KR20190047414A - Apparatus for interference rejection, and interference rejection mothod thereof - Google Patents

Abstract

The present invention relates to an interference cancellation apparatus and an interference cancellation method thereof capable of greatly increasing transmission efficiency and reliability of data transmission utilizing dynamic time-division-duplex communication since inter-cell interference occurring due to a difference between subcarrier intervals and interference simultaneously occurring from several cells may be efficiently removed even if subcarrier intervals are differently used in a fifth generation mobile communication environment supporting frequency division multiplexing and dynamic time-division-duplex communication technique.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an interference cancellation apparatus and an interference cancellation apparatus,

The present invention relates to an inter-cell interference caused by a difference in subcarrier spacing in a 5G mobile communication environment supporting frequency division multiplexing (FDM) and dynamic time division duplexing (D-TDD) And a method for removing the same.

In the current wireless communication system, an Orthogonal Frequency Division Multiple Access (OFDMA) technique is used, in which each user is allocated a specific band and transmits and receives data by dividing the allocated band into a plurality of subcarriers.

In OFDMA, the interval between subcarriers is maintained constant in all bands, and a band is allocated by adjusting the number of allocated subcarriers according to a user's request.

On the other hand, in the fifth generation mobile communication scenario, a method of allocating subcarrier intervals according to a channel environment is discussed.

This is because it is difficult to use the corresponding band at a frequency of 15 kHz, which is an interval between existing subcarriers, in a millimeter wave band of 60 GHz or more where a channel change is large, and also communication is performed in different channel environments for each user, Even if the same band is used, the degree or form of the interference experienced by each subcarrier varies depending on the channel environment.

In the fifth generation mobile communication environment, a number of devices are connected to generate various types of data traffic. Accordingly, uplink and downlink data rates may vary according to time depending on data traffic concentrated on the downlink .

In connection with this, dynamic time division duplexing technology is also discussed as one of the core technologies of the fifth generation mobile communication system.

As described above, the dynamic time division duplex communication technique is a technique in which time resources are dynamically changed according to the ratio of the uplink and downlink data, unlike the dual communication technique in which existing resources are fixed in an environment having various uplink and downlink data ratios .

However, when the dynamic time-division duplex communication technique is used, bands having different subcarrier spacing may exist in adjacent cells. In this case, another problem of inter-cell interference that has not existed .

Therefore, considering the fifth generation mobile communication environment supporting dynamic time division duplex communication based on frequency division multiplexing (FDM), new interference between cells can be eliminated due to a difference in subcarrier spacing There needs to be a plan.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a mobile communication system and a mobile communication method, in which interference between cells caused by a difference in subcarrier intervals in a 5G mobile communication environment supporting frequency division multiplexing technology and dynamic time- In order to effectively remove the defects.

According to another aspect of the present invention, there is provided an interference canceling apparatus including a comparator for comparing a subcarrier interval used in a service cell in which the interference canceller is located and a subcarrier interval used in a neighboring cell adjacent to the service cell, ; And an interference signal generated by the neighboring cell with respect to a service signal of the service cell by applying a result of comparing a subcarrier interval between the service cell and the neighboring cell to a service signal of the neighboring cell, And a removing unit for removing the interference signal from the reception signal received from the adjacent cell.

Specifically, the service signal of the neighboring cell is obtained from shared information shared through a back hole between the service cell and the neighboring cell, and the interference signal includes a difference between a subcarrier interval difference between the service cell and the neighboring cell And converting the service signal of the neighboring cell.

Specifically, the interference signal may be generated such that the number of subcarriers during a specific time period in which the service signal of the service cell has the same number of subcarriers as the service signal of the neighboring cell coincide with the subcarrier interval used by the service cell And may be determined by transforming the service signal of the neighboring cell.

Specifically, the interference signal is determined by dividing a service signal of the neighbor cell by the specific time period on a time axis when a subcarrier interval used in the service cell is longer than a subcarrier interval in the neighboring cell, When a subcarrier interval being used in the service cell is shorter than a subcarrier interval in the neighboring cell, a method of neighboring each service signal of two or more consecutive neighboring cells on a frequency axis for a specific time period, . ≪ / RTI >

Specifically, the interference signal may be a downlink service signal for the uplink service signal in the service cell or an uplink service signal for the downlink service signal in the service cell, Signal.

More specifically, if the number of the neighboring cells is two or more, the removing unit extracts, from each of the two or more neighboring cells, a subcarrier interval used in the service cell and a subcarrier interval used in each of the two or more adjacent cells, The interference signal of the two or more adjacent cells can be removed from the received signal received from the service cell and the two or more neighboring cells by determining the received interference signal.

