JP2018098562A - Communication device, control method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively suppress interference from OFDM signals which do not use a cyclic prefix or have different cyclic prefix lengths, with respect to the OFDM signals using the cyclic prefix.SOLUTION: In a wireless communication system, a first orthogonal frequency division multiplexing (OFDM) signal using a cyclic prefix and a second OFDM signal in which a cyclic prefix is not used or a cyclic prefix length is different from that of the first OFDM signal are transmitted. A communication device capable of transmitting the second OFDM signal in which a process for suppressing the interference to the first OFDM signal is performed to a partner device in the wireless communication system, receives information on delay spread of the signal to be transmitted to the partner device from the communication device, from the partner device, sets a mode to be used in the process in which interference is suppressed, on the basis of the information on the delay spread, and transmits the second OFDM signal where the process in which interference is suppressed in the set mode is performed, to the partner device.SELECTED DRAWING: Figure 7

Description

  The present invention relates to an interference control technique in a wireless communication system.

  Currently, as a next-generation mobile radio communication system, a communication system using an orthogonal frequency division multiplexing (OFDM) signal that does not use a cyclic prefix has been proposed (Non-Patent Document 1). On the other hand, at the start of introduction, a next-generation communication method signal may be transmitted on a different frequency channel in the same frequency band as a current-generation communication method signal using an OFDM signal using a cyclic prefix. is assumed. In addition, as a signal of the next generation communication method, an OFDM signal using a cyclic prefix and an OFDM signal not using a cyclic prefix or having a different cyclic prefix length may coexist in the same frequency band.

Thorsten. W et al., “5G Air Interface Designed on Universal Filtered (UF-) OFDM”, International Conference on Digital Signaling Month, 20th year, 14th International Processing. Ahmed. R, et al., “Coexistence of UF-OFDM and CP-OFDM”, IEEE Vehicular Technology Conference, May 2016

  In such a case, in the receiving apparatus, the first OFDM signal using the cyclic prefix and the second OFDM signal not using the cyclic prefix or the second OFDM signal having a cyclic prefix length different from the first OFDM signal are received simultaneously. Can be done. Here, assuming that the receiving apparatus demodulates the first OFDM signal, the receiving apparatus executes a receiving process of removing the cyclic prefix from the first OFDM signal and performing discrete Fourier transform. On the other hand, the receiving apparatus receives the second OFDM signal at the same time as the first OFDM signal, and simultaneously with the reception processing of the first OFDM signal, the first OFDM signal is also received from the second OFDM signal. The reception process is executed. At this time, if a component of the cyclic prefix time interval of the first OFDM signal is removed from the second OFDM signal, the second OFDM signal after the cyclic prefix removal loses orthogonality, and as a result, the first OFDM signal is lost. It can interfere with the OFDM signal. On the other hand, in the simplest case, it is considered that the second OFDM signal is not transmitted while the first OFDM signal is transmitted. However, this has a problem that the time interval in which the second OFDM signal can be transmitted is very limited, which is not efficient.

  The present invention has been made in view of the above problems, and an object thereof is to efficiently suppress interference from an OFDM signal that does not use a cyclic prefix to an OFDM signal that uses a cyclic prefix.

  In order to achieve the above object, a communication apparatus according to the present invention does not use a first orthogonal frequency division multiplexing (OFDM) signal and a cyclic prefix using a cyclic prefix, or uses the first OFDM signal and a cyclic prefix length. In a wireless communication system in which a second OFDM signal having a different frequency is transmitted, communication capable of transmitting the second OFDM signal, which has been subjected to processing for suppressing interference to the first OFDM signal, to a counterpart device A receiving unit configured to receive information based on a delay spread of a signal transmitted from the communication device to the counterpart device from the counterpart device; and suppressing the interference based on the information based on the delay spread. A setting means for setting the mode to be used in the process and a process for suppressing interference in the set mode are performed. Said second OFDM signal, and a transmission means for transmitting to the remote device.

