Patent Publication Number: US-2021194572-A1

Title: User equipment parameter determination method and apparatus, and storage medium and base station

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is the U.S. national stage of Application No. PCT/CN2019/096463, filed on Jul. 18, 2019, Priority under 35 U.S.C. § 119(a) and 35 U.S.C. § 365(b) is claimed from Chinese Patent Application No. 201811012648.5, filed on Aug. 31, 2018, the entire disclosure of which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure generally relates to radio communication technology field, and more particularly, to a User Equipment (UE) parameter determination method and apparatus, a storage medium and a base station. 
     BACKGROUND 
     The 3rd Generation Partnership Project (3GPP) is studying Non Terrestrial Network (NTN) in the Fifth-Generation mobile communications (5G) New Radio (NR). A research scope of 5G NTN mainly includes Spaceborne vehicles, such as Geostationary Earth Orbit Satellites (GEO), Medium Earth Orbit Satellites (MEO) and Low Earth Orbit Satellites (LEO), and airborne vehicle High Altitude Platforms (HAPS). A main feature of NTN lies in that its Round Trip Time (RTT) is relatively long, generally ranging from a few milliseconds to hundreds of milliseconds. One-way delays of different NTN deployment scenarios are shown in Table 1. An RTT is twice the one-way delay. Further, Table 1 also lists relevant parameters of terrestrial network cellular communication with a radius of 10 kilometers (km for short). 
     
       
         
           
               
               
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                   
                   
                   
                   
                 cellular 
               
               
                   
                 deployment- 
                 deployment- 
                 deployment- 
                 deployment- 
                 deployment- 
                 (radius of 
               
               
                   
                 D1 
                 D2 
                 D3 
                 D4 
                 D5 
                 10 km) 
               
               
                   
               
             
            
               
                 platform 
                 GEO located 
                 GEO 
                 Non GEO 
                 Non GEO 
                 airborne 
                   
               
               
                 track altitude 
                 at 
                 located at 
                 located 
                 located 
                 vehicle 
                   
               
               
                   
                 35786 km 
                 35786 km 
                 below 600 
                 below 600 
                 located 
                   
               
               
                   
                   
                   
                 km 
                 km 
                 above 20 
                   
               
               
                   
                   
                   
                   
                   
                 km 
                   
               
               
                 frequency 
                 Ka frequency 
                 S frequency 
                 S frequency 
                 Ka frequency 
                 S frequency 
                 S frequency 
               
               
                 band 
                 band 
                 band 
                 band 
                 band 
                 band (lower 
                 band 
               
               
                   
                   
                   
                   
                   
                 than 6 GHz) 
                   
               
               
                 maximum 
                 bent-pipe: 
                 272.37 
                 14.204 
                 14.204 
                 1.526 
                 0.03333 
               
               
                 one-way 
                 272.37 
                   
                   
                   
                   
                   
               
               
                 delay (ms) 
                 spaceborne 
                   
                   
                   
                   
                   
               
               
                   
                 gNB: 
                   
                   
                   
                   
                   
               
               
                   
                 135.28 
                   
                   
                   
                   
                   
               
               
                 maximum 
                 16 (satellite 
                 16 (satellite 
                 4.44 
                 4.44 
                 0.697 
                 0.00333 
               
               
                 delay 
                 covers from 
                 covers from 
                 (satellite 
                 (satellite 
                 (satellite 
                 (cell center 
               
               
                 edge to 
                 edge to  
                 edge to 
                 covers from 
                 covers from 
                 covers from 
                 to edge) 
               
               
                 difference 
                 center 
                 center 
                 edge to 
                 edge to 
                 edge to 
                 equals to 
               
               
                 (ms) 
                 point) 
                 point) 
                 center 
                 center  
                 center  
                 the 
               
               
                   
                   
                   
                 point) 
                 point) 
                 point) 
                 maximum 
               
               
                   
                   
                   
                   
                   
                   
                 delay 
               
               
                   
               
            
