WO2018228701A1

WO2018228701A1 - Beam management in multi beam scenarios

Info

Publication number: WO2018228701A1
Application number: PCT/EP2017/064785
Authority: WO
Inventors: Juho Mikko Oskari Pirskanen; Timo Koskela; Samuli Heikki TURTINEN; Sami-Jukka Hakola
Original assignee: Nokia Technologies Oy
Priority date: 2017-06-16
Filing date: 2017-06-16
Publication date: 2018-12-20

Abstract

There are provided measures for beam management in multi beam scenarios. Such measures exemplarily comprise transmitting an initiation message initiating an access procedure for access to said communication network utilizing a first communication beam of said at least two communication beams, receiving an initiation response message indicative of beam management configuration, detecting a beam change to a second communication beam of said at least two communication beams, and signaling information indicative of said beam change utilizing said beam management configuration.

Description

Title

BEAM MANAGEMENT IN MULTI BEAM SCENARIOS Held

The present invention relates to beam management in multi beam scenarios. More specifically, the present invention exemplarily relates to measures (including methods, apparatuses and computer program products) for realizing beam management in multi beam scenarios.

Background

The present specification generally relates to expected issues of the future 3^rd Generation Partnership Project (3GPP) 5G radio access technology and as such is also applicable to other technologies like Long Term Evolution (LTE) and Long Term Evolution Advanced (LTE-A) systems.

In 5G, beamforming is assumed to be the key enabler for communication in higher frequency bands and one of the expected key challenges is the effort for determining and utilizing the best possible communication beam or set of candidate beams. The transceiver architecture proposed for 5G (hybrid transceiver architecture) with analogue beamforming imposes further challenges due to a limited number of concurrent directions/beams that can be formed and used for communication, which depends on the number of antenna ports.

In such multi beam scenario, to enable system access for a terminal, periodical transmission of system information by the network side may be required per direction where multiple beams cover specific area of the cell. Also corresponding directions need to be covered to provide resources for system access.

When a 5G NodeB (i.e., next generation NodeB, gNB) which is an access node intended for 5G scenarios (but may also be deployed on other scenarios like e.g. 4G scenarios or a 5G pre phase scenario) covers a specific area with a set of beams, synchronization signals (SS) are distributed by so-called SS bursts. Namely, always-on downlink (DL) signals are arranged in a periodically transmitted structure called SS burst set. An SS burst set consists of a finite number of SS bursts. An SS burst consists of a number of SS blocks. An SS block includes the primary signals necessary for an idle UE, such as new radio (primary/secondary) synchronization signal (NR-(P/S)SS) and physical broadcast channel (PBCH).

Figure 7 is a schematic diagram illustrating a multiple SS burst transmission. In particular, Figure 7 illustrates the concept of SS burst. As an example according to Figure 7, for SS burst 1 the analog beams 1 and 2 are active and transmitting respective SS blocks, and for SS burst 2 the beams 3 and 4 are active and transmitting respective SS blocks.

Figure 8 is a schematic diagram illustrating an SS block. In particular, from Figure 8, the SS-burst in a downlink subframe (each block may take one or more symbols) is derivable, having a corresponding uplink subframe.

A transmission of these SS blocks are assumed to be periodical so that e.g. initial access resources may be mapped to uplink (UL) sweep blocks.

In such scenario, due to the mobility change in environment (e.g. a blocking obstacle like lorry which may block the line-of-sight (LOS) signal), a UE may see better communication beams (than a currently utilized communication beam), or the current beam may become unsuitable for communication, so that the selected beam or a set of candidate beams may vary over time. This issue becomes particularly relevant during radio resource control (RRC) connection setup, RRC inactive to RRC connected state transition, user equipment (UE) based cell re-selection, or handover, and any other case in connection setup or re-establishment.

Namely, beam management is expected to use scheduling request - type of signaling (scheduling request, SR) which are resources for UE to send synchronized uplink transmission to indicate the change of the beam. A typical assumption is that these resources are configured to the UE by RRC signaling as depicted in Figure 9. Figure 9 shows a schematic diagram of an example of a system environment with signaling variants and in particular illustrates a configuration of SR resources for beam management. Due to long distances between a distributed unit (DU) and a centralized unit (CU), due to interface delays between CUs in case that context fetch is needed, and due CU processing delays, the CU response to a connection request message will not be immediate; rather, significant delays can be expected.

However, this introduces difficulties in relation to how beam management can be performed before first RRC signaling procedure is successfully performed.

If a UE would be able to perform beam management action only after successful RRC reconfiguration, the change of communication beam would lead to a connection failure, which would result in the UE re-trying the connection after some timer expiring which is used to indicate that connection setup is not successful, i.e. UE is not receiving expected response message from the network (NW). In a varying environment as described above in which the UE experiences permanent changes in availability or suitability of communication beams, this can lead to a situation where the UE needs to perform a series of re-tries illustrated in Figure 10. Figure 10 shows a schematic diagram of an example of a system environment with signaling variants and in particular illustrates a random access failure due to a beam change.

Such series of re-tries to be performed would increase the network load and introduce significant reduction in communication quality seen by the end user. Thus, basic design criterion of the system needs to be that connection setup success rate is very high. Aspects of the present invention address this identified basic design criterion to thereby improve this issue in beamformed systems.

The following known concepts or techniques may be considered in this regard.

Namely, according to present proposals, beam management can be initiated in the RRC connection setup or contention resolution message sent by the DU gNB to the UE during a random access procedure (utilizing a random access channel (RACH)) as shown in Figure 9. The RACH procedure is the first procedure through which a UE sends its first UL message to the network element serving as an access node (here gNB). The RACH procedure consists of at least four messages (MSG1 to MSG4). With MSG1 of the RACH procedure, the UE sends a random access message to the access node (RACH preamble). With MSG2 of the RACH procedure, the access node sends a random access response to the UE (random access response (RAR)). With MSG3 of the RACH procedure, the UE sends a UE identification message to the access node (RRC connection setup request/resume request). Finally, with MSG4 of the RACH procedure, the access node sends a contention resolution message to the UE.