  In order to achieve the above object, another communication apparatus according to the present invention includes a first orthogonal frequency division multiplexing (OFDM) signal that uses a cyclic prefix and a cyclic OFDM that does not use a cyclic prefix or the first OFDM signal. In a wireless communication system in which a second OFDM signal having a different cyclic prefix length is transmitted, the communication device receives the second OFDM signal from a counterpart device, and the delay spread of the signal transmitted from the counterpart device Identification means for identifying the transmission, transmission means for transmitting information based on the identified delay spread to the counterpart device, and the second processing subjected to processing for suppressing interference in a mode based on the information based on the delay spread Receiving means for receiving an OFDM signal from the counterpart device.

  ADVANTAGE OF THE INVENTION According to this invention, the interference from the OFDM signal which does not use a cyclic prefix with respect to the OFDM signal which uses a cyclic prefix can be suppressed efficiently.

The figure which shows the structural example of a radio | wireless communications system. The figure explaining the subject at the time of receiving the OFDM signal which uses a cyclic prefix, and the OFDM signal which does not use a cyclic prefix. The figure explaining the several mode of interference suppression processing. The figure which shows the hardware structural example of a transmitter and a receiver. The block diagram which shows the function structural example of a transmitter. The block diagram which shows the function structural example of a receiver. The figure which shows the example of the flow of the process which a transmitter performs. The figure which shows the example of the flow of the process which a receiver performs.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Configuration of wireless communication system)
FIG. 1 is a diagram illustrating a configuration example of a wireless communication system according to the present embodiment. The wireless communication system in FIG. 1 includes, as an example, two transmission devices and one reception device. This is an example, and there may be three or more transmission devices or only one transmission device, and two or more reception devices. In FIG. 1, the first transmitter transmits a first orthogonal frequency division multiplexing (OFDM) signal using a cyclic prefix (CP), and the second transmitter does not use CP or the first OFDM It is assumed that a second OFDM signal having a CP length different from that of the signal is transmitted. The receiving device is a counterpart device for communication between the first transmitting device and the second transmitting device, and simultaneously receives the first OFDM signal and the second OFDM signal. For example, one of the transmitting device and the receiving device may be a base station device and the other may be a mobile unit or a fixed terminal device, but both may be terminal devices, and the present invention is not limited to these examples.

  Here, the OFDM signal refers to all signals using carriers orthogonal to each other, and is a concept including DFT-S-OFDM (DFT spread OFDM) and the like.

  In the following description, the wireless communication system in FIG. 1 is a time synchronization system, but the present invention is not limited to this. For example, on the assumption that the second transmitter apparatus can control the second OFDM signal according to the information regarding the timing of the window for removing the CP of the first OFDM signal in the receiver apparatus, the asynchronous system is Can be used. Here, the window for removing the CP refers to a time interval in which the receiving apparatus extracts a component in the time domain to be subjected to Fourier transform.

  The first OFDM signal and the second OFDM signal can be simultaneously transmitted by frequency division multiplexing in one of frequency bands such as an 800 MHz band, a 2 GHz band, and a 3 to 4 GHz band, for example. The receiving device collectively receives signals in the same frequency band. For example, the receiving apparatus removes the CP from each of one or more symbols included in the first OFDM signal, and performs a discrete Fourier transform (DFT) on the symbols after the removal of the CP.

  At this time, the receiving apparatus may simultaneously receive the second OFDM signal in the same frequency band. In this case, since the second OFDM signal is received by being superimposed on the first OFDM signal in the time domain, CP removal, which is processing in the time domain, is also executed for the second OFDM signal. It becomes. That is, the second OFDM signal is subjected to DFT after the signal component in the section corresponding to the CP of the first OFDM signal is removed. Here, when such a signal component is removed from the second OFDM signal, the orthogonality originally secured is lost, and the frequency component of the second OFDM signal leaks into the adjacent frequency band. It may interfere with the first OFDM signal that has been separated on the axis. This is due to the discontinuity of the component of the second OFDM signal at the start timing and end timing of the window. This state is schematically shown in FIG. As shown on the left side of FIG. 2, the first OFDM signal and the second OFDM signal are transmitted without overlapping frequency components by frequency division multiplexing in the radio section. For this reason, the second OFDM signal does not interfere with the first OFDM signal in the radio section. This is because the amplitude at the start timing and end timing of the symbols of the second OFDM signal is continuous. On the other hand, as shown on the right side of FIG. 2, when the receiving apparatus removes the CP, the component of the time interval corresponding to the CP of the second OFDM signal is simultaneously removed. As a result, the amplitude of the second OFDM signal becomes discontinuous, the frequency component of the second OFDM signal spreads, and interferes with the first OFDM signal.