           
         
       
     
     Currently, it has been proposed to divide Timing Advance (TA) into a specific TA part for each User Equipment (UE) and a fixed TA part applicable to all UEs. The fixed TA part applicable to all UEs can be transmitted to the UE through system information. A similar solution may also be adopted for a time (abbreviated as K2) from a slot where an uplink resource carrying Uplink (UL) grant indication information is located to a slot where a resource of a UL grant is located. However, a disadvantage lies in that communication protocols need to be modified to add the fixed parts of TA and K2. For terrestrial network UEs, in order to support NTN communication, it is further required to implement relevant software and hardware updates (for example, increase variables and applications, check whether a value range of relevant variables will overflow, etc.), which may require additional maintenance of relevant software and hardware management branches and accordingly increase maintenance cost of the software and hardware. 
     Therefore, to realize NTN communication, how to determine UE parameters (for example, TA and/or K2) still needs further study. 
     SUMMARY 
     Embodiments of the present disclosure provide solutions for determining UE parameters such as TA and/or K2 to minimize modification to protocols and maintenance cost of software and hardware. 
     In an embodiment of the present disclosure, a UE parameter determination method is provided, including: determining a minimum round trip time between each UE in a cell and a satellite; determining frame information of a network-side uplink radio frame based on the minimum round trip time and frame information of a network-side downlink radio frame, where the minimum round trip time is a timing difference by which the network-side uplink radio frame lags behind the network-side downlink radio frame; and determining a UE parameter of each UE based on the network-side uplink radio frame and the network-side downlink radio frame, where the UE parameter includes at least one of TA or K2. 
     Optionally, determining the minimum round trip time between each UE in the cell and the satellite includes: determining the minimum round trip time between each UE in the cell and the satellite based on an altitude of the satellite. 
     Optionally, the minimum round trip time is counted by time slot, and is obtained by rounding down over time slot; or, the minimum round trip time is counted by subframe, and is obtained by rounding down over subframe. 
     Optionally, the minimum round trip time is transparent to each UE. 
     Optionally, the UE parameter is TA, and determining the UE parameter of each UE based on the network-side uplink radio frame and the network-side downlink radio frame includes: receiving an uplink signal from each UE; and calculating the TA of each UE based on the uplink signal, the network-side downlink radio frame and the network-side uplink radio frame. 
     Optionally, the UE parameter is K2, and determining the UE parameter of each UE based on the network-side uplink radio frame and the network-side downlink radio frame includes: when performing uplink scheduling for each UE, calculating the K2 of each UE based on the network-side uplink radio frame and the network-side downlink radio frame. 
     In an embodiment of the present disclosure, a UE parameter determination apparatus is provided, including: a first determining circuitry configured to determine a minimum round trip time between each UE in a cell and a satellite; a second determining circuitry configured to determine frame information of a network-side uplink radio frame based on the minimum round trip time and frame information of a network-side downlink radio frame, where the minimum round trip time is a timing difference by which the network-side uplink radio frame lags behind the network-side downlink radio frame; and a third determining circuitry configured to determine a UE parameter of each UE based on the network-side uplink radio frame and the network-side downlink radio frame, where the UE parameter includes at least one of TA or K2. 
     Optionally, the first determining circuitry includes: a determining sub-circuitry configured to determine the minimum round trip time between each UE in the cell and the satellite based on an altitude of the satellite. 
     Optionally, the minimum round trip time is counted by time slot, and is obtained by rounding down over time slot; or, the minimum round trip time is counted by subframe, and is obtained by rounding down over subframe. 
     Optionally, the minimum round trip time is transparent to each UE. 
     Optionally, the UE parameter is TA, and the third determining circuitry includes: a receiving sub-circuitry configured to receive an uplink signal from each UE; and a first calculating sub-circuitry configured to calculate the TA of each UE based on the uplink signal, the network-side downlink radio frame and the network-side uplink radio frame. 
