KR20110041283A - Apparus and method for receiving signal in wireless communication system and system thereof - Google Patents

Abstract

PURPOSE: A device and method for receiving a signal in a wireless communication system and a system thereof are provided to maximize frequency use efficiency by removing the influence of interference between base stations. CONSTITUTION: A QPSK modulator(101) QPSK-modulates a signal transmitted from a terminal. An S/P converter(103) converts modulated signal into a parallel signal. An IFFT unit(105) converts the parallel signal into a plurality of OFDM symbols by converting a frequency domain into a time domain. A CP inserter(109) inserts CP into the converted OFDM symbols for controlling the influence of a multiple path fading. A D/A converter(111) converts the OFDM symbols with the CP into an analog signal. The converted analog signal is transmitted to a receiving device through a preprocessor(113) like an antenna.

Description

Apparatus and method for receiving signal in wireless communication system and system therefor {APPARUS AND METHOD FOR RECEIVING SIGNAL IN WIRELESS COMMUNICATION SYSTEM AND SYSTEM THEREOF}

The present invention relates to an apparatus and method for receiving a signal in a wireless communication system, and more particularly, to an apparatus and method for receiving a signal in a wireless communication system based on time frequency division multiplexing (TDD) and a wireless communication system for the same. It is about.

 Most next-generation wireless communication systems adopt Orthogonal Frequency Division Multiplexing (OFDM) as a wireless transmission standard in order to maximize the data rate, and research on the TDD method has been actively conducted as a multiplexing method.

In using a wireless communication system employing the TDD scheme, at least two base stations each having a unique TDD symbol ratio (a symbol ratio of down-link and up-link) are the same. Coexistence in the region may occur. In this case, when each of at least two base stations receives a signal in the wireless communication system, an error may occur when the corresponding base station transmits / receives a signal due to interference due to a signal transmitted / received from another base station.

Therefore, when at least two base stations each having a unique TDD symbol ratio coexist in the same region, a method for solving the interference problem between base stations to efficiently receive a signal is required. do.

The present invention provides a receiving apparatus and method for blocking interference due to a signal transmitted by another base station overlapping a service area in a base station of a wireless communication system based on TDD, and a wireless communication system for supporting the same.

The present invention also provides a base station and method for receiving a signal from which interference is removed when at least two base stations each using a unique TDD symbol rate coexist in the same area, and a wireless communication system for the same. do.

The present invention also provides a receiver and method for removing interference that may be included in a received signal based on a difference in TDD symbol ratios between a plurality of base stations in a TDD-based wireless communication system, and a wireless communication system for supporting the same. .

The present invention also provides a receiving apparatus and method that does not receive a signal in a section where interference may occur due to a difference in TDD symbol ratios between a plurality of base stations in a TDD-based wireless communication system, and a wireless communication system for supporting the same. .

In a wireless communication system based on time frequency division multiplexing (TDD) according to an embodiment of the present invention, any one of at least two base stations each having a unique TDD symbol ratio may be a period during up-link time. Includes a receiver for receiving a signal in a time interval except for a time interval in which interference occurs due to a difference in a TDD symbol ratio, wherein the difference in the TDD symbol ratio is a TDD symbol of a base station including the receiver; It is characterized in that the difference between the ratio and the TDD symbol ratio of the remaining base station other than the base station including the receiving device of the at least two base stations.

In addition, in a wireless communication system based on time frequency division multiplexing (TDD) according to an embodiment of the present invention, a method in which at least one base station among at least two base stations each having a unique TDD symbol ratio receives a signal The method may include receiving a signal in a time interval except for a time interval in which an interference occurs due to a difference in a TDD symbol ratio in an up-link time interval, wherein the difference in the TDD symbol ratio is any one of the base stations. This is characterized in that the difference between the TDD symbol ratio and the TDD symbol ratio of the remaining base station other than the one of the at least two base stations.

In addition, a wireless communication system based on time frequency division multiplexing (TDD) according to an embodiment of the present invention includes a counterpart base station having an arbitrary TDD symbol ratio, the random base station having a random TDD symbol ratio and the counterpart base station; A source base station having a different TDD symbol ratio and receiving a signal in a time interval except for a time interval where interference occurs due to a difference in the TDD symbol ratio in an uplink time interval defined by the different TDD symbol ratio. Here, the difference in the TDD symbol ratio is characterized in that the difference between the arbitrary TDD symbol ratio and the different TDD symbol ratio.

