CN109842457B - Atmospheric waveguide interference suppression method and system - Google Patents
Atmospheric waveguide interference suppression method and system Download PDFInfo
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Abstract
The invention provides an atmospheric waveguide interference suppression method and a system, wherein the method comprises S1, obtaining the time delay of co-frequency interference after determining that the interference suffered by an interfered cell is the co-frequency interference, and determining the co-frequency interference of which the time delay exceeds a set time delay threshold value as the atmospheric waveguide interference; s2, synchronizing with the interference signal interfered by the atmospheric waveguide to obtain a Physical Cell Identity (PCI) of an interference source cell generating the atmospheric waveguide interference, periodically monitoring a System Information Block (SIB) message of the interference source cell to obtain global identifier (ECGI) information of the interference source cell, and determining the position of the interference source cell according to the ECGI information; and S3, dividing the interfered cell into different area ranges by taking the interfered core site as a concentric circle according to the position relation between the interfered cell and the interference source cell, and respectively carrying out interference suppression on each area range. The suppression of the same frequency interference of the TD-LTE far end at the interfered end is realized.
Description
Technical Field
The present invention relates to the field of communications technologies, and in particular, to an atmospheric waveguide interference suppression method and system.
Background
Under certain meteorological conditions, electromagnetic waves propagating in an atmospheric boundary layer, particularly a near stratum, are influenced by atmospheric refraction, the propagation track of the electromagnetic waves bends to the ground, and when the curvature exceeds the curvature of the earth surface, the electromagnetic waves are partially trapped in an atmospheric thin layer with a certain thickness, just like the electromagnetic waves propagate in a metal waveguide tube, and the phenomenon is called atmospheric waveguide propagation of the electromagnetic waves. The atmospheric waveguide phenomenon can enable TD-LTE downlink wireless signals to be transmitted far, and the transmission distance exceeds the protection distance of an uplink protection time slot (GP) and an downlink protection time slot (GP) of a TD-LTE system, so that the remote TD-LTE downlink wireless signals interfere with local TD-LTE uplink wireless signals.
In the TD-LTE wireless field, if the wireless propagation environment between an interfering station and an interfered station is very good, it can be equivalent to free space. When a long-distance station signal is propagated to reach an interfered station, attenuation is small because of good propagation environment, and meanwhile, a downlink signal of the interfering station is aligned with an uplink signal of the interfered station (seriously and even falls into an uplink subframe of the interfered station) because of time delay in the propagation process, so that a base station of the interfering station sends interference to a base station of the interfered station.
As shown in fig. 1, DwPTS is a downlink protection timeslot, UpPTS is an uplink protection timeslot, and GP is a protection interval, which is mainly used for protection during downlink-to-uplink conversion; during cell search, reliable reception of DwPTS is ensured, and UL interference is prevented; at the time of random access, the UpPTS can be ensured to be transmitted in advance, and interference DL is prevented. The GP in a special subframe determines the minimum distance that the DL will not interfere with the UL.
In the prior art, three main methods are currently adopted for the TD-LTE atmospheric waveguide interference judgment method; the method comprises the following steps: analyzing based on disturbed RB of a disturbed base station; according to the difference between the characteristics of the traditional co-channel interference and the characteristics of the remote co-channel interference, if the uplink of a disturbed base station (PUSCH disturbed) is interfered by the co-channel interference of an adjacent cell, all subcarriers and OFDM symbols on the uplink disturbed RB of the disturbed cell are interfered; if the interference is the long-distance same frequency interference, the time domain position and the distance of the long-distance signal reaching the local interfered base station are related, so that the time domain OFDM symbols of the uplink interfered RB are not necessarily all interfered, along with the increase of the interference distance, the OFDM symbols from left to right in the time domain are sequentially interfered, and the interference intensity tends to decrease from left to right. And carrying out specific analysis on interfered symbols in the interfered RB, and if the interfered RB is an OFDM symbol from left to right, sequentially interfering, preliminarily judging that the interfered cell is subjected to remote co-channel interference. The second method comprises the following steps: based on the interaction of PRACH and uplink scheduling information of the adjacent base station; through an X2 interface, a victim cell may interact with neighboring cells for PRACH and uplink scheduling information of respective base stations. If the interfered cell knows that the adjacent cell base station does not allocate the resource of the frequency band in the interfered time slot through the information interaction of the X2 interface, the adjacent cell base station does not generate interference on the interfered time slot of the interfered cell, and the interference on the adjacent cell base station can be preliminarily judged to be remote co-channel interference. The third method comprises the following steps: analyzing the disturbed condition based on the central frequency of the disturbed base station; if the distance of the long-distance co-channel interference is far enough, the interference of P-SCH (primary synchronization signal), S-SSH (secondary synchronization signal) and even PBCH (physical broadcast channel) signals of a far base station to the uplink of a near base station is caused, and according to the characteristics of the channel signals, the frequency region of the central 1.08MHz bandwidth of a near interfered base station can be known to be interfered relatively constantly. In addition, if the frequency domain of the PRACH of the interfered base station occupies the center 1.08MHz, it may be that the terminal is always sending the preamble code, so the method needs to determine the interference condition of the center 1.08MHz and the frequency domain position allocated to the PRACH at the same time.
