CN116896403A - Information sharing for beam management in a repeater - Google Patents

Abstract

A method of determining an access link beam by a repeater is disclosed, comprising: an indication of a beam index is received from the base station, the beam index comprising the indicated beam and a corresponding time at which the indicated beam was applied, and at least one set of resources is transmitted using the indicated beam.

Description

Information sharing for beam management in a repeater

The present application claims priority benefits from U.S. provisional applications nos. 63/329,724, 63/392,922 and 63/444,698, filed on, respectively, month 11 of 2022, month 28 of 2022, and month 10 of 2023, the disclosures of which are incorporated herein by reference in their entireties as if fully set forth herein.

Technical Field

The present disclosure relates generally to wireless communication systems. More particularly, the subject matter disclosed herein relates to improvements in beam management in a repeater in a wireless communication system.

Disclosure of Invention

In a conventional New Radio (NR), downlink (DL) beam management can be implemented in three steps, which are commonly referred to as P1, P2 and P3, although such a flag is not used in this specification.

Coarse beam training occurs in a P1 procedure, which is typically an initial access phase in which a next generation NodeB (gNB) scans a set of Synchronization Signal Block (SSB) bursts, and based on the selected SSB, a User Equipment (UE) transmits a Physical Random Access Channel (PRACH) using a preamble/occasion associated with the selected SSB. Once the gcb receives the transmitted PRACH, the gcb knows the preferred beam to use in the subsequent DL transmission.

During P2, once the UE is in a Radio Resource Control (RRC) connected state, the gNB can further fine tune the DL beam. In this step, the gNB transmits a plurality of narrow beams for reporting its quality by reporting the L1-Reference Signal Received Power (RSRP) of the best beam and the differential RSRP of the other beams with respect to the best beam. Once the gcb receives the transmitted report from the UE, the gcb can infer the preferred DL beam at the UE.

During P3, the gNB allows the UE to fine tune its receive beam. This is achieved by transmitting multiple channel state information-reference signals (CSI-RS) with the same DL beam, enabling the UE to evaluate the quality of the different receive beams. In this case, no report from the UE is required.

Fig. 1 shows beam management 100 in the described P1 (101), P2 (102) and P3 (103) procedures according to the prior art. The gNB 105 is expected to perform the P2 procedure 102 based on the beam selected in the P1 procedure 101. Specifically, a narrow beam within the selected SSB is transmitted in P2 process 102.

In the P1 procedure 101 in fig. 1, the UE 110 transmits the PRACH 120 associated with ssb#1 125. Then, as part of the P2 procedure, CSI-RS #0 130, CSI-RS #1 135, and CSI-RS #2 140 are transmitted as narrow beams associated with SSB #1 125.

Based on the reported L1-RSRP 126, a reasonable gNB 105 behavior is to use one of the well-reported beams to send another CSI-RS using the same downlink spatial domain transmission filter. In fig. 1, UE 110 reports CSI-RS #0 130 during P2 procedure 102. Thus, in P3 process 103, the same downlink spatial-domain transmission filter is applied to CSI-RS 3-6, which may be the same as the downlink spatial-domain transmission filter corresponding to CSI-RS #0 130.

Although this description does not explicitly mention P1, UE 110 implicitly understands it as part of the initial access procedure. The other two processes are not explicitly referred to as P2 and P3. Instead, the gNB 105 implicitly indicates these procedures by using RRC parameter repetition in a non-zero power (NZP) -CSI-RS-resource set Information Element (IE).

Specifically, for a particular NZP-CSI-RS-resource set, if the repetition is set to off and the reporting amount associated with the NZP-CSI-RS-resource set is L1-RSRP 126, UE 110 may assume that the CSI-RS set is for P2 procedure 102. In other words, UE 110 may not assume the same beam for CSI-RS belonging to the NZP-CSI-RS-resource set (with repetition set to off).

However, if the repetition is set to on and the reporting amount associated with NZP-CSI-RS-resource set is none, UE 110 may assume that the CSI-RS set is for P3 procedure 103. In other words, UE 110 may assume that the same beam is used for all CSI-RSs belonging to NZP-CSI-RS-resource set (with repetition set to on).

NR version 18 (rel.18) introduces an NR controlled repeater, called intelligent repeater. The repeater is designed to address the problems of insufficient coverage and excessive cost. The repeater typically does not have a full-stack cell (full-stack cell) compared to a conventional gNB or integrated access and backhaul (integrated access and backhaul, IAB), which can significantly reduce the cost of the repeater.

Fig. 2 shows a repeater 200 to which the network control of the present disclosure is applied. That is, although any suitable repeater can be applied to the present application, the network-controlled repeater 200 will now be described.

In fig. 2, a network controlled repeater 200 or intelligent repeater as disclosed herein includes a network controlled mobile terminal (NCR-MT) component 201 and an NCR forwarding (NCR-Fwd) component 202. The NCR-MT 201 communicates with the gNB 205 via a control link (C-link) 203 to enable exchange of side control information at least for control of the NCR-Fwd 202. The C-link 203 is based on the NR Uu interface. NCR-Fwd 202 amplifies UL/DL RF signals and forwards UL/DL RF signals between gNB 205 and UE210 via backhaul link 204 and access link 206. The behavior of NCR-Fwd 202 is controlled based on the side control information received from the gNB 205. Note that the NCR-MT 201 is similar to a conventional mobile terminal in that the NCR-MT 201 includes memory and a processor in this manner of mobile terminal.

One enhancement of intelligent repeaters involves increasing spatial beamforming on the repeater-UE link while maintaining the transparency of the repeater to the UE.

Intelligent repeaters or reconfigurable intelligent surfaces (reconfigurable intelligence surface, RIS) can be deployed to enhance coverage without the need to implement expensive gnbs or IAB nodes. The intelligent repeater or RIS may amplify and forward or reflect, respectively, the received signal/channel from the gNB-repeater link to a particular direction, which may be different from the direction of the received signal/channel. To minimize costs, it is desirable that the intelligent repeater and RIS be fully controlled by the gNB or IAB node and can be transparently deployed to minimize UE impact. Here, intelligent repeater and RIS are used interchangeably.

With respect to beam training (P1, P2, and P3), a repeater may construct its own beam depending on the area to be covered. Thus, assuming that a repeater can construct its own beam but cannot generate its own reference signal/channel, a new procedure should be developed for beam training. For example, in the P1 and P2 processes, the repeater may receive only one beam for DL RS from the gNB, and must use the beam to perform beam training according to the P1 and P2 processes. In conventional NR, the P1 and P2 processes are performed using different RS IDs, so that the UE can report the quality of each beam of measurements, e.g., report L1-RSRP 126. Thus, some enhancements may also be needed to address this problem.

In the P3 procedure, the UE assumes that the RS is transmitted with the same DL beam so that the UE can train its own receive beam. Thus, when a repeater amplifies and forwards such a signal, it should maintain such characteristics to avoid adversely affecting the UE.

Regarding beam fault recovery, the gNB in the legacy NR knows the list of configured candidate beams and their associated RACH resources, e.g., RACH Occasions (ROs) or preamble Identifiers (IDs), which the gNB monitors to receive any potential transmit beam fault recovery request (BFRQ). Thus, the repeater should be aware of the RACH resources that should be monitored and the corresponding candidate beams based on repeater beamforming.

The problem with the above approach relates to Physical Downlink Shared Channel (PDSCH)/Physical Uplink Shared Channel (PUSCH) scheduling. That is, since the repeater can construct its own beam but cannot generate its own reference signal/channel, when the gNB tries to schedule DL or Uplink (UL), the repeater should know which beam should be used for transmission or reception. For example, in a legacy NR, a Transmission Configuration Indicator (TCI) field in scheduling Downlink Control Information (DCI) can indicate a DL beam for a corresponding PDSCH so that a UE can adjust its reception beam. The repeater in the above method does not know such information for correctly forwarding PDSCH.

Similarly, for PUSCH, the repeater is unaware of the receive beam that should be applied. Thus, there is a need in the art for some enhancements to address this lack of awareness and inform the repeater of the beams used to transmit or receive different DL or UL signals and channels to improve beam transmission and reception and facilitate more efficient wireless transmissions.

The same requirements apply for Physical Downlink Control Channel (PDCCH)/Physical Uplink Control Channel (PUCCH). Specifically, the repeater should know which beams should be used to transmit the PDCCH or receive the PUCCH.

One aspect of the present disclosure is to provide an intelligent repeater that can be equally applied to reconfigurable intelligent surfaces.

One aspect of the present disclosure provides a solution for beam management in a P2 procedure when a repeater is deployed by mapping CSI-RSs sent on a gNB-repeater link to actual beams on a repeater-UE link to provide signaling, enabling the gNB to signal the time domain location of the CSI-RSs for the P2 procedure, and enabling the repeater to inform the gNB of the mapping of the CSI-RSs to beams on the repeater-UE link.

The above-described method improves upon previous methods by enabling the repeater to freely select the beam for forwarding the CSI-RS.

One aspect of the present disclosure provides a solution for the gNB to inform the relay of which CSI-RSs to use in the P3 procedure, and develops a framework to inform the relay of the configuration of UEs served by the relay.

The above-described method improves the previous method by informing the repeater of the actual beam to be applied to transmission or reception of the DL or UL signal.

One aspect of the present disclosure provides time domain information of symbols occupied by different channels (e.g., PDSCH, PDCCH, PUSCH or PUCCH) to a relay with reduced signaling overhead, and provides a procedure for the gNB to indicate which beam should be applied to the different channels.

One aspect of the present disclosure provides a prioritization rule to be applied to determine which beam should be used by a repeater on a repeater-UE link when there is a collision with an indicated beam at a particular symbol.

One aspect of the disclosure provides rules for the UE to determine to apply a default beam when no other indication is provided from the gNB.

An aspect of the present disclosure is to provide a solution for RS for beam fault detection or candidate beam identification.

In an embodiment, a method of determining an access link beam by a repeater includes: receiving an indication of a beam index from a base station, the beam index comprising the indicated beam and a corresponding time at which the indicated beam was applied; and transmitting at least one set of resources using the indicated beam.

In an embodiment, a method of a repeater includes: the method includes receiving a downlink transmission from a base station, selecting a backhaul beam from a pool of identical Transmission Configuration Indicator (TCI) states for a backhaul link between the base station and a forwarding unit of a relay, and forwarding the downlink transmission to a UE.

In an embodiment, an apparatus includes at least one processor and at least one memory operably connected to the at least one processor, the at least one memory storing instructions that, when executed, instruct the at least one processor to perform a method of a repeater by: the method includes receiving a downlink transmission from a base station, selecting a backhaul beam from a same TCI state pool for a backhaul link between the base station and a forwarding unit of a relay, and forwarding the downlink transmission to a UE.

Drawings

In the following sections, aspects of the subject matter disclosed herein will be described with reference to exemplary embodiments shown in the drawings, in which:

fig. 1 shows beam management 100 in describing P1, P2 and P3 according to the prior art;

fig. 2 shows a repeater 200 to which the network control of the present disclosure is applied;

fig. 3 illustrates an example 300 of NZP-CSI-RS-resource set with repetition provided to a UE set to off according to an embodiment;

Fig. 4 shows an example 400 of SSB mapping to different beams on a relay-UE link, in accordance with an embodiment;

fig. 5 illustrates an example 500 of indicating beams for forwarding SSBs and CSI-RSs, according to an embodiment;

fig. 6 illustrates a DCI-based indication of CSI-RS for a P2 procedure 600 according to an embodiment;

fig. 7 illustrates a mapping 700 of CSI-RS from a gNB to multiple beams on a relay-UE link, in accordance with an embodiment;

fig. 8 illustrates a mapping 800 of SSBs from a gNB to multiple beams on a relay-UE link, in accordance with an embodiment;

fig. 9 illustrates a mapping 900 of multiple CSI-RSs from a gNB to beams on a relay-UE link, in accordance with an embodiment;

fig. 10 illustrates a method 1000 for information exchange between a gNB and a repeater for a beam management process, according to an embodiment;

fig. 11 illustrates a medium access control-control element (MAC-CE) indicating a mapping 1100 of CSI-RS on a gNB-relay link to actual beams on a relay-UE link, according to an embodiment;

fig. 12 shows an indication 1200 of CSI-RS Id and accompanying time domain position according to an embodiment;

fig. 13 illustrates an indication 1300 of CSI-RS belonging to the same NZP-CSI-RS resource set, according to an embodiment;

fig. 14 illustrates a beam indication and its characteristics 1400 according to an embodiment;

Fig. 15 illustrates a beam and quasi co-located (QCL) -type indication 1500 according to an embodiment;

FIG. 16 illustrates field indications for a P2 or P3 process 1600, according to an embodiment;

fig. 17 shows a P2 and P3 process 1700 according to an embodiment;

fig. 18 illustrates TCI status indications for a forwarding beam 1800 according to an embodiment;

fig. 19 illustrates a Start and Length Indicator Value (SLIV) method 1900 of indicating DL forwarding locations and corresponding beams, according to an embodiment;

fig. 20 illustrates the handling of beam indication collisions at a repeater 2000 according to an embodiment; and

fig. 21 is a block diagram of an electronic device in a network environment 2100, according to an embodiment.