     Optionally, the UE parameter is K2, and the third determining circuitry includes: a second calculating sub-circuitry configured to: when uplink scheduling is performed for each UE, calculate the K2 of each UE based on the network-side uplink radio frame and the network-side downlink radio frame. 
     In an embodiment of the present disclosure, a storage medium having computer instructions stored therein is provided, wherein when the computer instructions are executed, the above UE parameter determination method is performed. 
     In an embodiment of the present disclosure, a base station including a memory and a processor is provided, wherein the memory has computer instructions stored therein, and when the processor executes the computer instructions, the above UE parameter determination method is performed. 
     Embodiments of the present disclosure may provide following advantages. 
     In an embodiment of the present disclosure, a UE parameter determination method is provided, including: determining a minimum round trip time between each UE in a cell and a satellite; determining frame information of a network-side uplink radio frame based on the minimum round trip time and frame information of a network-side downlink radio frame, where the minimum round trip time is a timing difference by which the network-side uplink radio frame lags behind the network-side downlink radio frame; and determining a UE parameter of each UE based on the network-side uplink radio frame and the network-side downlink radio frame, where the UE parameter includes at least one of TA or K2. By the embodiment of the present disclosure, the minimum round trip time may be taken as the timing difference by which the network-side uplink radio frame lags behind the network-side downlink radio frame, so as to obtain the network-side uplink radio frame, and determine the value of TA and/or K2 based on the network-side uplink radio frame. Further, the UE may transmit and receive data based on the network-side uplink radio frame and the network-side downlink radio frame. An ultra-long round trip time in NTN is adjusted through a network to minimize modification of software and hardware of a terrestrial network UE, which may effectively avoid extra maintenance cost of software and hardware of the UE, i.e., NTN communication is supported. 
     Further, the minimum round trip time is transparent to each UE. By the embodiment of the present disclosure, the UE does not need to know the minimum round trip time, and the TA and K2 of the NTN UE may become relatively small by introducing the timing difference between the network-side uplink radio frame and the network-side downlink radio frame, which may minimize modification to related protocols and reduce maintenance cost of UE. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a scenario diagram of a UE parameter determination method in existing techniques; 
         FIG. 2  is a flow chart of a UE parameter determination method according to an embodiment; 
         FIG. 3  is a scenario diagram of a UE parameter determination method according to an embodiment; and 
         FIG. 4  is a structural diagram of a UE parameter determination apparatus according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     As described in the background, in the existing techniques, TA is divided into a specific TA part for each UE and a fixed TA part applicable to all UEs, and the fixed TA part is transmitted through system information. Similarly, a similar solution may also be adopted for a time (abbreviated as K2) from a slot where an uplink resource of UL grant indication is located to a slot when a UL grant is received. However, existing TA and K2 determination methods may cause the value of TA and K2 to greatly exceed a range of TA and K2 currently defined in the terrestrial network. 
     Taking a subcarrier interval of 15 kHz as an example, as shown in  FIG. 1 , a one-way transmission delay from a slot 0 of a frame of a network base station (for example, gNodeB (gNB)) to a time when a UE receives the frame is more than 5 ms, and an RTT between the gNB and the UE is more than 11 ms. 
     To achieve uplink timing synchronization, the gNB configures TA for the UE, so that the UE can complete uplink transmission in a desired time slot. Taking into account the RTT, the UE performs uplink data transmission more than 11 ms in advance (that is, TA compensates about 11 ms), so that an uplink signal of the UE can be aligned with an uplink frame of the network base station side when the uplink signal of the UE reaches the network base station. Further, a UL grant received by the UE in time slot 0 of frame 1 indicates that the UE can transmit data in time slot 4 of frame 2, and a value of K2 should be 14 time slots. 
     With the existing technical solutions, a minimum RTT between the gNB and the UE may be used as the fixed TA part and broadcast through system information, and the specific TA part may be notified to each UE by the gNB through a Timing Advance Command. The same processing applies to K2. Similarly, an interval of other subcarriers can be deduced by analogy and is not repeated here. It can be seen that the existing technical solutions require modification to protocols. Moreover, for the UE, in order to support NTN communication, it is further required to implement relevant software and hardware updates and maintain relevant variables, which increases maintenance cost of software and hardware. 
