Collaborative operations for radio measurement reduction

Abstract

Various example embodiments relate to apparatuses and methods supporting collaborative operations for radio measurement reduction. An apparatus for a terminal device may be configured to perform: measuring a first set of beams to determine an index of at least one strongest beam for multiple time instances; storing first information on index transition of the at least one strongest beam over the time instances; reporting the first information to a network device; receiving, from the network device, second information on index transition of the at least one strongest beam over time, wherein the second information is based on the first information; and measuring a second set of beams based on the second information.

Description

COLLABORATIVE OPERATIONS FOR RADIO MEASUREMENT REDUCTIONTECHNICAL FIELD

[0001] Various example embodiments generally relate to wireless communications and, in particular, to apparatuses and methods supporting collaborative operations for radio measurement reduction.BACKGROUND

[0002] Certain abbreviations that may be found in the description and / or in the figures are herewith defined as follows:3 GPP Third Generation Partnership ProjectAl Artificial IntelligenceBM Beam ManagementBS Base StationML Machine LearningNR New RadioRAN Radio Access NetworkRRC Radio Resource ControlRSRP Reference Signal Received PowerRSRQ Reference Signal Received QualitySINR Signal to Interference plus Noise RatioUE User Equipment

[0003] 5GNew Radio (NR) networks introduce new challenges to mobility management due to tightened beamforming requirements. In a beamforming enabled architecture, a base station (BS) deploys a number of beams each covering a relatively small area, and mobile UE may frequently change serving beam to maintain a reliable connection with the base station. As a result, UE and network have to perform a significantly increased number of measurements for monitoring network conditions and performing network mobility management in a timely manner, including beam-level mobility (e.g., beam switching) and cell-level mobility (e.g., handover).SUMMARY

[0004] A brief summary of exemplary embodiments is provided below to provide basic understanding of some aspects of various embodiments. It should be noted that this summary is not intended to identify key features of essential elements or define scopes of the embodiments, and its sole purpose is to introduce some concepts in a simplified form as a preamble for a more detailed description provided below.

[0005] In a first aspect, an example embodiment of an apparatus for a terminal device is provided. The apparatus may comprise at least one processor and at least one memory. The at least one memory stores instructions that, when executed by the at least one processor, cause the apparatus to measure a first set of beams to determine an index of at least one strongest beam for multiple time instances and store first information on index transition of the at least one strongest beam over the time instances. The apparatus is further caused to report the first information to a network device and receive second information on index transition of the at least one strongest beam over time from the network device. The second information is based on the first information. The apparatus is further caused to measure a second set of beams based on the second information.

[0006] In a second aspect, an example embodiment of an apparatus for a network device is provided. The apparatus may comprise at least one processor and at least one memory. The at least one memory stores instructions that, when executed by the at least one processor, cause the apparatus to receive first information on index transition of at least one strongest beam over time from a plurality of terminal devices, combine the first information received from the plurality of terminal devices to obtain second information on index transition of the at least one strongest beam over time, and transmit the second information to one or more terminal devices.

[0007] In a third aspect, an example embodiment of an apparatus for a terminal device is provided. The apparatus may comprise at least one processor and at least one memory. The at least one memory stores instructions that, when executed by the at least one processor, cause the apparatus to measure a first set of cells to determine an index of at least one best cell for multiple time instances and store first information on index transition of the at least one best cell over the time instances. The apparatus is further caused to report the first information to a network device and receive second information on index transition of the at least one best cell over time from the network device. The second information is based on the first information. The apparatus is further caused to measure a second set of cells based on the second information.

[0008] In a fourth aspect, an example embodiment of an apparatus for a network device isprovided. The apparatus may comprise at least one processor and at least one memory. The at least one memory stores instructions that, when executed by the at least one processor, cause the apparatus to receive first information on index transition of at least one best cell over time from a plurality of terminal devices, combine the first information received from the plurality of terminal devices to obtain second information on index transition of the at least one best cell over time, and transmit the second information to one or more terminal devices.

[0009] Other aspects provide example embodiments of methods, apparatuses, computer readable media and computer programs supporting collaborative operations for radio measurement reduction, which generally correspond to the above aspects and a repetitive description thereof is omitted here for convenience.

[0010] Other features and advantages of the example embodiments of the present disclosure will also be apparent from the following description of specific embodiments when read in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of example embodiments of the present disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Some example embodiments will now be described, by way of non-limiting examples, with reference to the accompanying drawings.

[0012] Fig. 1 is a schematic diagram illustrating a wireless communication network in which example embodiments of the present disclosure can be practiced.

[0013] Fig. 2 is a schematic diagram illustrating an inference procedure by an artificial intelligence (Al) / machine learning (ML) model according to some example embodiments.

[0014] Fig. 3 is a signaling diagram illustrating an example process according to some example embodiments.

[0015] Fig. 4A is a schematic diagram illustrating an example sequence of beam / cell-level measurements according to some example embodiments.

[0016] Fig. 4B is a schematic diagram illustrating an example table indicating index transition of the best beam / cell according to some example embodiments.

[0017] Fig. 4C is a schematic diagram illustrating an example histogram in a form of matrix according to some example embodiments.

[0018] Fig. 4D is a diagram illustrating an example histogram according to some example embodiments.

[0019] Fig. 5 is a flowchart illustrating an example method according to some exampleembodiments.

[0020] Fig. 6 is a flowchart illustrating an example method according to some example embodiments.

[0021] Fig. 7 is a schematic block diagram illustrating example devices in a communication system according to some example embodiments.

[0022] Throughout the drawings, same or similar reference numbers indicate same or similar elements. A repetitive description on the same elements would be omitted.DETAILED DESCRIPTION

[0023] Herein below, some example embodiments are described in detail with reference to the accompanying drawings. The following description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known circuits, techniques and components are shown in block diagram form to avoid obscuring the described concepts and features.

[0024] Fig. 1 illustrates an example of a wireless communication network 100 in which example embodiments of the present disclosure may be practiced. The wireless communication network 100 may be for example a cellular communication network, which may include one or more base stations 120 that form a so-called radio access network (RAN) to provide access to the network for a plurality of UEs 110 (only two UEs 110a, 110b are shown). The RAN or base station(s) 120 is connected to a core network (CN) 130, which can provide secure and reliable access to network services and connectivity to external data networks e.g., Internet (not shown).

[0025] The UE 110, also known as terminal device, terminal equipment, mobile station or the like, is generally a device configured to communicate with a network device or other UEs in the communication network 100. The UE 110 may be a portable computer (e.g., laptop, notebook, tablet computer), mobile phone (e.g., cell phone, smartphone), wearable computer (e.g., smartwatch), or the like. In other examples, the UE 110 may be an Internet of things (loT) device, an industrial loT (IIoT device), a vehicle equipped with a vehicle-to-everything (V2X) communication technology, or the like. In some examples, as referenced by 3GPP, the UE 110 may be a narrowband loT (NB-IoT) device, an enhanced machine-type communication (eMTC) device, a reduced capability (RedCap) device, an ambient loT device, or the like.

[0026] In operation, the UE 110 may be configured to connect to one or more base stations120 according to their particular radio access technologies to thereby access the CN 130 of the wireless communication network 100. Examples of radio access technologies comprise 3GPP radio access technologies such as GSM, UMTS, LTE, LTE Advanced, 5G NR, 5G Advanced, 6G, and the like. Other examples of radio access technologies comprise IEEE 802 technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.15 (e.g., 802.15.1 (WPAN / Bluetooth), 802.15.4 (Zigbee) and 802.15.6 (WBAN)), Bluetooth, Bluetooth Low Energy (BLE), ultra wideband (UWB), and the like. Generally, a radio access technology may refer to any 2G, 3G, 4G, 5G, 6G or higher generation mobile communication technologies and their different versions, as well as to any other wireless radio access technologies that may be arranged to interwork with such mobile communication technologies to provide access to the CN 130 of a mobile network operator (MNO).