While beam management can be initiated in the RRC connection setup or contention resolution message sent by the DU gNB to the UE during a RACH procedure, as can be derived from Figure 10, this concept would not enable the UE to initiate a communication link in case of a lost beam before receipt of all t e mentioned messages successfully via the beam selected for sending the random access preamble.

Present medium access control (MAC) protocol specifications do not provide any support for beam based operation.

However, current specification supports CSI-feedback transmission during active communication, but due to the beam based access and beam management (NW may maintain multiple candidate beams for peer) according to the scenario underlying the present invention, a CSI-feedback per beam would increase signaling overhead when the beams are not in active use but are considered to be e.g. in a candidate set of beams that may be used to communicate with UE. Further considerations were made such that in 5G a so-called "beam mobility" inside one cell or set of adjacent/overlapping cells would not be visible to e.g. RRC level. Accordingly, managing the beams and mobility between those cells would be effected via the L2 interface, most preferably in MAC layer.

According to a further concept, measurement reporting and beam refinement may be provided during a random access procedure (utilizing a random access channel (RACH)). Here, it is considered that if a UE would receive a channel state information reference signal/symbols (CSI-RS) configuration in a random access response (RAR) message to allow refining (sounding the channel), the existing beam might be beamformed better so that beamforming gain might be increased. However, this concept does not consider a situation in which the UE needs to change from one beam to another.

Hence, the problem arises that during RRC connection setup, RRC inactive to RRC connected state transition, UE based cell re-selection, or handover and any other case in connection setup or re-establishment, change in communication beam availability for a UE may lead to significant delay in the connection setup or re-establishment.

Hence, there is a need to provide for beam management in multi beam scenarios.

Summary

Various exemplary embodiments of the present invention aim at addressing at least part of the above issues and/or problems and drawbacks.

Various aspects of exemplary embodiments of the present invention are set out in the appended claims. According to an exemplary aspect of the present invention, there is provided a method for initiating a communication link in a cellular communication network in which a cell is covered by at least two communication beams, the method comprising transmitting an initiation message initiating an access procedure for access to said communication network utilizing a first communication beam of said at least two communication beams, receiving an initiation response message indicative of beam management configuration, detecting a beam change to a second communication beam of said at least two communication beams, and signaling information indicative of said beam change utilizing said beam management configuration.

According to an exemplary aspect of the present invention, there is provided a method for initiating a communication link in a cellular communication network in which a cell is covered by at least two communication beams, the method comprising receiving an initiation message initiating an access procedure for access of a communication endpoint in said cell to said communication network utilizing a first communication beam of said at least two communication beams, deciding beam management configuration for said communication endpoint, transmitting an initiation response message indicative of said beam management configuration, and receiving, utilizing said beam management configuration, information indicative of a beam change of said communication endpoint to a second communication beam of said at least two communication beams.

According to an exemplary aspect of t e present invention, there is provided an apparatus for initiating a communication link in a cellular communication network in which a cell is covered by at least two communication beams, the apparatus comprising at least one processor, at least one memory including computer program code, and at least one interface configured for communication with at least another apparatus, the at least one processor, with the at least one memory and the computer program code, being configured to cause the apparatus to perform transmitting an initiation message initiating an access procedure for access to said communication network utilizing a first communication beam of said at least two communication beams, receiving an initiation response message indicative of beam management configuration, detecting a beam change to a second communication beam of said at least two communication beams, and signaling information indicative of said beam change utilizing said beam management configuration.

According to an exemplary aspect of the present invention, there is provided an apparatus for initiating a communication link in a cellular communication network in which a cell is covered by at least two communication beams, the apparatus comprising at least one processor, at least one memory including computer program code, and at least one interface configured for communication with at least another apparatus, the at least one processor, with the at least one memory and the computer program code, being configured to cause the apparatus to perform receiving an initiation message initiating an access procedure for access of a communication endpoint in said cell to said communication network utilizing a first communication beam of said at least two communication beams, deciding beam management configuration for said communication endpoint, transmitting an initiation response message indicative of said beam management configuration, and receiving, utilizing said beam management configuration, information indicative of a beam change of said communication endpoint to a second communication beam of said at least two communication beams.

According to an exemplary aspect of t e present invention, there is provided an apparatus for initiating a communication link in a cellular communication network in which a cell is covered by at least two communication beams, the apparatus comprising transmitting circuitry configured to transmit an initiation message initiating an access procedure for access to said communication network utilizing a first communication beam of said at least two communication beams, receiving circuitry configured to receive an initiation response message indicative of beam management configuration, detecting circuitry configured to detect a beam change to a second communication beam of said at least two communication beams, and signaling circuitry configured to signal information indicative of said beam change utilizing said beam management configuration.

According to an exemplary aspect of the present invention, there is provided an apparatus for initiating a communication link in a cellular communication network in which a cell is covered by at least two communication beams, the apparatus comprising receiving circuitry configured to receive an initiation message initiating an access procedure for access of a communication endpoint in said cell to said communication network utilizing a first communication beam of said at least two communication beams, deciding circuitry configured to decide beam management configuration for said communication endpoint, and transmitting circuitry configured to transmit an initiation response message indicative of said beam management configuration, wherein said receiving circuitry is further configured to receive, utilizing said beam management configuration, information indicative of a beam change of said communication endpoint to a second communication beam of said at least two communication beams.

According to an exemplary aspect of the present invention, there is provided a computer program product comprising computer-executable computer program code which, when the program is run on a computer (e.g. a computer of an apparatus according to any one of the aforementioned apparatus-related exemplary aspects of the present invention), is configured to cause the computer to carry out the method according to any one of the aforementioned method-related exemplary aspects of the present invention. Such computer program product may comprise (or be embodied) a (tangible) computer-readable (storage) medium or the like on which the computer-executable computer program code is stored, and/or the program may be directly loadable into an internal memory of the computer or a processor thereof.