According to an aspect of the present invention, there is provided a method of canceling interference in a service cell, the method comprising: comparing a sub-carrier interval used in the service cell with a sub-carrier interval used in a neighboring cell adjacent to the service cell; A determination step of determining an interference signal generated by the neighboring cell with respect to a service signal of the service cell by applying a result of comparing a subcarrier interval between the service cell and the neighboring cell to a service signal of the neighboring cell; And a removing step of removing the interference signal from the reception signal received from the service cell and the neighboring cell.

Specifically, the method may further include an acquiring step of acquiring a service signal of the neighboring cell from shared information shared through a back hole between the service cell and the neighboring cell before the determining step, The determining step may be determined by transforming a service signal of the neighboring cell based on a difference in subcarrier spacing between the serving cell and the neighboring cell.

Specifically, in the determining step, the number of sub-carriers during a specific time period in which a service signal of the service cell is included according to a sub-carrier interval being used in the service cell and the number of sub- The interference signal can be determined by converting the service signal of the neighboring cell.

More specifically, when the subcarrier interval being used in the service cell is longer than the subcarrier interval in the neighboring cell, the determining step comprises: dividing the service signal of the neighboring cell on the time axis by the specific time period, Wherein when the subcarrier interval being used in the service cell is shorter than the subcarrier interval in the neighboring cell, each of the service signals of two or more adjacent cells consecutive in the frequency axis during the specific time period is adjacent The interference signal can be determined in a manner that the interference signal is connected.

Specifically, the interference signal may be a downlink service signal for the uplink service signal in the service cell or an uplink service signal for the downlink service signal in the service cell, Signal.

Specifically, in the case where the number of the neighboring cells is two or more, the determining step may include determining, for each of the two or more neighboring cells, based on a result of comparing a subcarrier interval used in the service cell and a subcarrier interval used in each of the two or more adjacent cells, So that the interference signal of each of the two or more adjacent cells can be removed from the received signal received from the service cell and the two or more adjacent cells.

Thus, according to the interference cancellation apparatus and the interference cancellation method of the interference canceller of the present invention, even when the intervals between sub-carriers are differently used in the 5G mobile communication environment supporting frequency division multiplexing and dynamic time division duplex communication technology, It is possible to effectively remove the inter-cell interference caused by the difference or the simultaneous multi-cell interference, so that the transmission efficiency of the system utilizing the dynamic time division duplex communication and the reliability of the data transmission can be greatly improved.

1 is an exemplary diagram illustrating a mobile communication environment according to an embodiment of the present invention;
2 is an exemplary diagram for explaining interference due to subcarrier leakage according to an embodiment of the present invention;
3 is an exemplary diagram of a frequency axis for different subcarrier spacing according to an embodiment of the present invention;
4 is an illustration of a time axis for different subcarrier intervals in accordance with an embodiment of the present invention.
FIG. 5 is a diagram illustrating a case where a subcarrier interval between a serving cell and a neighboring cell is the same according to an embodiment of the present invention; FIG.
FIG. 6 is an exemplary diagram illustrating a case where a subcarrier interval of a service cell is longer than an adjacent cell interval according to an embodiment of the present invention; FIG.
FIG. 7 is an exemplary diagram illustrating a case where a subcarrier interval of a service cell is shorter than an interval of adjacent cells according to an embodiment of the present invention; FIG.
8 is a configuration diagram showing a schematic configuration of an interference elimination apparatus according to an embodiment of the present invention;
9 is a block diagram for explaining a method of determining an interference signal when a subcarrier interval of a service cell is longer than a neighboring cell interval according to an embodiment of the present invention.
10 is a block diagram generalizing a method of determining an interference signal when a subcarrier interval of a service cell is longer than an interval of adjacent cells according to an embodiment of the present invention.
11 is a block diagram for explaining a method of determining an interference signal when a subcarrier interval of a service cell is shorter than an interval of adjacent cells according to an embodiment of the present invention.
12 is a block diagram generalizing a method of determining an interference signal when a subcarrier interval of a service cell is shorter than an interval of adjacent cells according to an embodiment of the present invention.
FIG. 13 is an exemplary diagram for explaining a case where a plurality of adjacent cells are provided according to an embodiment of the present invention; FIG.
FIG. 14 is a block diagram for explaining a method of determining an interference signal when there are a plurality of neighboring cells according to an embodiment of the present invention; FIG.
15 is a flowchart for explaining an interference cancellation method of an interference canceller according to an embodiment of the present invention;

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

1 is an exemplary diagram illustrating a mobile communication environment according to an embodiment of the present invention.