[0027] The base station 120, also known as base transceiver station, network device, network node, access node, access point or the like, may comprise any suitable entity(ies) or device(s) that can provide coverage or cells to interact with the UEs 110. In some examples, the base station 120 may be implemented as Node B (NB), Evolved NB (eNB), next generation Evolved NB (ng-eNB), next generation NB (gNB), enhanced gNB (en-gNB), or the like. In some examples, the base station 120 may consist of several distributed network units, such as a central unit (CU), one or more distributed units (DUs), and one or more remote radio heads (RRHs) or remote radio units (RRUs). The number and functions of these distributed units depend on the selected split RAN architecture.

[0028] The core network 130 may include numerous network functions (NFs) (not shown) to support various functionalities such as subscriber data management, authorization, authentication policy management, session management, mobility management, etc. In some examples, the core network 130 may be deployed on cloud, e.g. a public cloud, a private cloud or a hybrid cloud.

[0029] 5G NR has extended to millimeter wave (mm Wave) spectrum, also known as frequency range 2 (FR2), in order to provide an ultra-fast data rate, a very low latency and a significantly improved spectral efficiency. However, mmWave communication suffers from high path loss, which restricts the effective range of transmission. To tackle this problem, beamforming with large-scale antenna arrays can be utilized to generate finely directional beams. As shown in Fig. 1, the base station 120 may comprise one or more antenna panels, each including a number of dual-polarized antenna elements arrayed in columns and rows. The base station 120 can control amplitudes and phase shifts of transmit (Tx) signals provided to the antenna elements such that the Tx signals radiated from the antenna elements coherentlycombine together for a particular transmit direction and destructively cancel each other out for other directions, forming an aggregated signal beam with more power propagating in the particular direction.

[0030] In beamforming enabled networks, a base station can be configured to generate a number (e.g., up to 64) of beams, each covering a relatively small area of a cell. As a result, mobile UE may frequently change serving beam to maintain a reliable connection with the base station. It poses significant challenges to achieving reliable mobility management with minimum delay, including beam-level mobility and cell-level mobility. For this purpose, UEs and network are configured to perform an increased number of measurements on various objects or quantities, such as reference signal received power (RSRP), reference signal received quality (RSRQ), signal to interference plus noise ratio (SINR) or the like. Many of the measurements are performed frequently (e.g. every few tens of milliseconds) for an efficient monitoring of network resources, link quality, power control, handover opportunities, radio link failures and so on, and to react to relevant events in a timely manner.

[0031] These measurements, however, consume a lot of energy and time. The base station performs a beam sweep of Tx beams in respective directions, and UE measures all the Tx beams to identify the strongest one. It obviously takes a longer time than non-beamforming use cases. During performing measurements on a certain transceiver, UE cannot transmit user data using the transceiver, and the energy consumed during the measurements drains battery life. It is desirable, therefore, to perform the measurements as efficiently as possible, and to reduce the need for performing these measurements so frequently. In that way, the energy and time that was used in performing measurements can be saved.

[0032] 3 GPP has launched studies on artificial intelligence (Al) / machine learning (ML) for NR air interface, one of the use cases is AI / ML based beam measurement reduction. Fig. 2 illustrates an example of an AI / ML model inference procedure 200 for beam management (BM) for BM-Casel and BM-Case2. As shown, measurements based on Set B of beams are used as model input to an AI / ML model 210. The beam measurements may be based on use of periodic channel state information reference signals (CSLRS) and synchronization signal blocks (SSBs). Based on model output (e.g., probability of each beam in Set Ato be the Top-1 beam, predicted Ll-RSRPs), Top-l / N beam(s) among Set A of beams can be predicted and / or potentially with predicted Ll-RSRPs (depending on the labelling). The cases that Set A and Set B are different (Set B is NOT a subset of Set A), and Set B is a subset of Set A for both BM-Casel and BM- Case2, and case that Set A and Set B are the same for BM-Case2 are considered. For BM-Case 1, the measurements of Set B are used as model input to predict Top-l / N beams from Set A,which is called spatial beam prediction. For BM-Case2, the measurements from historic time instance(s) are used as model input for temporal DL beam prediction of beams from Set A, which is called time domain beam prediction.

[0033] 3 GPP Release 19 has extended the AI / ML use cases to cell-level measurement prediction for inter-cell mobility. Similar to the above-described beam-level measurement prediction, measurements based on Set B of cells may be used as model input to an AI / ML model. Based on model output (e.g., probability of each cell in Set A to be the Top-1 cell, predicted Ll-RSRPs), Top-l / N cell(s) among Set A of cells can be predicted and / or potentially with predicted Ll-RSRPs (depending on the labelling). The cell-level measurements may be derived from beam-level measurements.

[0034] In either beam-level or cell-level mobility use cases, a problem arises that if not all beams are measured, how to accurately predict the strongest beam or cell. In addition, preparing for the measurement reduction methods, for example, collecting data to train the required AI / ML models, can introduce significant cost, which may offset to some extent the gains achieved by the measurement reduction, for example in reduced signaling and energy efficiency.

[0035] Not bound to any theory, it is observed that in some situations where UE performs several measurements of the same kind, (e.g., measuring RSRP of several beams in a cell) there will be some degree of correlation (or a learnable relationship) between the values of the several measurements. The correlations can be exploited in such a way as to predict one measurement from another, or to calculate a smaller subset of measurements to perform, thus reducing the need to measure all the relevant quantities. Based on the observation, some example embodiments propose a method to obtain a mathematical relationship between measurements of the same kind (e.g., beam measurements) in a distributed manner, such that UEs can collaboratively calculate their own estimates of the relationship (using quantities derived from their own measurements), and those estimates may be aggregated at the network to obtain a network-level estimate that can be used to guide a measurement reduction algorithm.

[0036] Fig. 3 illustrates an example process 300 according to some example embodiments. As shown, the process 300 involves the base station 120 and a plurality of UEs 110. The base station 120 and UEs 110 each may comprise components, circuitries, modules, elements and / or means to perform functions corresponding to operations or steps of the process 300. The components, circuitries, modules, elements and means each may be implemented in various manners including but not limited to for example software, hardware, firmware or any combination thereof.

[0037] At 310, the base station 120 may transmit a configuration for measurement collectionto a plurality of UEs 110 served by the base station 120. The configuration may comprise configuration information for collecting and reporting beam-level and / or cell-level measurements. In some examples, the configuration information may comprise indices of a set of beams and / or cells to be measured. For instance, for a beam-level mobility use case, if the base station 120 deploys 32 beams for a cell, the configuration information may comprise indices of all the 32 beams to ensure that the UEs 110 can correctly detect the strongest beam. For a cell-level mobility use case, the configuration information may comprise indices of all neighboring cells (and also the serving cell) available to a UE and indices of beams in each cell, to ensure that the UE can correctly detect the best cell. The best cell may be understood as a cell from which the UE receives a signal with the greatest signal strength or signal quality.

[0038] In some examples, the configuration information may further comprise periodicity or time interval for measuring the set of beams and / or cells, and measurement object or quantity in association with the set of beams and / or cells. For instance, the measurement object or quantity may comprise reference signal received power (RSRP), reference signal received quality (RSRQ), signal to interference plus noise ratio (SINR) or the like.

[0039] In some examples, the configuration information may further comprise one or more criteria for reporting the measurements and a data format of the measurement report. UEs may collect and store the measurements and, when at least one of the criteria is satisfied, the UEs may report the measurements in the required data format to the base station 120, which will be described below in detail.

[0040] According to the received configuration, the UEs 110 may measure the configured set of beams and / or cells at 312 and store measurement information at 314. The UEs 110 may measure the set of beams and / or cells in a legacy way. For instance, the physical layer (Layer 1 or LI) measures respective beams and, after internal Layer 1 filtering, reports the beam specific measurements to the RRC layer (Layer 3 or L3). For beam-level measurement, the RRC layer performs Layer 3 filtering on the beam specific measurements and selects one or more strongest beams to report. For cell-level measurement, the beam specific measurements received from the physical layer may be consolidated to derive cell quality, for example by averaging the measurement of K strongest beams. The parameter K may be configured by the network for example in a RRCReconfiguration message, e.g., K=1 which means simply taking the measurement of the strongest beam as cell quality. The consolidated cell-level measurement is then filtered in a Layer 3 filter to get the cell-level Layer 3 measurement. Based on the celllevel Layer 3 measurement, UE selects at least one best cell from the configured set of cells.

