CN107294636B - A detection method and device for eliminating co-channel interference - Google Patents

Abstract

The invention discloses a detection method and device for eliminating co-frequency interference. The method includes calculating the total power of each symbol of an uplink subframe of a target base station, and determining the received signal according to the total power of each symbol and a preset threshold value. interfered symbols, and perform interference suppression processing on the demodulated data of the interfered symbols; by detecting and judging each symbol in the uplink subframe of the target base station, if it is an interfered symbol, perform interference suppression processing, effectively It can solve the problem that the overall demodulation performance of the uplink subframe is affected by the interfered symbol. At the same time, the interfered symbol is determined by calculating the total power and threshold value of the symbol, which ensures that the interfered symbol can be determined accurately. , so that the demodulated data is subjected to interference suppression processing, which further eliminates the problem that the uplink of the target base station will be interfered by the same frequency of the downlink signal of the remote base station, and also improves the demodulation performance and uplink throughput of the target base station.

Description

A detection method and device for eliminating co-channel interference

technical field

The present invention relates to the technical field of wireless network communication, and in particular, to a detection method and device for eliminating co-frequency interference.

Background technique

For a TDD (time division duplex mode) system, the base stations are required to maintain strict time synchronization. Generally, GPS synchronization is used to ensure the time timing synchronization between the base stations. Due to the way of Cao Yong's co-frequency coverage, of course there will be mutual interference between adjacent cells. At the same time, since the uplink and downlink transmissions of the TDD system share the frequency, in addition to the traditional mutual interference between adjacent cells in the TDD system, there is also a situation in which the downlink signal of the remote base station interferes with the uplink signal of the target cell.

Long-distance co-channel interference in TDD systems occurs between base stations that are far apart. As the propagation distance increases, after the signal of the far-end transmitter reaches the target base station with the same frequency at the near-end after the propagation delay, it may enter other transmission time slots of the target base station, thus affecting the normal operation of the near-end target system, as shown in Figure 1. shown. Since the transmit power of the base station is much larger than the transmit power of the terminal, the far-end co-channel interference mainly manifests as the downlink signal of the far-end cell interferes with the uplink signal reception of the near-end target base station.

Based on the current TD-LTE (Long Term Evolution) system, when the DwPTS (remote base station downlink time slot) of its special subframe is delayed to the U (uplink) subframe, the downlink signal of the remote base station will affect the target. The uplink U subframes of the base station cause strong interference, thereby degrading the uplink demodulation performance of the target base station. In the existing solution, there is no other better way to reduce the cross-slot interference between the uplink and the downlink except by increasing the GP (guard interval) between the uplink and the downlink or adjusting the inclination of the communication antenna. In addition, the above-mentioned means cannot completely eliminate the hidden trouble of such interference.

SUMMARY OF THE INVENTION

The present invention provides a detection method and device for eliminating co-frequency interference, so as to solve the technical problem that the downlink signal of the long-distance base station interferes with the uplink signal reception of the near-end target base station in the TDD system, resulting in the degradation of the uplink demodulation performance of the target base station.

In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions:

The present invention provides a detection method for eliminating co-channel interference, comprising:

Calculate the total power of each symbol of the uplink subframe of the target base station;

Determine the interfered symbol according to the total power of each symbol and a preset threshold;

Perform interference suppression processing on the demodulated data of the interfered symbols.

In another embodiment of the present invention, the threshold value is selected and set according to the demodulation performance of each symbol during uplink reception by the target base station.

In another embodiment of the present invention, performing interference suppression processing on the demodulated data of the interfered symbols specifically includes:

The demodulated data corresponding to the disturbed symbol is directly cleared to zero;

Alternatively, weighting processing is performed on the demodulated data corresponding to the disturbed symbol, and the weighting processing is to multiply the disturbed symbol by an infinitesimal value.

In another embodiment of the present invention, determining the interfered symbol according to the total power of each symbol and a preset threshold value specifically includes:

Select the total power of the first pilot symbol and the total power of all data symbols before the first pilot symbol according to the total power of each symbol of the uplink subframe;

calculating the power difference between each data symbol and the pilot symbol;

The data symbols whose power difference is greater than the threshold value are regarded as interfered symbols.

