WO2019069504A1

WO2019069504A1 - System and methods for transmission and reception of paging signals in multi-beam operational system

Info

Publication number: WO2019069504A1
Application number: PCT/JP2018/022187
Authority: WO
Inventors: Phong Nguyen; Takahiro Sasaki
Original assignee: Nec Corporation
Priority date: 2017-10-02
Filing date: 2018-06-11
Publication date: 2019-04-11

Abstract

A method for use in a NR system comprising a plurality of gNBs and a plurality of NR-Ues, the NR-UEs configured to periodically wake up to monitor paging signals from the gNBs is provided. The method comprises: allocating, at a gNB (110) of the plurality of gNBs, a resource pool (212, 222, 270) which is associated with a NR paging frame for beam reporting from an intended NR-UEs or intended group of NR-UEs; monitoring, at the gNB (110), the configured resource pool (212, 222, 270) for one or more beam reports (451, 452, 453) from one or more NR-UEs; and transmitting, from the gNB (110) and according to the one or more beam reports (451, 452, 453), beam-formed paging signals which are directed to one or more in coverage NR-UEs.

Description

SYSTEM AND METHODS FOR TRANSMISSION AND RECEPTION OF PAGING SIGNALS IN MULTI-BEAM OPERATIONAL SYSTEM

　　The present invention relates to advanced wireless communication. In particular, although not exclusively, the invention relates to transmission and reception of paging signals in multi-beam systems.

<ABBREVIATIONS>

　　Fourth generation (4G) 3GPP telecommunications systems are being successfully deployed at accelerating pace all over the world. These systems enable more advanced services and applications that make use of the inherent benefit of LTE/LTE-A/LTE-A Pro technologies, such as higher data rate, lower latency, enhanced coverage, and sidelink communication.

　　Much attention has now been focused on the development of the next generation technology and services, also called fifth generation (5G) technology. Although the design and deployment of any wireless system or cellular system takes many years, development of the 5G technology systems is now being investigated progressively in 3GPP standardisation community, with the initial target for commercial deployment of 5G systems being commencing in 2020 and lately being brought forward to 2018. In this regard, work has started in ITU and 3GPP in developing requirements and performing feasibility studies for technological specifications development for new radio (NR) systems.

　　According to 3GPP TSG Radio Access Network Working Group 1 (RAN-WG1), the NR or 5G system shall be designed for deployment in frequency bands ranging from UHF (Ultra-high frequency), SHF (Super-high frequency) to EHF (Extremely-high frequency) particularly from below 3GHz to 52.6GHz frequency bands.

　　In order to reduce propagation loss of radio waves and increase transmission distance when transmitting and receiving radio signals in SHF and EHF bands, several technologies, including beam-forming techniques, have been endorsed or adopted for use in NR systems by 3GPP-RAN, where one or multiple user equipments (UEs) may be serviced with a designated narrow beam. In multi-beam operation, in order to cover a spatial area, beam-sweeping approach has also been considered at least for minimum system information broadcast and paging as part of initial access in NR system where multiple narrow beams carrying the same information or data are transmitted and/or received during a time interval.

　　In general wireless communication systems, such as LTE, efficient procedures have been designed for use and have been considered by 3GPP RAN as a baseline for NR systems in multi-beam operation. Fig. 1 illustrates a paging message structure 10, according to LTE's technology 11, and as adapted for 5G or NR technology 12.

　　According to LTE, the LTE paging structure 11, a paging cycle is defined to allow the UE to sleep most of the time with no receiver processing and to only briefly wake up at predetermined time intervals to monitor the L1/L2 control channels (e.g. PDCCHs) for the first paging signal i.e. a paging indicator (e.g. the first paging signal 11.1) intended for the group that it belongs to. The first paging signal 11.1 may comprise a group identity used for paging i.e. P-RNTI. If a UE detects a positive P-RNTI on a PDCCH while it wakes up, it will process a corresponding second paging signal 11.2 on the associated shared channel e.g. PDSCH.

　　The second paging signal may include the identity of the UE(s) being paged, and a UE who is not finding its identity in the second paging signal will discard the received signals and go back to sleep according to its configured DRX cycle.

　　Since the location of a UE typically is not known on a cell level in LTE system, the paging message is typically transmitted by all eNBs across multiple cells in the so-called 'tracking area' where 'tracking areas' are controlled and managed by the MME.

　　When LTE paging procedure 11 is applied to the multi-beam operation of an NR-system, as outlined in 12, the paging message will be transmitted on every

beam

13, 14, 15 covering a partial area (e.g. up to 64 beams according to the latest 3GPP-RAN-WG1's agreement) and across multiple TRPs of multiple cells by all gNBs in a 'tracking area' using beam sweeping 16.

　　While waking up, a NR-UE has to monitor the NR L1/L2 control channels (i.e.NR-PDCCHs) on each configured beam for the first paging signal 11.1 intended for the group that it belong. If the UE detects a positive NR-P-RNTI on a NR-PDCCH, it will process the corresponding second paging signal 12.2 on the associated shared channel i.e. NR-PDSCH. The second paging signal may include the identity of the UE(s) being paged, and a UE who is not identified in the second paging signal will discard the received signals and go back to sleep according to its configured DRX cycle.

　　At the network side, transmitting paging message or paging signals on each beam and across multiple TRPs of multiple cells by all gNBs in a 'tracking area' certainly generates significant radio signal overhead and occupies scared radio resources, which is clearly undesirable.

　　At NR-UE side, monitoring the control or scheduling channel (e.g. NR-PDCCHs) on each available beam for intended first paging signals requires the NR-UE to stay awake for long time and spend significant additional power on received signal processing.

　　There have been some attempts to reduce the overhead in transmitting paging messages and to reduce an NR-UE's processing by reducing the duration of NR-UE staying awake, as outlined below.

　　In one configuration, at the network side, periodic SS Bursts comprising SSBs and paging messages are transmitted on each beam and across multiple TRPs of multiple cells in the 'tracking area'. As such, the NR-UE may monitor the periodic SS Bursts for detectable TD-multiplexed SSBs or beams and thus only monitor visible beams for paging messages.

　　Such configuration may reduce the required signal-processing power at the NR-UE as a NR-UE only needs to stay awake during periodically scheduled SS Burst sets to detect SSBs and process the associated paging channels on the detected SSBs for intended paging messages. However, this configuration still has a high network processing overhead as the network needs to transmit first and second paging signals in every available SSBs and the NR-UE still needs to monitor all detected SSBs for an intended paging message. Furthermore, as the paging frames and paging occasions are coupled with the radio frames having scheduled SS Bursts and SS Bursts, paging is not versatile.

　　In another configuration, at the network side, periodic SS Burst sets and first paging messages are transmitted on a first channel on each beam and across multiple TRPs of multiple cells by all gNBs in a 'tracking area'. In such case, the first paging message can be transmitted in the SSBs or on separate channel outside the SSBs.

　　The network side then waits for beam reports from the NR-UEs who have detected the first paging message, and upon receipt of beam reports from one or more NR-UEs with the same group identity, the second paging message is transmitted on a second paging channel on the reported beams, across one or more TRPs of one or more cells by one or more gNBs in a 'tracking area' to all NR-UEs who have provided beam reports.

　　At the NR-UE, the first channels are monitored on each available beam, for an intended first paging signal. Upon detecting a positive group-ID e.g. NR-P-RNTI on a first channel, the best beam(s) are reported using a random access procedure for further reception of second paging on an associated second channel, noting that there will be multiple beam reports from multiple NR-UEs who have detected the same first paging message. The reported beam or beams are then monitored for the second paging signal.

　　This configuration may reduce network overhead in transmitting a second paging message to a number of NR-UEs and may reduce the signal processing power at individual NR-UEs in monitoring first channels for first paging signal and performing reception and decoding of associated second channel for intended second paging message. However, this option has high network access latency and additional signal processing required for random access in transmitting beam report.

　　As such, there are clearly problems associated with using LTE techniques as baseline paging procedure for NR multi-beam operation. As such, there is clearly a need for a more versatile solution which not only provide mechanism for reducing network overhead in transmitting first and second paging signal but also reduces the processing power required of an NR-UE.

