System for selection of timing advance acquisition mechanism in a cellular communication network

Abstract

A system includes a cellular a cellular communication network includes one or more antennas configured to exchange radio signals with a user equipment (UE). One or more computing devices execute a node, such as a gNodeB, configured to manage exchange of data with the UE using the one or more antennas. The node is configured to: receive, from the UE, a first estimate of a timing advance of data transmission between the UE and a cell of the cellular communication network, the first estimate being calculated by the user equipment; evaluate accuracy of the first estimate; and if the first estimate is not accurate, configure the UE to communicate with the cell using a RACH procedure to facilitate acquiring of the timing advance by the cellular communication network. The node may execute on a DU or a CU of the cellular communication network.

Description

Attorney Docket No. RAKU-10700WO Title: SYSTEM FOR SELECTION OF TIMING ADVANCE ACQUISITION MECHANISM IN A CELLULAR COMMUNICATION NETWORK BACKGROUND FIELD OF THE INVENTION

[0001] This invention relates to selection of a timing advance acquisition mechanism in a cellular communication network. BACKGROUND OF THE INVENTION

[0002] In modern cellular communication networks, user equipment (UE) exchanges signals with a cellular antenna coupled to a distributed unit (DU). The DU alone or in combination with a central unit (CU) implements a node, such as a gNodeB in the 5G New Radio (5G NR) standard. The gNodeB implements the processing required to establish connections to the UE, exchange data with the UE, and handoff connections to other antennas with corresponding gNodeBs.

[0003] One item of information that facilitates communication with the UE is the timing advance (TA), which is a measure of the round-trip time delay of communication between the UE and the gNodeB. The TA is used to synchronize communication between the UE and the gNodeB.s SUMMARY OF THE INVENTION

[0004] In one aspect of the invention, a system comprises a cellular a cellular communication network includes one or more antennas configured to exchange radio signals with a user equipment (UE). One or more computing devices execute a node configured to manage exchange of data with the UE using the one or more antennas. The node is configured to: receive, from the UE, a first estimate of a timing advance for dataAttorney Docket No. RAKU-10700WO transmission between the UE and a cell of the cellular communication network, the first estimate being calculated by the user equipment; evaluate accuracy of the first estimate by comparing the TA estimate received from UE with the TA acquired using uplink sync performed using RACH procedure; and if the first estimate is not accurate, configure the UE to communicate with the cell to facilitate acquiring of the timing advance by the cellular communication network. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] In order that the advantages of the invention will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through use of the accompanying drawings, in which:

[0006] Fig. 1 is a schematic block diagram illustrating a cellular communication network;

[0007] Fig.2 is a schematic block diagram of distributed gNodeB 200

[0008] Fig. 3A is a process flow diagram of a method for training a machine learning model to assess accuracy of a timing advance calculated by user equipment in accordance with an embodiment of the present invention;

[0009] Fig. 3B is a process flow diagram of a method for utilizing the machine learning model to assess accuracy of a timing advance calculated by user equipment in accordance with an embodiment of the present invention;Attorney Docket No. RAKU-10700WO

[0010] Figs. 4A and 4B are process flow diagrams of methods incorporating assessments of the accuracy of a timing advance calculated by user equipment in accordance with an embodiment of the present invention; and

[0011] Fig. 5 is a schematic block diagram of an example computing device suitable for implementing methods in accordance with embodiments according to the disclosure. DETAILED DESCRIPTION

[0012] Fig. 1 illustrates an example cellular communication network 100. The cellular communication network 100 includes a plurality of antennas 102 capable of transmitting and receiving cellular radio signals. The antennas 102 may be beam-forming antennas, directional antennas, or any type of antennas known in the art of cellular radio communication. The antennas 102 may include power amplifiers or other signal- processing electronics.

[0013] One or more antennas 102 are coupled to a radio unit (RU) 104. The radio unit may include electronic components configured to translate binary data to be transmitted into signals to be transmitted by the one or more antennas 102. Likewise, the RU 104 translates signals received from the one or more antennas 102 into binary data.

[0014] One or more radio units 104 are coupled to a distributed unit (DU) 106. Each DU 106 may be implemented as a computing device configured to receive binary data from the RUs 104 and route the binary data over a network connection to a central unit (CU 108) or other DU 106. Likewise, each DU may receive data over the network from the CU 108 or another DU 106 and transmit the data to the one or more RUs 104 for transmission.Attorney Docket No. RAKU-10700WO

[0015] An orchestrator, such as a service management and orchestration orchestrator (SMO) 110 according to the O-RAN standard, monitors the status of the network 100. For example, the SMO 110 may communicate with the RUs 104 to monitor the status of the RUs 104. The SMOs 110 may be coupled to the RUs 104 directly by a network connection or communication with the RUs 104 by way of a DU 106 connected to the RU 104 and possibly a CU connected to the DU 106.