In another embodiment of the present invention, if there are multiple data symbols, first calculate the power difference between the last data symbol in the data symbols and the first pilot symbol;

comparing the power difference to the threshold;

If the power difference is greater than the threshold value, determining that all data symbols before the first pilot symbol are interfered symbols;

If the power difference is less than the threshold value, the power differences between the other data symbols and the pilot symbols are sequentially calculated and compared with the threshold value.

In order to solve the above-mentioned technical problems, the present invention also provides a detection device for eliminating co-channel interference, including:

a calculation module for calculating the total power of each symbol of the uplink subframe of the target base station;

a decision module, configured to determine the interfered symbol according to the total power of each symbol and a preset threshold value;

A processing module, configured to perform zero-clearing processing on the demodulated data of the disturbed symbols.

In another embodiment of the present invention, a setting module is further included, configured to select and set the threshold value according to the demodulation performance of each symbol during uplink reception by the target base station.

In another embodiment of the present invention, the processing module is specifically configured to directly clear the demodulated data corresponding to the disturbed symbol;

Alternatively, weighting processing is performed on the demodulated data corresponding to the disturbed symbol, and the weighting processing is to multiply the disturbed symbol by an infinitesimal value.

In another embodiment of the present invention, the determination module includes a selection sub-module, a calculation sub-module and a determination sub-module;

The selecting submodule selects the total power of the first pilot symbol and the total power of all data symbols before the first pilot symbol according to the total power of each symbol of the uplink subframe;

The calculation submodule calculates the power difference between each data symbol and the pilot symbol;

The judging submodule takes the data symbols whose power difference is greater than the threshold value as the interfered symbol.

In another embodiment of the present invention, the determination module further includes a comparison sub-module;

If there are multiple data symbols, the calculation submodule first calculates the power difference between the last data symbol in the data symbols and the first pilot symbol;

the comparison submodule compares the power difference with the threshold;

If the power difference is greater than the threshold value, the determining submodule determines that all data symbols before the first pilot symbol are interfered symbols;

If the power difference is smaller than the threshold value, the calculation sub-module sequentially calculates the power difference between the other data symbols and the pilot symbol and compares the power difference with the threshold value.

Beneficial effects of the present invention:

The present invention provides a detection method and device for eliminating co-channel interference, which determines the interfered symbols in the uplink subframe symbols of the target base station through detection, and performs zero-clearing processing on the demodulated data of the interfered symbols. The interference suppression processing is performed on the detected interfered symbols, which realizes effective, targeted and rapid processing of interfered symbols, reduces the overall impact on the subframe symbols, and improves the uplink demodulation performance of the target base station; The present invention firstly calculates the total power of each symbol of the uplink subframe of the target base station, and then determines the interfered symbol according to the total power of each symbol and the preset threshold value, and performs interference suppression processing on the symbol, through The total power of each symbol in the subframe determines the interfered symbol, and performs the interference suppression processing after demodulation. The determination processing process is simple and practical, and it also plays a good role in ensuring the overall performance of the system, and also effectively improves the The demodulation performance of the physical layer of the uplink receiving of the target base station is improved, and the throughput of the uplink receiving of the target base station is improved.

Further, after judging the interfered symbol, weighted preprocessing is performed on the interfered symbol, specifically, the data after demodulation of the interfered symbol is directly cleared to zero, or the demodulated data of the interfered symbol is processed. The data is multiplied by an infinitesimal value, so that the interfered symbol is assigned a value of 0, so that the interfered symbol is removed from the subframe symbols, and the existence of the interfered symbol that directly affects the uplink demodulation performance of the target base station is completely eliminated.

Description of drawings

Fig. 1 is a schematic diagram of a TDD system long-distance base station co-channel interfering with a short-range base station;

2 is a flowchart of a detection method for eliminating co-channel interference provided by Embodiment 1 of the present invention;

3 is a flowchart of detecting an interfered symbol and demodulating processing provided by Embodiment 2 of the present invention;

FIG. 4 is a structural block diagram of a detection apparatus for eliminating co-channel interference provided by Embodiment 3 of the present invention.

Detailed ways

The present invention will be further described in detail below through specific embodiments in conjunction with the accompanying drawings.

Example 1:

Aiming at the problem of co-frequency interference in the prior art, the present invention proposes a technical solution for eliminating co-frequency interference. By detecting and judging each symbol of the uplink subframe of the near-end target base station, the downlink with the remote base station is detected. The symbol in the uplink subframe of the target base station where the co-frequency of the signal is seriously interfered, and then the demodulated data corresponding to the interfered symbol is cleared, so as to completely eliminate the co-channel interference of the target base station from the downlink signal of the remote base station. The problem.

