PRIORITY CLAIM

[0001] This application claims the benefit of priority to United States

Provisional Patent Application Serial No. 62/714,017, filed August 2, 2018, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] Embodiments pertain to wireless communications. Some embodiments relate to wireless networks including 3 GPP (Third Generation

Partnership Project) networks, and 3 GPP LTE (Long Term Evolution) networks, Fifth Generation (5G) networks, and/or New Radio (NR) networks. Some embodiments relate to radio link measurement (RLM). Some embodiments relate to channel state information reference signals (CSI-RSs), including CSI-RSs for RLM. Some embodiments relate to methods of adaptive allocation of CSI-RS for RLM

BACKGROUND

[00Q3] Efficient use of the resources of a wireless network is important to provide bandwidth and acceptable response times to the users of the wireless network. However, often there are many devices trying to share the same resources and some devices may be limited by the communication protocol they use or by their hardware bandwidth. Moreover, wireless devices may need to operate with both newer protocols and with legacy device protocols. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] FIG. 1 A is a functional diagram of an example network in accordance with some embodiments;

[0005] FIG. IB is a functional diagram of another example network in accordance with some embodiments;

[0006] FIG. 2 illustrates a block diagram of an example machine in accordance with some embodiments;

[0007] FIG. 3 illustrates a user device in accordance with some aspects;

[0008] FIG. 4 illustrates a base station in accordance with some aspects;

[0009] FIG. 5 illustrates an exemplary communication circuitry according to some aspects;

[0010] FIG. 6 illustrates an example of a radio frame structure in accordance with some embodiments;

[0011] FIG. 7A and FIG 7B illustrate example frequency resources in accordance with some embodiments;

[0012] FIG. 8 illustrates the operation of a method of communication m accordance with some embodiments; and

[0013] FIG. 9 illustrates the operation of another method of communication in accordance with some embodiments.

DETAILED DESCRIPTION [0014] The following description and the drawings sufficiently illustrate specific embodiments to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. Portions and features of some embodiments may be included in, or substituted for, those of other embodiments. Embodiments set forth in the claims encompass all available equivalents of those claims.

[0015] FIG. 1 A is a functional diagram of an example network in accordance with some embodiments. FIG. IB is a functional diagram of another example netw'ork in accordance with some embodiments. In references herein, z “FIG 1” may include FIG. 1A and FIG. I B. In some embodiments, the network 100 may be a Third Generation Partnership Project (3 GPP) network. In some embodiments, the network 150 may be a 3GPP network, a new radio (NR) network and/or Fifth Generation (5G) network. Other networks may be used in some embodiments. In some embodiments, a network may include one or more of: one or more components shown in FIG. 1 A; one or more components shown in FIG. IB; and one or more additional components. Some embodiments may not necessarily include all components shown in FIG. 1 A and FIG. IB

[0016] The network 100 may comprise a radio access network (RAN) 101 and the core network 120 (e.g., shown as an evolved packet core (EPC)) coupled together through an SI interface 115 For convenience and brevity sake, only a portion of the core network 120, as well as the RAN 101, is shown. In some embodiments, the RAN 101 may include one or more of: one or more components of an evolved universal terrestrial radio access network (E-UTRAN), one or more components of an NR network, and/or one or more other components.

[0017] The core network 120 may include a mobility management entity

(MME) 122, a serving gateway (serving GW) 124, and packet data network gateway (PDN GW) 126. In some embodiments, the networks 100, 150 may include (and/or support) one or more Evolved Node-B’s (eNBs) 104 and/or one or more Next Generation Node-B’s (gNBs) 105. The eNBs 104 and/or gNBs 105 may operate as base stations for communicating with User Equipment (UE) 102. In some embodiments, one or more eNBs 104 may be configured to operate as gNBs 105 Embodiments are not limited to the number of eNBs 104 shown in FIG. 1A or to the number of gNBs 105 shown in FIG IB Embodiments are also not limited to the connectivity of components shown in FIG. 1 A.

[0018] It should be noted that references herein to an eNB 104 or to a gNB105 are not limiting. In some embodiments, one or more operations, methods and/or techniques (such as those described herein) may be practiced by a base station component (and/or other component), including but not limited to a gNB105, an eNB 104, a serving cell, a transmit receive point (TRP) and/or other. In some embodiments, the base station component may be configured to operate in accordance with one or more of: a 3 GPP LTE protocol/standard, an NR

protocol/standard, a Fifth Generation (5G) protocol/standard; and/or other protocol/standard, although the scope of embodiments is not limited in this respect.