When the PRACH of the interfered base station does not occupy the center 1.08MHz, the signal of the interfered base station is analyzed, and if the frequency area of the center 1.08MHz bandwidth of the interfered base station is subjected to constant interference, the interfered base station can be preliminarily judged to be subjected to the same frequency interference at the ultra-long distance. For the method I, the interfered RB analysis based on the interfered base station has the problems of large calculated amount and inaccurate positioning of an interference source; the second method is based on the interaction between the PRACH of the adjacent base station and the uplink scheduling information, and because the dynamic scheduling change of the base station is too fast, the method really takes effect and has more constraint and limiting conditions, and the operability of the practical algorithm application is poor; the third method is based on the analysis of the disturbed condition of the central frequency of the disturbed base station, and relates to the uncertainty of the frequency domain position distributed by the PRACH and the poor interference positioning accuracy.
Disclosure of Invention
The invention provides an atmospheric waveguide interference suppression method and system for overcoming the problems or at least partially solving the problems, and solves the problems of large calculation amount, inaccurate interference source positioning, more limiting conditions and poor operability in the prior art.
According to an aspect of the present invention, there is provided an atmospheric waveguide interference suppression method, including:
s1, obtaining the time delay of the same frequency interference after determining that the interference suffered by the interfered cell is the same frequency interference, and determining the same frequency interference of which the time delay exceeds a set time delay threshold value as atmospheric waveguide interference;
s2, synchronizing with the interference signal interfered by the atmospheric waveguide to obtain a Physical Cell Identity (PCI) of an interference source cell generating the atmospheric waveguide interference, periodically monitoring a System Information Block (SIB) message of the interference source cell to obtain global identifier (ECGI) information of the interference source cell, and determining the position of the interference source cell according to the ECGI information;
and S3, dividing the interfered cell into different area ranges by taking the interfered core site as a concentric circle according to the position relation between the interfered cell and the interference source cell, and respectively carrying out interference suppression on each area range.
Preferably, the step S1 specifically includes:
monitoring the interference condition of a Physical Resource Block (PRB) of a cell, and if the intensity of an interference signal received by the cell exceeds a set interference threshold, judging the cell to be an interfered cell;
carrying out same frequency judgment on interference signals of the interfered cell, if the interference signals are the same frequency interference, obtaining the time delay of the same frequency interference, and carrying out time delay judgment on the interference signals to obtain the time delay required by the transmission of the interference signals of the same frequency interference to the interfered cell;
and if the time delay exceeds a set time delay threshold value, judging that the same frequency interference is atmospheric waveguide interference.
Preferably, the obtaining the time delay of the co-channel interference includes:
obtaining interference sweep frequency data of an Orthogonal Frequency Division Multiplexing (OFDM) symbol level of an interfered cell, judging that the same frequency interference has no time delay if all OFDM symbols are interfered, and obtaining the time delay of the same frequency interference according to the last interfered OFDM symbol if not all OFDM symbols are interfered.
Preferably, the step S3 further includes:
searching interference frequency band and frequency point information of an interference source cell, and carrying out frequency error on the interference source cell and an interfered cell; or
And adjusting the direction angle and the downward inclination angle of the electrically-adjusted antenna, and performing directional avoidance by combining the distance and the angle between the interfered cell and the interference source cell.