Please refer to FIG. 2, which is a flowchart of a detection method for eliminating co-channel interference provided by the present invention, which specifically includes the following steps:

S201, calculating the total power of each symbol of the uplink subframe of the target base station;

S202, determine the interfered symbol according to the total power of each symbol and a preset threshold value; it is worth noting that the selection and setting of the threshold value is based on the demodulation of each symbol when the target base station uplink signal is received performance to choose a setting.

S203: Perform interference suppression processing on the demodulated data of the interfered symbols.

In this embodiment, when the interfered symbol is determined according to the total power and the threshold value of each symbol, the specific operation process is as follows:

The first is to select the first pilot symbol and the total power of all data symbols before the first pilot symbol according to the total power of each symbol in the uplink subframe of the target base station. The position can be set according to the communication protocol of the target base station. Generally speaking, the position of the first pilot symbol in the subframe is determined. For example, if the number of symbols included in the subframe is 14, the first pilot symbol The set position is generally at the position of the fourth symbol; if the number of symbols included in the subframe is 12, the set position of the first pilot symbol is generally at the position of three symbols.

Then, calculate the power difference between the selected data symbol and the pilot symbol, and compare the power difference with the threshold value to determine whether the symbol is an interfered symbol;

In the above judgment process, if the power difference is greater than the preset threshold value, the data symbol corresponding to the power difference is regarded as an interfered symbol, and interference suppression processing is performed.

In this embodiment, if the number of selected data symbols is more than one, when calculating the power difference between each data symbol and the pilot symbol, the calculation and judgment method in reverse order is adopted, and the last among all data symbols is preferentially calculated. The power difference between a data symbol and the first pilot symbol, and then, the power difference is compared with the threshold value, and if the power difference is greater than the threshold value, the power difference can be directly determined The existing data symbol and all the data symbols before the data symbol are interfered symbols, and finally, the interference suppression processing is performed on the interfered symbols.

In this embodiment, in the process of judging whether the symbol is an interfered symbol, if the power difference is less than the threshold value, it is determined that the data symbol corresponding to the power difference is not affected by the downlink signal of the remote base station The interference or interference can be ignored. At this time, the power difference between the previous data symbol and the pilot symbol of the data symbol needs to be calculated in turn, and compared with the threshold value, for example: all selected data symbols include P ₀ , P ₁ and P ₂ , if the calculated power difference ΔP ₂ of P ₂ is smaller than the threshold value T, then calculate the power difference ΔP _{1 of the next data symbol P 1 ,} if the judgment result is still smaller than the threshold value, continue the calculation The power difference ΔP ₀ of the data symbol P ₀ is determined until all the data symbols are calculated or when the judgment result shows that the power difference is greater than the threshold value, the judgment operation is ended, and step S203 is executed.

In this embodiment, if it is determined that all data symbols are less than the threshold value, all data symbols are subjected to processing such as demodulation and decoding according to normal demodulation operations.

In this embodiment, the specific calculation formula for calculating the difference between the total power of each data symbol and the power of the first pilot symbol is:

ΔP _i =P _i -P ₃ ,

Among them, ΔP _i is the power difference, P _i is the total power of the symbol, P ₃ is the total power of the first pilot symbol, and i is the cyclic prefix CP (Cyclic Prefix) of the physical channel of the subframe; There are two types of frame structures: one is a normal cyclic prefix (Normal CP), and one time slot can transmit 7 OFDM (Orthogonal Frequency Division Multiplexing), that is, the seed frame structure includes 14 symbols, and at this time the uplink subframe The total power of each symbol is P _i , where i=0,1,2,...,12,13, the first pilot symbol is the fourth symbol, namely P ₃ ; another subframe structure is Extended cyclic prefix (Extended CP) can transmit 6 OFDM (Orthogonal Frequency Division Multiplexing) in one time slot, that is, the seed frame structure includes 12 symbols, and the total power of each symbol of the uplink subframe at this time is P _i , where i=0, 1, 2, ..., 10, 11, the first pilot symbol is the third symbol, namely P ₂ ;

通过上述的方式进行干扰抑制处理，有效的解决了当远端基站下行信号时隙干扰目标基站上行子帧的部分符号时解调性能较差的问题。In this embodiment, after judging and determining the interfered symbol, step S203 is performed to perform an interference suppression process on the demodulated data of the interfered symbol, and the interference suppression process includes: converting the interfered symbol The corresponding adjusted data is directly cleared to zero; or, the disturbed symbol is subjected to weighting processing, and the weighting processing is to multiply the disturbed symbol by an infinitesimal value, optionally, the infinitesimal value. The value of can be

By performing the interference suppression processing in the above manner, the problem of poor demodulation performance when the downlink signal time slot of the remote base station interferes with some symbols of the uplink subframe of the target base station is effectively solved.

