COMMUNICATIONS DEVICE AND METHODS PERFORMED THEREFOR - Patent application

Abstract

A method and a communication device for deriving cell quality based on multiple beams and a method performed by the communication device are provided. [Solution] In a communication device, a method for deriving cell quality includes measuring the beam quality of each of a plurality of beams of a cell (S410), identifying M beams corresponding to beam qualities within a range defined by the best beam quality value among the beam qualities of each of the plurality of beams and a predetermined beam quality value (S418), and deriving the cell quality by a linear average value of the beam qualities corresponding to the M beams (S420).

Description

[Technical field]

[0001] The present invention relates to communication systems. The present invention is particularly, but not exclusively, related to wireless communication systems and devices thereof operating in accordance with the 3GPP (3rd Generation Partnership Project) standard or equivalents or derivatives thereof. The present invention is particularly, but not exclusively, related to measuring cell quality in so-called 'next generation' systems using beamforming. [Background technology]

[0002] The latest development in the 3GPP standard is called LTE (Long Term Evolution) with EPC (Evolved Packet Core) network and E-UTRAN (Evolved UMTS Terrestrial Radio Access Network), also commonly referred to as '4G'. In addition, the terms '5G' and 'NR (new radio)' refer to evolved communication technologies that are expected to support a variety of applications and services. Various details of 5G networks are described, for example, in the 'NGMN 5G White Paper' V1.0 by the NGMN (Next Generation Mobile Networks) Alliance, which documents: https: / / www.ngmn.org / 5g-white-paper.html 3GPP plans to support 5G through its so-called 3GPP Next Generation (NextGen) Radio Access Network (RAN), and the 3GPP NextGen Core Network.

[0003] Under 3GPP standards, a NodeB (or eNB in ​​LTE, gNB in ​​5G) is a base station through which communication devices (user equipment or UE) connect to a core network and communicate with other communication devices or remote servers. For simplicity, this disclosure uses the term base station to refer to any such base station and the term mobile device or UE to refer to any such communication device. The core network (i.e., EPC in the case of LTE) hosts functions for subscriber management, mobility management, charging, security, and cell / session management, among other things, and provides communication devices with connectivity to external networks, such as the Internet.

[0004] The communication device may be, for example, a mobile communication device such as a mobile phone, a smartphone, a user equipment, a personal digital assistant, a laptop / tablet computer, a web browser, and / or an e-book reader. Such mobile (or even generally fixed) devices are typically operated by a user, although so-called Internet of Things (IoT) devices, and similar machine-type communication (MTC) devices, may also be network connected. For simplicity, the present disclosure refers to a mobile device (or UE) in the specification, but it is understood that the described techniques may be implemented in any communication device (mobile, and / or generally fixed) that can connect to a communication network to transmit and receive data, regardless of whether the communication device is controlled by human input or by software instructions stored in a memory.

[0005] 3GPP Technical Report (TR) 23.799 V0.7.0 describes possible architectures and general procedures for NextGen (5G) systems planned for Release 14 of the 3GPP standards. 3GPP is also considering the potential use of frequency bands up to 100 GHz for the new (5G) radio access network. Directional beamforming and large-scale antenna techniques may also be used to overcome the severe channel attenuation characteristics associated with certain high frequency bands (e.g. mmWave bands). The term 'large-scale antenna' refers to an antenna having a large number of antenna elements (e.g. 100 or more) arranged in an array. Indeed, such large-scale antennas may be used to communicate with several users simultaneously, thus facilitating multi-user multiple-input and multiple-output (MIMO) communications. A base station (also called transmission and reception point (TRP) in this case) may be configured to form respective beams for communicating with multiple UEs simultaneously using associated directional beams.

[0006] Beamforming is used in NR for the transmission of cell-specific channels, such as reference signals (RS) and system information. For a multiple beam cell, the number of beams and the beam pattern in the cell can be defined by a beam configuration. Thus, different cells have different beam configurations depending on the coverage requirements of each cell. To distinguish cell beams, each beam has a unique identifier (e.g., beam ID) in that cell.

[0007] To enable cell-level mobility, Radio Resource Management (RRM) measurements need to be performed by an actively connected UE to derive a measurement of cell quality for a particular cell. Such RRM measurements for cell-level mobility need to be performed based on a common framework, regardless of the network beam configuration (e.g. number of beams) and the UE beam configuration in a particular cell.

[0008] However, current proposals for obtaining cell quality measurements, and in particular for selecting the beam on which the cell quality should be based, are not ideal and are likely to lead to inconsistent measurements that do not accurately reflect the actual quality of the cell. Such inconsistent and potentially inaccurate measurements are undesirable as they may increase the risk of measurement report triggers, ping-pong handovers, and / or other undesirable consequences.

[0009] Thus, there is a need for improved methods for selecting beams for derivation of cell-level quality, deriving cell quality, and / or reporting cell-level quality and / or other beam related measurements. Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention seeks to provide an apparatus, and associated methods, that at least partially meets one or more of the above needs.

[0011] The inventors have considered several options for cell quality derivation based on single beam and multiple beams and realized that many of them are not ideal. For example, the inventors have considered the 1 best beam option, the N best beam option, the all detected beams option, and the above threshold beam option.

[0012] However, all these options for selecting beams for measurement have been found to have drawbacks and therefore do not provide an accurate indication of cell level quality.

[0013] In the best beam option, the cell quality measurement for a particular cell is based on the quality of the best (highest quality) beam in that cell. However, although this may sometimes provide a good indication of cell quality, due to channel variations, especially at higher frequencies, the UE may find that the best beam changes frequently. This may result in fluctuations in the derived cell quality, triggering measurement reports and increasing the risk of ping-pong handovers.

[0014] In the N best beams option, the cell quality measurement for a particular cell is based on the quality of the selection of the N best beams in that cell. While this addresses some of the issues of the best beams option, the selection of the N best beams does not guarantee that all selected beams are of similarly good quality. For example, in the case of N best beams with different beam qualities, combining (e.g. averaging) the quality measurements of those N beams may result in an underestimation of the cell quality. Furthermore, setting an appropriate value for N is complex.

[0015] For all detected beam options, the cell quality measurement for a particular cell is based on the respective quality of all beams in that cell. In this case, however, the UE may derive the cell quality based on a mix of good and bad quality beams. As a result, combining all beams may lead to a significant underestimation of the actual cell quality.

[0016] In the above threshold beam option, the cell quality measurement for a particular cell is based on the quality of the selection of the beam that shows a measurement quality above a given threshold for that cell. In this case, however, providing a good indication of cell quality depends on a proper setting of the threshold, which is not straightforward. For example, a higher threshold may be appropriate for UEs closer to the center of the cell than for UEs at the edge of the cell.

