Base station equipment, systems, methods, and programs

Abstract

The present invention provides base station equipment, systems, methods, and programs that can suppress the degradation of communication quality. [Solution] The base station device comprises a transmitting unit that transmits a downlink signal to a wireless terminal, a receiving unit that receives an uplink signal transmitted from the wireless terminal, a first correction value calculation unit that calculates a first correction value based on the difference between the transmission parameters of the transmitted downlink signal and the reception parameters of the received uplink signal, and a correction unit that corrects the transmission parameters of the downlink signal to be transmitted to the wireless terminal based on the first correction value.

Description

[Technical Field]

[0001] This disclosure relates to base station equipment, systems, methods, and programs. [Background technology]

[0002] To achieve high capacity in mobile communication systems such as cellular systems, wireless communication using high-frequency bands such as millimeter waves and terahertz waves, which offer wide bandwidths, is becoming increasingly important. When using high-frequency bands for mobile communication, while the ability to utilize wide bandwidths enables high-capacity communication, there are challenges such as high propagation loss depending on the frequency and significant interference from obstacles due to the high directivity of radio waves that do not easily bend around other objects.

[0003] One way to solve the former problem of propagation loss is beamforming technology, which strengthens the received level of radio signals transmitted in the direction of the communication target by performing appropriate phase control on the radio signals transmitted from multiple antenna elements. By using beamforming technology, it is possible to compensate for the large propagation loss in the high frequency band. Another way to solve the latter problem of straight-line propagation is a distributed antenna system (DAS). By extending the base station antenna and distributing multiple antennas, the probability of line-of-sight communication between the antenna and the radio terminal being blocked is reduced.

[0004] Furthermore, in related macrocell systems, the large cell radius means that wireless terminals located at the cell edges are far from the base station, resulting in low received power and strong interference from adjacent cells, leading to a decline in communication quality. As one means of solving this problem, technologies that utilize and coordinate multiple base stations / antennas / cells / TRPs (Transmission Reception Points) / APs (Access Points) (hereinafter referred to as base stations) installed at relatively high density (e.g., Coordinated Multi-Point (CoMP), Multi-TRP (MTRP), Single Frequency Network (SFN), Distributed MIMO (Multiple Input Multiple Output)) have been put into practical use or are under consideration. For example, related technologies are known in Non-Patent Documents 1 and 2 and Patent Document 1. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2020 / 217588 [Non-patent literature]

[0006] [Non-Patent Document 1] Mostafa Khoshnevisan, Keeth Jayasinghe, Runhua Chen, Alexei Davydov, and Li Guo, "Enhanced Reliability and Capacity with Multi-TRP Transmission", IEEE Communications Standards Magazine, vol. 6, no. 1, pp. 13-19, March 2022, [Non-Patent Document 2] Huawei, HiSilicon, "Discussion on multi-TRP for high speed train in Rel-17", 3GPP TSG RAN WG1 Meeting #103-e / R1-2007590, November 2020,<URL https: / / www.3gpp.org / ftp / TSG_RAN / WG1_RL1 / TSGR1_103-e / Docs> [Overview of the project] [Problems that the invention aims to solve]

[0007] For example, in the case of in-vehicle terminals that perform high-capacity communication by being mounted on high-speed moving objects such as trains and automobiles, or in wireless environments where wireless terminals move at high speeds, the movement of wireless terminals between the communication areas of multiple base stations becomes relatively frequent. Therefore, joint transmission (JT) and dynamic point selection (DPS) technologies between multiple base stations become particularly important. Joint transmission (JT) technology includes any technology that enables simultaneous communication between multiple base stations and wireless terminals. Dynamic point selection (DPS) technology includes any technology that selects one base station from multiple base stations and enables communication between the selected base station and the wireless terminal.

[0008] In related technologies, for example, when multiple base stations and wireless terminals communicate simultaneously or with dynamic switching, there is a problem in that communication quality deteriorates due to differences in Doppler shift and propagation delay for each base station.

[0009] In view of these challenges, one of the objectives of this disclosure is to provide base station equipment, systems, methods, and programs that can suppress the deterioration of communication quality. [Means for solving the problem]

[0010] A base station device according to one aspect of the present disclosure includes: a transmitting unit that transmits a downlink signal to a wireless terminal; a receiving unit that receives an uplink signal transmitted from the wireless terminal; a first correction value calculation unit that calculates a first correction value based on the difference between the transmission parameters of the transmitted downlink signal and the reception parameters of the received uplink signal; and a correction unit that corrects the transmission parameters of the downlink signal to be transmitted to the wireless terminal based on the first correction value.

[0011] A system according to one aspect of the present disclosure is a system comprising a base station device and a wireless terminal, wherein the base station device comprises a transmitting unit that transmits a downlink signal to the wireless terminal, a receiving unit that receives an uplink signal transmitted from the wireless terminal, a first correction value calculation unit that calculates a first correction value based on the difference between the transmission parameters of the transmitted downlink signal and the reception parameters of the received uplink signal, and a correction unit that corrects the transmission parameters of the downlink signal to be transmitted to the wireless terminal based on the first correction value.

[0012] A method relating to one aspect of the present disclosure is a method for a base station device, comprising: transmitting a downlink signal to a wireless terminal; receiving an uplink signal transmitted from the wireless terminal; calculating a first correction value based on the difference between the transmission parameters of the transmitted downlink signal and the reception parameters of the received uplink signal; and correcting the transmission parameters of the downlink signal to be transmitted to the wireless terminal based on the first correction value.

[0013] A program according to one aspect of the present disclosure is a program for causing a computer to execute a method for a base station device, the method comprising: transmitting a downlink signal to a wireless terminal; receiving an uplink signal transmitted from the wireless terminal; calculating a first correction value based on the difference between the transmission parameters of the transmitted downlink signal and the reception parameters of the received uplink signal; and correcting the transmission parameters of the downlink signal to be transmitted to the wireless terminal based on the first correction value. [Effects of the Invention]

[0014] According to this disclosure, it is possible to suppress the deterioration of communication quality. [Brief explanation of the drawing]

[0015] [Figure 1] This is an explanatory diagram illustrating the changes in Doppler shift and propagation delay during base station switching. [Figure 2] This is an explanatory diagram for explaining the processing of the NW-based Pre-compensation method. [Figure 3] This is a sequence diagram showing the processing flow of the NW-based Pre-compensation method. [Figure 4] This is a schematic diagram illustrating the movement of wireless terminals between base station coverage areas. [Figure 5] This graph shows the change in the received frequency of a wireless terminal as it moves between base station coverage areas. [Figure 6] This is a configuration diagram showing some examples of the configuration of wireless communication systems according to several embodiments. [Figure 7] This is a configuration diagram showing an example of the configuration of a first base station device according to several embodiments. [Figure 8] This is a configuration diagram showing an example of the configuration of a second base station device according to several embodiments. [Figure 9] This is a configuration diagram showing an example of the arrangement of multiple devices that constitute a base station device according to several embodiments. [Figure 10] This is a configuration diagram showing an example of the arrangement of multiple devices that constitute a base station device according to several embodiments. [Figure 11] Sequence diagrams illustrating examples of operation in several embodiments of wireless communication systems. [Figure 12] This is a configuration diagram showing some examples of the configuration of wireless communication systems according to several embodiments. [Figure 13] This is a configuration diagram showing some examples of the configuration of a base station device according to several embodiments. [Figure 14] This diagram shows an example configuration of a signal processing unit according to several embodiments. [Figure 15] This flowchart shows examples of operation of a base station device according to several embodiments. [Figure 16] This is a configuration diagram showing some examples of the configuration of wireless communication systems according to several embodiments. [Figure 17] This flowchart shows examples of operation of a base station device according to several embodiments. [Figure 18] This is a configuration diagram showing some examples of the configuration of a base station device according to several embodiments. [Figure 19] This is a configuration diagram showing some examples of the configuration of wireless communication systems according to several embodiments. [Figure 20] This diagram shows an example configuration of a signal processing unit according to several embodiments. [Figure 21] This diagram shows an example configuration of a signal processing unit according to several embodiments. [Figure 22] This diagram shows some configuration examples of a signal correction unit according to several embodiments. [Figure 23] This diagram shows some configuration examples of a signal correction unit according to several embodiments. [Figure 24] This is a configuration diagram showing an example of the hardware configuration of a base station device according to several embodiments. [Modes for carrying out the invention]

[0016] The embodiments will be described below with reference to the drawings. In each drawing, the same elements are denoted by the same reference numerals, and redundant explanations are omitted where necessary. The arrows shown in each drawing are illustrative for illustrative purposes only and do not limit the type or direction of the signal.

[0017] (Consideration of related technologies) When multiple base stations with different physical locations communicate with a wireless terminal, the wireless terminal is affected by different Doppler shifts and propagation delays for each base station. If the Doppler shift and propagation delay differ significantly between base stations, communication quality may deteriorate during JT or DPS operation due to inter-subcarrier / inter-symbol interference in Orthogonal Frequency Division Multiplexing (OFDM), as well as phase rotation in the frequency / time direction of the channel.

[0018] Using DPS as an example, Figure 1 shows that when a wireless terminal switches from base station #2 to base station #1, the Doppler shift is f d1 from f d2 Next, an example is shown where the propagation delay changes from τ1 to τ2. In order to stabilize communication quality when switching antennas, it is necessary to compensate for Doppler shift and abrupt changes in propagation delay.

[0019] The same problem exists with JT. In JT, the signals received by a wireless terminal from each base station antenna are subject to different Doppler shifts and propagation delays. It is difficult for a wireless terminal to simultaneously receive and compensate for the different Doppler shifts and propagation delays of multiple base station antennas, which can significantly degrade the communication quality of JT.

[0020] In the 3GPP (Third Generation Partnership Project), two methods were discussed to address the issue of different Doppler shifts occurring for each base station in Multi-TRP technology (see Non-Patent Document 1).

[0021] The first is the UE-based Compensation method. The wireless terminal measures the Doppler shift of multiple antennas using the downlink reference signal, and performs Automatic Frequency Control (AFC) based on the measured values according to the antenna switching. The antenna switching is notified to the wireless terminal by Transmission Configuration Indication (TCI).