Embodiment 2:

Please refer to FIG. 3 . FIG. 3 is a specific processing flow chart of detecting disturbed symbols and demodulating processing in this embodiment. The processing steps include:

S301, calculate the total power P _i (dB) of each symbol of the uplink subframe of the target base station, for the subframe structure of the general cyclic prefix, its i=0, 1, 2, 3, ..., 12, 13; for the extended cyclic prefix The subframe structure of the prefix, its i=0,1,2,...,10,11;

S302, calculate the power difference ΔP _i between the data symbol before the first pilot and the first pilot symbol, and the calculation formula is: ΔP _i =P _i -P ₃ , where ΔP _i is the power difference, and P _i is The total power of the symbol, _P3 is the total power of the first pilot symbol;

For Normal CP, its power difference ΔP _i =P _i -P ₃ , i=0,1,2; for Extended CP, its power difference ΔP _i =P _i -P ₃ , i=0,1;

S303, judging the magnitude relationship between the power difference ΔP _i and the threshold value T, and judging whether the power difference ΔP _i is greater than the threshold value T, if yes, execute steps S304 and S305; otherwise, execute S306.

S304, demodulate the symbol to obtain demodulated data;

使得该符号为无穷大的值，也即是处理为0。S305, performing zero-clearing processing on the demodulated data, and the interference suppression processing specifically includes the following methods: directly performing zero-clearing processing on the demodulated data, or performing weighting processing on the demodulated data of the symbol, multiplying by

Make the symbol an infinite value, that is, treat it as 0.

S306, perform normal demodulation processing on the symbol to obtain the corresponding demodulated data symbol;

S307, performing decoding processing on the data symbol or the weighted preprocessed data symbol;

S308, perform CRC (Cyclic Redundancy Code, cyclic redundancy code check) processing on the data decoded in step S307.

In this embodiment, preferably, taking Normal CP as an example, the first pilot symbol is P ₃ , the threshold value T is set to 10dB, and the interfered symbols are three data symbols before the first pilot symbol , the specific processing steps are as follows:

First, calculate the total power P _i of each symbol of the uplink U subframe, respectively:

[-98,-99,-100,-113,-113.5,-114,-113.3,-113,-113.2,-113.1,-113.6,-113,-112.8,-112.9];

Then, according to the total power of each data symbol, the power difference ΔP _i between it and the first pilot symbol is calculated, and the calculation results are: [15, 14, 13];

Further, compare the calculated power difference ΔP _i with the threshold value T, if the comparison result is ΔP ₂ >T, then determine that all the first three symbols are not greater than the threshold value T, otherwise continue to calculate and compare ΔP ₁ , ΔP ₀ and the size of the threshold value T;

Finally, according to the judgment result, the interference suppression processing is performed on the demodulated data of the interfered symbols, that is, the demodulation results corresponding to the three judged symbols are cleared to 0, or multiplied by an infinitesimal value. , as multiplied by

For Extended CP, first, calculate the total power P _i of each symbol of the uplink U subframe, respectively:

[-97.6,-98.2,-113.5,-114,-113.3,-113,-113.2,-113.1,-113.6,-113,-112.8,-112.9];

Calculate the power difference ΔP _i with the first pilot symbol according to the total power of each data symbol, and the calculation results are: [15.9, 15.3];

Further, compare the calculated power difference ΔP _i with the threshold value T, if the comparison result is ΔP ₁ >T, then determine that the first two symbols are all not greater than the threshold value T, otherwise continue to calculate and compare ΔP ₀ with the threshold value T. The size of the limit value T;

Finally, according to the judgment result, the interference suppression processing is performed on the demodulated data of the disturbed symbols, and the demodulated results corresponding to the three judged symbols are cleared to 0, or multiplied by an infinitesimal value. ,like