[0017] To at least partially alleviate one or more of the above problems, the inventors have proposed several alternatives / variations to the above options that attempt to provide at least some benefit to one or more of the above options. [Means for solving the problem]

[0018] In one aspect of the present invention, a method is provided that is performed by a communications device, the method including: a) measuring a respective beam quality for each of a plurality of beams of a cell; b) identifying a first group of beams from the plurality of beams, the first group having N beams, each of the beams in the first group exhibiting a respective measured beam quality that is the N best measured beam qualities resulting from the measurements; c) selecting from the first group of beams a second group of beams having M beams having a measured beam quality that is equal to or greater than a beam quality that is lower by a preset offset from the best measured beam quality; and d) deriving a cell quality of the cell based on the measured beam qualities of the M beams of the second group.

[0019] In one aspect of the invention, a method is provided for a communications device, the method comprising: a) measuring, at a serving cell of the communications device, a respective beam quality for each of a plurality of beams of the serving cell; b) identifying a group of serving cell beams having N beams among the plurality of beams of the serving cell, where each beam of the group of serving cell beams exhibits a measured beam quality among the N best measured beam qualities resulting from the measurements in a first cell, and the group of serving cell beams has a best serving cell beam exhibiting the best measured beam quality in the group of serving cell beams; c) measuring, at a neighboring cell of the serving cell, a respective beam quality for each of a plurality of beams of the neighboring cell; d) identifying a group of neighboring cell beams having N beams among the plurality of beams of the neighboring cell; a first beam of the group of neighbor cell beams having a first beam quality that is greater than or equal to N best measured beam qualities resulting from measurements of neighbor cells, and the group of neighbor cell beams has a best neighbor cell beam that exhibits the best measured quality in the group of neighbor cell beams; e) comparing the measured quality of the best serving cell beam with the measured quality of the best neighbor cell beam and identifying the lowest measured quality between the best serving cell beam and the best neighbor cell beam; f) selecting from the group of neighbor cell beams a further group of neighbor cell beams having M beams whose measured beam quality is greater than or equal to a quality that is lower than the identified lowest measured quality by a predetermined offset; and g) deriving the measured quality of the neighbor cell based on the measured beam qualities of the M beams of the further group of neighbor cell beams.

[0020] In one aspect of the invention, a method performed by a communications device includes: a) measuring, at a first cell, a respective beam quality for each of a plurality of beams of the first cell; b) identifying a first cell beam group having N beams among the plurality of beams of the first cell, each of the beams of the first cell beam group exhibiting a respective measured beam quality that is the N best measured beam qualities resulting from measurements at the first cell; c) measuring, at at least one second cell, a respective beam quality for each of the plurality of beams of the at least one second cell; and d) identifying at least one second cell beam group having N beams among the plurality of beams of the at least one second cell, each of the beams of the at least one second cell beam group exhibiting a respective measured beam quality that is the N best measured beam qualities resulting from measurements at the at least one second cell. a) identifying a group of second cell beams exhibiting respective measured beam qualities that are the N best measured beam qualities resulting from measurements at the at least one second cell; e) selecting from the group of first cell beams and the at least one group of second cell beams a further group of beams having M beams, each beam of the further group exhibiting a respective measured beam quality that is the M best measured beam qualities resulting from measurements at the first cell and the at least one second cell; f) deriving a cell quality of the first cell based on the measured beam qualities of the beams of the first cell in the further group; and g) deriving a cell quality of the at least one second cell based on the measured beam qualities of the beams of the at least one second cell in the further group.

[0021] In one aspect of the present invention, there is provided a method performed by a base station, the method comprising: a) sending a message to at least one UE to configure the at least one UE to perform cell quality measurements in at least one cell to which a plurality of beams are provided; and b) receiving from the UE a measurement report having at least one cell quality for the at least one cell derived based on measurements of beam quality for at least the selection of the beam using the method of any of the above aspects.

[0022] In one aspect of the present invention, a communications device is provided having a controller and a transceiver, wherein the controller is operable to: a) measure a respective beam quality for each of a plurality of beams of a cell; b) identify a first group of beams from the plurality of beams, the first group having N beams, each of the beams in the first group exhibiting a respective measured beam quality that is the N best measured beam qualities resulting from the measurements; c) select from the first group of beams a second group of beams having M beams having a measured beam quality that is equal to or greater than a beam quality that is lower by a preset offset from the best measured beam quality; and d) derive a cell quality of the cell based on the measured beam qualities of the M beams of the second group.

[0023] In one aspect of the present invention, a communication device includes a controller and a transceiver, the controller: a) measures, in a serving cell of the communication device, a respective beam quality for each of a plurality of beams of the serving cell; b) identifies a group of serving cell beams having N beams from the plurality of beams of the serving cell, where each beam of the group of serving cell beams exhibits a measured beam quality that is among the N best measured beam qualities resulting from the measurement in a first cell, and the group of serving cell beams has a best serving cell beam exhibiting the best measured beam quality in the group of serving cell beams; c) measures, in a neighboring cell of the serving cell, a respective beam quality for each of a plurality of beams of the neighboring cell; and d) identifies a group of neighboring cell beams having N beams from the plurality of beams of the neighboring cell; Here, a communications device is provided that is operable to: e) compare the measurement quality of the best serving cell beam with the measurement quality of the best neighboring cell beam and identify the lowest measurement quality between the best serving cell beam and the best neighboring cell beam; f) select from the group of neighboring cell beams a further group of neighboring cell beams having M beams whose measured beam quality is equal to or greater than a quality lower than the determined lowest measurement quality by a predetermined offset; and g) derive the measurement quality of the neighboring cell based on the measured beam qualities of the M beams of the further group of neighboring cell beams.

[0024] In one aspect of the invention, a system includes a controller and a transceiver, the controller comprising: a) measuring, at a first cell, a respective beam quality for each of a plurality of beams of the first cell; b) identifying, among the plurality of beams of the first cell, a group of first cell beams having N beams, each of the beams of the group of first cell beams exhibiting a respective measured beam quality that is the N best measured beam quality resulting from measurements at the first cell; c) measuring, at at least one second cell, a respective beam quality for each of the plurality of beams of the second cell; and d) measuring, among the plurality of beams of the at least one second cell, a group of at least one second cell beam having N beams, each of the beams of the group of at least one second cell beam exhibiting a respective measured beam quality that is the N best measured beam quality resulting from measurements at the at least one second cell. A communications device is provided that is operable to: e) identify a group of second cell beams exhibiting respective measured beam qualities that are the N best measured beam qualities resulting from measurements in at least one second cell; e) select from the group of first cell beams and the at least one group of second cell beams a further group of beams having M beams, each beam of the further group exhibiting a respective measured beam quality that is the M best measured beam qualities resulting from measurements in the first cell and the at least one second cell; f) derive a cell quality of the first cell based on the measured beam qualities of the beams of the first cell in the further group; and g) derive a cell quality of the at least one second cell based on the measured beam qualities of the beams of the at least one second cell in the further group.

[0025] In one aspect of the present invention, a base station has a controller and a transceiver, wherein the controller is operable to control the transceiver to: a) send a message to at least one UE to configure the at least one UE to perform cell quality measurements in at least one cell to which multiple beams are provided; and b) receive from the UE a measurement report having at least one cell quality for the at least one cell derived based on measurements of beam quality for at least the selection of the beam using the method described above.