1, the mobile communication environment according to an embodiment of the present invention may include a first service cell C1 and a first service cell C2 and a second service cell C2 adjacent to the first service cell C1, The first service cell C1 and the second service cell C2 are in a fifth generation mobile communication environment supporting dynamic time division duplex communication technology based on Frequency Division Multiplexing (FDM), respectively.

Accordingly, the first service cell C1 and the second service cell C2 according to an embodiment of the present invention use different subcarrier intervals according to a channel environment and use the uplink and downlink data The time resources are dynamically allocated according to the ratio.

Here, the subcarrier interval, which may vary depending on the channel environment, may be allocated to intervals of, for example, 7.5 kHz, 15 kHz, 30 kHz, 60 kHz, etc. set to an exponentiation of 2 of 15 kHz based on 15 kHz.

According to an embodiment of the present invention, the first service cell C1 and the second service cell C1 and the second service cell C1 are allocated according to a dynamic time-division duplex communication technique in which time resources are dynamically allocated according to the ratio of data of the uplink and the downlink, C2 use different links (uplink and downlink) at the same time resources, respectively.

That is, if the downlink is being used in the first service cell C1, it can be understood that the uplink is used in the first service cell C1 and the second service cell C2 adjacent to the first service cell C1.

However, when the first service cell C1 uses the downlink according to the dynamic time division duplex communication technique and the uplink is used in the adjacent second service cell C2, the first service cell C1, which transmits the downlink, (Base station-to-base station) to the base station of the second service cell (C2) receiving the uplink from the base station of the base station (C1).

In addition to this inter-base-station interference, inter-user interference from the terminal (user) transmitting the uplink in the second service cell C2 to the terminal (user) receiving the downlink from the first service cell C1, -to-user equipment may also be present.

Meanwhile, in the embodiment of the present invention, it has been mentioned that the subcarrier interval may be different according to the channel environment as well as the dynamic time division duplex communication technique described above.

In this connection, in an environment in which the first service cell C1 and the second service cell C2 use different links according to the dynamic time division duplex communication technique, the first service cell C1 and the second service cell C2 use different subcarrier intervals, the bandwidths between the base stations or the users (terminals) due to different subcarrier interval usage coexist between the first service cell C1 and the second service cell C2.

In the case where the bandwidths between the base stations or the users (terminals) due to the use of different sub-carrier intervals coexist between the first service cell C1 and the second service cell C2 as described above, of the cell to use the sub-carrier spacing (Δf _0), the user (terminal) or a long sub-carrier interval (2 x Δf ₀₎ of the user to use (UE) or a new type of interference of the interference by the leakage (leakage) of a base station from the base station Lt; / RTI >

For ease of explanation, FIG. 3 shows examples of different subcarrier spacing in the same band on the frequency axis.

3, the subcarrier interval of (A) is twice the subcarrier interval of (B), and the subcarrier interval of (C) is half the subcarrier interval of (B) It is shown as an example.

Here, the subcarrier interval of the p-th cell is denoted by fp.

In addition, FIG. 4 shows an example of different subcarrier intervals in FIG. 3 on the time axis.

In FIG. 4, a time period (symbol period) is 1/2 times that of the subcarrier interval of (B), and a subcarrier interval of 1 / It can be confirmed that the time period (symbol period) becomes twice as much as twice as much as (C).

Here, the orthogonal frequency division multiplexing (OFDM) symbol period of the p-th cell is represented by Tp.

Hereinafter, with reference to FIG. 5 through FIG. 7, a description will be made of a new type of interference that may occur due to the subcarrier spacing difference in an embodiment of the present invention.

FIG. 5 exemplarily shows that signals of two users or two base stations using different links are overlapped on a frequency axis and a time axis.

At this time, the subcarrier spacing of the two signals is the same. When the two signals having the same subcarrier spacing are overlapped, a new type of interference due to the leakage mentioned above does not occur.

On the other hand, FIG. 6 shows that the signals of two users or two base stations using different links having a difference of two subcarrier intervals are overlapped on the frequency axis and the time axis.

In FIG. 6 (A), it can be seen that the interference subcarrier spacing in the frequency axis is half the subcarrier spacing of the desired signal. In FIG. 6 (B), the period of the interference signal in the time axis corresponds to the desired signal period Which is twice as long.

In this way, the zero-crossing in the frequency axis does not occur in the interference signal when the interference sub-carrier interval is short, and there is no influence on the interference due to the leakage in the superposition signal itself.

However, since the interference signal is a long signal on the time axis, in order to recover the desired signal from the superimposed signal, it is necessary to recover only the T ₀ from the overlapped signal and restore it. Leakage occurs when orthogonality breaks.

That is, a new type of interference due to leakage occurs in the process of restoration.

FIG. 7 also shows that the signals of two users or two base stations using different links having a difference of 2 times the subcarrier interval are superimposed on the frequency axis and the time axis, as in FIG.

