JP6435192B2 - Distributed antenna device and interference control method - Google Patents

Description

  The present invention relates to a distributed antenna apparatus and interference control technology used in a distributed antenna system.

  In order to strengthen indoor and outdoor high-speed packet communication areas, a distributed antenna system (hereinafter referred to as “DAS”) has been studied. The DAS is an integrated system in which a plurality of antenna devices or antenna units are distributed in an area spatially separated from a base station, and transmission / reception signals are collectively processed in the base station.

  There is an in-building mobile communication system (IMCS) as DAS indoor base station equipment. In IMCS, an optical transmission device called Radio on Fiber (RoF) is used. The RoF is a device that relays an RF (radio frequency) signal of a base station via an optical fiber. The RoF is a base unit (referred to as “base unit” in the following description) and an antenna unit (in the following description, “ It is referred to as a “slave”. One or more child devices are connected to the parent device, and each forms a wireless communication area.

  In RoF, the handset is arranged at various positions in the indoor facility. RoF has a delay correction function for adding an arbitrary delay amount to an optical transmission line section in order to determine which slave unit is under the control of a mobile station depending on the transmission time of the optical transmission line. This delay correction function can also be used for the purpose of setting (adding) the delay amount of each child device so as to be equal to the maximum delay amount between the parent and child devices. (Hereinafter, this delay correction is referred to as “delay correction control”, and the function for performing the control is referred to as “delay correction function”).

  Also, in the LTE system, uplink signals of different UEs received at the base station are subjected to FFT (Fast Fourier Transformation) and demodulated in a lump, but the propagation distance of the radio section differs for each UE, and the reception timing of the uplink signals is different. If it differs greatly for each UE, the base station cannot perform FFT at a desired timing. Therefore, in order to adjust the reception timing, the base station measures the difference between the actual uplink signal reception timing and the desired uplink signal reception timing, instructs the difference to the UE, and performs control to advance the transmission timing. (Hereinafter referred to as “time alignment control”, and a function for performing the control is referred to as “time alignment function”). Further, the advance time of the uplink signal of the UE by time alignment control is defined as a timing advance value.

Yoshihisa Kishiyama, 4 others, "Heterogeneous network capacity expansion technology in the advancement of LTE / LTE-Advanced", [online], [December 1, 2014], Internet (https://www.nttdocomo.co. jp / corporate / technology / rd / technical_journal / bn / vol21_2 / 010.html)

  In IMCS, transmission quality may deteriorate due to uplink interference from other systems such as neighboring macro base stations.

  For example, as shown in FIG. 1A, when a mobile station or a user terminal (UE: User Equipment) 20 wirelessly accesses a handset 30 arranged in the wireless front end of the DAS 10, one handset 30 is covered. The radius of the DAS area 11 is small and the power output of the UE 20 is also low. Therefore, the uplink signal transmitted from the UE 20 to the slave unit 30 is unlikely to become an uplink interference source for the base station (for example, the macro base station) 100 of another system adjacent to the DAS area 11.

  However, as shown in FIG. 1B, the radius of the service area 101 of the macro base station 100 is large, and the power output of the UE 200 located in the macro base station 100 is high. Therefore, the uplink signal transmitted by the UE 200 becomes an uplink interference source for the DAS 10. At this time, the signal wirelessly received by the slave unit 30 is relayed by wire by the master unit 40 and transmitted to the DAS base station apparatus 50. However, transmission quality deteriorates due to uplink interference in the radio section. .

  Transmission quality degradation due to uplink interference can occur in frequency division duplex (FDD), but in particular, all uplink signals use the same frequency for time division duplex (TDD) systems. In this case, it becomes more prominent.

  The time alignment control is originally a technique of adjusting the length of a cyclic prefix (hereinafter abbreviated as “CP”) at a base station in SC-FDMA (Single Carrier Frequency-Division Multiple Access), and reduces interference. It is not a technique. Therefore, even if time alignment control is performed on an uplink signal by DAS, interference can be a problem.

  Accordingly, an object of the present invention is to reduce the influence of uplink interference in DAS.

  In order to solve the above-described problem, in the present invention, the delay correction function is used to intentionally (virtually) increase the transmission distance between the slave unit and the master unit. The reception timing of the desired uplink signal is set earlier than the reception timing of the interference signal to reduce the influence of uplink interference. Here, in the delay correction function, an amount of delay correction sufficient to make the reception timing of the desired uplink signal earlier than the reception timing of the interference signal is added to the transmission path.