Any one of the above aspects enables an efficient communication beam management and maintenance/recovery to thereby solve at least part of the problems and drawbacks identified in relation to the prior art. By way of exemplary embodiments of the present invention, there is provided beam management in multi beam scenarios. More specifically, by way of exemplary embodiments of the present invention, there are provided measures and mechanisms for realizing beam management in multi beam scenarios.

Thus, improvement is achieved by methods, apparatuses and computer program products enabling/realizing beam management in multi beam scenarios. Brief description of t e drawings

In the following, the present invention will be described in greater detail by way of non-limiting examples with reference to the accompanying drawings, in which

Figure 1 is a block diagram illustrating an apparatus according to exemplary embodiments of the present invention, Figure 2 is a block diagram illustrating an apparatus according to exemplary embodiments of the present invention,

Figure 3 is a block diagram illustrating an apparatus according to exemplary embodiments of the present invention,

Figure 4 is a block diagram illustrating an apparatus according to exemplary embodiments of the present invention,

Figure 5 is a schematic diagram of a procedure according to exemplary embodiments of the present invention,

Figure 6 is a schematic diagram of a procedure according to exemplary embodiments of the present invention, Figure 7 is a schematic diagram illustrating an example of a multiple SS burst transmission,

Figure 8 is a schematic diagram illustrating an example of an SS block, Figure 9 shows a schematic diagram of an example of a system environment with signaling variants and in particular illustrates a configuration of SR resources for beam management, Figure 10 shows a schematic diagram of an example of a system environment with signaling variants and in particular illustrates a random access failure due to a beam change, Figure 11 shows a schematic diagram of an example of a system environment with signaling variants according to exemplary embodiments of the present invention and in particular illustrates a beam management action during a random access procedure, Figure 12 shows a schematic diagram of an example of a random access response message according to exemplary embodiments of the present invention,

Figure 13 shows a schematic diagram of an example of a random access response message according to exemplary embodiments of the present invention,

Figure 14 is a block diagram alternatively illustrating apparatuses according to exemplary embodiments of the present invention.

Detailed description of drawings and embodiments of the present invention

The present invention is described herein with reference to particular non- limiting examples and to what are presently considered to be conceivable embodiments of the present invention. A person skilled in the art will appreciate that the invention is by no means limited to these examples, and may be more broadly applied.

It is to be noted that the following description of the present invention and its embodiments mainly refers to specifications being used as non-limiting examples for certain exemplary network configurations and deployments. Namely, the present invention and its embodiments are mainly described in relation to 3GPP specifications being used as non-limiting examples for certain exemplary network configurations and deployments. As such, the description of exemplary embodiments given herein specifically refers to terminology which is directly related thereto. Such terminology is only used in the context of the presented non-limiting examples, and does naturally not limit the invention in any way. Rather, any other communication or communication related system deployment, etc. may also be utilized as long as compliant with the features described herein.

Hereinafter, various embodiments and implementations of the present invention and its aspects or embodiments are described using several variants and/or alternatives. It is generally noted that, according to certain needs and constraints, all of the described variants and/or alternatives may be provided alone or in any conceivable combination (also including combinations of individual features of the various variants and/or alternatives).

According to exemplary embodiments of the present invention, in general terms, there are provided measures and mechanisms for (enabling/realizing) beam management in multi beam scenarios.

In particular, according to exemplary embodiments of the present invention, a technique for initiating a communication link between a UE and a serving access point (AP) or a group of APs during initiation of the communication or handover, cell reselection or becoming active after discontinuous reception (DRX) in a beamformed system (with possible radio multi- connectivity) is provided.

Figure 11 shows a schematic diagram of an example of a system environment with signaling variants according to exemplary embodiments of the present invention and in particular illustrates a beam management action during a random access procedure. According to the random access procedure, the UE determines that RACH is needed.

Once determined, the UE transmits a RACH preamble towards a DU gNB. The DU gNB may respond by means of a random access response message which is in any way indicative of SR resources.

According to exemplary embodiments of the present invention, upon receipt of such random access response message, the UE initiates a beam evaluation process. After processing the random access response, the UE transmits an RRC message including a connection setup request or UL data towards the DU gNB and continues the beam evaluation process.

The DU gNB responds by means of a hybrid automatic repeat request (HARQ) feedback/re-transmission (potentially on PDCCH).

In addition, the DU gNB sends an RRC message including the connection setup request or the UL data towards the CU gNB that responds utilizing an RRC connection setup or contention resolution message. If necessary, the CU gNB effects a context fetch beforehand.

Subsequently, the DU gNB transmits PDCCH TX to schedule DL to the UE.

Furthermore, the DU gNB transmits an RRC connection setup or contention resolution message towards the UE.

If, during this random access procedure, as depicted in Figure 11, a beam change is detected by the UE, the UE transmits an SR (based on the indicated SR resources) for indicating the beam change towards the DU gNB.

Thus, for the subsequent processing, the DU gNB is in a position to consider the indicated beam change of the UE. In general terms, t e approach according to exemplary embodiments of the present invention exemplarily comprises sending a random access preamble by the UE to the network and receiving random access response (RAR) message with beam management signaling resources and potentially other beam configuration parameters. A beam management signaling resource can be e.g. an SR (scheduling request) or other dedicated UL signal which can be transmitted when UE is uplink synchronized or it may be a dedicated physical random access channel (PRACH) preamble resource. The signal may be configured to be transmitted on so called PRACH periods that map a specific set of RACH preambles (or SR resources) to specific SS blocks or specific CSI-RS resources. A specific CSI-RS resource may correspond to a specific beam. This approach may further comprise utilizing the received resources and configuration parameters for beam management actions to indicate communication beam change based on the received parameters. This approach may still further comprise (potentially) utilizing a received cell radio network temporary identifier (C-RNTI) to determine beam management signaling resources (such as SR) so that the RAR message size to be transmitted can be optimized. According to this approach, the received SR resources may be valid for all SS block beams or may be valid for a partial set of SS block beams or an individual sub beam of an SS block (identified by beam specific CSI-RS). Alternatively, the beam management signaling resource may correspond to a specific beam (CSI-RS beam). In one option, the UE is given a set of signaling resources where each resource corresponds to a specific beam (CSI-RS resource) in similar manner as signaling resource would correspond to specific SS block, but UE would be able to indicate beams with finer granularity.