[0016] Each RU 104, DU 106, CU 108, and the SMO 110 may be implemented according to the O-RAN. The O-RAN standard may be as published by the O-RAN alliance in the following documents, all of which are incorporated herein by reference in their entirety: O-RAN Architecture Description 9.0, O-RAN.WG1.OAD-R003-v09.00 (June 2023). O-RAN Slicing Architecture 10.0, O-RAN.WG1.Slicing-Architecture-R003- v10.00 (June 2023). O-RAN Use Cases Analysis Report 11.0, O-RAN.WG1.Use-Cases-Analysis- Report-R003-v11.00 (June 2023). O-RAN Use Cases Detailed Specification 11.0, O-RAN.WG1.Use-Cases-Detailed- Specification-R003-v11.00 (June 2023). O-RAN R1 interface: Use Cases and Requirements 4.0, O- RAN.WG2.R1UCR.v04.00 (June 2023). O-RAN Massive MIMO Use Cases Technical Report 1.0, O-RAN.WG1.mMIMO- Use-Cases-TR-v01.00 (June 2022).

[0017] User equipment (UE) 112 exchanges radio signals with one or moreAttorney Docket No. RAKU-10700WO antennas 102. Data transmitted from the UE 112 is routed by the cellular network 100 to another network, such as the Internet, or transmitted to another UE 112 by way of a different antenna 102 or beam of the same antenna 102. Likewise, data received from another network or received from another UE 112 may be transmitted to the UE by way of the antenna 102.

[0018] Referring to Fig. 2, a gNodeB 200 is an example of a node in a cellular communication network 100 that is responsible for radio communication with UE 112. The gNodeB may be considered to be a radio communication base station. The gNodeB 200 managing radio communication through an antenna 102 may execute on the DU 106 connected to the RU 104 that is connected to that antenna 102. The gNodeB 200 may also be distributed, having components executing on the DU 106 and possibly on a CU 108 to which the DU 106 is connected.

[0019] For example, the gNodeB 200 may include central unit control plane 202 (gNB-CU-CP) and a central unit user plane 204 (gNB-CU-CP) executing on the CU 108. The central unit control plane 202 and central unit user plane 204 may connect to one or more gNodeB distributed units 206 (gNB-DU 206). The central unit, composed of the central unit control plane 202 and the central unit user plane 204, may host the radio resource control (RRC) layers and packet data convergence protocol (PDCP) respectively whereas the gNB-DU 206 host the radio link control (RLC), media access control (MAC) and physical (PHY) layers. Scheduling operations take place at the gNB-DU 206, which may utilize the timing advance (TA) as determined using the approach described below. A TA may include various items of information, such as a duration of the TA (e.g., in milliseconds) and identifying information, such as a cell identifier, and possibly a beamAttorney Docket No. RAKU-10700WO identifier, for which the TA was acquired. A single DU 106 may host multiple gNB-DU 206, such as up to 512 according to the O-RAN standard.

[0020] The central unit control plane 202 may communicate with the gNB-DU 206 over a network connection F1-C. The central unit user plane 204 may communicate with the gNB-DU 206 over a network connection F1-U. The central unit control plane 202 and central unit user plane 204 may communicate with one another over an E1 connection. The communication over F1-C, F1-U, and E1 connections may be according to a protocol defined for such connections, such as according to the 3GPP standard.

[0021] Figs. 3A and 3B illustrate methods 300a, 300b that may be performed by the UE 112 and the cellular communication network 100 (hereinafter network 100). The functions described as being performed by the network 100 may be performed by the gNodeB 200, i.e., some or all of the components of the gNodeB 200 executing on a DU 106 or CU 108. Alternatively, the functions described as being performed by the network 100 may be performed by another component, such as the SMO 110 or some other computing device.

[0022] The method 300a may include configuring 302 the UE 112 to calculate timing advance (TA) based on UE capability. Configuring 302 the UE 112 to calculate TA may presuppose a UE 112 capable of doing so. In fifth generation (5G) NR (New Radio), TA is a mechanism used to adjust the timing synchronization between the UE 112 and gNodeB 200. Timing advance is a negative offset, at the UE 112, between the start of a received downlink subframe and a transmitted uplink subframe. For example, a UE 112 far from the gNodeB 200 may encounter a relatively large propagation delay so its uplink transmission is somewhat in advance as compared to a UE 112 closer to the gNodeB 200.Attorney Docket No. RAKU-10700WO The UE 112 implements the TA to promote synchronization of the downlink and uplink subframes at the gNodeB 200.

[0023] In response to step 302, the UE 112 will calculate 304 TA for cells, and possibly beams of cells, from which the UE 112 receives radio signals. A cell may be defined as an antenna 102 (which may be a group of antennas performing beam forming) having an associated identifier and through which the UE 112 may exchange radio signals. The cell may include individual beams (e.g., angular sectors emanating from the antenna 102) that can be individually controlled to transmit and receive information from the UE 112. Accordingly, for each cell, and possibly for some or all beams in which the UE 112 is located, the UE 112 may calculate a TA. For example, the TA may be calculated as, or as a function of, a time difference between a time stamp in a packet of data received by the UE 112 and a time of receipt of the packet. The TA may be calculated based on previously calculated TA values. For example, movement toward or away from the antenna 102 of a cell may be modeled based on decreasing or increasing TA values, respectively. Future TA values may then be calculated assuming a linear decrease or increase in TA values or other curve fit or other model defined by the prior TA values.

[0024] The method 300a may include reporting 306, by the UE 112, the TA to the network 100. The TA may be reported as an individual TA, a statistical characterization of multiple TA values calculated during a reporting period, e.g., some or all of an average, minimum, maximum, or other characterization.