[0041] Fig. 4A illustrates an example sequence 400A of beam / cell-level measurementsobtained at UEs. Each UE can measure all the beams at each full beam sweep (in each cell) and record the index of the best beam / cell as discussed above. The UE can collect the index of the best beam / cell over time, obtaining the sequence of the best beam / cell indices as a time series shown in Fig. 4A. It is worth noting that at each beam sweep (time instance), the UE can record more than one (e.g., two or more) best beams / cells.

[0042] Each UE can directly store the sequence shown in Fig. 4A, or process the sequence into a histogram and then store the histogram. In an example, said each UE can create a best beam / cell transition table 400B shown in Fig. 4B from the sequence 400A shown in Fig. 4A. The best beam / cell transition table may comprise a first column (or row) of the best beam / cell index at a time instance (e.g., beam sweep) T, and a second column (or row) of the best beam / cell index at a next time instance (e.g., beam sweep) T+l. The index pair at each row (or column) indicates a transition of the best beam / cell index over time. Then, said each UE can calculate a histogram from the best beam / cell transition table.

[0043] Fig. 4C shows an example of the histogram 400C represented by a two-dimensional matrix. As shown, the matrix may comprise a plurality of rows corresponding to the best beam / cell indices at a time instance T, and a plurality of columns corresponding to the best beam / cell indices at a next time instance T+l. The number of rows and columns in the matrix depends on the number of beams / cells configured to measure at the UE. Each element Pq at the i-th row and j-th column of the matrix may comprise the number of times (i.e., frequency) the best beam / cell transitions from the index corresponding to the i-th row to the index corresponding to the j-th column. The larger the number, the higher the probability of the corresponding transition. In another example, the frequency histogram may be optionally normalized to get a probability mass function of the transition probabilities. For example, each element Pq may be divided by a sum of elements in the i-th rowEq), obtaining the probability (e.g., in percentage) the best beam / cell transitions from the index corresponding to the i-th row to the index corresponding to the j-th column.

[0044] Fig. 4D shows an example of a probability histogram 400D generated at a UE. The probability histogram may be used at the UE to reduce beam-level or cell-level measurements, as described in detail below. However, as UEs typically have limited mobility, it is difficult for a single UE to collect enough data of best beam / cell transitions to obtain a reasonably converged histogram. In example embodiments, a collaborative method is used to collect best beam / cell index transitions data from a plurality of UEs for calculating the histogram. It can ensure that enough measurement samples are collected to cover different UE trajectories andscenarios and hence the histogram converges to predict an optimal set of beams / cells comprising the best beam / cell at a next time instance.

[0045] Returning to Fig. 3, each UE 110 may perform operations 312-314 for a number of times to collect and store the measurement information. As discussed above, the stored measurement information may comprise a sequence of indices of the best beam / cell in the order of time instances (e.g., as shown in Fig. 4A) or a frequency or probability histogram (e.g., as shown in Figs. 4C-4D). In either case, the stored information indicates index transition of the best beam or cell at the UE, which is also referred to as first information for convenience of description. Meanwhile, the UEs 110 evaluate whether the one or more criteria for reporting the first information are satisfied. If at least one (or more) criterion is satisfied, e.g., when a predefined time period has elapsed or the UE has collected a predefined amount of measurements, the UE may report the first information to the base station 120 at 316.

[0046] The base station 120 may combine the first information received from respective UEs 110 to obtain second information on index transition of the best beams / cells over time. In some examples, the base station 120 may combine the first information received from respective UEs 110 into one single cell-specific histogram. If the received first information comprises the sequence of the best beam / cell indices, the base station 120 may calculate a histogram from the first information received from respective UEs 110 as discussed above with reference to Figs. 4A-4D. If the received first information comprise a frequency histogram, the base station 120 may simply add up the frequency histograms received from respective UEs 110 together. If the received first information comprise a probability histogram (probability mass function), the base station 120 may calculate an average of the probability histograms received from respective UEs 110 with a weighting corresponding to the number of samples used to calculate the probability histogram at a corresponding UE. Since the base station 120 receives the first information from a plurality of UEs, it can readily collect enough data of beam transitions to obtain a reasonably converged histogram. In addition, as the histogram may be calculated at UEs in a collaborative manner, the process would not cause computational overburden to the base station.

[0047] In some examples, the base station 120 may transmit the cell-specific histogram as the second information to one or more UEs 110 at 322. The one or more UEs 110 may include at least some or even all of the UEs that contributed to the measurements and / or one or more UEs that did not contribute to the measurements. In some other examples, the base station 120 may further calculate a lookup table from the cell-specific histogram at 320, and transmit the lookup table as the second information to the UEs 110 at 322. For example, each row of the matrixrepresenting the histogram may be used to calculate an entry in the lookup table. The entry may indicate the best beam / cell index corresponding to the row (i.e., the best beam / cell at a current time instance), and a subset of beams / cells that UEs ought to measure. The subset of beams / cells comprises a smaller number of beams than the first set of beams / cells configured to measure at 310, and the beams / cells to measure may be determined in such a way as to improve (even maximize) the likelihood that they will contain the best beam / cell at a subsequent / next time instance and reduce (even minimize) the number of beams / cells to measure. In an example, the subset of beams / cells to measure may be determined such that the likelihood that the subset includes the best beam / cell at a next time instance is higher than or equal to a predetermined threshold. In this way, it can reduce beam / cell measurements at UE without an obvious impact on the likelihood that the UE can accurately detect the best beam / cell.

[0048] At 324, the UEs 110 may measure a second set of beams or cells based on the received second information. If the second information contains the lookup table, the UEs may determine an entry in the lookup table corresponding to the current best beam / cell and select the subset of beams / cells indicated in the entry (as the second set of beams or cells) to measure at a subsequent / next time instance. If the second information contains the histogram, the UEs may calculate a lookup table from the histogram as discussed above and then determine the second set of beams or cells to measure using the lookup table. The current best beam / cell may be obtained from the last performed beam sweep, which may be either a full beam sweep where all the beams are measured, or a partial beam sweep where a subset of beams are measured. Accordingly, the UEs may iteratively perform the operation / step 324, and the second set of beams / cells measured by the UEs may change over time according to the second information and the last measurement performed at the UE.

[0049] The process 300 provides a practical and efficient method for radio measurement reduction. Since the base station receives beam / cell transition measurements from a plurality of UEs, it can readily collect enough data of beam transitions to obtain a reasonably converged histogram. The process does not involve frequent measurement reporting, thus saving energy, bandwidth and reporting overhead. It does not take too much computational effort in calculating and using the histogram. Unlike many AI / ML models that are considered as black boxes as it is hard to understand and explain the behavior of the model, the process 300 provides a white-box method that is explainable and interpretable. As discussed above, each element in the histogram represents a best beam / cell transition probability. The histogram may also have much easier lifecycle management (LCM) than many AI / ML models. For instance, UEs canmeasure all beams in a legacy way to evaluate the histogram, and the full-beam measurements may be also used to update the histogram in an additive manner.

[0050] To evaluate the method, a simulation scenario is set up based on the reference scenario in 3GPP TR 38.843 as a seven-site, urban macro propagation environment with FR2. Each site supports three cells, and each cell has 32 beams arranged in their sector. UEs move in straight lines with a 60 km / h speed in a random initial direction. The UEs calculate the cell-level L3- RSRP measurement from the beam-level Ll-RSRP measurements as follows: after all the 32 beams have been measured in a full beam sweep, the Ll-RSRP of the beam with the maximum Ll-RSRP (the best / strongest beam) is taken and then filtered with the previous max Ll-RSRP samples to give the filtered L3-RSRP. For saving rates from 10% to 60%, the L3-RSRP obtained by measuring a reduced set of beams / cells determined by the method discussed above is compared to the L3-RSRP obtained by measuring the full set of beams / cells to calculate a mean absolute error between them. The saving rate indicates a measurement saving achieved by using the method and it can be calculated as saving rate = 1 - the number of beams / cells in the reduced set / the number of beams / cells in the full set. In addition, a hit rate is calculated as a percentage of times in which the reduced set of beams / cells determined by the method contains the true best beam / cell. The evaluation results for the beam-level measurement reduction is shown in Table 1, and the evaluation results for the cell-level measurement reduction is shown in Table 2.