Specifically, the distributed antenna device used in the distributed antenna system is
A receiver for receiving an uplink desired signal from a mobile station;
A delay correction unit that adds a delay amount to the uplink desired signal from the mobile station and makes the reception timing of the uplink desired signal earlier than the reception timing of the uplink interference signal by time alignment control; It is characterized by.

  The distributed antenna device may be realized only by the slave unit, or the distributed antenna device may be configured by combining the slave unit and the master unit. In addition, the delay correction unit in the distributed antenna system is included in either the slave unit, the master unit, or both.

  The influence of uplink interference from other systems on the distributed antenna system (DAS) can be avoided. As a result, channel estimation accuracy, reception quality such as SINR, and UE-base station synchronization accuracy can be improved.

It is a figure for demonstrating the problem of the uplink interference in a distributed antenna system (DAS). It is a figure which shows the basic concept of the delay correction | amendment of embodiment. It is a figure which shows the basic concept of the delay correction | amendment of embodiment. It is a figure explaining the calculation method of delay correction amount. It is a flowchart of the delay correction method of the embodiment. It is a figure explaining the case where the uplink interference signal is received within the guard period section in step S101 of FIG. It is a figure explaining step S103 of FIG. It is a figure explaining step S105 of FIG. It is a figure explaining the process of step S107 when an uplink interference signal is received within a guard period. It is a figure explaining the case where an uplink interference signal is not received within a guard period section by step S101 of FIG. It is a figure explaining the process of step S107 when an uplink interference signal is not received within a guard period area. It is a figure which shows the structural example of the distributed antenna apparatus of embodiment. It is a figure which shows another structural example of the distributed antenna apparatus of embodiment. It is a figure which shows another structural example of the distributed antenna apparatus of embodiment. It is a figure explaining the effect of the channel estimation accuracy improvement by delay correction of an embodiment. It is a figure which shows the example of arrangement | positioning of the reference signal for a demodulation (DMRS). It is a figure which shows a special sub-frame configuration. It is a figure explaining the SINR improvement effect by delay correction of an embodiment. It is a figure explaining the synchronous performance improvement effect by delay correction of an embodiment. It is a figure explaining the effect of delay amendment of an embodiment.

In the DAS 10, a large number of slave units 30 are connected to a master unit 40 as a totaling station or a relay station by optical fibers or the like. In order to match the reception timing of uplink signals from a plurality of UEs, the uplink transmission timing of each UE is controlled based on a one-way propagation delay (STD: Single Trip Delay) between the UE and the DAS base station apparatus 50. . This control is called time alignment (TA) control because the transmission timing of the UE is advanced to match the reception timing at the DAS base station apparatus 50 in order to compensate for a delay in reception timing.
Further, the DAS 10 is equipped with a delay correction function for arbitrarily adjusting the transmission delay time in the optical transmission line section. Conventional delay correction control is performed in order to compensate for variations among optical transmission lines. In contrast, in the embodiment, a delay correction function is used to intentionally (excessively) add a delay amount to the optical transmission line section. Accordingly, the time alignment function causes the UE to advance the transmission timing of the uplink signal, and causes the DAS base station 50 to receive the uplink desired signal before the interference signal. Such delay correction combining the delay correction function for preventing interference and the time alignment function of the present invention is referred to as “DAS delay correction” for convenience.

  In the present embodiment, the DAS delay correction in the DAS 10 makes the reception timing of the uplink desired signal in the base station earlier than the reception timing of the uplink interference signal, thereby obtaining an interference-free uplink reception signal. By calculating the delay correction amount so that the uplink signal from the UE 20 is received earlier than the interference signal and adding this to the optical transmission line section, the transmission timing of the UE 20 is advanced, and the uplink interference from other systems. To improve uplink transmission quality. In this specification and drawings, “no interference” does not mean that noise or interference is completely zero, but means that there is no interference or a level of interference that hinders channel estimation for a desired signal. It is used in.

2 and 3 are diagrams for explaining a basic concept of delay correction according to the embodiment. Despite the implementation of the time alignment function or the conventional delay correction function aimed at compensating for variations in transmission path length, the reception timing of the interference signal itself received by the DAS base station 50 cannot be controlled. Therefore, the time relationship between the uplink desired signal and the uplink interference signal is the following two patterns.
(1) When the reception timing of the desired signal is earlier than the interference signal or when receiving simultaneously
(2) When the reception timing of the desired signal is later than the interference signal.