Embodiment three:

Please refer to FIG. 4. FIG. 4 is a block diagram of the structure of the detection device for eliminating co-channel interference provided in this embodiment. It should be understood that the device can be set in any base station, so as to solve the problem that the target base station will receive The problem of co-channel interference of downlink signals of remote base stations is shown in FIG. 4 . The detection device 40 for eliminating co-channel interference provided in this embodiment includes: a calculation module 401 , a determination module 402 and a processing module 403 ;

The calculating module 401 is used to calculate the total power of each symbol of the uplink subframe of the target base station;

The determining module 402 is configured to determine the interfered symbol according to the total power of each symbol and a preset threshold;

The processing module 403 is configured to perform interference suppression processing on the demodulated data of the interfered symbols.

In this embodiment, the apparatus further includes a setting module 404, configured to select and set the threshold value according to the demodulation performance of each symbol during uplink reception by the target base station.

In this embodiment, the determination module 402 includes a selection sub-module 4021, a calculation sub-module 4022 and a determination sub-module 4023;

The selecting submodule 4021 selects the total power of the first pilot symbol and the total power of all data symbols before the first pilot symbol according to the total power of each symbol of the uplink subframe;

The calculation submodule 4022 calculates the power difference between each data symbol and the pilot symbol;

The determination sub-module 4023 regards the data symbols whose power difference is greater than the threshold value as the interfered symbol.

In this embodiment, the calculation formula for calculating the power difference by the calculation sub-module 4022 is:

ΔP _i =P _i -P ₃ ,

Among them, ΔP _i is the power difference, P _i is the total power of the symbol, P ₃ is the total power of the first pilot symbol, and i is the cyclic prefix CP of the physical channel of the subframe. Generally speaking, the subframe structure includes two species, according to different subframe structures, the value of i is also different;

In this embodiment, the determination module 402 further includes a comparison sub-module 4024; if there are multiple data symbols, the calculation sub-module 4022 first calculates the last data symbol and the first pilot symbol in the data symbols power difference;

The comparison sub-module 4024 compares the power difference with the threshold;

If the power difference is greater than the threshold value, the determination sub-module 4023 determines that all data symbols before the first pilot symbol are disturbed symbols;

If the power difference is smaller than the threshold value, the calculation sub-module 4021 calculates the power difference between other data symbols and the pilot symbol in sequence and compares the power difference with the threshold value.

Preferably, in this embodiment, when calculating the power difference between each data symbol and the pilot symbol, a calculation and judgment method in reverse order is adopted. For example, all the selected data symbols include P ₀ , P ₁ and P ₂ . If When the power difference ΔP ₂ of the calculated P ₂ is less than the threshold value T, calculate the power difference ΔP _{1 of the next data symbol P 1 ,} and if the judgment result is still less than the threshold value, continue to calculate the power difference of the data symbol P ₀ ΔP ₀ , until all data symbols are calculated or when the power difference is greater than the threshold value in the judgment result, the judgment operation is ended, and the zero-clearing process is performed on the interfered symbols.

If after the judgment, all the data symbols are smaller than the threshold value, the processing module 403 performs normal mediation processing on all the data symbols.

In this embodiment, after the device 40 determines that the symbol is an interfered symbol, the processing module 403 performs interference suppression zero processing on the demodulated data of the interfered symbol according to the judgment result, and the interference suppression The processing includes: directly clearing the demodulated data corresponding to the symbol;

Or, perform weighting processing on the disturbed symbols, and the weighting processing is to multiply the disturbed symbols by an infinitesimal value, preferably, multiplying by

To sum up, the detection method and device for eliminating co-channel interference provided by the present invention is to determine whether it is interfered by the downlink signal of the remote base station by detecting and judging each symbol of the uplink subframe of the target base station, and further, It is to calculate the total power of each symbol, determine the interfered symbol in combination with the preset threshold value, and perform interference suppression processing on the demodulated data of the interfered symbol, which is realized by the detection method provided by the present invention. It is relatively easy to eliminate co-channel interference and detect the total power of each symbol, so that the implementation process of the method is simple and practical, and at the same time, the overall performance of the system can be guaranteed; the method provided by the present invention can effectively improve the current part of the data symbols. The problem of demodulation performance degradation under severe interference improves the uplink throughput of the target base station.