[0025] The UE 112 may report 306 other information (“state data”) that may facilitate assessment of the accuracy of the TA value. For example, the state data a speed and / or trajectory of the TA may be reported 306. The speed and / or trajectory may beAttorney Docket No. RAKU-10700WO derived from readings of a global positioning system (GPS) receiver, an accelerometer, or from trends exhibited by TA values over time (e.g., the rate of change in TA values over time). In general, the accuracy of TA values calculated by the UE 112 will decrease with increase in the speed and increase in the variation in speed of the UE 112.

[0026] The state data may include a metric of received signal strength for the cell, or a beam of a cell, for which a TA is reported. For example, the received signal strength of the signal of the cell, or a beam of a cell, when packets were received from which a TA was calculated.

[0027] The network 100 receives the TA (hereinafter “UE TA”) and state data and further determines 308 a TA (hereinafter network TA). For example, the network 100 may use random access channel (RACH) messages exchanged with the UE 112 to calculate the network TA. Calculation of the TA by the network 100 using RACH messages is less subject to errors than calculations of TA performed by the UE 112. The manner by which the network TA is calculated may be according to any approach known in the art. In the method 300a and other methods disclosed herein, RACH procedure based TA calculation may be replaced with determination of the UE’s TA based on processing of uplink (UL) physical uplink shared channel (PUSCH) data transmitted by the UE 112 in the UL.

[0028] The method 300a may include determining 310 an error in the UE TA. For example, a difference between the network TA and the UE TA may be calculated, e.g., a UE TA calculated for a time period may be compared to a network TA calculated for the same time period or an adjacent time period where the UE TA and network TA cannot be calculated for the same time period.Attorney Docket No. RAKU-10700WO

[0029] Steps 304-310 may be performed multiple times, possibly for multiple UE 112 and multiple cells and beams. Each iteration of steps 304-310 may result in a training data entry. The inputs of the training data entry may include the UE TA and any other state data reported at step 306 with the TA. The output of the training data entry may be the error determined at step 310.

[0030] The method 300a may include training 312 a machine learning model using the training data entries. The machine learning model may be any machine learning model known in the art, such as a neural network, deep neural network (DNN), convolution neural network (CNN), logistic regression machine learning model, Bayesian network, genetic algorithm, or the like.

[0031] For example, each training data entry may be processed by the machine learning model to obtain an estimated error. The estimated error may be compared to the error in the training data entry. A training algorithm may then update parameters of the machine learning model according to a difference between the estimated error and the error in the training data entry. In this manner, the machine learning model is trained to estimate the error in a UE TA and corresponding state data. In some embodiments, the desired output of each training data is a binary decision: whether the error is acceptable or not. Accordingly, the machine learning model is trained to output such a binary decision.

[0032] The training of step 312 may be ongoing and may continue while the machine learning model is utilized: steps 304-310 may continue to be performed to generate additional training data entries that may be used to further train the machine learning model.Attorney Docket No. RAKU-10700WO

[0033] Fig.3B illustrates a method 300b that may be executed by the network 100 using the machine learning model trained at step 312. The method 300b may be performed for each cell, and possibly for each beam of each cell, within which the UE 112 is located. The method 300b may include performing steps 302, 304, and 306 as described above. The network 100 may receive the reported TA and state data and evaluate 324 whether the TA is accurate. Step 324 may include evaluating the TA and state data using the machine learning model trained at step 312. For example, the TA and state data may be processed using the machine learning model to obtain an estimated error. If the estimated error is found 326 to be less than a threshold error, the TA may be deemed to be accurate. Otherwise, the TA may be deemed to be inaccurate. In some embodiments, the machine learning model outputs a binary decision, i.e., a decision as to whether the TA is sufficiently accurate or not.

[0034] If the TA is found 326 to be accurate, the TA reported at step 306 is used 328 for synchronization with respect to the cell, and possibly a beam of the cell, with respect to the TA was calculated. If not, a TA may be determined 330 using RACH as described above. If the TA is not found to be accurate, step 330 may include configuring the UE 112 to no longer calculate the TA and to instead use RACH to facilitate measurement of the TA by the network 100 until a subsequent time when the UE reported TA values are more accurate.

[0035] The TA, as acquired using either of the approaches described above, may be used to synchronize communication with the gNodeB 200 to which the UE 112 is currently connected or to which the connection is handed off. The manner in which theAttorney Docket No. RAKU-10700WO TA is used may be according to the O-RAN standard referenced above, the 3GPP 5G NR standard, or any other cellular communication standard.

[0036] Although a machine learning model is described in the methods 300a, 300b, other approaches for assessing accuracy may also be used. For example, pre-defined rules or logic may be used to evaluate the TA and possibly the state data to assess accuracy of the TA. The output of the pre-defined rules or logic may then be used in place of the output of the machine learning model described above.

[0037] Figs.4A and 4B illustrate example methods 400a, 400b in which the method 300b may be utilized. A handoff from the cell that the UE 112 is currently connected (“the serving cell”) is typically triggered by the UE 112 moving out of the cell and therefore experiencing a corresponding weakening of the radio signals transmitted between the UE 112 and the antenna 102 of the serving cell. Accordingly, it is advantageous to avoid involving the serving cell when determining the TA of a candidate cell to which a connection to the UE may be handed off.