[0022] The second is the NW-based Pre-compensation method. The base station measures the Doppler shift using the uplink reference signal, and the base station pre-compensates the Doppler shift based on the measured values and transmits a signal to the wireless terminal. Fig. 2 shows an explanatory diagram of the processing of the NW-based Pre-compensation method. At this time, if the carrier frequency of the wireless communication system is f c and the base station that establishes synchronization with the wireless terminal is Base Station #1, Base Station #1 transmits a signal at frequency f c as in other related technologies, and the wireless terminal receives a signal at frequency f c +f d1 that has undergone Doppler shift. Here, f d1 is the Doppler shift between Base Station #1 and the wireless terminal. Base Station #2 transmits a signal with its frequency corrected to f c +f d1 such that the received signal frequency of the wireless terminal becomes f c +f d1 -f d2 . Through the above processing, when joint transmission (JT) is performed among multiple base stations, the received frequencies of the signals of each of the multiple base stations at the wireless terminal are constant, so that a degradation in communication quality can be suppressed.

[0023] Non-Patent Document 2 discloses the processing flow of frequency pre-compensation in the aforementioned NW-based Pre-compensation method. Fig. 3 shows the processing flow cited from Non-Patent Document 2.

[0024] In the above technology, base station #1 (corresponding to "TRP1" in Figure 3), which establishes synchronization with the wireless terminal (corresponding to "UE" in Figure 3), performs synchronization as with other related technologies without any special prior compensation. At this time, the transmission and reception frequency f of the wireless terminal UE The carrier frequency is f c The Doppler shift of base station #1 is f d1 Therefore, f UE =f c +f d1 This is the result.

[0025] Base station #2 (corresponding to "TRP2" in Figure 3) is set to receive wireless terminals at a frequency of f UE =f c +f d1 The transmission frequency is pre-compensated to achieve this. Specifically, the Doppler shift between base station #2 and the wireless terminal is f d2 In this case, the uplink reference signal transmitted by the wireless terminal after synchronization with base station #1, and the received frequency f at base station #2 TRP2 =f UE +f d2 =f c +f d1 +f d2 Therefore, the receiving frequency f at base station #1 TRP1 =f UE +f d1 The value obtained by subtracting this is the f value corrected for the carrier frequency. c -(f TRP2 -f TRP1 )=f c +f d1 -f d2 It transmits using that as the transmission frequency.

[0026] Hereafter, a base station that establishes synchronization with a wireless terminal will be referred to as a synchronization base station. In the method of Non-Patent Document 2, the transmission and reception frequency f of the wireless terminal UE This depends on the Doppler shift between the wireless terminal and the synchronous base station. For example, if the synchronous base station is switched from base station #1 to base station #2 due to the movement of the wireless terminal, the transmit and receive frequency of the wireless terminal will be f UE =f c +f d1 From, f UE =f c +fd2 It needs to be changed to this.

[0027] Figure 4 shows a schematic diagram of a wireless terminal moving from the coverage area of ​​base station #1 to the coverage area of ​​base station #2. Figure 5 shows the changes in the received frequencies at base stations #1 and #2, and the actual received frequency of the wireless terminal, when the wireless terminal moves as shown in Figure 4, without any frequency compensation.

[0028] As shown in Figure 5, when a wireless terminal switches its synchronous base station from base station #1 to base station #2, it may be strongly affected by Doppler shift and communication quality may deteriorate until synchronization with base station #2 is established and the wireless terminal's transmit / receive frequency tracks the receive frequency at base station #2. This is because the wireless terminal's transmit / receive frequency depends on the Doppler shift between it and the synchronous base station, and this becomes particularly noticeable when the Doppler shifts between base stations differ significantly during the synchronous base station switch.

[0029] Thus, in the related NW-based pre-compensation scheme, the transmission and reception frequencies of wireless terminals depend on the Doppler shift between them and the synchronous base station. This leads to a problem where communication quality deteriorates due to the abrupt change in the Doppler shift when the synchronous base station is switched. Similarly, problems arise when each base station has a different propagation delay.

[0030] Furthermore, Patent Document 1 describes a method in which each of multiple base stations performs pre-compensation for the Doppler shift of each wireless terminal. However, Patent Document 1 does not describe a specific method for determining the frequency to be compensated for at each base station, nor does it consider the case where the wireless terminal performs AFC operation.

[0031] (First embodiment) Next, a first embodiment will be described. In the first embodiment, an overview of several embodiments will be provided.

[0032] Figure 6 shows some configuration examples of wireless communication systems according to several embodiments. Wireless communication system 1 may be a system defined by, for example, 5G (5th Generation), NR, or LTE (Long Term Evolution) standards, but is not limited to these systems. For example, it may be a system defined by a next-generation standard including Beyond 5G (6G), or a system defined by a standard of another generation.

[0033] In the example shown in Figure 6, the wireless communication system 1 includes one or more base station devices 10 (10a and 10b in this example) and a wireless terminal 20. In the case of multiple base station devices 10, simultaneous communication or dynamic switching communication is performed with the wireless terminal 20.

[0034] For example, base station device 10a is referred to as the first base station device, and base station device 10b is referred to as the second base station device, but either base station device may be the first or the second base station device. For example, either base station device 10a or base station device 10b may simply be referred to as the base station device, and the other as the other base station device. Also, the number of base station devices 10 and wireless terminals 20 in Figure 6 is just an example and is not limited to this.

[0035] The first base station device 10a and the second base station device 10b provide the base station functions necessary for the wireless terminal 20 to use wireless communication services. For example, the first base station device 10a and the second base station device 10b may be gNB (next Generation Node B) or eNB (evolved Node B), etc.

[0036] The wireless terminal 20 communicates wirelessly with the first base station device 10a and the second base station device 10b, respectively. For example, the wireless terminal 20 may be a terminal device such as a UE (User Equipment), or it may be a relay device that relays wireless communication with other terminals. Downlink signals and uplink signals are transmitted and received between the first base station device 10a and the second base station device 10b and the wireless terminal 20. The wireless terminal 20 uses an AFC (Automatic Frequency Control) function to synchronize its frequency with the received downlink signal and transmits an uplink signal at the synchronized frequency. The wireless terminal 20 also uses a timing synchronization function to synchronize its timing with the received downlink signal and transmits an uplink signal at the synchronized timing.

[0037] Figure 7 shows an example configuration of a first base station device 10a in a wireless communication system according to several embodiments. For example, the first base station device 10a is a base station that corrects parameters by a first means (first method). For example, the parameter is frequency when compensating for Doppler shift between the base station device and the wireless terminal, and timing offset when compensating for propagation delay between the base station device and the wireless terminal. Here, the frequency or timing correction may be analog correction that corrects the frequency or timing of the wireless signal in the analog domain, or it may be digital correction that corrects the effect of the frequency or timing deviation in the digital domain.

[0038] In the example shown in Figure 7, the first base station device 10a includes a transmitting unit 11, a receiving unit 12, a first correction value calculation unit 13a, and a correction unit 14.

[0039] The transmitting unit 11 transmits a downlink signal to the wireless terminal 20. The transmitting unit 11 transmits a downlink signal with predetermined transmission parameters set. For example, the transmission parameters to be set may be the target parameters when the wireless terminal 20 receives the downlink signal.

[0040] The receiving unit 12 receives the uplink signal transmitted from the wireless terminal 20. For example, the receiving unit 12 receives the uplink signal transmitted from the wireless terminal 20 after the wireless terminal 20 has synchronized with the downlink signal.

[0041] The first correction value calculation unit 13a calculates a first correction value for correcting the downlink signal using the first means. In the case of the first means, the first correction value calculation unit 13a calculates the first correction value based on the difference between the transmission parameters of the downlink signal transmitted by the transmission unit 11 and the reception parameters of the uplink signal received by the reception unit 12. The transmission parameters of the transmitted downlink signal are the parameters of the downlink signal when transmitted from the transmission unit 11. The reception parameters of the received uplink signal are the parameters of the uplink signal when received by the reception unit 12, and may also be parameters obtained by measuring the received uplink signal. The first correction value calculation unit 13a may also use a value obtained by multiplying the difference between the transmission parameters at the time of transmission and the reception parameters at the time of reception by a coefficient as the first correction value. For example, the first correction value may be obtained by multiplying the difference between the transmission parameters at the time of transmission and the reception parameters at the time of reception by 1 / 2.

[0042] The correction unit 14 corrects the transmission parameters of the downlink signal to be transmitted to the wireless terminal 20 based on the first correction value it has calculated. For example, the correction unit 14 may determine the transmission parameters to be used for correction based on the first correction value it has calculated, and then correct the downlink signal to be transmitted based on the determined transmission parameters. The correction unit 14 may also determine the transmission parameters based on the target parameters at the time of reception of the downlink signal at the wireless terminal 20 and the first correction value. For example, it may determine the transmission parameters as the value obtained by subtracting the first correction value from the target parameters.

[0043] The correction unit 14 may correct not only the transmission parameters of the downlink signal transmitted to the wireless terminal 20, but also the reception parameters of the uplink signal received from the wireless terminal 20. For example, the correction unit 14 may correct the reception parameters of the uplink signal received from the wireless terminal 20 based on a first correction value. The correction unit 14 may also determine the reception parameters based on the target parameters at the time of reception of the downlink signal in the wireless terminal 20 and the first correction value. For example, the value obtained by adding the first correction value to the target parameters may be determined as the reception parameters.

[0044] Figure 8 shows an example configuration of a second base station device 10b in a wireless communication system according to several embodiments. For example, the second base station device 10b is a base station that corrects parameters by a second means (second method).

[0045] In the example shown in Figure 8, the second base station device 10b includes a transmitting unit 11, a receiving unit 12, a correction unit 14, and a second correction value calculation unit 13b, similar to the example in Figure 7.

[0046] The second correction value calculation unit 13b calculates a second correction value for correcting the downlink signal using a second means. In the case of the second means, the second correction value calculation unit 13b calculates the second correction value based on the difference between the target parameter at the time of reception of the downlink signal at the wireless terminal 20 and the reception parameter of the uplink signal received by the receiving unit 12. The target parameter may be shared between the first base station device 10a and the second base station device 10b, or it may be a predetermined value. The reception parameter of the received uplink signal is the parameter of the uplink signal at the time of reception by the receiving unit 12, or it may be a parameter obtained by measuring the received uplink signal. The second correction value calculation unit 13b may use a value obtained by multiplying the difference between the target parameter and the reception parameter at the time of reception by a coefficient as the second correction value. The correction unit 14 corrects the transmission parameter of the downlink signal to be transmitted to the wireless terminal 20 based on the calculated second correction value. The correction unit 14 may also correct the reception parameter of the uplink signal received from the wireless terminal 20 based on the calculated second correction value.

