Wireless communication device
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- NIPPON TELEGRAPH & TELEPHONE CORP
- Filing Date
- 2024-12-02
- Publication Date
- 2026-06-12
Smart Images
Figure 2026096094000001_ABST
Abstract
Description
[Technical Field]
[0001] This invention relates to the technology of wireless communication devices. [Background technology]
[0002] In current TDD (Time Division Duplex)-based fifth-generation mobile communication systems, upload resources are insufficient compared to download resources, making it difficult to handle situations such as heavy upload traffic. To address this, dynamic TDD is being considered in communication systems to efficiently accommodate uplink traffic, by dynamically changing the uplink boundary for each base station in the traffic distribution. However, in dynamic TDD, uplink and downlink signals may be transmitted at the same time, leading to uplink interference (interference from downlink signals transmitted by each base station antenna against uplink signals transmitted by the terminal) at a given base station antenna reception. A conventional technique to reduce this interlink interference is the full digital canceller (see, for example, Non-Patent Document 1). In the full digital canceller, the cancellation process is performed in the digital signal domain. [Prior art documents] [Non-patent literature]
[0003] [Non-Patent Document 1] Ashutosh Sabharwal, Philip Schniter, Dongning Guo, Daniel W. Bliss, Sampath Rangarajan, and Risto Wichman, "In-Band Full-Duplex Wireless: Challenges and Opportunities", IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, VOL. 32, NO. 9, SEPTEMBER 2014 [Overview of the project] [Problems that the invention aims to solve]
[0004] However, with conventional technology, when the interference signal power increases due to the directivity of the base station antenna or the location of the terminal, quantization becomes adapted to a wide dynamic range, resulting in a decrease in quantization resolution, which degrades transmission quality and also degrades the interference cancellation accuracy in the digital signal domain. In view of the above circumstances, the present invention aims to provide a technology that can cancel residual interference in the digital signal domain with high precision. [Means for solving the problem]
[0005] One aspect of the present invention is a wireless communication device that transmits a plurality of transmission signals and receives at least one reception signal, comprising: a determination unit that uses propagation information between antennas where interference occurs between a plurality of antennas transmitting each of the transmission signals and an antenna receiving the reception signal to calculate the power ratio of the uplink signal at the antenna where interference occurs with respect to each interfering signal; compares the power ratio with a first threshold; compares the power ratio with a second threshold if the power ratio is less than the first threshold; reduces interference between the uplink and downlinks in the analog signal domain if the power ratio is greater than or equal to the second threshold; and reduces interference between the uplink and downlinks in the digital signal domain if the power ratio is greater than or equal to the second threshold. [Effects of the Invention]
[0006] According to one aspect of the present invention, amplitude adjustment can be made to match the dynamic range of the desired signal, and residual interference in the digital signal domain can be canceled with high precision, thereby improving transmission quality. [Brief explanation of the drawing]
[0007] [Figure 1] This figure shows an example of the configuration of a conventional wireless communication system. [Figure 2] This figure shows an example of base station antenna transmission and reception over time. [Figure 3] It is a diagram showing a configuration example of a wireless communication device according to the first embodiment. [Figure 4] It is a diagram for explaining the outline of the cancellation process. [Figure 5] It is a flowchart of the cancellation process of the wireless communication device according to the first embodiment. [Figure 6] It is a diagram showing a configuration example of a wireless communication device according to the second embodiment. [Figure 7] It is a flowchart of the cancellation process of the wireless communication device according to the second embodiment. [Figure 8] It is a diagram showing an outline of a hardware configuration example of an information processing apparatus applied to the embodiment.
Mode for Carrying Out the Invention
[0008] Embodiments of the present invention will be described in detail with reference to the drawings.
[0009] (Interference between uplink and downlink) First, the interference between the uplink and downlink in the prior art will be described while referring to FIGS. 1 and 2. FIG. 1 is a diagram showing a configuration example of a wireless communication system in the prior art. As shown in FIG. 1, the wireless communication system includes base stations 900-1, 900-2, 900-N, and terminals 920-1, 920-2, 920-N. An antenna 911-1 is connected to the base station 900-1, an antenna 911-2 is connected to the base station 900-2, and an antenna 911-N is connected to the base station 900-N.