Figure 1 is a block diagram illustrating an apparatus according to exemplary embodiments of the present invention. The apparatus may be a terminal 10 such as a user equipment (UE) comprising a transmitting circuitry 11, a receiving circuitry 12, a detecting circuitry 13, and a signaling circuitry 14. The transmitting circuitry 11 transmits an initiation message initiating an access procedure for access to said communication network utilizing a first communication beam of said at least two communication beams. The receiving circuitry 12 receives an initiation response message indicative of beam management configuration. The detecting circuitry 13 detects a beam change to a second communication beam of said at least two communication beams. The signaling circuitry 14 signals information indicative of said beam change utilizing said beam management configuration. Figure 5 is a schematic diagram of a procedure according to exemplary embodiments of the present invention. The apparatus according to Figure 1 may perform the method of Figure 5 but is not limited to this method. The method of Figure 5 may be performed by the apparatus of Figure 1 but is not limited to being performed by this apparatus.

As shown in Figure 5, a procedure according to exemplary embodiments of the present invention comprises an operation of transmitting (S51) an initiation message initiating an access procedure for access to said communication network utilizing a first communication beam of said at least two communication beams, an operation of receiving (S52) an initiation response message indicative of beam management configuration, an operation of detecting (S53) a beam change to a second communication beam of said at least two communication beams, and an operation of signaling (S54) information indicative of said beam change utilizing said beam management configuration. Figure 2 is a block diagram illustrating an apparatus according to exemplary embodiments of the present invention. In particular, Figure 2 illustrates a variation of the apparatus shown in Figure 1. The apparatus according to Figure 2 may thus further comprise deriving circuitry 21 , evaluating circuitry 22, deciding circuitry 23, and/or continuing circuitry 24.

In an embodiment at least some of the functionalities of the apparatus shown in Figure 1 (or 2) may be shared between two physically separate devices forming one operational entity. Therefore, the apparatus may be seen to depict the operational entity comprising one or more physically separate devices for executing at least some of the described processes.

According to a variation of the procedure shown in Figure 5, exemplary additional operations are given, which are inherently independent from each other as such. Namely, according to such variation, an exemplary method according to exemplary embodiments of the present invention may comprise an operation of continuing further communication link signaling in relation to said initiating said communication link after said beam change.

According to a variation of the procedure shown in Figure 5, said initiation response message is further indicative of at least one beam configuration parameter, and said signaling (S54) is based on said at least one beam configuration parameter.

According to a further variation of the procedure shown in Figure 5, said initiation response message is indicative of a beam management configuration index. According to such variation, exemplary additional operations are given, which are inherently independent from each other as such. Namely, according to such variation, an exemplary method according to exemplary embodiments of the present invention may comprise an operation of receiving a system information block including a plurality of configurations respectively associated with beam management configuration indices, and an operation of deriving said beam management configuration from said plurality of configurations based on said beam management configuration index.

According to a further variation of the procedure shown in Figure 5, said initiation response message includes a cell radio network temporary identifier. According to such variation, exemplary additional operations are given, which are inherently independent from each other as such. Namely, according to such variation, an exemplary method according to exemplary embodiments of the present invention may comprise an operation of deriving said beam management configuration index from said cell radio network temporary identifier.

According to a further variation of the procedure shown in Figure 5, exemplary additional operations are given, which are inherently independent from each other as such. Namely, according to such variation, an exemplary method according to exemplary embodiments of the present invention may comprise an operation of receiving a connection setup message indicative of changed or maintained beam management configuration.

According to a further variation of the procedure shown in Figure 5, exemplary additional operations are given, which are inherently independent from each other as such. Namely, according to such variation, an exemplary method according to exemplary embodiments of the present invention may comprise an operation of receiving beam evaluation criteria information, an operation of evaluating suitability of said at least two communication beams, and an operation of deciding, on the basis of said evaluating, whether to change to said second communication beam.

The initiation message may be a random access preamble (RACH preamble).

The initiation response message may be a random access response (RAR). The beam management configuration may comprise beam management communication resources and may further comprise other communication related parameters.

In particular, the beam management configuration may be/comprise scheduling request (SR) resources.

Figure 3 is a block diagram illustrating an apparatus according to exemplary embodiments of the present invention. The apparatus may be an access node 30 such as a NodeB (gNB) comprising a receiving circuitry 31, a deciding circuitry 32, and a transmitting circuitry 33. The receiving circuitry 31 receives an initiation message initiating an access procedure for access of a communication endpoint in said cell to said communication network utilizing a first communication beam of said at least two communication beams. The deciding circuitry 32 decides beam management configuration for said communication endpoint. The transmitting circuitry 33 transmits an initiation response message indicative of said beam management configuration. The receiving circuitry 31 further receives, utilizing said beam management configuration, information indicative of a beam change of said communication endpoint to a second communication beam of said at least two communication beams. Figure 6 is a schematic diagram of a procedure according to exemplary embodiments of the present invention. The apparatus according to Figure 3 may perform the method of Figure 6 but is not limited to this method. The method of Figure 6 may be performed by the apparatus of Figure 3 but is not limited to being performed by this apparatus.

