Patent Description:
The present invention is related to 3GPP new radio (NR) physical layer design. More specifically, the focus is on NR operation in the cm-Wave and mm-Wave bands, in general, bands above <NUM>. A typical characteristic for cm-Wave and mm-Wave operation is a beam-based access, where both a gNB and a UE operate using narrower transmit and receive beams than sector-wide and omni-directional beams, respectively, due to a high-array gain required to compensate for higher path loss, but also because of technological constraints favoring distributed power amplifier (PA) architectures.

The use of narrow beams at both ends of the links between the gNB and the UE improves the link budget, but, as a consequence, the links are more sensitive to blocking and, thus, specific procedures and methods are needed to enable fast realignment or reestablishment of a beam pair between the gNB and the UE. One of the most important procedures of this type is beam recovery - a procedure in which a beam failure is detected and a new beam pair link is established without any need to declare a radio link failure. In the following, the current state of the art related to beam recovery is reviewed.

The network can configure the UE with a set of reference signals (RS) for monitoring the quality of a link. The set of reference signals may be referred as q0 or beam failure detection reference signals (BFD-RS). Typically, BFD-RSs are configured to be spatially quasi collocated (QCL'd) with physical downlink control channel (PDCCH) demodulation reference signals (DMRS), that is, these reference signals correspond to downlink beams used to transmit PDCCH. Downlink beams are identified by a reference signal, either synchronization signal physical broadcast channel (SS/PBCH or SSB) block index or channel state information reference signal (CSI-RS) resource index. SS/PBCH block may comprise of synchronization signals such as PSS and SSS (primary, secondary synchronization signals) and PBCH (Physical Broadcast Channel) including PBCH-DMRS (demodulation reference signals). The network may configure the beam failure detection reference signal (BFD-RS) list using radio resource control (RRC) signaling or it may be possible to define a way to use combined RRC + medium access control (MAC) control element (CE) signaling, where specific RRC configured signals are activated using a MAC CE. When the UE is not explicitly configured with a BFD-RS list, it determines the BFD-RS resources implicitly based on the configured, indicated, or activated PDCCH transmission configuration indication (TCI) states per CORESET (Control Resource Set, set of physical resources used to transmit downlink control channel), that is, the downlink reference signals (CSI-RS, SS/PBCH block) which are QCL'd with PDCCH DMRS, or, in other words, PDCCH beams. In general, when two different signals share the same QCL type, they share the same indicated properties. As an example, the QCL properties may be, for example, delay spread, average delay, Doppler spread, Doppler shift, spatial RX. QCL type A means Doppler spread, Doppler shift, delay spread, and/or average delay, and QCL type D means spatial RX. As an example the current TS <NUM> lists following QCL types:.

As a further example if a CSI-RS and SSB have the type D QCL assumption between each other, it means that UE may utilize same RX spatial filter (beam) to receive these signals.

The physical layer periodically assesses the quality of the radio link based on BFD-RS in the set of q0. Typically, the whole set of q0 is evaluated but the link quality evaluation may also be limited to RS that are QCL'd with PDCCH DMRS. Assessment is done per BFD-RS and, when the radio link condition of each BFD-RS in the beam failure detection set is considered to be in failure condition, that is, the hypothetical PDCCH block error rate (BLER) estimated using the RS is above a configured threshold, a beam failure instance (BFI) indication is provided to a higher layer (MAC). One example of a BLER threshold value may be the out-of-sync (OOS) threshold used for radio link monitoring OOS/Qout = <NUM>%. Evaluation and indication is done periodically. In case the at least one BFD-RS is not in failure condition, no indication is provided to the higher layer.

The MAC layer implements a counter to count the BFI indications from the physical layer (PHY), and, if the BFI counter reaches a maximum value configured by the network, a beam failure is declared. The counter can be configured to be supervised by a timer: each time MAC receives a BFI indication from a lower layer, a timer is started. Once the timer expires, the BFI counter is reset; that is to say, the counter value is set to zero.