[0019] Descriptions herein of one or more operations, techniques and/or methods practiced by a component (such as the UE 102, eNB 104, gNB 105 and/or other) are not limiting. In some embodiments, one or more of those operations, techniques and/or methods may be practiced by another component.

[0020] The MME 122 manages mobility aspects in access such as gateway selection and tracking area list management. The serving GW 124 terminates the interface toward the RAN 101, and routes data packets between the RAN 101 and the core network 120. In addition, it may be a local mobility anchor point for inter- eNB handovers and also may provide an anchor for inter-3 GPP mobility. The serving GW 124 and the MME 122 may be implemented in one physical node or separate physical nodes.

[0021] In some embodiments, UEs 102, the eNB 104 and/or gNB 105 may be configured to communicate Orthogonal Frequency Division Multiplexing (OFDM) communication signals over a multicarrier communication channel in accordance with an Orthogonal Frequency Division Multiple Access (OFDMA) communication technique.

[0022] In some embodiments, the network 150 may include one or more components configured to operate in accordance with one or more 3 GPP standards, including but not limited to an NR standard. The network 150 shown in FIG. IB may include a next generation RAN (NG-RAN) 155, which may include one or more gNBs 105. In some embodiments, the network 150 may include the E~ UTRAN 160, which may ⁷ include one or more eNBs. The E-UTRAN 160 may be similar to the RAN 101 described herein, although the scope of embodiments is not limited in this respect.

[0023] In some embodiments, the network 150 may include the MME 165, which may be similar to the MME 122 described herein, although the scope of embodiments is not limited in this respect. In some embodiments, the network 150 may include the SGW 170, which may be similar to the SGW 124 described herein, although the scope of embodiments is not limited in this respect.

[0024] Embodiments are not limited to the number or type of components shown in FIG. IB. Embodiments are also not limited to the connectivity of components shown in FIG. IB. [0025] FIG. 2 illustrates a block diagram of an example machine in accordance with some embodiments. The machine 200 is an example machine upon which any one or more of the techniques and/or methodologies discussed herein may be performed. In alternative embodiments, the machine 200 may operate as a standalone device or may be connected (e.g., networked) to other machines. The machine 200 may be a UE 102, eNB 104, gNB 105, access point (AP), station (STA), user, device, mobile device, base station, another device, or any machine capable of executing instructions (sequential or otherwise) that specify actions to be taken by that machine. Further, while only a single machine is illustrated, the term “machine” shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein, such as cloud computing, software as a service (SaaS), other computer cluster configurations.

[0026] The machine (e.g., computer system) 200 may include a hardware processor 202 (e.g., a central processing unit (CPU), a graphics processing unit (GPU), a hardware processor core, or any combination thereof), a mam memory 204 and a static memor 206, some or all of which may communicate with each other via an interlink (e.g., bus) 208. The machine 200 may further include one or more of 210-228.

[0027] The storage device 216 may include a machine readable medium

222 on which is stored one or more sets of data structures or instructions 224 (e.g., software) embodying or utilized by any one or more of the techniques or functions described herein. The instructions 224 may also reside, completely or at least partially, within the main memory 204, within static memory 206, or within the hardware processor 202 during execution thereof by the machine 200. In an example, one or any combination of the hardware processor 202, the main memory 204, the static memory 206, or the storage device 216 may constitute machine readable media. In some embodiments, the machine readable medium may be or may include a non-transitory computer-readable storage medium. In some embodiments, the machine readable medium may be or may include a computer- readable storage medium.

[0028] While the machine readable medium 222 is illustrated as a single medium, the term "machine readable medium" may include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) configured to store the one or more instructions 224. The term “machine readable medium” may include any mediu that is capable of storing, encoding, or carrying instructions for execution by the machine 200 and that cause the machine 200 to perform any one or more of the techniques of the present disclosure, or that is capable of storing, encoding or carrying data structures used by or associated with such instructions. Non-limiting machine readable medium examples may include solid-state memories, and optical and magnetic

media. Specific examples of machine readable media may include: non-volatile memory, such as semiconductor memory devices (e.g., Electrically Programmable Read-Only Memor (EPROM), Electrically Erasable Programmable Read-Only Memory' (EEPROM)) and flash memory' ^· devices; magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; Random Access Memory (RAM); and CD-ROM and DVD-ROM disks. In some examples, machine readable media may include non-transitory machine readable media. In some examples, machine readable media may include machine readable media that is not a transitory propagating signal.