[0026] In one aspect of the invention, there is provided a communication system comprising at least one base station as described above operating at least one cell and a communication device as described above.

[0027] Aspects of the invention extend to a computer program product, such as a computer program readable storage medium having stored thereon instructions operable to program a programmable processor to perform the methods according to the aspects and possibilities described above or recited in the claims, and / or instructions operable to program a computer suitably adapted to provide an apparatus as claimed in any of the claims.

[0028] Each feature disclosed in this specification (which term includes the claims) and / or shown in the drawings may be incorporated in the present invention independently (or in combination) with other disclosed and / or shown features. In particular, but not limited to, the features of a claim dependent on a particular independent claim may be introduced into that independent claim in any combination or individually.

[0029] Although particular hardware devices having particular physical structures (e.g., controller and transceiver circuitry) have been disclosed for performing the various procedures described herein, each step of the methods disclosed herein and / or forming part of the claims may be implemented by any suitable means for performing that step. Accordingly, each method aspect of the present invention has a corresponding apparatus aspect including respective means for performing each step of that method aspect. [Brief description of the drawings]

[0030] Example embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0031] [Figure 1] FIG. 1 shows a schematic diagram of a communication network. [Diagram 2] FIG. 2 is a block diagram showing the main components of user equipment for the communications network shown in FIG. [Diagram 3] FIG. 3 is a block diagram showing the main components of a base station for the communications network shown in FIG. [Figure 4] FIG. 4 is a flow diagram showing a method for deriving cell quality. [Diagram 5] FIG. 5 shows an example of beam selection according to the method of FIG. [Figure 6] FIG. 6 is a flow diagram showing another method for deriving cell quality. [Figure 7] FIG. 7 shows an example of beam selection according to a variation of the method of FIG. [Figure 8] FIG. 8 is a flow diagram showing another method for deriving cell quality. [Figure 9] FIG. 9 shows an example of beam selection according to the method of FIG. [Figure 10] Figure 10 is a simplified sequence diagram showing the measurement configuration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] overview Figure 1 illustrates diagrammatically a communications network 1 in which user equipment 3-1 to 3-4 (mobile handsets and / or other mobile devices) can communicate with each other via base stations 5-1 to 5-4 (denoted 'gNB') using an appropriate radio access technology (RAT). In a 5G system, base stations are also referred to as transmit receive points (TRPs). As those skilled in the art will appreciate, although four UEs 3 and four base stations 5 are shown in Figure 1 for illustrative purposes, the system, when implemented, will typically include other base stations and mobile devices.

[0033] Each base station 5 operates one or more associated cells via a TRP located at the base station (and / or one or more remotely located TRPs). In this example, for simplicity, each base station 5-1 to 5-4 operates a single cell 10-1 to 10-4, respectively. The base stations 5 are connected to the core network 7 (e.g., via appropriate gateways and / or user plane / control functions) and neighbouring base stations are also connected to each other (directly or via appropriate base station gateways). The core network 7 may include, among other things, a control plane manager entity, and a user plane manager entity, one or more gateways (GWs) that provide connectivity between the base stations 5 and other networks (such as the Internet) and / or servers hosted outside the core network.

[0034] The UE 3 connects to an appropriate cell (depending on its location and possibly other factors such as e.g. signal conditions, subscription data and / or reception capabilities) by establishing a radio resource control (RRC) connection with the base station 5 serving that cell. The UE 3 and the base station 5 (and other transmission points in the network) communicate over an appropriate air interface depending on the RAT used. The UE 3 communicates with the core network nodes using so-called Non-Access-Stratum (NAS) signaling, which is relayed between the UE 3 and the appropriate core network node by the base station 5 / TRP serving the UE 3.

[0035] In this example, each base station 5 operates an associated antenna array (e.g. a large antenna) to provide a number of directional beams for communicating with various UEs within the cell of each base station 5. Each beam is arranged to spread (transmit) in a different direction (in three dimensions including elevation (azimuth)). Each beam has an associated identifier (e.g. an appropriate 'beam ID') that is unique (at least within that cell). Although Figure 1 only shows a selection of beams provided by a single base station 5-1 for reasons of clarity, in reality each base station 5 will provide its own beams forming one or more associated cells.

[0036] The beam configuration used in a cell defines the number of beams and the associated beam pattern.

[0037] Each UE 3 is configured to derive a cell quality level measurement for each cell 10 that it can measure based on the selection of a beam from that cell 10 .

[0038] Advantageously, the beam used to derive the cell quality level for a particular cell is selected from an initial group of best beams for that cell (which may include a single best beam) based on a quality measurement of the best beam (e.g., reference signal received power (RSRP)) in that cell 10 or other cells 10.

[0039] In one example, the beam used to derive the cell quality level for a particular cell is selected from an initial group of best (highest measured quality) beams for that cell (which may have a single best beam) based on whether the quality measurement is in a range having an upper limit equal to the quality measurement for the best beam in that cell 10 and a lower limit equal to a quality that is lower by a pre-set offset from the quality measurement for the best beam in that cell 10.

[0040] In one example, the quality level derivation for a particular cell 10 advantageously takes into account the correlation between different beams within that cell 10 .

[0041] In another example, for a particular neighboring or target cell 10, the UE 3 advantageously performs a comparison between the measured quality of the best beam in the serving cell 10 and the measured quality of the best beam in the neighboring or target cell 10. The UE 3 identifies the beam with the lowest quality of the two compared beams. The UE 3 then sets the lower limit of the beam selection quality range to a quality that is lower by a pre-configured offset from the measured quality of the identified beam with the lowest quality. The beam used in the cell quality level derivation for a particular cell is selected from the initial group of best beams for that cell (which may have a single best beam) based on whether the quality measurement is above the lower limit.

[0042] In another example, the UE 3 aggregates the initial groups of beams from multiple measured cells and selects a group of best beams from all aggregated beams. The selected beams in this group of best beams may be beams that have a quality lower than the measured quality of the best beams by a preset offset. The cell quality level derivation for a particular cell is then performed based on the beams for that cell that are present in the group of best beams for multiple cells.

[0043] UE FIG. 2 is a block diagram illustrating the main components of user equipment 3 (eg, a mobile phone or other user equipment) shown in FIG.

[0044] As shown, the UE 3 has transceiver circuitry 31 operable to transmit signals to and receive signals from a base station 5 via one or more antennas 33. The UE 3 has a controller 37 which controls the operation of the UE 3. The controller 37 is associated with a memory 39 and coupled to the transceiver circuitry 31. Although not necessary for its operation, the UE 3 may of course have all the usual functionality of a normal mobile phone 3 (such as a user interface 35), which may be provided by one or a combination of hardware, software and firmware, as appropriate. Software may, for example, be installed in the memory 39 and / or downloaded over a communications network or from a removable data storage device (RMD).

[0045] The controller 37 is configured to control the overall operation of the UE 3, in this example by means of program or software instructions stored in memory 39. As shown, the software instructions include, among others, an operating system 41, a communication control module 43, a beam measurement module 44, a beam selection module 45, a filtering module 46, a cell quality derivation module 47, and a measurement reporting module 49.

