3 if the higher-layer parameter dmrs-TypeA-Position is ‘pos3’ and Z0= 2 otherwise. For PDSCH mapping type B, I is defined relative to the start of the scheduled PDSCH resources, with Zo= 0.

[0114] The position(s) of the DMRS symbols are given by I and the duration ld. For PDSCH mapping type A, ldis the duration between the first orthogonal frequency-division multiplexing (OFDM) symbol of the slot and the last OFDM symbol of the scheduled PDSCH resources in the slot. For PDSCH mapping type B, ldis the duration of the scheduled PDSCH resources.

[0115] The time-domain index Z' and the supported antenna ports p are given by Table 7.4.1.1.2-5 of TS 38.211. Single-symbol DMRS may be used if the higher-layer parameter maxLength in the DMRS-DownlinkConfig information element is not configured. Singlesymbol or double-symbol DMRS may be determined by the associated downlink control information (DCI) if the higher-layer parameter maxLength is equal to ‘len2’. Basic or enhanced DMRS multiplexing may be controlled by the higher-layer parameter dmrs- TypeEnh.

[0116] Table 1 provides an example of type-1 and type-2 DMRS resource element pattern resource overhead in frequency domain over PDSCH allocation per symbol, when all DL DMRS antenna ports are indicated or configured for the UE. In Table 1, “FL” is an abbreviation for “front-loaded”, which refers to the first DMRS symbol before PDSCH reception.

[0117] Table 1. Type-1 and Type-2 DMRS resource overhead in frequency domain per symbol when all DMRS antenna ports are indicated for UE(s).

[0118] As shown in Table 1, when all DL DMRS antenna ports are indicated for UE(s),

[0119] DMRS resource overhead in frequency domain may go up to 100%, leading to very high DMRS resource overhead in frequency domain. It should be noted that, when the maximum number of DMRS antenna ports is configured for the UE, for example 8 APs (type-1), 12 APs (type-2), or 24 APs (e-type2), the current NR specification requires that DL DMRS is allocated fully over the PDSCH allocation (i.e., covering all physical resource blocks and related resource elements assigned for PDSCH bandwidth). In other words, the current NR specification does not support any technique to reduce the frequency density of DMRS.

[0120] Some example embodiments may utilize a channel predictor (e.g., an Al-based or ML-based model) for a downlink reference signal (e.g., PDSCH DMRS or any other downlink reference signal). The channel predictor may provide predictions of the channel conditions (i.e., effective channel) or CSI in frequency and / or time domain for each antenna port associated with the downlink reference signal. Thus, the UE does not need to receive the actual downlink reference signal on the resource elements (in frequency and / or time domain) associated with the predicted channel estimates (and the network does not need to transmit the actual downlink reference signal on those resource elements). Instead, the UE can rely on the predictions made by the channel predictor to estimate the channel conditions (in frequency and / or time domain) for those resource elements.

[0121] This approach can reduce the overhead associated with transmitting reference signals and improve the overall efficiency of the communication system. In other words, the example embodiments described herein may enable resource overhead reduction in frequency and / or time domain for example for PDSCH DMRS (or any other downlink reference signal). The example embodiments enable flexible usage of the reference signal resource element patterns for the resource overhead reduction.

[0122] For example, the channel predictor may be trained with a specific physical resource block (PRB) level granularity associated with a certain reference signal resource element pattern (e.g., DMRS type-1, e-typel, 6G-type, etc.) in frequency domain, and / or symbol position pattern (e.g., every n-th symbol or symbol indices 4, 7, 10 out of 14 symbol in a slot) in time domain, a specific number of antenna ports, a specific sequence type (e.g., pseudo-random) with one or more specific initialization values (e.g., initialization seed values), and a specific downlink precoding technique.

[0123] Some example embodiments are described below using principles and terminology of 5G radio access technology without limiting the example embodiments to 5G radio access technology, however.

[0124] FIG. 2 A illustrates the training phase 201 of a machine learning model 210 (channel predictor) used for channel prediction associated with channel estimation. The training may be performed in a UE 100, 102, for example.

[0125] As an example, the machine learning model 210 may be or comprise a convolutional neural network (CNN). CNNs are designed to process grid-like data, similar to the channel (effective channel) or CSI matrix, wherein the CNN can extract features of the channel. CNNs can also capture temporal and / or frequency domain correlations in channel variations. Therefore, a CNN model can be applied for prediction of the channel (effective channel) or CSI, such that the CNN model predicts non-transmitted resource elements associated with DMRS antenna ports by leveraging measurements associated with transmitted resource elements associated with DMRS antenna ports.

[0126] As another example, the machine learning model 210 may be or comprise a supervised learning model. However, it should be noted that the machine learning model 210 is not limited to these examples, and any other suitable type of machine learning model can be used.

[0127] The machine learning model 210 is trained based on a set of input data 211 and a set of expected output data 212. In the training phase 201, the machine learning model 210 learns the relationship or logic between the set of input data 211 and the expected output data 212. During the training phase 201, all reference signal resource elements (e.g., DMRS REs) with a specific resource element pattern (e.g., DMRS e-typel or e-type2) associated with reference signal antenna ports (e.g., DMRS APs) across the configured PDSCH bandwidth may be transmitted by the network (e.g., network node 104) with a configured set of symbols (e.g., all symbols in a slot or a smaller set) in time domain. The UE 100 may compute or determine corresponding antenna-port-specific channel estimates across the configured PDSCH bandwidth and configured set of symbols in time domain.

[0128] The set of input data 211 of the machine learning model 210 may comprise, per antenna port associated with the downlink reference signal, one or more channel estimates (in at least one of the frequency domain or the time domain) associated with a first set of received resource elements of the downlink reference signal (e.g., PDSCH DMRS). The set of input data 211 further comprises a downlink reference signal configuration associated with the downlink reference signal (i.e., the necessary information about the configuration and characteristics of the downlink reference signal).

[0129] The set of expected output data 212 of the machine learning model 210 may comprise one or more channel estimates (in at least one of the frequency domain or the time domain) per antenna port associated with a second set of received resource elements of the downlink reference signal (e.g., PDSCH DMRS). The expected output data 212 teaches the machine learning 210 about what the output of the machine learning model 210 (i.e., the channel predictions to be made by the ML model) should be.

[0130] The downlink reference signal configuration may comprise, for example, at least one of the following information elements: a type of the downlink reference signal, a physical resource block level granularity associated with a resource element pattern type of the downlink reference signal in frequency domain, a reference signal symbol (e.g., DMRS symbol) position pattern in time domain, a number of antenna ports associated with the downlink reference signal, a sequence type of the downlink reference signal with one or more initialization seed values, and / or a downlink precoding technique of the downlink reference signal. These information elements may be identified by one or more data set identifiers (dataSetIDs).

[0131] The type of the downlink reference signal refers to the specific configuration or variant of the reference signal used in the downlink transmission. Different types of reference signals are designed to meet various requirements and scenarios in wireless communication systems. Each type of downlink reference signal is associated with specific characteristics, such as the pattern of resource elements it occupies, the sequence used for the signal, and the way it is mapped to physical resources. Some examples of the type of the downlink reference signal may include (but are not limited to): DMRS Type-1, DMRS Type-2, DMRS E-Type 1 (Enhanced Type-1), or DMRS 6G-Type. DMRS Type-1 is a standard type of DMRS used in 5G NR (e.g., used for channel estimation in scenarios with lower mobility and simpler propagation conditions). DMRS Type-2 may be used for more complex scenarios, such as those involving multiple antenna ports in MIMO systems. E-Typel is an enhanced version of the standard DMRS Type-1, which may include additional features or modifications to improve performance in more challenging conditions, such as higher mobility or more complex propagation environments. The 6G-Type refers to a type of reference signal that might be used in future 6G networks.

[0132] The symbol position pattern refers to the specific configuration in time domain where a set of reference signal symbol (e.g., DMRS symbol) positions in time domain within a slot for reference signal transmission (e.g., DMRS transmission) are defined. In one example, the symbol positions may be defined as an offset with respect to a specific control symbol, data symbol or reference signal symbol within a slot, such that the offset is always larger than zero. In another example, the symbol position pattern may be an absolute symbol index from the start of the slot. In another example, the symbol position pattern may define the time density of reference signal symbols (e.g., DMRS symbols) within a slot, starting from a specific symbol position till the end of the slot.

[0133] The physical resource block level granularity refers to the detailed allocation of resource elements within the PRBs, which can be specified in the frequency domain. The physical resource block level granularity indicates how the resources are distributed and used for the downlink reference signal.

[0134] The number of antenna ports associated with the downlink reference signal specifies the number of antenna ports that represent the transmission paths of the downlink reference signal, through which the downlink reference signal is transmitted from the network (e.g., gNB) to the UE. In other words, an antenna port (e.g., DMRS port) is a logical representation of a transmission path used to transmit the downlink reference signal (e.g., DMRS) from the network to the UE (i.e., the antenna port does not refer to a physical antenna). Each antenna port corresponds to a different transmission path, and knowing the number of antenna ports helps in understanding the spatial configuration of the downlink reference signal. The downlink reference signal may be mapped to one or more antenna ports. The UE may then use the downlink reference signal received on these antenna port(s) to estimate the channel conditions or CSI or effective channel for each transmission path.