  FIG. 2 shows delay correction when the reception timing of the uplink desired signal is earlier than the reception timing of the interference signal (or in the case of simultaneous reception). As schematically shown in FIG. 2A, in the slave unit 30, the desired signal from the UE 20 (indicated as “slave unit connection terminal” in the figure) 20 connected to the slave unit 30 is transmitted to another system. It is received at an earlier timing (or simultaneously) than an interference signal transmitted by UE 200 connected to (for example, macro base station 100). However, even if the reception timing is early (or at the same time), there may be a case where sufficient SINR cannot be obtained or channel estimation cannot be performed with high accuracy. Therefore, in order to obtain a substantially no-interference state in the uplink, a delay correction amount A for preventing or reducing interference is calculated and added.

  The delay correction amount A is a correction amount intentionally (excessively) added by DAS delay correction in order to prevent uplink interference. By adding the delay correction amount A, as shown in FIG. 2B, the slave unit 30 can receive an uplink desired signal without interference. The calculated delay correction amount A is added to the wired section, and the DAS base station 50 notifies the UE 20 of the advance transmission timing. The UE 20 first transmits an uplink signal at a timing when the delay correction amount A for avoiding interference is taken into account.

  FIG. 3 shows a case where the reception timing of the uplink desired signal is later than the reception timing of the interference signal. As schematically shown in FIG. 3A, in the slave unit 30, the desired signal from the UE 30 connected to the slave unit 30 (denoted as “slave unit connection terminal” in the figure) is transmitted to another system. It is received at a timing later than the interference signal transmitted by UE 200 connected to (for example, macro base station 100).

  In this case, as shown in FIG. 3B, first, a delay correction amount B is added so that the uplink desired signal from the UE 30 has the same reception timing as the uplink interference signal (delay correction control). The delay correction amount B corresponds to the difference between the reception timings of the interference signal and the reception signal.

  Next, as shown in FIG. 3C, a delay correction amount A is added to obtain a non-interference signal, and the total delay correction amount is A + B. The delay correction amount A + B is added to the wired section. The DAS base station 50 sends an advance transmission instruction to the UE 20 based on the delay correction amount A + B. The UE 20 transmits an uplink signal at a first-out timing in which the delay correction amount A + B is added.

  FIG. 4 is a diagram showing the delay correction of FIGS. 2 and 3 more specifically. In the embodiment, delay correction for interference prevention is performed using a guard period (GP) of a special subframe in the TDD system. The special subframe (S) is a frame for switching from the transmission section (D) of the downlink subframe to the transmission section (U) of the uplink subframe, and includes a downlink pilot time slot (DwPTS) and a guard period ( GP) and uplink pilot time slot (UpPTS). DwPTS is an extension area of downlink data, UpPTS is an extension area of uplink data, and GP is not used in the downlink section or the uplink section. Since the subunit | mobile_unit 30 can receive an uplink signal from UpPTS, when there is no uplink interference signal in the GP section, the desired signal is received at the same time or earlier than the interference signal. In this case, by adding the delay correction amount A to the wired section as in FIG. 2, channel estimation using a low-interference signal becomes possible.

  On the other hand, as shown in FIG. 4, when there is an uplink interference signal in the GP section, the interference signal is received before the desired signal. In this case, similarly to FIG. 3, a delay correction amount B corresponding to the difference between the reception start time of the interference signal and the end time t2 of the GP section is added, and a delay correction amount A for ensuring a non-interference state is further added. Is done. By adding the delay correction amount A + B, the uplink signal from the UE 20 is received at a timing t1 earlier than the reception of the interference signal, and a non-interference section can be obtained.

  In order to calculate the delay correction amount B, the detector is activated at the start of GP. Since the GP length is known in advance, the difference between the GP length and the detection time is calculated as the delay correction amount B by measuring the detection time, that is, the time from when the detector is activated until the upstream interference signal is detected. Can do.

  FIG. 5 shows a control flow in the distributed antenna apparatus (the slave unit 30 or the master unit 40) of the embodiment. The distributed antenna device may be realized by the slave unit 30. Or you may comprise a distributed antenna apparatus in cooperation with the subunit | mobile_unit 30 and the main | base station 40. FIG. The distributed antenna device activates the detector every time the GP section starts, and determines whether there is an uplink interference signal in the GP section (S101). The uplink interference signal is, for example, an uplink transmission signal by the UE 200 that is connected to the adjacent macro base station 100. When there is an uplink interference signal in the GP section, the time from the start of reception of the uplink interference signal to the end of the GP section is measured as a delay correction amount B (S103), and the delay correction amount B is added to the wired section (S105). ). Further, a predetermined delay correction amount A is added to the wired section (S107). As a result, the total delay correction amount added by the DAS delay correction to avoid interference is A + B.