The network may provide the UE with a list of candidate RSs for recovery that can be indicated using dedicated signals. Candidate beam Layer <NUM>-reference signal received power (L1-RSRP) measurements may be provided to the MAC layer, which performs the selection of a new candidate and determines the uplink resources to indicate the new candidate to the network. The network may configure the UE with dedicated signaling resources, such as physical random access channel (PRACH) resources, that are candidate beam specific; that is, the UE can indicate the new candidate by sending a preamble. This set of candidate beams or reference signals corresponding to candidate beams may be referred to as set of q1.

A beam failure recovery procedure is initiated when the UE has declared beam failure and has detected a new candidate beam or beams based on physical layer measurements, such as L1-RSRP measurements on downlink reference signals (CSI-RS/SSB). A dedicated signal, such as one from the PRACH pool, which can be referred to as a BFR resource or contention-free random access (CFRA) resource, although it has to be noted that the beam recovery procedure differs slightly from a random access (RA) procedure when it comes to the gNB response to preamble reception, is configured per candidate RS in the Candidate-Beam-RS-List (q1). A specific threshold may be configured so that, when any of the new candidates, based on L1-RSRP measurements, are above the threshold, they can be indicated using a dedicated signal (set of resources in set q1). The UE selects a candidate beam from that set and, in case there are no beams above the configured threshold, the UE utilizes contention-based signaling to indicate the new candidate, where contention-based random access (CBRA) preamble resources are mapped to specific downlink RSs.

The UE monitors network response to BFRR/BFRQ (Beam Failure Recovery Request), during the beam recovery response window, which is similar to a random access response (RAR) window, using the same beam alignment, that is, the same beam direction that was used for the transmitter (TX) is used for the receiver (RX), for transmitting the recovery signal; it expects the network to provide the response using a beam that is spatially QCL'd with the indicated downlink reference signal. A case where this correspondence does not hold is not yet defined.

In case of contention-free signaling used for beam recovery purposes, the UE expects the network to respond to the UE using a cell radio network temporary identifier (C-RNTI) instead of random access radio network temporary identifier (RA-RNTI) when a contention-free random access (CFRA) procedure is used. For CFRA BFR, the UE monitors PDCCH (for C-RNTI and specific DCI format) based on a dedicated search space configuration. This is referred as search-space-BFR. Search space configuration determines, for example, the PDCCH monitoring pattern for the associated CORESET. Search-space-BFR is only monitored during the network/gNB response window, after transmission of CFRA for BFR. In case CBRA resources are used for beam failure recovery, the UE currently expects a response as it normally does in the RA procedure. CBRA procedure currently does not explicitly indicate that the RA procedure is for beam failure recovery (it may be determined by the network, for example, based on UE ID); it may be possible to define signaling to indicate BFRR during CBRA procedure. This may also alter the CBRA recovery procedure, for example, in terms of network response to BFRR.

In downlink, a so-called TCI framework is defined to provide information about the TX beams to be used, and correspondingly assist the UE to set its receive beam properly when receiving the downlink transmission. The UE may be configured with one or multiple TCI states, where each TCI state at above <NUM> has an associated reference signal which provides a quasi co-location type D (QCL Type-D) parameter. QCL type-D is defined to provide the spatial domain characteristics of the RS. The associated reference signal can be SS/PBCH block or CSI-RS. For PDCCH, the UE can have one active TCI state per CORESET - the UE can be configured for up to <NUM> CORESETs - and, for PDSCH, the UE may have up to eight (<NUM>) active TCI states representing eight (<NUM>) candidate beams from which the gNB can select one dynamically via downlink control information (DCI) for the scheduled DL transmission. Different TCI states may represent TX beams of different transmission/reception points (TRPs) of the cell.