  In the present embodiment, in order to prevent such interference, the second transmission apparatus performs a process of generating the second OFDM signal so as to suppress the discontinuity described above. Here, it is assumed that the second OFDM signal is obtained by band-limiting the OFDM signal with a predetermined filter, and has the same time length as the first OFDM signal. Then, it is assumed that the first OFDM signal and the second OFDM signal are transmitted so as to be synchronized at the reception timing in the receiver. At this time, assuming that the start (or end) timing of the window used for CP removal in the reception processing of the first OFDM signal is a boundary between two symbols of the main wave of the first OFDM signal, the timing The amplitude of the main wave of the second OFDM signal at (0) becomes (almost) zero. Therefore, in this case, the second transmitting apparatus causes the amplitude of the second OFDM signal at the end (or start) timing of the window in the receiving process at the receiving apparatus to be sufficiently smaller than a predetermined value (almost zero). To. For example, in an asynchronous system, the reception amplitude of the second OFDM signal in the reception device may not be (substantially) zero at the start (or end) timing of the window. For this reason, the second transmission apparatus may perform signal generation so that the reception amplitude of the second OFDM signal in the reception apparatus is sufficiently smaller than a predetermined value at the end (or start) timing of the window. . That is, the second transmitting apparatus performs processing such that the amplitude of the second OFDM signal is equal to or smaller than a predetermined value at both the start and end timings of the window in the receiving process at the receiving apparatus. Thereby, even if some signal components are removed by CP removal of the first OFDM signal, continuity of the signal is ensured in the second OFDM signal, and as a result, the frequency of the second OFDM signal is increased. The amount of components leaking into adjacent frequency bands is reduced.

  When the delay wave of the second OFDM signal does not exist or is sufficiently attenuated compared to the main wave, for example, the second OFDM signal has a sufficient amplitude in the section corresponding to the CP of the first OFDM signal. By transmitting in a suppressed state, it is possible to suppress the collapse of orthogonality. On the other hand, there may actually be a delayed wave with an intensity that cannot be ignored compared to the main wave. In this case, if the second OFDM signal is transmitted while sufficiently suppressing the amplitude of the second OFDM signal in the interval corresponding to the CP time interval of the first OFDM signal, the amplitude of the delayed wave at the end of the time interval described above The amplitude difference from the start of the time interval is not sufficiently small. In order to reduce the influence of such a delayed wave, in addition to the interval corresponding to the CP time interval of the first OFDM signal, reception of the delayed wave and the main wave that can be received the latest with a significant intensity amplitude It is necessary to sufficiently suppress the amplitude of the second OFDM signal in a period corresponding to the time difference. That is, by extending the period in which the amplitude is limited by the second OFDM signal by the delay wave and shortening the length of the period in which the amplitude is not limited accordingly, even if a delay wave exists, the above-described time The reception amplitude difference of the second OFDM signal at the start and end of the section is sufficiently small.

  Here, as an example, a case will be considered in which processing for suppressing interference from the second OFDM signal to the first OFDM signal is performed on signals transmitted from a plurality of terminal apparatuses to the base station apparatus. In this case, the plurality of terminal devices receive a difference in reception time between the delayed wave and the main wave that can be received the latest with the amplitude of significant intensity in the propagation environment between each of the plurality of terminal devices and the base station device. Accordingly, it is conceivable to extend the period during which the amplitude is limited. In addition, this “delayed wave that can be received the latest with the amplitude of significant intensity in the propagation environment between each of the plurality of terminal apparatuses and the base station apparatus” is based on, for example, a statistical value of delay spread in advance. Can be set. However, the propagation environment between each of the plurality of terminal devices and the base station device is assumed to be different, and the reception time difference between the delayed wave and the main wave that can be received the latest with a significant intensity amplitude is also the propagation environment. Can vary depending on the difference. For this reason, the terminal device having a short reception time difference between the delayed wave and the main wave described above with respect to the signal received by the base station device is transmitted by itself due to the influence of another terminal device having a long reception time difference. In an OFDM signal, the amplitude of an unnecessarily long period may be limited. Similarly, if the amplitude of the second OFDM signal is limited by a preset value, the signal from many terminal devices (possibly all terminal devices) can be received the latest with a significant intensity amplitude. There may be a case where the reception time difference between the delay wave and the main wave is smaller than the preset value. Also in this case, the terminal device may limit the amplitude of the second OFDM signal in an unnecessarily long period. Then, when the amplitude limiting period is unnecessarily prolonged, the frequency utilization efficiency of the entire system may be deteriorated.