[0010] The terminals 920-1, 920-2, 920-N are, for example, smartphones, tablet terminals, personal computers having a communication function, game devices, and dedicated terminals. Arrow g1 is a transmission signal (downlink signal) from the antenna 911-1 of the base station 900-1 to the terminal 920-1. Arrow g3 is a transmission signal (downlink signal) from the antenna 911-2 of the base station 900-2 to the terminal 920-2. Arrow g5 indicates the transmission signal (uplink signal) from terminal 920-N to antenna 911-N of base station 900-N. Arrow g2 represents the downlink interference signal from antenna 911-1 of base station 900-1 to antenna 911-N of base station 900-N. Arrow g4 represents the downlink interference signal from antenna 911-2 of base station 900-2 to antenna 911-N of base station 900-N.
[0011] Figure 2 shows an example of base station antenna transmission and reception over time. The horizontal axis represents time. Code g10 is the transmitted signal from antenna 911-1 of base station 900-1. Hatching g11 indicates the transmission period of the uplink signal, and hatching g12 indicates the transmission period of the downlink signal. Code g15 is the transmitted signal from antenna 911-2 of base station 900-2. Code g17 is the transmitted signal from terminal 920-N. Time t1 is an example of a timing when interference occurs while both uplink and downlink signals are present.
[0012] In dynamic TDD, uplink and downlink signals may be transmitted at the same time, which can lead to interlink interference (interference from downlink signals transmitted by each base station antenna against the uplink signal transmitted by the terminal) at a given base station antenna reception, as shown in Figure 2.
[0013] Here, depending on the position of the terminal 920 housed by antenna 911-N, the interference power of the downlink signal from antenna 911-1 (or antenna 911-2) of another base station 900-1 (or base station 900-2) may be greater than the received power of the desired uplink signal from the terminal 920. In such a state containing a large interference signal, if the signal passes through the automatic gain adjustment function, the power adjustment will be based on the power of the desired signal and the interference signal. As a result, even if interference rejection is performed in the digital domain, the dynamic range of the desired signal will be lost, and quality degradation will occur. This condition also depends heavily on the directivity of the antenna, for example. Because the transmission power of terminal 920 is smaller than that of antenna 911 of base station 900, interference signals tend to be stronger. In addition, depending on the relative positions of antenna 911 of base station 900 and terminal 920, and the directivity of antenna 911 of base station 900, very large interference may occur.
[0014] In this embodiment, interference rejection processing is performed in both the analog signal domain and the digital signal domain to cancel such interference between the upper and lower links. In this embodiment, interference rejection is performed in the analog domain to the extent that the desired dynamic range of the signal can be obtained.
[0015] <First Embodiment> Figure 3 shows an example of the configuration of the wireless communication device of this embodiment. As shown in Figure 3, the wireless communication device 1 includes, for example, a first modulator 101, a first DA converter 102, a second modulator 103, a second DA converter 104, a storage unit 105, a determination unit 106, a first adjustment unit 107, a second adjustment unit 108, a first calculation unit 109, an AGC 110, an AD converter 111, a second calculation unit 112, and a demodulation unit 113. Furthermore, the wireless communication device 1 is connected to base station antennas 11-1 to 11-N (where N is an integer of 3 or greater).
[0016] The example in Figure 3 shows a configuration where downlink signals are transmitted from base station antennas 11-1 and 11-2, and uplink signals and downlink interference signals are received by base station antenna 11-N. Each of base station antennas 11-1 through 11-N is equipped with a transmitting unit and a receiving unit. The configuration is such that there is no problem regardless of which of the base station antennas 11-1 through 11-N is used for transmitting downlink signals and receiving uplink signals.
[0017] The wireless communication device 1 is, for example, an integrated base station that combines the functions of multiple base stations.
[0018] The first modulator 101 modulates the first upstream signal using a predetermined modulation scheme and outputs the modulated signal to the first DA converter 102.