[0029] The instructions 224 may further be transmitted or received over a communications network 226 using a transmission medium via the network interface device 220 utilizing any one of a number of transfer protocols. In an example, the network interface device 220 may include a plurality' of antennas to wirelessly communicate using at least one of single-input multiple-output (SIMO), multiple-input multiple-output (MEMO), or multiple-input single-output (MISO) techniques. In some examples, the network interface device 220 may wirelessly communicate using Multiple User MEMO techniques. The term“transmission medium” shall be taken to include any intangible medium that is capable of storing, encoding or carrying instructions for execution by the machine 200, and includes digital or analog communications signals or other intangible medium to facilitate communication of such software.

[0030] FIG. 3 illustrates a user device in accordance with some aspects. In some embodiments, the user device 300 may be a mobile device. In some embodiments, the user device 300 may be or may be configured to operate as a User Equipment (UE). The user device 300 may be suitable for use as a UE 102 as depicted in FIG. 1 , in some embodiments. It should be noted that in some embodiments, a UE, an apparatus of a UE, a user device or an apparatus of a user device may include one or more of the components shown in one or more of FIGs.

2, 3, and 5. In some embodiments, such a HE, user device and/or apparatus may include one or more additional components. In some aspects, the user device 300 may include one or more of components 305-370 and/or other component(s).

[0031] FIG. 4 illustrates a base station in accordance with some aspects. In some embodiments, the base station 400 may be or may be configured to operate as one or more of: an eNB 104, a gNB 105 and/or other. The base station 400 may be suitable for use as an eNB 104 as depicted in FIG. 1 , in some embodiments. The base station 400 may be suitable for use as an eNB 104 and/or a gNB 105 as depicted in FIG. 1, in some embodiments. It should be noted that in some embodiments, an eNB, an apparatus of an eNB, a gNB, an apparatus of a gNB, a base station and/or an apparatus of a base station may include one or more of the components shown in one or more of FIGs. 2, 4, and 5. In some embodiments, such an eNB, gNB, base station and/or apparatus may include one or more additional components. The base station 400 may include one or more of components 405-450 and/or other components.

[0032] FIG. 5 illustrates an exemplary communication circuitry according to some aspects. It should be noted that a device, such as a UE 102, eNB 104, gNB 105, the user device 300, the base station 400, the machine 200 and/or other device may include one or more components of the communication circuitry 500, in some aspects.

[0033] The communication circuitry 500 may include protocol processing circuitry 505, which may implement one or more of medium access control (MAC), radio link control (RFC), packet data convergence protocol (PDCP), radio resource control (RRC) and non-access stratum (NAS) functions. Protocol processing circuitry 505 may include one or more processing cores (not shown) to execute instructions and one or more memory structures (not shown) to store program and data information. The communication circuitry 500 may further include digital baseband circuitry 510, which may implement one or more physical layer (PITY) functions.

[0034] The communication circuitry 500 may further include transmit circuitry 515, receive circuitry 520 and/or antenna array circuitry 530 The communication circuitry 500 may further include radio frequency (RF) circuitry 525. In an aspect of the disclosure, RF circuitry' 525 may include multiple parallel RF chains for one or more of transmit or receive functions, each connected to one or more antennas of the antenna array 530.

[0035] In some embodiments, processing circuitry' may perform one or more operations described herein and/or other operation(s). In a non-limiting example, the processing circuitry may include one or more components such as the processor 202, application processor 305, baseband module 310, application processor 405, baseband module 410, protocol processing circuitry 505, digital baseband circuitry 510, similar component(s) and/or other component(s).

[0036] In some embodiments, a transceiver may transmit one or more elements (including but not limited to those described herein) and/or receive one or more elements (including but not limited to those described herein). In a non- limiting example, the transceiver may include one or more components such as the radio front end module 315, radio front end module 415, transmit circuitry 515, receive circuitry 520, radio frequency circuitry 525, similar component(s) and/or other component(s).

[0037] Although the UE 102, eNB 104, gNB 105, user device 300, base station 400, machine 200 and/or other device described herein may each be illustrated as haying several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software-configured elements, such as processing elements including digital signal processors (DSPs), one or more microprocessors, field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), radio-frequency integrated circuits (RFICs) and combinations of various hardware and logic circuitry for performing at least the functions described herein. In some embodiments, the functional elements may refer to one or more processes operating on one or more processing elements.

[0038] It should be noted that in some embodiments, an apparatus of the UE

102, eNB 104, gNB 105, machine 200, user device 300 and/or base station 400 may include various components shown in FIGs. 2-5. Accordingly, techniques and operations described herein that are performed by a device may be performed by an apparatus of the device, in some embodiments.