Preferably, the step S3 specifically includes:
calculating the difference OFDM symbol number X between the disturbed core station and the interference signal according to the time delay;
if X is less than or equal to 9, the special subframe ratio of the interfered cell and the interference source cell is jointly modified to 3:9: 2;
and if X is larger than 9, taking the interfered core station as a concentric circle, dividing the interfered cell into different area ranges, and performing interference suppression processing on the interfered base station and the nearby base station in the divided area ranges.
Preferably, in step S3, taking the interfered core station as a concentric circle, dividing the interfered cell into different area ranges includes:
determining an interference area interfered by atmospheric waveguide caused by the same interference source cell, making a boundary ellipse according to the boundary of the interference area, enabling the long axis of the boundary ellipse to be parallel to the interference direction and the short axis to be perpendicular to the interference direction, and calculating the positions of two focuses of the boundary ellipse;
taking a focus far away from an interference source cell in the boundary ellipse as a common focus, and making an ellipse layer by layer from inside to outside in the boundary ellipse so as to divide an interference area into different area ranges; wherein, the number Y of the ellipses is X/9, and the Y is rounded up; the radius of the long axis of the nth ellipse from inside to outside in the boundary ellipse is n (a/Y), n is less than or equal to Y, and a is the radius of the long axis of the boundary ellipse.
Preferably, in step S3, the performing, in the divided area ranges, interference suppression processing on the interfered base station and the neighboring base stations specifically includes:
adjusting the interfered cells in each layer of ellipse through frame header frequency offset deviation, and then delaying the time slot reference of the interfered cells to avoid atmospheric waveguide interference;
if the frame head adjustment amplitude of the interfered cell in the elliptical layer exceeds the GP protection interval of the cell outside the elliptical layer, the cell outside the elliptical layer adopts a radiation gradual change algorithm according to the number of the interval layers with the elliptical layer, and simultaneously performs frame head adjustment so as to enable the interfered cell in the elliptical layer and the cell outside the elliptical layer to be free from interference.
Preferably, the adjusting of the frame header of the cell outside the elliptical layer by using a radiation gradual change algorithm according to the number of the spacing layers between the cell and the elliptical layer specifically comprises:
the frame head of the interfered cell in the oval layer in the boundary oval is adjusted from inside to outside, the frame head of the interfered cell in the oval layer at the innermost layer is moved backwards by 9 OFDM symbols, and in each two adjacent oval layers, the frame head of the interfered cell in the oval layer at the outer layer is moved backwards by 9 OFDM symbols based on the frame head of the interfered cell in the oval layer at the inner layer.
An atmospheric waveguide interference suppression system comprising:
the atmospheric waveguide interference judgment module is used for obtaining the time delay of the same frequency interference after determining that the interference suffered by the interfered cell is the same frequency interference, and determining the same frequency interference of which the time delay exceeds a set time delay threshold value as the atmospheric waveguide interference;
an interference source cell determining module, configured to synchronize with an interference signal interfered by the atmospheric waveguide, to obtain a physical cell identity PCI of an interference source cell that generates the atmospheric waveguide interference, and periodically monitor a system information block SIB message of the interference source cell, to obtain an global identifier ECGI information of the interference source cell, and determine a location of the interference source cell according to the ECGI information;
and the interference suppression module is used for dividing the interfered cell into different area ranges by taking the interfered core station as a concentric circle according to the position relation between the interfered cell and the interference source cell, and performing interference suppression on each area range respectively.
Preferably, the interference suppression module is further configured to retrieve interference frequency band and frequency point information of the interference source cell, and perform frequency error on the interference source cell and the interfered cell; or
And adjusting the direction angle and the downward inclination angle of the electrically-adjusted antenna, and performing directional avoidance by combining the distance and the angle between the interfered cell and the interference source cell.
The invention provides an atmospheric waveguide interference suppression method and system, which monitor system information of an interference source cell through interference source synchronization, thereby obtaining information such as ECGI (echo cancellation index) of the interference cell, accurately positioning TD-LTE (time division-Long term evolution) far-end co-frequency interference without sending an identifier by additional resources, realizing accurate judgment and positioning operation of the interference, saving a large amount of manpower processes, and improving the positioning accuracy difference of the interference source in the existing scheme; meanwhile, specific information (such as distance, subframe ratio, frame header frequency offset and the like) of an interference source cell is combined to divide a concentric oval region to perform interference suppression processing on an interfered base station and a nearby base station to obtain an optimal interference suppression scheme, so that suppression of TD-LTE remote co-frequency interference at an interfered end is realized, the problem of compatibility and matching of different manufacturers does not exist, and assistance of the interference source side is not needed.