[0046] The communications control module 43 is operable to control communications between the UE 3 and the serving base station 5 (as well as other communications devices connected to the base station 5, such as further UEs and / or core network nodes).

[0047] The beam measurement module 44 is responsible for detecting beams (in the serving cell and / or in the neighboring cells) and for performing quality measurements of the detected beams (e.g. Reference Signal Received Power (RSRP)). The beam selection module 45 is responsible for performing an initial selection of the best beam and a secondary selection from the group of initially selected beams to be used in the derivation of the cell quality measurements. The filtering module 46 is responsible for performing Layer 1 (L1) and Layer 3 (L3) type filtering. The cell quality derivation module 47 is responsible for the derivation of the cell quality for the selected beam. The measurement reporting module 49 is responsible for generating a measurement report including information related to the cell quality and for transmitting the measurement report to the base station 5.

[0048] base station FIG. 3 is a block diagram illustrating the main components of the base station 5 shown in FIG. 1. As shown, the base station 5 has a transceiver circuit 51 for transmitting signals to and receiving signals from communication devices (such as mobile phones 3 / user equipment) via one or more antennas 53 (e.g., array antennas / large-scale antennas), and a network interface 55 for transmitting signals to and receiving signals from network nodes (e.g., other base stations and / or nodes of the core network 7). The base station 5 has a controller 57 for controlling the operation of the base station 5. The controller 57 is associated with a memory 59. Software may, for example, be pre-installed in the memory 59 and / or downloaded via the communication network 1 or from a removable data storage device (RMD). The controller 57 is configured to control the overall operation of the base station 5 by program or software instructions stored in the memory 59, in this example. As shown, those software instructions include, among others, an operating system 61, a communication control module 63, a beam control module 64, and a measurement configuration module 66.

[0049] The communication control module 63 is operable to control communication between the base station 5 and the UE 3 and other network entities connected to the base station 5. The communication control module 63 controls the respective flows of downlink user traffic (via associated data radio bearers) and controls the control data transmitted to communication devices associated to this base station 5, including e.g. control data for core network services and mobility of the UE 3 (including also general (non-UE specific) system information and reference signals).

[0050] The beam control module 64 is responsible for managing the associated beam of each UE 3 within a cell (or multiple cells) of the base station 5. This includes, for example, adding and removing cells (e.g., based on signal measurements provided by the UE 3, the mobility of the UE 3, and / or other information related to the cell, such as load information).

[0051] The measurement configuration module 66 is responsible for configuring the UE 3 to perform and report cell quality measurements (and / or related information, e.g. correlation calculations) obtained based on beams (e.g. cells / beams operated by the base station 5 and / or neighboring base stations) in the vicinity of the UE 3. The measurement configuration module 66 obtains the cell quality measurements (and / or related information, e.g. correlation calculations) by generating and sending a measurement configuration appropriate for a particular mobile device 3 and receiving associated measurement reports. The measurement reports may be used, for example, when performing mobility and / or beam configuration procedures involving the UE 3 providing the report.

[0052] In the above, the mobile device 3 and the base station 5 have been described as having several separate modules (such as a communication control module and a beam configuration / control module) for ease of understanding. While in some applications these modules may be provided in this manner, for example when an existing system is modified to implement the present invention, in other applications, such as in a system designed from the beginning with the functionality of the present invention in mind, these modules may be incorporated into an overall operating system or code, and thus may not be recognizable as separate entities. These modules may also be implemented in software, hardware, firmware, or a combination thereof.

[0053] A more detailed explanation is given of some ways in which the cell quality can be derived (with reference to Figures 4-9).

[0054] Best beam selection for derivation of cell-level quality (A) Beam correlation is not taken into account in cell quality derivation (beam selection for each cell) FIG. 4 is a flow diagram illustrating, by way of example only, a method of cell quality derivation in which beam correlation is not taken into account.

[0055] As shown in FIG. 4, initially, for a particular cell 10, the UE 3 detects beams in that cell 10 in S410, and performs L1 filtering on the detected beams in S412.

[0056] At S414, the UE 3 selects N beams (N may be 1) for a particular cell 10 that are deemed to have the best quality (e.g., highest measured RSRP) from the beams detected in that cell 10. If the UE 3 detects N or more beams in the cell 10, the UE 3 may select only the N best beams. If the UE 3 detects N or fewer beams in the cell 10, the UE 3 may select all of the detected beams.

[0057] At S416, the UE 3 performs L3 filtering on the selected N best beams for the particular cell 10. At S418, the UE 3 selects M beams (M is not greater than N) from the selected N best beams that are within a set range between the measured RSRP of the best (highest quality) beam and a quality less a pre-set offset (in dB) than the measured RSRP of the best (highest quality) beam.

[0058] At S420, the UE derives a measure of cell quality by combining the RSRP measurements of the M selected beams having measurement qualities in a set range, which may be done in any suitable manner, for example based on an average, a weighted sum, and / or a maximum of the RSRP measurements of the M selected beams.

[0059] As indicated by the feedback loop of S422, UE3 repeats this procedure for each cell.

[0060] FIG. 5 follows the method of FIG. 4. bestbeam Indicates UE beam selection of M best beams (per cell) within the beam quality range with lower bound given by -offset.

[0061] Here, Q bestbeam is the beam quality measurement obtained from the best beam in the cell (e.g., maximum RSRP), and offset is Q bestbeam It is an amount in dB below (e.g. 1 dB, 2 dB).

[0062] In the example shown in FIG. 5, the number N of beams initially selected in each cell (cell #1 and cell #2) is N=3, and Q bestbeam The measurements are RSRP=5 dBm (in both cells) and offset=2 dB (in both cells). Therefore, the UE selects the best beam and up to M-1 beams that fall in the beam quality range between 5 dBm and 3 dBm and form part of the initially selected N beams.

[0063] In cell #1, the four beams are in the range of 5 dBm to 3 dBm (with RSRP=5 dBm, 4.5 dBm, 4 dBm, and 3 dBm, respectively), therefore, all three initially selected beams (with RSRP=5 dBm, 4.5 dBm, and 4 dBm) are selected as part of the M best beams (i.e., M=N=3). In cell #2, only the best beam is in the range of 5 dBm to 3 dBm (with RSRP=5 dBm), therefore, only one initially selected beam (with RSRP=5 dBm) is selected as the M best beam.

[0064] (B) Beam correlation is taken into account in cell quality derivation (beam selection per cell). FIG. 6 is a flow diagram illustrating, by way of example only, a method of cell quality derivation in which beam correlation is taken into account.

[0065] As shown in Figure 6, the method is similar to the method of Figure 4. Similar to the method described with reference to Figure 4, first, for a particular cell 10, the UE 3 detects beams in the cell 10 in S610, and performs L1 filtering on the detected beams in S612.

