Abstract:
The examples of the present invention disclose an anti-interference method and device in a common-frequency networking mobile communication system. The method includes: creating a candidate cell list according to probability that each adjacent cell of a current cell interferes with the current cell; selecting a selected cell list from the candidate cell list according to the probability; performing channel estimation for adjacent cells in the selected cell list, obtaining current signal power of each adjacent cell in the selected cell list according to a channel estimation result, and selecting a detected cell list from the selected cell list according to the signal power; and performing joint detection for adjacent cells in the detected cell list to eliminate interference of the adjacent cells in the detected cell list on the current cell.

Description:
FIELD OF THE INVENTION 
     The present invention relates to anti-interference technologies in a mobile communication system, and more particularly to an anti-interference method and device in a common-frequency networking mobile communication system. 
     BACKGROUND OF THE INVENTION 
     In a common-frequency networking mobile communication system, user signals of common-frequency adjacent cells interfere with user signals of a current cell, so as to decrease communication quality. 
     At present, a static common-frequency adjacent cell interference list is configured. The interference can be decreased through performing joint detection for cells in the common-frequency adjacent cell interference list, so as to improve communication quality. A specific method may refer to  FIG. 1 . 
       FIG. 1  is a flowchart illustrating a conventional method for decreasing interference of common-frequency adjacent cells. As shown in  FIG. 1 , the method includes the following steps. 
     Step  101 , a common-frequency adjacent cell interference list is configured in a device at network side of a current cell. 
     The common-frequency adjacent cell interference list may be configured through multiple configuration methods. For example, in a network layout phase, adjacent cells which cause stronger interfere on the current cell are selected from common-frequency adjacent cells according to the maximum user number supported by each adjacent cell, and the selected adjacent cells are added into the common-frequency adjacent cell interference list; or, a Radio Network Controller (RNC) determines user distribution of each cell covered by the RNC, analyzes the interference of each cell on adjacent cells according to the user distribution, selects adjacent cells which cause stronger interfere on the current cell from common-frequency adjacent cells, and adds the selected adjacent cells into the common-frequency adjacent cell interference list configured in the device at the network side of the current cell; or all adjacent cells of the current cell are added into the common-frequency adjacent cell interference list. 
     After the static common-frequency adjacent cell interference list is configured in step  101 , joint detection is performed for cells in the common-frequency adjacent cell interference list through steps  102  and  103 , so as to decrease the interference of common-frequency adjacent cells on the current cell. 
     Step  102 , in a mobile communication procedure, interference information of each adjacent cell in the common-frequency adjacent cell interference list is obtained through channel estimation. 
     In this step, interference code channel information of adjacent cells, i.e., the interference information of the adjacent cells, is obtained according to cell information in the configured common-frequency adjacent cell interference list and channel estimation information. 
     Step  103 , the interference of each adjacent cell on the current cell is eliminated according to the interference information. 
     As can be seen from the above solution, the common-frequency adjacent cell interference list in the conventional method is a pre-configured static list. However, since the actual interference of each adjacent cell on the current cell changes dynamically, at some time, the static list may not include adjacent cells which cause stronger interference on the current cell. 
     Since anti-interference processing is performed only for the adjacent cells in the static list, if the adjacent cells which cause stronger interfere on the current cell are not added into the static list, the anti-interference performance of the current cell will be decreased, so as to decrease communication quality. 
     Every time the interference of an adjacent cell on the current cell is eliminated, channel estimation needs to be performed, and thus excessive configuration of the static list will result in the complexity of the device for performing anti-interference processing at the network side, so as to increase device costs. 
     SUMMARY OF THE INVENTION 
     In view of the above, the object of examples of the present invention is to provide an anti-interference method and device in a common-frequency networking mobile communication system, by which the ability that each cell in the mobile communication system decreases the interference of common-frequency adjacent cells can be enhanced, communication quality can be improved, and the complexity of a device for performing anti-interference processing at the network side can be decreased. 
     In order to achieve the above object, the technical solution provided by the examples of the present invention is implemented as follows. 