　　It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.

　　The present invention is directed to method for use in NR systems, which may at least partially overcome at least one of the abovementioned disadvantages or provide the consumer with a useful or commercial choice.

　　With the foregoing in view, the present invention in one form, resides broadly in a method for use in a NR system comprising a plurality of gNBs and a plurality of NR-UEs, the NR-UEs configured to periodically wake up to monitor paging signals from the gNBs, the method comprising:
　　allocating, at a gNB of the plurality of gNBs, a resource pool which is associated with a NR paging frame for beam reporting from an intended NR-UEs or intended group of NR-UEs;
　　monitoring, at the gNB, the configured resource pool for one or more beam reports from one or more NR-UEs; and
　　transmitting, from the gNB and according to the one or more beam reports, paging signals which are directed to one or more in coverage NR-UEs.

　　The method may further comprise determining, at the gNB, a number of beams and a configuration of the beams to be serviced at TRPs of the gNB to achieve a desired coverage.

　　The method may further comprise, providing, by the gNB and to one or more in-coverage NR-UEs of the plurality of NR-UEs, a synchronization signal block (SSB), for time and frequency acquisition and beam measurement.

　　An NR-UE is configured to, upon waking, perform time and frequency acquisition and beam measurement base on the SSB.

　　The reports may comprise limited beam reports or full beam reports.

　　An NR-UE may be configured to perform contention for one or more channels in transmitting the beam report.

　　The resource pool may be associated with a NR-PF, and the NR-PF comprises one or more NR-POs, and an NR-UE is configured to transmit the beam report in the resource pool corresponding to an NR-PO of the one or more NR-POs.

　　The resource pools may be configured in radio frames prior to each associated NR-PF.

　　The gNB may be configured to perform beam sweeping on SSBs in response to receiving a paging initialisation from a Mobility Management Entity (MME).

　　The gNB may be further configured to allocate an instantaneous resource pool for beam reporting from the NR-UE, in a radio frame prior to an intended NR-PF in response to receiving the paging initialisation.

　　The resource pool may be associated with a NR-PF, and the start of the resource pool is defined with reference to the associated NR-PF.

　　The start of the resource pool may be defined with reference to the associated NR-PF by a predefined interval, which is less than or equal to 4ms.

　　The resource pool for beam reporting may be configured to comprise:
　　a first part, for indicating preferred beam indexes in limited beam reporting;
　　a second part for transmitting a full beam report; or
　　a first part, for explicitly indicating the presence of a transmitting beam report followed by associated second part for transmitting the beam report in full beam reporting.

　　The first part may be configured to comprise a single channel resource structure being semi-statically configured, by the gNB, to span at most one slot in time and a plurality of physical resource blocks (PRBs) in frequency, and is for transmitting preamble-like signatures from a plurality of NR-UEs that monitor a common NR-PF or one or more common NR-POs within a common NR-PF.

　　When limited beam reporting is configured, beam indexes may be mapped to predefined preamble-like signature indexes in the beam report.

　　The resource pool for beam reporting may comprise an indexed multi-sub-channel structure being semi-statically configured to span over at least one single slot of 14-symbols in time, and over plurality of resource blocks (RBs) in frequency, and to be used with a set of predefined DMRS sequences.

　　Sub-channels of the sub-channel structure may be indexed repeatedly, enabling a predefined number of retransmissions of a beam report.

　　An association between a sub-channel DMRS index and a preamble-like signature may be predefined.

　　The resource pool may be associated with a NR-PF, and the NR-PF may comprise one or more NR-POs, and the NR-POs may comprise a burst of paging slots spanning over an NR-PO interval which is defined for full beam sweeping on a paging message.

　　A gNB may be configured to determine a radio frame as a NR-PF based on the likelihood that at least one NR-UE in its coverage will monitor one or more NR-POs in that radio frame for intended paging signals upon waking-up.

　　The gNB may be configured to determine a likelihood of the NR-UE being in its coverage according to a shared NR-UE tracking database, which includes NR-UE information at initial network attachment and through periodic beam reporting.

　　Upon determining that the NR-UE is likely within its coverage but that servicing TRPs of the NR-UE are not known, full beam sweeping may be performed on paging signals on one or multiple NR-POs of the intended NR-PF from all associated TRPs.

　　Upon determining that the NR-UE is likely within its coverage and that the servicing TRPs of the NR-UE are known, full beam sweeping may be performed on paging signals on one or multiple NR-POs of the intended NR-PF from only the servicing TRPs.

　　Upon determining that the NR-UE is likely within its coverage, that the servicing TRPs of the NR-UE are known, and the beam reference of the NR-UE is up-to-date, partial beam sweeping may be performed on paging signals on one or multiple NR-POs of the intended NR-PF from only selected TRPs and on selected beams.

　　The gNB may be configured to:
　　determine that a paged NR-UE is not likely within its coverage; and
　　not perform beam sweeping on paging signals on NR-POs of the intended NR-PF of the paged NR-UE to minimise radio signals overhead and to conserve the transmit power.

　　The NR-UE may contend for sub-channels on the resource pool for a beam report transmission by randomly selecting a sub-channel index.

　　The NR-UE may randomly select a DRMS index from a configured set in generating a first DMRS sequence for use in the first selected sub-channel.

　　The NR-UE may use the selected sub-channel index and DMRS index for a first transmission of the beam report to derive the signature index indicating the presence of a beam report transmission basing on predefined associations.

　　In another sub-channel corresponding to the selected index, the NR-UE may randomly select another DRMS index from the same configured set to generate a second DMRS sequence for use in the subsequent retransmissions.

　　A NR-UE may be configured by its servicing gNB to use a compact format, a normal format, or an extended format for a full beam report.

　　The compact format comprises only a primarily preferred beam index or indexes.

　　An NR-UE ID specific masking CRC may be used with the compact format to identify a transmitter of the beam report.

　　The normal beam report format may comprise a primarily preferred beam index or indexes and an explicit NR-UE identifier.

　　The extended beam report format may comprise primarily and secondarily preferred beam indexes, and an explicit NR-UE identifier.

　　A CRC-attached, channel-encoded and rate-matched beam report may be masked with the assigned paging group identity, to enable interference randomisation to NR-UEs of different paging groups which may share the same beam reporting resource pool.

　　Embodiments of the present invention are directed to systems and methods for use in an advanced wireless communication system, such as the fifth generation (5G) or New Radio (NR) as being defined in 3GPP, with cloud radio interface providing optimal beam-formed paging services to plurality of new radio capable UEs (i.e. NR-UEs), through the dynamic and timely allocation of periodic and/or instantaneous resource pool for beam reports prior to dedicated beam-formed paging signals transmission.

　　In one embodiment of the present invention, a protocol for implementing at a gNB and plurality of in-coverage NR-UEs to realise low radio signal overhead and low power consumption paging in a multi-beam operational communication system is provided. An in-coverage NR-UE may be implicitly or explicitly triggered to report a beam reference to the servicing gNB for optimal transmission of further beam-formed paging signals (i.e. first and/or second paging signals) from the designated transmission-reception point (TRP) or TRPs, and further receive the intended or directed paging signals on the predetermined beam or beams reference at the NR-UE.

　　When implicit signalling is used, an in-coverage NR-UE may be required to wake up prior to a predetermined paging-frame (i.e. NR-PF) to reacquire time/frequency synchronisation, and within an unrestricted duration of time to monitor beam-swept reference signals such as periodic or instantaneous synchronisation signal blocks (SSBs) for beam measurement and report.

　　When explicit signalling is used, an in-coverage NR-UE may be required to wake up prior to a predetermined NR-PF to reacquire time-frequency synchronisation and within a restricted duration at the predetermined NR-PF or NR-PO to monitor a beam-swept paging indicator (i.e. first paging signal) as reference for beam measurement and upon a "positive detection" of a paging indicator perform beam reporting.

　　The beam-swept paging indicator (i.e. first paging signal) may be included as part of the periodic or instantaneous SSBs prior to a predetermined NR-PF. In both implicit and explicit methods, the gNB may timely allocate a resource pool for the NR-UEs which share the same NR-PF (implicit triggering method) or NR-UEs that share the same paging group identity e.g. P-RNTI (explicit triggering method), to indicate preferred beam indexes to the servicing gNB, or transmit beam report to the servicing gNB, or to indicate the presence of transmitting beam report and further transmit the beam reports to the servicing gNB.