Drawings
Fig. 1 is a schematic diagram illustrating a principle of interference generation of a base station in the prior art;
FIG. 2 is a flow chart of an atmospheric waveguide interference suppression method according to an embodiment of the invention;
FIG. 3 is a schematic flow chart of an atmospheric waveguide interference suppression method according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of an automatic adjusting method of frequency offset of a radial gradient frame header according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of the interference intensity of the atmospheric waveguide according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of the interference intensity of the atmospheric waveguide adjusted by the method of the present invention according to the embodiment of the present invention.
Detailed Description
The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
As shown in fig. 2 and 3, an atmospheric waveguide interference suppression method is shown, which includes:
s1, obtaining the time delay of the same frequency interference after determining that the interference suffered by the interfered cell is the same frequency interference, and determining the same frequency interference of which the time delay exceeds a set time delay threshold value as atmospheric waveguide interference;
s2, synchronizing with the interference signal interfered by the atmospheric waveguide to obtain a Physical Cell Identifier (PCI) of an interference source Cell generating the atmospheric waveguide interference, periodically monitoring a System Information Block (SIB) message of the interference source Cell to obtain Global Identifier (E-UTRAN Cell Global Identifier, ECGI) Information of the interference source Cell, and determining the position of the interference source Cell according to the ECGI Information;
and S3, dividing the interfered cell into different area ranges by taking the interfered core site as a concentric circle according to the position relation between the interfered cell and the interference source cell, and respectively carrying out interference suppression on each area range.
In this embodiment, the interfered cell may be an interfered base station, and the interference source cell may also be an interference source base station.
The atmospheric waveguide phenomenon can extend the transmission distance of electromagnetic waves, so that the transmission distance is several times longer than the normal propagation distance, and therefore, long-distance co-frequency interference mentioned in the communication system can occur.
Specifically, in this embodiment, the step S1 specifically includes:
monitoring the interference condition of a Physical Resource Block (PRB) of a cell, and determining whether the interference received by the cell reaches a certain degree, that is, if the interference signal strength exceeds a set interference threshold, determining that the cell is an interfered cell.
And carrying out co-frequency judgment on interference signals received by the interfered cell, and carrying out other interference investigation if the interference signals are not co-frequency.
When the interfered cell of the time waiting same Frequency interference, further test judgment is needed, the Frequency spectrum is scanned according to the symbol level of the OFDM (Orthogonal Frequency Division Multiplexing) of the interfered cell (base station sector) for analysis, if all the OFDM symbols are interfered, namely no time delay is existed, the close-range same Frequency interference is checked, if not all the OFDM symbols are interfered, the transmission time delay needed for transmitting the interference signal of the far-end interference source cell to the interfered cell can be obtained according to the last interfered OFDM symbol; and preliminarily judging that the co-frequency interference with larger transmission delay is atmospheric waveguide interference, namely judging that the co-frequency interference is the atmospheric waveguide interference if the delay exceeds a set delay threshold.
The LTE system message SIB1 is sent by using an independent RRC message and is sent on a transmission channel DL SCH, and the scheduling period is fixed to 80 ms. Transmission starts at subframe 5 of the radio frame with SFN MOD 8 ═ 0, and repeats at the end of each period, subframe 5 of the radio frame with SFN MOD 2 ═ 0, which contains CELL IDENTITY information of the serving cell. As shown in the table below, the description of the SIB1 information element in the 36.331 protocol is provided.
In this embodiment, the step S2 specifically includes:
an interfered base station starts a related detection algorithm of an interference signal by using the transmission delay of an interference source cell acquired by OFDM interference sweep frequency, synchronizes with the interference signal interfered by the atmospheric waveguide to acquire a physical cell identifier PCI of the interference source cell generating the atmospheric waveguide interference, periodically monitors a system information block SIB message of the interference source cell to acquire a global identifier ECGI information of the interference source cell, and determines the position of the interference source cell according to the ECGI information. By obtaining the interference distance and the ECGI information of the interference source cell, reporting to an MME (Mobility Management Entity, Mobility Management node function), and analyzing to obtain the location information of the interference source cell, where the location information at least includes a cell name, longitude and latitude, a frequency point, a frequency band, and a bandwidth.