However, a problem scenario is illustrated schematically in <FIG>, where UE <NUM> is in the coverage area of three transmission/reception points <NUM>, <NUM>, <NUM> of the same cell. The transmission points <NUM>, <NUM>, <NUM> may alternatively belong to different cells. The UE <NUM> has one DL beam pair link <NUM>, <NUM>, <NUM> to each of the transmission/reception points <NUM>, <NUM>, <NUM>, but only one UL link <NUM> toward transmission/reception point <NUM>. As far as the uplink is concerned, this is the typical case since, even though the UE can be configured for multiple physical uplink control channel (PUCCH) resources, the spatial relation information configured for them, that is, a transmit beam, is the same. That is because the multiple PUCCH resources are defined to enable flexibility for PUCCH resource allocation, but not for enabling use of multi-beam PUCCH.

Currently, in new radio (NR), beam failure detection and recovery only considers downlink failure, that is, the PDCCH failure; uplink failure is not explicitly determined. In addition, in NR, determining the indication of a beam failure instance to a higher layer by L1 requires all the BFD-RS (in the set of q0) to be in failure condition, and, thus, the UL direction is not considered explicitly, and, thus, no signaling or mechanism is specified. Also, the partial beam failure, where only subsets of BFD-RS are in failure condition, is not considered in current NR specifications.

In the example scenario shown in <FIG>, when the link toward TRP#B <NUM> fails, that is, when both the DL link <NUM> and the UL link <NUM> fail, the UE does not trigger any beam failure recovery, since the other links are considered not to be in failure. In case the
failed link would have been, for example, TRP#A <NUM>, the UE <NUM> could indicate the partial link failure using UL signaling on the UL link <NUM>. However, since link B has the only UL link <NUM> configured for the UE <NUM>, the failure should be declared and recovery procedure initiated.

Uplink beam failure, in case of link reciprocity, may be determined by UE <NUM> by determining the link quality on DL RS (SSB/CSI-RS).

This problem scenario is not considered in either 3GPP TS <NUM> or 3GPP TS <NUM>.

In addition, as illustrated in <FIG>, certain (DL) RS beams <NUM>, <NUM> could be blocked by the body of a person with the UE <NUM> between the TX and corresponding (UE) RX beam. Depending on the propagation conditions, these beams could still have good observed RSRP, even assuming a loss of 3dB in the body, resulting in a low path-loss (PL) estimate. Because the UE requires additional MPR (Maximum Power Reduction), P-MPR (Power Management Maximum Power Reduction), to meet emission-related requirements, such as electromagnetic energy absorption requirements, the actual achievable PL for a given UL resource allocation will be reduced compared to the level that could be estimated based on the DL RSRP. This could, together with the body loss, result in failure in UL beam <NUM>.

It should be understood, both above and in the discussion to follow, that the term "gNB" should be understood to mean "network node". The term "gNB" is used to denote a network node in <NUM>. However, it should be understood that the present invention, as described below, is not limited to <NUM>, but may be applicable to other generations yet to be developed. As a consequence, "gNB" should be understood more broadly as a network node. R1-<NUM> by Huawei, HiSilicon, is a contribution on beam failure recovery. It proposes that a UE can be configured, for a serving cell, with a set q<NUM> of periodic CSI-RS resource configuration indexes by higher layer parameter Beam-Failure-Detection-RS-ResourceConfig and with a set q<NUM> of CSI-RS resource configuration indexes and/or SS/PBCH block indexes by higher layer parameter Candidate-Beam-RS-List for radio link quality measurements on the serving cell. Each periodic CSI-RS resources that is one-to-one mapped to each CORESET within the set q<NUM> has the same spatial QCL assumption with the TCI state of corresponding CORESET.

In a first aspect of the present invention, a method according to claim <NUM> is provided.

In a second aspect of the present invention, an apparatus according to claim <NUM> is provided.

The foregoing and other aspects of these teachings are made more evident in the following detailed description, when read in conjunction with the attached drawing figures.