[0047] The base station device 10 may also include a first correction value calculation unit 13a and a second correction value calculation unit 13b, and calculate either the first correction value or the second correction value by either the first or second means. For example, it may include a selection unit that selects whether to calculate the first correction value by the first means or the second correction value by the second means.

[0048] Furthermore, each function of the base station device 10 may be composed of one device or multiple devices. For example, the base station device 10 may be functionally divided into control devices (e.g., CU (Central Unit), DU (Distributed Unit)), radio devices (e.g., RU (Radio Unit)), etc. Also, multiple base station devices may each have a different physical cell ID, or multiple base station devices may have the same cell ID.

[0049] Figures 9 and 10 show examples of the arrangement of each device when the functions of the base station device are divided into a control device and a radio device. For example, as shown in Figure 9, the base station device 10 may be configured such that multiple radio devices 32 are connected to one control device 31 (e.g., distributed MIMO, SFN). That is, simultaneous communication or dynamic switching communication may be performed between multiple radio devices 32 and a radio terminal 20. In this case, each radio device 32 may have the functions of base station device 10a or 10b.

[0050] Furthermore, as shown in Figure 10, the base station device 10 may be configured such that one control device 31 is connected to one wireless device 32. In other words, simultaneous communication or dynamic switching communication may be performed between multiple base station devices 10, each including a control device 31 and a wireless device 32, and the wireless terminal 20. In this case, the base station device 10 including the control device 31 and the wireless device 32 may have the functions of base station device 10a or 10b.

[0051] Figure 11 shows an example of operation in a wireless communication system 1 according to several embodiments. In the example in Figure 11, the target parameter at reception in the wireless terminal 20 is p UESteps (S1-1) to (S1-4) are performed by the first means (first base station device 10a), and steps (S2-1) to (S2-3) are performed by the second means (second base station device 10b).

[0052] First, in step (S1-1), the first base station device 10a sets the first transmission parameter p as an initial value. TX1 Target parameter p UE Set the first transmission parameter p TX1 It transmits the first downlink reference signal.

[0053] Next, in step (S1-2), the first base station device 10a receives the uplink reference signal transmitted from the radio terminal 20 after the radio terminal 20 has received and synchronized with the first downlink reference signal, and the first received parameter p of the received uplink reference signal RX1 Measure.

[0054] For example, if the parameter is frequency, p UE Assuming =40GHz and p1=0.1GHz, the frequency of the downlink reference signal received by the wireless terminal 20 is p UE +p1 = 40.1GHz, and the synchronized wireless terminal 20 is p UE +p1=40.1GHz uplink signal is transmitted. Then the frequency of the uplink signal received by the first base station device 10a is p RX1 =p UE +2p1 = 40.2GHz.

[0055] Next, in step (S1-3), the first base station device 10a, as an example, calculates the difference Δp between the first receiving parameter and the first transmitting parameter of the first downlink reference signal. RX / TX =p RX1 -p TX1 Half of the amount Δp1 = Δp TX / RX We calculate / 2 as the first difference (correction value).

[0056] Next, in step (S1-4), the first base station device 10a sets the target parameter pUE For this, the parameter p corrected for the first difference is TX1 =p UE -Δp1 is used as the first transmission parameter to transmit a second downlink reference signal, or any downlink signal.

[0057] In the above frequency example, the correction value Δp1 = (p RX1 -p TX1 ) / 2 = (40.2 - 40) / 2 = 0.1 GHz, and the first transmission parameter p TX1 =p UE -Δp1 = 40 - 0.1 = 39.9 GHz. When the first base station device 10a transmits a downlink reference signal at 39.9 GHz, the frequency of the downlink reference signal received by the wireless terminal 20 is p UE =40GHz, and the synchronized wireless terminal 20 is p UE = Transmits an uplink signal at 40GHz.

[0058] Furthermore, in step (S2-1), the second base station device 10b receives the uplink reference signal transmitted by the wireless terminal 20 synchronized in step (S1-2) of the first means, and the second received parameter p of the received uplink reference signal RX2 Measure.

[0059] In the above frequency example, if p2 = -0.2 GHz, the synchronized wireless terminal 20 will be p UE When an uplink signal of 40 GHz is transmitted, the frequency of the uplink signal received by the second base station device 10b is p RX2 =p UE +p2 = 39.8GHz.

[0060] Next, in step (S2-2), the second base station device 10b calculates the second difference (correction value) Δp2 = p between the second received parameter and the target parameter. RX2 -p UE Calculate.

[0061] Next, in step (S2-3), the second base station device 10b corrects the second difference with respect to the target parameter and sets a second transmission parameter p TX2 =p UE -Δp2 transmits an arbitrary downlink signal.

[0062] In the above frequency example, the correction value Δp2 = p RX2 -p UE =39.8-40=-0.2GHz, and the second transmission parameter p TX2 =p UE -Δp2 = 40 + 0.2 = 40.2 GHz. When the second base station device 10b transmits a downlink reference signal at 40.2 GHz, the frequency of the downlink reference signal received by the wireless terminal 20 is p UE This results in a frequency of 40GHz. As a result, the frequency of the signal received by the wireless terminal 20 from the first base station device 10a and the frequency of the signal received from the second base station device 10b become the same.

[0063] As described above, when AFC or timing synchronization is implemented in a wireless terminal, the transmit / receive frequency and transmit / receive timing of the wireless terminal are determined by the downlink reference signal received by the wireless terminal. In this case, the uplink reference signal transmitted by the wireless terminal and received by the base station is subject to a Doppler shift and propagation delay equal to the sum of the downlink and uplink. In particular, if the downlink and uplink Doppler shifts and propagation delays are equal or approximately equal, the uplink reference signal received by the base station is subject to a Doppler shift and propagation delay approximately twice that of the transmitted downlink reference signal (see, for example, the sequence chart in Figure 11).

[0064] For example, by estimating half the difference in frequency and timing offset between the transmitted downlink reference signal and the received uplink reference signal—that is, approximately estimating the downlink Doppler shift and propagation delay—and correcting and transmitting the downlink signal, it is possible to maintain a constant receiving frequency and timing offset for the wireless terminal. In particular, even when AFC and timing synchronization are implemented in the wireless terminal, the receiving frequency and timing offset of the wireless terminal can be maintained constant. Therefore, it is possible to suppress the deterioration of communication quality when performing simultaneous communication or dynamic switching communication.

[0065] Furthermore, if the Doppler shift and propagation delay of the downlink and uplink differ, the receiving frequency and timing offset of the wireless terminal can be kept constant by obtaining a correction value for the downlink signal by multiplying the difference in frequency and timing offset between the transmitted downlink reference signal and the received uplink reference signal by a coefficient. In this embodiment, it is assumed that the uplink reference signal transmitted from the wireless terminal is transmitted after the wireless terminal receives the first or second downlink reference signal and is fully synchronized, but it is not necessarily required that the wireless terminal is fully synchronized, and the uplink reference signal may be transmitted before it is fully synchronized. If it is not fully synchronized, in a single process, the receiving parameters of the wireless terminal will be p UE Although it does not converge to p, by repeatedly performing steps (S1-2) to (S1-4), the reception parameters of the wireless terminal can be adjusted to p UE It is possible to converge to this.

[0066] In the following embodiments, a specific example of the first embodiment will be described.

[0067] (Second Embodiment) Next, a second embodiment will be described. In the second embodiment, a case will be described in which a base station device establishes synchronization with a wireless terminal and communicates using the first means. As an example, the operation of a single base station device that synchronizes and communicates with a wireless terminal will be described. However, multiple base station devices may synchronize and communicate with a wireless terminal using the same configuration and operation as the base station device in this embodiment. In other words, multiple base station devices may use the first means.

[0068] Figure 12 shows some configuration examples of wireless communication systems according to several embodiments. In the example in Figure 12, the wireless communication system 2 includes a base station device 100 and a wireless terminal 200. For example, the base station device 100 corresponds to the first base station device 10a in Figure 6, and the wireless terminal 200 corresponds to the wireless terminal 20 in Figure 6.

[0069] The base station device 100 is a network node that constitutes the radio access network (RAN) in the wireless communication system 2. The base station device 100 is connected to the core network and provides a cell for wireless communication with the wireless terminal 200. The base station device 100 may be, for example, a gNB or eNB, or other base stations (NB; Node B, etc.). The base station device 100 may consist of multiple functions. The base station device 100, which includes multiple functions, may be implemented by one device or by multiple devices. The multiple devices that make up the base station device 100 may be located in the same location or in different locations. The devices that make up the base station device 100 may include physical devices (computers) or virtual machines that operate on a virtualization infrastructure. For example, the base station device 100 may constitute a vRAN (virtual RAN) or an O-RAN (Open RAN). As described above, the base station device 100 may include any number of RUs, DUs, and CUs.

[0070] The wireless terminal 200 is a terminal device that accesses a wireless access network including the base station equipment 100 and communicates with a data network, etc., via the base station equipment 100 and the core network. The wireless terminal 200 communicates wirelessly with the base station equipment 100 in the cell provided by the base station equipment 100. For example, the wireless terminal 200 may be an UE, a mobile phone, a smartphone, a tablet terminal, an IoT (Internet of Things) terminal, etc. The wireless terminal 200 may also be mounted on a mobile device such as an automobile, train, robot, or drone.

[0071] Figure 13 shows an example configuration of a base station device 100 according to several embodiments. In this embodiment, the base station device 100 calculates a correction value using a first means and corrects the uplink signal and / or downlink signal.

[0072] In the example shown in Figure 13, the base station device 100 includes one or more transmitting / receiving units 110, a signal processing unit 120, a correction value calculation unit 130, and a parameter determination unit 140. The signal processing unit 120 further includes a received parameter measurement unit 121 and a signal correction unit 122.

[0073] The transmitting / receiving unit 110 transmits and receives downlink signals and uplink signals with the wireless terminal 200. The transmitting / receiving unit 110 includes an analog-to-digital converter, an amplifier, an antenna element, etc. In the downlink, the transmitting / receiving unit 110 processes the signal transmitted from the signal processing unit 120 to be transmitted as radio waves, and in the uplink, it processes the signal transmitted from the wireless terminal 200 to be received.

[0074] The signal processing unit 120 processes the uplink signal received by the transmitting / receiving unit 110 and the downlink signal transmitted by the transmitting / receiving unit 110. The signal processing unit 120 includes a received parameter measurement unit 121 and a signal correction unit 122.