And further acquiring the information of the interference source cell from the cell information of the Chinese area according to the position information of the interference source cell, wherein the cell information at least comprises a cell name, longitude and latitude, frequency points, frequency bands, bandwidths and the like.
According to the distance between the interfered cell and the interference source cell, the conventional measure for determining far-end interference is that the interference of the atmospheric waveguide mostly relates to a cell far away from the interference source cell, and the adjustment of the interference source cell is often more difficult, so in the embodiment, a scheme for performing interference suppression on the side base station interfered by the atmospheric waveguide is provided.
When the calculated interference distance is less than 186KM, the ratio of the special subframes is modified to 3:9:2 by the interfered cell and the interference source cell together, so as to prevent mutual interference; only the interferer base station special timeslot proportion may be modified for the uni-directional interference.
From a theoretical perspective, the TD-LTE network adopts a Time Division Duplex (TDD) mode, that is, the reception and transmission of signals are completed in the same frequency band, and uplink signals and downlink signals are respectively transmitted in different Time periods of the same Time axis. There are three subframe structures in the TD-LTE frame structure, which are an uplink subframe, a downlink subframe, and a special subframe, where the special subframe is composed of DwPTS (downlink timeslot), GP (Guard Interval), and UpPTS (uplink timeslot). The GP is only responsible for providing a guard interval for the uplink and downlink to prevent "cross interference" and does not transmit any type of signal.
The following table shows the guard distances for different sub-frame ratios.
The protection distance can be calculated according to the length of the special subframe GP in the table, and the protection distance is from 21.4km to 214.3 km. When the radio propagation environment between base stations is good and GP of the configured special subframe is small, TDD super-far interference is likely to be caused.
In the protocol 3GPP 36.211, it is mentioned that (NTA + NTAoffset) × Ts is used as the uplink transmission time, where NTAoffset is fixed to 624 Ts, and the uplink transmission time obtained by substituting the formula is 1/30720 × 624 ═ 20.3125 μ s.
Calculating the farthest base station distance S supported by the GP guard interval:
S＝t*C＝{(X/14)*1000–20.3125}*C
wherein, C is the light speed, and X is the number of symbols of the special subframe GP. When the special subframe ratio is 3:9:2, X is 9, and S is calculated to be 186 km.
In this embodiment, when the calculated interference distance is greater than 186KM, the suppression scheme includes:
(1) and carrying out frequency error on the interference source and the interfered base station according to the interference source frequency band and the frequency point information retrieved from the cloud platform, so as to ensure that the two ends are completely different in frequency.
(2) The directional evasion is carried out by combining the distance, the angle and the like between the electrically-adjusted antenna and the directional evasion.
(3) And adopting a scheme of automatically adjusting the frequency offset of the radiation type gradient frame head.
Because the atmospheric waveguide has directivity, and generally performs diffusion extension from one direction, the disturbed region can be simulated by an ellipse, and the frequency offset is automatically adjusted by adopting the radiation type gradient frame head. Calculating the difference of the interfered core site and the interference signal by OFDM symbol number X according to time delay, modifying the special subframe ratio to 3:9:2 for interference elimination when X is less than or equal to 9, performing further calculation when X is greater than 9, dividing the interfered cell into different area ranges by taking the interfered core site as a concentric circle, and performing interference suppression processing on the interfered base station and nearby base stations by the divided area ranges.
Specifically, when an interfered cell is divided, an interference area interfered by atmospheric waveguide caused by the same interference source cell is determined, a boundary ellipse is made according to the boundary of the interference area, the long axis of the boundary ellipse is parallel to the interference direction, the short axis of the boundary ellipse is perpendicular to the interference direction, and the positions of two focuses of the boundary ellipse are calculated.