[0019] The first DA converter 102 converts the modulated first uplink signal output by the first modulator 101 from a digital signal to an analog signal, and transmits the converted first uplink signal using the base station antenna 11-1.
[0020] The second modulator 103 modulates the second upstream signal using a predetermined modulation scheme and outputs the modulated signal to the second DA converter 104.
[0021] The second DA converter 104 converts the modulated second uplink signal output by the second modulator 103 from a digital signal to an analog signal, and transmits the converted second uplink signal using the base station antenna 11-2.
[0022] The memory unit 105 stores propagation information (attenuation, delay time, phase difference) between each antenna, which has been measured in advance, as a table. For example, the administrator of a communication system may measure interference between base station antennas in advance. For example, when installing antennas, propagation information (attenuation, delay time, phase difference) between each antenna is measured and stored in the memory unit 105 as a table. Attenuation, delay time, and phase difference can be measured using information on each transmitted signal shared between base stations. The memory unit 105 also stores a first threshold and a second threshold used for cancellation determination.
[0023] The determination unit 106 receives information such as the desired signal power of the signal received by the base station antenna 11-N. Based on the power of the received signal and the interference signal information obtained from the antenna propagation information held by the memory unit, the determination unit 106 determines whether to perform interference rejection in the analog domain by the first adjustment unit 107, to perform interference rejection in the digital domain by the second adjustment unit 108, or to perform interference rejection itself. The determination method will be described later.
[0024] The first adjustment unit 107 adjusts the amplitude, delay, and phase if the determination result of the determination unit 106 indicates that adjustments should be made by the first adjustment unit 107.
[0025] The second adjustment unit 108 adjusts the amplitude, delay, and phase if the determination result of the determination unit 106 indicates that adjustments should be made by the second adjustment unit 108.
[0026] Based on the determination by the determination unit 106, the first calculation unit 109 cancels interference signals in the analog signal domain by inverse-phase synthesis of the signal whose amplitude, delay, and phase have been adjusted by the first adjustment unit 107 with the received signal received by the base station antenna 11-N.
[0027] The AGC110 is an automatic gain control unit. The AGC110 performs gain adjustment (e.g., amplitude adjustment) in the analog signal domain for the received signal input from the first arithmetic unit 109.
[0028] The AD converter 111 converts the received signal, after the AGC 110 has performed gain adjustment (e.g., amplitude adjustment), from an analog signal to a digital signal.
[0029] Based on the determination of the determination unit 106, the second calculation unit 112 cancels interference signals in the analog signal domain by inverse-phase synthesis of the signal whose amplitude, delay, and phase have been adjusted by the second adjustment unit 108 with the received signal received by the base station antenna 11-N.
[0030] The demodulation unit 113 demodulates the received signal, from which interference signals have been canceled, using a predetermined demodulation method.
[0031] (Overview of the cancellation process) Next, the general outline of the cancellation process in the wireless communication device 1 will be explained using the signal spectrum of each part. Figure 4 is a diagram illustrating the general outline of the cancellation process. Code g20 is an image of the transmission spectrum at base station antenna 11-1. Code g30 is an image of the transmission spectrum at base station antenna 11-2. Code g40 is an image of the received spectrum at base station antenna 11-N. Code 41 is the transmitted spectrum at base station antenna 11-1, code 42 is the transmitted spectrum at base station antenna 11-2, and code 43 is the spectrum of the desired signal. Code g50 is an image of the spectrum after interference cancellation in the analog signal domain. Code g51 is the transmission spectrum at base station antenna 11-2, and code g52 is the spectrum of the desired signal. Code g60 is an image of quantization after automatic gain adjustment and conversion to a digital signal. Code 61 is an image of the quantization of the transmission spectrum at the base station antenna 11-2 after gain adjustment, and code 62 is an image of the quantization of the spectrum of the desired signal after gain adjustment (e.g., amplitude adjustment). Code g70 is an illustrative diagram of quantization after interference cancellation in the digital signal domain. The dashed horizontal line represents the dynamic range. In the cases g20 to g50, the horizontal axis represents frequency and the vertical axis represents level. In the cases g60 to g70, the horizontal axis represents frequency and the vertical axis represents level. The dashed line represents the quantization interval.