     In an embodiment of the present disclosure, a UE parameter determination method is provided, including: determining a minimum round trip time between each UE in a cell and a satellite; determining frame information of a network-side uplink radio frame based on the minimum round trip time and frame information of a network-side downlink radio frame, where the minimum round trip time is a timing difference by which the network-side uplink radio frame lags behind the network-side downlink radio frame; and determining a UE parameter of each UE based on the network-side uplink radio frame and the network-side downlink radio frame, where the UE parameter includes at least one of TA or K2. 
     By the embodiment of the present disclosure, the minimum round trip time may be taken as the timing difference by which the network-side uplink radio frame lags behind the network-side downlink radio frame, so as to obtain the network-side uplink radio frame, and determine the value of TA and/or K2 based on the network-side uplink radio frame. Further, the UE may transmit and receive data based on the network-side uplink radio frame and the network-side downlink radio frame. An ultra-long round trip time in NTN is adjusted through a network to minimize modification of software and hardware of a terrestrial network UE, which may effectively avoid extra maintenance cost of software and hardware of the UE, i.e., NTN communication is supported. 
     In order to clarify the objects, characteristics and advantages of the disclosure, embodiments of present disclosure will be described in detail in conjunction with accompanying drawings. 
       FIG. 2  is a flow chart of a UE parameter determination method according to an embodiment. 
     To ensure timing synchronization of a base station on a network side, the network may balance different transmission delays by adjusting uplink timing of each UE, so that uplink signals of each UE can reach the base station synchronously. For example, compared to UEs that are closer to the base station, UEs that are farther from the base station have a longer transmission time, thus, the UEs that are farther from the base station need to transmit uplink data in advance. A timing for transmitting in advance is calculated by the base station and notified to the UE. Specifically, the base station may configure TA for each UE and transmit it to the UE, and the UE adjusts an uplink data transmission timing based on the TA, thereby realizing timing synchronization on the base station side. In NTN communication, as an RTT between the base station and the UE is much larger than an RTT between a base station and a UE in terrestrial network communication, a value range of TA and/or K2 greatly exceeds the currently defined value range. 
     Therefore, an embodiment of the present disclosure provides a UE parameter determination method including S 101 , S 102  and S 103 . 
     In S 101 , a minimum round trip time between each UE in a cell and a satellite is determined. 
     In S 102 , frame information of a network-side uplink radio frame is determined based on the minimum round trip time and frame information of a network-side downlink radio frame, where the minimum round trip time is a timing difference by which the network-side uplink radio frame lags behind the network-side downlink radio frame. 
     In S 103 , a UE parameter of each UE is determined based on the network-side uplink radio frame and the network-side downlink radio frame, where the UE parameter includes at least one of TA or K2. Specifically, the UE parameter of each UE may be determined based on timing of the network-side uplink radio frame and timing of the network-side downlink radio frame. 
     In some embodiments, in S 101 , an NTN base station may determine a round trip time between each UE in the cell and the satellite, so as to obtain a minimum round trip time between the base station and the UE. 
     In some embodiments, the NTN base station may determine the minimum round trip time between each UE in the cell and the satellite based on an altitude of the satellite. For example, compare a round trip time between each UE and the satellite to obtain the minimum round trip time. Preferably, the NTN base station may assume that a particular UE is located at a terrestrial plane position closest to the satellite, and determine the round trip time between the particular UE and the satellite as the minimum round trip time. 
     In S 102 , the NTN base station may determine the frame information of the network-side uplink radio frame based on the minimum round trip time and the frame information of the network-side downlink radio frame. Those skilled in the art could understand that for terrestrial networks, the network does not distinguish network-side downlink radio frames and network-side uplink radio frames, and merely uses network-side radio frames as a reference for data transmission and reception. 