[0039] FIG. 6 illustrates an example of a radio frame structure in accordance with some embodiments. FIGs. 7A and 7B illustrate example frequency resources in accordance with some embodiments. In references herein,“FIG. 7” may include FIG. 7A and FIG. 7B. It should be noted that the examples shown in FIGs. 6-7 may illustrate some or all of the concepts and techniques described herein in some cases, but embodiments are not limited by the examples. For instance, embodiments are not limited by the name, number, type, size, ordering, arrangement and/or other aspects of the time resources, symbol periods, frequency resources, PRBs and other elements as shown in FIGs. 6-7. Although some of the elements shown in the examples of FIGs. 6-7 may be included in a 3GPP LTE standard, 5G standard, NR standard and/or other standard, embodiments are not limited to usage of such elements that are included in standards.

[0040] An example of a radio frame structure that may be used m some aspects is shown in FIG. 6. In this example, radio frame 600 has a duration of 10ms. Radio frame 600 is divided into slots 602 each of duration 0.5 ms, and numbered from 0 to 19. Additionally, each pair of adjacent slots 602 numbered 2i and 2i + Ί, where i is an integer, is referred to as a subframe 601.

[0041] In some aspects using the radio frame format of FIG. 6, each subframe 601 may include a combination of one or more of downlink control information, downlink data information, uplink control information and uplink data information. The combination of information types and direction may be selected independently for each subframe 602.

[0042] Referring to FIGs. 7 A and 7B, in some aspects, a sub-component of a transmitted signal consisting of one subcarrier in the frequency domain and one symbol interval in the time domain may be termed a resource element. Resource elements may be depicted in a grid form as shown in FIG. 7A and FIG. 7B. In some aspects, illustrated in FIGs. 7A, resource elements may be grouped into rectangular resource blocks 700.

[0043] In accordance with some embodiments, the gNB 105 may transmit control signaling to the UE 102. The control signaling may configure the UE 102 with a plurality' of channel state information reference signal (CSI-RS) resource sets in the downlink. Each CSI-RS resource set may include a plurality of CSI-RS resources. One of the CSI-RS resource sets may be allocated for radio link measurement (RLM) at the UE 102. The control signaling may configure the UE 102 with a set of sounding reference signal (SRS) resources in the uplink. The gNB 105 may determine a level of frequency selectivity in the downlink based on the SRS received from the UE 102 in the uplink. The gNB 105 may determine an RLM CSI-RS frequency density based on the level of frequency selectivity in the downlink, wherein the RLM CSI-RS frequency density is to be configured for the CSI-RS resource set allocated for RLM. The RLM CSI-RS frequency density may be: higher for higher levels of frequency selectivity in the downlink, and lower for lower levels of frequency selectivity in the downlink. The gNB 105 may transmit CSI-RS of the CSI-RS resource set allocated for RLM. The CSI-RS may be encoded in accordance with the RLM CSI-RS frequency density. These

embodiments are described in more detail below.

f 0044] FIG. 8 illustrates the operation of a method of communication m accordance with some embodiments. FIG. 9 illustrates the operation of another method of communication in accordance with some embodiments. Embodiments of the methods 800, 900 may include additional or even fewer operations or processes in comparison to what is illustrated in FIGs. 8-9. Embodiments of the methods 800, 900 are not necessarily limited to the chronological order that is shown in FIGs. 8-9.

[00451 In some embodiments, a gNB 105 may perform one or more operations of the method 800, but embodiments are not limited to performance of the method 800 and/or operations of it by the gNB 105. In some embodiments, another device and/or component (including but not limited to the UE 102 and/or eNB 105) may perform one or more operations that may be the same as, similar to, reciprocal to and/or related to an operation of the method 800.

[0046] In some embodiments, a UE 102 may perform one or more operations of the method 900, but embodiments are not limited to performance of the method 900 and/or operations of it by the UE 102. In some embodiments, another device and/or component (including but not limited to the eNB 104 and/or gNB 105) may perform one or more operations that may be the same as, similar to, reciprocal to and/or related to an operation of the method 900.

[0047] Discussion of various operations, techniques and/or concepts regarding one of the methods 800, 900 and/or other method may be applicable to one of the other methods, although the scope of embodiments is not limited in this respect.

[0048] One or more of the techniques, operations and/or methods described herein may he performed by a device other than an eNB 104, gNB 105, and UE 102, including but not limited to a Wi-Fi access point (AP), station (STA) and/or other.

[0049] In some embodiments, an apparatus of a devi ce (including but not limited to the UE 102, gNB 105 and/or other) may comprise memory that is configurable to store one or more elements, and the apparatus may use them for performance of one or more operations. The apparatus may include processing circuitry, which may perform one or more operations (including but not limited to operation(s) of the method 800, the method 900 and/or other methods described herein). The processing circuitry' may include a baseband processor. The baseband circuitry and/or the processing circuitry may perform one or more operations described herein. The apparatus may include a transceiver to transmit and/or receive one or more blocks, messages and/or other elements.