Detailed Description

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be understood by those skilled in the art that the disclosed aspects may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to obscure the subject matter disclosed herein.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment disclosed herein. Thus, the appearances of the phrase "in one embodiment" or "in an embodiment" or "according to one embodiment" (or other phrases having similar meaning) in various places throughout this specification may not necessarily all refer to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In this regard, as used herein, the word "exemplary" means "serving as an example, instance, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Furthermore, depending on the context discussed herein, singular terms may include corresponding plural forms and plural terms may include corresponding singular forms. Similarly, hyphenated terms (e.g., "two dimensions," "predetermined," "pixel-specific," etc.) may be occasionally used interchangeably with corresponding non-hyphenated versions (e.g., "two-dimensional," "predetermined," "pixel-specific," etc.), and uppercase entries (e.g., "counter clock," "row select," "pixel output," etc.) may be used interchangeably with corresponding non-uppercase versions (e.g., counter clock, row select, pixel output, etc.). Such occasional interchangeable uses should not be considered inconsistent with each other.

Furthermore, depending on the context discussed herein, singular terms may include corresponding plural forms and plural terms may include corresponding singular forms. It should also be noted that the various figures (including component figures) shown and discussed herein are for illustrative purposes only and are not drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals have been repeated among the figures to indicate corresponding and/or analogous elements.

The terminology used herein is for the purpose of describing some example embodiments only and is not intended to limit the claimed subject matter. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

It will be understood that when an element or layer is referred to as being "on," "connected to" or "coupled to" another element or layer, it can be directly on, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly connected to" or "directly coupled to" another element or layer, there are no intervening elements or layers present. Like numbers refer to like elements throughout. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

As used herein, the terms "first," "second," and the like are used as labels for nouns following them, and do not imply any type of ordering (e.g., spatial, temporal, logical, etc.), unless so defined explicitly. Furthermore, the same reference numbers may be used throughout two or more drawings to refer to parts, components, blocks, circuits, units, or modules having the same or similar functionality. However, such use is merely for simplicity of illustration and ease of discussion; it is not intended that the construction or architectural details of such components or units be the same in all embodiments, or that such commonly referred parts/modules be the only way to implement some example embodiments disclosed herein.

Unless defined otherwise, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this subject matter belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

As used herein, the term "module" refers to any combination of software, firmware, and/or hardware configured to provide the functionality described herein in connection with the module. For example, software may be embodied as a software package, code, and/or instruction set or instructions, and the term "hardware" as used in any of the embodiments described herein may include, for example, components, hardwired circuitry, programmable circuitry, state machine circuitry, and/or firmware that stores instructions executed by the programmable circuitry, either alone or in any combination. Modules may be collectively or individually embodied as circuitry forming part of a larger system, such as, but not limited to, an Integrated Circuit (IC), a system-on-a-chip (SoC), a component, and the like.

Beam training

Although embodiments of the present disclosure are described with reference to a particular beam management procedure (i.e., P1, P2, or P3), they may be equally applicable to other procedures. For example, the procedure described for P2 may be equally applied to P1, and the procedure for forwarding CSI-RS for P2 may be equally applied and extended to forwarding SSB used in P1.

In conventional NR, in order to transmit beam refinement on the gNB side, a P2 procedure may be used to transmit finer DL beams to the UE, which in turn reports the measured L1-RSRP and corresponding CSI-RS index. Using RRC parameter repetition in the NZP-CSI-RS-resource IE, the gNB can indicate whether to apply the P2 procedure. Specifically, if the repetition is set to off, the UE may not assume that the NZP-CSI-RS resources within the resource set are transmitted using the same downlink beam. In other words, different DL beams can be applied to different CSI-RSs in the same NZP-CSI-RS-resource set.

The relay does not know the CSI-RS configuration of its UE

To simplify the implementation of the relay, the relay may not be required to decode CSI-RS configuration of each UE served by the relay, or to decode trigger DCI for aperiodic CSI-RS or (de) activate MAC-CE for semi-persistent CSI-RS. This may be beneficial when the repeater serves many UEs, and imposing such requirements on the repeater (i.e., knowing CSI-RS information for each UE) may result in a more complex repeater with higher costs.

To this end, the gNB may indicate to the repeater when the received signal/channel on the gNB-repeater link can be used for beam scanning purposes on the repeater-UE link. In this case, the repeater does not have to know the CSI-RS configuration of the different UEs served by the repeater. Instead, the repeater should know when it is free to use such signals/channels for the P2 procedure. However, the UE still receives the configuration/activation/triggering of CSI-RS according to the conventional procedure, but still is unaware of the presence of the relay.

Fig. 3 illustrates an example 300 of NZP-CSI-RS-resource set 301 provided to UE 310 with repetition set to off, according to an embodiment. In fig. 3, a UE 310 desires to transmit CSI-RSs belonging to the NZP-CSI-RS-resource set 301 using different transmission (Tx) beams. Using the indicators disclosed in this disclosure from gNB 305 to repeater 315, repeater 315 becomes aware of how to scan the transmit beam on the repeater 315-UE 310 link.

Specifically, NZP-CSI-RS-ResourceNet 301 comprises CSI-RS#0-6 325, 330, 335, 340, 345, 350, 355 and is repeatedly set to off. Although repeater 315 receives all CSI-RSs using the same beam 320 on the gNB 305-repeater 315 link, repeater 315 applies different transmit beams for different CSI-RSs to effectively have the same functionality of legacy P2 from the perspective of UE 310. As will be described in more detail below, the indication from the gNB 305 to the relay 315 may carry information to inform the relay 315 of the location of different CSI-RSs for which different transmissions may be applied, and the relay 315 applies different beams for the different CSI-RSs.

Using a similar approach for CSI-RS of P2, the gNB may transmit multiple SSBs on the gNB-repeater link, or the gNB may transmit SSBs using multiple beams and the repeater has the ability to receive them. Thereafter, the repeater may apply different transmit beams for different SSBs to effectively have the same function of conventional P1 from the perspective of the UE and to cover the intended area.

Fig. 4 illustrates an example 400 of SSB mapping to different beams on a relay-UE link, in accordance with an embodiment. FIG. 4 is similar to FIG. 3, but with respect to SSB 402.

In fig. 4, SSB indices {0,2,5,6}425, 430, 435, 440 are indicated as being forwarded by repeater 415. In this case, repeater 415 amplifies and forwards the SSBs, and repeater 415 forwards the SSBs using different beams. Since SSBs are assigned to specific locations in the time domain, repeater 415 may forward SSBs assigned only to repeater 415. The remaining SSBs may not be forwarded even though they are received by repeater 415. This is depicted, for example, by the X-marks in SSB {1,3,4,7}450, 455, 460, 465 in fig. 4.

Associating DL signals/channels with transmit beams at a repeater (P2 procedure)

In the P2 procedure, the repeater is free to construct the actual beam on the repeater-UE link to forward the RS received from the gNB for the P2 procedure on the gNB-repeater link. There are several possibilities to map these RSs on the gNB-relay link to the actual beam on the relay-UE link.

Some constraints may be applied depending on how many SSBs are forwarded in P1. For example, if the repeater forwards only a single SSB, the beam for the RS used in P2 can be freely constructed by the repeater. This may be equivalent to forwarding SSBs using omni-or semi-omni-directional beams, and then constructing beams for RSs of P2 by the repeater, as long as they are within SSB coverage. If there are multiple SSBs forwarded by the repeater during P1, the repeater may construct a beam for the RS of P2 based on the associated SSBs. For example, the repeater may construct a narrow beam for CSI-RS within the coverage of the associated SSB, in which case the RS for P2 may be handled in the manner of a P3 procedure in terms of an indication of the associated beam and an indication of when to apply the associated beam.

The gNB and the relay should have a common understanding on how to map the RSs from the different transmissions of the gNB to the downlink transmit beam at the relay. That is, the gNB should know which beams and corresponding RSs can be used for scheduling.

One-to-one mapping

In the one-to-one mapping method, each RS for beam management is mapped to a single beam DL on the repeater-UE link, as shown in fig. 3 and 4, where CSI-RS #0-6 325-355 and SSB # {0,2,5,6}425-440 are mapped to 7 and 4 beams on the repeater-UE link, respectively, one-to-one.

In this case, when the UE reports the measured beam quality (e.g., L1-RSRP) and the corresponding CSI-RS, there will be no ambiguity between the UE and the gNB.

By using relay capability signaling similar to UE capability signaling, it is signaled from the relay to the gNB whether the relay supports such mapping.

The repeater may also indicate the number of RSs in which a one-to-one mapping can be applied. Effectively, the repeater may indicate the number of beams that can be constructed on the repeater-UE link. Further, the number of RSs mapped one-to-one to the actual beam on the repeater-UE link within a particular time frame may be indicated. For example, the repeater may indicate that up to 2 RSs can be mapped to three different beams, as shown in slot 3 in fig. 3.

After the association between the RS sent on the gNB-relay link and the actual beam on the relay-UE link, the relay is not expected to change the association unless indicated by the gNB. This enables the gNB to indicate to the repeater which beam should be used to forward DL signals/channels, and the gNB to indicate to the UE which beam should be used for reception on the repeater-UE link, since the repeater cannot create its own signals/channels.

Since the relay does not know the CSI-RS configuration and its purpose, the gNB may provide the following information to the relay. In particular, the gNB may indicate that the purpose of the forwarded RS is for beam management. For example, if a P2 procedure is indicated, the repeater may apply a different beam for each forwarded RS. Table 1 below shows an explanation of the destination field.

TABLE 1

Purpose(s)	Interpretation of the drawings
		0	Reference signals for P2 procedure in beam management
1	Reference signals for P3 procedure in beam management

If the repeater forwards multiple SSBs during the P1 procedure, the gNB can inform the repeater of the associated beams used when forwarding SSBs in P1 regarding which beams will be used to forward RSs for the P2 procedure. The procedure described herein that allows the gNB to indicate which beam the repeater uses may be applied here. The gNB indicates to the repeater which beam to use, similar to the beam indication procedure used for the P3 procedure or for forwarding the different channels herein. On the other hand, during P2, the gNB indicates the associated beam for SSB to the relay. That is, the repeater does not need to use the same width beam for forwarding SSBs, but rather can use a narrower beam for CSI-RS. However, those narrow beams may be related to the associated wide beams used to forward SSBs, e.g., the narrow beams may have the same spatial direction and QCL type D characteristics.

In this case, in addition to indicating the associated beam, providing the purpose information as in table 1 is advantageous in helping the repeater determine whether the indicated beam should be applied identically or the repeater has the freedom to alter the beam while maintaining some characteristics, such as a particular direction, e.g., QCL type D.