[0075] Figure 14 shows a detailed configuration of the signal processing unit 120 according to several embodiments, and an example of the processing flow for uplink and downlink signals. For the purpose of explaining the processing, Figure 14 shows a configuration that includes a demodulation unit 123, a modulation unit 124, and an FFT / IFFT (Fast Fourier Transform / Inverse Fast Fourier Transform) 125 in addition to the reception parameter measurement unit 121 and the signal correction unit 122.

[0076] The receiving parameter measurement unit 121 measures the received parameter p based on the uplink signal from the wireless terminal 200 received by the transmitting / receiving unit 110. RX meas The reception parameters are measured. If the base station device 100 has multiple transceiver units 110, the reception parameters may be measured for each transceiver unit 110, or they may be measured collectively across multiple transceiver units 110. The uplink signal may be, for example, an SRS (Sounding Reference Signal) or a DMRS (Demodulation Reference Signal). The reception parameters may, as an example, be the reception frequency and / or reception timing of the signal. For example, the reception frequency may be measured based on the time correlation of the received signal, and the reception timing may be measured based on the frequency correlation of the received signal. The reception parameter measurement unit 121 may also have a function to infer reception parameters. For example, future reception parameters may be inferred based on reception parameters measured in the past. The arrangement of the reception parameter measurement unit 121 in the signal processing unit 120 may be appropriately changed depending on the measurement target. The measured or inferred reception parameters are notified to the correction value calculation unit 130.

[0077] The signal correction unit 122 (122a and / or 122b) corrects the uplink signal and / or downlink signal based on the parameters notified by the parameter determination unit 140. For example, the signal correction unit 122a corrects the uplink signal based on the received parameters, and the signal correction unit 122b corrects the downlink signal based on the transmitted parameters.

[0078] The FFT / IFFT125 in Figure 14 represents, for example, OFDM modulation processing in an OFDM system, where the signal is converted between the time domain and the frequency domain by the FFT / IFFT125. On the left side of the FFT / IFFT125 in Figure 14 (demodulation and modulation side), the signal is a frequency domain signal, while on the right side (transceiver side), the signal is a time domain signal.

[0079] However, the positional relationship between the signal correction unit 122 and the FFT / IFFT 125 is not limited to that shown in Figure 14, and the positional relationship may be appropriately changed depending on the parameters corrected by the signal correction unit 122 and the correction method. For example, when the signal correction unit 122 digitally corrects the frequency of the transmitted and received signals, correction to the frequency domain signal requires a complex convolution operation, but correction to the time domain signal can be done with a simple multiplication operation that corrects the phase of the signal at each time step. Therefore, the signal correction unit 122 may be located to the right of the FFT / IFFT 125. As another example, when the signal correction unit 122 digitally corrects the transmission and reception timing of the transmitted and received signals, correction to the time domain signal requires a complex convolution operation, but correction to the frequency domain signal can be done with a simple multiplication operation that corrects the phase of the signal at each frequency bin. Therefore, the signal correction unit 122 may be located to the left of the FFT / IFFT 125, as shown in Figure 14.

[0080] The corrected signals may include, for example, SSB (Synchronization Signal Block), CSI-RS (Channel State Information Reference Signal), TRS (Tracking Reference Signal), DMRS, PTRS (Phase Tracking Reference Signal), PDCCH (Physical Downlink Control Channel), PDSCH (Physical Downlink Shared Channel), SRS, PUCCH (Physical Uplink Control Channel), PUSCH (Physical Uplink Shared Channel), etc.

[0081] The demodulation unit 123 performs demodulation processing on the uplink signal after correction by the signal correction unit 122a. For example, in the case of MIMO transmission, the demodulation unit 123 may perform MIMO equalization processing.

[0082] The modulation unit 124 performs modulation processing on the downlink signal to be transmitted. For example, in the case of MIMO transmission, the modulation unit 124 may perform precoding processing. The signal modulated by the modulation unit 124 is corrected by the signal correction unit 122b.

[0083] For example, the correction value calculation unit 130 corresponds to the first correction value calculation unit 13a in FIG. 7. The correction value calculation unit 130 calculates a correction value Δp by the first means and notifies the calculated correction value Δp to the parameter determination unit 140.

[0084] In the first means, the correction value calculation unit 130 uses the measured reception parameter p RX meas notified by the reception parameter measurement unit 121 and the downlink transmission parameter p TX determined by the parameter determination unit 140 in the past to calculate the correction value Δp based on the difference therebetween. A storage unit that stores the downlink transmission parameter p TX determined (transmitted) in the past may be provided, and the stored transmission parameter p TX may be referred to. The downlink transmission parameter p TX determined in the past is the downlink transmission parameter p TX of the downlink signal transmitted before the measured (received) uplink signal. The downlink transmission parameter p TX determined in the past is, for example, the target parameter p UE but may be other values. However, when the base station device 100 includes a plurality of transmission / reception units 110 and a plurality of measured reception parameters are notified by the reception parameter measurement unit 121, the correction value may be calculated for each measured reception parameter or may be calculated collectively for the plurality of measured reception parameters.

[0085] In the first means, the correction value may be calculated as in the following calculation example.

[0086] <Example 1 of correction value calculation for the first means> The correction value calculation unit 130 may calculate, as in the following formula (1), the half of the difference between the measurement reception parameter p RX meas and the transmission parameter p TX as the correction value Δp. Δp=(p RX meas -p TX ) / 2 ···(1)

[0087] Since the above difference corresponds to the sum of the parameter variations in the downlink and the parameter variations in the uplink when the wireless terminal 200 performs AFC or transmission / reception timing control, when the parameter variations in the downlink and the uplink are equivalent, in calculation example 1, a value corresponding to the parameter variation in either the downlink or the uplink can be calculated as the correction value.

[0088] <Example 2 of correction value calculation for the first means> The correction value calculation unit 130 may calculate, as in the following formula (2), the value obtained by multiplying an arbitrary coefficient k by the difference between the measurement reception parameter p RX meas and the transmission parameter p TX as the correction value Δp. Δp=(p RX meas -p TX )·k ···(2)

[0089] Calculation example 2 is a generalized example of calculation example 1. When the parameter variations in the downlink and the uplink are different, by determining the coefficient k according to the difference in the parameter variations, a value corresponding to the parameter variation in either the downlink or the uplink can be calculated as the correction value. For example, multiplying the above difference by the coefficient k down for the downlink to calculate the correction value Δp down for the transmission signal, and multiplying the above difference by the coefficient k up for the uplink to calculate the correction value Δp for the reception signalup You may calculate this.

[0090] The parameter determination unit 140 determines the transmission parameter p of the downlink based on the correction value notified by the correction value calculation unit 130. TX or / and the uplink receiving parameter p RX The parameter is determined. However, if the base station device 100 has multiple transmitting and receiving units 110 and multiple correction values ​​are notified by the correction value calculation unit 130, the parameter may be determined for each correction value, or it may be determined collectively for multiple correction values. The parameter determination unit 140 determines the transmission parameter p of the downlink that has been determined. TX or / and the uplink receiving parameter p RX This information is sent to the signal correction unit 122.

[0091] For example, the parameter determination unit 140 determines the transmission parameter p TX target parameter p UE Alternatively, it may be determined by the following equation (3) based on the correction value Δp. Correction value Δp for the transmitted signal down When calculated, the correction value Δp down Use the transmission parameter p TX You may decide that. p TX =p UE -Δp ···(3)

[0092] As another example, the parameter determination unit 140 determines the received parameter p RX target parameter p UE Alternatively, it may be determined by the following equation (4) based on the correction value Δp. Correction value Δp for received signal up When calculated, the correction value Δp up Use the received parameter p RX You may decide that. p RX =p UE +Δp ···(4)

[0093] For example, if the parameter is frequency, then p UEΔp is the target reception frequency at the wireless terminal 200, and Δp corresponds to the frequency fluctuation caused by the Doppler shift of the downlink or uplink estimated by this embodiment. If Δp is equivalent to the actual frequency fluctuation of the downlink, the reception frequency at the wireless terminal 200 is set to the target value p UE It is possible to do so.

[0094] As another example, if the parameter is the transmission / reception timing, then p UE Δp is the target reception timing at the wireless terminal 200, and Δp corresponds to the propagation delay in the downlink or uplink estimated by this embodiment. If Δp is equivalent to the actual propagation delay of the downlink, the reception timing at the wireless terminal 200 is set to the target value p UE It is possible to do so.

[0095] Figure 15 shows examples of operation of a base station device 100 according to several embodiments. Figure 15 shows an example in which the base station device 100 corrects the downlink signal and uplink signal using a first means.

[0096] First, the base station device 100 determines the initial values ​​of the transmission parameters in order to transmit the downlink signal (S101). For example, the parameter determination unit 140 determines the target parameter p UE Send parameter p TX Determine the initial value.

[0097] Next, the base station device 100 transmits a downlink signal with the transmission parameters set (S102). For example, the signal correction unit 122b modulates the downlink signal modulated by the modulation unit 124 with the transmission parameter p TX The target parameter p UE The setting is configured. The transmitting / receiving unit 110 sets the target parameter p UE It transmits the downlink signal that has been set.

[0098] Next, the base station device 100 receives an uplink signal from the wireless terminal 200 (S103). The base station device 100 receives the target parameter p UEWhen a downlink signal with the target parameter p is transmitted, the wireless terminal 200 will set the target parameter p UE The downlink signal is received, with the downlink frequency fluctuation or propagation delay added to it. The wireless terminal 200 performs AFC or transmit / receive timing control and transmits an uplink signal synchronized with the received downlink signal. That is, the target parameter p UE It transmits an uplink signal that has been modified by the frequency fluctuations or propagation delay of the downlink.

[0099] The transmitting / receiving unit 110 receives the uplink signal transmitted from the wireless terminal 200 after synchronization. The transmitting / receiving unit also receives the uplink signal transmitted from the wireless terminal 200, which is further affected by uplink frequency fluctuations or propagation delays.

[0100] Furthermore, the uplink signal transmitted from the wireless terminal 200 before synchronization may be received. Even if the measurement of the received parameters (S104) and the calculation of the correction value (S105) are performed using the uplink signal transmitted before synchronization, the correction can be performed to a value close to that obtained when using the uplink signal transmitted after synchronization. Also, even when using the uplink signal transmitted before synchronization, the correction value will converge to the post-synchronization value by performing the measurement of the received parameters (S104) and the calculation of the correction value (S105) using the uplink signal repeatedly transmitted from the wireless terminal 200.