[0032] In the example shown in Figure 4, the power of the signal transmitted from base station antenna 11-1 (g41) is greater than the power of the signal transmitted from base station antenna 11-2 (g42), as indicated by the code g40. In processing in the digital signal domain, a signal with high power relative to the desired signal (g43) reduces the quantization resolution of the desired signal. Therefore, in this embodiment, as indicated by the code g60, the transmission spectrum from base station antenna 11-2, which is interference that greatly affects the quantization resolution of the desired signal, is canceled in the analog signal domain before quantization.
[0033] After canceling interference in the analog signal domain, automatic gain adjustment is performed in the analog signal domain. After automatic gain adjustment, the analog signal is converted to a digital signal and quantized, as shown by code g60. Furthermore, in this embodiment, the transmitted spectrum component at the base station antenna 11-1, which is interference that has little effect on the quantization resolution of the desired signal, is canceled in the digital signal domain, as shown by code g70.
[0034] Thus, the interference cancellation in this embodiment is an interference canceller that separates the analog signal domain and the digital signal domain. The analog signal domain is the area enclosed by the dashed rectangle g81 in Figure 2, and the digital signal domain is the area enclosed by the dashed rectangle g82 in Figure 2.
[0035] (Example of processing procedure) Next, an example of the cancellation procedure for the wireless communication device 1 will be described. Figure 5 is a flowchart of the cancellation procedure for the wireless communication device in this embodiment.
[0036] (Step S1) The determination unit 106 determines whether or not the TDD frame has been changed. For example, the determination unit 106 determines whether or not the TDD frame (beamset of base station and UE (User Equipment; user terminal)) has been changed since the previous interference cancellation process. If the determination unit 106 determines that the TDD frame has been changed (Step S1; YES), it proceeds to the process in Step S2. If the determination unit 106 determines that the TDD frame has not been changed (Step S1; NO), it proceeds to the process in Step S4.
[0037] (Step S2) The determination unit 106 identifies the base station antenna 11 causing interference between the uplink and downlink based on the status of each TDD frame. For example, the determination unit 106 identifies it by estimating from the positional relationship and beamset of the base stations that are transmitting and receiving signals.
[0038] (Step S3) The determination unit 106 obtains the inter-antenna propagation information for the base station antenna 11 identified in step S3 from the storage unit 105.
[0039] (Step S4) The determination unit 106 determines the power ratio S / I of the uplink signal and each interference signal at the base station antenna 11 identified in step S3. n (where n is an integer from 1 to N-1) is obtained. For example, the determination unit 106 obtains the power ratio S / I from the acquired inter-antenna propagation information and beam information. n Calculate.
[0040] (Step S5) The determination unit 106 sorts the power ratio S / I n in ascending order. Or, the determination unit 106 sorts S and I n in descending order of the difference therebetween. Assume that interference signals from a plurality (n, 1, …, N) of base station antennas are included in the uplink signal.
[0041] (Step S6) The determination unit 106 determines whether there is an interference signal that has not been removed. When there is an interference signal that has not been removed (Step S6; YES), the determination unit 106 proceeds to the process of Step S7. When there is no interference signal that has not been removed (Step S6; NO), the determination unit 106 ends the cancellation process.
[0042] (Step S7) The determination unit 106 compares the power ratio S / I n in ascending order (or in descending order of the difference between S and I n ) with a first threshold value T1, and determines whether the power ratio S / I n is less than the first threshold value T1 (S / I n < T1). The significance of this determination is to determine from the threshold value T1 whether interference cancellation in the digital domain is also unnecessary. The determination can be made, for example, based on whether there is an interference signal of such a magnitude that a block error would occur even if interference cancellation is performed in the analog domain and the digital domain. For example, it is possible to estimate from the SINR (Signal to Interference plus Noise Ratio) based on the sum of I n . When the power ratio S / I n is less than the first threshold value T1 (Step S7; YES), the determination unit 106 proceeds to the process of Step S8. When the power ratio S / I n is greater than or equal to the first threshold value T1 (Step S7; NO), the determination unit 106 ends the cancellation process.