[0038] For example, the Third Generation Partnership Project (3GPP) established a standard (38.300 CR version 17.6.0) for an “early TA acquisition procedure” that is performed before a cell switch towards one more candidate cells that are different from a current serving cell. In this standard, the early TA acquisition procedure is triggered by a physical downlink control channel (PDCCH) order and invokes configuration of the UE 112 using a radio resource control (RRC) message to perform TA calculation based on UE capability. The UE 112 transmits the estimated TA to the gNodeB of the serving cell. The serving cell transmits the TA value in an L1 / L2 triggered mobility (LTM) cell switch in a command media access code (MAC) control element (CE) when triggering an LTM cellAttorney Docket No. RAKU-10700WO switch. The UE performs TA measurement for the candidate cells after being configured by RRC, but the exact time the UE performs TA measurement depends on the UE implementation. The UE applies the TA value measured by itself and performs LTM without using RACH upon receiving the cell switch command.

[0039] Using the approach described below, the machine learning model may be used to determine whether to perform TA acquisition using calculations of the UE 112 alone or by gNodeB in cooperation with the UE 112 using RACH. Specifically, the method 300b may advantageously be used to determine whether the UE 112 can accurately determine the TA for a candidate cell (and possibly a specific beam of the candidate cell) without involving the gNodeB of the serving cell.

[0040] Referring specifically to Fig.4A, the method 400a may include configuring 402, by the gNB-CU-CP 202, the UE 112 with LTM to use a gNB-DU 206 as the serving gNB-DU 206a to which the UE 112 will connect and exchange data. Step 402 may involve actions by the UE 112 and serving gNB-DU 206a and may be performed as defined in the 5G NR and / or O-RAN standards.

[0041] In response to step 402 as part of configuration, the UE 112 may transmit 404 an RRC message to the gNB-CU-CP 202, the message indicating capability of the UE 112, such as capability of the UE 112 to calculate TA. If the UE 112 is not capable of calculating TA, the message sent at step 404 may so indicate and the method 4A may end, e.g., TA will be determined using RACH or other conventional approach without calculating of the TA by the UE 112.

[0042] The gNB-CU-CP 202 receives the RRC message indicating capability of the UE 112 to calculate TA and sets up 406 LTM in the new serving gNB-DU 206a. TheAttorney Docket No. RAKU-10700WO gNB-CU-CP 202 further transmits 408 a UE context setup request to the serving gNB-DU 206a. The request may include a parameter instructing the serving gNB-DU 206a that the UE 112 will be calculating the TA based on UE capability. For example, a parameter such as “UE_CAPA_BASED_TA,” may be used to indicate this UE configuration. The serving gNB-DU 206a responds to the request of step 408 by setting up a context for the UE 112 and transmitting 410 a UE context setup response including the LTM candidate cell configuration and storing the TA configuration and completion of setting up of the context.

[0043] The gNB-CU-CP 202 may further transmit 412 an RRC message to the UE 112 in response to the UE context setup request of step 408. The RRC message may include an LTM target cell configuration that instructs the UE 112 to perform TA calculation with respect to a target cell (and possibly a specific beam of the target cell) of a candidate gNB- DU 206, such as the illustrated gNB-DU 206b. The RRC message may further instruct the UE 112 to configure itself to calculate TA with respect to the target cell (and possibly a specific beam of the target cell) and to report the TA calculations periodically, such as according to a period specified in the RRC. The gNB-CU-CP 202 is able to instruct the UE 112 to calculate TA based on capability of the UE reported at step 404.

[0044] In response to the RRC message of step 412, the UE 112 configures itself according to the LTM target cell configuration. The UE 112 further begins to calculate 414 TA with respect to the target cell and possibly a beam of the target cell. As noted above, the TA may be one or more TA values or the above-listed statistical characterization thereof. The UE 112 further reports 416 the calculated TA to the gNB-CU-CP 202 according to the period specified in the RRC message of step 412 or a default period. The UE 112 may report 416 the calculated TA in an RRC message transmitted to the gNB-CU-CP 202. TheAttorney Docket No. RAKU-10700WO reports of step 416 may include state data of the UE 112 as defined above with respect to the methods 300a and 300b.

[0045] The gNB-CU-CP 202 may then evaluate 418 the TA, and possibly the state data, and determine whether the TA is accurate. Step 418 may include evaluating 418 the TA, and possibly the state data, using a machine learning model as described above with respect to the method 300b. The machine learning model may be a machine learning model trained according to the method 300a. The evaluation 418 may include determining the accuracy of the UE reported TA by comparing with the TA acquired using RACH procedure or, in the case that the UE is configured to use the UE calculated TA, by observing whether the UL data sent over UL PUSCH channel is synchronized. If the UL data is well synchronized (e.g., within a predefined tolerance), the TA calculation at the UE can be considered accurate.