[0101] Next, the base station device 100 measures the reception parameters of the received uplink signal (S104). The reception parameter measurement unit 121 measures the reception parameters p of the uplink signal from the wireless terminal 200 received by the transmitting / receiving unit 110. RX meas Measure.

[0102] Next, the base station device 100 calculates a correction value by the first means (S105). The correction value calculation unit 130 calculates the transmission parameter p of the downlink signal determined in S101. TX And the measurement reception parameter p of the uplink signal measured in S104. RX measBased on the difference, the correction value Δp is calculated. Specifically, the correction value is calculated using either equation (1) or equation (2) above.

[0103] Next, the base station device 100 determines the transmission and reception parameters based on the calculated correction values ​​(S106). The parameter determination unit 140 determines the target parameter p UE Based on the calculated correction value Δp, the transmission parameter p TX This is determined. Specifically, the transmission parameters are determined by the above formula (3).

[0104] Furthermore, the parameter determination unit 140 determines the target parameter p UE Based on the calculated correction value Δp, the received parameter p RX This is determined. Specifically, the receiving parameters are determined by the above equation (4).

[0105] Next, the base station device 100 corrects the downlink signal based on the determined transmission parameters (S107) and transmits the corrected downlink signal (S108). The signal correction unit 122b modulates the downlink signal modulated by the modulation unit 124 with the determined transmission parameters p TX The signal is corrected by the following. The transmitting / receiving unit 110 transmits the corrected downlink signal.

[0106] Next, the base station device 100 receives an uplink signal from the wireless terminal 200 (S109). The base station device 100 receives the target parameter p UE The transmission parameter p corrected by the correction value. TX When the downlink signal is transmitted, the wireless terminal 200 calculates the target parameter p in addition to the frequency fluctuation or propagation delay of the downlink. UE The downlink signal is received. The wireless terminal 200 performs AFC or transmit / receive timing control and transmits an uplink signal synchronized with the received downlink signal. That is, the target parameter p UE It transmits the uplink signal.

[0107] The transceiver 110 receives the uplink signal transmitted from the wireless terminal 200 after synchronization. The transceiver 110 receives the target parameter p transmitted from the wireless terminal 200. UE The uplink signal is received, which is subject to frequency fluctuations or propagation delays of the uplink.

[0108] Next, the base station device 100 corrects the received uplink signal based on the determined transmission parameters (S110). The signal correction unit 122a corrects the uplink signal received by the transceiver unit 110 based on the determined reception parameters p RX This is corrected by the following: As a result, the uplink signal will meet the target parameter p UE The signal is corrected. The demodulation unit 123 demodulates the uplink signal after it has been corrected by the signal correction unit 122a.

[0109] As described above, according to the second embodiment, even when parameters such as the transmission / reception frequency and transmission / reception timing in the wireless terminal fluctuate due to AFC or transmission / reception timing synchronization, the fluctuations in the parameters in the downlink and / or uplink can be appropriately measured.

[0110] Furthermore, by correcting the target parameters based on the measured and calculated downlink parameter fluctuations and transmitting the downlink signal, the transmission and reception parameters of the wireless terminal are adjusted to match the target parameters. In other words, the base station equipment can control the wireless terminal so that its transmission and reception parameters match any desired target parameters.

[0111] Furthermore, by correcting the target parameters based on correction values ​​corresponding to the parameter fluctuations of the uplink measured and calculated, and receiving the uplink signal, it becomes possible to receive the signal without being affected by parameter fluctuations in the uplink.

[0112] Furthermore, in this embodiment, when multiple base station devices are operating simultaneously, the target parameter p UEBy setting this parameter commonly, the reception parameters at the wireless terminal for downlink signals transmitted from multiple base station devices will all be set to the target parameter p UE This makes it possible to compensate for the effects of different Doppler shifts and propagation delays between multiple base stations when a wireless terminal switches connections between different base station devices or when simultaneous transmission and reception is performed, allowing the wireless terminal to receive signals at the same frequency and timing. For example, if the parameter is frequency, p UE This may also be used as the center frequency of the allocated bandwidth.

[0113] (Third embodiment) Next, a third embodiment will be described. In the third embodiment, as an example of operation when multiple base station devices communicate with a wireless terminal, the configuration and operation when two base station devices communicate with a wireless terminal will be described. In this third embodiment, the first base station device operates using the first means described in the second embodiment, and the second base station device operates using the second means described in this embodiment.

[0114] Figure 16 shows an example configuration of a wireless communication system according to several embodiments. In the example in Figure 16, the wireless communication system 3 includes base station devices 100a and 100b and a wireless terminal 200. For example, base station device 100a corresponds to the first base station device 10a in Figure 6 and base station device 100 in Figure 12. Base station device 100b corresponds to the second base station device 10b in Figure 6.

[0115] The configurations of base station devices 100a and 100b are the same as those shown in Figure 13, and the configuration of the signal processing unit 120 within base station devices 100a and 100b is the same as that shown in Figure 14. That is, base station devices 100a and 100b include one or more transmitting / receiving units 110, a signal processing unit 120, a correction value calculation unit 130, and a parameter determination unit 140, similar to Figure 13, and the signal processing unit further includes a received parameter measurement unit 121 and a signal correction unit 122.

[0116] All processing units of the base station device 100a perform the same processing as in the second embodiment. That is, the base station device 100a calculates a correction value using the first means and corrects the uplink signal and / or downlink signal.

[0117] The base station device 100b calculates a correction value using the second means and corrects the downlink signal. That is, the transmitting / receiving unit 110, signal processing unit 120, parameter determination unit 140, and the receiving parameter measurement unit 121 and signal correction unit 122 included in the signal processing unit 120 of the base station device 100b perform the same processing as in the second embodiment, and the correction value calculation unit 130 calculates a correction value using the second means.

[0118] For example, the correction value calculation unit 130 of the base station device 100b corresponds to the second correction value calculation unit 13b in Figure 8. The correction value calculation unit 130 of the base station device 100b calculates the correction value Δp by the second means and notifies the parameter determination unit 140 of the calculated correction value Δp.

[0119] In the second method, the correction value calculation unit 130 calculates the measurement received parameter p notified by the received parameter measurement unit 121. RX meas And the target parameter p UE Based on the difference, the correction value Δp is calculated. Similar to the second embodiment, the target parameter p UE This may be set in common among base station devices. For example, if the parameter is frequency, p UE The center frequency of the allocated bandwidth may also be used. From base station equipment 100a, target parameter p UE You may obtain it.

[0120] In the second method, the correction value may be calculated as shown in the following calculation example.

[0121] <Example 1 of calculating the correction value for the second method> The correction value calculation unit 130 calculates the measurement reception parameter p as shown in equation (5) below. RX meas and target parameter p UEThe difference can also be calculated directly as the correction value Δp. Δp = p RX meas -p UE ...(5)

[0122] The operation of the correction value calculation unit 130 of the base station device 100b is such that when the base station device 100a performs the operation described in the second embodiment, the wireless terminal 200 sets the target parameter p UE It is assumed that synchronization has been established. Wireless terminal 200 sets target parameter p UE When transmitting an uplink signal, Δp in equation (5) corresponds to the parameter variation in the uplink. If the parameter variations in the downlink and uplink are equivalent, in calculation example 1, a value corresponding to the parameter variation in the downlink can be calculated as the correction value.

[0123] <Example 2 of calculating the correction value for the second method> The correction value calculation unit 130 calculates the measurement reception parameter p as shown in equation (6) below. RX meas and target parameter p UE Alternatively, the difference may be multiplied by an arbitrary coefficient k (the difference multiplied by a constant) to calculate the correction value Δp. Δp=(p RX meas -p UE )·k ···(6)

[0124] Calculation Example 2 is a generalized example of Calculation Example 1, in which, when the parameter fluctuations in the downlink and uplink differ, the coefficient k is determined according to the difference in the parameter fluctuations, thereby allowing the calculation of a correction value corresponding to the parameter fluctuation in the downlink from the parameter fluctuation in the uplink. In the second method, the uplink signal is not corrected, so the coefficient k is the coefficient for the downlink, and Δp is the correction value for the transmitted signal.

[0125] Figure 17 shows an example of operation of a base station device 100b according to several embodiments. Figure 17 shows an example in which the base station device 100b corrects the downlink signal using a second means. Here, as an example, an example in which the base station device 100b corrects the downlink signal is described, but the base station device 100b may also correct the uplink signal it receives based on the correction value calculated by the second means. That is, the correction value calculation unit 130 may calculate the correction value using the second means, and the parameter determination unit 140 may determine the received parameters based on the calculated correction value (similar to equation (4) in the second embodiment).

[0126] First, the base station device 100b receives the uplink signal from the wireless terminal 200 (S201). As shown in S101-S108 of Figure 15, the base station device 100a sets the target parameter p UE The transmission parameter p corrected by the correction value. TX The downlink signal is transmitted, and the wireless terminal 200 sets the target parameter p UE Assume it is synchronized. The wireless terminal 200 synchronizes the target parameter p with the received downlink signal. UE It transmits the uplink signal.

[0127] The transceiver 110 receives the uplink signal transmitted from the wireless terminal 200 after synchronization. The transceiver 110 receives the target parameter p transmitted from the wireless terminal 200. UE The system receives an uplink signal to which frequency fluctuations or propagation delays (frequency fluctuations or propagation delays between the base station equipment 100b and the wireless terminal 200) have been added.

[0128] Next, the base station device 100b measures the received parameters of the uplink signal (S202). The received parameter measurement unit 121 measures the received parameters p of the uplink signal from the wireless terminal 200 received by the transmitting / receiving unit 110. RX meas Measure.

[0129] Next, the base station device 100b calculates a correction value by a second means (S203). The correction value calculation unit 130 calculates the target parameter p UE And the measured uplink signal measurement receiving parameter p RX meas Based on the difference, the correction value Δp is calculated. Specifically, the correction value is calculated using equation (5) or equation (6) above.

[0130] Next, the base station device 100b determines the transmission parameters based on the calculated correction value (S204). The parameter determination unit 140 determines the target parameter p UE Based on the calculated correction value Δp, the transmission parameter p TX This is determined. Specifically, the transmission parameters are determined by equation (3) above, similar to the second embodiment.