　　The resource pool for beam reporting at NR-UE may be configured to comprise: only a first part (i.e. part 1) for limited beam reporting; only a second part (i.e. Part 2) for full beam reporting; or a first part (i.e. part 1) and an associated second part (i.e. part 2) for full beam reporting with number of blind decoding attempts reduction at the servicing gNB. The first part of the resource pool may be for indicating from a NR-UE and detecting at a gNB the preferred beam indexes or the presence of beam reports, where the second part of the resource pool is an UL grant free transmission resource pool for transmitting from a NR-UE and receiving at a gNB the beam reports. A resource pool for variety beam reporting formats may also be configured by a gNB, for use at the serviced NR-UEs, to associate with a NR-PF or a NR-PO of a NR-PF on which the paging message (i.e. first and second paging signal) or second paging signal directed to a NR-UE, is transmitted from the gNB.

　　In one embodiment of the present invention, where beam-swept SSBs is the reference signal for beam measurement or paging indicator for beam measurement is included as part of beam-swept SSBs to achieve optimal paging services, a NR-UE may assume that there is at least one SS burst set being transmitted in the radio frame prior to a predetermined NR-PF. In the case, the configured SS burst set periodicity is sparse, upon the arrival of a paging initialisation from the MME for a NR-UE in the coverage and in the absence of periodic SS Burst set, a gNB may locate the NR-UE and schedule an instantaneous SSBs in the radio frame prior to the NR-PF as reference for beam measurement at the NR-UE(s). Depending on whether the NR-UE location is known, the gNB may perform full beam sweeping at all TRPs, partial beam-sweeping at selected TRPs or beam-formed transmission on instantaneous SSBs at selected TRP or TRPs. In the same radio frame, the gNB may further allocate an associated resource pool for beam reporting at plurality of NR-UEs.

　　In another embodiment of the present invention, the first part of a resource pool for beam reporting is single channel resource structure spanning at most one slot in time and plurality of physical resource blocks (PRBs) in frequency for transmitting preamble-like signatures from plurality of NR-UEs. Where the said NR-UEs may monitor the same NR-PF for paging signal in the limited beam reporting option or share the same second part of a resource pool in transmitting beam reports in full beam reporting option. The second part of a resource pool (i.e. UL-grant free transmission resource) associated with a predetermined NR-PF for concurrent beam reporting at plurality of NR-UEs, is a multi-channel structure that is configured by a gNB to span across at least one slot in time and plurality of resource blocks (RBs) within the paging bandwidth in frequency. The start of a resource pool for beam reporting and the start of the corresponding NR-PF or corresponding NR-PO is separated by ms where is predefined and fixed to assist the implicit indication of a configured resource pool for beam reporting. The gNB may further configure a set of predefined and indexed orthogonal DMRS sequences, to be used in associating with a configured multi-channels grant free resource pool structure.

　　Furthermore, sub-channels within a configured grant free resource pool for beam reporting may be indexed repeatedly to enable predefined number of retransmissions of a beam report. A sub-channel's index and a DMRS index in the second part of a resource pool are said to associate with a preamble-liked signature the first part of a resource pool. This enable a gNB, upon successful detection of a signature in the first part of a resource pool, to identify the sub-channel and DMRS indexes for the reception and decoding of the associated beam report's first transmission in the second part of a resource pool. When a NR-UE has a beam report to transmit on a resource pool, the NR-UE may firstly randomly select a sub-channel index for the mapping of the first transmission and corresponding retransmissions. Corresponding to each sub channel of a selected index, the NR-UE may further randomly and independently select DMRS index for an orthogonal DMRS sequence generation and mapping to assist the demodulation of a beam report at the gNB. With the selected sub-channel index and DMRS index for the first transmission, the NR-UE may further identify the preamble-liked signature for transmission in the first part of the resource pool in the full beam reporting option with number of blind decoding attempt reduction. In the limited beam reporting option, when a NR-UE has a beam report to transmit on a resource pool, the NR-UE may select the signature index corresponding to index of the preferred beam for preamble-like sequence generation and transmission. There may be up-to 64 indexed signatures corresponding to 64 predefined beam indexes, and multiple NR-UEs monitoring the same NR-PF, may select the same signature index for preamble like sequence generation and transmission in a configured single-channel resource for beam indexes indication.

　　In further embodiment of the present invention, variety of beam report formats are defined and indicated for use at a NR-UE. The beam report formats include: a 'compact format' for very short beam report payload having only primary beam information to inform the servicing gNB the beam that the NR-UE prefers to receive its paging signals; a 'normal format' for standard beam report payload having primary beam information to inform the servicing gNB the beam that the NR-UE prefers to receive its paging signals, and explicit NR-UE ID to indicate to the servicing gNB the NR-UE that the beam report belongs to; and an 'Extended format' for extended beam report payload having primary beam information and secondary beams information to inform the servicing gNB the beam that the NR-UE mostly prefers, and other beams that the NR-UE is capable to monitor for the reception of its paging signals, and explicit NR-UE ID to indicate the NR-UE that the beam report belongs.

　　The extended format gives the gNB the flexibility in scheduling a beam or beams in transmitting paging signals to multiple NR-UEs that may share the same beam or same set of beams.

　　According to embodiments of the present invention, in enabling a gNB to identify a beam report's transmitter when the 'compact format' beam report is configured for use, the channel coding structure with UE specific CRC masking technique is mandate, where a gNB will perform blind-decoding and identify the NR-UE for a beam report. The channel coding structure with UE specific CRC masking technique can also be used on 'normal format' and 'Extended format' of beam report. The use of channel coding structure with UE specific CRC masking technique on 'normal format' and 'Extended format' will further improve the error detection of a transmitted beam report. Furthermore, the channel coding structure for the 'compact format', 'normal format' and 'Extended format' also include paging group ID (i.e. P-RNTI) masking function prior to the modulation function to randomise the interference to the signals from NR-UEs in other paging groups.

　　Any of the features described herein can be combined in any combination with any one or more of the other features described herein within the scope of the invention.

　　The reference to any prior art in this specification is not, and should not be taken as an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge.

　　Various embodiments of the invention will be described with reference to the following drawings, in which:

Fig. 1 is illustrates a paging message structure, according to LTE, and as adapted for 5G or NR technology;

Fig. 2 is schematically illustrates a paging structure, for use in new radio (NR) multi-beam operation, according to an embodiment of the present invention;

Fig. 3A illustrates an exemplary method, for use in dense SS Burst set transmission, according to an embodiment of the present invention; Fig. 3B illustrates an exemplary method, for use in dense SS Burst set transmission, according to an embodiment of the present invention; Fig. 3C illustrates an exemplary method, for use in dense SS Burst set transmission, according to an embodiment of the present invention;

Fig. 4A illustrates an exemplary method, for use in sparse SS Burst set transmission, according to an embodiment of the present invention; Fig. 4B illustrates an exemplary method, for use in sparse SS Burst set transmission, according to an embodiment of the present invention; Fig. 4C illustrates an exemplary method, for use in sparse SS Burst set transmission, according to an embodiment of the present invention;

Fig. 5 illustrates a grant free resource pool structure, associated with single NR-PO and multiple NR-POs, according to an embodiment of the present invention;

Fig. 6 illustrates a grant free resource pool structure, associated with an NR-PF, according to an embodiment of the present invention;

Fig. 7 illustrates a resource structure, associated with an NR-PF for limited beam indication from a group of NR-UEs, according to an embodiment of the present invention;

Fig. 8 illustrates an enhanced beam reporting resource structure, for complexity reduction at a gNB receiver, according to an embodiment of the present invention; and

Fig. 9 illustrates a coding structure for beam report formats, according to an embodiment of the present invention.

　　Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way.

　　Fig. 2 schematically illustrates a paging structure 50, for use in new radio (NR) multi-beam operation, according to an embodiment of the present invention. The structure 50 enables reduced radio traffic overhead when transmitting paging messages (i.e. first and second paging signals) at gNBs in a tracking area.