According to the present invention, when at least two base stations each using a unique TDD symbol rate coexist in the same area, the base station may remove the influence of the interference regardless of the strength of the interference between the at least one other base station. Can be.

In addition, the present invention can remove the effect of interference regardless of the strength of interference between at least one other base station in the base station even if the same operator applies the TDD symbol ratio different for each region in the same frequency interval.

In addition, the present invention does not require a guard band for solving the interference problem, it is possible to maximize the frequency utilization efficiency.

On the other hand various other effects will be disclosed directly or implicitly in the detailed description of the embodiments of the present invention to be described later.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts will be omitted so as not to distract from the gist of the present invention.

An important aspect of the present invention is to provide a time interval in which any one of at least two base stations each having a unique TDD symbol rate in a wireless communication system causes interference due to a difference in TDD symbol rate in the up-link time interval. An apparatus and method for receiving a signal in the remaining time interval except for this and to provide a wireless communication system for the same. For example, in Korea, the TDD symbol ratio of 27:15 is applied, but since the technical standard is being changed to allow a plurality of TDD symbol ratios of 29:18, in this case, interference occurs due to the difference in the TDD symbol ratio. The present invention provides an apparatus and method for solving the problem and a wireless communication system for the same.

To this end, an embodiment of the present invention will be described in detail with respect to the apparatus and method for efficiently receiving a signal transmitted from the transmission apparatus of the base station and a wireless communication system for the same.

1 shows an apparatus for transmitting a base station in a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 1, a transmitter of a base station includes a quadrature phase shift keying (QPSK) modulator 101, a serial to parallel (S / P) converter 103, and an inverse fast Fourier transform (IFFT). Inverse Fast Fourier Transform (105), Parallel to Serial (P / S) Converter (107), Cyclic Prefix (CP) (109), Digital / Analog (D / A: Digital / Analog) converter 111 and preprocessor 113.

The QPSK modulator 101 performs QPSK modulation on a signal transmitted from the terminal, and the S / P converter 103 converts the modulated signal into a parallel signal. The IFFT unit 105 converts the converted parallel signal into a plurality of OFDM symbols by converting from the frequency domain to the time domain. The CP inserter 109 inserts a CP into each of the transformed OFDM symbols to control or reduce the effects of multipath fading, and the D / A converter 111 analogizes the OFDM symbols into which the CP is inserted. Convert to a signal. As a result, the converted analog signal is transmitted to the receiving device of FIG. 2 through a preprocessor 113 such as an antenna.

2 illustrates a receiving apparatus of a base station in a wireless communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the receiving apparatus includes a preprocessor 201, an analog / digital (A / D) converter 203, an interference canceller 205, an S / P converter 207, and a fast Fourier transform (FFT). A transformer 209, a channel estimator 211, an equalizer 213, a P / S converter 215, and a demodulator 217.

The preprocessor 201 receives a signal transmitted from a transmitting device through an antenna, and the A / D converter 203 converts the received signal into a digital signal.

The interference canceller 205 confirms whether interference due to a difference in TDD symbol ratio has occurred in the converted digital signal, and transmits the converted signal to the S / P converter 307 when interference due to a difference in TDD symbol ratio occurs. I never do that. 3 illustrates an example in which a difference in TDD symbol ratio occurs in base stations having different TDD symbol ratios.

Referring to FIG. 3, the first base station 310 has 102.857 usec per symbol, the downlink time interval is composed of 29 symbols, and the uplink time interval is composed of 18 symbols. The second base station 330 has 115.5 usec per symbol, the downlink time interval is composed of 27 symbols, and the uplink time interval is composed of 18 symbols. Accordingly, as shown in FIG. 3, the uplink time interval of the first base station 310 is generated 21.83 usec (about 1/5 symbols) earlier than the uplink time interval of the second base station 330. This causes a difference in the TDD symbol ratio of 21.83 usec (about 1/5 symbols) between the first base station 310 and the second base station 330.