[0135] The “sequence type of the downlink reference signal with one or more initialization seed values” includes the type of sequence used for the downlink reference signal (e.g., pseudo-random sequence) and the initialization seed value(s) that are used to generate the sequence. The sequence type and seed values may be needed for synchronizing the transmitter and receiver.

[0136] The downlink precoding technique refers to the technique used to pre-process the downlink reference signal before transmission to improve signal quality and reduce interference. For example, precoding may involve applying a set of weights to the transmitted signal across multiple antennas to optimize the signal reception at the receiver. Precoding may be codebook-based or non-codebook-based.

[0137] FIG. 2B illustrates the inference phase 202 of the trained machine learning model 220, where the trained machine learning model 220 is used to make channel predictions associated with channel estimation (after the training phase 201 of FIG. 2A is completed).

[0138] During the inference phase 202, the network node 104 may transmit a reduced amount of PRBs associated with reference signal resource elements (e.g., DMRS REs) of a specific resource element pattern (e.g., DMRS e-typel or e-type2) associated with reference signal antenna ports (e.g., DMRS APs) over a reduced set of configured symbols. The UE 100 may perform measurements and determine corresponding channel estimates based on the reduced density PRBs and reduced set of symbols transmitted by the network node 104. The UE 100 may feed this information into the trained machine learning model 220, which then predicts antenna-port-specific channel estimates on the resource elements and PRBs which have not been transmitted by the network node 104 (i.e., on the “gaps” on which the UE 100 does not receive the reference signal). The non-transmitted resource “gaps” may be in frequency and / or time domain.

[0139] In the inference phase 202, the set of input data 221 of the trained machine learning model 220 may comprise, per antenna port associated with the downlink reference signal, one or more channel estimates (in at least one of the frequency domain or the time domain) associated with a set of received resource elements of the downlink reference signal. The set of input data 211 further comprises a downlink reference signal configuration associated with the downlink reference signal (i.e., the necessary information about the configuration and characteristics of the downlink reference signal). Based on the set of input data 221, the trained machine learning model 220 generates output data 222 comprising one or more predicted channel estimates per antenna port associated with the downlink reference signal. The one or more predicted channel estimates are associated with one or more non-received resource elements of the downlink reference signal (i.e., the UE does not need to actually receive the downlink reference signal on the resource elements, for which the channel estimates are predicted). The “one or more predicted channel estimates per antenna port” means that the trained ML model 220 provides one or more predictions of the channel conditions for each logical transmission path (antenna port) associated with the downlink reference signal.

[0140] FIG. 3 illustrates a signal flow diagram according to an example embodiment.

[0141] Referring to FIG. 3, at 301, a UE 100 transmits a capability indication to a network node (access node) 104 of a radio access network, wherein the capability indication indicates that the UE 100 supports channel prediction associated with channel estimation. For example, the capability indication may be comprised in a radio resource control (RRC) message generated by the UE 100. The network node 104 receives the capability indication. The network node 104 may refer to a base station (e.g., a gNB) controlling a serving cell of the UE 100 (i.e., a cell that the UE 100 is connected to).

[0142] The capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation.

[0143] The ’’channel prediction associated with channel estimation” means that the UE 100 is capable of using the channel predictor to predict channel estimates (without receiving an actual reference signal on the resource elements for which the channel estimates are predicted by the channel predictor). The channel predictor associated with the channel estimation means that the channel predictor is used in conjunction with the channel estimation process. For example, the channel predictor may refer to the trained machine learning model 220 described above. Alternatively, the channel predictor may be a non-ML (non-AI) model, or based on a combination of ML and non-ML inference.

[0144] The one or more data set identifiers specify the capabilities of the channel predictor. A given data set identifier may identify a set or subset of reference signal configuration data used for training the channel predictor.

[0145] For example, one of the one or more data set identifiers may indicate at least one physical resource block density allocation of a reference signal resource element pattern type used for training the channel predictor (e.g., at resource element and PRB level). In other words, the channel predictor may have been trained with a specific PRB-level granularity associated with a certain resource element pattern (e.g., DMRS type-1, e-typel, 6G-type, etc.) in frequency domain, and a specific data set identifier may be used to define which PRB density allocation has been used for training the channel predictor (i.e., as an input of the channel predictor).

[0146] Alternatively, the one or more data set identifiers may indicate at least one physical resource block density allocation of a reference signal resource element pattern type that the channel predictor is capable of predicting (which may be the same or different than the PRB density allocation used for training the channel predictor). In other words, in this approach, the capability indication may indicate which PRB density allocation the trained channel predictor model can predict as an output of the channel predictor.

[0147] Alternatively, the one or more data set identifiers may indicate at least one symbol position pattern that the channel predictor is capable of predicting in time domain (which may be the same or different than the symbol position pattern used for training the channel predictor). In other words, in this approach, the capability indication may indicate which symbol position pattern the trained channel predictor model can predict in time as an output of the channel predictor.

[0148] Some examples of the PRB density allocation may include, but are not limited to: an even PRB density allocation (see FIG. 4), an odd PRB density allocation (see FIG. 4), an irregular PRB density allocation (see FIG. 4), or every n-th PRB density allocation, where n>l.

[0149] For example, when the channel predictor has been trained with the “even PRB density allocation” option, it means that the channel predictor can predict antenna ports of resource elements associated with odd-numbered PRBs. In other words, in this case, the model training has been done with even PRBs and corresponding antenna ports and resources therein, and thus the channel predictor can predict the channel estimates associated with odd-numbered PRBs (which are not transmitted by the network node 104). The channel predictor may be trained with a specific reference signal resource element pattern type or combination of resource element pattern type (e.g., DMRS type 1, or 6G-typel, or 6G-typel + type2, or any other 6G-type(s)), such that every n-th odd PRB comprises a reference signal resource element pattern (or combination of patterns) associated with reference signal antenna ports (e.g., DMRS antenna ports) of a downlink data channel’s frequency domain allocation (e.g., PDSCH frequency domain allocation). A non-limiting example of a data set identifier for the “even PRB density allocation” option may be DMRS-typeX-FreqDensityEvenDataSetID#n, where X refers to the specific reference signal resource element pattern type (e.g., DMRS type 1, or 6G-typel, or 6G-typel + type2, or any other 6G-type(s)). It is also possible to have different data set identifiers for different values of n (the larger the value of n, the sparser the allocation of REs for the reference signal).

[0150] As another example, when the channel predictor has been trained with the “odd PRB density allocation” option, it means that the channel predictor can predict antenna ports of resource elements associated with even-numbered PRBs. In other words, in this case, the model training has been done with odd PRBs and corresponding antenna ports and resources therein, and thus the channel predictor can predict the channel estimates associated with even PRBs (which are not transmitted by the network node 104). The channel predictor may be trained with a specific reference signal resource element pattern type or combination of resource element pattern types (e.g., DMRS type 1, or 6G-typel, or 6G-typel + type2, or any other 6G-type(s)), such that every j -th even PRB comprises a reference signal resource element pattern (or combination of patterns) associated with reference signal antenna ports (e.g., DMRS antenna ports) of a downlink data channel’ s frequency domain allocation (e.g., PDSCH frequency domain allocation). A non-limiting example of a data set identifier for the “odd PRB density allocation” option may be DMRS-typeX-FreqDensityOddDataSetID#j, where X refers to the specific reference signal resource element pattern type (e.g., DMRS type 1, or 6G-typel, or 6G-typel + type2, or any other 6G-type(s)). It is possible to have different data set identifiers for different values of j (the larger the value of j, the sparser the allocation of REs for the reference signal).

[0151] In the “irregular PRB density allocation” option, the channel predictor may be trained with a specific reference signal resource element pattern type or combination of resource element pattern types (e.g., DMRS type 1, or 6G-typel, or 6G-typel + type2, or any other 6G-type(s)), such that a combination of every n-th odd and every j-th even PRB comprises a reference signal resource element pattern (or combination of patterns) associated with reference signal antenna ports (e.g., DMRS antenna ports) of a downlink data channel’s frequency domain allocation (e.g., PDSCH frequency domain allocation). A non-limiting example of a data set identifier for the “irregular PRB density allocation” option may be DMRS-typeX-FreqDensityEvenDataSetID#n + DMRS-typeX-FreqDensityOddDataSetID#j , where X refers to the specific reference signal resource element pattern type (e.g., DMRS type 1, or 6G-typel, or 6G-typel + type2, or any other 6G-type(s)).