[0043] (Step S8) The determination unit 106 compares the power ratio S / I n in ascending order (or in descending order of the difference between S and I n ) with a second threshold value T2, and determines whether the power ratio S / I n is less than the second threshold value T2 (S / I nDetermine whether it is <T2). The meaning of this determination is to determine from the threshold value T2 whether interference cancellation in the analog domain is necessary. In this embodiment, on the premise of implementing digital cancellation, for example, a threshold value is set so that block errors due to the influence of quantization do not occur, and interference cancellation is performed in the analog domain until it becomes below that threshold value. The determination unit 106 calculates the power ratio S / I n If it is less than the second threshold value T2 (step S8; YES), proceed to the process of step S9. The determination unit 106 calculates the power ratio S / I n If it is greater than or equal to the second threshold value T2 (step S8; NO), proceed to the process of step S11.
[0044] (Step S9) The determination unit 106 adjusts the amplitude, delay, and phase of each interference signal replica based on the inter-antenna propagation information acquired from the storage unit 105.
[0045] (Step S10) The first adjustment unit 107 performs inverse-phase synthesis in the analog signal domain of the interference signal replica with adjusted amplitude, delay, and phase on the corresponding antenna reception signal. After the process, the first adjustment unit 107 returns the process to step S6.
[0046] (Step S11) The determination unit 106 adjusts the amplitude, delay, and phase of each interference signal replica based on the inter-antenna propagation information acquired from the storage unit 105.
[0047] (Step S12) The second adjustment unit 108 performs inverse-phase synthesis in the digital signal domain of the interference signal replica with adjusted amplitude, delay, and phase on the corresponding antenna reception signal. After the process, the second adjustment unit 108 returns the process to step S6.
[0048] Note that the information acquired in step S4 may also be the received power of the uplink signal and the interference signal respectively at the base station antenna 11 specified in step S3. In this case, in the processes of steps S5 to S8, the received power is used for processing instead of the power ratio.
[0049] Furthermore, in the process of step S3, if there are no signal transmissions other than the one being measured, the table may be updated while periodically measuring and handling outliers.
[0050] Furthermore, in the processing of step S4, if the signal containing interference can be demodulated, the signal is first input into the digital domain without using the estimated value from the memory unit 105, and the power ratio S / I is... n You may measure and use the respective received powers instead of the power ratio in step S4.
[0051] Also, in the processing of step S5, the order of sorting is I n It would also be acceptable to list them in descending order of power consumption.
[0052] Furthermore, in the processing of step S6, signals that cannot (or are difficult) be removed may be excluded from the candidate interference signals in this determination.
[0053] Furthermore, in step S8, interference removal may be performed sequentially for each interference signal, or multiple interference signals may be combined and compared with a threshold value to remove interference from multiple signals at once.
[0054] As described above, in this embodiment, interference removal is divided between interference removal in the analog domain and interference removal in the digital domain. In this embodiment, after interference cancellation in the digital signal domain, interference cancellation is performed in the analog domain to a level where no quality degradation such as block errors occurs. In this embodiment, the determination unit 106 is configured to share the interference removal capability based on the above level.
[0055] In other words, in this embodiment, high-power interference with a wide dynamic range that reduces the quantization resolution of the desired signal after interference cancellation in a digital interference canceller is canceled in the analog signal domain before quantization. As a result, in this embodiment, the subsequent AGC110 enables amplitude adjustment to match the dynamic range of the desired signal, and by canceling residual interference in the digital signal domain with high precision, the quantization resolution of the desired signal is not reduced, making it possible to utilize it effectively.
[0056] Furthermore, when attempting to remove interference in the analog domain, for example, by inverse phase synthesis, high-quality interference removal may not be possible due to synchronization errors between signals. Therefore, in this embodiment, interference removal is performed in the digital signal domain after reducing analog processing. In addition, in this embodiment, even when reducing interference signals through scheduling adjustments, delays in resource allocation may occur if the user terminal is located in a position where interference is likely to occur. Therefore, interference removal is performed using digital signal processing.