In FIG. 7 (A), it can be seen that the interference subcarrier spacing is twice the desired signal subcarrier spacing. In FIG. 7 (B), the signal period of the interference in the time axis is 1/2 It shows that it is a ship.

In this way, when the interval of the subcarrier interference is long, zero crossing occurs in the frequency axis, and the received signal is already influenced by the leakage interference.

However, since the interference signal is a short signal on the time axis, unlike the case where the interval of the subcarrier interference is short, the orthogonality of the interference signal is not broken when restoring the overlapped signal by cutting only T ₀ in the overlapped signal to recover the desired signal. Do not.

That is, it can be understood that there is a new type of interference due to leakage of the superposition signal itself, but there is no interference in the restoration process.

As described above, in the fifth generation mobile communication environment, when the inter-cell sub-carrier intervals are differently based on the dynamic time division duplex communication, a long sub-carrier interval (? F ₀ ) It can be seen that a new interference occurs due to leakage to a user (terminal) or a base station using (2 x? F ₀ ).

Therefore, in an embodiment of the present invention, a new scheme for eliminating inter-cell interference that may newly occur in the fifth generation mobile communication environment is proposed. Hereinafter, a structure of the interference canceller 100 will be described in detail .

Here, the interference canceller 100 transmits the downlink when the first service cell C1 uses the downlink according to the dynamic time division duplex communication technique and the uplink is used in the second service cell C2 The base station of the second service cell C2 that is affected by the interference from the base station of the first service cell C1 or the base station of the second service cell C2 that is influenced by the interference from the terminal It can be understood that it is the first service cell C1 terminal (user).

When the interference canceller 100 is a base station of the second service cell C2, the second service cell C2 is a service cell in which the interference canceller 100 is located, and the first service cell C1 is a service cell It can be understood that it is an adjacent cell adjacent to the cell.

Conversely, when the interference canceller 100 is the first service cell C1 terminal (user), the first service cell C1 is a service cell in which the interference canceller 100 is located, and the second service cell C2 ) Can be understood as a neighboring cell adjacent to a service cell.

Therefore, in the following description, for convenience of explanation, the service cell where the interference canceller 100 is located, and the service cell where the interference canceller 100 is located, without any reference to the first service cell C1 and the second service cell C2, Only the adjacent cells will be described.

FIG. 8 shows a schematic configuration of an interference canceller 100 according to an embodiment of the present invention.

As shown in FIG. 8, the interference canceller 100 according to an embodiment of the present invention may have a configuration including a comparison unit 10 and a removal unit 20.

The entire configuration or at least a part of the interference canceller 100 may be implemented in the form of a hardware module or a software module, or a combination of a hardware module and a software module.

Here, the software module can be understood as, for example, a command executed by a processor that processes an operation in the interference canceller 100, and the command can be stored in a separate memory in the interference canceller 100 Lt; / RTI >

Meanwhile, the interference canceller 100 according to an embodiment of the present invention may further include a communication unit 30, which is an RF module that performs a practical communication function with another device (base station or terminal) in a service cell, in addition to the above- And the like.

Here, the communication unit 30 includes, but is not limited to, an antenna system, an RF transceiver, one or more amplifiers, a tuner, one or more oscillators, a digital signal processor, a CODEC chipset, But may include all known circuits to perform.

As a result, the interference cancellation apparatus 100 according to an embodiment of the present invention can remove inter-cell interference that may newly occur in the fifth generation mobile communication environment through the above-described configuration. Hereinafter, an interference cancellation apparatus The configuration of the image forming apparatus 100 will be described in more detail.

The comparator 10 performs a function of comparing subcarrier intervals.

More specifically, when there is a neighboring cell causing inter-cell interference with respect to a service cell, the comparison unit 10 compares the sub-carrier interval used in the serving cell with the sub-carrier interval used in the neighboring cell.

Here, the information on the sub-carrier interval being used in the adjacent cell can be obtained from the shared information shared through the back-Hole between the service cell and the adjacent cell. The shared information includes not only the sub- , A service signal (service data) of a neighboring cell, a modulation technique, channel coding information, scheduling information, and the like.

Whether a neighboring cell causing inter-cell interference exists for a service cell can be confirmed from a result of transforming (FFT) a received signal received from a serving cell and a neighboring cell.

In the case where the adjacent cell causes inter-cell interference with the service cell, the reception signal has a form in which the service signal of the service cell and the service signal of the neighboring cell, which can be recognized by the interference signal for the service signal, are superimposed do.

The removing unit 20 performs a function of removing an interference signal.

More specifically, the removal unit 20 removes the interference signal from the received signal received from the serving cell and the adjacent cell, using the result of comparing the subcarrier interval between the serving cell and the adjacent cell.