[0051] Referring to Table 1 and Table 2, in each case, as the saving rate increases from 10% to 60%, the mean absolute error slightly increases, and the hit rate slightly decreases. Even when the saving rate reaches up to 60%, the mean absolute error is very small and negligible, and the hit rate remains high. The evaluation results demonstrate that the method has excellent performance in both beam-level and cell-level mobility use cases.Table 1 : Evaluation results of beam-level measurement reductionTable 2: Evaluation results of cell-level measurement reduction

[0052] Fig. 5 illustrates a method 500 according to some example embodiments. The method 500 may be implemented at a UE such as the UE 110 discussed above.

[0053] Referring to Fig. 5, the method 500 may optionally comprise, at 510, receiving a configuration for beam-level or cell-level mobility measurements from a base station 120. The configuration may comprise information on indices of a first set of beams and / or cells to measure at the UE 110. For example, in the beam-level mobility use case, the configuration may comprise information on indices of a first set of beams in a serving cell supported by the base station 120. In the cell-level mobility use case, the configuration may comprise information on indices of a first set of cells including the serving cell and one or more neighboring cells, and indices of beams in each cell of the first set. In some examples, the configuration information may further comprise periodicity or time interval for measuring the first set of beams and / or cells, measurement object or quantity such as RSRP, RSRQ and / or SINR, one or more criteria for measurement reporting, and / or data format of the measurement reporting. In some examples, the method 500 may re-use a legacy measurement configuration for the beam-level or cell-level mobility measurements, and the block 510 may be omitted.

[0054] The UE 110 may, at 520, perform measurements on the configured first set of beams or cells to determine an index of at least one (one, two or more) strongest / best beam or cell for multiple time instances and, at 530, store first information on index transition of the at least one strongest / best beam or cell over the time instances. In some examples, the first information may comprise a sequence of indices of the at least one strongest / best beam or cell in the order of the time instances. In some other examples, the first information may comprise a histogram represented by a matrix. An element in the i-th row and j -th column of the matrix may represent a frequency or probability the at least one strongest / best beam or cell transitions from an index corresponding to the i-th row to an index corresponding to the j -th column, where 1 < i < N, 1 < j < N, N is the number of beams or cells measured by the UE 110 (i.e., the number of beams or cells in the first set configured at 510). As discussed above, the histogram may be calculated from the sequence of indices of the at least one strongest / best beam or cell in the time order.

[0055] The UE 110 may, at 540, report the first information to the base station 120 and, at 550, receive second information from the base station 120 in response to the first information. The second information also indicates index transition of the at least one strongest / best beamor cell over time, and it is based on the first information provided by the UE 110 and other first information provided by other UEs. In other words, the second information comprises more measurement samples than the first information provided by the UE 110. In some examples, similar to the first information, the second information may comprise a histogram represented by a matrix. An element in the i-th row and j -th column of the matrix may represent a frequency or probability the at least one strongest / best beam or cell transitions from an index corresponding to the i-th row to an index corresponding to the j -th column, where 1 < i < N, 1 < j < N, N is the number of beams measurable to the UE 110 (i.e., the number of beams or cells in the first set configured at 510). In some other examples, the second information may comprise a lookup table comprising a plurality of entries. Each entry may indicate at least one strongest / best beam or cell at a current time instance and a second (reduced) set of beams or cells to measure at a subsequent time instance. As discussed above, the lookup table may be calculated from the histogram.

[0056] In response to the received second information, the UE 110 may, at 560, measure a second set of beams or cells based on the second information. The second set of beams or cells may include a smaller number of beams or cells than the first set of beams or cells configured at 510. The UE 110 may determine the second set of beams or cells according to the second information and a current measurement taken by the UE 110. For example, the UE 110 may determine the current strongest / best beam or cell based on the current measurement, and then retrieve the second set of beams or cells to measure at a subsequent / next time instance from the second information with the current strongest / best beam or cell. The UE 110 can determine a new strongest / best beam or cell by measuring the second set of beams or cells, and use the new strongest / best beam or cell to retrieve a new second set of beams or cells to measure at a yet subsequent / next time instance. In this way, the UE 110 may iteratively perform the operation 560, and the second set of beams or cells may change over time.

[0057] Fig. 6 illustrates a method 600 according to some example embodiments. The method 600 may be implemented at a network device such as the base station 120 discussed above.

[0058] Referring to Fig. 6, the method 600 may optionally comprise, at 610, transmitting a configuration for beam-level or cell-level mobility measurements to one or more UEs 110. The configuration may comprise information on indices of a first set of beams and / or cells to measure at the UEs 110. For example, in the beam-level mobility use case, the configuration may comprise information on indices of a first set of beams in a serving cell supported by the base station 120. In the cell-level mobility use case, the configuration may comprise information on indices of a first set of cells including the serving cell and one or moreneighboring cells, and indices of beams in each cell of the first set. In some examples, the configuration information may further comprise periodicity or time interval for measuring the first set of beams and / or cells, measurement object or quantity such as RSRP, RSRQ and / or SINR, one or more criteria for measurement reporting, and / or data format of the measurement reporting. In some examples, the method 600 may re-use a legacy measurement configuration for the beam-level or cell-level mobility measurements, and the block 610 may be omitted.

[0059] The method 600 may further comprise, at 620, receiving first information on index transition of at least one strongest / best beam or cell over time from one or more UEs 110. In some examples, the received first information may comprise a sequence of indices of the at least one strongest / best beam or cell in the time order. In some other examples, the first information may comprise a histogram represented by a matrix. An element in the i-th row and j-th column of the matrix may represent a frequency or probability the at least one strongest / best beam or cell transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1 < j < N, N is the number of beams or cells measured by the UEs 110 (i.e., the number of beams or cells in the first set configured at 610). As discussed above, the histogram may be calculated from the sequence of indices of the at least one strongest / best beam or cell in the time order.

[0060] The base station 120 may, at 630, combine the first information received from the UEs 110 to obtain second information on index transition of the at least one strongest / best beam or cell over time. In some examples, similar to the first information, the second information may comprise a histogram represented by a matrix. An element in the i-th row and j-th column of the matrix may represent a frequency or probability the at least one strongest / best beam or cell transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1 < j < N, N is the number of beams measurable to the UE 110 (i.e., the number of beams or cells in the first set configured at 610). In some other examples, the second information may comprise a lookup table comprising a plurality of entries. Each entry may indicate at least one strongest / best beam or cell at a current time instance and a second (reduced) set of beams or cells to measure at a subsequent time instance. As discussed above, the lookup table may be calculated from the histogram. In other words, the base station 120 may combine the first information received from the UEs 110 to generate the histogram, and then calculate the lookup table from the histogram.

[0061] The base station 120 may, at 640, transmit the second information to one or more UEs 110. As mentioned above, the second information transmitted to the one or more UEs 110 may comprise the histogram generated by combining the first information received from the UEs,or the lookup table calculated from the histogram. It is worth noting that the UEs to which the second information is transmitted may be different from the UEs from which the first information is received.

[0062] Some example embodiments provide an apparatus for a terminal device such as the UE 110 discussed above. The apparatus may comprise means for performing functions corresponding to steps, operations, blocks in processes, procedures, and / or methods described above with regard to the UE 110. For example, the apparatus may comprise means for performing functions corresponding to steps in the method 500 described above with respect to Fig. 5. Some example embodiments provide an apparatus for a network device such as the base station 120 discussed above. The apparatus may comprise means for performing functions corresponding to steps, operations, blocks in processes, procedures, and / or methods described above with regard to the base station 120. For example, the apparatus may comprise means for performing functions corresponding to steps in the method 600 described above with respect to Fig. 6. Means for performing the functions may comprise hardware, firmware, software, or combinations thereof.