     In NTN communication, the base station may determine the network-side downlink radio frame and the network-side uplink radio frame for the network side. The frame information of the network-side downlink radio frame and the network-side uplink radio frame may be different. The network-side uplink radio frame lags behind the network-side downlink radio frame. 
     Specifically, uplink and downlink timings of the NTN base station are different, and the frame information of the network-side uplink radio frame may be determined based on the minimum round trip time and the frame information of the network-side downlink radio frame. The frame information may include one or more items of information such as frame number, time slot number, index information of subframe number, and the number of time slots included in the radio frame. Those skilled in the art understand that in actual applications, in the NTN base station, the frame information of the network-side uplink radio frame may be changed according to changes in specific applications, which is not described in detail here. 
     In some embodiments, the timing difference by which the network-side uplink radio frame lags behind the network-side downlink radio frame may be the minimum round trip time. After the frame information of the network-side downlink radio frame is determined, the minimum round trip time may be delayed to obtain the frame information of the network-side uplink radio frame. 
     In some embodiments, for the network side, the network-side uplink and downlink radio frames have different timings. For a particular moment, taking a time slot in the radio frame as an example, a frame number of the network-side downlink radio frame may be different from a frame number of the network-side uplink radio frame at that moment, and a time slot number in the network-side downlink radio frame may be also different from a time slot number in the network-side uplink radio frame. 
     The frame numbers and time slot numbers of the network-side uplink radio frame and the network-side downlink radio frame may be different. As shown in  FIG. 3 , taking 15 kHz as an example, each frame includes 10 time slots, from time slot 0 to time slot 9. gNB transmits a UL grant in time slot 0 of frame 1 to instruct a UE to perform uplink transmission in time slot 3 of frame 1, where K2 is 3 time slots, and is determined based on the network-side downlink radio frame and the network-side uplink radio frame. A network-side uplink radio frame timing lags behind a network-side downlink radio frame timing, where a lag time may be the minimum round trip time, or may be a result of rounding down over time slot. 
     Alternatively, for a particular moment, taking subframes in radio frames as an example, frame numbers of the network-side uplink radio frame and the network-side downlink radio frame at that moment may be different, and subframe numbers in the network-side downlink radio frame and in the network-side uplink radio frame may be also different. 
     Further, the minimum RTT may be counted in time slot. Generally, a duration of each time slot is 1 ms. Those skilled in the art could understand that the minimum RTT is obtained by rounding down over time slot to determine the network-side uplink radio frame. Alternatively, the minimum RTT may be counted in subframe. Those skilled in the art could understand that the minimum RTT is obtained by rounding down over subframe to determine the network-side uplink radio frame. 
     Further, the NTN base station may determine a TA value with a smaller time slot or subframe based on an existing calculation method and notify the TA value to the UE. For simplicity, a specific calculation process is not described here. 
     Further, in S 103 , an uplink and downlink timing difference of the NTN base station is transparent to the NTN UE. That is, the UE does not need to know that a difference exists between the uplink and downlink timing of the NTN base station. 
     Specifically, the NTN base station may use an uplink signal transmitted by the UE, the network-side uplink radio frame and the network-side downlink radio frame to calculate the TA. In some embodiments, the NTN base station may determine the value of TA by measuring a received random access preamble when the UE performs random access. When determining the TA of the UE, the NTN base station calculates it based on the network-side uplink radio frame, that is, when the NTN base station calculates the TA, the minimum round trip time (i.e., the timing difference by which the network-side uplink radio frame lags behind the network-side downlink radio frame) is deducted. Generally, after deducting the timing difference, the NTN base station may calculate the TA based on the measured random access preamble. In this way, the calculated TA value is relatively small, thereby minimizing the modification of existing protocols. 