[0152] As another example, when the channel predictor has been trained with the “symbol position pattern with time density” option, it means that the channel predictor can predict antenna ports of resource elements associated with configured PRB density with configured symbol position pattern with a specific time density. In other words, in this case, the model training has been done with reference signal symbols (e.g., DMRS symbols) with a specific time density of reference signal symbols (e.g., DMRS symbols) and corresponding antenna ports and resources therein, and thus the channel predictor can predict the channel estimates associated with symbol position pattern with density (which are not transmitted by the network node 104). The channel predictor may be trained with a specific symbol position pattern such that configured reference signal symbols (e.g., DMRS symbols) comprise a reference signal resource element pattern (or combination of patterns) associated with reference signal antenna ports (e.g., DMRS antenna ports) of a downlink data channel’s frequency domain allocation (e.g., PDSCH frequency domain allocation) as well as symbol pattern in time domain. A nonlimiting example of a data set identifier for the “symbol position pattern with offset” option may be DMRS-typeX-SymbolPositionPattern-offset#k-DataSetID#j, where X refers to the specific reference signal resource element pattern type (e.g., DMRS type 1, or 6G-typel, or 6G-typel + type2, or any other 6G-type(s)). It is possible to have different data set identifiers for different values of k (the larger the value of k, the sparser the allocation of DMRS symbols in time for the reference signal).

[0153] Alternatively, or additionally, the one or more data set identifiers may indicate at least one of: one or more carrier frequencies supported by the channel predictor, one or more numerology options supported by the channel predictor per carrier frequency, one or more delay spread ranges (in time) supported by the channel predictor, one or more Doppler frequency shift or spread values supported by the channel predictor, one or more UE speed values supported by the channel predictor, one or more reference signal sequence initialization seed values (or a range of values) supported by the channel predictor, a number of reference signal antenna ports supported by the channel predictor, one or more reference signal resource element types supported by the channel predictor, one or more reference signal sequence types supported by the channel predictor, a physical downlink shared channel allocation length (e.g., in PRBs and / or in symbols) or range (in at least one of the frequency domain or the time domain) supported by the channel predictor, one or more precoding types supported by the channel predictor, or a precoding granularity (in at least one of the frequency domain or the time domain) supported by the channel predictor.

[0154] For example, each of the above information elements may be indicated by a separate data set identifier, or a single data set identifier may indicate a certain combination of these information elements. In other words, the capability indication may indicate one or more information elements per each data set identifier, or multiple (a group of) data set identifiers may share part of the information elements with each other.

[0155] A carrier frequency refers to the frequency at which the reference signal is transmitted. By indicating the one or more supported carrier frequencies in the capability indication, the network node 104 can be made aware of which carrier frequencies can be configured for the trained channel predictor of the UE 100. As a non-limiting example, the supported carrier frequencies may be 700 MHz to 3.5 GHz and 7 to 15 GHz.

[0156] The one or more numerology options refer to the different numerology configurations (e.g., subcarrier spacing) used for the reference signal. By indicating the one or more supported numerology options in the capability indication, the network node 104 can be made aware of which subcarrier spacing options can be configured for the trained channel predictor of the UE 100. As a non-limiting example, the one or more supported numerology option may be indicated with L-bit quantized format (e.g., with two bits: ‘00’ for 15 KHz, ‘01’ for 30 KHz, ‘ 10’ for 60KHz, ‘ 11’ for 120KHz).

[0157] The one or more delay spread ranges refer to the time dispersion of the reference signal. By indicating the one or more supported delay spread ranges in the capability indication, the network node 104 can be made aware of whether the trained channel predictor of the UE 100 can be utilized in the presence of a certain delay spread. The network node 104 may have this awareness based on uplink reference signal measurements. As a non-limiting example, the one or more supported delay spread ranges may be indicated with N-bit quantized format (e.g., with two bits indicating four different delay spread values: ‘00’ for 0-10 ns, ‘01’ for 11-30 ns, ‘ 10’ for 31-100 ns, ‘ 11’ for 101- 300ns).

[0158] The one or more Doppler frequency shift or spread values refer to the time variation of the reference signal. By indicating the one or more supported Doppler frequency shift or spread ranges in the capability indication, the network node 104 can be made aware of whether the trained channel predictor of the UE 100 can be utilized in the presence of a Dopper frequency shift or spread. The network node 104 may have this awareness based on uplink reference signal measurements. The one or more UE speed values refer to the time variation of the reference signal. By indicating the one or more supported UE speed values or ranges in the capability indication, the network node 104 can be made aware of whether the trained channel predictor of the UE 100 can be utilized in the presence of UE mobility with a certain UE speed or Doppler frequency shift or Doppler spread. The network node 104 may have this awareness based on uplink reference signal measurements.

[0159] The one or more reference signal sequence initialization seed values refer to the initial value(s) used to generate the sequence (e.g., pseudorandom sequence) for the reference signal. By indicating the one or more supported initialization seed values in the capability indication, the network node 104 can be made aware of which initialization values (e.g., DMRS initialization values) can be configured for the trained channel predictor of the UE 100. As a non-limiting example, the one or more supported initialization seed values may be indicated with K-bit quantized format (e.g., ‘00’ for seed values 0-8000, ‘01’ for seed values 8000-16000, ‘ 10’ for seed values 16000-24000, ‘ 11’ for seed values 24000-32000).

[0160] The number of antenna ports defines the number of antenna ports (i.e., the logical entities) used to transmit the reference signal. By indicating the supported number of antenna ports in the capability indication, the network node 104 can be made aware of up to which total number of reference signal antenna ports (e.g., DMRS antenna ports) the trained channel predictor of the UE 100 can be configured with. For example, the supported number of antenna ports may be 12, 24, 48 or any other number. In an alternative approach, the supported number of antenna ports may indicate how many additional reference signal antenna ports (e.g., additional DMRS antenna ports) the channel predictor can predict (i.e., this would be a smaller number compared to the total number of reference signal antenna ports). This may also be subject to the reference signal type (e.g., DMRS type), for example, due to different RE patterns associated with different types, this capability may be DMRS-type-specific.

[0161] The one or more reference signal resource element types refer to the specific ways that the reference signal is mapped within the time-frequency grid of the radio frame. For example, there may be at least two different types of DMRS resource elements: Type 1 and Type 2. Type 1 (up to 2 antenna ports) uses every second resource element within the symbols allocated to DMRS, effectively utilizing 50% of the available resource elements. Type 2 (up to 2 antenna ports) uses every third resource element within the symbols allocated to DMRS, utilizing about 33% of the available resource elements. The one or more reference signal sequence types refer to the types of sequences (e.g., pseudo-random, Zadoff-Chu, m-sequence, or any other sequence or a combination of sequences) used for the reference signal. By indicating the one or more supported sequence types in the capability indication, the network node 104 can be made aware of which sequence type(s), the trained channel predictor of the UE 100 can be configured with.

[0162] The PDSCH allocation length or range refers to the length or range of the PDSCH allocation in either the frequency domain or the time domain, or in both the frequency domain and the time domain. By indicating the supported PDSCH allocation length or supported allocation range in frequency and / or time domain in the capability indication, the network node 104 can be made aware of up to which number of PDSCH PRBs and / or symbols the UE (or the trained channel predictor of the UE 100) can be configured with. Herein the number of PDSCH PRBs refers to the output of the channel predictor in frequency domain, i.e., how wide PDSCH allocations in frequency domain the channel predictor can be configured with (e.g., 52 PRBs, or 200 PRBs, or 1000 PRBs, etc.). PDSCH symbols refers to the output of the channel predictor in time domain, i.e., what is the length of PDSCH allocation in time that the channel predictor can be configured with.

[0163] The one or more precoding types refer to the types of precoding techniques (e.g., codebook-based, non-codebook-based) used to pre-process the reference signal before transmission. By indicating the one or more precoding types in the capability indication, the network node 104 can be made aware of which DL precoding technique(s) the trained channel predictor of the UE 100 can be configured with. Some examples of precoding types may include (but are not limited to): codebook-based (e.g., type-1, type2, enhanced type 2, further enhanced type 1), or non-codebook based.

[0164] The precoding granularity refers to the level of detail at which the precoding is applied, such as per resource block, per subcarrier, or per symbol, to optimize signal transmission and reception. By indicating the supported precoding granularity in the capability indication, the network node 104 can be aware of which precoder resource block group (PRG) sizes for a downlink data channel (e.g., PDSCH) the trained channel predictor of the UE 100 can be configured with.

[0165] At 302, the network node 104 determines or generates, based on the capability indication, a downlink reference signal configuration to be used for the channel predictor of the UE 100, such that the downlink reference signal configuration is supported by the channel predictor of the UE 100. For example, the downlink reference signal configuration may be determined such that it corresponds to the reference signal configuration used for training the channel predictor.

[0166] The downlink reference signal configuration comprises a transmission pattern for a downlink reference signal in at least one of a frequency domain or a time domain.