The present invention is directed toward methods and procedures for uplink beam failure detection and recovery.

In accordance with the present invention, the network, specifically a gNB, configures a contention-free/dedicated signal for indicating uplink beam failure recovery. The CFRA signal corresponds to at least one link with downlink only, that is, an active TCI state for PDCCH or PDSCH.

The transmission of the CFRA signal by the UE indicates to the network (gNB) both the UL failure and the new UL candidate that corresponds to the TCI state, that is, reference signal, for PDCCH or a reference signal with a spatial QCL-type D parameter of the TCI state activated for the PDCCH reception. Alternatively, the gNB itself can detect that the UL has failed.

The TCI state activated for the PDCCH reception, whose reference signal is not used for PUCCH as spatial relation information, comprising a reference signal to determine UL TX beam (the same DL RS is used as spatial source RS), may be mapped with an associated UL recovery link. In one alternative, the TCI state for PDCCH (or the reference signal) may be used as spatial relation information for PUSCH transmission but not for PUCCH, thus only the data channel is mapped to such uplink. This may also be one criteria to prioritize which existing link is considered to be new candidate UL beam (such as for control channel transmission) by a UE. In one example, when a UE determines that uplink beam failure has occurred, and it evaluates the links it can indicate with CFRA or CBRA signaling for recovery, it may prioritize links that have PUSCH mapped. Link selection may also take into account other parameters such as the DL RS quality (RSRP, RSRQ, SINR, hypothetical PDCCH BLER) associated with the dedicated CFRA signal or CBRA. CFRA and/or CBRA signals may be mapped to CSI-RS and/or SSB signals. Multiple metrics may be used in conjunction to evaluate, such as RSRP and SINR/BLER. As an example, first the candidates are evaluated based on RSRP, and the best candidates are estimated with a BLER-based metric. Also, UL power reduction may be taken into account. In one example, it may be possible to utilize similar TCI state framework, as used for PDCCH/PDSCH, for indicating QCL association of PUCCH/PUSCH DMRS to specific downlink RS (SSB, CSI-RS); thus, the TCI state would indicate PUCCH and/or PUSCH beam. Also, in TCI-based beam indication (uplink or downlink), for example, a specific signal, such as SSB, may not be directly indicated as TCI state for PDCCH, but it may be indicated through TRS (tracking reference signal) configuration; that is, SSB may be configured as TRS signal and the TRS may be indicated as active TCI state for PDCCH. In a similar manner, a CSI-RS signal may also be indirectly indicated as an active TCI state; that is, CSI-RS is configured as TRS signal, and, in TCI configuration, the TRS is indicated as active TCI state.

To determine UL beam failure, various ways may be used. For recovering downlink beam failure or uplink failure, different triggering conditions may be applied. In an example, if DL failure is determined using the set of q0, the UL failure may be estimated using the set of q0uplink which contains the RS respective to estimating UL beam failure. The failure condition of these sets may be determined independently, and different set signals may be triggered for recovery depending on which set was estimated to be in failure. As an example, specific set of signals (CFRA) can be used for indicating DL beam failure (and also the new candidate beam) and UL. In the UL case, the CFRA signals, as described herein, may be mapped to reference signals corresponding to TCI states for PDCCH or PDSCH (or PUSCH). Failure indication may be configured or specified to be indicated per set of q0 (either q0 or q0uplink) condition. When all the RS in the set are considered to be in failure condition, the indication is provided by L1 to higher layers, such as MAC. MAC layer may run its own failure instance counter for each set (q0 or q0uplink) to determine which type of failure has occurred and which signals to trigger recovery; that is, CFRA for UL recovery can only be triggered when UL beam failure has been declared. In one alternative, it could be enough to trigger (partial) UL failure indication on UL (if UE has multiple UL and one the UL fails) which is not in failure condition.