At this time, the removal unit 20 compares the subcarrier interval difference between the service cell and the adjacent cell before the interference signal is removed, that is, the subcarrier interval difference between the service cell and the adjacent cell is applied to the service signal of the adjacent cell, And determines the interference signal generated by the adjacent cell with respect to the signal.

Here, the service signal of the neighboring cell can be obtained from the sharing information shared through the back-Hole between the service cell and the neighboring cell as described above.

As described above, the determination of the interference signal, which is determined using the subcarrier spacing difference between the serving cell and the adjacent cell, follows the following scheme.

As a result of comparing the subcarrier interval between the serving cell and the neighboring cell, as described above with reference to FIG. 5, the subcarrier interval? F ₀ between the serving cell and the adjacent cell is equal to each other.

In this case, the service signal of the service cell and the service signal of the adjacent cell have the same subcarrier interval. When these two signals are overlapped, a new type of interference due to the leakage mentioned above does not occur.

Accordingly, when the service signal of the service cell and the service signal of the neighboring cell have the same subcarrier interval, the removal unit 20 deletes the service signal of the adjacent cell obtained from the shared information, Can be determined as a signal.

Next, results of comparing the sub-carrier interval between the serving cell and neighboring cells, as described with reference to Figure 6 above, two times compared to the sub-carrier spacing (Δf _0/2) of the sub-carrier spacing (Δf ₀₎ of the serving cell neighbor cell For example.

In this case, a service signal of a neighboring cell with a short subcarrier interval does not have zero crossing with a service signal of a service cell on the frequency axis, and the overlap signal itself does not affect interference due to leakage.

However, since the service signal of the adjacent cell is longer than the service signal of the service cell on the time axis, it is necessary to recover only the T ₀ from the superimposed signal in order to recover the desired signal from the overlapped received signal, The signal is leaked due to the distortion of the orthogonality of the interference signal.

Thus, the removal unit 20 thus sub-carrier interval of the serving cell (Δf ₀₎ through the sub-carrier spacing (Δf _0/2) if 2 times compared to, the way of dividing the service signals of the neighboring cells in the time-axis of the neighboring cell The interference signal is determined, and further, only the service signal of the service cell can be recovered from the received signal by removing the determined interference signal from the received signal.

This determination of the interference signal and the removal operation of the interference signal can be specifically described with reference to FIG.

Referring to FIG. 9, an N-sized FFT, which is a fast Fourier transform (FFT) size of a service signal of a service cell, is performed on a received signal in which a service signal of a service cell and an interference signal are overlapped.

Here, the N size can be understood as the number of sub-carriers included in the service signal of the service cell according to the sub-carrier interval used in the service cell.

Then, the IFFT of 2N size is performed for the service signal of the neighboring cell obtained through the shared information, (b) the result of performing N-sized FFT on the N-sized data and the N-sized data after It is determined as an interference signal included in the received signal.

Finally, if the interference signal thus determined is subtracted from the FFT-processed received signal, the service signal of the service cell from which the interference signal has been removed from the received signal can be recovered (d).

For reference, FIG. 10 shows a form in which the interference signal determination method described with reference to FIG. 9 is generalized and blocked.

As, when the FFT size of the service signal of the serving cell N, as the subcarrier spacing f ₀ La, and the FFT size KN, Kf the sub-carrier interval ₀ of the service signal of the adjacent cell as adjacent cell shown in Figure 10 The IFFT of the KN-sized service signal is divided into the N-sized signals, and the N-sized FFT processing is performed on each signal. Thereafter, the signals are selected in accordance with the time order to be determined as the interference signals.

Further, the result of comparing the sub-carrier interval between adjacent cells and the serving cell, as described with earlier with reference to Figure 7, the subcarrier spacing of the adjacent cells (2 x Δf ₀₎ is 2 times compared with the sub-carrier interval of the serving cell (Δf ₀₎ For example.

In this case, since the service signal of the adjacent cell is shorter than the service signal of the service cell on the time axis, the orthogonality of the neighboring cell service signal is broken when the overlapped signal is only truncated by T ₀ .

Thus, the removal unit 20 subcarrier spacing of the adjacent cell thus (2 x Δf _0), the axis of two times the case, each service signals of the neighboring cells that are continuous in the frequency axis compared to the sub-carrier interval of the serving cell (Δf ₀₎ time The interference signal is determined through a method of neighboring connections in the neighboring cell, and further, only the service signal of the service cell can be recovered from the received signal by removing the determined interference signal from the received signal.

This determination of the interference signal and the removal operation of the interference signal can be specifically described with reference to FIG.