Accordingly, the interference canceller 205 removes a signal generated during the 21.83 usec (about 1/5 symbol) in the uplink time interval of the first base station 310. That is, when the interference due to the symbol ratio difference occurs, the interference canceller 205 may remove all the signals received during the period affecting the interference so that the interference is not affected in any case regardless of the interference strength. However, in this case, since the signal to be originally received is also removed during the period affecting the interference, degradation of the up-link signal may occur, but the effect on the performance is very small when the period affecting the interference is not large.

In fact, when the base stations using the TDD symbol ratios of 29:18 and 27:15 coexist, the interval affected by the interference is about 1/5 symbols, as shown in FIG. 3, and according to an embodiment of the present invention When (205) is applied, performance degradation due to interference does not occur, and performance degradation due to degradation of the original signal is attenuated up to 0.4 dB or less of the SNR of the uplink control channel, and the effect on performance is very slight. . That is, when applying the interference canceller 205 according to the embodiment of the present invention, the receiving device can maintain the same performance regardless of the interference strength and can be applied regardless of the position of the interference source.

The S / P converter 307 converts the signal transmitted from the interference canceller 205 into a parallel signal, and the FFT unit 309 performs Fourier transform of the converted parallel signal from the time domain to the frequency domain.

The channel estimator 311 estimates channel characteristics based on the Fourier transformed signal, and the equalizer 313 calculates distortion of the Fourier transformed signal based on the channel characteristic estimation value output from the channel estimator 311. To compensate.

The P / S converter 315 converts the signal transmitted from the equalizer 313 into a serial signal, and the demodulator 317 demodulates the converted serial signal.

4 illustrates a signal reception method of a base station in a wireless communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 4, in step 401, the preprocessor 301 receives a signal transmitted from a transmitting device through an antenna, and in step 403, the A / D converter 303 converts the received signal into a digital signal.

In step 405, the interference canceller 205 checks whether the interference due to the TDD symbol rate difference occurs in the converted digital signal, and returns to step 401 when the interference due to the TDD symbol rate difference occurs. That is, in step 405, the interference canceller 205 removes all signals received during the period affecting the interference when the interference due to the symbol ratio difference occurs so that the interference is not affected in any case regardless of the interference strength. Can be.

On the other hand, in step 405, the interference canceller 205 proceeds to step 407 when no interference occurs due to the TDD symbol ratio difference. In step 407, the S / P converter 307 converts the transmitted signal into a parallel signal, and in step 409, the FFT unit 309 performs a Fourier transform of the converted parallel signal from the time domain to the frequency domain.

In operation 411, the channel estimator 311 estimates channel characteristics based on the Fourier transformed signal, and in operation 413, the equalizer 313 distorts the Fourier transformed signal based on the estimated channel characteristic estimation value. To compensate. In step 415, the P / S converter 315 converts the distortion compensated signal into a serial signal, and in step 417, the demodulator 317 demodulates the converted serial signal.

Accordingly, when wireless communication systems each using a unique TDD symbol ratio coexist in the same region, the receiving apparatus of the base station does not receive all signals received during a period affecting interference according to an embodiment of the present invention. Therefore, the signal transmitted from the transmitting device can be efficiently received.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the appended claims, but also by the equivalents of the claims.

For example, an embodiment of the present invention has been described as removing interference caused by a difference in TDD symbol ratio from a received signal to remove interference. As another example, however, interference may be removed by blocking transmission of a signal in a section in which interference may occur due to a difference in TDD symbol ratio for interference cancellation.

1 is a diagram illustrating an apparatus for transmitting a base station in a wireless communication system according to an embodiment of the present invention;

2 is a diagram illustrating a receiving device of a base station in a wireless communication system according to an embodiment of the present invention;

3 illustrates an example of base stations having different TDD symbol ratios;

4 is a diagram illustrating a received signal processing method in a receiving apparatus of a wireless communication system according to an exemplary embodiment of the present invention.