The destination information may be indicated explicitly or implicitly. When the gNB indicates to the relay an index for forwarding the transmitted beam, an implicit indication method may be implemented. Some of them may be dedicated to indicating that the repeater can freely construct the forward beam while possibly keeping some characteristics the same. For example, if the gNB indicates to the relay that the transmission is being forwarded on the relay-UE link using a beam from the set of beams used to forward the SSB, the relay may infer that a narrower beam can be constructed while maintaining some common characteristics, such as spatial direction.

Fig. 5 illustrates an example 500 indicating beams for forwarding SSB 502 and CSI-RS 501, according to an embodiment. Specifically, fig. 5 shows how the repeater 515 forwards 4 SSBs 525, 530, 535, 540 using a wide beam over the repeater 515-UE 510 link. The gNB 505 also instructs the relay 515 to forward groups of CSI-RSs 501 associated with each SSB 502, where each group has 3 CSI-RSs. For a particular group of CSI-RS 501, the forwarding narrow beams of all CSI-RS on the repeater 515-UE 510 link are associated with the same wide beam used to forward the particular SSB on the repeater 515-UE 510 link. In this case, the repeater 515 constructs a different narrow beam for each CSI-RS 501, but these narrow beams have common characteristics with the associated wide beam, such as a special direction. In other words, the relay 515 forwards these CSI-RSs 501 such that, from the perspective of the UE 510, the broad beam for forwarding the associated SSB 502 represents the source RS for QCL type D.

For time domain information, the gNB may indicate to the relay which symbols/slots/subframes carrying RSs for the P2 procedure to use in beam management. The gNB may indicate a start symbol and a number of symbols of each RS for beam management to the relay. For example, a plurality of Start and Length Indicator Values (SLIV) can be indicated to point to the location of the RS within one slot.

Since the CSI-RS for beam management is a single port or two ports, the CSI-RS will occupy only one Orthogonal Frequency Division Multiplexing (OFDM) symbol according to the CSI-RS configuration. In this case, the bit map may be used to indicate the positions of CSI-RSs for beam management. The length of the bitmap may be 14 bits covering one time slot or more than 14 bits covering multiple consecutive time slots until the next occasion to transmit the indicator. Each bit may correspond to one or more symbols and the granularity of each bit in the bitmap may be indicated to the repeater or predefined in the specification.

At least for cell-defined SSBs, the destination information may not be indicated, since the relay should be able to detect SSBs from the gNB, similar to a typical UE. The repeater may freely determine the forward beam on the repeater-UE link based on the area intended for coverage. Furthermore, the repeater should be able to determine the time domain location of the SSB, similar to a typical UE. Thus, the gNB may not need to determine the time domain of the SSB, and may not need to instruct the repeater to forward the SSB each time to reduce signaling overhead.

The gNB may indicate which SSBs of the set of SSBs received by the repeater are to be forwarded by the repeater. When the repeater receives these SSBs, the repeater forwards them and determines a forwarding beam. However, for the same SSB index across different SSB burst sets, the repeater is expected to use the same beam.

For example, the repeater forwards all received SSBs and determines the beam to use based on the coverage area. Alternatively, the gNB may indicate which SSB set the relay is able to forward. The gNB may provide the repeater with a bit map indicating which SSBs the repeater is able to forward. This may be achieved by higher layer signaling. For example, RRC parameters similar to ssb-PositionInBurst may be sent to the repeater in the remaining System information/other System information (RMSI/OSI) and may be marked by ssb-PositionInBurst-r 18. The bit map may be indicated by higher layer signaling other than RMSI/OSI, e.g. RRC IE dedicated to the repeater, to avoid affecting RMSI/OSI.

Whenever the relay receives an SSB indicated by the gNB as described above, the relay may forward the SSB, and the relay may also forward RMSI-PDCCH and RMSI-PDSCH associated with the indicated SSB to be forwarded by the relay. Similar to SSBs, the gNB may not need to instruct the relay to forward each RMSI individually, but may assume that the RMSI-PDCCH and RMSI-PDSCH associated with the indicated SSB should be forwarded without explicit instructions from the gNB. Further, when forwarding RMSI-PDCCH and RMSI-PDSCH, the repeater may use the same beam as that used to forward the corresponding SSB.

For example, when ssb-PositionInBurst-r 18 is included in the RMSI, it may also be beneficial for the UE to receive ssb-PositionInBurst-r 18. In this case, the UE may be aware of the presence of the relay and may determine that it is being served by the relay. In particular, if the SSB ID of the SSB selected by the UE for accessing the system belongs to SSB-locationinburst-r 18, the UE can assume that it is served by the repeater. Otherwise, if the SSB ID of the SSB selected by the UE for accessing the system belongs to SSB-locationinburst (without suffix), the UE can assume that it is served by the gNB. If the UE is served by a repeater, the UE may assume that the RBs spanned by the SSB index in SSB-PositionInBurst-r 18 are not available for PDSCH, while the RBs spanned by the SSB index in sb-PositionInBurst (without suffix) are available for PDSCH. However, if the UE is served by the gNB, the UE may assume that RBs spanned by SSB indexes in SSB-locationinburst (without suffix) are not available for PDSCH, while RBs spanned by SSB indexes in SSB-locationinburst-r 18 are available for PDSCH.

The UE may expect the SSB index sets in the locationinburst (without suffix) and SSB-locationinburst-r 18 to be mutually exclusive.

This indication from the gNB to the relay may be sent as DCI in a PDCCH with a Cyclic Redundancy Check (CRC) scrambled by the Radio Network Temporary Identifier (RNTI) of the relay. The RNTI can be similar to a cell-radio network temporary identifier (C-RNTI). In this case, the relay may have at least two RNTIs, one of which may be used to scramble DCI carrying beam information from the gNB to the relay, and the other may be used in a similar manner to a typical UE, such as for receiving a dedicated configured C-RNTI. Conventional methods of configuring a Search Space (SS) set and a control resource set (CORESET) for a UE may be applied to a repeater.

Fig. 6 illustrates a DCI-based indication of CSI-RS for a P2 procedure 600 according to an embodiment. In particular, fig. 6 shows a PDCCH from the gNB to the relay, carrying a bit map indicating the location of CSI-RS for the P2 procedure. Each indication has 18 bits to indicate the position in two consecutive time slots. In this case, the repeater applies a different beam for each symbol 602 carrying CSI-RS. Using PDCCH to carry this indication may be beneficial for fast adjustment of the beam. For example, if the gNB triggers aperiodic CSI-RS for the P2 procedure, the gNB may use DCI 601 to inform the relay of the locations of those CSI-RS so that the relay may apply different beams to the UE.

Although the previous examples are explained for CSI-RS, the bitmap indication may be used to indicate the time position of SSBs, such as non-cell-defined SSBs for different purposes (such as for P2 procedures).

The indication from the gNB to the relay may be sent via higher layer signaling, which may also be beneficial in reducing signaling overhead. For example, the gNB may send a MAC-CE to the relay indicating symbols carrying CSI-RS or SSB. This may take the form of a bitmap, where each bit may correspond to one or more symbols/slots, and the granularity of each bit in the bitmap may be indicated to the repeater or predefined in the specification.

Since the indication spans a limited period of time, where the period may be configured by RRC or indicated by MAC-CE, the indicated pattern of symbols carrying CSI-RS or SSB may be repeated continuously until another instruction is received, e.g. modifying or deactivating the pattern. In other words, the provided indication is applied periodically until a deactivated MAC-CE is received. If the RRC configures multiple periods, the MAC-CE can select a period to apply. The period may be in units of frames, subframes, slots, OFDM symbols, absolute time units (such as milliseconds, seconds, etc.).

The use of MAC-CEs to carry the indication may also be beneficial and well suited for semi-persistent CSI-RS activated by MAC-CEs.

After the relay sends a hybrid automatic repeat request acknowledgement (HARQ-Ack) of the MAC-CE, the finger provided from the gNB to the relay over the MAC-CEThe illustration may be applicable. For example, it may be in time slotsThe indication is applied in the first time slot thereafter, where n is the time slot of the HARQ-Ack for the MAC-CE.

When using RRC, the specific offset to which the indicator is applied may be signaled by higher layer signaling or predefined based on some rules.

Alternatively, the gNB may use RRC parameters to provide information to the relay regarding the location of the CSI-RS or the location of the SSB for the P2 procedure. The RRC parameter may be a bitmap, where each bit may correspond to one or more symbols/slots, and the granularity of each bit in the bitmap may be indicated to a repeater or predefined. Since the indication spans a limited period of time, the indicated pattern of symbols carrying CSI-RS or SSB may be repeated continuously until another instruction is received, such as modifying or releasing the pattern. In other words, the provided indication is applied periodically until a release command is received.

Alternatively, another bit map may be provided to indicate a repeating pattern of the aforementioned bit map, which may repeat itself continuously.

One-to-many mapping

Fig. 7 illustrates a mapping 700 of CSI-RS from a gNB705 to multiple beams on a repeater 715-UE 710 link, according to an embodiment. In fig. 7, repeater 715 may be capable of constructing multiple beams simultaneously, such as the following beam tuples: (702, 708), (704, 712), (706, 714), in which case the number of CSI-RSs configured by the gNB705 may be reduced. The repeater 715 in fig. 7 forwards each CSI-RS 720, 725, 730 using two different beams.

If the beams are spatially separated in a sufficient manner, the UE 710 receives only one version of the same CSI-RS at any time instance. If not, the UE 710 will receive the same CSI-RS transmitted on a different beam. This may be uncorrelated, as the UE 710 may handle this as if CSI-RS were received from multiple paths.

The same procedure described in the one-to-one mapping procedure may be extended to a one-to-many procedure for indicating repeater capability, purpose of CSI-RS, their location, etc.

Fig. 8 illustrates a mapping 800 of SSBs 801 from the gNB 805 to multiple beams on a repeater 815-UE 810 link, according to an embodiment. In particular, the repeater 815 may forward the same SSB over multiple beams simultaneously on the repeater 815-UE 810 link, which may be beneficial to reduce the number of SSBs that the gNB 805 needs to allocate for the repeater 815. In contrast to fig. 4, the gNB 805 instructs the repeater 815 to forward only two SSBs, as shown in fig. 8, instead of the 4 SSBs in the previous example.

The same procedure described in the case of one-to-one mapping can be extended to the case of one-to-many mapping for indicating repeater capabilities, the purpose of SSBs, their locations, etc.

Many-to-one mapping

In some cases, the repeater may have limited capabilities and may not be able to construct a different beam for each forwarded CSI-RS or SSB as in the case of a one-to-one mapping, or may not be able to construct multiple beams for each CSI-RS or SSB as in the case of a one-to-many mapping.

Fig. 9 illustrates a mapping 900 of multiple CSI-RSs 902 from a gNB 905 to beams on a repeater 915-UE 910 link, according to an embodiment. In particular, according to the set of CSI-RSs 902 determined to map to one beam, multiple forwarded CSI-RSs can be mapped to the same beam on the repeater 915-UE 910 link, and the repeater 915 applies the same beam in each transmit occasion associated with the CSI-RS 902. As shown in fig. 9, CSI-rs#0, CSI-rs#1, and CSI-rs#2 belong to one set mapped to the same beam 925. Therefore, the same beam is used when the repeater forwards CSI-RS #0, CSI-RS #1, and CSI-RS #2 in its corresponding time occasion. Similarly, CSI-rs#3 and CSI-rs#4 are mapped to the same beam 930, and CSI-rs#5 and CSI-rs#6 are mapped to another beam 935.

The same procedure described in the case of one-to-one mapping can be extended to the case of many-to-one mapping for indicating repeater capability, purpose of CSI-RS, their location, etc.

Although the previous examples are directed to CSI-RS, the same concepts can be easily extended when the relay forwards SSBs on the relay-UE link.

From the UE's perspective, legacy behavior may be applied and each CSI-RS may be treated as if it were sent from a different beam, and corresponding measurements, e.g. L1-RSRP, may be reported even though they are mapped to the same beam.

The relay-assisted gNB associates the RS with the actual beam

Fig. 10 illustrates a method 1000 for information exchange between a gNB 1005 and a relay 1015 for a beam management process, according to an embodiment.