[0167] The transmission pattern and / or symbol position pattern comprises or indicates at least a first set of resource elements on which the network node 104 intends to transmit the downlink reference signal. The transmission pattern and / or symbol position pattern may further comprise or indicate a second set of resource elements on which the network node 104 does not intend to transmit the downlink reference signal. In other words, the second set of resource elements refers to resource elements for which the UE 100 is expected or configured to predict the channel (or effective channel) by using the channel predictor (without the network node 104 actually transmitting the downlink reference signal and without the UE 100 actually receiving the downlink reference signal on those resource elements and / or symbols).

[0168] For example, the second set of resource elements may be explicitly indicated in the transmission pattern of the downlink reference signal configuration transmitted from the network node 104.

[0169] Alternatively, the second set of resource elements may not be explicitly indicated in the transmission pattern (i.e., in this case, the transmission pattern may comprise or indicate only the first set of resource elements). In this case, the UE 100 may determine the second set of resource elements (for which the channel prediction is to be performed) based on the first set of resource elements and / or the downlink reference signal configuration used for training the channel predictor (e.g., based on the at least one physical resource block density allocation of the reference signal resource element pattern type used for training the channel predictor). For example, if the channel predictor has been trained to predict the channel estimates associated with odd-numbered PRBs, then the UE 100 may determine or assume that the second set of resource elements corresponds to resource elements of the odd-numbered PRBs.

[0170] Both the first set of resource elements and the second set of resource elements may be comprised in physical resource blocks allocated for a downlink data channel (e.g., PDSCH) associated with the downlink reference signal (e.g., PDSCH DMRS). By not transmitting the downlink reference signal on the second set of resource elements, the resource overhead of the downlink reference signal is reduced, such that the downlink reference signal is not allocated fully over the entire allocation of the associated downlink data channel. I.e., the downlink reference signal is not spread across all the PRBs and related REs and / or configured symbols assigned for the downlink data channel.

[0171] The first set of resource elements may comprise at least one of: one or more frequency resources (e.g., one or more subcarriers), and / or one or more time resources (e.g., one or more OFDM symbols). The second set of resource elements may comprise at least one of: one or more frequency resources (e.g., one or more subcarriers), and / or one or more time resources (e.g., one or more OFDM symbols). The first set of resource elements and the second set of resource elements may be different such that they do not overlap in time and / or frequency.

[0172] The first set of resource elements may be associated with one or more first antenna ports that are equivalent to or different than one or more second antenna ports associated with the second set of resource elements. In other words, the second set of resource elements may be associated with the same antenna port(s) as the first set of resource elements, or the second set of resource elements may be associated with different antenna port(s) than the first set of resource elements.. The one or more first antenna ports and the one or more second antenna ports may be associated with data layers of the downlink data channel associated with the downlink reference signal.

[0173] The downlink reference signal configuration may further comprise at least one of: an indication for operating the channel predictor in at least one of the frequency domain or the time domain, or at least one data set identifier from the one or more data set identifiers to be applied for the channel predictor.

[0174] Alternatively, the network node 104 may generate a separate configuration comprising the at least one of: the indication for operating the channel predictor in at least one of the frequency domain or the time domain, or the at least one data set identifier from the one or more data set identifiers to be applied for the channel predictor, and the network node 104 may transmit this separate configuration to the UE 100 (e.g., via RRC or MAC signaling) in addition to the downlink reference signal configuration.

[0175] At 303, the network node 104 transmits the downlink reference signal configuration to the UE 100. For example, the downlink reference signal configuration may be transmitted via RRC signaling (e.g., in an RRC reconfiguration message) or MAC signaling. The UE 100 receives the downlink reference signal configuration.

[0176] The network node 104 may also indicate the allocation of the downlink data channel (e.g., PDSCH allocation) to the UE 100. For example, the allocation of the downlink data channel may be indicated via one or more time domain resource allocation (TDRA) tables, which define the scheduled resources of the downlink data channel over time slots.

[0177] A non-limiting example of the downlink reference signal configuration (e.g., DL DMRS configuration) is provided in the following with four different data set identifiers (it should be noted that a higher or lower number of data set identifiers than four may be used in an actual configuration). In this example, the “DMRS-DownlinkConfig” information element may be used to configure downlink demodulation reference signals for PDSCH, where the channel predictor can be configured to operate in the frequency domain and / or time domain with the higher layer parameter dmrs-predictor-domain as follows:

[0178] - ASN1 START

[0179] - TAG-DMRS-DOWNLINKCONFIG-START

[0180] DMRS-DownlinkConfig ::= SEQUENCE {

[0181] —Void Text — dmrs-predictor-domain = ENUMERATED {Frequency, Time, FrequencyAndTime} — if dmrs-predictor-domain not configured following dataSetIDs are not valid dmrs-DataSetlds = SEQUENCE { dmrs-PredictorsSetl = dataSetIDl - refers to dataSetID indicated in capability signaling dmrs-PredictorsSet2 = dataSetID2 - refers to dataSetID indicated in capability signaling dmrs-PredictorsSet3 = dataSetID3 - refers to dataSetID indicated in capability signaling dmrs-PredictorsSet4 = dataSetID4 - refers to dataSetID indicated in capability signaling

[0182] }

[0183] —Void text —

[0184] }

[0185] - TAG-DMRS-DOWNLINKCONFIG-STOP

[0186] - ASN1STOP

[0187] At 304, the UE 100 prepares the channel predictor based on the downlink reference signal configuration. For example, in case the channel predictor comprises a CNN model, the preparation may include (but is not limited to) at least one of the following: loading the trained model 220 from memory into a processing unit, initializing the model with pre-trained weights that correspond to the trained model, preparing estimated channel or CSI estimate samples (estimated based on an actually received reference signal) into a suitable format (i.e., corresponding to the format used during the training), or normalizing and / or scaling the input of the trained model similarly as during the model training. This way consistency can be ensured.

[0188] At 305, the network node 104 transmits the downlink reference signal to the UE 100 on the first set of resource elements. For example, the downlink reference signal may comprise (but is not limited to) one of: a physical downlink shared channel demodulation reference signal (PDSCH DMRS), a non-zero power (NZP) channel state information reference signal (CSI-RS) for CSI acquisition or NZP-CSI-RS for time and frequency tracking, or a phase-tracking reference signal (PTRS).

[0189] The downlink reference signal is not transmitted on the second set of resource elements in at least one of the frequency domain or the time domain. In other words, the network node 104 may refrain from transmitting the downlink reference signal on the second set of resource elements, so that the downlink reference signal is transmitted with reduced resource overhead.

[0190] Consequently, the UE 100 does not receive the downlink reference signal on the second set of resource elements. In other words, the UE 100 may be assumed to not receive the second set of resource elements, for which the UE 100 shall perform antenna-port-specific channel prediction (i.e., the UE 100 may not receive any signal on the second set of resource elements).

[0191] Alternatively, the UE 100 may assume that the downlink data channel’s resource allocation (e.g., PDSCH resource allocation) in frequency domain is mapped to the second set of resource elements for which the channel prediction is performed (i.e., the UE 100 may receive data from the network node 104 on the second set of resource elements for which the channel prediction is performed). This option may help to increase the capacity of the data channel such as PDSCH (i.e., increase the throughput of the data channel of a single user or data channels associated with multiple users) by enabling transmission of data associated with one or more users (or UEs) on the reference signal resource elements.

[0192] At 306, the network node 104 transmits a downlink signal to the UE 100. The UE 100 receives the downlink signal. The downlink signal may be transmitted on at least one resource element of the second set of resource elements in at least one of the frequency domain or the time domain. Thus, the second set of resource elements may be utilized to provide an enhanced multiplexing possibility for any downlink signal (instead of using the second set of resource elements to transmit the downlink reference signal). In this case, the UE 100 may monitor the at least one resource element of the second set of resource elements for the downlink signal.

[0193] Alternatively, the network node 104 may not transmit any signal on the second set of resource elements, in which case the downlink signal may be transmitted on another set of resource elements, on which the UE 100 may monitor for the downlink signal.

[0194] The downlink signal may comprise at least one of: a data signal, a control signal, or another reference signal different from the downlink reference signal for which the downlink reference signal configuration is transmitted. For example, the downlink signal may comprise a downlink data channel (e.g., PDSCH) associated with the downlink reference signal (e.g., PDSCH DMRS), in which case the downlink reference signal may be embedded within the downlink data channel to help the receiver (i.e., the UE 100) to estimate the channel conditions for demodulating and / or decoding the downlink data channel.

[0195] At 307, the UE 100 determines, per antenna port (e.g., for each antenna port) associated with the downlink reference signal (or per antenna port of the one or more first antenna ports), one or more channel estimates associated with the first set of resource elements (received resource elements) in at least one of the frequency domain or the time domain. In other words, the one or more channel estimates are associated with the actual received resource elements of the downlink reference signal. The first set of resource elements refer to the resource elements on which the network node 104 actually transmits the downlink reference signal.