　　In particular, gNBs in tracking areas identify the presence of, record, and track NR-UEs on an individual or group basis depending on the beam reporting method being used, and within spatial areas at transmission and reception points (TRPs). NR-UEs are then identified for receiving dedicated beam-formed paging messages from a designated TRP or TRPs and on a preferred beam of the NR-UEs.

　　The paging structure 50 allows an NR-UE to sleep or be inactive most of the time and to wake up at predefined intervals prior to a predefined paging frame (i.e. NR-PF) or a paging occasion (NR-PO) in the NR-PF. The NR-UE may then reacquire frequency and time synchronisation, as time and frequency drifting is likely to happen at very high frequency bands, decide beam references or preferred beams indexes, report beam references or preferred beam indexes to its servicing gNB with or without being triggered, and then monitor the beams that it prefers for paging signals transmission and reception, hence conserving the processing power of the NR-UE and reducing the time it stays awake.

　　The paging structure 50 comprises two or more consecutive radio frames 70, 60. The second of the two or more consecutive radio frame (n) 60 may be one of the predefined NR paging radio frames (NR-PFs) for NR-UEs having a derived NR-PF 61 in monitoring paging information or paging messages from a servicing NR network. The NR-PF 61 further comprises one or more NR paging occasions (NR-POs) 62, 63, 64, 65, wherein each NR-PO comprises a burst of consecutive and/or non-consecutive paging slots 66 spanning over an NR-PO interval 68 being defined for partial or full beam sweeping in a paging message transmission at a designated TRP.

　　There are at most two beam-formed paging messages that are time-division multiplexed in one slot of 14 symbols, and each paging message is scheduled and transmitted on an NR-PDCCH 66.1 and an associated NR-PDSCH 66.2 respectively.

　　The radio frame (n-1) 70, which is located immediately prior to the NR-PF 61, comprises one interval of multi-slots 74 for periodic or instantaneous synchronisation signals and minimum system information (MSI) beam sweeping (i.e. synchronisation signal blocks (SSBs) and an SS burst set), and another interval of one or multiple slots 71 for limited or full beam reporting. The interval for beam reporting 71 comprises: a first single channel resource for limited beam reporting (i.e. indicating the preferred beam index); a second multi-channel UL grant free transmission resource pool for transmitting beam reports; or a first single channel resource for indicating the presence of beam reports and an associated second multi-channel grant free transmission resources pool for transmitting beam reports.

　　The interval for beam reporting is implicitly and timely configured for use in transmitting beam report indications and/or beams reports to a servicing gNB by the NR-UEs that will monitor NR-

POs

62, 63, 64 65 in the NR-PF 61 for directed paging message.

　　The periodic or instantaneous SSB beam sweeping 74 is to assist a NR-UE to re-acquire frequency and time synchronisation after a long sleeping time or inactive time. The SSB beam sweeping also provides information to the NR-UE for measurement and determination of a beam or a set of beams that it prefers for paging message receptions at its location. The reference can be the beam or set of beams with the best SINR measured at an NR-UE.

　　The NR-UE indicates the preferred beam index or the presence of a beam report and/or reports the preferred beam(s) in an allocated resource pool 71 and then monitors one or more beams of one or multiple NR-

POs

62, 63, 64, 65 in the corresponding NR-PF 61 for directed paging messages.

　　The preferred beam information reported by a NR-UE on an indicated resource pool at a paging cycle allows the gNB to identify the presence of the NR-UE, and record and track that NR-UE for efficient paging process in multi-beam operation. A resources pool for beam reporting 71 corresponding to a NR-PF 61 starts ' 'ms 73 prior to the start 67 of the first NR-PO 62 in the corresponding NR-PF 61. The offset ' ' may be fixed to a nominated value regardless of the numerology used for paging messages transmission, and is preferably set to 4ms to enable an implicit indication thereof.

　　The time duration of a resource pool for beam reporting is configurable, spanning over ' ' ms 72, where the period ' ' varies according to the numerology used for paging messages transmission. It is preferred that ' ' is configurable to span at least over one slot of 14 symbols regardless of configured numerology for paging message transmission/reception.

　　Based on a non-restricted observation time of ' ' ms 75, which ends ' ' ms 76 before the start 77 of a resources pool 71, the NR-UE initially monitors the periodic and/or instantaneous SS burst set 74 for time/frequency re-synchronisation and beam measurement, prior to the monitoring of one or more NR-

POs

62, 63, 64, 65 in the associated NR-PF 61 for directed paging messages. The term ' ' also varies according to the numerology used for paging messages transmission and is preferably equivalent to 2 to 4 symbols duration regardless of configured numerology.

　　In order to realise the above-mentioned paging in a NR multi-beam system, corresponding procedures, designs and methods are described below. In particular, procedures for use at a servicing gNB and serviced NR-UEs are exemplarily illustrated in Fig. 3A, Fig.3B, Fig.3C, Fig.4A, Fig.4B, and Fig.4C; the design of multi-channels grant free transmission resource pool for full beam reporting from plurality of NR-UEs is exemplarily illustrated in Fig. 5, a method of reporting for meeting required reliability is exemplarily illustrated in Fig. 6, an enhanced resource pool for limited and full beam reporting to reduce complexity at a receiver of a gNB is exemplarily illustrated in Fig. 7 and Fig.8; and beam reporting formats and channel coding structures for use in full beam reporting are exemplarily illustrated in Fig. 9.

　　The periodicity of beam sweeping for SSBs transmission or SS Burst set transmission is configurable can be dynamically selected. The periodicity may be selected from the set of [5ms, 10ms, 20ms, 40ms, 80ms and 160ms].

　　Since the SS Burst set periodicity is configurable, it may be configured so that the periodicity is sufficiently dense so that at time a NR-UE waking up, there is at least one periodically scheduled SS Burst set for the NR-UE to perform time/frequency re-acquisition and beam measurement (e.g. 5ms, 10ms, or 20ms), as is exemplarily illustrated in Fig. 3A, Fig.3B, and Fig.3C.

　　Fig. 3A, Fig.3B, and Fig.3C illustrate an exemplary method 100, for use in dense SS Burst set transmission, according to an embodiment of the present invention. The method 100 is performed at a servicing gNB 110 and at a serviced NR-UE 150, individually and through interaction 102 therebetween.

　　Initially, periodic beam sweeping is performed on SSBs at the gNB 110 in step 111, which provides beam-formed synchronisation signals and minimum system information (MSI) for time/frequency acquisition at the NR-UE 150 upon wake up. A periodic configured resource pool, corresponding to a periodic SS Burst set, for beam reporting associating with a NR-PF for NR-UE in the coverage may also be provided. The gNB periodically monitors the resource pool for limited beam reports or full beam reports with or without beam report indications in step 113.

　　A record for the NR-UE is entered in an NR-UE location database at step 114 upon its registration and is then tracked (and the database updated) as long as it remains at the same location where it may not need to provide periodic beam reports or performs periodic or semi-periodic beam reporting. A big data analytic engine may be implemented to predict and pin-point the NR-UE's location down to the TRP's level for dedicated beam-formed services upon a paging initialisation from the Mobility Management Entity (MME).

　　Upon receiving a paging initialisation from the MME, as illustrated in step 115, the gNB 110 checks the likelihood that the paged NR-UE is within its covering spatial area. If the paged NR-UE is not likely within its spatial area, as illustrated by 116, the gNB terminates the paging process by ignoring the paging initialisation in step 117. If the paged NR-UE is likely within its spatial area 118, and the precise NR-UE location is not known, as illustrated by 119, the gNB performs full beam sweeping on paging message by transmitting 1st and 2nd paging signals on every available beams in all cells within its control, in step 120.

　　If the paged NR-UE is likely within its spatial area, as illustrated by 118, and the precise NR-UE location is known, as illustrated by 121, the gNB further checks whether the NR-UE's beam reference is received and up-to-date. If the location of the paged NR-UE is known, as illustrated in step 121, and the beam reference of the NR-UE is not up-to-date or not received, the gNB may perform full beam sweeping on paging message at selected cell on selected TRP or TRPs in step 123. If the location of the paged NR-UE is known, as illustrated by 121, and the beam reference of the NR-UE is received and up-to-date, as illustrated by 124, the gNB performs paging message transmission at selected TRP or TRPs on only selected beams in step 125.