[0050] Embodiments are not limited by references herein to transmission, reception and/or exchanging of elements such as frames, messages, requests, indicators, signals or other elements. In some embodiments, such an element may be generated, encoded or otherwise processed by processing circuitry for transmission by a transceiver or other component, in some cases. In some embodiments, such an element may be received by a transceiver or other component, and may be decoded, detected or otherwise processed by processing circuitry. In some embodiments, the processing circuitry _' and the transceiver may be included in a same apparatus. In some embodiments, the transceiver may be separate from the apparatus that comprises the processing circuitry, in some embodiments.

[0051] One or more of the elements (such as messages, operations and/or other) described herein may be included in a 3GPP protocol, 3GPP LTE protocol, 4G protocol, 5G protocol, NR protocol and/or other protocol, but embodiments are not limited to usage of those elements. In some embodiments, other elements may be used, including other element(s) in a same standard/protocol, other element(s) in another standard/protocol and/or other. In addition, the scope of embodiments is not limited to usage of elements that are included in standards. [0052] In some embodiments, the UE 102 may be arranged to operate in accordance with an NR protocol. In some embodiments, the gNB 105 may be arranged to operate m accordance with an NR protocol.

[0053] At operation 805, the gNB 105 may exchange control signaling with the UE 102. The control signaling may include one or more control messages, one or more other messages and/or other, in some embodiments. In some embodiments, the gNB 105 may perform one or more of: transmit control signaling; transmit control signaling to the UE 102; receive control signaling; receive control signaling from the UE 102; and/or other. In some embodiments, the UE 102 may perform one or more of; transmit control signaling; transmit control signaling to the gNB 105; receive control signaling; receive control signaling from the gNB 105; and/or other. In a non-limiting example, the control signaling may include one or more of radio resource control (RRC) raessage(s), higher layer message(s), a UE capability message and/or other.

[0054] In some embodiments, the control signaling may configure the UE

102 with a plurality' of CSI-RS resource sets in the downlink. Each CSI-RS resource set may include a plurality of CSI-RS resources. One of the CSI-RS resource sets may be allocated for radio link measurement (RLM) at the UE 102. In some embodiments, the control signaling may configure the UE 102 with a set of sounding reference signal (SRS) resources in the uplink. In some embodiments, the control signaling may include a spatial relation information (SRS- SpatialRelationlnfo) field that includes information identifying a spatial relationship between: one or more downlink beams mapped to the CSI-RS resource set allocated for RLM, and one or more uplink beams mapped to the set of SRS resources. In some embodiments, the control signaling may indicate a plurality of subbands for which the UE 102 is to perform per-subband signal quality' measurements. The control signaling may include other information and/or additional information, in some embodiments.

[0055] In some embodiments, the CSI-RS resource set allocated for RLM at the UE 102 may be allocated for monitoring, by the gNB 105, of a level of downlink radio quality for unreliable reception that corresponds to a target block error rate (BLER) for a hypothetical physical downlink control channel (PDCCH)

transmission, although the scope of embodiments is not limited in this respect. [0056] At operation 810, the gNB 105 may determine a level of frequency selectivity. In some embodiments, the determination of the level of frequency selectivity may include one or more of operations 815-835 and/or other operation(s). It should be noted embodiments are not limited to determination of a level of frequency selectivity. In some embodiments, the gNB 105 may determine one or more of: information/parameter(s) related to frequency selectivity;

informal! on/parameter(s) that characterize frequency selectivity;

information/parameteris) that indicate whether a medium (such as the medium between the gNB 105 and the UE 102) is frequency selective, frequency non- selective and/or other; other information/parameter(s) related to the medium; and/or other.

[0057] At operation 815, the gNB 105 may receive a sounding reference signal (SRS) In some embodiments, the gNB 105 may receive the SRS from the UE 102, although the scope of embodiments is not limited in this respect.

[0058] In some embodiments, the gNB 105 may determine a level of frequency selectivity in the downlink based on the SRS received from the UE 102 in the uplink. In some embodiments, the gNB 105 may determine the level of frequency selectivity for the downlink based on reception of the SRS in the uplink in accordance with a reciprocity between the uplink and the downlink for a medium between the gNB 105 and the UE 102. In some embodiments, the gNB 105 may determine the level of frequency sel ectivity for the downlink based on reception of the SRS in the uplink in accordance with an assumption of at least partial reciprocity between the uplink and the downlink for a medium between the gNB 105 and the UE 102.