[0131] Next, the base station device 100b corrects the downlink signal based on the determined transmission parameters (S205) and transmits the corrected downlink signal (S206). The signal correction unit 122b modulates the downlink signal modulated by the modulation unit 124 with the determined transmission parameters p TX The signal is corrected by the following. The transmitting / receiving unit 110 transmits the corrected downlink signal.

[0132] Target parameter p from base station device 100b UE The transmission parameter p corrected by the correction value. TX When the downlink signal is transmitted, the wireless terminal 200 receives the target parameter p in addition to the frequency fluctuation or propagation delay of the downlink between the base station equipment 100b and the wireless terminal 200. UE The downlink signal is received. That is, the wireless terminal 200 receives the target parameter p from the base station equipment 100a by the first means. UE In addition to receiving the downlink signal, the base station equipment 100b provides the target parameter p by a second means. UE It receives the downlink signal.

[0133] As described above, according to the third embodiment, when a wireless terminal performs JT or DPS with multiple base station devices, assuming that the wireless terminal has established synchronization with a specific base station device using the first means described in the second embodiment, one or more other base station devices can communicate with the wireless terminal using the second means, thereby enabling communication with the wireless terminal's transmission and reception parameters as target parameters.

[0134] In a base station device using the second method, when determining the transmission parameters, the transmission parameters p previously determined by the transmission parameter determination unit are used. TX Since it does not require a downlink reference signal, it is unnecessary to transmit a downlink reference signal to the wireless terminal. In other words, when a wireless terminal performs JT or DPS with multiple base station devices, if at least one base station device communicates with the wireless terminal using the first means and establishes synchronization, then one or more other base station devices can communicate using the second means, enabling them to communicate properly with the wireless terminal without transmitting a downlink reference signal for synchronization. Not transmitting a downlink reference signal has advantages such as improved efficiency in utilizing wireless resources and reduced processing load on the wireless terminal.

[0135] (Fourth embodiment) Next, a fourth embodiment will be described. In the fourth embodiment, as an example of operation when multiple base station devices communicate with a wireless terminal, the operation of a base station device operating using the first or second means instructing other base station devices on the means it will use or the means that other base station devices will use will be described.

[0136] In this fourth embodiment, the first base station device operates using the first means described in the second embodiment, and the second base station device operates using the second means described in the third embodiment.

[0137] An example of the configuration of the wireless communication system in the fourth embodiment is the same as the configuration shown in Figure 16. That is, the wireless communication system 3 comprises base station devices 100a and 100b and a wireless terminal 200. Base station devices 100a and 100b can communicate with each other via an inter-base station interface.

[0138] Figure 18 shows an example configuration of a base station device according to several embodiments. In the example in Figure 18, base station devices 100a and 100b each include a transmitting / receiving unit 110, a signal processing unit 120, a correction value calculation unit 130, and a parameter determination unit 140, and further include a means determination / notification unit 150. The transmitting / receiving unit 110, the signal processing unit 120, the correction value calculation unit 130, and the parameter determination unit 140 perform the same operations as in the examples described in the second and third embodiments.

[0139] The means determination and notification unit 150 determines the means to be used by its own and / or other base station equipment's correction value calculation unit 130, that is, whether to use the first means or the second means. The means determination and notification unit 150 is a selection unit that selects the first means or the second means. The means determination and notification unit 150 also has the function of notifying its own correction value calculation unit 130 and / or other base station equipment's means determination and notification unit 150 of information indicating the determined means. The means determination and notification unit 150 is a notification unit that notifies information indicating the selected first means or second means. The means determination and notification unit 150 may notify the means to be used by its own base station equipment's correction value calculation unit 130, or it may notify the means to be used by other base station equipment's correction value calculation unit 130. The information indicating the means may be transmitted between base station equipment, for example, via the X2 / Xn interface. Alternatively, the information indicating the means may be transmitted via a higher-level control device of the base station equipment. For example, a control device higher up than the base station equipment may include a means determination and notification unit 150, and the means determination and notification unit 150 of the control device may determine the means for each base station equipment and notify each base station equipment of information indicating the determined means.

[0140] The correction value calculation unit 130 calculates the correction value as described in the second and third embodiments using the means indicated by the means information notified by the means determination and notification unit 150, and the parameter determination unit 140 determines the transmission parameter p based on the calculated correction value. TX or / and received parameter p RX To decide.

[0141] For example, the means determination and notification unit 150 may determine the means as in the following example.

[0142] <Example 1 of determining the means> The means determination and notification unit 150 may determine the means based on the connection status with the wireless terminal 200. The connection status may be, for example, the connection relationship with the cell or beam that the wireless terminal 200 has primarily selected / connected to, and can be determined by the cell ID or beam ID.

[0143] As an example, when the means determination and notification unit 150 determines the means to be used by the correction value calculation unit 130 of itself and other base station devices, it may determine that the first means is used for the correction value calculation unit 130 of the base station device indicated by the cell ID that the wireless terminal 200 has mainly selected / connected to (e.g., the cell ID of the primary cell), and the second means is used for the correction value calculation unit 130 of the base station device indicated by the cell ID that the wireless terminal 200 has not mainly selected / connected to (e.g., the cell ID of the secondary cell). The cell ID that the wireless terminal 200 has mainly selected / connected to and the cell ID that the wireless terminal 200 has not mainly selected / connected to may be obtained from the wireless terminal 200, or from other base station devices or other devices.

[0144] Furthermore, when the means determination and notification unit 150 determines the means to be used by the correction value calculation unit 130 of its own base station equipment, if the cell ID that the wireless terminal 200 primarily selects / connects to is the cell ID of its own base station equipment, it may determine the means to be used by its own correction value calculation unit 130 as the first means, and if the cell ID that the wireless terminal 200 does not primarily select / connect to is the cell ID of its own base station equipment, it may determine the means to be used by its own correction value calculation unit 130 as the second means.

[0145] <Example of determining the means 2> The means determination and notification unit 150 may determine the means based on channel status information between it and the wireless terminal 200. The channel status information may be, for example, information representing the channel gain between the wireless terminal 200 and the base station equipment.

[0146] As an example, when the means determination and notification unit 150 determines the means to be used by the correction value calculation unit 130 of itself and other base station devices, it may determine that the first means is used for the correction value calculation unit 130 of the base station device with the largest channel gain for the wireless terminal 200, and the second means is used for the correction value calculation unit 130 of the other base station devices. The channel gain of each base station device may be obtained from the wireless terminal 200, or from other base station devices or other devices.

[0147] Furthermore, the means determination and notification unit 150 may determine the means to be used by its correction value calculation unit 130 to be the first means if its own base station device is the base station device with the highest channel gain, and may determine the means to be used by its correction value calculation unit 130 to be the second means if its own base station device is not the base station device with the highest channel gain.

[0148] <Example 3 of determining the means> When the means determination and notification unit 150 receives notification of information indicating means from the means determination and notification unit 150 of another base station device that has determined means according to the above determination example 1 or determination example 2, the means to be used by the correction value calculation unit 130 of its own base station device may be determined based on the notified information indicating means.

[0149] For example, if the means determination and notification unit 150 receives information from another base station device (e.g., 100a) indicating that the means determination and notification unit 150 of the other base station device will use the first means, it may determine that the means to be used by the correction value calculation unit 130 of its own base station device (e.g., 100b) will be the second means. If the means determination and notification unit 150 receives information from another base station device indicating that the means determination and notification unit 150 of the other base station device will use the second means, it may determine that the means to be used by the correction value calculation unit 130 of its own base station device will be the first means.

[0150] Furthermore, if the means determination and notification unit 150 receives information from another base station device (e.g., 100a) indicating that its own base station device (e.g., 100b) means determination and notification unit 150 will use the first means, it may determine that the means to be used by its own base station device's correction value calculation unit 130 will be the first means. If the means determination and notification unit 150 receives information from another base station device indicating that its own base station device's means determination and notification unit 150 will use the second means, it may determine that the means to be used by its own base station device's correction value calculation unit 130 will be the second means.

[0151] As described above, according to the fourth embodiment, when multiple base station devices communicate with a wireless terminal using JT or DPS, it is possible for the base station devices to cooperate and appropriately use the first and second means. For example, if the base station device with the highest channel gain between itself and the wireless terminal uses the first means, the other base station devices can use the second means, thereby reducing the transmission of downlink reference signals.

[0152] (Fifth embodiment) Next, a fifth embodiment will be described. In the fifth embodiment, when multiple wireless terminals communicate simultaneously with one or more base station devices, the operation of correcting the signal parameters for each wireless terminal will be described.

[0153] Here, simultaneous communication primarily refers to cases where multiple wireless terminals communicate using the same time resources at the same time using methods such as Frequency Division Multiple Access (FDMA) or Spatial Division Multiple Access (SDMA).

[0154] Figure 19 shows an example configuration of a wireless communication system according to several embodiments. In Figure 19, as an example, the wireless communication system 4 comprises one base station device 100 and two wireless terminals 200a and 200b. For example, one base station device 100 and two wireless terminals 200a and 200b communicate simultaneously. The base station device 100 in Figure 19 corresponds to either the base station device 100 in Figure 12 or the base station devices 100a and 100b in Figure 16.

[0155] The configuration of the base station device 100 is the same as that shown in Figure 13 or Figure 18, except for the detailed configuration of the signal processing unit 120.

[0156] Figures 20 and 21 show examples of the configuration of a signal processing unit according to several embodiments. Figure 20 shows an example of the configuration for transmitting downlink signals included in the signal processing unit 120, and Figure 21 shows an example of the configuration for receiving uplink signals included in the signal processing unit. However, as an example, a configuration is shown in which one base station device 100 communicates with two wireless terminals 200 simultaneously. In this embodiment, the signal processing unit 120 performs parameter correction separately for each signal from the multiple wireless terminals 200 that communicate simultaneously.

[0157] In the downlink configuration example shown in Figure 20, the signal processing unit 120 includes a modulation unit 124, a signal correction unit 122b, and an IFFT 125a (the IFFT portion of FFT / IFFT 125), similar to those in Figure 14, and includes two signal correction units 122b-1 and 122b-2 for the downlink signals of the two wireless terminals 200.

[0158] The parameter determination unit 140 notifies the signal correction unit 122b-1 of the transmission parameters based on the correction value of wireless terminal 200a, and notifies the signal correction unit 122b-2 of the transmission parameters based on the correction value of wireless terminal 200b. The modulation unit 124 outputs a signal for each wireless terminal 200, and the signal correction units 122b-1 and 122b-2 correct the signal for each wireless terminal 200 based on different parameters. The corrected signals for each wireless terminal 200 are combined or concatenated according to the multiplexing scheme, then converted into a time-domain signal by IFFT 125a and transmitted to the transmitting / receiving unit 110.