     Those skilled in the art could understand that, for the NTN network, a step for determining K2 is similar to the step of determining TA. When performing UL scheduling on the UE, the NTN base station may deduct the minimum round trip time. Specifically, the NTN base station may calculate the value of K2 after deducting the timing difference by which the network-side uplink radio frame lags behind the network-side downlink radio frame, and a specific calculation process is not described here. 
     Afterward, the NTN base station may transmit the calculation result (i.e., the determined TA) to the UE through a Timing Advance Command. Generally, the NTN base station may transmit the calculation result to the UE through a timing advance command field of a random access response. 
     From above, with the technical solutions provided by the embodiments of the present disclosure, the UE parameters TA and/or K2 in the NTN network may be determined for the UE without modifying UE-side protocols Further, it is possible to minimize the modification of UE-side relevant protocols, which reduces maintenance cost of UE. 
       FIG. 4  is a structural diagram of a UE parameter determination apparatus according to an embodiment. The UE parameter determination apparatus  4  may be used to implement the technical solutions of the UE parameter determination method as shown in  FIG. 2  and  FIG. 3 , and be applied to the network side, for example, at an NTN base station (for example, 5G gNB). 
     Specifically, the UE parameter determination apparatus  4  may include a first determining circuitry  41 , a second determining circuitry  42  and a third determining circuitry  43 . 
     The first determining circuitry  41  is configured to determine a minimum round trip time between each UE in a cell and a satellite; the second determining circuitry  42  is configured to determine frame information of a network-side uplink radio frame based on the minimum round trip time and frame information of a network-side downlink radio frame, where the minimum round trip time is a timing difference by which the network-side uplink radio frame lags behind the network-side downlink radio frame; and the third determining circuitry  43  is configured to determine a UE parameter of each UE based on the network-side uplink radio frame and the network-side downlink radio frame, where the UE parameter includes at least one of TA or K2. 
     In some embodiments, the first determining circuitry  41  includes a determining sub-circuitry  411 . 
     The determining sub-circuitry  411  is configured to determine the minimum round trip time between each UE in the cell and the satellite based on an altitude of the satellite. 
     In some embodiments, the minimum round trip time is counted by time slot, and is obtained by rounding down over time slot; or, the minimum round trip time is counted by subframe, and is obtained by rounding down over subframe. 
     In some embodiments, the minimum round trip time is transparent to each UE. 
     In some embodiments, the UE parameter is TA, and the third determining circuitry  43  includes a receiving sub-circuitry  431  and a first calculating sub-circuitry  432 . 
     The receiving sub-circuitry  431  is configured to receive an uplink signal from each UE; and the first calculating sub-circuitry  432  is configured to calculate the TA of each UE based on the uplink signal, the network-side downlink radio frame and the network-side uplink radio frame. 
     Alternatively, the UE parameter is K2, and the third determining circuitry  43  includes a second calculating sub-circuitry  433 . The second calculating sub-circuitry  433  is configured to: when uplink scheduling is performed for each UE, calculate the K2 of each UE based on the network-side uplink radio frame and the network-side downlink radio frame. 
     More details of working principles and working modes of the UE parameter determination apparatus  4  can be found in the above descriptions of  FIG. 2  and  FIG. 3 , and are not described here. 
     In an embodiment of the present disclosure, a storage medium having computer instructions stored therein is provided, wherein when the computer instructions are executed, the above UE parameter determination method as shown in  FIG. 2  and  FIG. 3  is performed. In some embodiments, the storage medium may include a computer readable storage medium, such as a non-volatile memory or a non-transitory memory. The computer readable storage medium may include a Read Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk. 
     In an embodiment of the present disclosure, a base station including a memory and a processor is provided, wherein the memory has computer instructions stored therein, and when the processor executes the computer instructions, the above UE parameter determination method as shown in  FIG. 2  and  FIG. 3  is performed. In some embodiments, the base station may be a satellite base station. 
     Although the present disclosure has been disclosed above with reference to preferred embodiments thereof, it should be understood that the disclosure is presented by way of example only, and not limitation. Those skilled in the art can modify and vary the embodiments without departing from the spirit and scope of the present disclosure.