　　Correspondingly, the serviced NR-UE 150 starts in a 'sleeping' state, as illustrated by step 151, where the expiry of DRX-timer, as illustrated by 153, causes the NR-UE to 'wake-up' in step 154, which occurs prior to an incoming NR-PF. In the radio frame(s) immediately prior to a NR-PF, the NR-UE monitors and detects beam-formed SSBs in a periodically scheduled SS burst set in step 155, to be able to reacquire frequency and time synchronisation as well as MSI for paging message monitoring.

　　In the case that the NR-UE can resolve the beam or the set of beams that it prefers for paging message reception in the incoming NR-PF after the completion of a SS Burst set reception and decoding, as illustrated in 156, the NR-UE selects a signature index corresponding to the preferred beam index for preamble-like sequence generation and transmission in the configured resource pool associating with an incoming NR-PO or NR-POs, in an incoming NR-PF to its servicing gNB, in step 157 in case limited beam reporting is configured. If full beam reporting is configured, the NR-UE may contend for a sub-channel or multiple of sub-channels having the same channel index, for transmitting beams report, or beam report indication followed by beam reports to its servicing gNB in step 157.

　　In the NR-PO or NR-POs in the NR-PF, the NR-UE further monitors the first physical channels only on the recently reported beam(s) for intended first paging signal in step 158. Otherwise, in the case that the NR-UE cannot resolve the beam or the set of beams for reporting to its servicing gNB, as illustrated by 159, the NR-UE does not send referent beam report to the gNB, but instead monitors, in the NR-PO or NR-POs in the NR-PF, the first physical channels on the available beam according to its knowledge for intended first paging signal in step 160.

　　If there is no positive first paging signal detected, as indicated by 161, the NR-UE may go back to sleep in step 151. If, on the other hand, the NR-UE detects a positive first paging signal on one or more beam-formed first physical channel, as illustrated by 162, the NR-UE further demodulates the associated second physical channels on the beam(s) where the intended first physical channel(s) is/are detected, as illustrated in step 163.

　　If the demodulation and decoding of all associated beam-formed results at no paging message being directed to it, as illustrated by 164, the NR-UE will go back to sleep in step 151. Otherwise, the demodulation and decoding of all associated beam-formed results in at least one paging message being directed to it, as illustrated by 165, and the NR-UE initiates a tailored random access procedure in step 105 for further call establishment.

　　As outlined above, SS Burst set periodicity is configurable, and as such may also be sparse (e.g. 40ms, 80ms, or 160ms). As such, when an NR-UE wakes up, there may be no periodically scheduled SS Burst set in the radio frame(s) immediately prior to an incoming NR-PF or incoming NR-PO as reference signals for the NR-UE to perform time/frequency re-acquisition and beam measurement.

　　Since the gNB may have no reliable record of the presence and/or location of the NR-UE, it performs full beam sweeping on a paging message upon the arrival of a paging initialisation from the MME. In order to reacquire time and frequency synchronisation prior to paging information monitoring, a NR-UE either uses other signals as reference, or stays awake for a longer time e.g. up to 160ms or 16 radio frames, and spends additional or extra signal processing power searching for a periodically scheduled SS burst set. This leads to a more complex design at a NR-UE as different paging procedures for use at a NR-UE have to be applied to different configured SS Burst set periodicity.

　　In order to reduce radio signal overhead in paging message transmission and/or to simplify NR-UE design, an instantaneous SS burst set transmission is utilised upon an arrival of a paging initialisation from the MME or when a gNB need to obtain location updates from targeted NR-UEs. The instantaneous SS burst set transmission prior to the targeted NR-PF assists a NR-UE in re-acquiring time/frequency synchronisation, and allows a gNB to collect beam reports from targeted NR-UEs within its coverage for location tracking, and importantly to enable a unified and simple paging procedure for use at NR-UE. This case is exemplarily illustrated in Fig.4A, Fig.4B, and Fig.4C.

　　Fig.4A, Fig.4B, and Fig.4C illustrate an exemplary method 101, for use in sparse SS Burst set transmission, according to an embodiment of the present invention. The method 101 is performed at the servicing gNB 110 and the serviced NR-UE 150, similar to the method 100 of Fig. 3A, Fig.3B, and Fig.3C.

　　Initially, periodic beam sweeping is performed on SSBs at the gNB 110 in step 111, and beam-formed synchronisation signals and MSI are provided to the NR-UE in 111.1.

　　The record of the NR-UE is entered into the NR-UE location database in step 114 upon its registration and is then tracked (and the database updated) as long as it remains at the same location where it may not need to provide periodic beam reports or performs periodic or semi-periodic beam reporting. The big data analytic engine running on the NR-UEs' location database 114 may predict and pin-point the location of the NR-UE down to the TRP for dedicated beam-formed services including instantaneous beam-sweeping on synchronisation signals and MSI to assist beam measurement at a targeted NR-UE.

　　Upon receiving a paging initialisation from the MME, or when gNB needs to collect beam reports from targeted NR-UEs within its coverage, the gNB may utilise the database 114 to check the likelihood that the paged NR-UE is within its covering spatial area. If the paged NR-UE is not likely in its spatial area, as illustrated by 116, the gNB terminates the paging process by ignoring the paging initialisation, as illustrated in step 117.

　　If the paged NR-UE is likely in its spatial area, as illustrated by 118, and the precise NR-UE location is not known, as illustrated by 119, the gNB performs full beam sweeping on instantaneous synchronisation signals and MSI at every cells and TRPs within its control in the radio frame prior to the NR-PF associated with the NR-UE, as illustrated in step 130.

　　The gNB then follows up with monitoring of intermediately configured resource pool associated with the NR-PF for limited beam reports or full beam reports of the NR-UE with or without beam report indications in step 131. If the NR-UE beam reference is not received, as illustrated by 132, the gNB performs full beam sweeping on paging message transmission by transmitting 1st and 2nd paging signal on every available beams from all cells and TRPs within its control in step 133. If the NR-UE beam reference is received, as illustrated by 134, the gNB updates the NR-UE tracking database and transmits beam-formed paging message only at selected cell and from selected TRP or TRPs on selected beams, as illustrated in step 135.

　　If the paged NR-UE is likely in its spatial area, as illustrated by 118, and the precise NR-UE location is known, as illustrated by 121, the gNB performs full beam sweeping on instantaneous synchronisation signals and MSI at selected cell and/or at selected TRP or TRPs in the radio frame prior to the NR-UE's NR-PF in step 140. The gNB then follows up with monitoring of intermediately configured resource pool corresponding to the NR-UE's NR-PF for NR-UE's beam reports in step 141. If the NR-UE beam reference is received, as illustrated by 144, the gNB updates the NR-UE tracking database in step 114, and transmits beam-formed paging message at selected TRP or TRPs on selected beams in step 135. If the NR-UE's beam reference is not received, as illustrated by 142, the gNB may perform full beam sweeping on paging message at selected cell or cells and TRP or TRPs as step 143.

　　As was the case for the method 100, the serviced NR-UE 150 starts in 'sleeping' state 151, where the expiry of a DRX-timer, as illustrated by 153, brings the NR-UE to 'wake-up' state, as illustrated in step 154, prior to an incoming NR-PF. In the radio frame(s) immediately prior to the NR-PF, the NR-UE monitors and detect beam-formed SSBs in a periodically scheduled SS burst set, and is able to reacquire frequency and time synchronisation as well as MSI for paging message monitoring in step 155.

　　In case the NR-UE can resolve the beam or the set of beams that it prefers for paging message reception in the incoming NR-PF, as illustrated in 156, after the completion of a SS burst set reception and decoding, the NR-UE selects a signature index corresponding to the preferred beam index for preamble-like sequence generation and transmission in the configured resource pool associating with an incoming NR-PO or NR-POs, in an incoming NR-PF to its servicing gNB, as illustrated in step 157. If the option of full beam reporting is configured for use, the NR-UE may then contend for a channel, in the configured resource pool for beam reporting associating with an incoming NR-PO or NR-POs, in an incoming NR-PF for transmitting beams report, or beam report indication followed by beams report to its servicing gNB, as illustrated in 157. In the NR-PO or NR-POs in the NR-PF, the NR-UE further monitors the first physical channels only on the reported beam(s) for intended first paging signal, as outlined in step 158.