[QQ59] At operation 820, the gNB 105 may determine a delay spread. At operation 825, the gNB 105 may determine a coherence bandwidth. Embodiments are not limited to usage of these parameters (delay spread and coherence

bandwidth). In some embodiments, the gNB 105 may determine one or more of the following parameters, and may use those parameters for determination of the level of frequency selectivity (operation 810), determination of the RLM CSI frequency density (operation 840) and/or other operation(s): delay spread; coherence bandwidth; one or more other parameters.

[0060] In some embodiments, the gNB 105 may determine a delay spread of the SRS received from the UE 102. The gNB 105 may determine the level of frequency selectivity based on a predetermined mapping between the level of frequency selectivity and the delay spread, wherein the level of frequency selectivity' is higher for higher values of the delay spread and is lower for lower values of the delay spread.

[0061] In some embodiments, the gNB 105 may compare the delay spread to one or more thresholds to determine the level of frequency selectivity. For instance, if the delay spread is greater than or equal to a threshold, the gNB 105 may determine the level of frequency selectivity as“high.” If the delay spread is less than the threshold, the gNB 105 may determine the level of frequency selectivity as “low.” This example may be extended to more than one threshold and more than two categories.

[0062] In some embodiments, the gNB 105 may determine a coherence bandwidth of the SRS received from the UE 102. The gNB 105 may determine the level of frequency selectivity' based on a predetermined mapping between the level of frequency selectivity and the coherence bandwidth, wherein the level of frequency selectivity is higher for lower values of the coherence bandwidth and is lower for higher values of the coherence bandwidth.

[0063] In some embodiments, the gNB 105 may compare the coherence bandwidth to one or more thresholds to determine the level of frequency selectivity'. For instance, if the coherence bandwidth is greater than or equal to a threshold, the gNB 105 may determine the level of frequency selectivity' as“low'.” If the coherence bandwidth is less than the threshold, the gNB 105 may determine the level of frequency selectivity' as“high.” This example may be extended to more than one threshold and more than two categories.

[0064] At operation 830, the gNB 105 may receive signal quality measurements. At operation 835, the gNB 105 may determine a variance of the signal quality measurements. In some embodiments, the gNB 105 may receive the signal quality measurements from the UE 102, although the scope of embodiments is not limited in this respect.

[0065] Non-limiting examples of the signal quality' measurements include reference signal receive power (RSRP), layer- 1 RSRP (Ll-RSRP), signal -to-noise ratio (SNR); and/or other. In some embodiments, the signal quality measurements may be per-subband signal quality measurements for a plurality of subbands, although the scope of embodiments is not limited in this respect.

[0066] Embodiments are not limited to determination of the variance of the signal quality measurements. In some embodiments, the gNB 105 may determine other infonnaiion/parameter(s) related to the signal quality measurements, such as an average, a histogram and/or other.

[QQ67] In a non-limiting example, the gNB 105 may compare the variance to one or more thresholds to determine the level of frequency selectivity. For instance, if the variance is greater than or equal to a threshold, the gNB 105 may determine the level of frequency selectivity as“high” If the variance is less than the threshold, the gNB 105 may determine the level of frequency selectivity as “low.” This example may be extended to more than one threshold and more than two categories.

[0068] It should be noted that embodiments are not limited to determination of a category (such as high, low and/or other) of the level of frequency selectivity based on parameters such as delay spread, coherence bandwidth, variance of signal quality measurements and/or other. In some embodiments, the gNB 105 may compare the delay spread, coherence bandwidth, variance and/or other parameter(s) to one or more thresholds. The gNB 105 may use the result for determination of the RLM CSI-RS frequency density and/or other operation(s). For instance, the gNB 105 may: if the delay spread is greater than or equal to a threshold, determine that a first value of RLM CSI-RS frequency density is used; otherwise determine that a second value of RLM CSI-RS frequency density is used.

[0069] At operation 840, the gNB 105 may determine a frequency density ⁷ of CSI-RS to be configured for the CSI-RS resource set allocated for RLM It should be noted that this frequency density may be referred to herein for clarity as an“RLM CSI-RS frequency density ⁷ ” in some cases, but it is understood that such references are not limiting. One or more of the techniques, operations and/or methods described herein may refer to the RLM CSI-RS frequency density ⁷ , but it is understood that one or more of those techniques, operations and/or methods may be applicable to one or more of: CSI-RS; CSI-RS for the CSI resource set allocated for RLM; and/or other.