     An anti-interference method in a common-frequency networking mobile communication system includes: 
     An anti-interference device in a common-frequency networking mobile communication system includes: 
     As can be seen from the above technical solution, a candidate cell list is created according to the probability that each adjacent cell of the current cell interferes with the current cell, a selected cell list is selected from the candidate cell list according to the probability, channel estimation is performed for adjacent cells in the selected cell list, the current signal power of each adjacent cell in the selected cell list is obtained according to the channel estimation result, a detected cell list is selected from the selected cell list according to the signal power, and joint detection is performed for adjacent cells in the detected cell list to eliminate the interference of the adjacent cells on the current cell. 
     The detected cell list is created dynamically according to the probability that each adjacent cell interferes with the current cell and the current signal power of the adjacent cells, and usually contains adjacent cells which cause stronger interference on the current cell. Therefore, the present invention can select the adjacent cells which cause stronger interference on the current cell to perform anti-interference processing, so as to enhance the ability that each cell in the mobile communication system decreases the interference of common-frequency adjacent cells, and improve communication quality. In addition, since the number of adjacent cells in the detected cell list is small, the complexity of the device for performing anti-interference processing at the network side is decreased. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a flowchart illustrating a conventional method for decreasing interference of common-frequency adjacent cells. 
         FIG. 2  is a flowchart illustrating a method for decreasing interference of common-frequency adjacent cells according to an example of the present invention. 
         FIG. 3  is a schematic diagram illustrating the structure of a device for decreasing interference of common-frequency adjacent cells according to an example of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In order to make the object, technical solution and merits of the present invention clearer, the present invention will be illustrated hereinafter in detail with reference to the accompanying drawings and examples. 
       FIG. 2  is a flowchart illustrating a method for decreasing interference of common-frequency adjacent cells according to an example of the present invention. As shown in  FIG. 2 , the method includes the following steps. 
     Step  201 , a candidate cell list is created according to probability that each adjacent cell of a current cell interferes with the current cell. 
     In this step, IDs of adjacent cells to be added into the candidate cell list and initial probability that each adjacent cell interferes with the current cell may be determined in the network layout phase according to such factors as user number which can be supported by each adjacent cell, transmission power of each adjacent cell, physical location relation between each adjacent cell and the current cell, and an antenna direction pattern of each adjacent cell. And then, the candidate cell list and the probability are stored in a device for performing anti-interference processing at the network side. Usually, the device at the network side is a base station. 
     Generally, the nearer the distance between an adjacent cell and the current cell is, the stronger the interference of the adjacent cell on the current cell is. When the antenna direction pattern of the adjacent cell points to the current cell, the interference of the adjacent cell on the current cell is stronger. And thus, when other factors of multiple adjacent cells, such as the supported user number and the transmission power, are the same, an adjacent cell which is nearer to the current cell and of which the antenna direction pattern points to the current cell may be added into the front location in the candidate cell list. In this way, the location of each adjacent cell in the candidate cell list can indicate the probability that each adjacent cell interferes with the current cell. 
     In this step, an initial cell list for storing the IDs of all adjacent cells of the current cell may be stored in the device at the network side in advance. The device at the network side also stores initial probability that each adjacent cell in the initial cell list interferes with the current cell. The candidate cell list is selected from the initial cell list according to the probability that each adjacent cell in the initial cell list interferes with the current cell. 
     The method of determining the initial probability that each adjacent cell in the initial cell list interferes with the current cell is the same as that of determining the initial probability that each adjacent cell in the candidate cell list interferes with the current cell. 
     The probability that each adjacent cell in the initial cell list interferes with the current cell may be updated periodically. 
     A probability update period T 3  of adjacent cells in the initial cell list is preset. When T 3  expires, channel estimation is performed for the adjacent cells in the initial cell list, the current signal power of each adjacent cell in the initial cell list is obtained according to a channel estimation result, and the probability of the adjacent cells in the initial cell list is updated according to the signal power. 
     In order to increase the probability update speed, a following method for updating the probability of adjacent cells in the initial cell list may be used. When T 3  expires, only the probability of residual adjacent cells in the initial cell list except adjacent cells in the candidate cell list is updated. Specifically, channel estimation is performed for the residual adjacent cells, the current signal power of the residual adjacent cells is obtained according to a channel estimation result, and the probability of the residual adjacent cells is updated according to the signal power. 