[0057] As described above, according to this embodiment, the reduction in quantization resolution can be suppressed by reducing interference in the analog signal domain. According to this embodiment, residual interference can be processed with high precision in the digital signal domain. According to this embodiment, amplitude adjustment that matches the dynamic range of the desired signal is possible, and residual interference in the digital signal domain can be canceled with high precision, thereby improving transmission quality. According to this embodiment, the determination unit 106 can use both an analog canceller and a digital canceller to further reduce interference power until an appropriate quantization resolution is achieved.
[0058] <Second Embodiment> Furthermore, interference signal power may be reduced by scheduling adjustments, etc. In this embodiment, an example of reducing interference signal power by scheduling adjustments, etc., will be described.
[0059] Figure 6 shows an example of the configuration of the wireless communication device of this embodiment. As shown in Figure 6, the wireless communication device 1A includes, for example, a first modulator 101, a first DA converter 102, a second modulator 103, a second DA converter 104, a storage unit 105, a determination unit 106A, a first adjustment unit 107, a second adjustment unit 108, a first calculation unit 109, an AGC 110, an AD converter 111, a second calculation unit 112, and a demodulation unit 113. Furthermore, the wireless communication device 1 is connected to base station antennas 11-1 to 11-N (where N is an integer of 3 or greater).
[0060] The determination unit 106A determines whether to perform cancellation processing in the analog signal domain or the digital signal domain. In the cancellation processing in the analog signal domain, the determination unit 106A performs scheduling adjustments. Scheduling adjustments include, for example, shifting the transmission timing of the transmitting signal that becomes an interfering signal or the reception timing of the receiving signal, changing the transmitting and receiving antennas or beamsets, and avoiding the use of beamsets that have a large interfering signal power and are certain to cause errors in terms of dynamic range (quantization resolution).
[0061] Interference reduction through scheduling may cause delays in resource allocation, for example, when a user terminal is located in a position where interference is likely to be strong. In this case, the determination unit 106A determines the necessary amount of interference reduction through scheduling, taking into account interference removal in digital signal processing, thereby reducing the constraints on resource allocation and making delays in resource allocation less likely.
[0062] (Example of processing procedure) Next, an example of the cancellation procedure for the wireless communication device 1A will be described. Figure 7 is a flowchart of the cancellation procedure for the wireless communication device in this embodiment.
[0063] (Step S101) The determination unit 106A determines whether or not the TDD frame has been changed. If the TDD frame has been changed (Step S101; YES), the determination unit 106A proceeds to the process in step S102. If the TDD frame has not been changed (Step S101; NO), the determination unit 106A proceeds to the process in step S104.
[0064] (Step S102) The determination unit 106A identifies the base station antenna 11 where interference occurs between the uplink and downlink based on the status of each TDD frame.
[0065] (Step S103) The determination unit 106A obtains the inter-antenna propagation information for the base station antenna 11 identified in step S103 from the storage unit 105.
[0066] (Step S104) The determination unit 106A determines the power ratio S / I of the uplink signal and each interference signal at the base station antenna 11 identified in step S103. n Get an integer (n is an integer between 1 and N-1).
[0067] (Step S105) The determination unit 106A determines the power ratio S / I n Sort them in ascending order. Alternatively, the determination unit 106A determines S and I n Sort by the largest difference from the given value.
[0068] (Step S106) The determination unit 106A determines whether or not there are interference signals that have not been removed. If there are interference signals that have not been removed (Step S106; YES), the determination unit 106A proceeds to the process in step S107. If there are no interference signals that have not been removed (Step S106; NO), the determination unit 106A terminates the cancellation process.
[0069] (Step S107) The determination unit 106A determines the power ratio S / I n in ascending order (or S and I) n The power ratio S / I is compared with the first threshold T1 in order of the largest difference from the given value. n is less than the first threshold T1 (S / I nDetermine whether it is <T1). The determination unit 106A calculates the power ratio S / I n If it is less than the first threshold value T1 (step S107; YES), proceed to the process of step S108. The determination unit 106A calculates the power ratio S / I n If it is greater than or equal to the first threshold value T1 (step S107; NO), end the cancellation process.