[0063] Fig. 7 is a schematic block diagram illustrating devices in a communication system 700 according to some example embodiments. As shown in Fig. 7, the communication system 700 may comprise a terminal device 710 which may be implemented as the UE 110 discussed above, and a network device 720 which may be implemented as the base station 120 discussed above.

[0064] Referring to Fig. 7, the terminal device 710 may comprise one or more processors 711, one or more memories 712 and one or more transceivers 713 interconnected through one or more buses 714. The one or more buses 714 may be address, data, or control buses, and may include any interconnection mechanism such as series of lines on a motherboard or integrated circuit, copper cables, optical fibers, or other electrical / optical communication equipment, and the like. Each of the one or more transceivers 713 may comprise a receiver and a transmitter, which are connected to one or more antennas 716. The terminal device 710 may wirelessly communicate with the network device 720 through the one or more antennas 716. The one or more memories 712 may include computer program code or instructions 715. The one or more memories 712 and the computer program code or instructions 715 may be configured to, when executed by the one or more processors 711, cause the terminal device 710 to perform processes and steps relating to the UE 110 as described above.

[0065] The network device 720 may comprise one or more processors 721, one or more memories 722, one or more transceivers 723 and one or more network interfaces 727interconnected through one or more buses 724. The one or more buses 724 may be address, data, or control buses, and may include any interconnection mechanism such as a series of lines on a motherboard or integrated circuit, copper cables, optical fibers, or other el ectri cal / optical communication equipment, and the like. Each of the one or more transceivers 723 may comprise a receiver and a transmitter, which are connected to one or more antennas 726. The network device 720 may operate as a base station for the terminal device 710 and wirelessly communicate with the terminal device 710 through the one or more antennas 726. The one or more network interfaces 727 may provide wired or wireless communication links through which the network device 720 may communicate with other network devices, entities or functions. The one or more memories 722 may include computer program code or instructions 725. The one or more memories 722 and the computer program code or instructions 725 may be configured to, when executed by the one or more processors 721, cause the network device 720 to perform processes and steps relating to the base station 120 as described above.

[0066] The one or more processors 711, 721 discussed above may be of any appropriate type that is suitable for the local technical network, and may include one or more of general purpose processors, special purpose processor, microprocessors, a digital signal processor (DSP), one or more processors in a processor based multi-core processor architecture, as well as dedicated processors such as those developed based on Field Programmable Gate Array (FPGA) and Application Specific Integrated Circuit (ASIC). The one or more processors 711, 721 may be configured to control other elements of the terminal / network device and operate in cooperation with them to implement the procedures discussed above.

[0067] The one or more memories 712, 722 may include at least one storage medium in various forms, such as a volatile memory and / or a non-volatile memory. The volatile memory may include but not limited to for example a random access memory (RAM) or a cache. The non-volatile memory may include but not limited to for example a read only memory (ROM), a hard disk, a flash memory, and the like. Further, the one or more memories 712, 722 may include but not limited to an electric, a magnetic, an optical, an electromagnetic, an infrared, or a semiconductor system, apparatus, or device or any combination of the above.

[0068] The network device 720 can be implemented as a single network node, or disaggregated / distributed over two or more network nodes, such as a central unit (CU), a distributed unit (DU), a remote radio head-end (RRH), using different functional-split architectures and different interfaces.

[0069] It would be understood that blocks in the drawings may be implemented in various manners, including software, hardware, firmware, or any combination thereof. In someexample embodiments, one or more blocks may be implemented using software and / or firmware, for example, machine-executable instructions stored in the storage medium. In addition to or instead of machine-executable instructions, parts or all of the blocks in the drawings may be implemented, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include Field-Programmable Gate Arrays (FPGAs), Application-Specific Integrated Circuits (ASICs), Application-Specific Standard Products (ASSPs), System-on-Chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), etc.

[0070] Some example embodiments further provide a computer program comprising instructions which, when executed by an apparatus, may cause the apparatus to perform the procedures described above. The computer program instructions for carrying out procedures of the example embodiments may be written in any combination of one or more programming languages. The computer program instructions may be provided to one or more processors or controllers of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the computer program instructions, when executed by the processor or controller, cause the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The computer program instructions may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

[0071] Some example embodiments further provide a computer program product or a computer readable medium having the computer program instructions stored therein. The computer readable medium may be any tangible medium that may contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine readable medium may be a machine readable signal medium or a machine readable storage medium. A machine readable medium may include but is not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0072] As explained above and reiterated below, the present disclosure comprises, without limitation, the following example implementations.

[0073] Clause 1. An apparatus for a terminal device, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform: measuring a first set of beams to determine an index of at least one strongest beam for multiple time instances; storing first information on index transition of the at least one strongest beam over the time instances; reporting the first information to a network device; receiving, from the network device, second information on index transition of the at least one strongest beam over time, wherein the second information is based on the first information; and measuring a second set of beams based on the second information.

[0074] Clause 2. The apparatus of clause 1, wherein the second set of beams comprises a smaller number of beams than the first set of beams.

[0075] Clause 3. The apparatus of clause 1 or 2, wherein the apparatus is configured to change beams in the second set of beams over time according to the second information and a current measurement taken by the terminal device.

[0076] Clause 4. The apparatus of any of clauses 1 to 3, wherein the second information is further based on corresponding first information reported to the network device by at least one other terminal device.

[0077] Clause 5. The apparatus of any of clauses 1 to 4, wherein the apparatus is configured to perform: receiving, from the network device, a configuration comprising information on one or more of the following: indices of the first set of beams to be measured; periodicity or time interval for measuring the first set of beams; measurement object or quantity; one or more criteria for reporting the first information; and data format of the first information report.

[0078] Clause 6. The apparatus of any of clauses 1 to 5, wherein the first information is reported in a form of: a sequence of indices of the at least one strongest beam in the order of the time instances; or a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1 < j < N, N is the number of beams measured by the terminal device.

[0079] Clause 7. The apparatus of any of clauses 1 to 6, wherein the second information is in a form of: a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1 < j < N, N is the number of beams measurable to the terminal device; or a lookup table comprising entries indicating at least one strongest beam at a current time instance and the second set of beams to be measured at a subsequent time instance.

[0080] Clause 8. An apparatus for a network device, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform: receiving, from a plurality of terminal devices, first information on index transition of at least one strongest beam over time; combining the first information received from the plurality of terminal devices to obtain second information on index transition of the at least one strongest beam over time; and transmitting the second information to one or more terminal devices.

[0081] Clause 9. The apparatus of clause 8, wherein the apparatus is configured to perform: transmitting, to the plurality of terminal devices, a configuration comprising information on one or more of the following: indices of a first set of beams to be measured; periodicity or time interval for measuring the first set of beams; measurement object or quantity; one or more criteria for reporting the first information; and data format of the first information report.

[0082] Clause 10. The apparatus of clause 8 or 9, wherein the received first information is in a form of: a sequence of indices of the at least one strongest beam in the time order; or a histogram represented by a matrix where an element in the i-th row and j -th column represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j -th column, where 1 < i < N, 1< j < N, N is the number of beams measured by the terminal device.

[0083] Clause 11. The apparatus of any of clauses 8 to 10, wherein the second information is in a form of: a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1 < j < N, N is the number of beams measurable to the plurality of terminal devices; or a lookup table comprising entries indicating at least one strongest beam at a current time instance and a second set of beams to be measured at a subsequent time instance.

[0084] Clause 12. The apparatus of any of clauses 8 to 11, wherein the apparatus is configured to: combine the first information received from the plurality of terminal devices into a histogram represented by a matrix, where an element in the i-th row and j-th column of the matrix represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i< N, 1 < j < N, N is the number of beams measurable to the plurality of terminal devices; calculate a lookup table from the histogram, the lookup table comprising entries indicating at least one strongest beam at a current time instance and a second set of beams to be measured at a subsequent time instance; and transmit the lookup table as the second information to theone or more terminal devices.

[0085] Clause 13. Amethod, comprising: measuring, by a terminal device, afirst set of beams to determine an index of at least one strongest beam for multiple time instances; storing first information on index transition of the at least one strongest beam over the time instances; reporting the first information to a network device; receiving, from the network device, second information on index transition of the at least one strongest beam overtime, wherein the second information is based on the first information; and measuring, by the terminal device, a second set of beams based on the second information.