Whichever mapping procedure is applied, it may be beneficial for the repeater to indicate its capabilities to the gNB. In step 1, the relay may indicate its capability, such as one-to-one mapping, one-to-many mapping, or many-to-one mapping, as to how CSI-RSs or SSBs on the gNB 1005-relay 1015 link will map to actual beams on the relay 1015-UE 1010 link. The capability may also include the number of beams that the repeater 1015 can construct per SSB or the number of SSBs that the repeater 1015 needs to cover the intended area.

In step 2, with such information, the gNB 1005 can decide how many RSs or SSBs are expected to be transmitted for beam management purposes and send the configuration to the relay 1015, which relay 1015 amplifies the configuration and forwards it to the UE 1010.

Since the repeater 1015 only amplifies and forwards the configuration of the RS, the repeater 1015 will not know the corresponding location that the gNB 1005 can indicate. Thus, in step 3, the gNB 1005 indicates to the relay 1015 the set of SSBs to be forwarded on the relay 1015-UE 1010 link, such as by indicating the purpose and location of the CSI-RS, which enables the relay 1015 to select their corresponding beams, as previously described.

In step 4, based on the information provided to the relay 1015, the relay 1015 decides which beam to apply to which CSI-RS or SSB.

In step 5, the repeater 1015 may inform the gNB 1005 which CSI-RS or SSB is mapped to which actual beam. Step 5 is not necessary in a one-to-one mapping; however, for many-to-one and one-to-many mappings, step 5 is beneficial to enable the gNB 1005 to be aware of such associations for facilitating scheduling.

Although the repeater does not know the actual index of the CSI-RS sent on the gNB-repeater link, the repeater may know the total number of CSI-RS for P2 based on the indicator provided from the gNB. If it is a bit map, for example, as shown in fig. 6, the total number of CSI-RSs is the total number of bits set to 1. In this case, the repeater may provide the gNB with information for mapping the CSI-RS on the gNB-repeater link to the actual beam on the repeater-UE link, as shown in Table 2 below.

When forwarding SSBs, the relay knows the SSB ID, similar to any typical UE. The repeater may provide the gNB with information similar to that shown in Table 2 below. Except that the left column includes SSB IDs, the repeater can determine SSB IDs similar to a typical UE.

TABLE 2

Fig. 11 illustrates a MAC-CE indicating a mapping 1100 of CSI-RS on a gNB-relay link to actual beams on a relay-UE link, according to an embodiment. As shown in fig. 11, if the repeater receives a plurality of bitmaps indicating the presence of CSI-RS, the repeater may concatenate the bitmaps to construct the information in table 2 until such information is provided to the gNB. The repeater may use MAC-CE to transmit such information as shown in fig. 11. For example, the repeater can provide this information to the gNB through higher layer signaling such as RRC or MAC-CE. Another MAC-CE may separately indicate the actual beam used to forward the SSB, and the CSI-RS index in fig. 11 may be replaced with the SSB index. Alternatively, the same MAC-CE may carry information about the mapping of CSI-RS and SSB. In this case, an additional octal number (Oct) may be introduced to carry the SSB index and the corresponding beam index. Further, an additional 1-bit field may be introduced to indicate whether the MAC-CE carries mapping information of CSI-RS or mapping information of both CSI-RS and SSB.

In some cases, some rules can be used to perform mapping between CSI-RS in the repeatedly turned-off NZP-CSI-RS-resource set and the actual beam on the repeater-UE link. For example, in one-to-one mapping, a CSI-RS indicated with a most significant bit set to 1 in a time domain bit map may be mapped to an actual beam #1, a CSI-RS indicated with a second most significant bit set to 1 in a time domain bit map may be mapped to an actual beam #2, and so on. The same concept can be extended to SSB. Specifically, in the case of one-to-one mapping, within the SSB set that the gNB instructs the repeater to forward, the SSB with the lowest ID is mapped to the actual beam #1, the SSB indicated with the second lowest ID is mapped to the actual beam #2, and so on.

The same CSI-RS or SSB may occur multiple times depending on the duration spanned by the time indication method (e.g., bit map) used to inform the relay of the location of the CSI-RS or SSB. Furthermore, the same CSI-RS or SSB may occur in multiple time indications (such as consecutive bit patterns). This scenario occurs when periodic (P) or semi-persistent (SP) CSI-RS are configured, or even for multi-triggered Aperiodic (AP) CSI-RS, because QCL assumes AP CSI-RS are configured by RRC.

In case of periodic or semi-persistent resources, the UE expects the same beam for transmitting CSI-RS or SSB for each transmission occasion. Further, for AP-CSI-RS, once CSI-aperiodic trigger state (CSI aperiodic trigger state) is triggered by triggering CSI request field in DCI, UE expects to apply QCL source of the same configuration in CSI-associtreportconfigmnfo (CSI-associated report configuration information).

To maintain transparency of the presence of the relay to the UE, the gNB may indicate this information to the relay.

For example, the gNB may provide the repeater with a CSI-RS Id, e.g., NZP-CSI-RS-ResourceID and/or a corresponding resource set ID, NZP-CSI-RS-ResourceSID. For SSB, the gNB map provides SSB-indexes and/or csi-SSB-ResourceList (resource list) to the repeater. The gNB can provide the repeater with an index pair (CSI-RS Id, resource set Id) or (SSB Id, SSB resource set Id). This may be beneficial because the same CSI-RS or SSB may belong to multiple resource sets. For each CSI-RS or SSB, the gNB can provide the corresponding time domain location using the procedure described above or any other procedure.

Fig. 12 shows an indication 1200 of CSI-RS Id and accompanying time domain position according to an embodiment. In fig. 12, the gNB may indicate CSI-RS ids 1201, 1202 without providing the relay with a resource set Id to reduce signaling overhead. This information can be carried by DCI, MAC-CE or RRC.

Once the repeater receives this information, the repeater is free to select the beam when forwarding OFDM symbols carrying such CSI-RS or SSB. However, the same beam should be applied for each occasion of transmitting the CSI-RS or SSB. As described above, for cell-defined SSBs, the gNB may not need to indicate information about the SSB index or its time position, as such information can be easily determined by the relay similar to a typical UE. In this case, the repeater may continue to apply the same beam when forwarding the symbol containing the SSB every opportunity to transmit the SSB.

A specific timeline can be applied after which the indicated information is applied. The timeline may depend on how the information is carried.

For example, if the PDCCH is used to carry this information, the information may be applied K OFDM symbols after the last symbol carrying the PDCCH. The value of K may be configured or predefined. This may be similar for UE capability 1 or 2 for reception of PDSCH. The K OFDM symbols may be equal to timeduration for QCL indicated by the moving part of the repeater. In this case, the beam information indicated by the DCI may be applied after a timeduration forqcl time offset between the reception of the DCI carrying the beam indication and the time position of the beam to which the indication is to be applied.

For DCI-based indications, the number of bitmaps to be included in the DCI may be indicated by higher layer signaling or predefined. Since some bit map may not be used at a time, a special value may be indicated to inform the relay not to use the bit map while maintaining a fixed DCI payload size. For example, all zeros may be used as special values.

In the case where the indication is carried from the gNB to the relay using the MAC-CE, the relay may apply the provided indication after the relay transmits the HARQ-Ack for the MAC-CE. For example, it may be in time slotsThe indication is applied in the first time slot thereafter, where n is the time slot of the HARQ-Ack for the MAC-CE. When using RRC, the specific offset to which the indication applies may be signaled by higher layer signaling or predefined, or according to some rules as in the case of MAC-CE. The offset value may also indicate when the indicated beam is applied in the period of the beam indication and the same offset is applied in each period. The offset may be an offset to the time slot of the beam to which the indication is to be applied. The additional offset value may be indicated by higher layer signaling to indicate which symbol within the slot the indicated beam should be applied to.

The above operation may be beneficial for the P2 procedure and the relay may not need to report to the gNB how the CSI-RS is mapped to the actual beam on the relay-UE link. That is, the mapping to the actual beam may be transparent to the gNB.

When the gNB indicates to the relay which beam should be used to forward the DL transmission, the gNB can rely on information provided by the relay to indicate which beam should be used. Alternatively, the gNB may use SSB Id, CSI-RS Id, and/or corresponding resource set Id. In particular, throughout the disclosure, for each occasion that the gNB depends on information from the relay to indicate which beam the relay should use to forward DL transmissions, the gNB may use SSB Id, CSI-RS Id, and/or corresponding resource set Id. In this case, the repeater is expected to apply the same beam as that used for the indicated SSB or CSI-RS.

Associating DL signals/channels with transmit beams at a repeater (P3 procedure)

In the P3 procedure, the relay is not free to select the actual beam for forwarding CSI-RS to the UE. That is, when the repetition is set to on, the UE expects all CSI-RSs belonging to the same NZP-CSI-RS-resource set to be transmitted using the same beam. The repeater may not know which CSI-RSs belong to the same NZP-CSI-RS-resource set and whether the repetition is turned on or off. Further, in the P2 procedure, if the gNB indicates to the relay that the CSI-RS to be forwarded is associated with the beam for forwarding the specific SSB, the relay may be free to change the beam for forwarding the specific SSB to forwarding the CSI-RS while maintaining some common characteristics with the beam for forwarding the SSB, such as spatial direction, QCL type D as described above in fig. 5. In other words, as a possible example, the repeater forwards these CSI-RSs such that, at least from the perspective of the UE, the broad beam for forwarding the associated SSB represents the source RS of QCL type D for forwarding the beam of CSI-RSs.

When the UE is directly connected to the repeater, reasonable gNB behavior for performing the P3 procedure will send CSI-RS in the P3 procedure using the best beam reported by the UE in the P2 procedure. In other words, after the P2 procedure, the gNB knows the preferred DL beam based on the UE report. Thus, in the P3 procedure, the gNB is expected to use this beam for all CSI-RSs belonging to the same NZP-CSI-RS-resource set (with repetition set on). This may be beneficial because the UE adjusts its receive beam in the P3 procedure based on the best DL beam reported in the P2 procedure.

Since the relay only forwards reports from the UE to the gNB and does not decode these reports, the relay is not aware of the preferred DL beam indicated by the UE. In this case, the gNB should indicate to the relay which beams should be used during P3. Furthermore, the gNB may need to indicate to the relay which associated beams should be used for forwarding the RS for P2 and which common characteristics should be maintained between the beams used for forwarding the SSB and the beams used for forwarding the RS for P2.

For example, the gNB may provide the purpose (similar to the indication for P2 in table 1) and the time domain (similar to the time domain indication for P2) to the relay.

The repeater may need to know whether the indicated CSI-RS belongs to the same or different NZP-CSI-RS-resource set to determine whether the same beam should be applied.

Fig. 13 shows an indication 1300 of CSI-RSs belonging to the same NZP-CSI-RS-resource set, according to an embodiment. In fig. 13, it is assumed that CSI-RS whose time domain information is provided in one indication belong to the same NZP-CSI-RS-resource set. When DCI 1301 is used to carry a beam indication for CSI-RS, the repeater may assume that the CSI-RS indicated by a particular DCI belonging to NZP-CSI-RS-resource eset 1303 is different from NZP-CSI-RS-resource eset 1304 used by CSI-RS indicated by other DCI 1301, as shown.

When higher layer signaling (e.g., MAC-CE or RRC) is used, the same method may be used to implicitly indicate whether the indicated CSI-RS belong to the same or different NZP-CSI-RS-resource set.

Alternatively, the indication sent from the gNB to the relay may carry a flag indicating whether the indicated CSI-RS belongs to the same NZP-CSI-RS-ResourceNet or even an index of the NZP-CSI-RS-ResourceNet itself.

For example, an indicator (DCI, MAC-CE or RRC) may have multiple bitmaps indicating the time position of CSI-RS, where each bitmap corresponds to a particular NZP-CSI-RS-resource set.

Table 3 below shows how multiple bitmaps can indicate the locations of CSI-RS within one slot for multiple NZP-CSI-RS-resources. Each row corresponds to a particular NZP-CSI-RS-resource set. The repeater may not need to know the actual index of the NZP-CSI-RS-resource set.