[0196] At 308, the UE 100 determines, using the channel predictor, per antenna port (e.g., for each antenna port) associated with the downlink reference signal (or per antenna port of the one or more second antenna ports), one or more predicted channel estimates associated with the second set of resource elements (non-received resource elements) in at least one of the frequency domain or the time domain. In other words, the one or more predicted channel estimates are associated with the non-received resource elements of the downlink reference signal. The second set of resource elements refer to the resource elements on which the network node 104 does not transmit the downlink reference signal (although the network node 104 may transmit another downlink signal on the second set of resource elements, as explained above). The one or more predicted channel estimates may be determined based on the one or more channel estimates associated with the first set of resource elements (i.e., the channel estimates obtained from the received resource elements may be used as input for the channel predictor, together with the downlink reference signal configuration).

[0197] At 309, the UE 100 stacks or combines the one or more channel estimates and the one or more predicted channel estimates, for example such that the combination covers the entire resource allocation of the downlink reference signal.

[0198] At 310, the UE 100 demodulates and / or decodes the downlink signal (e.g., the downlink data channel, such as PDSCH) based on the combination of the one or more channel estimates and the one or more predicted channel estimates.

[0199] FIG. 4 illustrates three examples of DL reference signal resource element patterns 410, 420, 430 (e.g., for DMRS type-1) associated with odd, even, and irregular allocation for a downlink data channel (e.g., PDSCH) allocation of four PRBs 401, 402, 403, 404. In other words, FIG. 4 demonstrates how the reference signal resource elements may be distributed across the frequency domain for different allocation patterns.

[0200] In the odd allocation pattern 410, the reference signal resource elements (i.e., the first set of resource elements 441, 442, 443, 444, 445, 446, 453, 454, 455, 456, 457, 458) are allocated to every odd-numbered PRB of the four PRBs allocated for the downlink data channel. This means that the reference signal resource elements (i.e., the first set of resource elements 441, 442, 443, 444, 445, 446, 453, 454, 455, 456, 457, 458) are placed in the first PRB 401 and in the third PRB 403. In this case, the second set of resource elements 447, 448, 449, 450, 451, 452, 459, 460, 461, 462, 463, 464 (for which the channel predictor predicts the channel estimates) may be comprised in the even-numbered PRBs of the four PRBs allocated for the downlink data channel (i.e., in the second PRB 402 and in the fourth PRB 404). This pattern reduces overhead by using only the odd-numbered PRBs for the reference signal, allowing even-numbered PRBs to be used for any other DL signal (e.g., data signal, control signal, or another type of reference signal).

[0201] In the even allocation pattern 420, the reference signal resource elements (i.e., the first set of resource elements 441, 442, 443, 444, 445, 446, 453, 454, 455, 456, 457, 458) are allocated to every even-numbered PRB of the four PRBs allocated for the downlink data channel. This means that the reference signal resource elements (i.e., the first set of resource elements 441, 442, 443, 444, 445, 446, 453, 454, 455, 456, 457, 458) are placed in the second PRB 402 and in the fourth PRB 404 of the downlink data channel allocation. In this case, the second set of resource elements 447, 448, 449, 450, 451, 452, 459, 460, 461, 462, 463, 464 (for which the channel predictor predicts the channel estimates) may be comprised in the odd- numbered PRBs of the four PRBs allocated for the downlink data channel (i.e., in the first PRB 401 and in the third PRB 403). This pattern reduces overhead by using only the even- numbered PRBs for the reference signal, allowing odd-numbered PRBs to be used for any other DL signal (e.g., data signal, control signal, or another type of reference signal).

[0202] In general, every n-th reference signal resource elements (i.e., the first set of resource elements) may be allocated to every n-th (n>l, for example n=2) PRB of the four PRBs allocated for the downlink data channel. For example, in case n=2, the reference signal resource elements (i.e., the first set of resource elements) are placed in the second PRB 402 and in the fourth PRB 404 of the downlink data channel allocation. In this case, the second set of resource elements (for which the channel predictor predicts the channel estimates) may be comprised in the first PRB 401 and third PRB 403 of the four PRBs allocated for the downlink data channel. This pattern reduces overhead by using only the every n-th PRBs for the reference signal, allowing other PRBs to be used for any other DL signal (e.g., data signal, control signal, or another type of reference signal).

[0203] The irregular allocation pattern 430 combines both the odd and even allocations in an irregular manner. For example, the reference signal resource elements (i.e., the first set of resource elements) may be placed in the first PRB 401, the third PRB 403 and the fourth PRB 404 (but not in the second PRB 402) allocated for the downlink data channel. In this case, the second set of resource elements (for which the channel predictor predicts the channel estimates) may be comprised in the second PRB 402. The irregular allocation can be tailored to specific channel conditions or network requirements, providing flexibility in optimizing the balance between resource overhead of the reference signal and data transmission efficiency.

[0204] FIG. 5 illustrates a flow chart according to an example embodiment of a method for indicating a channel prediction capability. The method of FIG. 5 may be performed by an apparatus 900 depicted in FIG. 9. For example, the apparatus 900 may be, or comprise, or be comprised in, a user equipment (UE) 100, 102.

[0205] Referring to FIG. 5, in block 501, the user equipment 100, 102 generates a capability indication (or a message comprising the capability indication), the capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation.

[0206] In block 502, the user equipment 100, 102 transmits the capability indication to a network node 104.

[0207] In block 503, the user equipment 100, 102 receives, from the network node 104, based on the capability indication, a downlink reference signal configuration to be used for the channel predictor.

[0208] The downlink reference signal configuration comprises a transmission pattern of a downlink reference signal in at least one of a frequency domain or a time domain.

[0209] The transmission pattern comprises at least a first set of resource elements on which the network node 104 intends to transmit the downlink reference signal. The transmission pattern may further comprise a second set of resource elements on which the network node 104 does not intend to transmit the downlink reference signal.

[0210] The downlink reference signal configuration may further comprise at least one of an indication for operating the channel predictor in at least one of the frequency domain or the time domain, or at least one data set identifier from the one or more data set identifiers to be applied for the channel predictor.

[0211] The first set of resource elements may be associated with one or more first antenna ports that are equivalent to or different than one or more second antenna ports associated with the second set of resource elements.

[0212] The user equipment 100, 102 may receive, from the network node 104, the downlink reference signal on the first set of resource elements. The user equipment 100, 102 may determine, per antenna port associated with the downlink reference signal, one or more channel estimates associated with the first set of resource elements in at least one of the frequency domain or the time domain.

[0213] The user equipment 100, 102 may determine, using the channel predictor, per antenna port associated with the downlink reference signal, one or more predicted channel estimates associated with the second set of resource elements in at least one of the frequency domain or the time domain.

[0214] The user equipment 100, 102 may demodulate a downlink data channel associated with the downlink reference signal based on a combination of the one or more channel estimates and the one or more predicted channel estimates. The downlink reference signal is not received on the second set of resource elements in at least one of the frequency domain or the time domain.

[0215] The user equipment 100, 102 may receive a downlink signal from the network node on at least one resource element of the second set of resource elements in at least one of the frequency domain or the time domain. The downlink signal may comprise at least one of: a data signal, a control signal, or another reference signal different from the downlink reference signal for which the downlink reference signal configuration is received.

[0216] The channel predictor may comprise a machine learning model 220 pre-trained based on a set of input data and a set of expected output data.

[0217] The set of expected output data may comprise one or more reference signal channel estimates in at least one of the frequency domain or the time domain per antenna port associated with the downlink reference signal.

[0218] The set of input data may comprise at least one of: a physical resource block level granularity associated with a resource element pattern type of the downlink reference signal in the frequency domain, a symbol position pattern of the downlink reference signal in the time domain, a number of antenna ports associated with the downlink reference signal, a sequence type of the downlink reference signal with one or more initialization seed values, or a downlink precoding technique of the downlink reference signal.

[0219] The one or more data set identifiers may indicate at least one of: at least one physical resource block density allocation of a reference signal resource element pattern type used for training the channel predictor, at least one physical resource block density allocation of a reference signal resource element pattern type that the channel predictor is capable of predicting, at least one reference signal symbol position pattern that the channel predictor is capable of predicting in the time domain, one or more carrier frequencies supported by the channel predictor, one or more numerology options supported by the channel predictor, one or more delay spread ranges supported by the channel predictor, one or more Doppler frequency shift or spread values supported by the channel predictor, one or more user equipment speed values supported by the channel predictor, one or more reference signal sequence initialization seed values supported by the channel predictor, a number of reference signal antenna ports supported by the channel predictor, one or more reference signal resource element types supported by the channel predictor, one or more reference signal sequence types supported by the channel predictor, a physical downlink shared channel allocation length or range, in at least one of the frequency domain or the time domain, supported by the channel predictor, one or more precoding types supported by the channel predictor, or a precoding granularity, in at least one of the frequency domain or the time domain, supported by the channel predictor.

[0220] The downlink reference signal may comprise, for example, one of: a physical downlink shared channel demodulation reference signal, a channel state information reference signal, or a phase-tracking reference signal.