As shown in Figure 6, a procedure according to exemplary embodiments of the present invention comprises an operation of receiving (S61) an initiation message initiating an access procedure for access of a communication endpoint in said cell to said communication network utilizing a first communication beam of said at least two communication beams, an operation of deciding (S62) beam management configuration for said communication endpoint, an operation of transmitting (S63) an initiation response message indicative of said beam management configuration, and an operation of receiving (S64), utilizing said beam management configuration, information indicative of a beam change of said communication endpoint to a second communication beam of said at least two communication beams.

Figure 4 is a block diagram illustrating an apparatus according to exemplary embodiments of the present invention. In particular, Figure 4 illustrates a variation of t e apparatus shown in Figure 3. The apparatus according to Figure 4 may thus further comprise providing circuitry 41, and/or deriving circuitry 42. In an embodiment at least some of the functionalities of the apparatus shown in Figure 3 (or 4) may be shared between two physically separate devices forming one operational entity. Therefore, the apparatus may be seen to depict the operational entity comprising one or more physically separate devices for executing at least some of the described processes.

According to a variation of the procedure shown in Figure 6, said initiation response message is further indicative of at least one beam configuration parameter. According to a further variation of the procedure shown in Figure 6, exemplary additional operations are given, which are inherently independent from each other as such. Namely, according to such variation, an exemplary method according to exemplary embodiments of the present invention may comprise an operation of providing a system information block including a plurality of configurations respectively associated with beam management configuration indices. According to such variation, the initiation response message is indicative of a beam management configuration index of said beam management configuration indices corresponding to said beam management configuration decided for said communication endpoint.

According to a further variation of the procedure shown in Figure 6, exemplary additional operations are given, which are inherently independent from each other as such. Namely, according to such variation, an exemplary method according to exemplary embodiments of the present invention may comprise an operation of deriving a cell radio network temporary identifier based on said beam management configuration index. According to such variation, the initiation response message includes said cell radio network temporary identifier.

According to a further variation of the procedure shown in Figure 6, exemplary additional operations are given, which are inherently independent from each other as such. Namely, according to such variation, an exemplary method according to exemplary embodiments of the present invention may comprise an operation of transmitting a connection setup message indicative of changed or maintained beam management configuration.

According to a further variation of the procedure shown in Figure 6, exemplary additional operations are given, which are inherently independent from each other as such. Namely, according to such variation, an exemplary method according to exemplary embodiments of the present invention may comprise an operation of transmitting beam evaluation criteria information.

In more specific terms, according to exemplary embodiments of the present invention, for the best beam evaluation (evaluation which beam is best), the UE may follow beam evaluation criteria provided by the gNB in system information (e.g. system information block (SIB)) or by dedicated signalling in a previous connection. Alternatively, the UE may be given a CSI-RS configuration in the RAR (MSG2 of RACH procedure) that corresponds to a current SS block, or it may be a common configuration that is used for all or a set of SS blocks in a cell. By obtaining the CSI-RS configuration, the UE is able to detect potential beams in more refined level. An SS block beam can be a composite beam of multiple sub beams which can be identified using beam specific CSI-RS. Alternatively, the UE may be provided with CSI-RS configuration corresponding to an SS block where the CSI-RS beam corresponds to an SS block beam; thus it would then base the beam management actions on the measurements on the SS block or CSI-RS. In yet one more alternative, if no CSI-RS configuration is given to the UE, it performs beam management based on SS block measurements. The UE derives an SS block reference signal received power (RSRP) based on the measurements on the new radio secondary synchronization signal (NR- SSS), the new radio primary synchronization signal (NR-PSS), and/or the PBCH demodulation reference signal (DMRS). These signals may be used in any combination to derive RSRP, e.g. NR-SSS together with PBCH DMRS. Alternatively or additionally, UE may use other measurement quantities such as reference signal received quality (RSRQ)/signal to interference (and noise) ratio (SINR).

The initiation of beam management may be performed by high level implementation.

As mentioned above, according to exemplary embodiments of the present invention, the access node (e.g. gNB) provides the SR resources used for beam management to the terminal.

This may be effected by (explicitly) signaling the SR resources. In so doing, the following parameters may be included in the RAR message as shown in Figure 12, illustrating a schematic diagram of an example of a random access response message according to exemplary embodiments of the present invention: "Prach Root", with possible values from 1 to 70, thereby resulting in 7 bits; "srCyclicShiftV" ("srCyclicShift") with possible values from 0 to 11 , thereby resulting in 4 bits;

"rachBandl ndex" ("RACH band") with possible values from 0 to 7, thereby resulting in 3 bits.

As an alternative, this may be effected by signaling an SR resource index and SR resources in a system information block (SIB), and in that the RAR only indicates the SR resource index as shown in Figure 13, illustrating a schematic diagram of an example of a random access response message according to exemplary embodiments of the present invention. According to such alternative, the RAR message size would be limited. Alternatively (not shown), the UE may determinate the SR resources index based on the temporary C-RNTI which is given in the RAR message by using SR resources (i.e., number of SR resources) broadcasted in SIB. The determination of the index may be done for example following manner: SR_resource_l ndex = Modulo(C-RNTI , number_SR_resources)

According to such alternative, the RAR message size would not be increased, since the C-RNTI (normally included in the RAR message) would indicate the SR resource.

According to further exemplary embodiments of the present invention, contention resolution is addressed.

Namely, generally, the RACH message sent by an UE is contentious and multiple UE may have transmitted the same RACH signature simultaneously and may thus consider a RAR message subsequently sent by the DU gNB as being transmitted to them.