[0086] Clause 14. The method of clause 13, wherein the second set of beams comprises a smaller number of beams than the first set of beams.

[0087] Clause 15. The method of clause 13 or 14, further comprising: changing beams in the second set of beams over time according to the second information and a current measurement taken by the terminal device.

[0088] Clause 16. The method of any of clauses 13 to 15, wherein the second information is further based on corresponding first information reported to the network device by at least one other terminal device.

[0089] Clause 17. The method of any of clauses 13 to 16, further comprising: receiving, from the network device, a configuration comprising information on one or more of the following: indices of the first set of beams to be measured; periodicity or time interval for measuring the first set of beams; measurement object or quantity; one or more criteria for reporting the first information; and data format of the first information report.

[0090] Clause 18. The method of any of clauses 13 to 17, wherein the first information is reported in a form of: a sequence of indices of the at least one strongest beam in the order of the time instances; or a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1 < j < N, N is the number of beams measured by the terminal device.

[0091] Clause 19. The method of any of clauses 13 to 18, wherein the second information is in a form of: a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1 < j < N, N is the number of beams measurable to the terminal device; or a lookup table comprising entries indicating at least one strongest beam at a current time instance and the second set of beams to be measured at a subsequent time instance.

[0092] Clause 20. A method, comprising: receiving, by a network device from a plurality of terminal devices, first information on index transition of at least one strongest beam over time; combining the first information received from the plurality of terminal devices to obtain second information on index transition of the at least one strongest beam over time; and transmitting the second information to one or more terminal devices.

[0093] Clause 21. The method of clause 20, further comprising: transmitting, from the network device to the plurality of terminal devices, a configuration comprising information on one or more of the following: indices of a first set of beams to be measured; periodicity or time interval for measuring the first set of beams; measurement object or quantity; one or more criteria for reporting the first information; and data format of the first information report.

[0094] Clause 22. The method of clause 20 or 21, wherein the received first information is in a form of: a sequence of indices of the at least one strongest beam in the time order; or a histogram represented by a matrix where an element in the i-th row and j -th column represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j -th column, where 1 < i < N, 1< j < N, N is the number of beams measured by the terminal device.

[0095] Clause 23. The method of any of clauses 20 to 22, wherein the second information is in a form of: a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1 < j < N, N is the number of beams measurable to the plurality of terminal devices; or a lookup table comprising entries indicating at least one strongest beam at a current time instance and a second set of beams to be measured at a subsequent time instance.

[0096] Clause 24. The method of any of clauses 20 to 23, further comprising: combining the first information received from the plurality of terminal devices into a histogram represented by a matrix, where an element in the i-th row and j-th column of the matrix represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1< j < N, N is the number of beams measurable to the plurality of terminal devices; calculating a lookup table from the histogram, the lookup table comprising entries indicating at least one strongest beam at a current time instance and a second set of beams to be measured at a subsequent time instance; and transmitting the lookup table as the second information to the one or more terminal devices.

[0097] Clause 25. An apparatus, comprising: means for measuring a first set of beams todetermine an index of at least one strongest beam for multiple time instances; means for storing first information on index transition of the at least one strongest beam over the time instances; reporting the first information to a network device; means for receiving, from the network device, second information on index transition of the at least one strongest beam over time, wherein the second information is based on the first information; and means for measuring a second set of beams based on the second information.

[0098] Clause 26. The apparatus of clause 25, wherein the second set of beams comprises a smaller number of beams than the first set of beams.

[0099] Clause 27. The apparatus of clause 25 or 26, further comprising: means for changing beams in the second set of beams over time according to the second information and a current measurement taken by the terminal device.

[0100] Clause 28. The apparatus of any of clauses 25 to 27, wherein the second information is further based on corresponding first information reported to the network device by at least one other terminal device.

[0101] Clause 29. The apparatus of any of clauses 25 to 28, further comprising: means for receiving, from the network device, a configuration comprising information on one or more of the following: indices of the first set of beams to be measured; periodicity or time interval for measuring the first set of beams; measurement object or quantity; one or more criteria for reporting the first information; and data format of the first information report.

[0102] Clause 30. The apparatus of any of clauses 25 to 29, wherein the first information is reported in a form of: a sequence of indices of the at least one strongest beam in the order of the time instances; or a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1 < j < N, N is the number of beams measured by the terminal device.

[0103] Clause 31. The apparatus of any of clauses 25 to 30, wherein the second information is in a form of: a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1 < j < N, N is the number of beams measurable to the terminal device; or a lookup table comprising entries indicating at least one strongest beam at a current time instance and the second set of beams to be measured at a subsequent time instance.

[0104] Clause 32. An apparatus, comprising: means for receiving, from a plurality of terminal devices, first information on index transition of at least one strongest beam over time; meansfor combining the first information received from the plurality of terminal devices to obtain second information on index transition of the at least one strongest beam over time; and means for transmitting the second information to one or more terminal devices.

[0105] Clause 33. The apparatus of clause 32, further comprising: means for transmitting, to the plurality of terminal devices, a configuration comprising information on one or more of the following: indices of a first set of beams to be measured; periodicity or time interval for measuring the first set of beams; measurement object or quantity; one or more criteria for reporting the first information; and data format of the first information report.

[0106] Clause 34. The apparatus of clause 32 or 33, wherein the received first information is in a form of: a sequence of indices of the at least one strongest beam in the time order; or a histogram represented by a matrix where an element in the i-th row and j -th column represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j -th column, where 1 < i < N, 1< j < N, N is the number of beams measured by the terminal device.

[0107] Clause 35. The apparatus of any of clauses 32 to 34, wherein the second information is in a form of: a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1 < j < N, N is the number of beams measurable to the plurality of terminal devices; or a lookup table comprising entries indicating at least one strongest beam at a current time instance and a second set of beams to be measured at a subsequent time instance.

[0108] Clause 36. The apparatus of any of clauses 32 to 35, further comprising: means for combining the first information received from the plurality of terminal devices into a histogram represented by a matrix, where an element in the i-th row and j-th column of the matrix represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1< j < N, N is the number of beams measurable to the plurality of terminal devices; means for calculating a lookup table from the histogram, the lookup table comprising entries indicating at least one strongest beam at a current time instance and a second set of beams to be measured at a subsequent time instance; and means for transmitting the lookup table as the second information to the one or more terminal devices.

[0109] Clause 37. A computer-readable medium comprising instructions that, when executed by at least one processor, causes an apparatus to perform the method of any of clauses 13 to 24.

[0110] Clause 38. A computer program comprising instructions that, when executed by atleast one processor, causes an apparatus to perform the method of any of clauses 13 to 24.

[0111] Clause 39. An apparatus for a terminal device, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform: measuring a first set of cells to determine an index of at least one best cell for multiple time instances; storing first information on index transition of the at least one best cell over the time instances; reporting the first information to a network device; receiving, from the network device, second information on index transition of the at least one best cell over time, wherein the second information is based on the first information; and measuring a second set of cells based on the second information.

[0112] Clause 40. The apparatus of clause 39, wherein the second set of cells comprises a smaller number of cells than the first set of cells.

[0113] Clause 41. The apparatus of clause 39 or 40, wherein the apparatus is configured to change cells in the second set of cells over time according to the second information and a current measurement taken by the terminal device.

[0114] Clause 42. The apparatus of any of clauses 39 to 41, wherein the second information is further based on corresponding first information reported to the network device by at least one other terminal device.

[0115] Clause 43. The apparatus of any of clauses 39 to 42, wherein the apparatus is configured to perform: receiving, from the network device, a configuration comprising information on one or more of the following: indices of the first set of cells to be measured; periodicity or time interval for measuring the first set of cells; measurement object or quantity; one or more criteria for reporting the first information; and data format of the first information report.

[0116] Clause 44. The apparatus of any of clauses 39 to 43, wherein the first information is reported in a form of: a sequence of indices of the at least one best cell in the order of the time instances; or a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one best cell transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1< j < N, N is the number of cells measured by the terminal device.