[0066] 4, UE 3 determines the degree of cross-correlation between the N selected beams and calculates a function of the correlation at S624. The correlation function may provide, for example, i) The number of beams that show low correlation among the N best beams ii) respective correlation coefficients for different pairs of the N best beams (e.g., [N×(N−1) / 2] coefficients); and / or iii) The difference in RSRP between the strongest beam (e.g., beam 1) and the strongest beam with low correlation with beam 1 (e.g., the minimum difference in RSRP between beam 1 and a beam (beam j) whose correlation with beam 1 is below a predefined correlation threshold, i.e., correlation(beam j, beam 1) < threshold, min{RSRP(beam 1) - RSRP(beam j)}).

[0067] The output of the above functions may be subject to L3 filtering at S626, if desired.

[0068] In parallel with the degree of cross-correlation, in S614, the UE 3 selects for a particular cell 10 N beams (N may be 1) that are deemed to have the best quality (e.g., highest measured RSRP) from the beams detected in that cell 10. If the UE 3 detects N or more beams in the cell 10, the UE 3 may select only the N best beams. If the UE 3 detects N or fewer beams in the cell 10, the UE 3 may select all of the detected beams.

[0069] At S616, the UE 3 performs L3 filtering on the selected N best beams for the particular cell 10. At S618, the UE 3 selects M (M not greater than N) beams from the selected N best beams whose measured RSRP is within a set range between the measured RSRP of the best (highest quality) beam and a quality less a pre-set offset (in dB) than the measured RSRP of the best (highest quality) beam.

[0070] At S620, the UE derives a measure of cell quality by combining the RSRP measurements of the M selected beams having RSRPs in the configured range, taking into account the output of the cross-correlation function calculation between the beams (possibly L3 filtered) at S624. This derivation may be performed in any suitable manner, for example based on an average, a weighted sum, and / or a maximum of the RSRP measurements of the M selected beams.

[0071] UE3 repeats this procedure for each cell, as indicated by the feedback loop at S622.

[0072] Figure 7 shows a UE beam selection according to a beneficial variation of the method shown in Figure 6. In this variation, the selection of a beam from the initial selection group of beams in a particular target cell 10, performed at S618, takes into account the quality of the best beam in the current cell serving the UE 3, providing a selection of a beam indicative of a better cell quality in each neighbouring cell, thus providing an improved cell quality measurement.

[0073] In particular, at S618, UE3 may compare the measured RSRPs of the best beams of a serving cell (e.g., cell 10-1) and a particular target neighboring cell (e.g., cell 10-2), and may use a range having a measurement-based lower limit that is lower than the lowest RSRP of the compared beams by a pre-configured offset (in dB) as a criterion for selecting the M best beams in that neighboring cell.

[0074] In this case, in addition to the best beam of a particular neighboring cell, UE3 includes in its selection from the N best beams other beams having measured RSRPs that are above a quality that is lower by a pre-set offset (in dB) than the lowest RSRP of the compared beams.

[0075] The lower limit of the selection range is expressed as follows: Minimum(Q bestbeam (Target), Q bestbeam(serving) - offset Here, Q bestbeam (target) is the beam quality measurement (e.g. maximum RSRP) obtained from the best beam in the neighboring ('target') cell, and Q bestbeam (serving) is the beam quality measurement (e.g. maximum RSRP) obtained from the best beam in the current ('serving') cell, and offset is Q bestbeam It is an amount in dB below (e.g. 1 dB, 2 dB).

[0076] In the example shown in FIG. 7, the initially selected number N in the serving cell (cell #1) and the target cell (cell #2) is N=3. bestbeam The measurement is RSRP=5dBm, and the Q bestbeam Measurement is 8dBm. Offset=2dB for both cells.

[0077] In the serving cell, the four beams are in the range of 5 dBm to 3 dBm (with RSRP=5 dBm, 4.5 dBm, 4 dBm, and 3 dBm, respectively), and therefore, all three initially selected beams (with RSRP=5 dBm, 4.5 dBm, and 4 dBm) are selected as part of the M best beams (i.e., M=N=3).

[0078] In the neighboring target cell, the beam with the best quality has a measured RSRP (8 dBm) that is greater than the RSRP (5 dBm) of the best beam in the serving cell. Therefore, the lower limit of the beam selection range is 3 dBm based on the serving cell's RSRP of 5 dBm. Therefore, in addition to the best quality beam in the neighboring target cell, two more beams (with RSRP = 4 dBm and 3.5 dBm) are selected for use in the cell quality derivation.

[0079] It can be seen in this example that the best quality beam of the neighbouring target cell was used as the criterion for determining the lower limit of the selection range, and only the best beam was selected (because the lower limit of the selection range was 6 dBm), which could have resulted in an unrealistically high measurement of cell quality.

[0080] It should be noted that although this variation has been discussed with reference to FIG. 6, this variation may be used in corresponding beam selection steps of other methods described herein.

[0081] (C) Beam correlation is taken into account in the cell quality derivation (selection of the best beam from all measured cells). FIG. 8 is a flow diagram illustrating, by way of example only, a method of cell quality derivation in which beam correlation is taken into account.

[0082] Similar to the method described with reference to FIG. 6, first, for a particular cell 10 (cells 1, 2, ... r), UE 3 detects a beam within that cell 10 in S810, and performs L1 filtering on the detected beam in S812.

[0083] For each cell 10, the UE 3 determines the degree of cross-correlation between the selected N beams and calculates a function of the correlation in S824. The correlation function may, for example, indicate the number of beams exhibiting low correlation among the N best beams of the target cell 10. The correlation function may, for example, provide: i) The number of beams that show low correlation among the N best beams ii) respective correlation coefficients for different pairs of the N best beams (e.g., [N×(N−1) / 2] coefficients); and / or iii) The difference in RSRP between the strongest beam (e.g., beam 1) and the strongest beam with low correlation with beam 1 (e.g., the minimum difference in RSRP between beam 1 and a beam (beam j) whose correlation with beam 1 is below a predefined correlation threshold, i.e., correlation(beam j, beam 1) < threshold, min{RSRP(beam 1) - RSRP(beam j)}).

[0084] The output of the above functions may be subject to L3 filtering in S826, if desired.

[0085] In parallel with the degree of cross-correlation, in S814, the UE 3 selects for each cell 10 N beams (N may be 1) that are deemed to have the best quality (e.g., highest measured RSRP) from the beams detected in that cell 10. If the UE 3 detects N or more beams in the cell 10, the UE 3 may select only the N best beams. If the UE 3 detects N or fewer beams in the cell 10, the UE 3 may select all of the detected beams.

[0086] At S816, the UE 3 performs L3 filtering on the selected N best beams for each cell 10.

[0087] Different from the methods described with reference to Figures 3 and 5, in S818, UE3 consolidates the RSRP results of all measured cells and selects M beams with the best measured RSRP. This may include all beams with measured RSRPs in a set range between the measured RSRP of the best quality beam in all cells and a pre-set offset (in dB) lower than the measured RSRP of the best quality beam in all cells. If a set offset is used, it may be different from the set offset value for the methods of Figures 3 and / or 5 (especially considering that the value of M for the method of Figure 8 may be larger than the value of M for the method of Figures 3 and / or 5).