Hence, according to the further exemplary embodiments, with the RRC connection setup or contention resolution message sent by the DU gNB to the UE (see Figure 11), the network may re-allocate the SR resources or may indicate that the UE may continue to use the SR configuration received in the RAR message. Here, the following two cases have to be considered:

Case a) Two or more UEs stay in the same beam, i.e., no UE changes the beam: In this case, the processing according to the exemplary embodiments of the present invention does not differ from what would happen without application of the invention. Namely, collision would continue up to the transmission of MSG3 of RACH procedure (RRC connection setup request/resume request) from the respective UE to the DU gNB, as both UEs would use a grant received in the RAR message (i.e., would consider the grant as being transmitted to them).

Case b) An UE moves to another beam after receiving the RAR, while the other UE remains in the original beam: For this case, the exemplary embodiments of the present invention provide additional contention resolution, as the UE receiving the RAR and staying in the beam would use a received grant in RAR for transmitting MSG3 of RACH procedure (RRC connection setup request/resume request) from the UE to the DU gNB. The other UE that has moved to the other beam would perform an SR transmission based on a received SR resource to indicate the beam change. The network would then send a new DL grant in physical downlink control channel (PDCCH) for transmitting MSG3 of RACH procedure (RRC connection setup request/resume request) from the UE to the DU gNB that would not anymore collide with the other UE.

Accordingly, according to exemplary embodiments of the present invention, RACH performance upon beam changes during connection setup is improved. The above-described procedures and functions may be implemented by respective functional elements, processors, or the like, as described below.

In the foregoing exemplary description of the network entity, only the units that are relevant for understanding the principles of the invention have been described using functional blocks. The network entity may comprise further units that are necessary for its respective operation. However, a description of these units is omitted in this specification. The arrangement of the functional blocks of the devices is not construed to limit the invention, and the functions may be performed by one block or further split into sub-blocks.

When in the foregoing description it is stated that the apparatus, i.e. network entity (or some other means) is configured to perform some function, this is to be construed to be equivalent to a description stating that a (i.e. at least one) processor or corresponding circuitry, potentially in cooperation with computer program code stored in the memory of the respective apparatus, is configured to cause the apparatus to perform at least the thus mentioned function. Also, such function is to be construed to be equivalently implementable by specifically configured circuitry or means for performing the respective function (i.e. the expression "unit configured to" is construed to be equivalent to an expression such as "means for"). In Figure 14, an alternative illustration of apparatuses according to exemplary embodiments of the present invention is depicted. As indicated in Figure 14, according to exemplary embodiments of the present invention, the apparatus (terminal) 10' (corresponding to the terminal 10) comprises a processor 141, a memory 142 and an interface 143, which are connected by a bus 144 or the like. Further, according to exemplary embodiments of the present invention, the apparatus (access node) 30' (corresponding to the access node 30) comprises a processor 145, a memory 146 and an interface 147, which are connected by a bus 148 or the like, and the apparatuses may be connected via link 149, respectively.

The processor 141/145 and/or the interface 143/147 may also include a modem or the like to facilitate communication over a (hardwire or wireless) link, respectively. The interface 143/147 may include a suitable transceiver coupled to one or more antennas or communication means for (hardwire or wireless) communications with the linked or connected device(s), respectively. The interface 143/147 is generally configured to communicate with at least one other apparatus, i.e. the interface thereof. The memory 142/146 may store respective programs assumed to include program instructions or computer program code that, when executed by the respective processor, enables the respective electronic device or apparatus to operate in accordance with the exemplary embodiments of the present invention.

In general terms, the respective devices/ apparatuses (and/or parts thereof) may represent means for performing respective operations and/or exhibiting respective functionalities, and/or the respective devices (and/or parts thereof) may have functions for performing respective operations and/or exhibiting respective functionalities.

When in the subsequent description it is stated that the processor (or some other means) is configured to perform some function, this is to be construed to be equivalent to a description stating that at least one processor, potentially in cooperation with computer program code stored in the memory of the respective apparatus, is configured to cause the apparatus to perform at least the thus mentioned function. Also, such function is to be construed to be equivalently implementable by specifically configured means for performing the respective function (i.e. the expression "processor configured to [cause the apparatus to] perform xxx-ing" is construed to be equivalent to an expression such as "means for xxx-ing").

According to exemplary embodiments of the present invention, an apparatus representing the terminal 10 (for initiating a communication link in a cellular communication network in which a cell is covered by at least two communication beams) comprises at least one processor 141, at least one memory 142 including computer program code, and at least one interface 143 configured for communication with at least another apparatus. The processor (i.e. the at least one processor 141, with the at least one memory 142 and the computer program code) is configured to perform transmitting an initiation message initiating an access procedure for access to said communication network utilizing a first communication beam of said at least two communication beams (thus the apparatus comprising corresponding means for transmitting), to perform receiving an initiation response message indicative of beam management configuration (thus the apparatus comprising corresponding means for receiving), to perform detecting a beam change to a second communication beam of said at least two communication beams (thus the apparatus comprising corresponding means for detecting), and to perform signaling information indicative of said beam change utilizing said beam management configuration (thus the apparatus comprising corresponding means for signaling).

According to further exemplary embodiments of the present invention, an apparatus representing the access node 30 (for initiating a communication link in a cellular communication network in which a cell is covered by at least two communication beams) comprises at least one processor 145, at least one memory 146 including computer program code, and at least one interface 147 configured for communication with at least another apparatus. The processor (i.e. the at least one processor 145, with the at least one memory 146 and the computer program code) is configured to perform receiving an initiation message initiating an access procedure for access of a communication endpoint in said cell to said communication network utilizing a first communication beam of said at least two communication beams (thus the apparatus comprising corresponding means for receiving), to perform deciding beam management configuration for said communication endpoint (thus the apparatus comprising corresponding means for deciding), to perform transmitting an initiation response message indicative of said beam management configuration (thus the apparatus comprising corresponding means for transmitting), and to perform receiving, utilizing said beam management configuration, information indicative of a beam change of said communication endpoint to a second communication beam of said at least two communication beams (thus the apparatus comprising corresponding means for receiving). For further details regarding the operability/f unctionality of the individual apparatuses, reference is made to the above description in connection with any one of Figures 1 to 13, respectively. For the purpose of the present invention as described herein above, it should be noted that