TABLE 3 Table 3

Additional fields may be included to provide the repeater with an index to the NZP-CSI-RS-resource set associated with the indicated bit map. This solution may be beneficial to avoid having a dependency between the number of configured repeatedly turned-off NZP-CSI-RS-resource esets and the number of fields needed to indicate the position of the CSI-RS.

As described above, in P3, reasonable behavior will repeat CSI-RS belonging to a particular NZP-CSI-RS-resource set during the P2 procedure using the preferred beam indicated by the UE. Therefore, it would be beneficial if the gNB could indicate to the repeater which beam should be used by the repeater to transmit CSI-RS belonging to a particular NZP-CSI-RS-resource set (with the repetition set on).

For example, the gNB may employ information of how the CSI-RS in the gNB-relay link is mapped to the actual beam in the relay-UE link. The mapping information may be sent from the repeater to the gNB, as described above in FIG. 11, or by any other suitable method. In this case, the gNB may indicate to the repeater which beam should be applied to the CSI-RS belonging to the NZP-CSI-RS-resource set (with repetition set to on). For example, the CSI-RS in P2 is mapped to 16 actual beams, and a four-bit field can indicate to the relay which beam should be used in P3.

The field indicating the beam used to transmit the CSI-RS as part of P3 may be part of DCI, MAC-CE or RRC, depending on how the indicator is provided from the gNB to the relay.

In another method in which the gNB indicates to the relay which beam should be used to transmit the RS for P2 or P3, the gNB may indicate to the relay the actual beam index as described above, and may provide additional information to indicate whether the indicated beam should be applied exactly or an associated beam having common characteristics with the beam to be used for forwarding the RS may be used. The gNB may indicate to the relay which common characteristics should be maintained between the actually indicated beam and the beam used to forward the RS for P2 or P3.

Fig. 14 illustrates a beam indication and its characteristics 1400 according to an embodiment. Specifically, fig. 14 shows an example of a 5-bit field, where the 4 most significant bits 1401-1404 indicate the actual beam and the least significant bit 1405 indicates how the beam is applied. The b0 bit 1405 can indicate whether the actual beam is applied as it is, e.g., it is set to zero, which is beneficial in case of forwarding the RS for the P3 procedure.

On the other hand, if the b0 bit 1405 is set to 1, the repeater can determine to forward the beam so that it has some common characteristics with the actual beam indicated by the 4 most significant bits 1401-1404, which is beneficial for forwarding the RS for P2, as shown. The common characteristics may be predefined, i.e. provided in the specification, or configured to the relay by higher layer signaling, such as RRC or MAC-CE. For example, the gNB may configure the characteristic as QCL-type D. In this case, the repeater should ensure that the indicated actual beam can be considered as source QCL-type D from the UE perspective of the constructed forward beam.

Fig. 15 illustrates a beam and QCL type indication 1500 according to an embodiment. That is, the 2-bit field 1505, 1506 may indicate a relationship between the indicated actual beam and the beam constructed to forward the RS for P2 or P3. Specifically, the 2-bit field may indicate the QCL type that the relay should reserve between the indicated actual beam and the constructed beam. In other words, from the UE's point of view, the actual beams indicated by the most significant bits 1501, 1502, 1503, 1504, and the constructed beams should have QCL types indicated by the least significant bits 1505, 1506. Each code point may indicate a particular QCL type from the types { a, B, C, D }. Further, the gNB may configure a subset of QCL types that may be indicated, and the bit width of the field is determined accordingly.

These fields, which indicate the beam and additional information for the relationship between the indicated actual beam and the constructed beam, may be part of DCI, MAC-CE or RRC, depending on how the indication is provided from the gNB to the relay.

Although the previous examples describe the gNB indicating to the relay the actual beam to be used as a reference beam to determine the forward beam, the gNB may alternatively indicate the SSB Id, CSI-RS Id, and/or corresponding resource set Id, as described above. Specifically, the relay is expected to determine a new forwarding beam using a previously used beam of the SSB or CSI-RS for the forwarding indication as a reference beam.

Fig. 16 shows an indicator 1600 for a P2 or P3 procedure according to an embodiment. The indicator in fig. 16 is from the gNB to the repeater. The destination field 1601 indicates that the indicated CSI-RS is used for a P3 or P2 procedure. Another field 1602 shows the beams that the repeater should apply at their time positions (as indicated by the time domain bitmap field 1603) when forwarding all CSI-RSs with the first NZP-CSI-RS-resource set (with the repetition set to on or off). Another field 1604 shows a beam indication of the CSI-RS belonging to the second (i.e., next) NZP-CSI-RS-resource set (where the repetition is set to on or off), and a time domain indication of the CSI-RS is indicated by field 1605.

For DCI or MAC-CE based indications, the number of bitmaps to be included in the DCI may be indicated by higher layer signaling or may be predefined. Since some bitmaps may not be used each time, a special value may be indicated to inform the relay that the bitmaps are not used while keeping the DCI payload size fixed. For example, all zeros may be used as special values.

For RRC or MAC-CE based indications, the beam indication field and the time indication field may form a tuple (i.e., beam index, time information) that is transmitted from the gNB to the relay so that the relay knows at which time domain resources which beam should be applied. Based on fig. 16, two tuples (beam index (1602), time information (1603)), (beam index (1604), time information (1605)) can be indicated. Furthermore, each tuple may have a specific index that may be configured by RRC. In this case, for periodic beam indication by RRC, the gNB may indicate the applicable tuple (or tuples) to the repeater in each period. In the case of transmitting beam information from the gNB to the relay using a MAC-CE, the MAC-CE may indicate a single or multiple tuple index of those configured by RRC.

Fig. 17 shows P2 and P3 processes 1700 according to an embodiment. In particular, fig. 17 shows the overall process of P2 and P3, which is an extension of fig. 10, with some modifications.

Specifically, in step 4, repeater 1715 forwards four CSI-RSs { CSI-RS #x, CSI-RS #y, CSI-RS #z, CSI-RS #w } belonging to NZP-CSI-RS-resource set, with the repetition set to off. In this case, the repeater 1715 applies different beamforming for each CSI-RS, and one-to-one mapping is assumed, but other mapping procedures can be applied.

In step 5, the gNB 1705 may request the relay 1715 to provide the gNB 1705 with information on how CSI-RS are mapped to the actual beam by the relay 1715.

In step 6, relay 1715 provides information to gNB 1705 how CSI-RS maps.

After the legacy procedure, the UE 1710 measures the beam quality and reports an indicated metric, e.g., L1-RSRP, which is forwarded by the relay 1715 to the gNB 1705, as shown in step 7.

In step 8, the P3 procedure in beam management begins, where the gNB 1705 indicates to the relay 1715 the purpose of CSI-RS, which beams the relay 1715 should apply for each NZP-CSI-RS-resource set to repeat on, as shown in step 9.

The repeater knows the CSI-RS configuration of its UE

To perform beam refinement on the repeater-UE link, the repeater may attempt to detect/decode the signal/channel to be sent to the UE. This may be beneficial because the repeater knows the CSI-RS configuration sent from the gNB to the UE. In other words, the repeater attempts to understand the configuration of the UE and act accordingly to perform beam management when forwarding the RS.

This is beneficial because no additional signaling is required to complete the beam management procedures P2 and P3, and this is reasonable because the repeater on the gNB-repeater can be considered a typical UE. However, as the number of UEs served by the repeater increases, the complexity of repeater implementation increases. Thus, it is beneficial for the repeater to indicate to the gNB the maximum number of UEs that the repeater can use this mode for service through capability signaling. Such capability signaling may be similar to the capability signaling sent by the UE.

In order for the repeater to be able to decode the CSI-RS configuration and to know when the CSI-RS is triggered or activated, the repeater should decode the transmission before forwarding such transmission to the UE. Thus, the relay should be aware of the different scrambled RNTIs, e.g., C-RNTIs, for its UEs. In this way, the gNB may provide the RNTI of the UE within its coverage area to the relay through higher layer signaling such as RRC or MAC-CE.

Once the repeater receives such information, the repeater can decode the CSI-RS configurations of these UEs and monitor when they are (de) activated/triggered and act accordingly.

Alternatively, to reduce repeater complexity and avoid forcing the repeater to decode each transmission of a UE served by the repeater, the gNB may provide the repeater with a lumped (signed) configuration for each UE to be served by the repeater. Such information may be provided by higher layer signaling dedicated to the repeater.

For periodic CSI-RS in P2 or P3 procedure, i.e. CSI-RS belonging to NZP-CSI-RS-resource set that are repeatedly set to off or on, the relay knows when they will be transmitted. An unclear question is how the relay interprets the RRC parameter qcl-info periodic csi-RS. In conventional NR, QCL-InfoPeriodacCSI-RS points to a reference signal used as a source RS for providing QCL hypotheses to the UE when the UE is directly connected to the gNB.

For example, the repeater may interpret the RRC parameters qcl-infoperiodic csi-RS regarding the actual beam that the repeater builds on the repeater-UE link to forward the signal/channel of the gNB to the UE. In order for the gNB to know the actual beam constructed at the repeater, the above procedure of the repeater sending information on how some forwarded RSs are mapped to the actual beam may be used.

In the semi-persistent CSI-RS, a dedicated MAC-CE transmitted from the gNB to the relay may be used (the MAC-CE may be different from the MAC-CE to be transmitted to the UE). The MAC-CE may be similar to a conventional MAC-CE used to activate the semi-persistent CSI-RS, but may interpret the TCI status ID field for the actual beam constructed by the repeater, as described above.

In aperiodic CSI-RS, similar to DCI used in conventional NR, trigger DCI can be used to indicate to a relay which aperiodic CSI-RS to trigger (the DCI may be different from DCI to be transmitted to a UE). Similarly, the TCI field in the DCI may be interpreted with respect to the actual beam constructed by the repeater, as described above.

As described above, the repeater can directly interpret the provided TCI state ID using knowledge of the RS ID. Specifically, the repeater constructs the retransmission beam such that, from the perspective of the UE, the retransmission beam and the beam used as the source RS in the provided TCI have common characteristics based on the directions indicated by the QCL types { a, B, C, D }.

Fig. 18 illustrates TCI status indications for a forwarding beam 1800 according to an embodiment. Specifically, fig. 18 shows an example of how a repeater can interpret TCI states indicated in the time domain.

In step 1, the repeater forwards ssb#0 and builds a particular beam, e.g., beam 1 1801. In step 2, the repeater forwards CSI-RS #4 and knows its ID (the repeater knows that it is forwarding CSI-RS # 4). The gNB provides the relay with a TCI status ID indicating SSB#0 as a reference RS and a particular QCL type. In this case, the repeater constructs a retransmission beam 2 1802 of the CSI-RS #4 based on a beam 1 1801 for retransmitting SSB #0 such that the received CSI-RS #4 and SSB #0 are QCL with respect to the indicated type from the perspective of the UE.

In step 3, the gNB instructs the relay to forward some transmissions that are not known to the relay, instructs the forwarding duration and instructs the applicable TCI state ID, which indicates the CSI-RS and the specific QCL type as reference RS. In this case, the repeater constructs a forwarding beam of the DL transmission based on the beam for forwarding the CSI-rs#4 such that the received DL transmission (e.g., DMRS of the transmission) and the CSI-rs#4 are QCL with respect to the indicated type from the perspective of the UE.

The legacy TCI framework can be extended so that the repeater can use the framework to construct a forward beam based on the beam used to forward the reference RS with respect to a particular QCL type.

For example, the gNB may configure the TCI status pool for the relay via higher layer signaling (e.g., RRC only or RRC+MAC-CE). The TCI state pool may be different from the TCI state pool configured by the mobile portion of the repeater. To distinguish between the two pools, higher layer parameters, e.g., within the TCI state IE, may indicate whether the configuration pool is for the mobile part of the repeater, for the forwarding link, or for defining a new TCI IE for the forwarding link.