[0159] In the example uplink configuration shown in Figure 21, the signal processing unit 120 includes a demodulation unit 123, a signal correction unit 122a, and an FFT unit 125b (the FFT unit of the FFT / IFFT unit 125), similar to those in Figure 14. It also includes two signal correction units 122a-1 and 122a-2 for the uplink signals of the two wireless terminals 200, and two reception parameter measurement units 121-1 and 121-2 for the uplink signals of the two wireless terminals 200.

[0160] The parameter determination unit 140 notifies the signal correction unit 122a-1 of the received parameters based on the correction value of the wireless terminal 200a, and notifies the signal correction unit 122a-2 of the received parameters based on the correction value of the wireless terminal 200a.

[0161] The uplink signal transmitted from the transceiver 110 is converted to the frequency domain by FFT 125b, and then the signals for each wireless terminal 200 are separated by extracting only the signals of the subcarriers assigned to each wireless terminal 200. However, the above separation is only possible when using FDMA, in which the signals for each wireless terminal 200 are multiplexed onto different subcarriers. Therefore, the operation during uplink reception is only effective with FDMA and not with SDMA.

[0162] The reception parameter measurement units 121-1 and 121-2 measure reception parameters based on signals separated for each wireless terminal 200 and notify the correction value calculation unit 130 of the reception parameters measured for each wireless terminal 200 (uplink signal). The signal correction units 122a-1 and 122a-2 correct each separated signal from the wireless terminal 200 based on the reception parameters notified by the parameter determination unit 140.

[0163] In the examples in Figures 20 and 21, for convenience, different signal correction units 122 and reception parameter measurement units 121 are shown for each signal from the wireless terminal 200. However, it is not necessary to use different processing units for each signal from the wireless terminal 200; the same processing unit may be used for signals from multiple wireless terminals 200.

[0164] In this embodiment, the base station device 100's correction value calculation unit 130, parameter determination unit 140, and means determination / notification unit 150 perform basic operations similar to those in the second, third, and fourth embodiments, but process independently for each wireless terminal 200. In Figure 21, the received parameter measurement units 121-1 and 121-2 measure the received parameters for each wireless terminal 200 and notify the correction value calculation unit 130, so that the subsequent correction value calculation unit 130, parameter determination unit 140, and means determination / notification unit 150 can process each wireless terminal 200.

[0165] (Modified version of the fifth embodiment) As described in the second embodiment, signal parameter correction can be simplified by appropriately converting the signal to the time domain and frequency domain. For example, when the signal correction unit corrects the frequency of a signal, a complex convolution operation is required for frequency domain signals, but for time domain signals, correction can be performed with a simple multiplication operation that corrects the phase of the signal at each time step.

[0166] Figures 22 and 23 show modified configurations of the signal correction unit according to several embodiments. Figure 22 shows an example configuration of the signal correction unit 122b for correcting downlink signals, and Figure 23 shows an example configuration of the signal correction unit 122a for correcting uplink signals. In these modified configurations, the signal correction units 122a and 122b are further equipped with FFT / IFFT modules that have a frequency-to-time conversion function for signals.

[0167] The example in Figure 22 assumes that the signal correction unit 122b corrects the signal frequency during downlink transmission. Without an FFT / IFFT module, complex convolution operations are required to correct the frequency of a frequency domain signal, but by utilizing an FFT / IFFT module, frequency correction can be performed with a simple multiplication operation.

[0168] Specifically, in the example shown in Figure 22, the signal correction unit 122b includes IFFT1221, multiplication unit 1222, and FFT1223. The frequency domain signal of the downlink input to the signal correction unit 122b is converted to a time domain signal by IFFT1221, the time domain signal and the transmission parameters from the parameter determination unit 140 are multiplied by the multiplication unit 1222, and after correction by a simple multiplication operation, it is converted back to a frequency domain signal by FFT1223. FFT1223 outputs the corrected frequency domain signal to the transmit / receive unit 110.

[0169] The example in Figure 23 assumes that the signal correction unit 122a corrects the signal frequency when receiving an uplink signal. In the example in Figure 23, the signal correction unit 122a includes IFFT1224, multiplier 1225, and FFT1226. The frequency domain signal of the uplink input to the signal correction unit 122a is converted to a time domain signal by IFFT1224, the time domain signal is multiplied by the received parameters from the parameter determination unit 140 by the multiplier 1225, and after correction by a simple multiplication operation, it is converted back to a frequency domain signal by FFT1226. FFT1226 outputs the corrected frequency domain signal to the demodulation unit 123.

[0170] This modification is not limited to the examples above, and the choice of whether or not to use the FFT / IFFT module, and whether to apply FFT or IFFT, should be appropriately selected depending on the object to be corrected and the method used.

[0171] As described above, according to the fifth embodiment, when a base station device communicates with multiple wireless terminals simultaneously, parameter correction can be performed in the base station device for both the downlink and uplink. Furthermore, according to the modified version, the parameter correction process can be simplified by performing an appropriate time-frequency conversion of the signal.

[0172] This disclosure is not limited to the embodiments described above, and may be modified as appropriate without departing from its spirit.

[0173] The above embodiments primarily focus on wireless communication systems in which a ground base station communicates with a mobile wireless terminal. However, this disclosure is not limited to ground communication systems and may also be applied to non-terrestrial networks (NTN). For example, the base station equipment in this disclosure may be mounted on a High-Altitude Platform Station (HAPS), a Low Earth Orbit satellite (LEO), a Geostationary Orbit satellite (GEO), etc.

[0174] Each configuration in the above-described embodiment is composed of hardware, software, or both, and may consist of one piece of hardware or software, or multiple pieces of hardware or software. For example, each element (function) such as a base station device or wireless terminal may be realized by a computer having a processor such as a CPU (Central Processing Unit) and memory as a storage device. For example, each element may be realized by storing a program for performing processing (methods) in the base station device, wireless terminal, etc. in memory, and executing the program stored in memory with the processor. Each element can be implemented, for example, as a network element on dedicated hardware, as a software instance running on dedicated hardware, or as a virtualization function instantiated on an application platform.

[0175] Figure 24 shows an example of the hardware configuration of a base station device according to several embodiments. In the example in Figure 24, the base station device 100 includes an RF transceiver 164, a network interface 161, a processor 162, and memory 163.

[0176] The RF transceiver 164 performs analog RF signal processing to communicate with the wireless terminal 200. The RF transceiver 164 may include multiple transceivers. The RF transceiver 164 is coupled with the antenna 164a and the processor 162. The RF transceiver 164 receives a baseband transmit signal from the processor 162, generates a transmit RF signal, and supplies the transmit RF signal to the antenna 164a. The RF transceiver 164 also generates a baseband receive signal based on the received RF signal received by the antenna 164a and supplies this to the processor 162.

[0177] The network interface 161 is used to communicate with other network devices (e.g., other base station devices). The network interface 161 may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 series. IEEE stands for Institute of Electrical and Electronics Engineers. The network interface 161 may also include an X2 / Xn interface for communication between base stations.

[0178] The processor 162 performs data plane processing and control plane processing, including digital baseband signal processing for wireless communication. For example, the digital baseband signal processing by the processor 162 may include signal processing for the Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, MAC layer, and PHY layer. The control plane processing by the processor 162 may also include processing for the RRC protocol and MAC CE.

[0179] The processor 162 may be, for example, a microprocessor, an MPU (Micro Processing Unit), or a CPU. The processor 162 may include multiple processors. For example, the processor 162 may include a modem processor (e.g., a Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., a CPU or MPU) that performs control plane processing.

[0180] Memory 163 is comprised of a combination of volatile and non-volatile memory. Memory 163 may include multiple physically independent memory devices. Volatile memory is, for example, Static Random Access Memory (SRAM) or Dynamic RAM (DRAM), or a combination thereof. Non-volatile memory is Mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, hard disk drive, or solid-state drive (SSD), or any combination thereof. Memory 163 may include storage located away from the processor 162. In this case, the processor 162 may access memory 163 via an I / O (Input / Output) interface not shown.

[0181] Memory 163 may store a software module (computer program) containing instruction sets and data for performing processing by the base station device as described in some of the embodiments above. In some implementations, the processor 162 may be configured to read the software module from memory 163 and execute it to perform the processing of the base station device as described in some of the embodiments above.

[0182] In the examples described above, the program includes a set of instructions (or software code) that, when loaded into a computer, cause the computer to perform one or more of the functions described in the embodiments. The program may be stored on a non-temporary computer-readable medium or a physical storage medium. Examples, but not limited to, include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technologies, CD-ROM, digital versatile disc (DVD), Blu-ray® disc or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices. The program may be transmitted over a temporary computer-readable medium or a communication medium. Examples, but not limited to, include temporary computer-readable medium or a communication medium that includes electrically, optically, acoustically or otherwise propagating signals.

[0183] Although the present disclosure has been described above with reference to embodiments, the present disclosure is not limited to the embodiments described above. Various modifications to the structure and details of the present disclosure can be made as can be understood by those skilled in the art within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0184] Each drawing is merely illustrative to illustrate one or more embodiments. Each drawing may be associated with one or more other embodiments rather than with only one specific embodiment. As those skilled in the art will understand, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings, for example, to create embodiments not explicitly shown or described. Not all features or steps shown in any one drawing to illustrate an exemplary embodiment are necessarily required, and some features or steps may be omitted. The order of steps shown in any of the drawings may be changed as appropriate.