[0070] (Step S108) The determination unit 106A calculates the power ratio S / I n in ascending order (or the order with the largest difference between S and I n ), and compares it with the second threshold value T2. Determine whether the power ratio S / I n is less than the second threshold value T2 (S / I n <T2). If the power ratio S / I calculated by the determination unit 106A n is less than the second threshold value T2 (step S108; YES), proceed to the process of step S109. If the power ratio S / I n is greater than or equal to the second threshold value T2 (step S108; NO), proceed to the process of step S110.
[0071] (Step S109) Based on the inter-antenna propagation information acquired from the storage unit 105, the determination unit 106A adjusts the scheduling (timing or beam combination). For example, the determination unit 106A performs interference suppression by adjusting the scheduling (such as shifting the transmission timing of the interference component, changing the transmission and reception antennas or the beam combination, and not using the beam combination where the interference signal power is large and errors are likely to occur). After the process, the determination unit 106A returns the process to step S102.
[0072] (Step S110) Based on the inter-antenna propagation information acquired from the storage unit 105, the determination unit 106A adjusts the amplitude, delay, and phase of each interference signal replica.
[0073] (Step S111) The second adjustment unit 108 performs inverse-phase synthesis in the digital signal domain of the interference signal replica with adjusted amplitude, delay, and phase on the corresponding antenna reception signal. After the process, the second adjustment unit 108 returns the process to step S106.
[0074] Thus, in this embodiment, scheduling adjustment is performed during the cancellation process in the analog signal domain. As a result, according to this embodiment, amplitude adjustment that matches the dynamic range of the desired signal becomes possible, and residual interference in the digital signal domain can be canceled with high precision, thereby improving transmission quality.
[0075] Furthermore, a portion of the wireless communication device 1 (or 1A) is configured using a processor such as a CPU (Central Processing Unit) and memory. The wireless communication device 1 (or 1A) functions, for example, as a main signal processing unit on the transmitting side, a delay adjustment unit on the transmitting side, a delay adjustment unit on the receiving side, a main signal processing unit on the receiving side, an insertion unit, a detection unit, and a measurement unit, through the execution of a program by the processor. Similarly, the delay control device 4 functions, for example, as a correction unit and a delay control unit, through the execution of a program by the processor. Note that some functions of the first communication device 2, the second communication device 3, and the delay control device 4 may be implemented using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array). The above program may be recorded on a computer-readable recording medium. Computer-readable recording media include, for example, portable media such as flexible disks, magneto-optical disks, ROMs, CD-ROMs, and semiconductor memory devices (e.g., SSDs: Solid State Drives), as well as storage devices such as hard disks and semiconductor memory devices built into computer systems. The above program may be transmitted via a telecommunications line.
[0076] Figure 8 is a schematic diagram showing an example of the hardware configuration of an information processing device applied to the embodiment. For example, some functions of the wireless communication device 1 (or 1A) may be realized by the information processing device 6, as shown in Figure 8, executing a program. The information processing device 6 includes, for example, a processor 601, a main memory 602, a communication interface 603, an auxiliary storage device 604, an input / output interface 605, and an internal bus 606. The processor 601, the main memory 602, the communication interface 603, the auxiliary storage device 604, and the input / output interface 605 are connected to each other via the internal bus 606 so as to be able to communicate with each other. The information processing device 6 may be applied to, for example, a part of a wireless communication device 1 (or 1A). In this case, for example, the first modulator 101, the first DA converter 102, the second modulator 103, the second DA converter 104, the determination unit 106, the first adjustment unit 107, the second adjustment unit 108, the AD converter 111, the second arithmetic unit 112, and the demodulation unit 113 may be configured using the processor 601, the main memory 602, and the auxiliary storage device 604. The storage unit 105 may also be configured using the main memory 702 and the auxiliary storage device 704.