  If there is no uplink interference signal in the GP section, the process jumps to step S107, and a predetermined delay correction amount A is added to the wired section by DAS delay correction. By this method, the UE 20 can transmit the uplink signal in advance at a timing avoiding the influence of interference from other systems.

  FIG. 6 is a diagram illustrating processing when an uplink interference signal is received in the GP section in step S101 of FIG. The subunit | mobile_unit 30 used by DAS10 is installed in each floor of facilities, such as a building, for example as a radio | wireless front end antenna unit, and is connected with the main | base station 40 via the optical cable. Base unit 40 is installed, for example, in a core network (CN) building or the like, and relays signals from a plurality of handset units 30 to DAS base station apparatus 50. Base unit 40 and DAS base station apparatus 50 are connected, for example, via an RF (high frequency) cable.

  A service area 101 of another system (macro base station 100) is located adjacent to the DAS area 11 covered by the slave unit 30. When another UE 200 located in the macro base station 100 is communicating at the cell edge of the macro base station 100, the transmission signal of the UE 200 becomes an interference signal for the uplink of the DAS 10, and the slave unit 30 transmits the uplink interference signal in the GP section. Is detected.

  FIG. 7 is a diagram illustrating step S103 in FIG. When the uplink interference signal is detected in the GP section, the slave unit 30 or the master unit 40 calculates the delay correction amount B from the measurement time by the detector. As described above, the delay correction amount B corresponds to the time from the start of interference signal reception to the end of the GP section. The slave unit 30 or the master unit 40 calculates the delay correction amount B by subtracting the detection time from the length of the known GP section.

  FIG. 8 is a diagram illustrating step S105 in FIG. The subunit | mobile_unit 30 or the main | base station 40 which comprises a distributed antenna apparatus adds the delay correction amount B to the wired area of DAS10. By adding the delay correction amount B, the reception timing of the desired signal from the UE 20 can be advanced to the same level as the reception timing of the uplink interference signal, but this alone is insufficient for avoiding interference.

  FIG. 9 is a diagram for explaining the processing in step S107 when an uplink interference signal is received within the GP section. In addition to the delay correction amount B, the slave unit 30 or the base unit 40 also adds the delay correction amount A to the wired section in order to secure a non-interference section. Due to the time alignment function of the DAS 10, the uplink signal transmission timing of the UE 20 is intentionally advanced by a time corresponding to the delay correction amount A + B.

  FIG. 10 is a diagram for explaining a case where an uplink interference signal is not received within the guard period in step S101 of FIG. The subunit | mobile_unit 30 can receive the uplink signal from UE20 from the start area of UpPTS, Therefore The reception of a desired signal is earlier than reception of an interference signal. In this case, as shown in FIG. 11, only the delay correction amount A is added to the wired section in S107.

  In FIG. 11, by adding the delay correction amount A to the wired section, the transmission timing of the UE 20 is further advanced by an amount corresponding to the delay correction amount A. As a result, a sufficiently low interference interval is ensured, and degradation of uplink transmission quality can be prevented.

  12A to 12C are schematic configuration diagrams of the distributed antenna device. In FIG. 12A, the slave unit 30 constitutes a distributed antenna device, and in FIG. 12B, the slave unit 30 and the master unit 40 cooperate to constitute the distributed antenna device 60. In FIG. 12A, the slave unit 30 includes a radio signal transmission / reception unit 35, a timer group 36, an optical signal transmission / reception unit 37, and a delay correction unit 31. The radio signal transmission / reception unit 35 performs radio communication with the UE 20 of the slave unit 30 by the TDD method. The optical signal transmission / reception unit 37 includes an opto-electric (O / E) conversion unit and an electro-optical (E / O) conversion unit, and performs optical communication with the parent device 40. The timer group 36 has various timers including a detector timer 38.