     Correspondingly, the candidate cell list may also be updated periodically. When the candidate cell list is updated, an adjacent cell of which probability is smaller in the candidate cell list is replaced with an adjacent cell of which probability is larger in the initial cell list, or an adjacent cell is randomly selected from the adjacent cells in the initial cell list which are not in the candidate cell list currently, and the selected adjacent cell is added into the candidate cell list. 
     A longer T 3  and a longer update period of the candidate cell list may be set, e.g., T 3  and the update period are set as one week. 
     Step  202 , a selected cell list is selected from the candidate cell list according to the probability. 
     Step  203 , a detected cell list is selected from the selected cell list. 
     In this step, channel estimation is performed for adjacent cells in the selected cell list, the current signal power of each adjacent cell in the selected cell list is obtained according to a channel estimation result, and the detected cell list is selected from the selected cell list according to the signal power. 
     Step  204 , joint detection is performed for adjacent cells in the detected cell list to estimate the interference of the adjacent cells in the detected cell list on the current cell. 
     In steps  202  and  203 , the probability of each adjacent cell in the candidate cell list may be updated periodically, and the selected cell list may also be updated periodically according to the most recent probability of each adjacent cell in the candidate cell list. 
     Specifically, a probability update period T 1  of adjacent cells in the candidate cell list and a cell update period T 2  of the selected cell list are preset, where T 2 ≧T 1 . 
     When T 1  expires, the probability of the adjacent cells in the detected cell list is increased by a first probability update value P 1 , the probability of adjacent cells which are in the selected cell list and are not in the detected cell list subtracted by a second probability update value P 2 , and the probability of adjacent cells which are in the candidate cell list and are not in the selected cell list is increased by a third probability update value Δ. 
     When T 2  expires, a new selected cell list is reselected from the candidate cell list according to the updated probability of the adjacent cells in the candidate cell list. 
     For example, adjacent cells may be selected according to a sequence of the updated probability of the adjacent cells in the candidate cell list from big to small, and the adjacent cells in the selected cell list are all replaced with the adjacent cells selected from the candidate cell list. Or, adjacent cells are selected according to a sequence of the updated probability of the adjacent cells in the candidate cell list from big to small, and a part of the adjacent cells in the selected cell list are replaced with the adjacent cells selected from the candidate cell list, where the number of the replaced adjacent cells is not larger than a preset value. The preset value may be configured according to the requirements on the complexity of the device at the network side. Generally, the lower the complexity of the device at the network side is, the smaller the preset value is. 
     When the new selected cell list is reselected from the candidate cell list according to the updated probability of the adjacent cells in the candidate cell list, if the probability which is obtained by performing probability update for the adjacent cells in the candidate cell list when T 3  expires is different from the probability which is obtained by performing probability update for the adjacent cells in the candidate cell list when T 1  expires, a new selected cell list is reselected from the candidate cell list according to the probability which is obtained by performing probability update for the adjacent cells in the candidate cell list when T 1  expires. That is to say, when being selected from the candidate cell list, the selected cell list is selected according to the probability obtained by performing probability update for the adjacent cells in the candidate cell list. Specifically, a probability table is respectively maintained for the candidate cell list and the initial cell list, and the selected cell list is selected according to the probability table of the candidate cell list. 
     When the selected cell list is selected from the candidate cell list according to the probability, if the updated probability of multiple adjacent cells in the candidate cell list is the same, it is determined, according to the probability, the physical location relation between the multiple adjacent cells and the current cell, and respective antenna direction patterns of the multiple adjacent cells, whether to add the multiple adjacent cells into the selected cell list. For example, if the number of updated adjacent cells is limited so that only one adjacent cell in the multiple adjacent cells can be added into the selected cell list, an adjacent cell which is arranged in the front location of the candidate cell list according to the physical location relation between the multiple adjacent cells and the current cell and the antenna direction patterns of the multiple adjacent cells is added into the selected cell list. 
     According to the above method examples, a device for decreasing interference of common-frequency adjacent cells provided by an example of the present invention will be illustrated hereinafter. 