Each TCI state in the TCI pool indicates a reference RS (or more) and an applicable QCL type(s). In this case, the repeater constructs the retransmission beam such that the beam has a common QCL type (or types) with an earlier beam of the source RS used as an indication from the perspective of the UE. The repeater should know the ID of the forwarded RS, which can be done as described above or by any other procedure.

From this TCI pool, gNB can (de) activate a subset of the TCI states. The new MAC-CE may be used to indicate a TCI state that may be used to indicate (de) activation of the forwarding beam. Alternatively, the same MAC-CE used to (de) activate the TCI state of the mobile part of the repeater may be used.

To determine the TCI pool from which the active TCI state is activated, a 1-bit field in the MAC-CE may be used. For example, if the 1-bit field is set to zero or 1, the MAC-CE activates (deactivates) the mobile part of the repeater or the TCI state of the forwarding link, respectively. For example, in "enhanced TCI state activation/deactivation for UE-specific PDSCH MAC-CE", there is one reserved bit that can be used for this purpose. Furthermore, in "TCI state activation/deactivation for UE specific PDSCH MAC CE", the number of TCI states configured by RRC should not be an integer multiple of 8, such that at least the remaining 1-bit field indicates which TCI state pool should be used.

Thereafter, the DCI may be used to indicate the applicable TCI status in addition to other information such as the duration of the repeater forward transmission.

To reduce signaling overhead, a single TCI state pool may be configured to the mobile part of the repeater or the forwarding link. In this case, the indicated source RS is expected to be received by the mobile part of the relay so that the receiver knows its ID, time position, etc. Further, the source RS is forwarded on the forwarding link such that the repeater can determine a subsequent forwarding beam based on the earlier beam used to forward the source RS. In this case, a legacy MAC-CE may be used to activate a subset of the TCI states of both the mobile part of the repeater and the forwarding link. Furthermore, separate MAC-CEs may be used as described previously to separate the mobile part of the repeater and the subset of active TCI states of the forwarding links.

Beam aspect for scheduling (PDSCH/PDCCH/PUSCH/PUCCH)

The repeater is unaware of the configuration of its UE

In addition to forwarding the RS for different purposes, the relay may also forward different DL or UL channels. Assuming that the repeater does not know the configuration of the DL or UL channels, the repeater cannot determine which beam should be used to transmit to/receive from the UE on the repeater-UE link.

Although different embodiments are described herein with reference to DL channels (PDSCH/PDCCH), the present disclosure is not limited thereto and can be extended for UL channels (PUSCH/PUCCH).

In general, a relay may not know whether it forwards PDCCH or PDSCH. The repeater should know the OFDM symbol spanned by the channel to be forwarded or which actual beam should be applied.

To support dynamic scheduling, an indication from the gNB to the relay can be provided in the form of DCI on a PDCCH with a CRC that is scrambled by the RNTI of the relay on the gNB-relay link. The RNTI can be similar to the C-RNTI of a typical UE. In this case, the repeater may have at least two RNTIs, one of which may be used to scramble DCI carrying beam information from the gNB to the repeater, and another used similarly to a typical UE, such as a C-RNTI for receiving a dedicated configuration. The conventional method of configuring SS sets and CORESET for a typical UE may be applied to a repeater.

The indication may carry information in the form of information carried in the CSI-RS framework. The same bit map framework disclosed for CSI-RS may be used for the P3 procedure, as shown in fig. 16. In particular, one bitmap may be used to indicate symbols for PDCCHs to be forwarded on the relay-UE link, while another bitmap is used to indicate symbols for PDSCH to be forwarded on the relay-UE link. Each bitmap may be associated with a field indicating which actual beam or TCI state the relay should use to forward the PDCCH or PDSCH based on how the relay maps CSI-RS for P2 to the actual beam as shown in fig. 11 or any other method for informing the gNB of the index of the actual beam on the relay-UE link.

Since PDCCH and PDSCH are contiguous in the time domain, using SLIV to indicate occupied OFDM symbols may be more advantageous to reduce overhead. The DCI may directly carry the SLIV values, or several SLIV values (e.g. 16 values) may be configured and the DCI only points to which row is to be applied. The value of the SLIV may be similar to a conventional Time Domain Resource Allocation (TDRA) table configured by RRC, where a list is provided to the relay and each entry in the relay may have an index of the entry and a start slot, which can be defined as offset and can be relative to the DCI carrying the indication, or can be relative to the period if RRC or MAC-CE is used to carry the indication. Instead of configuring a starting slot for each entry, a common offset relative to DCI/RRC/MAC-CE may carry the indication. The common offset may be configured, predefined (i.e., provided in the specification), or similar to the applicability time described herein based on the processing power of the mobile portion of the repeater (processing power 1 or 2) or the timeduration forqcl indicated by the mobile portion of the repeater. The predefined offset may be the first time slot in each period for periodic or semi-persistent beam indication by RRC or MAC-CE.

Another offset can be configured or predefined to indicate a start symbol within the indicated slot. For example, a predefined start symbol, e.g., symbol #0, is applied in the indicated slot. Both the start symbol and the duration in symbols can be jointly encoded, and a single value of the SLIV can indicate both the start symbol and the duration of the slot indicated by the repeater application. Alternatively, the start symbol and the duration can be encoded separately. That is, the RRC can configure separate values of the start symbol and duration by separate RRC parameters to provide greater flexibility to the gNB.

Fig. 19 illustrates a SLIV method 1900 of indicating DL forwarding locations and corresponding beams according to an embodiment. Specifically, fig. 19 shows an example of indicating the time domain locations of PDCCH/PDSCH and their corresponding beams using a SLIV-based method.

In fig. 19, similar to fig. 16, DCI 1901 carrying an indication from the gNB to the relay may have multiple fields carrying the SLIV values and their associated beam information, i.e., the one-to-one association between the time indication field and the beam indication field of PDCCH 1902/PDSCH 1903 that the relay should use to forward. To keep the DCI payload fixed, the number of SLIV fields and their corresponding beam indication fields may be configured by higher layer signaling or may be predefined. Since some SLIVs may not be used each time, e.g., SLIV #3 1904, a special value may be indicated to inform the repeater that SLIV #3 1904 is not used, while keeping the DCI payload size fixed. For example, all zeros may be used as special values. Similarly, a special value of the beam indication field can be reserved to indicate to the repeater that this field and its associated time indication field can be ignored, so that all zeros can be used as special values.

Instead of having a SLIV value field for each indicated beam, a single SLIV value may be indicated by a single slot offset, symbol offset, and duration. In this case, the repeater may use the indicated start symbol to apply to the first indicated beam. The indicated duration may be assumed to be the total duration of all indicated beams and the duration of each beam may be derived according to a rule, e.g. it may be equally divided over the beams. For example, if the indicated duration is 25 symbols and 4 beams are indicated, the first three indicated beams, e.g., indicated by the most significant bits, are applied for the duration of [25/4] or [25/4] symbols, and the last indicated beam, e.g., indicated by the least significant bits, is applied for the remaining duration. Another possibility is that the repeater applies a single indicated duration to each indicated beam. Once the duration of each indicated beam is determined, the repeater can determine the starting time position of the subsequent indicated beam so that they can be applied back-to-back.

The indication can also be carried by the MAC-CE or RRC.

This embodiment can be equally applied to CSI-RS in P3 or P2 procedures.

Since the indication from the gNB to the relay may be in several procedures, e.g., CSI-RS in P2 procedure, CSI-RS in P3 procedure, and PDCCH/PDSCH indication, the destination field may be used to indicate how the relay interprets the indication.

Table 4 below shows an example of a destination field for different procedures, where the destination field is extended to include other purposes for forwarding PDCCH/PDSCH/PUCCH/PUSCH.

TABLE 4 Table 4

For the indication carried by DCI, a different RNTI can be used instead of having a destination field. In particular, the gNB may configure different RNTIs for the relay, such as P1-RNTI, P2-RNTI, DL-CH-RNTI and UL-CH-RNTI. In this case, the repeater may need to apply a different scrambling ID to determine how the indication should be interpreted.

While carrying this indication in DCI is beneficial for dynamic scheduling, this can result in high signaling overhead and power consumption at the repeater. Thus, the indication may be sent through higher layer signaling (e.g., MAC-CE or RRC), which may be beneficial for semi-persistent or periodic transmissions. The solution may be similar to the aforementioned procedure for CSI-RS for P2 and P3.

In addition, higher layer signaling, such as RRC or MAC-CE, may indicate multiple SLIVs with a particular period and their associated beams. The pattern may repeat itself continuously until it is deactivated or released. The periodicity may be the same as the periodicity of a semi-persistent scheduling (SPS) PDSCH of an SS, CSI-RS, etc.

When the indication is carried from the gNB to the relay using the MAC-CE, the relay can apply the proposed after the relay sends the HARQ-Ack of the MAC-CEFor indication. For example, it may be in time slotsThe indication is applied in the first time slot thereafter, where n is the time slot of the HARQ-Ack for the MAC-CE.

In case of using RRC, the specific offset to which the indicator is applied may be signaled or predefined by higher layer signaling or according to some rules as in the case of MAC-CE.

Prioritization of priority

In practice, the gNB may use multiple indication procedures (in DCI, in MAC-CE or in RRC) to indicate to the relay which symbols/slots to forward and which beam should be used. However, collisions may occur for sets of symbols/slots. For example, if the gNB indicates to the repeater that a particular beam is used on a set of symbols by higher layer signaling and then indicates to use another beam for the same set of symbols, then it may be necessary to define the repeater's behavior to avoid confusion at the UE side. There may be partial or complete overlap in the time domain between the durations indicated for the different beam indications. Such a procedure would be beneficial to provide sufficient flexibility for the gNB and preserve legacy functionality in the NR. For example, the gNB may want to cancel a configured DL transmission of a particular UE associated with a particular beam on the repeater-UE link and send a higher priority transmission to another UE that needs a different beam.

For example, the indication carried by the DCI may cover the indication by the MAC-CE, which may cover the indication by the RRC, i.e. DCI > MAC-CE > RRC in terms of priority. When a collision occurs, the repeater may apply an indication provided by the highest priority signaling (i.e., DCI, MAC-CE, or RRC). Furthermore, the priority may be opposite, i.e. RRC > MAC-CE > DCI, which is advantageous because RRC may be used to indicate a cell specific signal/channel.

Fig. 20 illustrates a handling 2000 of a collision between indications provided by RRC and DCI according to an embodiment. Specifically, in slot 2 2003, the set of symbols indicated by RRC 2001 to be forwarded using beam 3 2005 overlaps with the set of symbols indicated by DCI 2002 to be forwarded using beam 2 2004. In this case, the repeater may apply beam 2 2004 based on the DCI indication and may forward any symbols in another set without using beam 3 2005. Alternatively, beam 2 2004 is used for only overlapping symbols, but the repeater may still forward the remaining symbols using beam 3 2005.

A symbol set may be defined as a symbol indicated by one SLIV value or by one bitmap.

A collision may occur between different indicators provided by the same signaling (i.e., DCI, MAC-CE or RRC) or different signaling. One possibility to solve this problem is that the repeater may apply the most recently received indication. Alternatively, a priority field may be included in the indication to indicate its associated priority. An additional field for priority may be included for an indication of the use of the PDCCH. This may be a single priority field indicating the priorities of all beams indicated by the PDCCH, or a separate priority field for each indicated beam. Similarly, for beam indication using MAC-CE or RRC, a single priority field indicating the priority of all beams indicated by MAC-CE or RRC, or a separate priority field for each indicated beam or beam and tuple of time indications may be used. For example, two priority levels may be included in the indication corresponding to the low priority and the high priority. In case of a collision, the repeater application has the indication of the highest priority.

To simplify repeater implementation, such restrictions may be imposed: no collision is expected to occur between indicators sent by the same signaling or by different signaling.

Default beam

The repeater may not receive an indication from the gNB indicating which beams should be applied on the symbol/slot set on the repeater-UE link. It would therefore be beneficial to define which beam the repeater should select for this set of symbols/slots.