Claims (21)

In any one of at least two base stations each having a unique TDD symbol ratio in a wireless communication system based on Time Frequency Division Multiplexing (TDD), It includes a receiving device for receiving a signal in the remaining time interval except the time interval when interference occurs due to the difference in the TDD symbol ratio in the up-link period, Wherein the difference in the TDD symbol ratio is a difference between a TDD symbol ratio of the base station including the receiver and a TDD symbol ratio of the other base stations other than the base station including the receiver among the at least two base stations. The method of claim 1, wherein the receiving device, And an interference canceller for removing a signal received in a time interval where interference occurs due to a difference in the TDD symbol ratio from the signal received in the up-link period. The method of claim 1, wherein the receiving device, And an interference canceller configured to output a signal received in a remaining time interval except for a time interval in which interference occurs due to a difference in the TDD symbol ratio in the up-link time interval. The method according to any one of claims 2 to 3, The base station, characterized in that the service area by the at least two base stations overlap. The method according to any one of claims 2 to 3, The TDD symbol ratio is a base station characterized in that the ratio of the downlink interval and the uplink interval. The method of claim 5, The downlink time interval and uplink time interval ratio of the base station including the receiver is 27:15, and the downlink time interval and uplink time of the at least two base stations other remaining base stations other than the base station including the receiver are included. The base station, characterized in that the ratio of the link period is 29:18. The method of claim 5, The ratio of the downlink period and the uplink period of the base station including the receiving apparatus is 29:18, and the downlink period and the uplink interval of the at least two base stations belonging to the remaining base stations other than the base station including the receiving apparatus. The base station, characterized in that the link ratio is 27:15. In a wireless communication system based on time frequency division multiplexing (TDD), at least one of two base stations each having a unique TDD symbol ratio receives a signal. Receiving a signal in the time interval other than the time interval when the interference occurs due to the difference in the TDD symbol ratio in the up-link period, Wherein the difference between the TDD symbol ratios is a difference between the TDD symbol ratios of the at least one base station and the TDD symbol ratios of the remaining base stations other than the at least one base station among the at least two base stations. The method of claim 8, wherein the receiving process And removing the signal received in the time interval where interference occurs due to the difference in the TDD symbol ratio from the signal received in the up-link period. The method of claim 8, wherein the receiving process And outputting a signal received in a remaining time interval except for a time interval in which interference occurs due to a difference in the TDD symbol ratio in the up-link time interval. The method according to any one of claims 9 to 10, And a service area overlapped by the at least two base stations. The method according to any one of claims 9 to 10, The TDD symbol ratio is a ratio of a section during downlink and a section during uplink. The method of claim 12, The ratio of the downlink interval and the uplink interval of the one base station is 27:15, and the downlink interval and the uplink interval of the at least two base stations of the other base stations other than the one of the base stations Signal receiving method characterized in that the ratio is 29:18. The method of claim 12, The ratio of the downlink interval and the uplink interval of the one base station is 29:18, and the downlink interval and the uplink interval of the at least two base stations of the other base stations other than the one of the base stations Signal receiving method characterized in that the ratio is 27:15. In the wireless communication system based on Time Frequency Division Multiplexing (TDD), A counterpart base station having an arbitrary TDD symbol rate, The other base station has a TDD symbol rate that is different from the random TDD symbol rate that the counterpart base station has, except for a time period when interference occurs due to a difference in the TDD symbol rate in the uplink time interval defined by the different TDD symbol rate. A source base station for receiving a signal in a time interval, Wherein the difference in the TDD symbol rate is the difference between the arbitrary TDD symbol rate and the different TDD symbol rate. The method of claim 15, wherein the source base station, And an interference canceller for removing a signal received in a time interval in which interference occurs due to a difference in the TDD symbol ratio from a signal received in the up-link interval. The method of claim 15, wherein the source base station, And an interference canceller configured to output a signal received in a remaining time interval except for a time interval in which interference occurs due to a difference in the TDD symbol ratio in the up-link time interval. The method according to any one of claims 16 to 17, And a service area overlapped by the counter base station and the source base station. The method according to any one of claims 16 to 17, The TDD symbol ratio is a ratio of the downlink interval and the uplink interval. The method of claim 19, And a ratio of the downlink section and the uplink section of the counterpart base station is 27:15, and the ratio of the downlink section and the uplink section of the source base station is 29:18. The method of claim 19, And a ratio of the downlink section and the uplink section of the counterpart base station is 29:18, and the ratio of the downlink section and the uplink section of the source base station is 27:15.

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