Specifically, as shown in FIG. 4, the rootAccording to the distribution condition of interfered cells, taking 4 sites under an interfered boundary ellipse model as 4 end points of a major axis and a minor axis of an ellipse, namely acquiring the interfered condition of each cell, determining base station areas (namely, an outermost ellipse in figure 2) causing atmospheric waveguide interference by the same far-end base station, selecting edge base stations in the areas as the end points, determining a major axis and a minor axis of the ellipse according to end point connecting lines, enabling the major axis to be parallel to the interference direction, enabling the minor axis to be vertical to the interference direction, calculating the positions of two focuses of the ellipse according to the major axis radius and the minor axis radius, wherein the major axis radius of the ellipse is b, the minor axis radius is a, the focus is on an x axis, the focus is +/-c, the focus is on a y axis, the focus is (0, +/-c), and the focus
Taking a focus of the boundary ellipse far from the interference source cell as a common focus, and making ellipses layer by layer from inside to outside in the boundary ellipse so as to divide an interference region into different region ranges; wherein, the number Y of the ellipses is X/9, and the Y is rounded up; after the focus is determined, the major axis radius of each ellipse is calculated, and the major axis radius an of the nth ellipse from inside to outside in the boundary ellipse is n (a/Y), which specifically includes: a1 ═ a/Y, a2 ═ 2 (a/Y), …, an ═ n (a/Y), n ≦ Y, and a is the major axis radius of the boundary ellipse.
Adjusting the interfered cells in each layer of ellipse through frame header frequency offset deviation, and then delaying the time slot reference of the interfered cells to avoid atmospheric waveguide interference;
if the frame head adjustment amplitude of the interfered cell in the elliptical layer exceeds the GP protection interval of the cell outside the elliptical layer, the cell outside the elliptical layer adopts a radiation gradual change algorithm according to the number of the interval layers with the elliptical layer, and simultaneously performs frame head adjustment so as to enable the interfered cell in the elliptical layer and the cell outside the elliptical layer to be free from interference.
Specifically, as shown in fig. 4, when 2 ≧ Y >1, the station in the first elliptic layer is shifted backward by 9 OFDM symbols, the station in the second elliptic layer is shifted backward by X-9 OFDM symbols, when 3 ≧ Y >2, the station in the first elliptic layer is shifted backward by 9 OFDM symbols, the station in the second elliptic layer is shifted backward by 9 OFDM symbols, the station in the third elliptic layer is shifted backward by X-18 OFDM symbols, and so on. And the influence of atmospheric waveguide interference is gradually eliminated in the interference measurement, and the atmospheric waveguide interference elimination is realized under the condition of losing a small amount of resources by synchronously combining symbol turn-off.
As shown in fig. 5 and 6, before and after the interference is adjusted to improve the comparison, the interference is reduced from about-90 to-117 when the interference is strongest as shown by a solid line in the figure.
The embodiment also provides an atmospheric waveguide interference suppression system, which comprises:
the atmospheric waveguide interference judgment module is used for obtaining the time delay of the same frequency interference after determining that the interference suffered by the interfered cell is the same frequency interference, and determining the same frequency interference of which the time delay exceeds a set time delay threshold value as the atmospheric waveguide interference;
an interference source cell determining module, configured to synchronize with an interference signal interfered by the atmospheric waveguide, to obtain a physical cell identity PCI of an interference source cell that generates the atmospheric waveguide interference, and periodically monitor a system information block SIB message of the interference source cell, to obtain an global identifier ECGI information of the interference source cell, and determine a location of the interference source cell according to the ECGI information;
and the interference suppression module is used for dividing the interfered cell into different area ranges by taking the interfered core station as a concentric circle according to the position relation between the interfered cell and the interference source cell, and performing interference suppression on each area range respectively.
In this embodiment, the interference source cell determining module is disposed on a cloud platform, and cell information of the china area is stored in the cloud platform and updated every day according to configuration in the network manager. The method comprises the steps of obtaining an interference distance and ECGI (evolution-initiative) information of an interference source cell, reporting to an MME (Mobility Management Entity), and analyzing by a cloud platform to obtain the position information of the interference source cell, wherein the position information at least comprises a cell name, longitude and latitude, a frequency point, a frequency band and a bandwidth.
In this embodiment, the interference suppression module is further configured to retrieve interference frequency band and frequency point information of an interference source cell, and perform frequency error on the interference source cell and an interfered cell; or
And adjusting the direction angle and the downward inclination angle of the electrically-adjusted antenna, and performing directional avoidance by combining the distance and the angle between the interfered cell and the interference source cell.