When the UE declares uplink beam failure, that is, as an example, when all the links that are used for UL (PUCCH and/or PUSCH) are considered to have failed based on measurements on downlink RS indicating that the UL link condition is either below quality threshold or the DL RS is not received/detected, assuming DL/UL beam reciprocity, the UE initiates BFR by sending msg1, which is a CFRA preamble dedicated for UL failure recovery.

In some embodiments, the triggering of awareness of the uplink beam failure could be based solely on an observed level/quality on a downlink RS, such as threshold value for RSRP, signal-to-interference-and-noise ratio (SINR), and power level. In alternative embodiments, the uplink beam failure declaration could alternatively or in addition be based on uplink-related parameters.

In one example, the UL link (for example, based on measurements on DL RS) may be in non-failure condition, when MPR is not taken into account but when the MPR is used in calculating the transmission power available for specific UL direction, UL beam, the link may be considered to be in failure condition. Thus, in this case, the measurement on DL RS alone would not cause the UL link to be in failure condition, but together with transmission power reduction the link is in failure condition. In an aspect of the present invention, the UE may switch between CFRA and CBRA for UL beam recovery. Specifically, in one aspect of the invention, the UE may determine the UL recovery candidates based on the potential emission limits for the UL direction. In case the UE is not required/does not take into account the emission limits, it evaluates the candidates solely based on DL signal quality.

In another aspect of the present invention, the gNB can trigger UL recovery. Specifically, if the gNB determines UL beam failure, such as by not receiving a signal (PUCCH/PUSCH) from the UE, it may trigger UL recovery by a specific PDCCH command.

In general, a CFRA signal may be mapped to a synchronization signal (SS) block or to CSI-RS signals. Transmission of a signal indicates the associated downlink RS to the network. CBRA signals may also be mapped to SSBs or CSI-RS signals. Also, in one example, CSI-RS may be indicated using a CFRA signal, but the preamble signal is associated to SSB (indication is through QCL assumption of CSI-RS and SSB).

In case of partial UL failure, if the UE has another UL link with SR/PUCCH configuration, it may indicate the partial UL failure using a specific MAC CE or PUCCH signaling. In this case, MAC/L1 may indicate whether a specific UL link index, or the corresponding DL RS, is in a failure condition from UL perspective.

In one aspect, the CFRA update for q1uplink (set of dedicated signals for indicating UL beam failure) may be updated by the network when the PDCCH configuration/new PDCCH TCI states are activated. In this manner, the CFRA signal can be configured to correspond to the DL RS of the active TCI state for PDCCH. Alternatively, if the CFRA signal configuration is not updated, it may be mapped in sequence to the existing PDCCH links. That is to say, if a UE has two active TCI states for PDCCH and two CFRA signals are listed in the set and different TCI states are activated, the CFRA signals are mapped to the new active TCI states although there may not be any spatial relation for the DL RS associated with CFRA signal and the active TCI state. Alternatively, the spatial relation is fixed in a manner that the CFRA signal indicates specific candidate for UL recovery although it does not correspond to any active TCI state for PDCCH.

In one implementation aspect, if the DL RS corresponding to PUCCH (or PUSCH) differs from active PDCCH TCI states, the UE may determine to include the downlink RS resource indexes in a set of q0uplink (set of failure detection reference signals for uplink). In another aspect, UE determines implicitly to include the DL RS to the failure detection set of q0uplink based on the PUCCH configuration by the network (UE is configured for the PUCCH with spatial relation information to DL RS). This set is used for UL failure detection. The failure detection set can also be configured explicitly. UE may also determine to include the DL RS corresponding to PUCCH/PUSCH channel implicitly (based on TCI state activation or when PUCCH beam is determined based on the indicated spatial relation to specific DL RS) to either the q0 or q0uplink. That is, the uplink specific DL RS may be part of the beam failure set q0, in this case the DL and UL beams are not differentiated in the failure detection or they may have separate sets, named as an example q0 and q0uplink. Alternatively or additionally, UE may be configured with any two or more sets for failure detection where the failure detection is determined per set of failure detection reference signals.