[0221] FIG. 6 illustrates a flow chart according to an example embodiment of a method for indicating a channel prediction capability. The method of FIG. 6 may be performed by an apparatus 1000 depicted in FIG. 10. For example, the apparatus 1000 may be, or comprise, or be comprised in, a network node 104 of a radio access network.

[0222] Referring to FIG. 6, in block 601, the network node 104 receives, from a user equipment 100, 102, a capability indication indicating that the user equipment 100, 102 supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation.

[0223] In block 602, the network node 104 determines, based on the capability indication, a downlink reference signal configuration to be used for the channel predictor.

[0224] The downlink reference signal configuration comprises a transmission pattern for a downlink reference signal in at least one of a frequency domain or a time domain.

[0225] The transmission pattern comprises at least a first set of resource elements on which the network node 104 intends to transmit the downlink reference signal. The transmission pattern may further comprise a second set of resource elements on which the network node 104 does not intend to transmit the downlink reference signal.

[0226] The downlink reference signal configuration may further comprise at least one of: an indication for operating the channel predictor in at least one of the frequency domain or the time domain, or at least one data set identifier from the one or more data set identifiers to be applied for the channel predictor.

[0227] In block 603, the network node 104 transmits the downlink reference signal configuration to the user equipment 100, 102.

[0228] The one or more data set identifiers may indicate at least one of: at least one physical resource block density allocation of a reference signal resource element pattern type used for training the channel predictor, at least one physical resource block density allocation of a reference signal resource element pattern type that the channel predictor is capable of predicting, at least one reference signal symbol position pattern that the channel predictor is capable of predicting in the time domain, one or more carrier frequencies supported by the channel predictor, one or more numerology options supported by the channel predictor, one or more delay spread ranges supported by the channel predictor, one or more Doppler frequency shift or spread values supported by the channel predictor, one or more user equipment speed values supported by the channel predictor, one or more reference signal sequence initialization seed values supported by the channel predictor, a number of reference signal antenna ports supported by the channel predictor, one or more reference signal resource element types supported by the channel predictor, one or more reference signal sequence types supported by the channel predictor, a physical downlink shared channel allocation length or range, in at least one of the frequency domain or the time domain, supported by the channel predictor, one or more precoding types supported by the channel predictor, or a precoding granularity, in at least one of the frequency domain or the time domain, supported by the channel predictor.

[0229] The network node 104 may transmit the downlink reference signal to the user equipment 100, 102 on the first set of resource elements, wherein the downlink reference signal is not transmitted on the second set of resource elements in at least one of the frequency domain or the time domain.

[0230] The network node 104 may transmit a downlink signal to the user equipment 100, 102 on at least one resource element of the second set of resource elements in at least one of the frequency domain or the time domain.

[0231] The downlink signal may comprise at least one of: a data signal, a control signal, or another reference signal different from the downlink reference signal for which the downlink reference signal configuration is transmitted.

[0232] The downlink reference signal may comprise one of: a physical downlink shared channel demodulation reference signal, a channel state information reference signal, or a phase-tracking reference signal.

[0233] FIG. 7 illustrates a flow chart according to an example embodiment of a method for improving data channel throughput. The method of FIG. 7 may be performed by an apparatus 900 depicted in FIG. 9. For example, the apparatus 900 may be, or comprise, or be comprised in, a user equipment (UE) 100, 102, such as a smartphone or any other type of UE.

[0234] This example embodiment may help to increase the capacity of the data channel such as PDSCH (i.e., increase the throughput of the data channel) by enabling transmission of data on some of the reference signal resource elements.

[0235] Referring to FIG. 7, in block 701, the user equipment 100, 102 receives a downlink reference signal configuration from a network node 104, wherein the downlink reference signal configuration comprises a transmission pattern of a downlink reference signal in at least one of a frequency domain or a time domain. For example, the downlink reference signal configuration may be comprised in a radio resource control message.

[0236] The transmission pattern comprises a first set of resource elements on which the network node 104 intends to transmit the downlink reference signal, and a second set of resource elements on which the network node 104 does not intend to transmit the downlink reference signal.

[0237] In block 702, the user equipment 100, 102 monitors the second set of resource elements for a downlink data channel associated with the downlink reference signal.

[0238] For example, the downlink reference signal may comprise a physical downlink shared channel demodulation reference signal, and the downlink data channel may comprise a physical downlink shared channel.

[0239] The monitoring may be performed based on the user equipment 100, 102 ( or channel predictor) being configured to perform channel prediction associated with channel estimation on the second set of resource elements. In other words, if the UE 100, 102 is configured with the channel prediction, the UE 100, 102 may assume the second set of resource elements (not carrying the downlink reference signal information) to be mapped for the allocation of the downlink data channel (e.g., PDSCH allocation) on the scheduled time and / or frequency resources upon receiving the scheduling of the downlink data channel from the network node 104.

[0240] In block 703, based on the monitoring, the user equipment 100, 102 receives, from the network node 104, the downlink data channel on the second set of resource elements.

[0241] In other words, the UE 100 may receive the downlink data channel (e.g., PDSCH) on the second set of resource elements for which the channel prediction may be configured, and that are configured in the configured time and / or frequency resources of the indicated allocation of the downlink data channel (e.g., PDSCH allocation).

[0242] The first set of resource elements may be associated with one or more first antenna ports that are equivalent to or different than one or more second antenna ports that may be associated with the second set of resource elements.

[0243] Prior to receiving the downlink reference signal configuration, the user equipment 100, 102 may generate a capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation. The user equipment 100, 102 may transmit the capability indication to the network node 104, and the downlink reference signal configuration may be received based on transmitting the capability indication. That is, the downlink reference signal configuration may be based on the capability indication.

[0244] The user equipment 100, 102 may receive, from the network node 104, the downlink reference signal on the first set of resource elements. The user equipment 100, 102 may determine, per antenna port associated with the downlink reference signal, one or more channel estimates associated with the first set of resource elements in at least one of the frequency domain or the time domain. The user equipment 100, 102 may determine, using the channel predictor, per antenna port associated with the downlink reference signal, one or more predicted channel estimates associated with the second set of resource elements in at least one of the frequency domain or the time domain. The user equipment 100, 102 may demodulate and / or decode the downlink data channel based on a combination of the one or more channel estimates and the one or more predicted channel estimates.

[0245] The channel predictor may comprise a machine learning model pre-trained based on a set of input data and a set of expected output data. The set of expected output data may comprise one or more reference signal channel estimates in at least one of the frequency domain or the time domain per antenna port associated with the downlink reference signal. The set of input data may comprise at least one of a physical resource block level granularity associated with a resource element pattern type of the downlink reference signal in the frequency domain, a symbol position pattern of the downlink reference signal in the time domain, a number of antenna ports associated with the downlink reference signal, a sequence type of the downlink reference signal with one or more initialization seed values, or a downlink precoding technique of the downlink reference signal.

[0246] The downlink reference signal configuration may further comprise at least one of an indication for operating the channel predictor in at least one of the frequency domain or the time domain, or at least one data set identifier from the one or more data set identifiers to be applied for the channel predictor.

[0247] The one or more data set identifiers may indicate at least one physical resource block density allocation of a reference signal resource element pattern type used for training the channel predictor.

[0248] Alternatively, the one or more data set identifiers may indicate at least one physical resource block density allocation of a reference signal resource element pattern type that the channel predictor is capable of predicting.

[0249] Alternatively, the one or more data set identifiers may indicate at least one reference signal symbol position pattern that the channel predictor is capable of predicting in the time domain.

[0250] Alternatively, or additionally, the one or more data set identifiers indicate at least one of one or more carrier frequencies supported by the channel predictor, one or more numerology options supported by the channel predictor, one or more delay spread ranges supported by the channel predictor, one or more Doppler frequency shift or spread values supported by the channel predictor, one or more user equipment speed values supported by the channel predictor, one or more reference signal sequence initialization seed values supported by the channel predictor, a number of reference signal antenna ports supported by the channel predictor, one or more reference signal resource element types supported by the channel predictor, one or more reference signal sequence types supported by the channel predictor, a physical downlink shared channel allocation length or range, in at least one of the frequency domain or the time domain, supported by the channel predictor, one or more precoding types supported by the channel predictor, or a precoding granularity, in at least one of the frequency domain or the time domain, supported by the channel predictor.

[0251] FIG. 8 illustrates a flow chart according to an example embodiment of a method for improving data channel throughput. The method of FIG. 8 may be performed by an apparatus 1000 depicted in FIG. 10. For example, the apparatus 1000 may be, or comprise, or be comprised in, a network node 104 of a radio access network.

[0252] This example embodiment may help to increase the capacity of the data channel such as PDSCH (i.e., increase the throughput of the data channel) by enabling transmission of data on some of the reference signal resource elements.