Obviously, those skilled in the art should understand that each module or each step of the present invention can be implemented by a general-purpose computing device, and they can be centralized on a single computing device or distributed on a network composed of multiple computing devices , optionally, they can be implemented with program code executable by a computing device, so that they can be stored in a storage medium (ROM/RAM, magnetic disk, optical disk) for execution by the computing device, and in some cases , the steps shown or described may be performed in a different order than herein, either by fabricating them separately into individual integrated circuit modules, or by fabricating multiple modules or steps of them into a single integrated circuit module. Therefore, the present invention is not limited to any particular combination of hardware and software.

The above content is a further detailed description of the present invention in conjunction with specific embodiments, and it cannot be considered that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field of the present invention, without departing from the concept of the present invention, some simple deductions or substitutions can be made, which should be regarded as belonging to the protection scope of the present invention.

Claims (8)

1. A detection method for eliminating co-channel interference is characterized by comprising the following steps:

calculating the total power of each symbol of an uplink subframe of a target base station;

determining interfered symbols according to the total power of each symbol and a preset threshold value; the determining the interfered symbol according to the total power of each symbol and the preset threshold specifically includes:

selecting the total power of a first pilot frequency symbol and the total power of each data symbol before the first pilot frequency symbol according to the total power of each symbol of an uplink subframe;

calculating the power difference between each data symbol and the first pilot frequency symbol;

taking the data symbol with the power difference larger than the threshold value as an interfered symbol;

and carrying out interference suppression processing on the data after the interfered symbol demodulation.

2. The detection method for eliminating co-channel interference according to claim 1, wherein the threshold value is selectively set according to demodulation performance of each symbol when the target base station receives uplink.

3. The method according to claim 1, wherein the interference suppression processing on the data demodulated by the interfered symbol specifically comprises:

directly carrying out zero clearing processing on the demodulated data corresponding to the interfered symbol;

or, performing weighting processing on the demodulated data corresponding to the interfered symbol, where the weighting processing is to multiply the interfered symbol by an infinitesimal value.

4. The detection method for eliminating co-channel interference according to claim 1, wherein if there are a plurality of data symbols, the power difference between the last data symbol in the data symbols and the first pilot symbol is calculated first;

comparing the power difference to the threshold value;

if the power difference is larger than the threshold value, all data symbols before the first pilot frequency symbol are determined to be interfered symbols;

and if the power difference is smaller than the threshold value, calculating the power difference between other data symbols and the first pilot frequency symbol in a reverse order and comparing the power difference with the threshold value.

5. A detection device for eliminating co-channel interference is characterized by comprising:

the calculation module is used for calculating the total power of each symbol of an uplink subframe of the target base station;

the judging module is used for determining the interfered symbol according to the total power of each symbol and a preset threshold value; the judgment module comprises a selection submodule, a calculation submodule and a judgment submodule;

the selection submodule selects the total power of the first pilot frequency symbol and the total power of each data symbol before the first pilot frequency symbol according to the total power of each symbol of the uplink subframe;

the calculation submodule calculates the power difference between each data symbol and the first pilot frequency symbol;

the judgment sub-module takes the data symbol with the power difference larger than the threshold value as an interfered symbol;

and the processing module is used for carrying out interference suppression processing on the data after the interfered symbol is demodulated.

6. The apparatus of claim 5, further comprising a setting module, configured to select and set the threshold according to the demodulation performance of each symbol when the target base station receives uplink.

7. The apparatus according to claim 5, wherein the processing module is specifically configured to directly perform zero clearing on the demodulated data corresponding to the interfered symbol;

or, performing weighting processing on the demodulated data corresponding to the interfered symbol, where the weighting processing is to multiply the interfered symbol by an infinitesimal value.

8. The apparatus for eliminating co-channel interference according to claim 5, wherein the decision module further comprises a comparison sub-module;

if the number of the data symbols is multiple, the calculation submodule calculates the power difference between the last data symbol in the data symbols and the first pilot frequency symbol;

the comparison submodule compares the power difference with the threshold value;

if the power difference is larger than the threshold value, the judgment sub-module determines that all data symbols before the first pilot frequency symbol are interfered symbols;

and if the power difference is smaller than the threshold value, the calculation sub-module calculates the power difference between other data symbols and the first pilot frequency symbol in a reverse order and compares the power difference with the threshold value.

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