[0046] If the TA is found to be accurate according to step 418, then the handoff from the serving gNB-DU 206a to the candidate gNB-DU 206b may be performed using the TA calculated at step 414 or a TA calculated by the UE subsequent to step 414. Specifically, the handoff from the serving gNB-DU 206a to the candidate gNB-DU 206b may be performed without the candidate gNB-DU 206b using RACH to measure TA with respect to the UE 112. For example, the TA from step 414 may be transmitted by the gNB- CU-CP 202 to the candidate gNB-DU 206b or the UE 112 may transmit the TA from step 414 directly to the candidate gNB-DU 206b. Fig. 4C, described below, provides one example approach for performing a handoff.

[0047] Subsequent steps of the method 400a may be performed in response to the TA from step 414 being found to be inaccurate at step 418. Specifically, the method 400aAttorney Docket No. RAKU-10700WO may be used to reconfigure the UE 112 to stop calculating TA and shift TA acquisition to using the RACH procedure with the candidate gNB-DU 206b.

[0048] The method 400a may include the gNB-CU-CP 202 transmitting 430 a UE context modification request to the serving gNB-DU 206a. The request may include a parameter instructing the serving gNB-DU 206a that the UE 112 will not be calculating the TA. For example, a parameter such as “RACH_BASED_TA,” may be used. The serving gNB-DU 206a responds to the request of step 408 by setting up a context for the UE 112 and transmitting 432 a UE context modification response acknowledging the request and completion of modification of the context.

[0049] In response to the context modification request from step 430, the serving gNB-DU 206a may transmit 434 an instruction to the UE 112 to stop calculating TA and to perform RACH with the candidate gNB-DU 206b to acquire TA. For example, step 434 may include transmitting a PDCCH order including an identifier of a cell of the candidate gNB-DU 206b, the PDCCH may instruct the UE 112 to perform RACH-based measuring of TA with respect to the candidate gNB-DU 206b and to stop calculating TA. In response to the instruction from step 434, the UE 112 may transmit 436 a random-access request to the candidate gNB-DU 206b, which responds by transmitting 438 a random- access response to the UE 112. The exchange of the random-access response and the random-access request of steps 436 and 438 may be accompanied by the candidate gNB- DU 206b measuring the TA with respect to the UE 112. The candidate gNB-DU 206b may transmit 440 the measured TA to the serving gNB-DU 206a via the gNB-CU or directly to the serving gNB-DU (if a gNB-DU to gNB-DU interface is introduced in future technologies like 6G). The candidate gNB-DU 206b may further transmit 442 a UE contextAttorney Docket No. RAKU-10700WO modification request to the gNB-CU-CP 202, the context modification request including the measured TA. The gNB-CU-CP 202 may initiate context modification procedure for the UE 112 stored by the gNB-CU-CP 202 to include the measured TA in association with the identifier of the candidate gNB-DU 206b, e.g., a cell identifier of a cell of the candidate gNB-DU 206b. The gNB-CU-CP 202 may transmit 444 an acknowledgement of the context modification request to the candidate gNB-DU 206b.

[0050] The method 400a may further include performing the illustrates steps 450- 462 corresponding to a LTM handoff between a cell of the serving gNB-DU 206a and the candidate gNB-DU 206b. Note that the method 400a may be performed with respect to multiple candidate gNB-DUs 206b such that the method 400a includes selecting from among multiple candidate gNB-DUs 206b. Variation in the method 400a for the case where TA is calculated by the UE 112 as compared to the candidate gNB-DUs 206b is also described below.

[0051] The illustrated steps 450-462 of the method 400a may be executed in response to any criteria specified in the 5G NR, O-RAN, or other cellular communication standard that would trigger a handoff between cells. In particular, steps 450-462 may be performed in response to L1 measurements of the UE 112 with respect to the candidate gNB-DU 206b meeting a predefined criterion. For example, steps 450-462 may be invoked in response to L1 measurements of the UE 112 with respect to the candidate gNB-DU 206b being better than measurements of the UE 112 with respect to a cell of the serving gNB- DU 206a (e.g., a stronger signal).

[0052] The method 400a may include the gNB-CU-CP 202 transmitting 450 a context modification request to the serving gNB-DU 206a, e.g., a serving gNB-DU 206aAttorney Docket No. RAKU-10700WO of the UE. The context modification request may include one or more TAs, each with a corresponding cell identifier and / or beam ID with respect to which the TA was measured. The TAs may be TAs calculated for cells, and possibly beams of cells, of the candidate gNB-DU 206b. The TAs may be one or both of (a) TAs measured using RACH and (b) TAs calculated by the UE 112 and determine to be accurate as described above. The serving gNB-DU 206a receives the context modification request and transmits 452 a context modification response.

[0053] The UE 112 may further report 454 L1 measurements to the serving gNB- DU 206a, such as an intra or inter-frequency L1 measurement report for one or more cells and one or more beams of cells of the candidate gNB-DU 206b.

[0054] The serving gNB-DU 206a may select 456 a cell, and possibly a beam of the candidate gNB-DU 206b based on the L1 measurements from step 454, e.g., based on signal strength or any other criteria known in the art. The serving gNB-DU 206a may then transmit 458 a downlink (DL) media access code (MAC) control element (CE) to the UE 112. The MAC CE may include the cell identifier of the cell selected at step 456, and possibly a beam identifier of a beam selected at step 456. The MAC CE may further includes the TA of the cell, and possibly the TA of the beam, selected at step 456.