  The delay correction unit 31 includes an uplink interference determination unit 32 and a delay correction amount calculation unit 33. The uplink interference determination unit 32 activates the detector 38 at the start of the GP interval, determines whether there is an uplink interference signal from another system in the GP interval, and notifies the delay correction amount calculation unit 33 of the determination result. To do. The uplink interference determination unit 32 refers to the detector timer 38 when an uplink interference signal is detected in the GP section, and notifies the delay correction amount calculation unit 33 of the timer value at the time of interference signal detection.

  When there is no uplink interference signal in the GP section, the delay correction amount calculation unit 33 adds a predetermined delay correction amount A to the wired section. When there is an uplink interference signal in the GP section, the difference between the timer value of the detector timer 38 and the GP section length is calculated as the delay correction amount B, and the delay correction amount A + B is added to the wired section. The DAS base station apparatus 50 instructs the UE 20 with a timing advance value that takes into account the delay correction amount A or the delay correction amount A + B.

  In the distributed antenna device 60 of FIG. 12B, a DAS delay correction function for avoiding interference is provided in the parent device 40. The base unit 40 includes a delay correction unit 41 and an optical signal transmission / reception unit 47. The delay correction unit 41 includes an uplink interference determination unit 42 and a delay correction amount calculation unit 43.

  When receiving the uplink signal, the slave unit 30 notifies the master unit 40 of the detection result by the optical signal transmission / reception unit 37. The delay correction unit 41 of the parent device 40 performs the same operation as when the child device 30 includes the delay correction unit 31 based on the information or signal received from the child device 30.

  Alternatively, as shown in FIG. 12C, the distributed antenna device 70 may be configured by providing both the slave unit 30 and the master unit 40 with a DAS delay correction function for avoiding interference.

  12A to 12C, when there is an uplink interference signal from another system such as the macro base station 100 adjacent in the DAS 10, the desired signal from the UE 20 is received earlier than the interference signal. Uplink interference can be avoided by intentionally adding a delay correction amount and performing transmission control on the UE 20.

  13 to 15 are diagrams for describing the effect of improving the channel estimation accuracy by the delay correction according to the embodiment. As shown in FIG. 13A, slave unit 30 receives, for example, DMRS (Demodulation Reference Signal) transmitted on PUCCH (Physical Uplink Control Channel) as an uplink signal. To do. By reducing the DMRS interference, the channel estimation accuracy is improved.

As shown in FIG. 14, DMRS is arrange | positioned in the predetermined position of the time slot according to the format of PUCCH. In FIG. 13 (A), the the delay correction amount A or A + B is the first-out control that was added, DMRS within interference-free interval time t _d, earlier than the upstream interference signal from another system (e.g. macro base station 100) Received at.

FIG. 13B illustrates the number of DMRS symbols that are not subjected to uplink interference within the theoretical maximum no-interference interval time t _d [μs] for each special subframe (hereinafter, simply referred to as “SS”) configuration. (Per slot). Here, interference-free interval time _{t d} is set to 1/2 or less of the GP zone. When a normal cyclic prefix is used, nine types of SS configurations are defined as shown in FIG. 15 (the SS configuration when using an extended cyclic prefix is omitted).

  It can be seen that with SS configuration numbers 0 and 5, DMRS can be received without interference even in the presence of an uplink interference signal, which contributes to PUCCH channel estimation.

FIG. 16 shows an improvement effect of SINR (Signal to Interference-plus-Noise Ratio) by delay correction of the embodiment. As shown in FIG. 16 (A), if it does not receive an uplink interference signal from the macro base station 100 in the GP zone, by adding the delay correction amount A to the DAS delay correction, interference-free (low time t _d Interference) section is formed. When the average power of the interference signal is R [W] and the average power of the uplink desired signal is S [W], the SINR in one subframe (1 [ms]) is expressed by Equation (1).

このＳＩＮＲ値は、無干渉区間がない場合のＳＩＮＲと比較して、式（２）で表される分だけＳＩＮＲが改善されている。

This SINR value is improved by the amount expressed by the equation (2), compared with the SINR when there is no no-interference section.

図１６（Ｂ）は、ＳＳコンフィギュレーションごとに、無干渉区間時間ｔ_ｄの理論上の最大値とＳＩＮＲ改善値を示す。各ＳＳコンフィギュレーションで最大の無干渉区間時間ｔ_ｄを選定することで、ＳＩＮＲは０．１６［ｄＢ］〜１．９２［ｄＢ］改善される。

FIG. 16 (B) for each SS configuration, showing a maximum value and SINR improvement the theoretical interference-free section time _{t d.} By selecting the maximum interference-free section time _{t d} in the SS configuration, SINR is 0.16 [dB] ~1.92 [dB] improvement.