[0088] If the M best beams in all measured cells do not include the best quality beam in the serving cell, the best quality beam from the serving cell is selected even though it does not belong to the M best beams. Best beams from certain neighboring cells are also included in the selection (if necessary) even though they are not in the M best beams.

[0089] At S820, UE3 derives for each cell (cell i) a measure of cell quality based on the quality measurements of the Mi beams selected in that cell (cell i) and taking into account the output (possibly L3 filtered) of the cross-correlation function calculation between the beams in S824 for that cell. This derivation may be performed in any suitable manner, for example based on the average, weighted sum, and / or maximum of the quality measurements of the M selected beams.

[0090] Therefore, when offsets are used in the method of FIG. 8, the beam selection in S818 is bestbeam (all) - it can be seen that we select the M best beams (among all detected beams in all measured cells) in a beam quality range with a lower limit given by offset, where Q bestbeam (all) is the beam quality measurement obtained from the best beam (e.g., the highest RSRP) among all beams detected in all measured cells, and the offset is Q bestbeam (All) is an amount in dB (e.g. 1 dB, 2 dB) below.

[0091] From this lower limit, Q bestbeam In addition to the selection of the M best beams in the selection range up to (all), the best quality beam of the serving cell is included in the selection even if it does not belong to the M best beams.

[0092] FIG. 9 illustrates UE beam selection according to the method of FIG. 8 in which no offset is used, but instead a predetermined number M of beams are selected at S818.

[0093] In the example shown in FIG. 9, there are only two cells, and the number of initially selected beams N in each cell (cell #1 and cell #2) is N=4 and M=6. bestbeam is RSRP=5 dBm, and the measured value Q bestbeam is RSRP=8dBm.

[0094] In cell #1, the N(4) initially selected beams are in the range of 5 dBm to 3 dBm (with RSRP=5 dBm, 4.5 dBm, 4 dBm, and 3 dBm, respectively). In cell #2, the N(4) initially selected beams are in the range of 8 dBm to 6 dBm (with RSRP=8 dBm, 7.5 dBm, 6.5 dBm, and 6 dBm, respectively). Therefore, the M(6) best beams selected from the combined set of 8 beams of both cells include all the 4 initially selected beams in cell #2 (i.e., M2=4) and the 2 initially selected best beams in cell #1 (i.e., M1=2).

[0095] UE3 then derives a measure of cell quality for cell #1 and cell #2 based on the respective quality measurements of the selected beam in each cell.

[0096] Calculating correlations between beams There are various ways in which the correlation between the beams can be measured in any of the corresponding methods above.

[0097] Two possible options for the calculation of the correlation between the beams are described by way of example only.

[0098] In a first option, the correlation between the two beams is estimated over a sufficiently long period and a sufficient number of jamming events to provide a sufficiently accurate measure of correlation, which can be done, for example, by calculating the Pearson coefficient between sequences of respective measurements (e.g. measured RSRP values, measured number of jammings detected) for each of the two beams.

[0099] In a second option, if the averaging period required for the first option is too long to measure the correlation directly, the correlation can be estimated from proxy measurements. For example, the correlation can be estimated from the propagation delay or other characteristics of each beam's respective power delay profile, based on the assumption that beams with widely differing propagation delays will have low correlation. The angle of arrival of each transmit beam can also be taken into account (especially if the UE receive beams for each beam are different).

[0100] Derivation of cell-level quality (general case) There are various ways in which the cell quality can be derived from the quality measurements of the selected beam (as for the methods described above).

[0101] In the general case, UE3 determines one or more parameters: the quality of the best beam selected in one cell (Qbeam1, Qbeam2, ..., Qbeam M ), the number of best beams selected in a cell (M), and / or a function of the correlation of beams in a cell (C). Thus, in general, the cell quality derivation is expressed as follows:

number

[0102] As examples, the function f() could be the average (or maximum or sum) of the beam quality (Qbeam) plus a correction term derived from M and C, or an estimate of the outage probability (the fraction of time that cell quality is below a given level) derived from an assumed probability distribution parameterized by Qbeam, M, and C.

[0103] With reference to the values ​​of M and C, it can be seen that the reliability of a cell tends to increase with the number of best beams in the beam quality selection range that can be selected in a cell (i.e., increases with M). Conversely, the cell reliability tends to decrease with increasing correlation between the M beams (i.e., decreases with increasing C). The value of C can be determined based on the correlation coefficients between all possible pairs of M beams (number of coefficients=M×(M−1) / 2). The value of C can be determined based on each of the correlation coefficients between the best beam and each of the other beams (number of coefficients=M−1). Note that the correlation functions described with reference to Figures 6 and 8 (e.g., options i), ii), and / or iii)) can also be applied.

[0104] Deriving cell-level quality (using weighted summation) In one example, the UE 3 can derive the cell quality based on a weighted sum (as per the method above).

[0105] In this example, UE3 sorts the selected M best beams based on their quality values ​​such that the quality of the beam with index=1 (Qbeam1) is the best beam quality, the beam with index=2 (Qbeam2) is the second best quality beam, etc. UE3 then calculates the cell quality by adding the weighted values ​​of the beam qualities across all M beams to provide a cell level quality measure as follows:

number

[0106] In general, it is preferable for a UE 3 to be served by the strongest beam in a particular cell. Therefore, in order to appropriately weight the contribution of each beam in the sum of the M beams, a large weight (W i ) is assigned to the strongest beam and smaller weights are assigned to weaker beams. For example, the weights can be set to

number

[0107] In a variant, the 'weight' applied to a particular beam depends on the correlation between that beam and the best quality beam, as follows:

number

[0108] Beneficially, the cell-level quality derived for neighbouring cells whose beams are highly correlated will therefore be lower than the cell-level quality derived for neighbouring cells whose beams are less correlated.

[0109] Report Beneficially, the derived cell quality measurements (in any of the above methods) may be provided using a measurement report having one or more measurement objects (cell level quality, number of selected best beams (M), and / or correlation coefficient for the M best beams).

[0110] The report may be explicit, for example if the UE 3 is able to include all measurement objects (cell level quality, number of selected best beams, and correlation coefficient) in the measurement report. In this case, the reported cell quality is reported using, for example, Qbeam i is the RSRP measurement, and the function of the M best beam measurements (CellQuality = f(Qbeam1,…,QbeamM ))

[0111] The report may be explicit, for example, where the UE simply includes a cell level quality object, where the cell quality level is calculated as a function of the M best beam measurements, the number of beams, and a correlation coefficient of the M best beams.

[0112] The report may, for example, be a hybrid of explicit and implicit reporting, in which case UE3 may include a cell level quality object (where the cell quality level is calculated as a function of the M best beam measurements and the M best beam correlation coefficients) and the number of the M best beam measurement objects.

[0113] These reporting options are now explained in more detail with reference to FIG. 10 which is a simplified sequence diagram showing, by way of example only, how cell quality level measurements may be configured for the purposes of a handover procedure.