- method steps likely to be implemented as software code portions and being run using a processor at a network server or network entity (as examples of devices, apparatuses and/or modules thereof, or as examples of entities including apparatuses and/or modules therefore), are software code independent and can be specified using any known or future developed programming language as long as the functionality defined by the method steps is preserved;

- generally, any method step is suitable to be implemented as software or by hardware without changing the idea of the embodiments and its modification in terms of the functionality implemented;

- method steps and/or devices, units or means likely to be implemented as hardware components at the above-defined apparatuses, or any module(s) thereof, (e.g., devices carrying out the functions of the apparatuses according to the embodiments as described above) are hardware independent and can be implemented using any known or future developed hardware technology or any hybrids of these, such as MOS (Metal Oxide Semiconductor), CMOS (Complementary MOS), BiMOS (Bipolar MOS), BiCMOS (Bipolar CMOS), ECL (Emitter Coupled Logic), TTL (Transistor- Transistor Logic), etc., using for example ASIC (Application Specific IC (Integrated Circuit)) components, FPGA (Field-programmable Gate Arrays) components, CPLD (Complex Programmable Logic Device) components or DSP (Digital Signal Processor) components;

- devices, units or means (e.g. the above-defined network entity or network register, or any one of their respective units/means) can be implemented as individual devices, units or means, but this does not exclude that they are implemented in a distributed fashion throughout the system, as long as the functionality of the device, unit or means is preserved; - an apparatus like t e user equipment and the network entity /network register may be represented by a semiconductor chip, a chipset, or a (hardware) module comprising such chip or chipset; this, however, does not exclude the possibility that a functionality of an apparatus or module, instead of being hardware implemented, be implemented as software in a (software) module such as a computer program or a computer program product comprising executable software code portions for execution/being run on a processor;

- a device may be regarded as an apparatus or as an assembly of more than one apparatus, whether functionally in cooperation with each other or functionally independently of each other but in a same device housing, for example.

In general, it is to be noted that respective functional blocks or elements according to above-described aspects can be implemented by any known means, either in hardware and/or software, respectively, if it is only adapted to perform the described functions of the respective parts. The mentioned method steps can be realized in individual functional blocks or by individual devices, or one or more of the method steps can be realized in a single functional block or by a single device.

Generally, any method step is suitable to be implemented as software or by hardware without changing the idea of the present invention. Devices and means can be implemented as individual devices, but this does not exclude that they are implemented in a distributed fashion throughout the system, as long as the functionality of the device is preserved. Such and similar principles are to be considered as known to a skilled person.

Software in the sense of the present description comprises software code as such comprising code means or portions or a computer program or a computer program product for performing the respective functions, as well as software (or a computer program or a computer program product) embodied on a tangible medium such as a computer-readable (storage) medium having stored thereon a respective data structure or code means/portions or embodied in a signal or in a chip, potentially during processing thereof. The present invention also covers any conceivable combination of method steps and operations described above, and any conceivable combination of nodes, apparatuses, modules or elements described above, as long as the above-described concepts of methodology and structural arrangement are applicable.

In view of the above, there are provided measures for beam management in multi beam scenarios. Such measures exemplarily comprise transmitting an initiation message initiating an access procedure for access to said communication network utilizing a first communication beam of said at least two communication beams, receiving an initiation response message indicative of beam management configuration, detecting a beam change to a second communication beam of said at least two communication beams, and signaling information indicative of said beam change utilizing said beam management configuration.

Even though the invention is described above with reference to the examples according to the accompanying drawings, it is to be understood that the invention is not restricted thereto. Rather, it is apparent to those skilled in the art that the present invention can be modified in many ways without departing from the scope of the inventive idea as disclosed herein. acronyms and abbreviations

3GPP 3rd Generation Partnership Project

AP access point

C-RNTI cell radio network temporary identifier

CSI-RS channel state information reference signal/symbols

CU centralized unit DL downlink

DMRS dem odulation reference signal

DRX discontinuous reception

DU distributed u nit

gNB next generation NodeB

HARQ hybrid autom atic repeat request

LOS line-of-sight

LTE Long Term Evolution

LTE-A Long Term Evolution Advanced

MAC m ediu m access control

NR- PSS new radio prim ary synchronization signal

NR- SSS new radio secondary synchronization signal

NW network

PBCH physical broadcast channel

PDCCH physical downlink control channel

PRACH physical random access channel

RACH random access chan nel

RAR random access response

RRC radio resource control

RSRP reference signal received power

SI B system inform ation block

SR scheduling request

SS synch ronization signal

UE user equipm ent

UL uplink

Claims

1. A method for initiating a communication link in a cellular communication network in which a cell is covered by at least two communication beams, the method comprising

transmitting an initiation message initiating an access procedure for access to said communication network utilizing a first communication beam of said at least two communication beams,

receiving an initiation response message indicative of beam management configuration,

detecting a beam change to a second communication beam of said at least two communication beams, and

signaling information indicative of said beam change utilizing said beam management configuration.

2. The method according to claim 1, further comprising

continuing further communication link signaling in relation to said initiating said communication link after said beam change.

3. The method according to claim 1 or 2, wherein

said initiation response message is further indicative of at least one beam configuration parameter, and

said signaling is based on said at least one beam configuration parameter.

4. The method according to any of claims 1 to 3, wherein

said initiation response message is indicative of a beam management configuration index, and said method further comprises

receiving a system information block including a plurality of configurations respectively associated with beam management configuration indices, and deriving said beam management configuration from said plurality of configurations based on said beam management configuration index.

5. The method according to claim 4, wherein

said initiation response message includes a cell radio network temporary identifier, and said method further comprises

deriving said beam management configuration index from said cell radio network temporary identifier.