In summary, the invention provides an atmospheric waveguide interference suppression method and system, which monitor system information of an interference source cell through interference source synchronization, thereby obtaining information such as ECGI of the interference cell, and accurately positioning TD-LTE remote co-frequency interference without sending an identifier by additional resources, so as to realize accurate judgment and positioning operation of interference, save a large amount of manpower processes, and improve positioning accuracy difference of the interference source in the existing scheme; meanwhile, specific information (such as distance, subframe ratio, frame header frequency offset and the like) of an interference source cell is combined to divide a concentric oval region to perform interference suppression processing on an interfered base station and a nearby base station to obtain an optimal interference suppression scheme, so that suppression of TD-LTE remote co-frequency interference at an interfered end is realized, the problem of compatibility and matching of different manufacturers does not exist, and assistance of the interference source side is not needed.
Finally, the method of the present invention is only a preferred embodiment and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. An atmospheric waveguide interference suppression method, comprising:
s1, obtaining the time delay of the same frequency interference after determining that the interference suffered by the interfered cell is the same frequency interference, and determining the same frequency interference of which the time delay exceeds a set time delay threshold value as atmospheric waveguide interference;
s2, synchronizing with the interference signal interfered by the atmospheric waveguide to obtain a Physical Cell Identity (PCI) of an interference source cell generating the atmospheric waveguide interference, periodically monitoring a System Information Block (SIB) message of the interference source cell to obtain global identifier (ECGI) information of the interference source cell, and determining the position of the interference source cell according to the ECGI information;
s3, dividing the interfered cell into different area ranges by taking the interfered core site as a concentric circle according to the position relation of the interfered cell and the interference source cell, and respectively carrying out interference suppression on each area range;
the step S3 specifically includes:
calculating the difference OFDM symbol number X between the disturbed core station and the interference signal according to the time delay;
if X is less than or equal to 9, the special subframe ratio of the interfered cell and the interference source cell is jointly modified to 3:9: 2;
if X is more than 9, dividing the interfered cell into different area ranges by taking the interfered core site as a concentric circle, and performing interference suppression processing on the interfered base station and nearby base stations by using the divided area ranges;
in step S3, taking the interfered core sites as concentric circles, dividing the interfered cell into different area ranges specifically includes:
determining an interference area interfered by atmospheric waveguide caused by the same interference source cell, making a boundary ellipse according to the boundary of the interference area, enabling the long axis of the boundary ellipse to be parallel to the interference direction and the short axis to be perpendicular to the interference direction, and calculating the positions of two focuses of the boundary ellipse;
taking a focus far away from an interference source cell in the boundary ellipse as a common focus, and making an ellipse layer by layer from inside to outside in the boundary ellipse so as to divide an interference area into different area ranges; wherein, the number Y of the ellipses is X/9, and the Y is rounded up; the radius of the long axis of the nth ellipse from inside to outside in the boundary ellipse is n (a/Y), n is less than or equal to Y, and a is the radius of the long axis of the boundary ellipse.
2. The atmospheric waveguide interference suppression method according to claim 1, wherein the step S1 specifically includes:
monitoring the interference condition of a Physical Resource Block (PRB) of a cell, and if the intensity of an interference signal received by the cell exceeds a set interference threshold, judging the cell to be an interfered cell;
carrying out same frequency judgment on interference signals of the interfered cell, if the interference signals are the same frequency interference, obtaining the time delay of the same frequency interference, and carrying out time delay judgment on the interference signals to obtain the time delay required by the transmission of the interference signals of the same frequency interference to the interfered cell;
and if the time delay exceeds a set time delay threshold value, judging that the same frequency interference is atmospheric waveguide interference.
3. The atmospheric waveguide interference suppression method according to claim 2, wherein said obtaining a co-channel interference delay comprises:
obtaining interference sweep frequency data of an Orthogonal Frequency Division Multiplexing (OFDM) symbol level of an interfered cell, judging that the same frequency interference has no time delay if all OFDM symbols are interfered, and obtaining the time delay of the same frequency interference according to the last interfered OFDM symbol if not all OFDM symbols are interfered.
4. The atmospheric waveguide interference suppression method according to claim 1, wherein the step S3 further includes:
searching interference frequency band and frequency point information of an interference source cell, and carrying out frequency error on the interference source cell and an interfered cell; or
And adjusting the direction angle and the downward inclination angle of the electrically-adjusted antenna, and performing directional avoidance by combining the distance and the angle between the interfered cell and the interference source cell.