For example, the gNB may explicitly indicate to the relay which beam on the relay-UE link should be used as the default beam. In this case, the gNB may rely on mapping information provided to the gNB from the repeater, for example, as shown in fig. 11.

The gNB may indicate to the gNB from the repeater a set of multiple ones of those beams indicated in the mapping information as default beams. In this case, the default beam may be constructed as a beam covering the same spatial direction of all beams in the indicated set.

The default beam for forwarding transmissions on the repeater-UE link may be determined according to some rules. For example, the default beam may have the same spatial direction as the first m beams indicated in the mapping information from the repeater to the gNB, as shown in fig. 11. The value of m may be subject to repeater capability, which may be reported from the repeater to the gNB as part of its capability signaling. Further, the repeater may indicate multiple m values, and the gNB may select one value.

Alternatively, the repeater may use the same beam used to forward the SSB. For example, if the repeater receives an SSB (or decides to forward an SSB on the repeater-UE link), the repeater applies the same beam to the set of symbols/slots for forwarding the SSB without an indication of the beam to be applied.

As another possibility, the default beam may be the last indicated beam.

The different solutions disclosed for indicating CSI-RS or different channels can be applied interchangeably.

The repeater knows the configuration of its UE

Similar to the case of CSI-RS, when the repeater knows the configuration of its own UE, the repeater can attempt to detect/decode the signal/channel to be sent to the UE. The same procedure disclosed for CSI-RS can be extended for different DL/UL channels.

If the gNB provides the repeater with an aggregated configuration for each UE to be served by the repeater, e.g., PDSCH-Config for each UE, some modification of the configured TCI-State may be required so that the repeater knows which beam should be used to forward the transmission from the gNB to the UE.

For example, the repeater may interpret the RRC parameter preferenceign with respect to the actual beam that the repeater builds on the repeater-UE link to forward the signal/channel of the gNB to the UE. In order for the gNB to know the actual beam constructed at the repeater, the above procedure in which the repeater sends information about how some forwarded RSs are mapped to the actual beam can be applied.

Beam fault recovery

As part of beam fault recovery, the UE should evaluate the quality of the serving beam and identify candidate beams for recovery. To this end, multiple sets of periodic RSs can be configured to detect beam faults and identify candidate beams. In the case of single Transmission and Reception Point (TRP) operation, respectively configuringAnd->In the case of a plurality of TRPs, respectively configureAnd->

Thus, from the aspect that the repeater can know when these RSs should be transmitted and which beam should be applied, these RSs can be considered as CSI-RSs for the P3 procedure. That is, the repeater cannot freely select the actual beam on the repeater-UE link, similar to the case of CSI-RS for the P2 procedure, as this would result in the unnecessary triggering of the beam-failure recovery procedure.

Thus, the above procedure can be applied to inform the relay when to transmit such CSI-RS and which beam should be applied.

Beam for gNB repeater forward link

The gNB repeater link consists of two links, link 1 (gNB to repeater mobile part) between the gNB and the mobile part of the repeater, which can be considered a typical UE connected to the gNB. The link is mainly used to enable the gNB to control the forwarding link. Link 2 (backhaul) is between the gNB and the forwarding unit of the relay and is used to receive or transmit DL or UL transmissions from the gNB or UE to be forwarded to the UE or gNB, respectively.

On link 1, conventional beam management techniques may be used to indicate to the mobile part of the repeater which beam should be used for reception or transmission. An additional procedure may be required for link 2 to the repeater to determine which beam should be used for transmission or reception. That is, for communication on link 1, there can be multiple beams for different channels (such as PDCCH and PDSCH), and it is unclear which beam can be directly applied to link 2.

One possibility is to indicate which beam should be used for reception or transmission of link 2 with the beam configuration corresponding to link 1. In this case, the same configured TCI state pool may be used for both links.

From this TCI pool, the gNB may individually (de) activate a subset of the TCI states for each link. The new MAC-CE may be used to indicate the (de) active TCI state, which may be used to indicate the (de) active beam for link 2 (backhaul). Alternatively, the same MAC-CE may be used to (de) activate the TCI state of both links.

To determine the applicable link, a 1-bit field in the MAC-CE may be used for this purpose. For example, if it is set to zero or 1, the MAC-CE activates (deactivates) the TCI state of link 1 or link 2, respectively. For example, in "enhanced TCI state activation/deactivation for UE-specific PDSCH MAC-CE" there is one reserved bit that can be used for this purpose. Furthermore, in "TCI state activation/deactivation for UE specific PDSCH MAC CE", the number of TCI states of RRC configuration should not be an integer multiple of 8, such that at least a 1-bit field is left for an applicable link.

The same concept can be extended when RRC configures separate TCI state pools for link 1 and link 2. In this case, the above procedure may be applied to (de) activate a subset of TCI states to indicate which TCI state pool to use.

Except for the beam that indicates that the repeater should use on link 2, the repeater does not know how long and when it should use the beam. Thus, the repeater may employ the provided timing information for forwarding on the repeater-UE link. That is, link 2 and the repeater-UE link may be coupled together. In this case, it may be assumed that the duration indicated for the relay-UE link is the same as the duration of link 2.

It is beneficial to have a collective indication of at least one of the following: the time domain indication of the forwarding duration on link 2 and the relay-UE link, the beam information for the relay-UE link as described herein, which may include the actual TCI state and common characteristics (such as QCL type { a, B, C, D }) between the beams for the forwarding source RS, and the beam information for link 2 based on the beam configuration of the mobile portion of the relay as described herein, are indicated using any of the above processes.

Such collective information may be provided via RRC, MAC-CE, or DCI as described herein.

While the beam of link 2 may be based on the beam configuration of the mobile part of the repeater, the gNB and the repeater may use a method similar to the beam indication of the repeater-UE link. This may be beneficial when the mobile part of the repeater is in a different frequency band than link 2. In this case, the repeater and the gNB may communicate to determine the actual beam used to receive or transmit the different reference signals on link 2 and indicate what beam should be applied in subsequent reception or transmission on link 2.

Although described herein as providing collective information for link 2 and the repeater-UE link, the information for link 2 may also be provided separately, which may provide greater flexibility for the gNB to change the beams of the different links.

Further, a default beam may be defined for link 2, similar to the default beam of the repeater-UE link, which is used in the absence of an indication of which beam should be used. In addition, on link 2, the repeater may use the latest beam for transmission or reception of the mobile part of the repeater.

Throughout this disclosure, DCI is described to carry different indications, such as applicable beams, duration of forwarding using the beams, etc.

A new DCI format is introduced for this purpose. In this case, the mobile part of the repeater may receive a new DCI format carrying side control information as described herein to define how the forwarding occurs in terms of duration and applied beam. The DCI may be scrambled with a specific RNTI similar to the C-RNTI.

If separate DCIs are used to carry control information for link 2 and the repeater-UE link, each DCI may have a different RNTI or a bit field having a bit width of 2 bits can be used to indicate the applicable instruction for at least one of the link 2 and the repeater-UE link.

Another possibility is to use an existing DCI format, where some existing fields are re-interpreted, reserved or ignored by the mobile part of the relay. For example, the TCI field may be used to indicate the beam that the relay should use to forward the transmission on link 2 or the relay-UE link. Further, the time domain resource allocation field can be used for a SLIV indicating a forwarding duration as described herein, or can be combined with other fields such as a frequency hopping flag, MCS, NDI, or RV to construct a larger field indicating duration in the form of a bitmap for forwarding different transmissions. Other fields may be omitted.

In order for this method to work, the relay should know how to interpret the DCI, e.g. a periodically scheduled DCI that schedules PDSCH carrying MAC-CE, or a DCI that provides direct instructions on how forwarding should be done. To this end, the gNB may configure a separate search space/CORESET such that there is no ambiguity, and this may be indicated by higher layer signaling (e.g., RRC parameters). In this case, PDCCH monitoring opportunities (by periodically scheduling DCI and DCI carrying direct instructions) may not overlap.

Solutions are disclosed that indicate the time domain in which forwarding occurs in link 2 or a relay-UE link, e.g., based on bitmaps, SLIVs, etc. To reduce signaling overhead, a certain value may be reserved to indicate that the indicated beam may be applied until other beam indications are received. However, when using concepts similar to the unified TCI framework, time domain indications may not be needed. In this case, it may be sufficient to indicate the beam to be used on link 2 and the repeater-UE link.

For example, if the mobile part of the repeater is configured to use a unified TCI state framework, the repeater may assume that the same indicated beam on link 1 may be applied to link 2, at least for cells in the same frequency band as the operating frequency band of the mobile part of the repeater. In general, link 1 may operate using a unified TCI state framework, while link 2 needs to indicate duration. Thus, it would be beneficial for the gNB to explicitly indicate whether link 2 uses a unified TCI status framework (e.g., via higher layer signaling), or to implicitly indicate this by instructing the repeater to continue using the same beam on the repeater-UE link until the next beam indication is received (e.g., leaving some value in the time indication field for this purpose).

If link 2 uses a unified TCI state framework, this does not necessarily mean that the unified TCI state framework is automatically applied to the beams of the repeater-UE link. That is, some UEs served by the repeater may operate using a conventional TCI framework. Even though all UEs served by the repeater use a unified TCI state framework, it is desirable that they use different beams. Thus, the gNB may explicitly indicate whether the unified TCI state framework should be applied over the relay-UE link, e.g., via higher layer signaling. Alternatively, the gNB may implicitly indicate this by instructing the relay to keep using the same beam on the relay-UE link until the next beam indication is received, e.g. a certain value is reserved in the time indication field for this purpose.

As another possibility for indicating an applicable beam, the gNB and the repeater may not need to exchange information about the actual beam or the reference signal ID. The gNB and the repeater may determine a particular time window that can be used to indicate which beam the repeater should apply. There may be two time windows, one for the repeater-UE link and one for link 2. The determination of the window may include indicating its start and length, which can employ granularity of OFDM symbols, slots, subframes, frames, etc., or by indicating an index of the first/last OFDM symbol, slot, subframe, frame, etc. in the window. The gNB may dynamically provide configuration of such windows through higher layer signaling such as RRC, MAC-CE, or even through DCI.

This window is then used to indicate which beam should be used by the relay to forward different transmissions on the relay-UE link or link 2. In particular, to indicate a particular beam on the relay-UE link, link 2, or both, the gNB may indicate a particular instance of time in the window. In this case, the repeater applies the same beam in the window as was used in the indicated time instance.

To indicate a time instance, a bitmap may be used in which each bit may be mapped to a single OFDM symbol, slot, subframe, frame, etc. within a time window, or even each bit may correspond to a plurality of OFDM symbols, slots, subframes, frames, etc. within a time window.

The time instance may also be provided to the repeater by an index indicating an OFDM symbol, slot, subframe, radio frame, etc. within the time window.

Other solutions in the present disclosure can be combined to have a complete framework. For example, the above-described method for indicating the relationship between two beams (the beam in the time window and the new beam constructed by the repeater), such as the QCL type between the two beams, may also be used. The above-described method for indicating when and for how long the indicated beam will be applied can also be used.

Fig. 21 is a block diagram of an electronic device in a network environment 2100, according to an embodiment. Referring to fig. 21, an electronic device 2101 in a network environment 2100 can communicate with an electronic device 2102 via a first network 2198 (e.g., a short-range wireless communication network) or with an electronic device 2104 or server 2108 via a second network 2199 (e.g., a long-range wireless communication network), and can also communicate with a repeater (such as repeater 200 in fig. 2) as described throughout this specification. The electronic device 2101 may communicate with the electronic device 2104 via a server 2108. The electronic device 2101 may include a processor 2120, a memory 2130, an input device 2140, a sound output device 2155, a display device 2160, an audio module 2170, a sensor module 2176, an interface 2177, a haptic module 2179, a camera module 2180, a power management module 2188, a battery 2189, a communication module 2190, a Subscriber Identity Module (SIM) card 2196, or an antenna module 2194. In one embodiment, at least one of the components (e.g., display device 2160 or camera module 2180) may be omitted from electronic device 2101, or one or more other components may be added to electronic device 2101. Some components may be implemented as a single Integrated Circuit (IC). For example, sensor module 2176 (e.g., a fingerprint sensor, iris sensor, or illuminance sensor) may be embedded in display device 2160 (e.g., a display).