  For this reason, in the present embodiment, the second transmission device receives information on the delay spread of the signal transmitted from the second transmission device to the reception device from the reception device. The delay spread here may be a time difference from the arrival timing of the first radio wave such as the main wave to the arrival timing of the last delay wave received at a predetermined power or higher for a certain radio signal. The information related to the delay spread can be information specifying the time difference. For example, the receiving device identifies the delay spread based on the reference signal transmitted from the second transmitting device, and transmits information regarding the identified delay spread to the second transmitting device.

  For example, the second transmitter sets a time interval in which the amplitude of the second OFDM signal is equal to or less than a predetermined value to a time interval corresponding to the delay spread, and controls the amplitude of the second OFDM signal to be transmitted. This suppresses interference. That is, the second transmission apparatus transmits the second OFDM signal so that the amplitude difference of the second OFDM signal received by the reception apparatus is equal to or less than a predetermined threshold at the start and end timings of the window. The amplitude is adjusted, and the time interval in which the amplitude is not adjusted is lengthened. The second transmission device can prepare a plurality of modes related to the interference suppression processing. These modes correspond to different delay spreads, and the time interval in which the amplitude is less than or equal to the predetermined value becomes longer as the delay spread becomes larger, and the time interval in which the amplitude becomes less than or equal to the predetermined value becomes shorter as the delay spread becomes smaller. It can be a phased mode. An example of this interference suppression processing mode is shown in FIG. FIG. 3 shows an example of a three-stage mode. In the example of FIG. 3, for the longest delay spread, mode 1 in which the period during which the amplitude is suppressed to a predetermined value or less is set long, and for the shortest delay spread, the period in which the amplitude is suppressed to a predetermined value or less. There is a mode 3 that is set short and a mode 2 that is in between. Each mode corresponds to the delay spread so that the second OFDM signal has the amplitude difference at the start and end timings of the above-mentioned window at the receiving apparatus that has received the second OFDM signal is equal to or less than a predetermined value. It is attached. The second transmitter selects a mode corresponding to the delay spread based on the received information regarding the delay spread. Thereby, in the receiving apparatus, interference of the second OFDM signal due to the Fourier transform window accompanying reception of the first OFDM signal is suppressed.

  Note that the receiving apparatus may notify the second transmitting apparatus of information specifying the interference suppression processing mode as information on the delay spread described above. That is, the receiving apparatus can specify the mode of interference suppression processing corresponding to the delay spread for the signal from the second transmitting apparatus, and can notify the specified mode to the second transmitting apparatus. At this time, the receiving apparatus may determine or hold the correspondence relationship between the mode and the delay spread, or may receive information associating the delay spread with the mode from the second transmitting apparatus. You may receive and acquire in advance. In addition, when determining the correspondence between the mode and the delay spread by itself, the receiving apparatus can select one of a plurality of correspondence candidates determined in advance. Each of the plurality of correspondence candidates is configured such that at least one of the delay spread range corresponding to each mode and the period in which the amplitude is limited differ from the other candidates. For example, there may be a correspondence candidate as shown in FIG. 3 and another correspondence candidate including an intermediate mode between mode 1 and mode 2 and an intermediate mode between mode 2 and mode 3 in FIG. . Further, the amplitude is limited corresponding to a mode in which the period during which the amplitude is limited is set to be longer corresponding to a range where the delay spread is larger than that in mode 1 in FIG. There may be another candidate including a mode in which the period to be set is shorter. When the receiving device receives the notification of the above correspondence from the second transmitting device, the second transmitting device may make this notification using a broadcast signal, and the receiving device is the destination. This notification may be performed using an individual signal.