6. The method according to any of claims 1 to 5, further comprising

receiving a connection setup message indicative of changed or maintained beam management configuration.

7. The method according to any of claims 1 to 6, further comprising

receiving beam evaluation criteria information,

evaluating suitability of said at least two communication beams, and deciding, on the basis of said evaluating, whether to change to said second communication beam.

8. The method according to any of claims 1 to 7, wherein

the method is operable at or by a terminal, user equipment, mobile station or modem, and/or

the method is operable in at least one of a LTE and a LTE-A cellular system, and/or

said initiation message is a random access preamble, and/or said initiation response message is a random access response, and/or said beam management configuration comprises scheduling request resources.

9. A method for initiating a communication link in a cellular communication network in which a cell is covered by at least two communication beams, the method comprising receiving an initiation message initiating an access procedure for access of a communication endpoint in said cell to said communication network utilizing a first communication beam of said at least two communication beams,

deciding beam management configuration for said communication endpoint,

transmitting an initiation response message indicative of said beam management configuration, and

receiving, utilizing said beam management configuration, information indicative of a beam change of said communication endpoint to a second communication beam of said at least two communication beams.

10. The method according to claim 9, wherein

said initiation response message is further indicative of at least one beam configuration parameter.

11. The method according to claim 9 or 10, further comprising

providing a system information block including a plurality of configurations respectively associated with beam management configuration indices, wherein

said initiation response message is indicative of a beam management configuration index of said beam management configuration indices corresponding to said beam management configuration decided for said communication endpoint.

12. The method according to claim 11, further comprising

deriving a cell radio network temporary identifier based on said beam management configuration index, wherein

said initiation response message includes said cell radio network temporary identifier.

13. The method according to any of claims 9 to 12, further comprising transmitting a connection setup message indicative of changed or maintained beam management configuration.

The method according to any of claims 9 to 13, further comprising transmitting beam evaluation criteria information.

15. The method according to any of claims 9 to 14, wherein

the method is operable at or by a base station or access node of the cellular communication network, and/or

16. An apparatus for initiating a communication link in a cellular communication network in which a cell is covered by at least two communication beams, the apparatus comprising

at least one processor,

at least one memory including computer program code, and at least one interface configured for communication with at least another apparatus,

the at least one processor, with the at least one memory and the computer program code, being configured to cause the apparatus to perform :

detecting a beam change to a second communication beam of said at least two communication beams, and signaling information indicative of said beam change utilizing said beam management configuration.

17. The apparatus according to claim 16, wherein

the at least one processor, with the at least one memory and the computer program code, is further configured to cause the apparatus to perform :

18. The apparatus according to claim 16 or 17, wherein

said signaling is based on said at least one beam configuration parameter.

19. The apparatus according to any of claims 16 to 18, wherein

said initiation response message is indicative of a beam management configuration index, and

receiving a system information block including a plurality of configurations respectively associated with beam management configuration indices, and

deriving said beam management configuration from said plurality of configurations based on said beam management configuration index.

20. The apparatus according to claim 19, wherein

said initiation response message includes a cell radio network temporary identifier, and the at least one processor, with the at least one memory and the computer program code, is further configured to cause the apparatus to perform :

21. The apparatus according to any of claims 16 to 20, wherein

the at least one processor, with the at least one memory and the computer program code, is further configured to cause the apparatus to perform:

22. The apparatus according to any of claims 16 to 21, wherein

receiving beam evaluation criteria information,

23. An apparatus for initiating a communication link in a cellular communication network in which a cell is covered by at least two communication beams, the apparatus comprising

at least one processor,

the at least one processor, with the at least one memory and the computer program code, being configured to cause the apparatus to perform : receiving an initiation message initiating an access procedure for access of a communication endpoint in said cell to said communication network utilizing a first communication beam of said at least two communication beams,

deciding beam management configuration for said communication endpoint,

24. The apparatus according to claim 23, wherein

25. The apparatus according to claim 23 or 24, wherein

26. The apparatus according to claim 25, wherein

the at least one processor, with the at least one memory and the computer program code, is further configured to cause the apparatus to perform : deriving a cell radio network temporary identifier based on said beam management configuration index, wherein

27. The apparatus according to any of claims 23 to 26, wherein

transmitting a connection setup message indicative of changed or maintained beam management configuration.

28. The apparatus according to any of claims 23 to 27, wherein

transmitting beam evaluation criteria information.

29. An apparatus for initiating a communication link in a cellular communication network in which a cell is covered by at least two communication beams, the apparatus comprising

transmitting circuitry configured to transmit an initiation message initiating an access procedure for access to said communication network utilizing a first communication beam of said at least two communication beams,

receiving circuitry configured to receive an initiation response message indicative of beam management configuration,

detecting circuitry configured to detect a beam change to a second communication beam of said at least two communication beams, and

signaling circuitry configured to signal information indicative of said beam change utilizing said beam management configuration.

30. An apparatus for initiating a communication link in a cellular communication network in which a cell is covered by at least two communication beams, the apparatus comprising

receiving circuitry configured to receive an initiation message initiating an access procedure for access of a communication endpoint in said cell to said communication network utilizing a first communication beam of said at least two communication beams,

deciding circuitry configured to decide beam management configuration for said communication endpoint, and

transmitting circuitry configured to transmit an initiation response message indicative of said beam management configuration, wherein

said receiving circuitry is further configured to receive, utilizing said beam management configuration, information indicative of a beam change of said communication endpoint to a second communication beam of said at least two communication beams.

31. A computer program product comprising computer-executable computer program code which, when the program is run on a computer, is configured to cause the computer to carry out the method according to any one of claims 1 to 8 or 9 to 15.

32. The computer program product according to claim 31, wherein the computer program product comprises a computer-readable medium on which the computer-executable computer program code is stored, and/or wherein the program is directly loadable into an internal memory of the computer or a processor thereof.