[0055] The UE 112 will then use 460 the TA received in the MAC CE and perform 462 a handoff to the target gNB-DU 206b, e.g., to the cell and possibly the beam of the target gNB-DU 206b as selected at step 456. The handoff of step 462 may be performed without performing RACH with respect to the candidate gNB-DU 206b.

[0056] Fig.4B illustrates a method 400b that may be performed as an alternative to the method 400a. In the method 400b, the serving gNB-DU 206a performs theAttorney Docket No. RAKU-10700WO evaluation of whether a TA calculated by the UE 112 is accurate. The method 400b therefore has the advantage of reducing loading of the gNB-CU-CP 202. The illustrated steps of the method 400b may include performing some or all of steps 402, 404, 406, 408, and 410 as described above with respect to the method 400a.

[0057] The method 400b may differ from the method 400a with respect to step 470, which is performed in place of step 412 of the method 400a. At step 470, an RRC reconfiguration message is transmitted from the gNB-CU-CP 202 to the UE 112. The RRC message from step 470 may include an LTM target cell configuration that instructs the UE 112 to perform TA calculation with respect to a target cell (and possibly a beam) of the candidate gNB-DU 206b. The RRC message may further instruct the UE 112 to configure itself to calculate TA with respect to the target cell (and possibly a specific beam of the target cell) and to report the TA calculations periodically, such as according to a period specified in the RRC. The RRC reconfiguration of step 470 may further include a parameter or other data that instructs the UE 112 to transmit the TA calculations to the serving gNB-DU 206a.

[0058] In response to the RRC message of step 470, the UE 112 configures itself according to the LTM target cell configuration. The UE 112 further begins to calculate 472 TA with respect to the target cell and possibly a beam of the target cell. The UE 112 further reports 474 the TA to the serving gNB-DU 206a as instructed by the RRC message of step 470. The UE 112 calculates 472 and reports 474 TAs according to the period specified in the RRC message of step 412 or a default period. The UE 112 may report 474 the TA in a MAC CE message transmitted to the serving gNB-DU 206a. The reports of step 474 may include state data of the UE 112 as defined above with respect to the methods 300a andAttorney Docket No. RAKU-10700WO 300b.

[0059] The serving gNB-DU 206a may then evaluate 476 the TA reported at step 474, and possibly the state data, and determine whether the TA is accurate. Step 476 may include evaluating 476 the TA, and possibly the state data, using a machine learning model as described above with respect to the method 300b. The machine learning model may be a machine learning model trained according to the method 300a. The evaluation of step 476 may be performed as described above with respect to step 418.

[0060] If the TA is found to be accurate according to step 476, then the handoff from the serving gNB-DU 206a to the candidate gNB-DU 206b may be performed using the TA calculated at step 474 or a TA calculated by the UE 112 subsequent to step 474. For example, the handoff may be performed by performing steps 442, 444, and 450-462 as described above. Specifically, the handoff from the serving gNB-DU 206a to the candidate gNB-DU 206b may be performed without the candidate gNB-DU 206b using RACH to measure TA with respect to the UE 112. For example, the TA from step 472 may be transmitted by the serving gNB-DU 206a to the candidate gNB-DU 206b or the UE 112 may transmit the TA from step 472 directly to the candidate gNB-DU 206b.

[0061] If the TA is not found to be accurate at step 476, steps 434-440 (see Fig.4A and corresponding discussion) may be performed to acquire the TA and LTM handoff may be performed according to steps 442, 444 and 450-462 as described above with respect to the method 400a.

[0062] Fig. 5 is a block diagram illustrating an example computing device 500. Computing device 500 may be used to perform various procedures, such as those discussed herein. Each RU 104, DU 106, CU 108, SMO 110, and UE 112 may have some or all ofAttorney Docket No. RAKU-10700WO the attributes of the computing device 500.

[0063] Computing device 500 includes one or more processor(s) 502, one or more memory device(s) 504, one or more interface(s) 506, one or more mass storage device(s) 508, one or more Input / output (I / O) device(s) 510, and a display device 530 all of which are coupled to a bus 512. Processor(s) 502 include one or more processors or controllers that execute instructions stored in memory device(s) 504 and / or mass storage device(s) 508. Processor(s) 502 may also include various types of computer-readable media, such as cache memory.

[0064] Memory device(s) 504 include various computer-readable media, such as volatile memory (e.g., random access memory (RAM) 514) and / or nonvolatile memory (e.g., read-only memory (ROM) 516). Memory device(s) 504 may also include rewritable ROM, such as Flash memory.

[0065] Mass storage device(s) 508 include various non-transitory computer readable media, such as magnetic tapes, magnetic disks, optical disks, solid-state memory (e.g., Flash memory), and so forth. As shown in Fig.5, a particular mass storage device is a hard disk drive 524. Various drives may also be included in mass storage device(s) 508 to enable reading from and / or writing to the various computer readable media. Mass storage device(s) 508 include removable media 526 and / or non-removable media.

[0066] I / O device(s) 510 include various devices that allow data and / or other information to be input to or retrieved from computing device 500. Example I / O device(s) 510 include cursor control devices, keyboards, keypads, microphones, monitors or other display devices, speakers, printers, network interface cards, modems, lenses, CCDs or other image capture devices, and the like.Attorney Docket No. RAKU-10700WO

[0067] Display device 530 includes any type of device capable of displaying information to one or more users of computing device 500. Examples of display device 530 include a monitor, display terminal, video projection device, and the like.