A different procedure (different signals or indications) may apply when either q0 (PDCCH links) or q0uplink (PUCCH or PUSCH) links are in failure.

Reference is now made to <FIG> for illustrating a simplified block diagram of various electronic devices and apparatus that are suitable for use in practicing an exemplary embodiment of the present invention. In <FIG>, a wireless network <NUM> is adapted for communication over a wireless link <NUM> with an apparatus, such as a mobile communication device, which is referred to as a UE <NUM>, via a wireless network access node, such as a base station or relay station or remote radio head, and more specifically shown as a gNodeB (gNB) <NUM>. The network <NUM> may include a network element <NUM>, which serves as a gateway to a broader network, such as a public switched telephone/data network and/or the Internet.

The UE <NUM> includes a controller, such as a computer or a data processor (DP) 310A, a computer-readable memory medium embodied as a memory (MEM) 310B, which stores a program of computer instructions (PROG) 310C, and a suitable radio frequency (RF) transmitter and receiver 310D for bi-directional wireless communications with the gNodeB (gNB) <NUM> via one or more antennas. The gNodeB <NUM> also includes a controller, such as a computer or a data processor (DP) 312A, a computer-readable memory medium embodied as a memory (MEM) 312B that stores a program of computer instructions (PROG) 312C, and a suitable RF transmitter and receiver 312D for communication with the UE <NUM> via one or more antennas. The gNodeB <NUM> is coupled via a data/control path <NUM> to the network element <NUM>. The path <NUM> may be implemented as an S1 interface when the network <NUM> is an LTE network. The gNodeB <NUM> may also be coupled to another gNodeB or to an eNodeB via data/control path <NUM>, which may be implemented as an X2 interface when the network <NUM> is an LTE network.

At least one of the PROGs 310C and 312C is assumed to include program instructions that, when executed by the associated DP, enable the device to operate in accordance with the exemplary embodiments of this invention. That is, the exemplary embodiments of this invention may be implemented at least in part by computer software executable by the DP 310A of the UE <NUM> and/or by the DP 312A of the gNodeB <NUM>, or by hardware, or by a combination of software and hardware (and firmware).

In general, the various embodiments of the UE <NUM> can include, but are not limited to, cellular telephones; personal digital assistants (PDAs) having wireless communication capabilities; portable computers having wireless communication capabilities; image capture devices, such as digital cameras, having wireless communication capabilities; gaming devices having wireless communication capabilities; music storage and playback appliances having wireless communication capabilities; and Internet appliances permitting wireless Internet access and browsing, as well as portable units or terminals that incorporate combinations of such functions.

The computer-readable MEMs 310B and 312B may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic-memory devices and systems, optical-memory devices and systems, fixed memory and removable memory. The DPs 310A and 312A may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multicore processor architecture, as non-limiting examples.

It should be noted that the various DPs 310A, 312A may be implemented as one or more processors/chips, either or both of the UE <NUM> and the gNodeB <NUM> may include more than one transmitter and/or receiver 310D, 312D, and particularly the gNodeB <NUM> may have its antennas mounted remotely from the other components of the gNodeB <NUM>, such as for example tower-mounted antennas.

Reference is now made to <FIG> for illustrating a simplified block diagram of various electronic devices and apparatus that are suitable for use in practicing another exemplary embodiment of the present invention. In the following, different exemplifying embodiments will be described using, as an example of an access architecture to which the embodiments may be applied, a radio access architecture based on long term evolution advanced (LTE Advanced, LTE-A) or new radio (NR, <NUM>), without restricting the embodiments to such an architecture, however. It is obvious for a person skilled in the art that the embodiments may also be applied to other kinds of communications networks having suitable means by adjusting parameters and procedures appropriately. Some examples of other options for suitable systems are the universal mobile telecommunications system (UMTS) radio access network (UTRAN or E-UTRAN), long term evolution (LTE, the same as E-UTRA), wireless local area network (WLAN or WiFi), worldwide interoperability for microwave access (WiMAX), Bluetooth®, personal communications services (PCS), ZigBee®, wideband code division multiple access (WCDMA), systems using ultra-wideband (UWB) technology, sensor networks, mobile ad-hoc networks (MANETs), and Internet Protocol multimedia subsystems (IMS) or any combination thereof.