Referring to FIG. 11, an N-sized FFT, which is a FFT (fast Fourier transform) size of a service signal of a service cell, is performed on a received signal in which a service signal of a service cell and an interference signal are superimposed.

Here, the N size can be understood as the number of sub-carriers included in the service signal of the service cell according to the sub-carrier interval used in the service cell.

Then, an N-sized IFFT is performed for the N / 2 service signals and the N / 2 service signals after the service signal of the N-sized neighboring cell obtained through the shared information (b) (C) The service signal of N size can be obtained by cascading N / 2 two FFT processed service signals. (D) The interference signal can be determined by FFT processing of the service signal of N size.

Finally, if the interference signal thus determined is subtracted from the FFT-performed received signal, the service signal of the service cell from which the interference signal has been removed from the received signal can be recovered (e).

For reference, FIG. 12 exemplarily shows a form in which the interference signal determination method described with reference to FIG. 11 is generalized and blocked.

Cost, the FFT size for the service signals in the serving cell N, referred to the sub-carrier spacing f _0, and the FFT size of the adjacent cell causes interference N / K, the subcarrier intervals as shown in Figure 11. Speaking of f ₀ / K , An interference signal can be determined by dividing an adjacent cell service signal into N / K sizes, passing through N / K size IFFTs, connecting the signals to a total N size signal, and passing through an FFT.

Meanwhile, in one embodiment of the present invention, a case where one neighboring cell causes interference to a service cell has been described. However, it is also possible to consider a case where a plurality of neighboring cells generate interference with respect to a service cell, which is not limited thereto.

FIG. 13 shows a signal in which inter-subcarrier interference is superimposed when a plurality of adjacent cells generate interference with respect to a service cell.

At this time, the total number of cells is P + 1, and one of them can be understood as a cell for the user or the base station, that is, the interference canceller 100, receiving the signal.

Here, the subcarrier spacing of each cell is denoted by fp (p = 0, 1, ..., P) and the period of each cell is denoted by Tp (p = 0, 1, ..., P).

In this regard, FIG. 14 shows a method of eliminating interference in an environment in which interference occurs from P adjacent cells, as shown in FIG.

That is, a subcarrier interval for each neighboring cell that causes interference to a service cell and a service signal in each neighboring cell can be acquired. Using the form of the interference signal determination method described above with reference to FIGS. 10 and 12, It is possible to recover only the service signal of the service cell from the received signal by determining the interference signal for each neighboring cell, summing all the determined interference signals, and subtracting the summed result from the received signal that has passed through the N-sized FFT .

As described above, according to the interference canceller 100 according to an embodiment of the present invention, the number of sub-carriers during a specific time period in which a service signal of a service cell is provided according to a sub- The interference signal is determined through a method of transforming a service signal of a neighboring cell so that the number of subcarriers included in the service signal of the cell coincides with each other and the interfering signal is removed from the received signal received from the service cell and the adjacent cell It can be seen that the service signal in the service cell can be effectively restored. In addition, according to the interference cancellation apparatus 100 according to an embodiment of the present invention, it is possible to effectively remove interference generated simultaneously from a plurality of adjacent cells through the above-described scheme, so that a system utilizing dynamic time- The transmission efficiency and the reliability of data transmission can be greatly improved.

Hereinafter, an interference cancellation method in the interference canceller 100 according to an embodiment of the present invention will be described with reference to FIG.

First, the comparison unit 10 checks whether there is a neighboring cell that causes inter-cell interference with respect to a service cell, and if there is a neighboring cell that is interfering with the service cell, the comparison unit 10 uses the sub- Carrier intervals (S11-S13).

Here, the information on the sub-carrier interval being used in the adjacent cell can be obtained from the shared information shared through the back-Hole between the service cell and the adjacent cell. The shared information includes not only the sub- , A service signal (service data) of a neighboring cell, a modulation technique, channel coding information, scheduling information, and the like.

Whether a neighboring cell causing inter-cell interference exists for a service cell can be confirmed from a result of transforming (FFT) a received signal received from a serving cell and a neighboring cell.

In the case where the adjacent cell causes inter-cell interference with the service cell, the reception signal has a form in which the service signal of the service cell and the service signal of the neighboring cell, which can be recognized by the interference signal for the service signal, are superimposed do.

Then, the removal unit 20 compares the subcarrier interval difference between the service cell and the adjacent cell before the removal of the interference signal, that is, the subcarrier interval difference between the service cell and the adjacent cell is applied to the service signal of the adjacent cell, And determines an interference signal generated by the adjacent cell with respect to the service signal.

Here, the service signal of the neighboring cell can be obtained from the sharing information shared through the back-Hole between the service cell and the neighboring cell as described above.