　　Otherwise, in the case that the NR-UE cannot resolve the beam or the set of beams for reporting to its servicing gNB, as illustrated by 159, the NR-UE will not send a reference beam report to the gNB, but instead monitor, in the NR-PO or NR-POs in the NR-PF, the first physical channels only on available beam according to its knowledge for intended first paging signal, as outlined in step 160.

　　If there is no positive first paging signal detected, as illustrated by 161, the NR-UE goes back to sleep in step 151. If the NR-UE detects positive first paging signal on one or more beam-formed first physical channel, as illustrated by 162, the NR-UE further demodulates the associated second physical channels on the beam(s) where the intended first physical channel(s) is/are detected, in step 163. If the demodulation and decoding of all associated beam-formed results at no paging message being directed to it, as illustrated by 164, the NR-UE will go back to sleep in step 151. Otherwise, upon the demodulation and decoding of all associated beam-formed results in at least one paging message being directed to it, as illustrated by 165, the NR-UE will initiate the tailored random access procedure in step 105 for further call establishment.

　　Another embodiment of the present invention relates to a resource pool for use by plurality of NR-UEs in transmitting preferred beam information, i.e. beam reports to the servicing gNB, which is exemplarily illustrated in Fig. 5.

　　Fig. 5 illustrates a grant free resource pool structure 200, associated with single NR-PO and multiple NR-POs, according to an embodiment of the present invention. The resource pool structure 200 may be configured as an UL grant-free transmission resource pool to associate with a single NR-PO 210, or multiple NR-POs 220.

　　When the UL grant-free transmission resource pool is associated with a single NR-PO, as illustrated by configuration 210, the grant-free resource pool 212 associated with a NR-PO 201 is implicitly identified by the NR-PO 201 through a predefined offset 'k' 202. The offset 'k' 202 indicates the time distance between the start of the grant-free resource pool 212 to the start of the corresponding NR-PO 201. Both the NR-PO 201 and its associated grant-free resource pool 212 are confined within the same radio frame 211.

　　The grant-free resource pool for full beam reporting 212, which is associated with a single NR-PO 201, can be used only by the NR-UEs that have been configured to monitor the NR-PO 201 for potentially directed paging message. The grant-free resource pool 212 is configurable to span at least over one single slot of 14-symbols in time 204 and over a plurality of resource blocks (i.e. RBs) in frequency within the bandwidth of paging message transmission 203, and further to comprise plurality of indexed sub-channels.

　　When there is a beam report for transmitting in a grant-free resource pool, the NR-UE contends for a channel by randomly select a

DMRS index

213, 214, 215 for DMRS sequence generation and RE mapping to a selected slot.

　　When an UL grant-free transmission resource pool is associated with multiple NR-POs, as illustrated in configuration 220, the grant-free resource pool 222 associated with the multiple NR-

POs

201, 223 is implicitly indicated with reference to the NR-

POs

201, 223 with the predefined offset 'k' 202. The offset 'k' 202 indicates the time distance between the start of the grant-free resource pool 222 to the start of the corresponding first NR-PO 201. Both NR-

POs

201, 223 and their associated grant-free resource pool 222 are confined within the same radio frame 221.

　　The grant-free resource pool for full beam reporting 222 which is associated with multiple NR-

POs

201, 223 can be used only by the NR-UEs that have been configured to monitor those NR-

POs

201, 223 for potentially directed paging message. A grant-free resource pool 222 associated with multiple NR-

POs

201, 223 is configurable to span at least over multiple slots of 14-symbols in time 204 and over plurality of resource blocks (i.e. RBs) in frequency within the bandwidth of paging message transmission 203, and further to comprise plurality of indexed sub-channels.

　　When there is a beam report for transmitting in a grant-free resource pool, the NR-UE contends for a channel by randomly select a time-indexed sub-channel and further select a

DMRS index

223, 224, 225 for generating DMRS sequence and RE mapping to the selected slot/sub-channel.

　　Fig. 6 illustrates a grant free resource pool structure 250, associated with an NR-PF, according to an embodiment of the present invention. The grant-free resource pool 270 is associated with a NR-PF 251 which is implicitly indicated via the implicit indication of the NR-PF 251 with the predefined offset 'k' 260. The offset 'k' (260) indicates the time distance between the start of the grant-free resource pool 270 to the start of the first NR-PO 252 in the corresponding NR-PF 251. The associated grant-free resource pool 270 is confined within the radio frame 261 which is immediately prior to the NR-PF 270.

　　The grant-free resource pool for full beam reporting 270, associated with plurality of NR-

POs

252, 253, 254, 255 of a NR-PF 251, can be used only by the NR-UEs which have been configured to monitor one or multiple NR-

POs

252, 253, 254, 255 for potentially directed paging messages. The grant-free resource pool 270 associated with the NR-PF 251 is configurable to span over multiple 14-symbol slots in time 204 and over plurality of resource blocks (i.e. RBs) in frequency within the bandwidth of paging message transmission 203. In order to accommodate a high number of simultaneous beam reports from a plurality of NR-UEs sharing the same resource pool, a grant-free resource pool 270 is configured to comprise plurality of time-

frequency sub-channels

273, 275, 275, 276. A time-frequency sub-channel 273 may span over 1/2 of a slot (i.e. 7 symbols 271) and y RBs. The time-frequency sub-channels within the grant-free resource pool 270 may be indexed repeatedly (i.e. 275 and 276, or 273 and 274) for the transmission of multiple copies of a beam-report to improve the reception reliability in a resource sharing environment.

　　When there is a beam report 301 for transmitting in a grant-free resource pool 270, the NR-UE contends for sub-channels by: a) randomly selecting a time-frequency sub-channel index (e.g. index ' ' 275 and 276); b) randomly selecting first DMRS index 281 in the configured DMRS indexes set 280 for generating first DMRS sequence in transmitting the first copy of the beam report 275; and c) randomly selecting second DMRS index 282 in the configured DMRS indexes set 280 for generating second DMRS sequence in transmitting the second copy of the beam report 277.

　　Independent selection of DMRS indexes for the first and second transmission will further resolve collision in case where two or more NR-UEs sharing the same NR-PF, concurrently select the same time-frequency sub-channel for their beam report transmission.

　　Alternatively, a resource pool for beam reporting may be configured as single channel resource for limited beam reporting (i.e. implicitly indicating the preferred beam indexes without transmitter's UE-ID). Fig. 7 illustrates the alternative resource structure 230, associated with an NR-PF for limited beam indication from a group of NR-UEs, according to an embodiment of the present invention.

　　The resource for limited beam reporting 232, associated with a NR-PF 231 or NR-

POs

201, 233 within a NR-PF 231, can be used only by the NR-UEs which have been configured to monitor one or multiple NR-POs 201, 233s in a NR-PF 231 for potentially directed paging messages. The resource for limited beam reporting 232 associated with a NR-PF 231 is the single channel resource for preamble-like signatures transmission and being configured to span over (e.g. at most) one 14-symbol slot in time 232 and over plurality of resource blocks (i.e. RBs) in frequency within the bandwidth of paging message transmission 203. Each unique signature index directly corresponds to a unique beam index. There may be up-to 64 indexed signatures corresponding to 64 beam indexes pre-determined for use, and multiple NR-UEs may select the same signature index for preamble-liked sequence generation and transmission in a configured single-channel resource for beam indexes indication. When there is a limited beam report for transmitting in a single channel resource, a NR-UE select the signature index corresponding to the preferred beam index for preamble-liked sequence generation and RE mapping to the configured single-channel resource.

　　When a resources pool, such as the resource pool 71 in Fig. 2, is for limited beam reporting and comprises only single-channel resource, a gNB is not able to locate a track NR-UE on individual basis. The gNB is only able to locate the group, that an intended or targeted NR-UE may belong to, according to predetermined conditions or functions, for sub-optimum paging signals transmission.