The embodiments are not, however, restricted to the system given as an example, but a person skilled in the art may apply the solution to other communication systems provided with necessary properties.

<FIG> shows user devices <NUM> and <NUM> configured to be in a wireless connection on one or more communication channels in a cell with an access node (such as (e/g)NodeB) <NUM> providing the cell. The physical link from a user device to a/an (e/g)NodeB is called uplink or reverse link and the physical link from the (e/g)NodeB to the user device is called downlink or forward link. It should be appreciated that (e/g)NodeBs or their functionalities may be implemented by using any node, host, server, or access point, etc., entity suitable for such a usage.

A communications system typically comprises more than one (e/g)NodeB in which case the (e/g)NodeBs may also be configured to communicate with one another over links, wired or wireless, designed for the purpose. These links may be used for signaling purposes. The (e/g)NodeB is a computing device configured to control the radio resources of communication system to which it is coupled. The NodeB may also be referred to as a base station, an access point, or any other type of interfacing device including a relay station capable of operating in a wireless environment. The (e/g)NodeB includes or is coupled to transceivers. From the transceivers of the (e/g)NodeB, a connection is provided to an antenna unit that establishes bi-directional radio links to user devices. The antenna unit may comprise a plurality of antennas or antenna elements. The (e/g)NodeB is further connected to core network <NUM> (CN or next generation core NGC). Depending on the system, the counterpart on the CN side can be a serving gateway (S-GW, routing and forwarding user data packets), packet data network gateway (P-GW), for providing connectivity of user devices (UEs) to external packet data networks, or mobile management entity (MME), etc..

A user device may also be a device having capability to operate in an Internet of Things (IoT) network which is a scenario in which objects are provided with the ability to transfer data over a network without requiring human-to-human or human-to-computer interaction.

It should be understood that, in <FIG>, user devices may include two antennas. The number of reception and/or transmission antennas may naturally vary according to a current implementation.

<NUM> enables the use of multiple input-multiple output (MIMO) antennas, many more base stations or nodes than the LTE (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. <NUM> mobile communications supports 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. <NUM> is expected to have multiple radio interfaces, namely below <NUM>, cm-Wave and mm-Wave, and also being integrable with existing legacy radio access technologies, such as the LTE. Integration with the LTE may be implemented, at least in the early phase, as a system, where macro coverage is provided by the LTE and <NUM> radio interface access comes from small cells by aggregation to the LTE. In other words, <NUM> is planned to support both inter-RAT operability (such as LTE-<NUM>) and inter-RI operability (inter-radio interface operability, such as below <NUM> - cm-Wave, below <NUM> - cm-Wave - mm-Wave). One of the concepts considered to be used in <NUM> networks is network slicing in which multiple independent and dedicated virtual sub-networks (network instances) may be created within the same infrastructure to run services that have different requirements on latency, reliability, throughput and mobility.

Edge computing covers a wide range of technologies, such as wireless sensor networks, mobile data acquisition, mobile signature analysis, cooperative distributed peer-to-peer ad hoc networking and processing also classifiable as local cloud/fog computing and grid/mesh computing, dew computing, mobile edge computing, cloudlet, distributed data storage and retrieval, autonomic self-healing networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (massive connectivity and/or latency critical), critical communications (autonomous vehicles, traffic safety, real-time analytics, time-critical control, healthcare applications).