[0068] Interface(s) 506 include various interfaces that allow computing device 500 to interact with other systems, devices, or computing environments. Example interface(s) 506 include any number of different network interfaces 520, such as interfaces to local area networks (LANs), wide area networks (WANs), wireless networks, and the Internet. Other interface(s) include user interface 518 and peripheral device interface 522. The interface(s) 506 may also include one or more peripheral interfaces such as interfaces for printers, pointing devices (mice, track pad, etc.), keyboards, and the like.

[0069] Bus 512 allows processor(s) 502, memory device(s) 504, interface(s) 506, mass storage device(s) 508, I / O device(s) 510, and display device 530 to communicate with one another, as well as other devices or components coupled to bus 512. Bus 512 represents one or more of several types of bus structures, such as a system bus, PCI bus, IEEE 1394 bus, USB bus, and so forth.

[0070] For purposes of illustration, programs and other executable program components are shown herein as discrete blocks, although it is understood that such programs and components may reside at various times in different storage components of computing device 500, and are executed by processor(s) 502. Alternatively, the systems and procedures described herein can be implemented in hardware, or a combination of hardware, software, and / or firmware. For example, one or more application specific integrated circuits (ASICs) can be programmed to carry out one or more of the systems and procedures described herein.Attorney Docket No. RAKU-10700WO

[0071] In the above disclosure, reference has been made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific implementations in which the disclosure may be practiced. It is understood that other implementations may be utilized and structural changes may be made without departing from the scope of the present disclosure. References in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0072] Implementations of the systems, devices, and methods disclosed herein may comprise or utilize a special purpose or general-purpose computer including computer hardware, such as, for example, one or more processors and system memory, as discussed herein. Implementations within the scope of the present disclosure may also include physical and other computer-readable media for carrying or storing computer-executable instructions and / or data structures. Such computer-readable media can be any available media that can be accessed by a general purpose or special purpose computer system. Computer-readable media that store computer-executable instructions are computer storage media (devices). Computer-readable media that carry computer- executable instructions are transmission media. Thus, by way of example, and notAttorney Docket No. RAKU-10700WO limitation, implementations of the disclosure can comprise at least two distinctly different kinds of computer-readable media: computer storage media (devices) and transmission media.

[0073] Computer storage media (devices) includes RAM, ROM, EEPROM, CD- ROM, solid state drives (“SSDs”) (e.g., based on RAM), Flash memory, phase-change memory (“PCM”), other types of memory, other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store desired program code means in the form of computer-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer.

[0074] An implementation of the devices, systems, and methods disclosed herein may communicate over a computer network. A “network” is defined as one or more data links that enable the transport of electronic data between computer systems and / or modules and / or other electronic devices. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a computer, the computer properly views the connection as a transmission medium. Transmissions media can include a network and / or data links, which can be used to carry desired program code means in the form of computer- executable instructions or data structures and which can be accessed by a general purpose or special purpose computer. Combinations of the above should also be included within the scope of computer-readable media.

[0075] Computer-executable instructions comprise, for example, instructions and data which, when executed at a processor, cause a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function orAttorney Docket No. RAKU-10700WO group of functions. The computer executable instructions may be, for example, binaries, intermediate format instructions such as assembly language, or even source code. Although the subject matter has been described in language specific to structural features and / or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the described features or acts described above. Rather, the described features and acts are disclosed as example forms of implementing the claims.

[0076] Those skilled in the art will appreciate that the disclosure may be practiced in network computing environments with many types of computer system configurations, including, an in-dash vehicle computer, personal computers, desktop computers, laptop computers, message processors, hand-held devices, multi-processor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, mobile telephones, PDAs, tablets, pagers, routers, switches, various storage devices, and the like. The disclosure may also be practiced in distributed system environments where local and remote computer systems, which are linked (either by hardwired data links, wireless data links, or by a combination of hardwired and wireless data links) through a network, both perform tasks. In a distributed system environment, program modules may be located in both local and remote memory storage devices.

[0077] Further, where appropriate, functions described herein can be performed in one or more of: hardware, software, firmware, digital components, or analog components. For example, one or more application specific integrated circuits (ASICs) can be programmed to carry out one or more of the systems and procedures describedAttorney Docket No. RAKU-10700WO herein. Certain terms are used throughout the description and claims to refer to particular system components. As one skilled in the art will appreciate, components may be referred to by different names. This document does not intend to distinguish between components that differ in name, but not function.

[0078] It should be noted that the sensor embodiments discussed above may comprise computer hardware, software, firmware, or any combination thereof to perform at least a portion of their functions. For example, a sensor may include computer code configured to be executed in one or more processors, and may include hardware logic / electrical circuitry controlled by the computer code. These example devices are provided herein purposes of illustration, and are not intended to be limiting. Embodiments of the present disclosure may be implemented in further types of devices, as would be known to persons skilled in the relevant art(s).

[0079] At least some embodiments of the disclosure have been directed to computer program products comprising such logic (e.g., in the form of software) stored on any computer useable medium. Such software, when executed in one or more data processing devices, causes a device to operate as described herein.