　　When a resources pool for full beam reporting comprises only multi-channels grant free transmission resources, a gNB needs to perform a number of blind-decoding attempts in detecting an intended beam report and retrieve its content e.g. preferred beams and NR-UE-ID. Furthermore, beam reporting using UL grant free transmission may induce additional complexity at the gNB's receiver due to imperfect UL synchronisation at NR-UE in IDLE mode i.e. UL transmission without gNB's assigned timing advance (TA).

　　In an attempt to reduce complexity at gNB's receiver, the resources pool for beam reporting may be enhanced, as outlined below. Fig. 8 illustrates an enhanced beam reporting resource structure 400, for complexity reduction at a gNB receiver, according to an embodiment of the present invention.

　　The structure 400 includes a first part (Part 1) 410 of the beam reporting resources pool 71 which is single channel resource structure (i.e. like the one used for limited beam reporting) spanning at most one slot in time 420 and plurality of physical resource blocks (PRBs) in frequency 430. The structure further includes a second part (Part 2) 450 of a beam reporting resources pool 71 which is the multi-channels grant free transmission resource structure. The Part 1 410 of the resources pool is for indicating from plurality of NR-UEs and detecting a gNB the presence of beam reports being transmitted in the associated part 2 of the resource pool, where the Part 2 450 of the resource pool is for transmitting from plurality of NR-UEs and receiving at a gNB beam reports.

　　When configured, a plurality of NR-UEs sharing the same part 2 450 of a resource pool in transmitting beam reports 451, 452, 453, firstly transmit preamble-like

unique signatures

411, 412, 413 in the part 1 410 of a resource pool. A defined signature is mapped within the first part of the slot leaving some guard-time (GT) 415 at the end of the slot. Depending on the position of the NR-UE relatively to the servicing TRP of the gNB, a transmitted signature may arrive at the TRPs of the gNB at any time within the slot leaving different GT values where all transmitted preamble-liked signatures from plurality of NR-UEs at different positions are arrived at the gNB receiver within the defined received window 420.

　　A transmitted

signature

411, 412, 413 in the part 1 410 of a resource pool explicitly indicates to the gNB the presence of a transmitting beam report and implicitly indicating the sub-channel index and associated DMRS index being used in the a first

beam report transmission

451, 452, 453. The association between the combination of a sub-channel index and a DMRS index used for the first beam report transmission and a signature are predefined to assist the implicit indication of the sub-channel index and DMRS index upon the reception of a defined signature.

　　Upon a positive detection of a defined signature in the part 1 410 of a resource pool, the gNB further derives a sub-channel index and DMRS index from a predetermined associations for the reception of the corresponding beam report's first transmission. When the first transmission of the beam report is not resolvable due to collision, the gNB may perform a limited number of blind decoding on the subsequent transmission e.g.

second transmission

461, 462, 463 with the same sub-channel index in an attempt to successfully decode a beam report. It should be noted that a collision on a beam report's first transmission also results in more than one NR-UEs using the same signature to indicate the presence of their transmitting beam reports.

　　A beam report 301 for being transmitted in a resource pool may comprise explicit preferred beam 303 or preferred set of

beams

303, 304, and implicit or explicit NR-UE ID 302 which is then channel-encoded and rate-matched before being further scrambled with the paging group identity (e.g. NR-P-RNTI 305).

　　Fig. 9 illustrates a coding structure 300 for beam report formats, according to an embodiment of the present invention. The coding structure comprises three beam report formats, as follows.

　　Firstly, a 'Compact format' 311 is provided comprising only primary preferred beam information 303, indicating the beam that a NR-UE prefers to receive its paging message in the incoming NR-PO or NR-PF. This format has the smallest payload size of the formats, and is configured for use when there are high number of NR-UEs which potentially share the same grant-free resource pool with high number of time-frequency sub-channels of low REs per sub-channel for beam reporting, or if there is a needs for high reliability in reception of a beam report with ultra-low coding rate.

　　A 'Normal format' 312 comprises an explicit NR-UE-ID field 302 and the primary preferred beam information 303 indicating the beam that a NR-UE prefers to receive its paging message in the incoming NR-PF.

　　An 'Extended format' 313 comprises the explicit NR-UE-ID field 302, the primary preferred beam information 303, and secondary preferred beam information 304, indicating the other beams that a NR-UE secondarily prefers to receive the same paging message in the incoming NR-PF. The set of primary and secondary

preferred beam information

303, 304 may form a spatial beam-sweep in paging message transmission catering for NR-UE mobility.

　　The entire

beam report payload

311, 312, 313 for transmission is used to calculate the CRC parity bits at a 'CRC parity bits calculation' function 314, which may be then scrambled with the transmitter's NR-UE-ID 302 to generate NR-UE-ID specific masking CRC parity bits at a "UE specific CRC masking" function 315.

　　The NR-UE specific masking function 315 is mandatory for the transmission of beam report using the compact format, however, is optional for the transmission of beam report using the normal or extended format to reduce the blind decoding processing power at the beam reports receiver (i.e. gNB).

　　The computed CRC parity bits are attached to the beam report payload at CRC-attachment function 310 for further channel encoding and rate matching at the "channel-coding & rate-matching" function 320.

　　In order to randomise the interference to the signals from NR-UEs in other paging groups, the rate-matched code word of a beam report is scrambled with the scrambling sequence at a "scrambling" function 330 where the scrambling sequence is generated by initialising the "scrambling sequence generator" 331 with the paging group ID i.e. NR-P-RNTI 305.

　　The paging group ID scrambled code word of a beam report is then modulated, layer-mapped and precoded at a "Modulation/Layer mapping/Precoding" function 340 to generate the sequence of complex-value precoded symbols for further RE mapping into the selected sub-channel.

　　With the selected DMRS index or indexes 307, the DMRS sequence or sequences are generated using DMRS sequence generator function 351, and together with the generated the sequence of complex-value precoded symbols, they are mapped into the sub-channels indicated by the selected time-frequency sub-channel index 306 for further generating RF TX signals 308 at the "UL TX signals generation" function 360.

　　Embodiments of the present invention provide resource pool designs for beam reports which may associate with potential NR paging frame or associate with beam sweeping on paging indications.

　　Some embodiments provide a single channel resource for explicitly indicating the preferred beam index from a NR-UE. In particular, multiple NR-UEs with UE-IDs satisfying some predetermined conditions or functions may use the same preamble-like signature to indicate their preferred beams to the servicing gNB in the same configured single channel resource for sub-optimal paging signals transmission.

　　Certain embodiments provide a single channel resource for explicitly indicating the presence of a beam report which further implicitly indicates a sub-channel index for the reception and decoding of the beam report's first transmission.

　　Some embodiments provide a multi-channel structure in a grant free resource pool for reliable beam report transmission in multi user environment.

　　Other embodiments provide a variety of beam report formats and associated coding structure for use.

　　Some embodiments provided methods of transmitting instantaneous beam sweeping on SSBs to allow NR-UE to reduce the time staying awake in acquiring time/frequency synchronisation in the case that sparse SS burst set periodicity is configured. The SSBs in an instantaneous beam sweeping may also include compact paging message for system information updates.

　　Certain embodiments provide a framework for future implementation of hierarchy mobility management and UE tracking where some tracking functions can be handled at RAN level to reduce radio signal overhead.

　　Advantageously, embodiments of the invention may provide a low radio overhead paging procedure in multi-beams operational environment with a fallback option to full beam sweeping on LTE based paging procedure for progressive implementation and deployment (e.g. from low frequency band to high frequency bands where upto 64 SS-block beams are required), with regular beam reports upon wakeups. Furthermore, gNBs are be able to locate the location of a NR-UE within its coverage and therefore, paging signals can be transmitted at certain gNB, from selected TRP and even on selected beams.

　　Certain embodiments also provide framework for future design and implementation on hierarchy mobility management and UE tracking where some tracking functions can be handled at RAN level within overlapping groups of gNBs.

　　The introduction of instantaneous signals transmission as reference signal for time/frequency acquisition and beam measurement such as SSBs, as outlined in some embodiments, allows the gNB to reconfigure SS burst set periodicity without impacting NR-UE paging performance and power consumption.