[0070] In some embodiments, the gNB 105 may determine the RLM CSI- RS frequency density based on the level of frequency selectivity in the downlink. In some embodiments, the gNB 105 may determine the RLM CSI-RS frequency density to be: higher for higher levels of frequency selectivity in the downlink, and lower for lower levels of frequency selectivity in the downlink. For instance, the gNB 105 may determine the RLM CSI-RS in accordance with a non-decreasing relationship between the RLM CSI-RS frequency density and the level of frequency selectivity.

[0071] In a non-limiting example, the gNB 105 may determine the RLM

CSI-RS frequency density as: one RE per RB if the level of frequency selectivity in the downlink is less than a threshold, and three REs per RB if the level of frequency selectivity in the downlink is greater than or equal to the threshold. Embodiments are not limited to usage of these values of the den sity (one RE per RB, three REs per RB), as other values may be used in some embodiments. Embodiments are also not limited to usage of two values, as more than two values may be used in some embodiments.

[0072] In some embodiments, the gNB 105 may receive, from the UE 102, a UE capability message that indicates information related to supported RLM CSI- RS frequency densities (examples of which are given below). The gNB 105 may use this information and/or other information (such as the level of frequency selectivity, delay spread, coherence bandwidth, variance of signal quality

measurements and/or other) to determine the RLM CSI-RS frequency density to be configured for the UE 102, in some embodiments.

[0073] In some embodiments, the UE capability message may indicate a minimum supported RLM CSI-RS frequency density for the CSI-RS resource set allocated for RLM. The gNB 105 may determine the RLM CSI-RS frequency density based on one or more of: the minimum supported RLM CSI-RS frequency density indicated in the UE capability message; additional information (including but not limited to the level of frequency selectivity, delay spread, coherence bandwidth, variance of signal quality measurements and/or other); and/or other. In a non-limiting example, the gNB 105 may determine the RLM CSI-RS frequency density to be greater than or equal to the minimum supported RLM CSI-RS frequency density indicated in the UE capability message. In another non-limiting example, the gNB 105 may use additional information (including but not limited to the level of frequency selectivity, delay spread, coherence bandwidth, variance of signal quality measurements and/or other) to determine an RLM CS1-RS frequency density, and may ensure that the RLM CSI-RS frequency density is at least greater than or equal to the minimum supported RLM CSI-RS frequency density indicated in the UE capability message.

[0074] In some embodiments, the UE capability message may indicate a plurality of minimum supported RLM CSI-RS frequency densities corresponding to a plurality of candidate sub-carrier spacings (SCSs). The gNB 105 may determine the RLM CSI-RS frequency density based on one or more of: the minimum supported RLM CSI-RS frequency density corresponding to an SCS used by the gNB 105 to communicate with the UE 102; additional information (including but not limited to the level of frequency selectivity, delay spread, coherence bandwidth, variance of signal quality measurements and/or other); and/or other. In some embodiments, a technique similar to the technique described above (usage of the additional information to determine an RLM CSI-RS frequency density, and ensuring that the RLM CSI-RS frequency density is at least greater than or equal to a minimum supported RLM CSI-RS frequency density) may be used, wherein the minimum supported RLM CSI-RS frequency density corresponds to the SCS used by the gNB 105 to communicate with the UE 102,

[0075] In some embodiments, the UE capability message may indicate a plurality of minimum supported RLM CSI-RS frequency densities corresponding to a plurality of candidate carrier frequencies. The gNB 105 may determine the RLM CSI-RS frequency density based on one or more of: the minimum supported RLM CSI-RS frequency density' corresponding to a carrier frequency on which the gNB 105 communicates with the UE 102; additional information (including but not limited to the level of frequency selectivity', delay spread, coherence bandwidth, variance of signal quality measurements and/or other); and/or other. In some embodiments, a technique similar to the technique described above (usage of the additional information to determine an RLM CSI-RS frequency density, and ensuring that the RLM CSI-RS frequency density' is at least greater than or equal to a minimum supported RLM CSI-RS frequency density) may be used, wherein the minimum supported RLM CSI-RS frequency density corresponds to the carrier frequency on winch the gNB 105 communicates with the UE 102. [0076] At operation 845, the gNB 105 may transmit control signaling that indicates the RLM CSI-RS frequency density. In some embodiments, the gNB 105 may transmit the control signaling to the UE 102, although the scope of

embodiments is not limited m this respect.