  In addition, although this embodiment demonstrated the example in case a receiver receives a 1st OFDM signal and a 2nd OFDM signal, it is not restricted to this. That is, the first receiving device that receives the first OFDM signal and the second receiving device that receives the second OFDM signal may exist separately. In this case, the second transmission device receives the information about the delay spread from the first reception device, sets the mode of the interference suppression processing based on the information about the delay spread, and generates the information based on the mode. The second OFDM signal is transmitted to the second receiving device.

  Hereinafter, the configuration of the communication apparatus having the function of the second transmission apparatus or the reception apparatus and the flow of processing will be described in detail.

(Hardware configuration)
FIG. 4 shows a hardware configuration example of the above-described second transmission device (hereinafter simply referred to as “transmission device”) or a communication device having the function of a reception device. For example, the communication apparatus has a hardware configuration as shown in FIG. 4, and includes, for example, a CPU 401, a ROM 402, a RAM 403, an external storage device 404, and a communication circuit 405. In the communication device, for example, the CPU 401 executes a program that realizes each function of the transmission device or the reception device as described above, which is recorded in any of the ROM 402, the RAM 403, and the external storage device 404. Here, the CPU 401 is an example of a processor, and may be replaced by another processor such as an ASIC (application-specific integrated circuit), or may be replaced by a reconfigurable processor such as an FPGA (field programmable gate array). Also good.

  And a communication apparatus controls the communication circuit 405 by CPU401, for example, and communicates with another apparatus. Note that the communication circuit 405 can perform at least one of transmission and reception of an OFDM signal that does not use a CP. In some cases, the communication circuit 405 transmits and receives an OFDM signal that uses a CP or a signal of another wireless communication method. It may be configured to perform at least one of. Further, the communication circuit 405 may be able to transmit and receive signals not only in one frequency band but also in a plurality of frequency bands. For example, both a cellular communication system and a wireless LAN communication system may be used. . Further, the communication circuit 405 may be configured to perform wired communication. In the configuration of FIG. 4, the communication apparatus is schematically illustrated as having one communication circuit 405, but is not limited thereto. For example, the communication device may include a first communication circuit for cellular communication and a second communication circuit for wireless LAN communication. In addition, when the communication device itself is a base station device, for example, in addition to a communication circuit for wireless communication with the terminal device, the communication device performs wired communication or wireless communication for communication with other base station devices. A communication circuit may be included.

  Note that the communication device may include dedicated hardware that executes each function, or may execute other portions by a computer that executes a part of the hardware and operates the program. All functions of the communication device may be executed by a computer and a program.

(Functional configuration)
FIG. 5 is a diagram illustrating a functional configuration example of the transmission apparatus according to the present embodiment. In one example, the transmission apparatus includes a transmission unit 501, a reception unit 502, an information acquisition unit 503, and a setting unit 504. Note that the transmission apparatus may include a mode information notification unit 505. Note that the transmission device may be a base station device or a terminal device in a cellular radio communication system. In addition, the transmission device may have functions (not shown) such as various functions that an information processing device including the transmission device has.

  The transmission unit 501 transmits the second OFDM signal generated by applying the interference suppression processing based on the mode set by the setting unit 504 described later to the reception device. Note that the transmission unit 501 may generate and transmit the second OFDM signal without applying the interference suppression process, for example, when the amount of interference with the first OFDM signal is sufficiently small. For example, when notified from the receiving apparatus that the interference suppression process does not need to be applied from the receiving apparatus, the transmitting unit 501 generates and transmits the second OFDM signal without applying the interference suppressing process. In addition, when the mode information notification unit 505 is configured to notify the reception device of information associating the delay spread with the mode to be used, the transmission unit 501 transmits the information to the reception device as a radio signal. Can be configured as follows. Note that the transmission unit 501 can transmit the information generated by the mode information notification unit 505 using, for example, a broadcast signal or an individual signal destined for the reception device. The transmission unit 501 includes, for example, an antenna, a circuit used for outputting a radio signal via the antenna, and a circuit for wired communication as necessary.