[0185] Some or all of the above embodiments may also be described as follows, but are not limited to the following: (Note 1) A transmitting unit that transmits downlink signals to wireless terminals, A receiving unit that receives an uplink signal transmitted from the aforementioned wireless terminal, A first correction value calculation unit calculates a first correction value based on the difference between the transmission parameters of the transmitted downlink signal and the reception parameters of the received uplink signal. A correction unit that corrects the transmission parameters of the downlink signal to be transmitted to the wireless terminal based on the first correction value, A base station device equipped with the following features. (Note 2) The first correction value calculation unit calculates the value obtained by multiplying the difference by a coefficient as the first correction value. The base station equipment described in Appendix 1. (Note 3) The first correction value calculation unit calculates the first correction value as the value obtained by multiplying the difference by 1 / 2. Base station equipment as described in Appendix 2. (Note 4) The correction unit corrects the transmission parameters based on the target parameters at the time of receiving the downlink signal in the wireless terminal and the first correction value. A base station device as described in any one of the items 1 to 3 of the appendix. (Note 5) The correction unit uses the value obtained by subtracting the first correction value from the target parameter as the transmission parameter. Base station equipment as described in Appendix 4. (Note 6) The correction unit corrects the reception parameters of the uplink signal received from the wireless terminal based on the first correction value. A base station device as described in any one of the items 1 to 3 of the appendix. (Note 7) The correction unit corrects the received parameters based on the target parameters at the time of receiving the downlink signal in the wireless terminal and the first correction value. Base station equipment as described in Appendix 6. (Note 8) The correction unit uses the value obtained by adding the first correction value to the target parameter as the received parameter. Base station equipment as described in Appendix 7. (Note 9) The wireless terminal includes a second correction value calculation unit that calculates a second correction value based on the difference between the target parameter when receiving the downlink signal and the received parameter of the uplink signal. The correction unit corrects the transmission parameters of the downlink signal to be transmitted to the wireless terminal based on the second correction value. A base station device as described in any one of the items 1 to 3 of the appendix. (Note 10) The transmission parameters and reception parameters are information relating to the Doppler shift of the propagation path between the wireless terminal and the receiving terminal. A base station device as described in any one of the items 1 to 3 of the appendix. (Note 11) The transmission parameters and reception parameters are information regarding the propagation delay of the propagation path between the wireless terminal and the receiving terminal. A base station device as described in any one of the items 1 to 3 of the appendix. (Note 12) The system includes a selection unit that selects whether to perform the calculation of the first correction value or the calculation of the second correction value. Base station equipment as described in Appendix 9. (Note 13) The selection unit selects whether to calculate the first correction value or the second correction value based on information regarding the connection status with the wireless terminal. Base station equipment as described in Appendix 12. (Note 14) The selection unit selects whether to calculate the first correction value or the second correction value based on information regarding the channel status with the wireless terminal. The base station device described in Supplementary Note 12. (Supplementary Note 15) A notification unit that notifies other base station devices of information representing the selection result by the selection unit. The base station device described in Supplementary Note 12. (Supplementary Note 16) The selection unit selects whether to calculate the first correction value or the second correction value based on the selection result notified from the other base station device. The base station device described in Supplementary Note 15. (Supplementary Note 17) The receiving unit receives a plurality of uplink signals from a plurality of wireless terminals. The first correction value calculation unit calculates the first correction value for each of the plurality of wireless terminals. The correction unit corrects the transmission parameter for each of the plurality of wireless terminals. The base station device according to any one of Supplementary Notes 1 to 3. (Supplementary Note 18) The correction unit converts the downlink signal into the time domain or the frequency domain according to the type of the transmission parameter, and corrects the signal in the converted domain with the transmission parameter. The base station device according to any one of Supplementary Notes 1 to 3. (Supplementary Note 19) The correction unit converts the uplink signal into the time domain or the frequency domain according to the type of the reception parameter, and corrects the signal in the converted domain with the reception parameter. The base station device described in Supplementary Note 6. (Supplementary Note 20) A transmission unit that transmits a downlink signal to a wireless terminal, A receiving unit that receives an uplink signal transmitted from the wireless terminal, A second correction value calculation unit that calculates a second correction value based on a difference between a target parameter at the time of receiving the downlink signal in the wireless terminal and a reception parameter of the received uplink signal, A correction unit that corrects a transmission parameter of a downlink signal transmitted to the wireless terminal based on the second correction value, A base station device comprising the above. (Note 21) A system comprising a base station device and a wireless terminal, The base station device is, A transmitting unit that transmits a downlink signal to the wireless terminal, A receiving unit that receives an uplink signal transmitted from the aforementioned wireless terminal, A first correction value calculation unit calculates a first correction value based on the difference between the transmission parameters of the transmitted downlink signal and the reception parameters of the received uplink signal. A correction unit that corrects the transmission parameters of the downlink signal to be transmitted to the wireless terminal based on the first correction value, A system equipped with these features. (Note 22) A system comprising a base station device and a wireless terminal, The base station device is, A transmitting unit that transmits a downlink signal to the wireless terminal, A receiving unit that receives an uplink signal transmitted from the aforementioned wireless terminal, A second correction value calculation unit calculates a second correction value based on the difference between the target parameter when receiving the downlink signal in the wireless terminal and the received parameter of the uplink signal. A correction unit that corrects the transmission parameters of the downlink signal to be transmitted to the wireless terminal based on the second correction value, A system equipped with these features. (Note 23) A method for base station equipment, Transmitting downlink signals to wireless terminals, Receiving the uplink signal transmitted from the aforementioned wireless terminal, Based on the difference between the transmission parameters of the transmitted downlink signal and the received parameters of the received uplink signal, a first correction value is calculated. Based on the first correction value, the transmission parameters of the downlink signal to be transmitted to the wireless terminal are corrected, A method that includes this. (Note 24) A method for base station equipment, Transmitting downlink signals to wireless terminals, Receiving the uplink signal transmitted from the aforementioned wireless terminal, A second correction value is calculated based on the difference between the target parameter when receiving the downlink signal in the wireless terminal and the received parameter of the uplink signal. Based on the second correction value, the transmission parameters of the downlink signal to be transmitted to the wireless terminal are corrected, A method that includes this. (Note 25) A program for causing a computer to execute a method for base station equipment, The aforementioned method, Transmitting downlink signals to wireless terminals, Receiving the uplink signal transmitted from the aforementioned wireless terminal, Based on the difference between the transmission parameters of the transmitted downlink signal and the received parameters of the received uplink signal, a first correction value is calculated. Based on the first correction value, the transmission parameters of the downlink signal to be transmitted to the wireless terminal are corrected, A program that includes this. (Note 26) A program for causing a computer to execute a method for base station equipment, The aforementioned method, Transmitting downlink signals to wireless terminals, Receiving the uplink signal transmitted from the aforementioned wireless terminal, A second correction value is calculated based on the difference between the target parameter when receiving the downlink signal in the wireless terminal and the received parameter of the uplink signal. Based on the second correction value, the transmission parameters of the downlink signal to be transmitted to the wireless terminal are corrected, A program that includes this.

[0186] Some or all of the elements (e.g., configurations and functions) described in Supplementary Note 2 to Supplementary Note 19, which are subordinate to Supplementary Note 1 (base station device), may be subordinate to Supplementary Note 20 (base station device), Supplementary Note 21 (system), Supplementary Note 22 (system), Supplementary Note 23 (method), Supplementary Note 24 (method), Supplementary Note 25 (program), and Supplementary Note 26 (program) in the same subordinate relationship as Supplementary Note 2 to Supplementary Note 19. Some or all of the elements described in any supplementary note may be applicable to various hardware, software, recording means for recording software, systems, and methods.

Explanation of Signs

[0187] 1-4 Wireless communication system 10 Base station device 10a First base station device 10b Second base station device 11 Transmitter 12 Receiver 13a First correction value calculation unit 13b Second correction value calculation unit 14 Correction unit 20 Wireless terminal 31 Control device 32 Wireless device 100, 100a, 100b Base station device 110 Transceiver 120 Signal processing unit 121 Received parameter measurement unit 122, 122a, 122b Signal correction unit 123 Demodulation unit 124 Modulation unit 125 FFT / IFFT 125a IFFT 125b FFT 130 Correction value calculation unit 140 Parameter determination unit 150 Means determination and notification unit 161 Network interface 162 Processor 163 Memory 164 RF transceiver 164a Antenna 200, 200a, 200b wireless terminals 1221 IFFT 1222 Multiplication part 1223 FFT 1224 IFFT 1225 Multiplication part 1226 FFT

Claims

1. A transmitting unit that transmits downlink signals to wireless terminals, A receiving unit that receives an uplink signal transmitted from the aforementioned wireless terminal, A first correction value calculation unit calculates a first correction value based on the difference between the transmission parameters of the transmitted downlink signal and the reception parameters of the received uplink signal. A correction unit that corrects the transmission parameters of the downlink signal to be transmitted to the wireless terminal based on the first correction value, A base station device equipped with the following features.

2. The first correction value calculation unit calculates the value obtained by multiplying the difference by a coefficient as the first correction value. The base station device according to claim 1.

3. The first correction value calculation unit calculates the first correction value as the value obtained by multiplying the difference by 1 / 2. The base station device according to claim 2.

4. The correction unit corrects the transmission parameters based on the target parameters at the time of receiving the downlink signal in the wireless terminal and the first correction value. The base station device according to any one of claims 1 to 3.

5. The correction unit uses the value obtained by subtracting the first correction value from the target parameter as the transmission parameter. The base station device according to claim 4.

6. The correction unit corrects the reception parameters of the uplink signal received from the wireless terminal based on the first correction value. The base station device according to any one of claims 1 to 3.

7. The correction unit corrects the received parameters based on the target parameters at the time of receiving the downlink signal in the wireless terminal and the first correction value. The base station device according to claim 6.

8. A system comprising a base station device and a wireless terminal, The base station device is, A transmitting unit that transmits a downlink signal to the wireless terminal, A receiving unit that receives an uplink signal transmitted from the aforementioned wireless terminal, A first correction value calculation unit calculates a first correction value based on the difference between the transmission parameters of the transmitted downlink signal and the reception parameters of the received uplink signal. A correction unit that corrects the transmission parameters of the downlink signal to be transmitted to the wireless terminal based on the first correction value, A system equipped with these features.

9. A method for base station equipment, Transmitting downlink signals to wireless terminals, Receiving the uplink signal transmitted from the aforementioned wireless terminal, Based on the difference between the transmission parameters of the transmitted downlink signal and the received parameters of the received uplink signal, a first correction value is calculated. Based on the first correction value, the transmission parameters of the downlink signal to be transmitted to the wireless terminal are corrected, A method that includes this.

10. A program for causing a computer to execute a method for base station equipment, The aforementioned method, Transmitting downlink signals to wireless terminals, Receiving the uplink signal transmitted from the aforementioned wireless terminal, Based on the difference between the transmission parameters of the transmitted downlink signal and the received parameters of the received uplink signal, a first correction value is calculated. Based on the first correction value, the transmission parameters of the downlink signal to be transmitted to the wireless terminal are corrected, A program that includes this.

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