[0253] Referring to FIG. 8, in block 801, the network node 104 generates a downlink reference signal configuration, wherein the downlink reference signal configuration comprises a transmission pattern for a downlink reference signal in at least one a frequency domain or a time domain.

[0254] The transmission pattern comprises a first set of resource elements on which the network node 104 intends to transmit the downlink reference signal, and a second set of resource elements on which the network node 104 does not intend to transmit the downlink reference signal.

[0255] In block 802, the network node 104 transmits the downlink reference signal configuration to a user equipment 100.

[0256] The network node 104 may transmit the downlink reference signal to the user equipment 100 on the first set of resource elements.

[0257] The network node 104 may transmit, to the user equipment 100, on the second set of resource elements, a downlink data channel associated with the downlink reference signal.

[0258] Prior to generating the downlink reference signal configuration, the network node 104 may receive, from the user equipment 100, a capability indication indicating that the user equipment 100 supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation. The downlink reference signal configuration may be generated based on the capability indication.

[0259] The blocks, related functions, and information exchanges (messages) described above by means of FIG. 3 and FIGS. 5 to 8 are in no absolute chronological order, and some of them may be performed simultaneously or in an order differing from the described one. Other functions can also be executed between them or within them, and other information may be sent, and / or other rules applied. Some of the blocks or part of the blocks or one or more pieces of information can also be left out or replaced by a corresponding block or part of the block or one or more pieces of information.

[0260] 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.

[0261] FIG. 9 illustrates an example of an apparatus 900 comprising means for performing one or more of the example embodiments (e.g., the method of FIG. 5 or FIG. 7, or the functionalities of the UE 100 of FIG. 3) described above. For example, the apparatus 900 may be an apparatus such as, or comprising, or comprised in, a user equipment (UE) 100, 102. The user equipment may also be called a wireless communication device, a subscriber unit, a mobile station, a remote terminal, an access terminal, a user terminal, a terminal device, or a user device. The apparatus 900 may comprise a circuitry or a chipset applicable for realizing one or more of the example embodiments described above. For example, the apparatus 900 may comprise at least one processor 910. The at least one processor 910 interprets instructions (e.g., computer program instructions) and processes data. The at least one processor 910 may comprise one or more programmable processors. The at least one processor 910 may comprise programmable hardware with embedded firmware and may, alternatively or additionally, comprise one or more application-specific integrated circuits (ASICs).

[0262] The at least one processor 910 is coupled to at least one memory 920. The at least one processor is configured to read and write data to and from the at least one memory 920. The at least one memory 920 may comprise one or more memory units. The memory units may be volatile or non-volatile. It is to be noted that there may be one or more units of nonvolatile memory and one or more units of volatile memory or, alternatively, one or more units of non-volatile memory, or, alternatively, one or more units of volatile memory. Volatile memory may be for example random-access memory (RAM), dynamic random-access memory (DRAM) or synchronous dynamic random-access memory (SDRAM). Non-volatile memory may be for example read-only memory (ROM), programmable read-only memory (PROM), electronically erasable programmable read-only memory (EEPROM), flash memory, optical storage or magnetic storage. In general, memories may be referred to as non- transitory computer readable media. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM). The at least one memory 920 stores computer readable instructions that are executed by the at least one processor 910 to perform one or more of the example embodiments described above. For example, non-volatile memory stores the computer readable instructions, and the at least one processor 910 executes the instructions using volatile memory for temporary storage of data and / or instructions. The computer readable instructions may refer to computer program code.

[0263] The computer readable instructions may have been pre-stored to the at least one memory 920 or, alternatively or additionally, they may be received, by the apparatus, via an electromagnetic carrier signal and / or may be copied from a physical entity such as a computer program product. Execution of the computer readable instructions by the at least one processor 910 causes the apparatus 900 to perform one or more of the example embodiments described above. That is, the at least one processor and the at least one memory storing the instructions may provide the means for providing or causing the performance of any of the methods and / or blocks described above.

[0264] In the context of this document, a “memory” or “computer-readable media” or “computer-readable medium” may be any non-transitory media or medium or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. The term “non- transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

[0265] The apparatus 900 may further comprise, or be connected to, an input unit 930. The input unit 930 may comprise one or more interfaces for receiving input. The one or more interfaces may comprise for example one or more temperature, motion and / or orientation sensors, one or more cameras, one or more accelerometers, one or more microphones, one or more buttons and / or one or more touch detection units. Further, the input unit 930 may comprise an interface to which external devices may connect to.

[0266] The apparatus 900 may also comprise an output unit 940. The output unit may comprise or be connected to one or more displays capable of rendering visual content, such as a light emitting diode (LED) display, a liquid crystal display (LCD) and / or a liquid crystal on silicon (LCoS) display. The output unit 940 may further comprise one or more audio outputs. The one or more audio outputs may be for example loudspeakers.

[0267] The apparatus 900 further comprises a connectivity unit 950. The connectivity unit 950 enables wireless connectivity to one or more external devices. The connectivity unit 950 comprises at least one transmitter and at least one receiver that may be integrated to the apparatus 900 or that the apparatus 900 may be connected to. The at least one transmitter comprises at least one transmission antenna, and the at least one receiver comprises at least one receiving antenna. The connectivity unit 950 may comprise an integrated circuit or a set of integrated circuits that provide the wireless communication capability for the apparatus 900. Alternatively, the wireless connectivity may be a hardwired application-specific integrated circuit (ASIC). The connectivity unit 950 may also provide means for performing at least some of the blocks or functions of one or more example embodiments described above. The connectivity unit 950 may comprise one or more components, such as: power amplifier, digital front end (DFE), analog-to-digital converter (ADC), digital-to-analog converter (DAC), frequency converter, (de)modulator, and / or encoder / decoder circuitries, controlled by the corresponding controlling units.

[0268] It is to be noted that the apparatus 900 may further comprise various components not illustrated in FIG. 9. The various components may be hardware components and / or software components.

[0269] FIG. 10 illustrates an example of an apparatus 1000 comprising means for performing one or more of the example embodiments (e.g., the method of FIG. 6 or FIG. 8, or the functionalities of the network node 104 of FIG. 3) described above. For example, the apparatus 1000 may be an apparatus such as, or comprising, or comprised in, a network node 104 of a radio access network.

[0270] The apparatus 1000 may comprise, for example, a circuitry or a chipset applicable for realizing one or more of the example embodiments described above. The apparatus 1000 may be an electronic device comprising one or more electronic circuitries. The apparatus 1000 may comprise a communication control circuitry 1010 such as at least one processor, and at least one memory 1020 storing instructions 1022 which, when executed by the at least one processor, cause the apparatus 1000 to carry out one or more of the example embodiments described above. Such instructions 1022 may, for example, include computer program code (software). The at least one processor and the at least one memory storing the instructions may provide the means for providing or causing the performance of any of the methods and / or blocks described above.

[0271] The processor is coupled to the memory 1020. The processor is configured to read and write data to and from the memory 1020. The memory 1020 may comprise one or more memory units. The memory units may be volatile or non-volatile. It is to be noted that there may be one or more units of non-volatile memory and one or more units of volatile memory or, alternatively, one or more units of non-volatile memory, or, alternatively, one or more units of volatile memory. Volatile memory may be for example random-access memory (RAM), dynamic random-access memory (DRAM) or synchronous dynamic random-access memory (SDRAM). Non-volatile memory may be for example read-only memory (ROM), programmable read-only memory (PROM), electronically erasable programmable read-only memory (EEPROM), flash memory, optical storage or magnetic storage. In general, memories may be referred to as non-transitory computer readable media. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM). The memory 1020 stores computer readable instructions that are executed by the processor. For example, non-volatile memory stores the computer readable instructions, and the processor executes the instructions using volatile memory for temporary storage of data and / or instructions. The computer readable instructions may have been pre-stored to the memory 1020 or, alternatively or additionally, they may be received, by the apparatus, via an electromagnetic carrier signal and / or may be copied from a physical entity such as a computer program product. Execution of the computer readable instructions causes the apparatus 1000 to perform one or more of the functionalities described above.

[0272] The memory 1020 may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and / or removable memory. The memory may comprise a configuration database for storing configuration data, such as a current neighbour cell list, and, in some example embodiments, structures of frames used in the detected neighbour cells.

[0273] The apparatus 1000 may further comprise or be connected to a communication interface 1030, such as a radio unit, comprising hardware and / or software for realizing communication connectivity with one or more wireless communication devices according to one or more communication protocols. The communication interface 1030 comprises at least one transmitter (Tx) and at least one receiver (Rx) that may be integrated to the apparatus 1000 or that the apparatus 1000 may be connected to. The communication interface 1030 may provide means for performing some of the blocks and / or functions (e.g., transmitting and receiving) for one or more example embodiments described above. The communication interface 1030 may comprise one or more components, such as: power amplifier, digital front end (DFE), analog-to-digital converter (ADC), digital-to-analog converter (DAC), frequency converter, (de)modulator, and / or encoder / decoder circuitries, controlled by the corresponding controlling units.