  FIG. 17 shows the improvement effect of the synchronization performance between the UE and the base station by the delay correction of the embodiment. In the TDD system, PRACH (Physical Random Access Channel) is transmitted in the UpPTS section. As shown in FIG. 17 (A), if the UpPTS section has no interference or low interference, the synchronization performance between the UT 20 and the DAS base station apparatus 50 is improved.

  FIG. 17 (B) is a diagram showing whether or not interference can be made in the UpPTS section for each SS configuration. A circle in the rightmost column of the table indicates that UpPTS can be made non-interacting, and a triangle indicates that UpPTS can be partially made non-interacting. With the SS configuration number 0.1.2.3.5.9, UpPTS can be made non-interfering. Even with other SS configuration numbers, the synchronization performance can be improved by partially decoupling UpPTS.

  FIG. 18 is a diagram illustrating the effect of delay correction according to the embodiment. For example, if the PUCCH format 1a in FIG. 14 and the SS configuration 0 in FIG. 15 are used, the delay correction amount A is 6600 Ts [μs], and the reception timing of the desired signal is 1000 Ts later than the interference signal, a total of 7600 Ts ( Delay correction of delay correction amount A + B) is added. Here, one subframe (1 ms) = 30720 Ts. In this case, one symbol of non-interfering PUCCH DMRS is included in the subframe, which can contribute to channel estimation.

In the example of FIG. 18, the maximum interference-free interval time _{t d} is 6600Ts, SINR is improved 1.05dB per subframe. Also, UpPTS becomes no interference, and PRACH is not affected by the interference signal.

  As described above, by using the time alignment control function of the DAS 10 to make the reception timing of the desired signal from the UE earlier than the reception timing of the interference signal, it is possible to prevent the influence of uplink interference.

10 Distributed antenna system (DAS)
20 UE (user terminal or mobile station)
30 Slave unit (distributed antenna device)
31 Delay Correction Unit 32 Uplink Interference Determination Unit 33 Delay Correction Amount Calculation Unit 36 Timer Group 38 Detector Timer 40 Master Unit 50 DAS Base Station Apparatus 60, 70 Distributed Antenna Apparatus

Claims (7)

A distributed antenna device used in a distributed antenna system,
A receiver for receiving an uplink desired signal from a mobile station;
Delay that adds a delay correction amount to the uplink desired signal from the mobile station so that the reception timing of the uplink desired signal at the base station of the distributed antenna system is earlier than the reception timing of the uplink interference signal A correction unit;
A distributed antenna device comprising: The delay correction unit includes:
An uplink interference determination unit that determines whether or not the uplink interference signal is detected in a guard period section of a special subframe for switching from a downlink subframe to an uplink subframe;
A delay correction amount calculator for adding a first delay correction amount to the uplink desired signal when the uplink interference signal is not detected in the guard period;
The distributed antenna device according to claim 1, comprising:   When the uplink interference signal is detected in the guard period interval, the delay correction unit calculates a second delay correction amount corresponding to a time from detection of the uplink desired signal to an end point of the guard period interval. 3. The distributed antenna device according to claim 2, wherein a calculation is performed and a total delay correction amount of the first delay correction amount and the second delay correction amount is added. A timer for measuring the detection time of the uplink interference signal;
Further comprising
The delay correction unit starts the timer at the start of the guard period interval, and when the uplink interference signal is detected in the guard period interval, the delay correction unit detects a time when the interference signal is detected from the start time of the guard period interval. 4. The distributed antenna device according to claim 3, wherein a difference between the recorded timer value and the time of the guard period interval is calculated as the second delay correction amount.   The first delay correction amount is a length at which a demodulation reference signal (DMRS) of at least one symbol per slot is received between the reception timing of the uplink desired signal and the reception timing of the uplink interference signal. The distributed antenna device according to claim 2, wherein   4. The dispersion according to claim 3, wherein the delay correction unit instructs the mobile station on an advance control amount to which the delay correction amount is added based on an instruction from a base station of the distributed antenna system. Antenna device. Receive the signal from the mobile station with the distributed antenna device of the distributed antenna system,
For the uplink desired signal from the mobile station, a delay correction amount for making the reception timing of the uplink desired signal in the base station of the distributed antenna system earlier than the reception timing of the uplink interference signal is the uplink interference. Give to the signal,
An interference control method characterized by the above.

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