[0117] Clause 45. The apparatus of any of clauses 39 to 44, wherein the second information is in a form of: a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one best cell transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1< j < N, N is the number of cells measurable to the terminal device; or a lookup table comprisingentries indicating at least one best cell at a current time instance and the second set of cells to be measured at a subsequent time instance.

[0118] Clause 46. An apparatus for a network device, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform: receiving, from a plurality of terminal devices, first information on index transition of at least one best cell over time; combining the first information received from the plurality of terminal devices to obtain second information on index transition of the at least one best cell over time; and transmitting the second information to one or more terminal devices.

[0119] Clause 47. The apparatus of clause 46, wherein the apparatus is configured to perform: transmitting, to the plurality of terminal devices, a configuration comprising information on one or more of the following: indices of a first set of cells to be measured; periodicity or time interval for measuring the first set of cells; measurement object or quantity; one or more criteria for reporting the first information; and data format of the first information report.

[0120] Clause 48. The apparatus of clause 46 or 47, wherein the received first information is in a form of: a sequence of indices of the at least one best cell in the time order; or a histogram represented by a matrix where an element in the i-th row and j -th column represents a frequency or probability the at least one best cell transitions from an index corresponding to the i-th row to an index corresponding to the j -th column, where 1 < i < N, 1 < j < N, N is the number of cells measured by the terminal device.

[0121] Clause 49. The apparatus of any of clauses 46 to 48, wherein the second information is in a form of: a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one best cell transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1 < j < N, N is the number of cells measurable to the plurality of terminal devices; or a lookup table comprising entries indicating at least one best cell at a current time instance and a second set of cells to be measured at a subsequent time instance.

[0122] Clause 50. The apparatus of any of clauses 46 to 49, wherein the apparatus is configured to: combine the first information received from the plurality of terminal devices into a histogram represented by a matrix, where an element in the i-th row and j-th column of the matrix represents a frequency or probability the at least one best cell transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i <N, 1 <j <N, N is the number of cells measurable to the plurality of terminal devices; calculate a lookup table from the histogram, the lookup table comprising entries indicating at least onebest cell at a current time instance and a second set of cells to be measured at a subsequent time instance; and transmit the lookup table as the second information to the one or more terminal devices.

[0123] Clause 51. A method, comprising: measuring, by a terminal device, a first set of cells to determine an index of at least one best cell for multiple time instances; storing first information on index transition of the at least one best cell over the time instances; reporting the first information to a network device; receiving, from the network device, second information on index transition of the at least one best cell over time, wherein the second information is based on the first information; and measuring, by the terminal device, a second set of cells based on the second information.

[0124] Clause 52. The method of clause 51, wherein the second set of cells comprises a smaller number of cells than the first set of cells.

[0125] Clause 53. The method of clause 51 or 52, further comprising: changing cells in the second set of cells over time according to the second information and a current measurement taken by the terminal device.

[0126] Clause 54. The method of any of clauses 51 to 53, wherein the second information is further based on corresponding first information reported to the network device by at least one other terminal device.

[0127] Clause 55. The method of any of clauses 51 to 54, further comprising: receiving, from the network device, a configuration comprising information on one or more of the following: indices of the first set of cells to be measured; periodicity or time interval for measuring the first set of cells; measurement object or quantity; one or more criteria for reporting the first information; and data format of the first information report.

[0128] Clause 56. The method of any of clauses 51 to 55, wherein the first information is reported in a form of: a sequence of indices of the at least one best cell in the order of the time instances; or a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one best cell transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1< j < N, N is the number of cells measured by the terminal device.

[0129] Clause 57. The method of any of clauses 51 to 56, wherein the second information is in a form of: a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one best cell transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1< j < N, N is the number of cells measurable to the terminal device; or a lookup table comprisingentries indicating at least one best cell at a current time instance and the second set of cells to be measured at a subsequent time instance.

[0130] Clause 58. A method, comprising: receiving, by a network device from a plurality of terminal devices, first information on index transition of at least one best cell over time; combining the first information received from the plurality of terminal devices to obtain second information on index transition of the at least one best cell over time; and transmitting the second information to one or more terminal devices.

[0131] Clause 59. The method of clause 58, further comprising: transmitting, from the network device to the plurality of terminal devices, a configuration comprising information on one or more of the following: indices of a first set of cells to be measured; periodicity or time interval for measuring the first set of cells; measurement object or quantity; one or more criteria for reporting the first information; and data format of the first information report.

[0132] Clause 60. The method of clause 58 or 59, wherein the received first information is in a form of: a sequence of indices of the at least one best cell in the time order; or a histogram represented by a matrix where an element in the i-th row and j -th column represents a frequency or probability the at least one best cell transitions from an index corresponding to the i-th row to an index corresponding to the j -th column, where 1 < i < N, 1 < j < N, N is the number of cells measured by the terminal device.

[0133] Clause 61. The method of any of clauses 58 to 60, wherein the second information is in a form of: a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one best cell transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1 < j < N, N is the number of cells measurable to the plurality of terminal devices; or a lookup table comprising entries indicating at least one best cell at a current time instance and a second set of cells to be measured at a subsequent time instance.

[0134] Clause 62. The method of any of clauses 58 to 61, further comprising: combining the first information received from the plurality of terminal devices into a histogram represented by a matrix, where an element in the i-th row and j-th column of the matrix represents a frequency or probability the at least one best cell transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1 < j < N, N is the number of cells measurable to the plurality of terminal devices; calculating a lookup table from the histogram, the lookup table comprising entries indicating at least one best cell at a current time instance and a second set of cells to be measured at a subsequent time instance; and transmitting the lookup table as the second information to the one or more terminal devices.

[0135] Clause 63. An apparatus, comprising: means for measuring a first set of cells to determine an index of at least one best cell for multiple time instances; means for storing first information on index transition of the at least one best cell over the time instances; reporting the first information to a network device; means for receiving, from the network device, second information on index transition of the at least one best cell over time, wherein the second information is based on the first information; and means for measuring a second set of cells based on the second information.

[0136] Clause 64. The apparatus of clause 63, wherein the second set of cells comprises a smaller number of cells than the first set of cells.

[0137] Clause 65. The apparatus of clause 63 or 64, further comprising: means for changing cells in the second set of cells over time according to the second information and a current measurement taken by the terminal device.

[0138] Clause 66. The apparatus of any of clauses 63 to 65, wherein the second information is further based on corresponding first information reported to the network device by at least one other terminal device.

[0139] Clause 67. The apparatus of any of clauses 63 to 66, further comprising: means for receiving, from the network device, a configuration comprising information on one or more of the following: indices of the first set of cells to be measured; periodicity or time interval for measuring the first set of cells; measurement object or quantity; one or more criteria for reporting the first information; and data format of the first information report.

[0140] Clause 68. The apparatus of any of clauses 63 to 67, wherein the first information is reported in a form of: a sequence of indices of the at least one best cell in the order of the time instances; or a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one best cell transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1< j < N, N is the number of cells measured by the terminal device.

[0141] Clause 69. The apparatus of any of clauses 63 to 68, wherein the second information is in a form of: a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one best cell transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1< j < N, N is the number of cells measurable to the terminal device; or a lookup table comprising entries indicating at least one best cell at a current time instance and the second set of cells to be measured at a subsequent time instance.

[0142] Clause 70. An apparatus, comprising: means for receiving, from a plurality of terminaldevices, first information on index transition of at least one best cell over time; means for combining the first information received from the plurality of terminal devices to obtain second information on index transition of the at least one best cell over time; and means for transmitting the second information to one or more terminal devices.

[0143] Clause 71. The apparatus of clause 70, further comprising: means for transmitting, to the plurality of terminal devices, a configuration comprising information on one or more of the following: indices of a first set of cells to be measured; periodicity or time interval for measuring the first set of cells; measurement object or quantity; one or more criteria for reporting the first information; and data format of the first information report.