At this time, the removal unit 20 compares the subcarrier interval difference between the service cell and the adjacent cell before the interference signal is removed, that is, the subcarrier interval difference between the service cell and the adjacent cell is applied to the service signal of the adjacent cell, The interference signal generated by the adjacent cell with respect to the signal can be determined.

That is, as a result of comparing the subcarrier interval between the serving cell and the adjacent cell, as described above with reference to FIG. 5, when the subcarrier interval? F ₀ between the serving cell and the adjacent cell are equal to each other, The service signals of the first and second antennas have the same subcarrier interval. When these two signals are overlapped, a new type of interference due to the leakage mentioned above does not occur.

Accordingly, when the service signal of the service cell and the service signal of the neighboring cell have the same subcarrier interval, the removal unit 20 deletes the service signal of the adjacent cell obtained from the shared information, (S14-S15).

Further, the result of comparing the sub-carrier interval between the serving cell and neighboring cells, as described with reference to Figure 6 above, two times compared to the sub-carrier spacing (Δf _0/2) of the sub-carrier spacing (Δf ₀₎ of the serving cell neighbor cell In this case, the service signal of the adjacent cell with a short subcarrier interval does not have zero crossing with the service signal of the service cell on the frequency axis, and the overlap signal itself does not affect the interference caused by the leakage.

However, since the service signal of the adjacent cell is longer than the service signal of the service cell on the time axis, it is necessary to recover only the T ₀ from the superimposed signal in order to recover the desired signal from the overlapped received signal, The signal is leaked due to the distortion of the orthogonality of the interference signal.

At this time, the removal unit 20 thus sub-carrier interval of the serving cell (Δf ₀₎ through the sub-carrier spacing (Δf _0/2) if 2 times compared to, the way of dividing the service signals of the neighboring cells in the time-axis of the neighboring cell The interference signal can be determined (S16-S17).

9, an N-sized FFT (fast Fourier transform) size of a service signal of a service cell is performed on a received signal in which a service signal of a service cell and an interference signal are overlapped, Then, the IFFT of 2N size is performed for the service signal of the adjacent cell obtained through the shared information, (b) the result of performing the N-sized FFT on the N-sized data and the N- As an interference signal included in the received signal.

On the other hand, as a result of comparing the sub-carrier interval between adjacent cells and the serving cell, as described with earlier with reference to Figure 7, the subcarrier spacing of the adjacent cells (2 x Δf ₀₎ is 2 times compared with the sub-carrier interval of the serving cell (Δf ₀₎ The orthogonality of the adjacent cell service signal is broken when the service signal of the neighbor cell is cut off by T ₀ only in the overlapped signal because the service signal of the neighbor cell is shorter than the service signal of the service cell on the time axis.

Thus, the removal unit 20 subcarrier spacing of the adjacent cell thus (2 x Δf _0), the axis of two times the case, each service signals of the neighboring cells that are continuous in the frequency axis compared to the sub-carrier interval of the serving cell (Δf ₀₎ time (S18). In this case, the interference signal is determined through a method of neighboring neighboring cells in the neighboring cell. Then, only the service signal of the service cell can be recovered from the received signal by removing the determined interference signal from the received signal.

That is, referring to FIG. 11, (a) an N-sized FFT is performed on a received signal in which a service signal of a service cell and an interference signal are superimposed on each other and a fast Fourier transform (FFT) (B) Next, an N-sized IFFT is performed for the N / 2 service signals and the N / 2 service signals after the service signal of the N-sized neighboring cell obtained through the shared information, (C) The service signal of N size can be obtained by cascading two N / 2 FFT processed service signals obtained. (C) The interference signal can be determined by FFT processing the service signal of N size.

Thereafter, the removal unit 20 applies a result of the subcarrier interval comparison between the service cell and the neighboring cell to the service signal of the neighboring cell, and determines an interference signal generated by the neighboring cell with respect to the service signal of the service cell The service signal of the service cell is restored in a manner of removing the interference signal determined from the reception signal received from the service cell and the neighboring cell (S19-S20).

As described above, according to the interference cancellation method in the interference cancellation apparatus 100 according to an embodiment of the present invention, when a service signal of a service cell is received according to a subcarrier interval used in a service cell, The interference signal is determined through a method of transforming a service signal of a neighboring cell so that the number of subcarriers and the number of subcarriers included in a service signal of a neighboring cell coincide with each other. It can be seen that the service signal in the service cell can be effectively restored through the method of removing the interference signal. In addition, according to the interference canceller 100 according to an embodiment of the present invention, it is possible to effectively remove interference generated simultaneously from a plurality of adjacent cells through the above scheme, The transmission efficiency and the reliability of data transmission can be greatly improved.