  The receiving unit 502 receives a wireless signal transmitted by the receiving device. The radio signal received by the reception unit 502 may be a second OFDM signal or a signal different from the second OFDM signal such as the first OFDM signal. The receiving unit 502 includes, for example, an antenna, a circuit for processing a radio signal received via the antenna and extracting data, and a circuit for wired communication as necessary. Note that the transmission unit 501 and the reception unit 502 can share one or more antennas and circuits.

  The information acquisition unit 503 acquires, for example, information on the delay spread related to the signal transmitted from the transmission device from the reception device via the reception unit 502. Note that the information on delay spread may be a value itself indicating the magnitude of delay spread, or information indicating the mode of interference suppression processing to be used, selected according to the magnitude of delay spread. May be.

  When the information acquisition unit 503 receives information indicating a delay spread value, the setting unit 504 determines a mode of interference suppression processing to be applied to the second OFDM signal transmitted by the transmission unit 501 based on the value. Then, the transmission unit 501 is set to use the mode. In this case, for example, in the receiving apparatus, the setting unit 503 sets the second OFDM signal reception amplitude difference at the start and end timings of the window used for demodulation of the first OFDM signal to be equal to or less than a predetermined threshold. The transmission amplitude of the OFDM signal of 2 is adjusted. At this time, the setting unit 503 determines the mode so that the time interval in which the amplitude is not adjusted is as long as possible. Note that the setting unit 503 can make this determination by preparing in advance a plurality of modes as shown in FIG. 3, for example, and selecting one of the plurality of modes based on the delay spread value. On the other hand, for example, when the information acquisition unit 503 acquires information on the mode selected by the reception device corresponding to the magnitude of the delay spread, the setting unit 504 transmits the acquired mode by the transmission unit 501. 2 is set as an interference suppression processing mode to be applied to the second OFDM signal.

  The mode information notification unit 505 notifies the receiving apparatus of information that associates the delay spread value with the mode. For example, the mode information notification unit 505 notifies the reception apparatus of information indicating the range of delay spread values corresponding to each of the modes 1 to 3 shown in FIG. This information may be information for causing the receiving apparatus to transmit information specifying a mode as information regarding delay spread. In addition, when the information regarding the delay spread is information indicating the delay spread value itself or information used for deriving the value, the mode information is notified when the receiving apparatus does not select the mode. The unit 505 can be omitted.

  FIG. 6 is a diagram illustrating a functional configuration example of the receiving device according to the present embodiment. In one example, the receiving apparatus includes a transmitting unit 601, a receiving unit 602, a delay spread specifying unit 603, and an information notification unit 604. Note that the receiving apparatus may include a mode information acquisition unit 605 as necessary. The receiving device can be a base station device or a terminal device in a cellular radio communication system. In addition, the receiving device may have functions (not shown) such as various functions that an information processing device including the receiving device has.

  The transmission unit 601 can transmit a radio signal to at least the transmission device, and the reception unit 602 can receive at least a radio signal from the transmission device. Note that the receiving unit 602 can receive not only the second OFDM signal but also the first OFDM signal. Further, the transmission unit 601 may be capable of transmitting not only the second OFDM signal but also the first OFDM signal. In addition, the transmission unit 601 and the reception unit 602 may be able to transmit / receive other types of signals for control signals, for example. The transmission unit 601 includes, for example, an antenna, a circuit used for outputting a radio signal via the antenna, and a circuit for wired communication as necessary. The receiving unit 602 includes, for example, an antenna, a circuit for processing a wireless signal received via the antenna and extracting data, and a circuit for wired communication as necessary. Note that the transmission unit 601 and the reception unit 602 can share one or more antennas and circuits.

  The delay spread specifying unit 603 specifies the delay spread for the signal transmitted from the transmission device via the receiving unit 602. The delay spread specifying unit 603 specifies the delay spread related to the transmission path between the transmission device and the reception device, for example, based on a predetermined reference signal transmitted by the transmission device. The information notification unit 604 notifies the transmission apparatus of information related to the delay spread specified by the delay spread specifying unit 603 via the transmission unit 601. The mode information acquisition unit 605 acquires information that associates the delay spread value with the mode from the transmission apparatus. When the mode information acquisition unit 605 acquires information that associates the value of the delay spread with the mode, the information notification unit 604 selects a mode to be used based on the delay spread specified by the delay spread specifying unit 603. Select and notify the transmitter. Note that the information notification unit 604 may notify the transmission apparatus of information indicating the delay spread value itself or information used for deriving the value as information on the delay spread. Thus, when the receiving apparatus does not select a mode, the mode information acquisition unit 605 can be omitted.