5. The atmospheric waveguide interference suppression method according to claim 1, wherein in step S3, the interference suppression processing on the interfered base station and the neighboring base station in the divided area ranges specifically includes:
adjusting the interfered cells in each layer of ellipse through frame header frequency offset deviation, and then delaying the time slot reference of the interfered cells to avoid atmospheric waveguide interference;
if the frame head adjustment amplitude of the interfered cell in the elliptical layer exceeds the GP protection interval of the cell outside the elliptical layer, the cell outside the elliptical layer adopts a radiation gradual change algorithm according to the number of the interval layers with the elliptical layer, and simultaneously performs frame head adjustment so as to enable the interfered cell in the elliptical layer and the cell outside the elliptical layer to be free from interference.
6. The atmospheric waveguide interference suppression method according to claim 5, wherein the cell outside the elliptical layer adopts a radiation gradual change algorithm according to the number of layers spaced from the elliptical layer, and performs frame header adjustment simultaneously, specifically comprising:
the frame head of the interfered cell in the oval layer in the boundary oval is adjusted from inside to outside, the frame head of the interfered cell in the oval layer at the innermost layer is moved backwards by 9 OFDM symbols, and in each two adjacent oval layers, the frame head of the interfered cell in the oval layer at the outer layer is moved backwards by 9 OFDM symbols based on the frame head of the interfered cell in the oval layer at the inner layer.
7. An atmospheric waveguide interference suppression system, comprising:
the atmospheric waveguide interference judgment module is used for obtaining the time delay of the same frequency interference after determining that the interference suffered by the interfered cell is the same frequency interference, and determining the same frequency interference of which the time delay exceeds a set time delay threshold value as the atmospheric waveguide interference;
an interference source cell determining module, configured to synchronize with an interference signal interfered by the atmospheric waveguide, to obtain a physical cell identity PCI of an interference source cell that generates the atmospheric waveguide interference, and periodically monitor a system information block SIB message of the interference source cell, to obtain an global identifier ECGI information of the interference source cell, and determine a location of the interference source cell according to the ECGI information;
the interference suppression module is used for dividing the interfered cell into different area ranges by taking the interfered core station as a concentric circle according to the position relation between the interfered cell and the interference source cell, and performing interference suppression on each area range respectively;
dividing the interfered cell into different area ranges by taking the interfered core station as a concentric circle according to the position relationship between the interfered cell and the interference source cell, and respectively performing interference suppression on each area range specifically comprises:
calculating the difference OFDM symbol number X between the disturbed core station and the interference signal according to the time delay;
if X is less than or equal to 9, the special subframe ratio of the interfered cell and the interference source cell is jointly modified to 3:9: 2;
if X is more than 9, dividing the interfered cell into different area ranges by taking the interfered core site as a concentric circle, and performing interference suppression processing on the interfered base station and nearby base stations by using the divided area ranges;
taking the interfered core sites as concentric circles, dividing the interfered cells into different area ranges, specifically comprising:
determining an interference area interfered by atmospheric waveguide caused by the same interference source cell, making a boundary ellipse according to the boundary of the interference area, enabling the long axis of the boundary ellipse to be parallel to the interference direction and the short axis to be perpendicular to the interference direction, and calculating the positions of two focuses of the boundary ellipse;
taking a focus far away from an interference source cell in the boundary ellipse as a common focus, and making an ellipse layer by layer from inside to outside in the boundary ellipse so as to divide an interference area into different area ranges; wherein, the number Y of the ellipses is X/9, and the Y is rounded up; the radius of the long axis of the nth ellipse from inside to outside in the boundary ellipse is n (a/Y), n is less than or equal to Y, and a is the radius of the long axis of the boundary ellipse.
8. The atmospheric waveguide interference suppression system according to claim 7, wherein the interference suppression module is further configured to retrieve interference frequency band and frequency point information of the interference source cell, and perform frequency error between the interference source cell and the interfered cell; or
And adjusting the direction angle and the downward inclination angle of the electrically-adjusted antenna, and performing directional avoidance by combining the distance and the angle between the interfered cell and the interference source cell.
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