[0114] As shown in Figure 10, the base station 5-1 (acting as a source base station in this example) configures, in S1010, one or more UEs 3 to assist in performing measurements of the serving cell 10-1 served by the base station 5-1 and any neighboring cells 10-2, 10-3, 10-4 that the UEs 3 can detect. In Figure 10, the base station 5-1 uses a "measconfig" information element IE to configure the measurements in the UEs 3, although any suitable message / IE could be used.

[0115] The base station 5-1 may, for example, include one or more measurement object IEs (e.g., in a measconfig IE) that contain configuration information appropriate for the measurements. This configuration may include, for example, one or more of a carrier frequency ("carrierFreq") identifying the carrier frequency for which this configuration is valid, an offset ("offsetFreq") defining an offset value applicable to the carrier frequency, a list of cells to remove from the neighbor cell list (e.g., cellsToRemoveList), a list of cells to add / modify in the neighbor cell list (e.g., cellsToAddModList), an individual offset for one or more cells in the list of cells to be added / modified (e.g., a cellIndividualOffset), one or more beam offsets to be applied when selecting the M best beams for a cell (e.g., in the manner described with reference to Figures 4, 6, and / or 8 above), and / or a number N of beams to be initially selected, etc.

[0116] Note that within the measurement configuration, the value of N and the offset value can be set per cell, per frequency, or as a general configuration per UE.

[0117] The base station 5-1 may, for example, include one or more report configuration IEs (e.g., reportconfig IEs) with configuration information for configuring one or more cell quality report trigger events, appropriate associated trigger thresholds, offsets, and / or hysteresis values ​​(e.g., in the measconfig IE). If the system allows different types of reports as described above, the base station 5-1 may, for example, include one or more report configuration IEs (e.g., in the measconfig IEs) with an indication of the type of reporting to be performed by the UE 3 (e.g., explicit, implicit, hybrid).

[0118] Each UE 3 performs beam quality measurements on the serving cell and neighboring cells in accordance with the measurement configuration information in S1012. The UE 3 derives cell-level quality in S1014 based on the measurements (e.g., using one of the techniques described above) before reporting the cell-level quality to the base station 5-1 in S1016.

[0119] Note that reports are typically event triggered based on configured report triggers (e.g., configured trigger thresholds, offsets, and / or hysteresis values). The UE 3 therefore checks the trigger conditions (based on the cell-level quality measurements and the configured report triggers, among other things) to determine whether a measurement report should be sent or not.

[0120] As mentioned above, the UE 3 may derive the cell-level quality based on a function of the measurements performed on the M best beams. The UE 3 may report the cell-level quality results to the base station 5-1 together with the number M of best beams, the correlation function results C calculated for all (or selected) possible beam pairs (e.g. as shown in S1016-1), and possibly other parameters (e.g. the correlation functions described with reference to Figures 6 and 8 above (e.g. options i), ii), and / or iii)).

[0121] The UE 3 may derive the cell-level quality based on the results of measurements performed on the M best beams, the number M of the best beams, and a function of the correlation function result C calculated for all (or selected) possible beam pairs. The UE 3 may report the cell-level quality results to the base station 5-1 (without separately including the number M of the best beams and the calculated correlation function result C) (as shown in S1016-2).

[0122] The UE 3 may derive the cell-level quality based on the results of measurements performed on the M best beams and a function of the correlation function result C calculated for all (or selected) possible beam pairs. The UE 3 may report the cell-level quality result to the base station 5-1 together with the number M of best beams (without separately including the calculated correlation function result C) (as shown in S1016-3).

[0123] In general, the cell-level quality derivation and reporting can be independent, i.e., even if M and C are used in the derivation of the cell quality (implicit case), M and C can be explicitly reported together with the cell quality derivation.

[0124] The source base station 5-1 decides to handover the UE 3 and determines a suitable handover target 5-2 based on the cell-level quality reported in the measurement report received from the UE 3 and related radio resource management information in S1018. The source base station 5-1 issues a handover request message to the identified target base station 5-2 in S1020, passing necessary information for preparing the handover at the target side.

[0125] The admission control may be performed by the target base station 5-2 before it prepares for the handover and sends a handover request confirmation to the source base station 5-1. The target base station 5-2 generates an RRC message (e.g. an RRCConnectionReconfiguration message) that triggers the execution of the handover and includes it in the handover request confirmation sent to the source base station 5-1 in S1022. Data transfer may start once the source base station 5-1 receives the handover request confirmation or starts sending a handover command in the downlink.

[0126] At S1024, the source base station 5-1 transmits an RRCConnectionReconfiguration message to the UE 3 to instruct the UE 3 to execute handover. The UE 3 receives the RRCConnectionReconfiguration message and necessary parameters, and is therefore instructed by the source base station 5-1 to execute handover.

[0127] The handover then proceeds to a handover execution phase at S1026 and a handover completion phase at S1028. Those skilled in the art are familiar with such procedures, and for reasons of pertinent matter will not be repeated.

[0128] Variations and substitutions Detailed exemplary embodiments have been described above. As those skilled in the art will appreciate, many variations and alterations may be made to the above exemplary embodiments while still benefiting from the invention embodied therein. For purposes of illustration only, some of these alterations and variations are described.

[0129] In the above description, RSRP was used as the beam quality measurement, but other parameters may be used instead (or in addition to RSRP), for example Reference Signal Received Quality (RSRQ), carrier Received Signal Strength Indicator (RSSI), Channel Quality Indicator (CQI), Signal to Interference plus Noise Ratio (SINR), and / or Signal to Noise Ratio (SNR) measurements may be used.

[0130] The offsets described above may be fixed or may be network configurable values, for example, the offsets may be configured as members of a predefined group of possible offsets.

number

[0131] The UE may have multiple beams, and for each base station transmitted beam, the UE may use a different receiving beam.

[0132] In the above exemplary embodiment, the base station communicates with the mobile device using 3GPP wireless communication (radio access) technology. However, any other wireless communication technology (i.e. WLAN, Wi-Fi, WiMAX, Bluetooth, etc.) can be used for communication between the base station 5 and the mobile device 3 according to the above exemplary embodiment. The above exemplary embodiment can also be applied to "non-mobile" or generally stationary user equipment.

[0133] For ease of understanding, the UE has been described above as having a number of separate functional components or modules. While these modules may be provided in this manner for a particular application, for example where an existing system is modified to implement the present invention, in other applications, for example in systems designed from the ground up with the features of the present invention in mind, the modules may be incorporated into the overall operating system or code and therefore may not be recognized as separate entities.

[0134] In the above description, the UE has been described as performing cell quality measurements. In a variant, the UE may measure the beam quality and provide the beam quality measurements to the base station. The base station may then derive the cell quality (e.g., as described above).

[0135] One example described herein includes a method implemented in a communications device, comprising: a) measuring beam qualities of each of a plurality of beams of a cell; b) identifying a first group of beams from the plurality of beams having N beams, where each beam of the first group exhibits a respective measured beam quality that is among the N best measured beam qualities resulting from the measurements; c) selecting a second group of beams from the first group having M beams whose measured beam qualities are equal to or greater than a predetermined offset lower than the best measured beam quality for the beams of the first group; and d) deriving a cell quality of the cell based on the measured beam qualities of the M beams of the second group.