       FIG. 3  is a schematic diagram illustrating the structure of a device for decreasing interference of common-frequency adjacent cells according to an example of the present invention. As shown in  FIG. 3 , the device includes a candidate cell list maintaining module  301 , a selected cell list maintaining module  302 , a detected cell list maintaining module  303  and an anti-interference module  304 . 
     The candidate cell list maintaining module  301  is configured to store a candidate cell list which is created according to probability that each adjacent cell of a current cell interferes with the current cell, and probability that each adjacent cell in the candidate cell list interferes with the current cell. 
     The selected cell list maintaining module  302  is configured to select a selected cell list from the candidate cell list according to the probability that each adjacent cell in the candidate cell list interferes with the current cell and store the selected cell list. 
     The detected cell list maintaining module  303  is configured to perform channel estimation for adjacent cells in the selected cell list, obtain current signal power of each adjacent cell in the selected cell list according to a channel estimation result, and select a detected cell list from the selected cell list according to the signal power and store the detected cell list. 
     The anti-interference module  304  is configured to perform joint detection for adjacent cells in the detected cell list to eliminate interference of the adjacent cells in the detected cell list on the current cell. 
     The device further includes a probability update module. 
     The probability update module is configured to, when a preset probability update period T 1  expires, increase probability of the adjacent cells in the detected cell list by a first probability update value P 1 , subtract probability of adjacent cells which are in the selected cell list and are not in the detected cell list by a second probability update value P 2 , and increase probability of adjacent cells which are in the candidate cell list and are not in the selected cell list by a third probability update value Δ. 
     The selected cell list maintaining module  302  further includes a module configured to, when a cell update period T 2  expires, reselect a new selected cell list from the candidate cell list according to the updated probability of the adjacent cells in the candidate cell list, where T 2 ≧T 1 . 
     The procedure that the selected cell list maintaining module  302  selects the new selected cell list from the candidate cell list is as follows: 
     adjacent cells are selected according to a sequence of the updated probability of the adjacent cells in the candidate cell list from big to small, and all or part of the adjacent cells in the selected cell list are replaced with the adjacent cells selected from the candidate cell list. 
     The device may further include an initial cell list maintaining module. 
     The initial cell list maintaining module is configured to store an initial cell list containing IDs of all adjacent cells of the current cell, and store probability that each adjacent cell in the initial cell list interferes with the current cell. 
     The candidate cell list maintaining module  301  further includes a module configured to select the candidate cell list from the initial cell list according to the probability that each adjacent cell in the initial cell list interferes with the current cell. 
     The candidate cell list maintaining module  301  may further include a module configured to, when a probability update period T 3  of the adjacent cells in the initial cell list expires, perform channel estimation for residual adjacent cells in the initial cell list except the adjacent cells in the candidate cell list, obtain current signal power of the residual adjacent cells according to a channel estimation result, and update the probability of the residual adjacent cells according to the signal power. 
     The candidate cell list maintaining module  301  may further include a module configured to, when the candidate cell list is updated, select an adjacent cell from adjacent cells which are in the initial cell list and are not in the candidate cell list currently, and add the selected adjacent cell into the candidate cell list. The candidate cell list maintaining module  301  may randomly select an adjacent cell from the adjacent cells which are in the initial cell list and are not in the candidate cell list currently and add the selected adjacent cell into the candidate cell list, or select an adjacent cell according to a preset rule and add the selected adjacent cell into the candidate cell list, e.g., select an adjacent cell according to the physical location of the adjacent cell, an antenna direction pattern of the adjacent cell and/or the probability that the adjacent cell interferes with the current cell, and add the selected adjacent cell into the candidate cell list. 
     The selected cell list maintaining module  302  may further include a module configured to, if probability of multiple adjacent cells in the candidate cell list is the same, determine, according to the probability of the multiple adjacent cells, the physical location relation between the multiple adjacent cells and the current cell, and respective antenna direction patterns of the multiple adjacent cells, whether to add the multiple adjacent cells into the selected cell list. 
     The foregoing is only the preferred examples of the present invention and is not used to limit the protection scope of the present invention. Any modification, equivalent substitution and improvement without departing from the spirit and principle of the present invention are within the protection scope of the present invention.