[0274] The communication interface 1030 provides the apparatus with radio communication capabilities to communicate in the wireless communication network. The communication interface may, for example, provide a radio interface to one or more UEs 100, 102. The apparatus 1000 may further comprise or be connected to another interface towards a core network 110, such as the network coordinator apparatus or AMF, and / or to other access nodes of the wireless communication network.

[0275] The apparatus 1000 may further comprise a scheduler 1040 that is configured to allocate radio resources. The scheduler 1040 may be configured along with the communication control circuitry 1010 or it may be separately configured.

[0276] It is to be noted that the apparatus 1000 may further comprise various components not illustrated in FIG. 10. The various components may be hardware components and / or software components.

[0277] As used in this application, 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 (including digital signal processor(s), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone, 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 (for example firmware) for operation, but the software may not be present when it is not needed for operation.

[0278] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry 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 server, a cellular network device, or other computing or network device.

[0279] The techniques and methods described herein may be implemented by various means. For example, these techniques may be implemented in hardware (one or more devices), firmware (one or more devices), software (one or more modules), or combinations thereof. For a hardware implementation, the apparatus(es) of example embodiments may be implemented within one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), graphics processing units (GPUs), processors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof. For firmware or software, the implementation can be carried out through modules of at least one chipset (for example procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in a memory unit and executed by processors. The memory unit may be implemented within the processor or externally to the processor. In the latter case, it can be communicatively coupled to the processor via various means, as is known in the art. Additionally, the components of the systems described herein may be rearranged and / or complemented by additional components in order to facilitate the achievements of the various aspects, etc., described with regard thereto, and they are not limited to the precise configurations set forth in the given figures, as will be appreciated by one skilled in the art.

[0280] It will be obvious to a person skilled in the art that, as technology advances, the inventive concept may be implemented in various ways within the scope of the claims. The embodiments are not limited to the example embodiments described above, but may vary within the scope of the claims. Therefore, all words and expressions should be interpreted broadly, and they are intended to illustrate, not to restrict, the embodiments.

Claims

CLAIMS1. A user equipment comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the user equipment at least to: generate a capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation; transmit the capability indication to a network node; and receive, from the network node, based on the capability indication, a downlink reference signal configuration to be used for the channel predictor, wherein the downlink reference signal configuration comprises a transmission pattern of a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising at least a first set of resource elements on which the network node intends to transmit the downlink reference signal.

2. The user equipment of claim 1, wherein the transmission pattern further comprises a second set of resource elements on which the network node does not intend to transmit the downlink reference signal, wherein the first set of resource elements is associated with one or more first antenna ports that are equivalent to or different than one or more second antenna ports associated with the second set of resource elements.

3. The user equipment of claim 2, further being caused to: receive, from the network node, the downlink reference signal on the first set of resource elements; determine, per antenna port associated with the downlink reference signal, one or more channel estimates associated with the first set of resource elements in at least one of the frequency domain or the time domain; and determine, using the channel predictor, per antenna port associated with the downlink reference signal, one or more predicted channel estimates associated with the second set of resource elements in at least one of the frequency domain or the time domain.

584. The user equipment of claim 3, further being caused to: demodulate a downlink data channel associated with the downlink reference signal based on a combination of the one or more channel estimates and the one or more predicted channel estimates.

5. The user equipment of any of claims 3 to 4, wherein the downlink reference signal is not received on the second set of resource elements in at least one of the frequency domain or the time domain.

6. The user equipment of any of claims 2 to 5, further being caused to: receive a downlink signal from the network node on at least one resource element of the second set of resource elements in at least one of the frequency domain or the time domain, wherein the downlink signal comprises at least one of: a data signal, a control signal, or another reference signal different from the downlink reference signal for which the downlink reference signal configuration is received.

7. The user equipment of any preceding claim, wherein the channel predictor comprises a machine learning model pre-trained based on a set of input data and a set of expected output data, wherein the set of expected output data comprises one or more reference signal channel estimates in at least one of the frequency domain or the time domain per antenna port associated with the downlink reference signal, wherein the set of input data comprises at least one of: a physical resource block level granularity associated with a resource element pattern type of the downlink reference signal in the frequency domain, a symbol position pattern of the downlink reference signal in the time domain, a number of antenna ports associated with the downlink reference signal, a sequence type of the downlink reference signal with one or more initialization seed values, or59a downlink precoding technique of the downlink reference signal.

8. The user equipment of any preceding claim, wherein the downlink reference signal configuration further comprises at least one of: an indication for operating the channel predictor in at least one of the frequency domain or the time domain, or at least one data set identifier from the one or more data set identifiers to be applied for the channel predictor.

9. The user equipment of any preceding claim, wherein the one or more data set identifiers indicate at least one physical resource block density allocation of a reference signal resource element pattern type used for training the channel predictor.

10. The user equipment of any of claims 1 to 8, wherein the one or more data set identifiers indicate at least one physical resource block density allocation of a reference signal resource element pattern type that the channel predictor is capable of predicting.

11. The user equipment of any preceding claim, wherein the one or more data set identifiers indicate at least one reference signal symbol position pattern that the channel predictor is capable of predicting in the time domain.

12. The user equipment of any preceding claim, wherein the one or more data set identifiers indicate at least one of: one or more carrier frequencies supported by the channel predictor, one or more numerology options supported by the channel predictor, one or more delay spread ranges supported by the channel predictor, one or more Doppler frequency shift or spread values supported by the channel predictor, one or more user equipment speed values supported by the channel predictor, one or more reference signal sequence initialization seed values supported by the channel predictor, a number of reference signal antenna ports supported by the channel predictor,60one or more reference signal resource element types supported by the channel predictor, one or more reference signal sequence types supported by the channel predictor, a physical downlink shared channel allocation length or range, in at least one of the frequency domain or the time domain, supported by the channel predictor, one or more precoding types supported by the channel predictor, or a precoding granularity, in at least one of the frequency domain or the time domain, supported by the channel predictor.

13. The user equipment of any preceding claim, wherein the downlink reference signal comprises one of: a physical downlink shared channel demodulation reference signal, a channel state information reference signal, or a phase-tracking reference signal.

14. A network node comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the network node at least to: receive, from a user equipment, a capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation; determine, based on the capability indication, a downlink reference signal configuration to be used for the channel predictor, wherein the downlink reference signal configuration comprises a transmission pattern for a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising at least a first set of resource elements on which the network node intends to transmit the downlink reference signal; and transmit the downlink reference signal configuration to the user equipment.

15. The network node of claim 14, wherein the transmission pattern further comprises a second set of resource elements on which the network node does not intend to transmit the downlink reference signal.6116. The network node of claim 15, further being caused to: transmit the downlink reference signal to the user equipment on the first set of resource elements; and transmit a downlink signal to the user equipment on at least one resource element of the second set of resource elements in at least one of the frequency domain or the time domain, wherein the downlink signal comprises at least one of: a data signal, a control signal, or another reference signal different from the downlink reference signal for which the downlink reference signal configuration is transmitted.

17. A method performed by a user equipment, the method comprising: generating a capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation; transmitting the capability indication to a network node; and receiving, from the network node, based on the capability indication, a downlink reference signal configuration to be used for the channel predictor, wherein the downlink reference signal configuration comprises a transmission pattern of a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising at least a first set of resource elements on which the network node intends to transmit the downlink reference signal.

18. A method performed by a network node, the method comprising: receiving, from a user equipment, a capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation; determining, based on the capability indication, a downlink reference signal configuration to be used for the channel predictor,wherein the downlink reference signal configuration comprises a transmission pattern for a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising at least a first set of resource elements on which the network node intends to transmit the downlink reference signal; and transmitting the downlink reference signal configuration to the user equipment.

19. A non-transitory computer readable medium comprising program instructions which, when executed by a user equipment, cause the user equipment to perform at least the following: generating a capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation; transmitting the capability indication to a network node; and receiving, from the network node, based on the capability indication, a downlink reference signal configuration to be used for the channel predictor, wherein the downlink reference signal configuration comprises a transmission pattern of a downlink reference signal in at least one of a frequency domain or a time domain, the transmission pattern comprising at least a first set of resource elements on which the network node intends to transmit the downlink reference signal.

20. A non-transitory computer readable medium comprising program instructions which, when executed by a network node, cause the network node to perform at least the following: receiving, from a user equipment, a capability indication indicating that the user equipment supports channel prediction associated with channel estimation, wherein the capability indication comprises one or more data set identifiers indicating a reference signal configuration used for training of a channel predictor associated with the channel estimation; determining, based on the capability indication, a downlink reference signal configuration to be used for the channel predictor, wherein the downlink reference signal configuration comprises a transmission pattern for a downlink reference signal in at least one of a frequency domain or a time domain,the transmission pattern comprising at least a first set of resource elements on which the network node intends to transmit the downlink reference signal; and transmitting the downlink reference signal configuration to the user equipment.

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