[0136] The method may further comprise reporting the cell quality to the base station in a measurement report. The method may further comprise determining a correlation between at least one pair of beams of the first group and / or the second group. Information for identifying the correlation (or a value calculated based on the correlation) may be included in the measurement report separately from the derived cell quality. The cell quality may be further derived based on the determined correlation (or a value calculated based on the determined correlation). Information identifying a number M of beams in the second group may be included in the measurement report separately from the derived cell quality. The cell quality may be further derived based on the number M of beams in the second group.

[0137] The cell quality may be derived based on the following formula:

number

[0138] The cell quality may be derived based on the following formula:

number

[0139] The cell quality may be derived based on the following formula:

number

number

[0140] The method may include performing filtering (e.g., L3 filtering) on ​​the identified beams in the first group, and selecting a second group of beams from the first group of beams is performed based on the identified beams in the filtered first group.

[0141] The method may further comprise repeating steps a) to d) for at least one further cell.

[0142] One example described herein is a method performed by a communications device, comprising: a) measuring, at a serving cell of the communications device, a respective beam quality for each of a plurality of beams of the serving cell; b) identifying a group of serving cell beams having N beams among the plurality of beams of the serving cell, where each beam of the group of serving cell beams exhibits a measured beam quality among the N best measured beam qualities resulting from measurements in a first cell, and the group of serving cell beams has a best serving cell beam exhibiting the best measured beam quality in the group of serving cell beams; c) measuring, at a neighboring cell of the serving cell, a respective beam quality for each of the plurality of beams of the neighboring cell; d) identifying a group of serving cell beams having N beams among the plurality of beams of the neighboring cell. The method includes: identifying a loop, where each beam of the group of neighbor cell beams exhibits a measured beam quality that is among the N best measured beam qualities resulting from measurements of neighbor cells, and the group of neighbor cell beams has a best neighbor cell beam exhibiting the best measured quality in the group of neighbor cell beams; e) comparing the measured quality of the best serving cell beam with the measured quality of the best neighbor cell beam and identifying the lowest measured quality between the best serving cell beam and the best neighbor cell beam; f) selecting from the group of neighbor cell beams a further group of neighbor cell beams having M beams whose measured beam quality is equal to or greater than a quality that is lower than the determined lowest measured quality by a predetermined offset; and g) deriving the measured quality of the neighbor cell based on the measured beam qualities of the M beams of the further group of neighbor cell beams.

[0143] The method may further comprise repeating steps c) to g) for at least one further neighbouring cell of the serving cell.

[0144] One example described herein is a method performed by a communications device, comprising: a) measuring, at a first cell, a respective beam quality for each of a plurality of beams of the first cell; b) identifying, among the plurality of beams of the first cell, a group of first cell beams having N beams, each of the beams of the group of first cell beams exhibiting a respective measured beam quality that is the N best measured beam qualities resulting from the measurements at the first cell; c) measuring, at at least one second cell, a respective beam quality for each of a plurality of beams of the second cell; d) identifying, among the plurality of beams of the at least one second cell, a group of at least one second cell beam having N beams, each of the beams of the group of at least one second cell beam exhibiting a respective measured beam quality that is the N best measured beam qualities resulting from the measurements at the first cell; The method further comprises: e) identifying a group of second cell beams exhibiting respective measured beam qualities that are the N best measured beam qualities resulting from measurements in the at least one second cell; e) selecting from the group of first cell beams and the at least one group of second cell beams a further group of beams having M beams, each of the beams in the further group exhibiting respective measured beam qualities that are the M best measured beam qualities resulting from measurements in the first cell and the at least one second cell; f) deriving a cell quality of the first cell based on the measured beam qualities of the beams of the first cell in the further group; and g) deriving a cell quality of the at least one second cell based on the measured beam quality of the beam of the at least one second cell in the further group.

[0145] The first cell may include a serving cell, and the at least one second cell may be at least one neighbor cell.

[0146] One example described in this specification includes a method performed by a base station, the method including: a) sending a message to at least one UE to configure the at least one UE to perform cell quality measurements in at least one cell to which multiple beams are provided; and b) receiving from the UE a measurement report having at least one cell quality for the at least one cell derived based on measurements of beam quality for at least a selection of beams using the method described above.

[0147] The method may further include making a handover decision based on the at least one cell quality measurement. The decision may be further based on at least one of a value M representing a number of beams selected by the UE to be in the group, each beam of the group exhibiting a respective measured beam quality among the M best measured beam qualities, and a correlation value (or a value calculated based on the correlation values) between at least one pair of beams of the group. The value M and at least one of the correlation value (or a value calculated based on the correlation values) may be provided in a measurement report.

[0148] In the above exemplary embodiment, several software modules have been described. As those skilled in the art will appreciate, the software modules can be provided in compiled or uncompiled form and can be provided to the base station, the mobility management entity, or the mobile device as a signal over a computer network or a recording medium. Furthermore, the functionality performed by part or all of this software can be performed using one or more dedicated hardware circuits. However, the use of software modules is preferred because it facilitates the updating of the base station or the mobile device to update the functionality of the base station or the mobile device.

[0149] Each controller may have any suitable form of processing circuitry, including, but not limited to, one or more hardware-implemented computer processors, microprocessors, central processing units (CPUs), arithmetic logic units (ALUs), input / output (IO) circuitry, internal memory / cache (program and / or data), processing registers, communications buses (e.g., control buses, data buses, and / or address buses), direct memory access (DMA) capabilities, hardware or software implemented counters, pointers, and / or timers, etc.

[0150] Various other modifications will be apparent to those skilled in the art and will not be described in further detail here.

[0151] This application claims the benefit of priority to UK patent applications nos. 1701858.1 and 1702281.5, filed February 3, 2017 and February 10, 2017 respectively, the disclosures of which are incorporated herein by reference in their entireties.

Claims

1. 1. A method performed by a communications device, comprising: receiving measurement configuration information including information indicating a predetermined value and information indicating a predetermined number N of beams (N is an integer equal to or greater than 2) from a base station; measuring a beam quality of each of a plurality of beams of the cell; Identifying M beams (M is an integer equal to or greater than 2) corresponding to beam qualities between a best beam quality value among the beam qualities of each of the plurality of beams and a lower limit value determined based on the best beam quality value and the predetermined value, within a range not exceeding the predetermined number of beams N; determining a cell quality by a linear average of beam qualities corresponding to the M beams; method.

2. 1. A communications device, comprising: A means for receiving measurement configuration information including information indicating a predetermined value and information indicating a predetermined number N of beams (N is an integer equal to or greater than 2) from a base station; means for measuring beam quality of each of a plurality of beams of the cell; a means for identifying M beams (M being an integer of 2 or more) corresponding to a beam quality between a best beam quality value among the beam qualities of each of the plurality of beams and a lower limit value determined by the predetermined value, within a range not exceeding the predetermined number of beams N; and means for determining a cell quality by a linear average of beam qualities corresponding to the M beams.

Images