The 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> by "cloud" <NUM>). The communication system may also comprise a central control entity, or the like, providing facilities for networks of different operators to cooperate, for example, in spectrum sharing.

It should also be understood that the distribution of labor between core network operations and base station operations may differ from that of the LTE or even be non-existent.

<NUM> may also utilize satellite communication to enhance or complement the coverage of <NUM> service, for example, by providing backhauling. Satellite communication may utilize geostationary earth orbit (GEO) satellite systems, but also low earth orbit (LEO) satellite systems, in particular mega-constellations (systems in which hundreds of (nano)satellites are deployed).

It is obvious for a person skilled in the art that the depicted system is only an example of a part of a radio access system and in practice, the system may comprise a plurality of (e/g)NodeBs, the user device may have an access to a plurality of radio cells and the system may also comprise other apparatuses, such as physical layer relay nodes or other network elements, etc. At least one of the (e/g)NodeBs may be a Home (e/g)nodeB. Additionally, in a geographical area of a radio communication system, a plurality of different kinds of radio cells as well as a plurality of radio cells may be provided.

An HNB Gateway (HNB-GW), which is typically installed within an operator's network may aggregate traffic from a large number of HNBs back to a core network.

<FIG> is a flow chart illustrating a method performed by a user equipment in accordance with the present disclosure. In block <NUM>, the user equipment determines whether a downlink beam signal is being received from a base station. In block <NUM>, the user equipment determines whether a measurable property of the downlink beam signal does not meet a preselected threshold when the downlink beam signal is being received from the base station. In block <NUM>, the user equipment transmits a message to the base station indicating that at least one uplink beam corresponding to the downlink beam has failed, when the downlink beam signal is not being received from the base station or when the measurable property of the downlink beam signal does not meet the preselected threshold. In block <NUM>, the user equipment receives a reply message from the base station with information required to determine a new uplink beam.

<FIG> is a flow chart illustrating a method performed by a base station in accordance with the present disclosure. In block <NUM>, the base station determines whether at least one uplink beam signal is being received from a user equipment. In block <NUM>, the base station determines whether a measurable property of the at least one uplink beam signal does not meet a preselected threshold, when the at least one uplink beam signal is being received from the user equipment. In block <NUM>, the base station transmits a message to the user equipment to initiate uplink beam recovery, when at least one uplink beam signal is not being received from the user equipment or when the measurable property of the at least one uplink beam signal does not meet the preselected threshold.

For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software, which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto.

While various aspects of the exemplary embodiments of this invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

It should thus be appreciated that at least some aspects of the exemplary embodiments of the inventions may be practiced in various components, such as integrated circuit chips and modules, and that the exemplary embodiments of this invention may be realized in an apparatus that is embodied as an integrated circuit. The integrated circuit, or circuits, may comprise circuitry, as well as possibly firmware, for embodying at least one or more of a data processor or data processors, a digital signal processor or processors, baseband circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments of this invention.

Various modifications and adaptations to the foregoing exemplary embodiments of this invention may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. For example, while the exemplary embodiments have been described above in the context of advancements to the <NUM> NR system, it should be appreciated that the exemplary embodiments of this invention are not limited for use with only this one particular type of wireless communication system. The following abbreviations have been used in the preceding discussion:.

The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.

Various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. However, any and all modifications of the teachings of this disclosure will still fall within the scope of the appended claims.

Claim 1:
A method comprising:
determining (<NUM>) whether a downlink beam signal is being received from a base station;
when the downlink beam signal is being received from the base station, determining (<NUM>) whether a measurable property of the downlink beam signal does not meet a preselected threshold;
when the downlink beam signal is not being received from the base station or when the measurable property of the downlink beam signal does not meet the preselected threshold, transmitting (<NUM>) a message to the base station, the message being a contention-free random access, CFRA, preamble signal, wherein the message indicates that at least one uplink beam corresponding to the downlink beam has failed and a new uplink beam candidate.