Meanwhile, the interference cancellation method according to an embodiment of the present invention may be implemented in the form of a program command that can be performed through various computer means and recorded in a computer readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

According to the interference cancellation apparatus and the interference cancellation method in the interference cancellation apparatus according to the present invention, a mobile communication supporting a frequency division multiplexing (FDM) technique and a dynamic time division duplexing (D-TDD) Since it is possible to effectively eliminate the interference generated between cells due to the difference in the subcarrier interval in the environment, as the conventional technology is overcome, it is not possible to use only the related technology, In addition, it is an invention that can be used industrially because it is practically possible to carry out clearly.

100: interference canceller
10:
20: Removal

Claims (12)

In the interference canceller,
A comparison unit comparing a sub-carrier interval used in a service cell in which the interference canceller is located and a sub-carrier interval used in a neighboring cell adjacent to the service cell; And
Wherein the interference signal generated by the neighboring cell is determined for a service signal of the service cell by applying a result of comparing a subcarrier interval between the service cell and the neighboring cell to a service signal of the neighboring cell, And an elimination unit for removing the interference signal from the reception signal received from the adjacent cell. The method according to claim 1,
Wherein the service signal of the neighboring cell includes:
The service information is obtained from shared information shared between the service cell and the neighboring cell through a back hole,
The interfering signal may comprise:
Wherein a service signal of the neighboring cell is transformed based on a difference in subcarrier spacing between the serving cell and the neighboring cell. 3. The method of claim 2,
The interfering signal may comprise:
A service signal of the neighbor cell is transformed so that the number of subcarriers of the service cell of the neighbor cell is equal to the number of subcarriers of the service cell of the neighbor cell, And the interference canceller is determined by the interference canceller. 3. The method of claim 2,
The interfering signal may comprise:
When a subcarrier interval being used in the service cell is longer than a subcarrier interval in the neighboring cell, a service signal of the neighboring cell is determined to be divided in each time period on the time axis,
When a subcarrier interval being used in the service cell is shorter than a subcarrier interval in the neighboring cell, a method of neighboring each service signal of two or more consecutive neighboring cells on a frequency axis for a specific time period, The interference canceller comprising: The method according to claim 1,
The interfering signal may comprise:
A downlink service signal in the neighboring cell for the uplink service signal in the service cell or an uplink service signal in the neighboring cell for the downlink service signal in the service cell. Device. The method according to claim 1,
The removing unit
Determining an interference signal received from each of the two or more neighboring cells based on a result of comparing a subcarrier interval being used by the service cell and a subcarrier interval being used by each of the two or more neighboring cells, And removes the interference signal of each of the at least two adjacent cells from the reception signal received from the service cell and the at least two neighboring cells. A method for interference cancellation in a service cell,
Comparing a sub-carrier interval used in the service cell with a sub-carrier interval used in a neighboring cell adjacent to the service cell;
A determination step of determining an interference signal generated by the neighboring cell with respect to a service signal of the service cell by applying a result of comparing a subcarrier interval between the service cell and the neighboring cell to a service signal of the neighboring cell; And
And removing the interference signal from a received signal received from the service cell and the neighboring cell. 8. The method of claim 7,
The method comprises:
Further comprising an obtaining step of obtaining a service signal of the neighboring cell from share information shared through a back hole between the service cell and the neighboring cell before the determining step,
Wherein,
Wherein a service signal of the neighboring cell is transformed based on a difference in subcarrier spacing between the serving cell and the neighboring cell. 9. The method of claim 8,
Wherein,
A service signal of the neighbor cell is transformed so that the number of subcarriers of the service cell of the neighbor cell is equal to the number of subcarriers of the service cell of the neighbor cell, And the interference signal is determined. 9. The method of claim 8,
Wherein,
Determining an interference signal by dividing a service signal of the neighboring cell on the time axis every predetermined time period when a subcarrier interval being used in the service cell is longer than a subcarrier interval in the neighboring cell,
When a subcarrier interval being used in the service cell is shorter than a subcarrier interval in the neighboring cell, a method of neighboring each service signal of two or more consecutive neighboring cells on a frequency axis for a specific time period, And the interference signal is determined as the interference signal. The method according to claim 6,
The interfering signal may comprise:
A downlink service signal in the neighboring cell for the uplink service signal in the service cell or an uplink service signal in the neighboring cell for the downlink service signal in the service cell. Way. The method according to claim 6,
Wherein,
Determining an interference signal received from each of the two or more neighboring cells based on a result of comparing a subcarrier interval being used by the service cell and a subcarrier interval being used by each of the two or more neighboring cells, And the interference signal of each of the at least two adjacent cells is removed from a received signal received from the service cell and the at least two neighboring cells.

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