(Process flow)
Next, an example of the flow of processing executed by the transmission device and the reception device will be described with reference to FIGS. FIG. 7 shows an example of the flow of processing executed by the transmitting apparatus, and FIG. 8 shows an example of the flow of processing executed by the receiving apparatus.

  First, the transmitting apparatus transmits information associating the delay spread and the interference suppression processing mode to the receiving apparatus (S701), and the receiving apparatus receives the information (S801). Here, the transmitting device can transmit this information, for example, using a broadcast signal or using an individual signal destined for the receiving device. If the receiving apparatus does not select a mode, the processing in S701 and S801 can be omitted. Further, even when the receiving apparatus selects a mode, if the relationship between the delay spread and the interference suppression processing mode is known, it is not necessary to acquire the above information again, and therefore The processing of S701 and S801 can be omitted.

  The transmitting device periodically transmits a reference signal (S702), and the receiving device specifies a delay spread based on the reference signal (S802). The receiving apparatus can specify the time difference from the timing at which one signal is first received at a predetermined power or higher to the timing at which it is last received as a delay spread. Then, the receiving device transmits information regarding the specified delay spread to the transmitting device (S803). Here, when the receiving apparatus knows the relationship between the delay spread and the interference suppression processing mode (for example, through the process of S801), the receiving apparatus selects the mode to be used based on the delay spread specified in S802, and the mode is selected. Can be transmitted to the transmission device as information on delay spread. Upon receiving the information on delay spread (S703), the transmission apparatus sets a mode for interference suppression processing based on the received information, and generates a second OFDM signal to which the interference suppression processing in that mode is applied. (S704). When a value indicating the magnitude of delay spread is notified, the transmission apparatus selects an interference suppression processing mode according to the value, and sets the interference suppression processing mode. On the other hand, when a value indicating the mode of the interference suppression process is notified, the transmission device sets the mode of the interference suppression process to be the notified mode. Thereafter, the transmission apparatus transmits the generated second OFDM signal (S705), and the reception apparatus receives the second OFDM signal to which the interference suppression process is applied (S804).

  As described above, in the present embodiment, the delay spread related to the second OFDM signal transmitted from the transmission device to the reception device is specified, and the interference suppression processing mode suitable for the delay spread is set. As a result, the transmitting apparatus does not limit the amplitude of the second OFDM signal in an unnecessarily long period, and therefore it is possible to suppress deterioration in frequency utilization efficiency of the entire system.

Claims (15)