The processor 2120 may execute, for example, software (e.g., program 2140) to control at least one other component (e.g., hardware or software component) of the electronic device 2101 coupled to the processor 2120 and may perform various data processing or computation. As at least part of the data processing or calculation, the processor 2120 may load commands or data received from another component (e.g., the sensor module 2146 or the communication module 2190) into the volatile memory 2132, process the commands or data stored in the volatile memory 2132, and store the resulting data in the nonvolatile memory 2134. The processors 2120 may include a main processor 2121 (e.g., a Central Processing Unit (CPU) or an Application Processor (AP)) and an auxiliary processor 2123 (e.g., a Graphics Processing Unit (GPU), an Image Signal Processor (ISP), a sensor hub processor, or a Communication Processor (CP)), the auxiliary processor 2123 being operable independent of the main processor 2121 or in conjunction with the main processor 2121. Additionally or alternatively, the secondary processor 2123 may be adapted to consume less power than the primary processor 2121 or perform certain functions. The secondary processor 2123 may be implemented separately from the primary processor 2121 or as part of the primary processor 2121.

The secondary processor 2123 may replace the primary processor 2121 while the primary processor 2121 is in an inactive (e.g., sleep) state, or control at least some of the functions or states associated with at least one of the components of the electronic device 2101 (e.g., the display device 2160, the sensor module 2176, or the communication module 2190) with the primary processor 2121 while the primary processor 2121 is in an active state (e.g., executing an application). The auxiliary processor 2123 (e.g., an image signal processor or a communication processor) may be implemented as part of another component (e.g., a camera module 2180 or a communication module 2190) functionally related to the auxiliary processor 2123.

The memory 2130 may store various data used by at least one component of the electronic device 2101 (e.g., the processor 2120 or the sensor module 2176). The various data may include, for example, software (e.g., program 2140) and input data or output data for commands associated therewith. Memory 2130 may include volatile memory 2132 or nonvolatile memory 2134.

Programs 2140 may be stored as software in memory 2130 and may include, for example, an Operating System (OS) 2142, middleware 2144, or applications 2146.

The input device 2150 may receive commands or data from outside the electronic device 2101 (e.g., a user) to be used by another component of the electronic device 2101 (e.g., the processor 2120). Input device 2150 may include, for example, a microphone, a mouse, or a keyboard.

The sound output device 2155 may output sound signals to the outside of the electronic device 2101. The sound output device 2155 may include, for example, a speaker or receiver. The speaker may be used for general purposes, such as playing multimedia or recording, and the receiver may be used to receive incoming calls. The receiver may be implemented separately from the speaker or as part of the speaker.

The display device 2160 may visually provide information to an exterior (e.g., a user) of the electronic device 2101. The display device 2160 may include, for example, a display, a hologram device, or a projector, and control circuitry for controlling a corresponding one of the display, hologram device, and projector. Display device 2160 may include touch circuitry adapted to detect touches or sensor circuitry (e.g., pressure sensors) adapted to measure the strength of forces caused by touches.

The audio module 2170 may convert sound into an electrical signal and vice versa. The audio module 2170 may obtain sound via the input device 2150 or output sound via the sound output device 2155 or headphones of the external electronic device 2102 that is directly (e.g., wired) or wirelessly coupled to the electronic device 2101.

The sensor module 2176 may detect an operational state (e.g., power or temperature) of the electronic device 2101 or an environmental state (e.g., a state of a user) external to the electronic device 2101 and then generate an electrical signal or data value corresponding to the detected state. The sensor module 2176 may include, for example, a gesture sensor, a gyroscope sensor, an atmospheric pressure sensor, a magnetic sensor, an acceleration sensor, a grip sensor, a proximity sensor, a color sensor, an Infrared (IR) sensor, a biometric sensor, a temperature sensor, a humidity sensor, or an illuminance sensor.

The interface 2177 may support one or more specified protocols for coupling the electronic device 2101 directly (e.g., wired) or wirelessly with the external electronic device 2102. The interface 2177 may include, for example, a High Definition Multimedia Interface (HDMI), a Universal Serial Bus (USB) interface, a Secure Digital (SD) card interface, or an audio interface.

The connection terminal 2178 may include a connector via which the electronic device 2101 may be physically connected with the external electronic device 2102. The connection terminal 2178 may include, for example, an HDMI connector, a USB connector, an SD card connector, or an audio connector (e.g., an earphone connector).

The haptic module 2179 may convert an electrical signal into a mechanical stimulus (e.g., vibration or movement) or an electrical stimulus that can be recognized by a user via a tactile or kinesthetic sensation. Haptic module 2179 may include, for example, a motor, a piezoelectric element, or an electro-stimulator.

The camera module 2180 may capture still images or moving images. The camera module 2180 may include one or more lenses, image sensors, image signal processors, or flash lamps.

The power management module 2188 may manage power supplied to the electronic device 2101. The power management module 2188 may be implemented as at least a portion of, for example, a Power Management Integrated Circuit (PMIC).

The battery 2189 may provide power to at least one component of the electronic device 2101. The battery 2189 may include, for example, a non-rechargeable primary battery, a rechargeable secondary battery, or a fuel cell.

The communication module 2190 may support establishing a direct (e.g., wired) communication channel or a wireless communication channel between the electronic device 2101 and an external electronic device (e.g., the electronic device 2102, the electronic device 2104, or the server 2108) and performing communication via the established communication channel. The communication module 2190 may include one or more communication processors that are operable independently of the processor 2120 (e.g., AP) and support direct (e.g., wired) or wireless communication. The communication modules 2190 may include wireless communication modules 2192 (e.g., cellular communication modules, short-range wireless communication modules, or Global Navigation Satellite System (GNSS) communication modules) or wired communication modules 2194 (e.g., local Area Network (LAN) communication modules or Power Line Communication (PLC) modules). A corresponding one of these communication modules may be via a first network 2198 (e.g., a short-range communication network such as Bluetooth ^TM Wireless fidelity (Wi-Fi) direct or infrared data association (IrDA) standard) or a second network 2199 (e.g., a long-range communication network such as a cellular network, the internet, or a computer network (e.g., a LAN or Wide Area Network (WAN)) with an external electronic device. These various types of communication modules may be implemented as a single component (e.g., a single IC), or may be implemented as multiple components (e.g., multiple ICs) separate from one another. The wireless communication module 2192 may use subscriber information (e.g., international Mobile Subscriber Identity (IMSI)) stored in the subscriber identification module 2196 to identify and authenticate the electronic device 2101 in a communication network (e.g., the first network 2198 or the second network 2199).

The antenna module 2197 may transmit signals or power to or receive signals or power from outside of the electronic device 2101 (e.g., an external electronic device). The antenna module 2197 may include one or more antennas, and from among these, at least one antenna suitable for a communication scheme used in a communication network, such as the first network 2198 or the second network 2199, may be selected, for example, by the communication module 2190 (e.g., the wireless communication module 2192). Signals or power may then be transmitted or received between the communication module 2190 and the external electronic device via the selected at least one antenna.

Commands or data may be sent or received between the electronic device 2101 and the external electronic device 2104 via a server 2108 coupled to the second network 2199. Each of the electronic devices 2102 and 2104 may be the same type of device as the electronic device 2101 or a different type of device. All or some of the operations to be performed at the electronic device 2101 may be performed at one or more of the external electronic devices 2102, 2104, or 2108. For example, if the electronic device 2101 performs a function or service automatically or in response to a request from a user or another device, the electronic device 2101 may request that one or more external electronic devices perform at least a portion of the function or service instead of performing the function or service, or the electronic device 2101 may request that one or more external electronic devices perform at least a portion of the function or service in addition to performing the function or service. The external electronic device or devices receiving the request may perform at least a portion of the requested function or service, or additional functions or additional services related to the request, and communicate the results of the execution to the electronic device 2101. The electronic device 2101 may provide the results as at least a portion of a reply to the request with or without further processing of the results. To this end, for example, cloud computing, distributed computing, or client-server computing techniques may be used.

Although the present disclosure has been described with reference to certain embodiments, various changes may be made without departing from the spirit and scope of the disclosure, which is defined not by the detailed description and embodiments but by the appended claims and their equivalents.

Claims (20)

1. A method of determining an access link beam by a repeater, comprising:

receiving an indication of a beam index from a base station, the indication of the beam index comprising a corresponding time of the indicated beam and the indicated beam applied; and

at least one set of resources is transmitted using the indicated beam.

2. The method according to claim 1,

wherein the at least one set of resources is transmitted to the user equipment.

3. The method according to claim 2,

wherein the corresponding time of the beam to which the indication is applied is signaled by a duration, a slot offset and a symbol offset.

4. A method according to claim 3,

wherein the indication of the beam index is received by the repeater via higher layer signaling that can additionally indicate the period.

5. A method according to claim 3,

wherein the indication of the beam index is received by the relay via downlink control information, DCI.

6. The method according to claim 5,

wherein the DCI includes a plurality of fields dedicated to indicate each beam.

7. The method according to claim 5,

wherein the DCI includes at least one field dedicated to a time position of a beam to which the indication is to be applied.

8. The method according to claim 7,

wherein, when a plurality of fields for beam indication and time indication are included in the DCI, each indicated beam is associated with a single time indicated by a corresponding time indication field.

9. The method according to claim 5,

wherein the indication of the beam index is transmitted to the relay through a radio network temporary identifier, RNTI, applied to the DCI, the RNTI being different from RNTIs used for receiving other configurations.

10. The method of claim 4, further comprising:

when the higher layer signaling is a radio resource control RRC or medium access control-control element MAC-CE spanning the indicated period, the indicated beam and corresponding time resource are repeated.

11. The method of claim 5, further comprising:

when the beam indication by DCI collides with the beam indication by radio resource control RRC, the beam indication by DCI is prioritized over the semi-static beam indication by RRC.

12. A method of a repeater, comprising:

receiving a downlink transmission from a base station;

selecting a backhaul beam from a same transmission configuration indicator, TCI, status pool for a control link between a base station and a mobile terminal of a relay based on an indication received from the base station; and

the downlink transmission is forwarded to the user equipment UE.

13. The method of claim 12, further comprising:

the state of the TCI state pool for the backhaul link is activated via the medium access control-control element MAC-CE.

14. The method of claim 13, further comprising:

the default beam is applied in the absence of a backhaul beam indication from the base station.

15. The method according to claim 14,

wherein when the unified TCI state framework is applied, the same beam for the link between the base station and the mobile terminal of the receiver is applied to the backhaul link.

16. An apparatus, comprising:

at least one processor; and

at least one memory operably connected to the at least one processor, the at least one memory storing instructions that, when executed, instruct the at least one processor to perform the method of a repeater by:

Receiving an indication from the base station for determining which beam to apply on the access link and the backhaul link;

applying the indicated beam to forward the transmission to the user equipment UE;

receiving a downlink transmission from a base station; and

the downlink transmission is forwarded to the UE.

17. The apparatus according to claim 16,

wherein the instructions further instruct the at least one processor to determine a beam to use on the access link and a corresponding applicable time based on the instructions received via DCI, MAC-CE or RRC.

18. An apparatus according to claim 17,

wherein the instructions further instruct the at least one processor to: when the beam indication by DCI collides with the beam indication by radio resource control RRC, the beam indication received via DCI is prioritized over the semi-static beam indication by RRC.

19. The apparatus according to claim 16,

wherein the instructions further instruct the at least one processor to select a backhaul beam from a same transmission configuration indicator, TCI, status pool for a control link between a base station and a mobile terminal of a relay, and

wherein the instruction is received by the repeater through a medium access control-control element MAC-CE.

20. An apparatus according to claim 17,

wherein the instructions further instruct the at least one processor to perform the method of the repeater by applying a default beam in the absence of a backhaul beam indication from a base station.