[0080] While various embodiments of the present disclosure have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the disclosure. Thus, the breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. The foregoing description hasAttorney Docket No. RAKU-10700WO been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. Further, it should be noted that any or all of the aforementioned alternate implementations may be used in any combination desired to form additional hybrid implementations of the disclosure.

Claims

Attorney Docket No. RAKU-10700WO Claims:

1. A method comprising: receiving, by a cellular communication network, from a user equipment (UE) a first estimate of a timing advance (TA) of data transmission between the UE and a cell of the cellular communication network, the first estimate being calculated by the user equipment; evaluating, by the cellular communication network, accuracy of the first estimate; determining, by the cellular communication network, that the first estimate is not accurate; and in response to determining that the timing advance is not accurate, configuring, by the cellular communication network, the UE to acquire timing advance using a random access channel (RACH) procedure with the cell to facilitate acquiring of the timing advance by the cellular communication network.

2. The method of claim 1, wherein the method further comprises: evaluating accuracy of the first estimate by evaluating the first estimate using a machine learning model; evaluating, by the cellular communication network, accuracy of the first estimate by comparing the first estimate with a TA acquired using the RACH procedure; and. evaluating, by the cellular communication network, accuracy of the first estimate by observing whether uplink (UL) data sent over an UL physical uplink shared channel (PUSCH) channel is synchronized.Attorney Docket No. RAKU-10700WO 3. The method of claim 1, further comprising receiving, by the cellular communication network, state data from the UE, the state data describing a state of operation of the UE; wherein evaluating accuracy of the first estimate comprises evaluating the first estimate and the state data.

4. The method of claim 3, wherein the state data includes a speed of the UE.

5. The method of claim 3, wherein evaluating accuracy of the first estimate comprises evaluating the first estimate and the state data using a machine learning model.

6. The method of claim 1, wherein evaluating accuracy of the first estimate is performed by a component of a gNodeB executing on a distributed unit (DU) of the cellular communication network.

7. The method of claim 1, wherein evaluating accuracy of the first estimate is performed by a component of a gNodeB executing on a central unit (CU) of the cellular communication network.

8. The method of claim 1, further comprising: prior to receiving the first estimate, configuring, by the cellular communication network, the UE to estimate the timing advance based on UE capability.Attorney Docket No. RAKU-10700WO 9. The method of claim 1, wherein the first estimate further includes one or more of a cell identifier, beam identifier, or a duration for the timing advance.

10. A cellular communication network comprising: one or more antennas configured to exchange radio signals with a user equipment (UE); and one or more computing devices executing a node configured to manage exchange of data with the UE using the one or more antennas, the node configured to: receive, from the UE, a first estimate of a timing advance required for uplink (UL) data transmission between the UE and a cell of the cellular communication network, the first estimate being calculated by the user equipment; evaluate accuracy of the first estimate; and if the first estimate is not accurate, configure the UE to acquire timing advance using a random access channel (RACH) procedure with the cell to facilitate acquiring of the timing advance by the cellular communication network.

11. The cellular communication network of claim 10, wherein the node is configured to evaluate accuracy of the first estimate by evaluating the first estimate using a machine learning model.

12. The cellular communication network of claim 10, wherein the node is further configured to receiving state data from the UE, the state data describing a state ofAttorney Docket No. RAKU-10700WO operation of the UE; wherein the node is configured to evaluate accuracy of the first estimate by evaluating the first estimate and the state data.

13. The cellular communication network of claim 12, wherein the state data includes a speed of the UE.

14. The cellular communication network of claim 12, wherein the node is configured to evaluate accuracy of the first estimate by evaluating the first estimate and the state data using a machine learning model.

15. The cellular communication network of claim 10, wherein the node executes on a distributed unit (DU) of the cellular communication network.

16. The cellular communication network of claim 10, wherein the node executes on a central unit (CU) of the cellular communication network.

17. The cellular communication network of claim 11, wherein the node is further configured to: prior to receiving the first estimate, configure the UE to estimate the timing advance using capability of the UE.

18. The cellular communication network of claim 11, wherein the firstAttorney Docket No. RAKU-10700WO estimate further includes one or more of a cell identifier, beam identifier, or a duration for the timing advance.

19. A computing device configured to: receive a first message from a cellular communication network, the first message instructing reconfiguration to calculate timing advance with respect to a cell of the cellular communication network; in response to the first message, calculate a first estimate of the timing advance and report the first estimate to a second node of the cellular communication network; and receive a second message from the cellular communication network subsequent to the first message, the second message instructing reconfiguration to communicate with the cell using a random access channel (RACH) procedure to facilitate acquiring of the timing advance by the cellular communication network.

20. A non-transitory computer-readable medium storing executable code that, when executed by one or more processing devices, cause the one or more processing devices to: receive, from a user equipment (UE), a first estimate of a timing advance of data transmission between the UE and a cell of a cellular communication network, the first estimate being calculated by the user equipment; evaluate accuracy of the first estimate; and if the first estimate is not accurate, configure the UE to communicate with the cellAttorney Docket No. RAKU-10700WO to facilitate acquiring of the timing advance by the cellular communication network.

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