[0077] In each of the embodiments described above, "base station" may be a "wireless base station," "NodeB," "eNodeB," "gNodeB," "access point," "cell," "macrocell," "small cell," "femtocell," "picocell," etc.
[0078] As described above, in each embodiment, the reduction of interference in the analog signal domain is suppressed to reduce the decrease in quantization resolution. Furthermore, in each embodiment, the determination unit 106 reduces the interference in the analog signal domain until it can be processed with high accuracy in the digital signal domain. As a result, according to each embodiment, amplitude adjustment can be made to match the dynamic range of the desired signal, and residual interference in the digital signal domain can be canceled with high precision, thereby improving transmission quality.
[0079] Although embodiments for carrying out the present invention have been described above using examples, the present invention is not limited in any way to these embodiments, and various modifications and substitutions can be made without departing from the spirit of the present invention. [Industrial applicability]
[0080] The configurations and processes of each embodiment described above can be applied, for example, to wireless communication devices, aggregation stations, transmitting devices, receiving devices, transmission devices, wireless communication systems, etc. [Explanation of Symbols]
[0081] 1,1A…Wireless communication device, 101…First modulator, 102…First DA converter, 103…Second modulator, 104…Second DA converter, 105…Storage unit, 106,106A…Determination unit, 107…First adjustment unit, 108…Second adjustment unit, 109…First calculation unit, 110…AGC, 111…AD converter, 112…Second calculation unit, 113…Demodulation unit, 11-1~11-N…Base station antenna
Claims
1. A wireless communication device that transmits multiple transmission signals and receives at least one reception signal, Using the propagation information between the antennas where interference occurs between the multiple antennas transmitting each of the aforementioned transmission signals and the antenna receiving the aforementioned reception signals, the power ratio of the uplink signal in the antenna where the interference occurs with respect to each of the interfering signals is calculated. The power ratio is compared with a first threshold, and if the power ratio is less than the first threshold, the power ratio is compared with a second threshold. When the power ratio is less than the second threshold, interference between the upper and lower links in the analog signal domain is reduced. When the power ratio is greater than or equal to the second threshold, interference between the upper and lower links in the digital signal domain is reduced. Judgment department, A wireless communication device equipped with the following features.
2. The determination unit, The power ratio is compared with a first threshold, and if the power ratio is less than the first threshold, the power ratio is compared with a second threshold. When the power ratio is less than the second threshold, the amplitude, delay, and phase of each interference signal replica are adjusted, and the adjusted interference signal replicas are combined with the received signal in reverse phase in the analog signal domain to reduce interference between the upper and lower links. When the power ratio is greater than or equal to the second threshold, the amplitude, delay, and phase of each interference signal replica are adjusted, and the adjusted interference signal replicas are combined with the received signal in reverse phase in the digital signal domain to reduce interference between the upper and lower links. The wireless communication device according to claim 1.
3. The determination unit, The power ratio is compared with a first threshold, and if the power ratio is less than the first threshold, the power ratio is compared with a second threshold. If the power ratio is less than the second threshold, the transmission and reception schedule is adjusted based on the propagation information between the antennas. When the power ratio is greater than or equal to the second threshold, the amplitude, delay, and phase of each interference signal replica are adjusted, and the adjusted interference signal replicas are combined with the received signal in reverse phase in the digital signal domain to reduce interference between the upper and lower links. The wireless communication device according to claim 1.
4. The determination unit, The process of comparing the power ratio with the first threshold and adjusting based on the comparison of the power ratio with the second threshold is repeated until high-precision processing can be achieved in the digital signal domain. The wireless communication device according to claim 1.
5. The determination unit, The power ratios are sorted in ascending order, and a comparison is made between the power ratio and the first threshold, and between the power ratio and the second threshold. The wireless communication device according to claim 1.
6. The determination unit, The aforementioned transmission and reception schedule is performed by one of the following: shifting the transmission timing of the interference signal or the transmission timing of the received signal; changing the transmitting and receiving antennas or beamsets; and avoiding the use of beamsets where the interference signal power is large and errors are certain to occur in terms of quantization resolution. The wireless communication device according to claim 3.