[0077] At operation 850, the gNB 105 may encode CSI-RS of the CSI-RS resource set allocated for RLM. In some embodiments, the gNB 105 may encode the CSI-RS in accordance with the RLM CSI-RS frequency density. In some embodiments, the gNB 105 may encode the CSI-RS based on the RLM CSI-RS frequency density'. In some embodiments, the gNB 105 may encode the CSI-RS for transmission. In some embodiments, the gNB 105 may encode the CSI-RS for transmission to the UE 102, although the scope of embodiments is not limited in this respect.

[0078] At operation 905, the UE 102 may exchange control signaling with the gNB 105. The control signaling of operation 905 may be the same as, similar to and/or related to the control signaling of operation 805, although the scope of embodiments is not limited in this respect.

[0079] At operation 910, the UE 102 may transmit the SRS. At operation

915, the UE 102 may determine signal quality measurements. At operation 920, the UE 102 may transmit additional control signaling that indicates the signal quality measurements. At operation 925, the UE 102 may receive control signaling (from the gNB 105 and/or other component) that indicates the RLM CSI-RS frequency density. At operation 930, the UE 102 may receive CSI-RS for RLM. At operation 935, the UE 102 may determine a block error rate (BLER) based on the CSI-RS resources for RLM.

[0080] In some embodiments, the UE 102 may receive first control signaling from the gNB 105. The first control signaling may configure the UE 102 with a plurality of CSI-RS resource sets in the downlink, wherein each CSI-RS resource set includes a plurality of CSI-RS resources, wherein one of the CSI-RS resource sets is allocated for RLM at the UE 102. The UE 102 may transmit, to the gNB 105, a UE capability message that indicates a minimum supported RLM CSI- RS frequency density for the CSI-RS resource set allocated for RLM. The UE 102 may receive, from the gNB 105, second control signaling that indicates an RLM CSI-RS frequency density' to be configured for the CSI-RS resource set allocated for RLM. The UE 102 may receive, in accordance with the RLM CSI-RS frequency density indicated in the second control signaling, CSI-RS of the CSI-RS resource set allocated for RLM.

[0081] It should be noted that references to the terms“first control signaling” and“second control signaling” may be used for clarity, but such references are not limiting. In some embodiments, the UE 102 may receive the first control signaling before the second control signaling, although the scope of embodiments is not limited in this respect.

[0082] In some embodiments, the first control signaling may further configure the UE 102 with a set of SRS resources in the uplink. The UE 102 may receive an SRS-SpatialRelationlnfo field in the first control signaling. In some embodiments, the SRS-SpatialRelationlnfo field may include information identifying a spatial relationship between: one or more downlink beams mapped to the CSI-RS resource set allocated for RLM; and one or more uplink beams mapped to the set of SRS resources. The UE 102 may transmit the SRS in accordance with the one or more uplink beams indicated in the SRS-SpatialRelationlnfo field.

[0083] In some embodiments, the first control signaling may further indicate a plurality of subbands for which the UE, 102 is to perform per-subband signal quality measurements. The UE 102 may determine the signal quality measurements. The UE 102 may transmit additional control signaling that indicates the signal quality measurements.

[QQ84] In some embodiments, the UE 102 may encode the UE capability message to indicate an index of a plurality of candidate indexes, each of the candidate indexes mapped to: a sub-carrier spacing (SCS) of a plurality of candidate SCSs, and a carrier frequency of a plurality of candidate carrier frequencies. In a non-limiting example, the UE 102 may encode the UE capability message to one or more of: a first value to indicate that the UE 102 supports an RLM CSI-RS frequency density of one RE per RB and that the UE 102 does not support an RLM CSI-RS frequency density of three REs per RB; a second value to indicate that the UE 102 supports an RLM CSI-RS frequency density of three REs per RB and that the UE 102 does not support an RLM CSI-RS frequency density of one RE per RB; a third value to indicate that the UE 102 supports an RLM CSI-RS frequency density of three REs per RB and that the UE 102 supports an RLM CSI-RS frequency density of one RE per RB; and/or other. Embodiments are not limited to the number of values described above, and are also not limited to the cases described above. Other values of the RLM CSI-RS frequency densities and other combinations (of support and non-support) may be used, m some embodiments. ] 0085] In some embodiments, the UE 102 may encode the UE capability message to indicate one or more of: a plurality of minimu supported RLM CSI-RS frequency densities corresponding to a plurality of candidate sub-carrier spacings (SCSs); a plurality of minimum supported RLM CSI-RS frequency densities corresponding to a plurality ⁷ of carrier frequencies; and/or other.

[0086] The Abstract is provided to comply with 37 C.F.R. Section 1.72(b) requiring an abstract that will allow the reader to ascertain the nature and gist of the technical disclosure. It is submitted with the understanding that it will not be used to limit or interpret the scope or meaning of the claims. The following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate embodiment.