　　Finally, the existence of a configured resource pool for limited or full beam reporting is implicitly indicated through the existence of a NR-PF or NR-PO and therefore the resource can be utilised for other purpose if there is no potential NR-PF.

　　In the present specification and claims (if any), the word 'comprising' and its derivatives including 'comprises' and 'comprise' include each of the stated integers but does not exclude the inclusion of one or more further integers.

　　Reference throughout this specification to 'one embodiment' or 'an embodiment' means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases 'in one embodiment' or 'in an embodiment' in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.

　　In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims (if any) appropriately interpreted by those skilled in the art.

　　This application is based upon and claims the benefit of priority from Australian provisional patent application No. 2017903970, filed on October 2, 2017, the disclosure of which is incorporated herein in its entirety by reference.

10　　paging message structure
11　　LTE paging structure
12　　5G or NR technology
13, 14, 15　　beam
16　　beam sweeping
50　　paging structure
60, 70　　radio frame
71　　beam reporting
110　　gNB
150　　NR-UE
200　　resource pool structure
210　　a single NR-PO
220　　multiple NR-POs
212, 222, 270　　resource pool
230　　resource structure
250　　resource pool structure
300　　coding structure
400　　resource structure
451, 452, 453　　beam reports

Claims

　　A method for use in a NR system comprising a plurality of gNBs and a plurality of NR-UEs, the NR-UEs configured to periodically wake up to monitor paging signals from the gNBs, the method comprising:
　　allocating, at a gNB of the plurality of gNBs, a resource pool which is associated with a NR paging frame for beam reporting from an intended NR-UEs or intended group of NR-UEs;
　　monitoring, at the gNB, the configured resource pool for one or more beam reports from one or more NR-UEs; and
　　transmitting, from the gNB and according to the one or more beam reports, beam-formed paging signals which are directed to one or more in coverage NR-UEs.
　　The method of claim 1, further comprising determining, at the gNB, a number of beams and a configuration of the beams to be serviced at TRPs of the gNB to achieve a desired coverage.
　　The method of claim 1, further comprising, providing, by the gNB and to one or more in-coverage NR-UEs of the plurality of NR-UEs, a synchronization signal block (SSB), for time and frequency acquisition and beam measurement.
　　The method of claim 3, wherein an NR-UE is configured to, upon waking, perform time and frequency acquisition and beam measurement base on the SSB.
　　The method of claim 1, wherein the reports may comprise limited beam reports or full beam reports.
　　The method of claim 1, wherein an NR-UE is configured to perform contention for one or more channels in transmitting the beam report.
　　The method of claim 1, wherein the resource pool is associated with a NR-PF, and the NR-PF comprises one or more NR-POs, and an NR-UE is configured to transmit the beam report in the resource pool corresponding to an NR-PO of the one or more NR-POs.
　　The method of claim 7, wherein the resource pools is configured in radio frames prior to each associated NR-PF.
　　The method of claim 1, wherein the gNB is configured to perform beam sweeping on instantaneous SSBs in response to receiving a paging initialisation from a Mobility Management Entity (MME).
　　The method of claim 9, wherein the gNB is further configured to allocate an instantaneous resource pool for beam reporting from the NR-UE, in a radio frame prior to an intended NR-PF in response to receiving the paging initialisation.
　　The method of claim 1, wherein the resource pool is associated with a NR-PF, and the start of the resource pool is defined with reference to the associated NR-PF.
　　The method of claim 1, wherein the start of the resource pool is defined with reference to the associated NR-PF by a predefined interval, which is less than or equal to 4ms.
　　The method of claim 1, where the resource pool for beam reporting may be configured to comprise:
　　a first part, for indicating preferred beam indexes in limited beam reporting;
　　a second part for transmitting a full beam report; or
　　a first part, for explicitly indicating the presence of a transmitting beam report followed by associated second part for transmitting the beam report in full beam reporting.
　　The method of claim 13, wherein the first part comprises is a single channel resource structure being semi-statically configured, by the gNB, to span at most one slot in time and a plurality of physical resource blocks (PRBs) in frequency, and is for transmitting preamble-like signatures from a plurality of NR-UEs that monitor a common NR-PF or one or more common NR-POs within a common NR-PF.
　　The method of claim 1, wherein limited beam reporting is configured, and beam indexes are mapped to predefined preamble-like signature indexes in the beam report.
　　The method of claim 1, wherein the resource pool for full beam reporting comprises an indexed multi-sub-channel structure being semi-statically configured to span over at least one single slot of 14-symbols in time, and over plurality of resource blocks (RBs) in frequency, and to be used with a set of predefined DMRS sequences.
　　The method of claim 16, wherein sub-channels of the sub-channel structure are indexed repeatedly, enabling a predefined number of retransmissions of a beam report.
　　The method of claim 16, wherein an association between a sub-channel DMRS index and a preamble-like signature is predefined.
　　The method according to claim 1, wherein the resource pool is associated with a NR-PF, and the NR-PF comprises one or more NR-POs, and the NR-POs comprise a burst of paging slots spanning over an NR-PO interval which is defined for full beam sweeping on a paging message.
　　The method according to claim 1, where a gNB is configured to determine a radio frame as a NR-PF based on the likelihood that at least one NR-UE in its coverage will monitor one or more NR-POs in that radio frame for intended paging signals upon waking-up.
　　The method of claim 20, where the gNB is configured to determine a likelihood of the NR-UE being in its coverage according to a shared NR-UE tracking database, which includes NR-UE information at initial network attachment and through periodic beam reporting.
　　The method of claim 21, wherein, upon determining that the NR-UE is likely within its coverage but that servicing TRPs of the NR-UE are not known, full beam sweeping is performed on paging signals on one or multiple NR-POs of the intended NR-PF from all associated TRPs.
　　The method according to claim 21, wherein, upon determining that the NR-UE is likely within its coverage and that the servicing TRPs of the NR-UE are known, full beam sweeping is performed on paging signals on one or multiple NR-POs of the intended NR-PF from only the servicing TRPs.
　　The method according to claim 21, wherein, upon determining that the NR-UE is likely within its coverage, that the servicing TRPs of the NR-UE are known, and the beam reference of the NR-UE is up-to-date, partial beam sweeping is performed on paging signals on one or multiple NR-POs of the intended NR-PF from only selected TRPs and on selected beams.
　　The method according to claim 1, wherein the gNB is configured to:
　　determine that a paged NR-UE is not likely within its coverage; and
　　not perform beam sweeping on paging signals on NR-POs of the intended NR-PF of the paged NR-UE to minimise radio signals overhead and to conserve the transmit power.
　　The method of claim 1, where the NR-UE contends for sub-channels on the resource pool for a beam report transmission by randomly selecting a sub-channel index.
　　The method of claim 26, wherein the NR-UE randomly select a DRMS index from a configured set in generating a first DMRS sequence for use in the first selected sub-channel.
　　The method of claim 27, wherein the NR-UE uses the selected sub-channel index and DMRS index for a first transmission of the beam report to derive the signature index indicating the presence of a beam report transmission basing on predefined associations.
　　The method according to claim 27, wherein in another sub-channel corresponding to the selected index, the NR-UE randomly select another DRMS index from the same configured set to generate a second DMRS sequence for use in the subsequent retransmissions.
　　The method according to claim 1, where a NR-UE may be configured by its servicing gNB to use a compact format, a normal format, or an extended format for a full beam report.
　　The method of claim 30, wherein the compact format comprises only a primarily preferred beam index or indexes.
　　The method of claim 31, where an NR-UE ID specific masking CRC is used with the compact format to identify a transmitter of the beam report.
　　The method of claim 30, where the normal beam report format comprises a primarily preferred beam index or indexes and an explicit NR-UE identifier.
　　The method according to claim 30, wherein the extended beam report format comprises primarily and secondarily preferred beam indexes, and an explicit NR-UE identifier.
　　The method according to claim 1, where a CRC-attached, channel-encoded and rate-matched beam report is masked with the assigned paging group identity, to enable interference randomisation to NR-UEs of different paging groups which may share the same grant-free resource pool in transmitting beam reports.