A wireless communication system in which a first orthogonal frequency division multiplexing (OFDM) signal that uses a cyclic prefix and a second OFDM signal that does not use a cyclic prefix or that has a different cyclic prefix length from the first OFDM signal A communication apparatus capable of transmitting the second OFDM signal, which has been subjected to processing for suppressing interference to the first OFDM signal, to a partner apparatus,
Obtaining means for obtaining information on delay spread of a signal transmitted from the communication device to the counterpart device from the counterpart device;
Setting means for setting a mode to be used in the processing for suppressing the interference based on the information on the delay spread;
Transmitting means for transmitting the second OFDM signal, which has been subjected to processing for suppressing interference in a set mode, to the counterpart device;
A communication apparatus comprising: The setting means sets a time interval in which the amplitude of the second OFDM signal is suppressed to a predetermined value or less according to the mode.
The communication apparatus according to claim 1. The information on the delay spread is information specifying a mode associated with the delay spread,
The setting means sets the mode to be used to a designated mode;
The communication apparatus according to claim 1 or 2, wherein A notification means for notifying the counterpart device of information associating the delay spread with a mode of processing for suppressing the interference;
The communication apparatus according to claim 3. The notification means notifies the partner apparatus of information that associates the delay spread with a mode of processing for suppressing the interference, using a broadcast signal.
The communication apparatus according to claim 4. The notification means notifies the partner device of information relating the delay spread and the processing mode for suppressing the interference, using an individual signal destined for the partner device.
The communication apparatus according to claim 4. A wireless communication system in which a first orthogonal frequency division multiplexing (OFDM) signal that uses a cyclic prefix and a second OFDM signal that does not use a cyclic prefix or that has a different cyclic prefix length from the first OFDM signal A communication device for receiving the second OFDM signal from the counterpart device,
A specifying means for specifying a delay spread of a signal transmitted from the counterpart device;
Notification means for notifying the counterpart device of information relating to the specified delay spread;
Receiving means for receiving, from the counterpart device, the second OFDM signal that has been subjected to processing for suppressing interference with the first OFDM signal in a mode based on information related to the delay spread;
A communication apparatus comprising: The notifying means notifies information specifying a mode associated with the delay spread as information on the delay spread.
The communication apparatus according to claim 7. Further comprising acquisition means for acquiring information relating the delay spread and the mode of processing for suppressing the interference from the counterpart device;
The communication apparatus according to claim 8. The acquisition means acquires information that associates the delay spread and a mode of processing for suppressing the interference with a broadcast signal transmitted from the counterpart device,
The communication apparatus according to claim 9. The acquisition means acquires information associating the delay spread and a mode of processing for suppressing the interference with an individual signal transmitted from the counterpart device,
The communication apparatus according to claim 9. A wireless communication system in which a first orthogonal frequency division multiplexing (OFDM) signal that uses a cyclic prefix and a second OFDM signal that does not use a cyclic prefix or that has a different cyclic prefix length from the first OFDM signal A method of controlling a communication apparatus capable of transmitting the second OFDM signal, which has been subjected to processing for suppressing interference to the first OFDM signal, to a partner apparatus,
An acquisition unit that acquires information on a delay spread of a signal transmitted from the communication device to the counterpart device from the counterpart device;
A setting step in which a setting unit sets a mode to be used in the process of suppressing the interference based on the information on the delay spread;
A transmission step in which the transmission means transmits the second OFDM signal subjected to the processing for suppressing interference in the set mode to the counterpart device;
A control method characterized by comprising: A wireless communication system in which a first orthogonal frequency division multiplexing (OFDM) signal that uses a cyclic prefix and a second OFDM signal that does not use a cyclic prefix or that has a different cyclic prefix length from the first OFDM signal A method of controlling a communication device for receiving the second OFDM signal from a counterpart device, comprising:
A specifying step of specifying a delay spread of a signal transmitted from the counterpart device;
A notification step of notifying the counterpart device of information relating to the identified delay spread;
A receiving step for receiving from the counterpart device the second OFDM signal that has been subjected to a process for suppressing interference on the first OFDM signal in a mode based on information related to the delay spread;
A control method characterized by comprising: A wireless communication system in which a first orthogonal frequency division multiplexing (OFDM) signal that uses a cyclic prefix and a second OFDM signal that does not use a cyclic prefix or that has a different cyclic prefix length from the first OFDM signal In the computer provided in the communication apparatus capable of transmitting the second OFDM signal, which has been subjected to the process of suppressing the interference to the first OFDM signal, to the counterpart apparatus,
From the counterpart device, to obtain information on the delay spread of the signal transmitted from the communication device to the counterpart device,
Based on the information on the delay spread, the mode used in the processing for suppressing the interference is set,
Causing the second OFDM signal that has been subjected to processing to suppress interference in a set mode to be transmitted to the counterpart device;
Program for. A wireless communication system in which a first orthogonal frequency division multiplexing (OFDM) signal that uses a cyclic prefix and a second OFDM signal that does not use a cyclic prefix or that has a different cyclic prefix length from the first OFDM signal In the computer provided in the communication device for receiving the second OFDM signal from the counterpart device,
Identify the delay spread of the signal transmitted from the counterpart device,
Notifying the partner device of information regarding the specified delay spread,
Receiving the second OFDM signal, which has been subjected to a process for suppressing interference with the first OFDM signal in a mode based on information on the delay spread, from the counterpart device;
Program for.

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