[0144] Clause 72. The apparatus of clause 70 or 71, wherein the received first information is in a form of: a sequence of indices of the at least one best cell in the time order; or a histogram represented by a matrix where an element in the i-th row and j -th column represents a frequency or probability the at least one best cell transitions from an index corresponding to the i-th row to an index corresponding to the j -th column, where 1 < i < N, 1 < j < N, N is the number of cells measured by the terminal device.

[0145] Clause 73. The apparatus of any of clauses 70 to 72, wherein the second information is in a form of: a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one best cell transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1< j < N, N is the number of cells measurable to the plurality of terminal devices; or a lookup table comprising entries indicating at least one best cell at a current time instance and a second set of cells to be measured at a subsequent time instance.

[0146] Clause 74. The apparatus of any of clauses 70 to 73, further comprising: means for combining the first information received from the plurality of terminal devices into a histogram represented by a matrix, where an element in the i-th row and j-th column of the matrix represents a frequency or probability the at least one best cell transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1< j < N, N is the number of cells measurable to the plurality of terminal devices; means for calculating a lookup table from the histogram, the lookup table comprising entries indicating at least one best cell at a current time instance and a second set of cells to be measured at a subsequent time instance; and means for transmitting the lookup table as the second information to the one or more terminal devices.

[0147] Clause 75. A computer-readable medium comprising instructions that, when executed by at least one processor, causes an apparatus to perform the method of any of clauses 51 to 62.

[0148] Clause 76. A computer program comprising instructions that, when executed by at least one processor, causes an apparatus to perform the method of any of clauses 51 to 62.

[0149] While operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular example embodiments. Certain features that are described in the context of separate example embodiments may also be implemented in combination in a single example embodiment. Conversely, various features that are described in the context of a single example embodiment may also be implemented in multiple example embodiments separately or in any suitable sub-combination.

[0150] As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0151] Although the subject matter has been described in a language that is specific to structural features and / or method actions, it is to be understood the subject matter defined in the appended claims is not limited to the specific features or actions described above. On the contrary, the above-described specific features and actions are disclosed as an example of implementing the claims.

Claims

CLAIMS:

1. An apparatus for a terminal device, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform: measuring a first set of beams to determine an index of at least one strongest beam for multiple time instances; storing first information on index transition of the at least one strongest beam over the time instances; reporting the first information to a network device; receiving, from the network device, second information on index transition of the at least one strongest beam over time, wherein the second information is based on the first information; and measuring a second set of beams based on the second information.

2. The apparatus of claim 1, wherein the second set of beams comprises a smaller number of beams than the first set of beams.

3. The apparatus of claim 1 or 2, wherein the apparatus is configured to change beams in the second set of beams over time according to the second information and a current measurement taken by the terminal device.

4. The apparatus of any preceding claim, wherein the second information is further based on corresponding first information reported to the network device by at least one other terminal device.

5. The apparatus of any preceding claim, wherein the apparatus is configured to perform: receiving, from the network device, a configuration comprising information on one or more of the following:32indices of the first set of beams to be measured; periodicity or time interval for measuring the first set of beams; measurement object or quantity; one or more criteria for reporting the first information; and data format of the first information report.

6. The apparatus of any preceding claim, wherein the first information is reported in a form of: a sequence of indices of the at least one strongest beam in the order of the time instances; or a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1< j < N, N is the number of beams measured by the terminal device.

7. The apparatus of any preceding claim, wherein the second information is in a form of: a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1< j < N, N is the number of beams measurable to the terminal device; or a lookup table comprising entries indicating at least one strongest beam at a current time instance and the second set of beams to be measured at a subsequent time instance.

8. An apparatus for a network device, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform: receiving, from a plurality of terminal devices, first information on index transition of at least one strongest beam over time; combining the first information received from the plurality of terminal devices toobtain second information on index transition of the at least one strongest beam over time; and transmitting the second information to one or more terminal devices.

9. The apparatus of claim 8, wherein the apparatus is configured to perform: transmitting, to the plurality of terminal devices, a configuration comprising information on one or more of the following: indices of a first set of beams to be measured; periodicity or time interval for measuring the first set of beams; measurement object or quantity; one or more criteria for reporting the first information; and data format of the first information report.

10. The apparatus of claim 8 or 9, wherein the received first information is in a form of: a sequence of indices of the at least one strongest beam in the time order; or a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1< j < N, N is the number of beams measured by the terminal device.

11. The apparatus of any of claims 8-10, wherein the second information is in a form of: a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1< j < N, N is the number of beams measurable to the plurality of terminal devices; or a lookup table comprising entries indicating at least one strongest beam at a current time instance and a second set of beams to be measured at a subsequent time instance.

12. The apparatus of any of claims 8-11, wherein the apparatus is configured to perform: combining the first information received from the plurality of terminal devices into ahistogram represented by a matrix, where an element in the i-th row and j-th column of the matrix represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1 < j < N, N is the number of beams measurable to the plurality of terminal devices; calculating a lookup table from the histogram, the lookup table comprising entries indicating at least one strongest beam at a current time instance and a second set of beams to be measured at a subsequent time instance; and transmitting the lookup table as the second information to the one or more terminal devices.

13. A method, comprising: measuring, by a terminal device, a first set of beams to determine an index of at least one strongest beam for multiple time instances; storing first information on index transition of the at least one strongest beam over the time instances; reporting the first information to a network device; receiving, from the network device, second information on index transition of the at least one strongest beam over time, wherein the second information is based on the first information; and measuring, by the terminal device, a second set of beams based on the second information.

14. The method of claim 13, wherein the second set of beams comprises a smaller number of beams than the first set of beams.

15. The method of claim 13 or 14, further comprising: changing beams in the second set of beams over time according to the second information and a current measurement taken by the terminal device.

16. The method of any of claims 13 to 15, wherein the second information is further based on corresponding first information reported to the network device by at least one other terminaldevice.

17. The method of any of claims 13 to 16, further comprising: receiving, from the network device, a configuration comprising information on one or more of the following: indices of the first set of beams to be measured; periodicity or time interval for measuring the first set of beams; measurement object or quantity; one or more criteria for reporting the first information; and data format of the first information report.

18. The method of any of claims 13 to 17, wherein the first information is reported in a form of: a sequence of indices of the at least one strongest beam in the order of the time instances; or a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1< j < N, N is the number of beams measured by the terminal device.

19. The method of any of claims 13 to 18, wherein the second information is in a form of: a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1< j < N, N is the number of beams measurable to the terminal device; or a lookup table comprising entries indicating at least one strongest beam at a current time instance and the second set of beams to be measured at a subsequent time instance.

20. A method, comprising: receiving, by a network device from a plurality of terminal devices, first information on36index transition of at least one strongest beam over time; combining the first information received from the plurality of terminal devices to obtain second information on index transition of the at least one strongest beam over time; and transmitting the second information to one or more terminal devices.

21. The method of claim 20, further comprising: transmitting, to the plurality of terminal devices, a configuration comprising information on one or more of the following: indices of a first set of beams to be measured; periodicity or time interval for measuring the first set of beams; measurement object or quantity; one or more criteria for reporting the first information; and data format of the first information report.

22. The method of claim 20 or 21, wherein the received first information is in a form of: a sequence of indices of the at least one strongest beam in the time order; or a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1< j < N, N is the number of beams measured by the terminal device.

23. The method of any of claims 20 to 22, wherein the second information is in a form of: a histogram represented by a matrix where an element in the i-th row and j-th column represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1< j < N, N is the number of beams measurable to the plurality of terminal devices; or a lookup table comprising entries indicating at least one strongest beam at a current time instance and a second set of beams to be measured at a subsequent time instance.

24. The method of any of claims 20 to 23, further comprising:37combining the first information received from the plurality of terminal devices into a histogram represented by a matrix, where an element in the i-th row and j-th column of the matrix represents a frequency or probability the at least one strongest beam transitions from an index corresponding to the i-th row to an index corresponding to the j-th column, where 1 < i < N, 1 < j < N, N is the number of beams measurable to the plurality of terminal devices; calculating a lookup table from the histogram, the lookup table comprising entries indicating at least one strongest beam at a current time instance and a second set of beams to be measured at a subsequent time instance; and transmitting the lookup table as the second information to the one or more terminal devices.38

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