CN100407600C - Method for configuring cell codeword resources in time division synchronous code division multiple access system networking - Google Patents

Abstract

The present invention relates to a method for allocating cell code word resources in a TD-SCDMA system. SYNC-DL code characteristics are firstly utilized to program code words for the first time on the basis of analyzing the cross correlation of code words in TD-SCDMA system cold groups. After coincident codes of band spread scrambling codes are eliminated, scrambling code characteristics are utilized to program the code words for the second time. After cell code words are multiplexed, a honeycombed code word allocation plan is obtained. The method of the present invention utilizes different cross correlation characteristics among code words to allocate code word resources, so that interference in UE cell search can be reduced, UE can be accessed rightly, and simultaneously, interference among adjacent cells can also be reduced when users are in a connecting state.

Description

Method for configuring cell codeword resources in time division synchronous code division multiple access system networking

technical field

The present invention relates to a method for configuring cell codeword resources in a Code Division Multiple Access (CDMA) system network, in particular to a Time Division-Sync Code Division Multiple Access (Time Division-Sync Code) in the field of mobile communications Division Multiple Access) (hereinafter referred to as TD-SCDMA) system cell code resource configuration method. The present invention is applicable to the TD-SCDMA system in the field of mobile communication, and is also applicable to all CDMA systems in the field of mobile communication, especially Time Division Duplex Code Division Multiple Access (Time Division Duplex mode of CDMA) (abbreviated as TDD-CDMA) system and all Synchronous Code Division Multiple Access (Sync Code Division Multiple Access) (referred to as SCDMA) system.

Background technique

In all existing mobile communication systems, one or more of Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA) or CDMA characteristics of wireless resources are usually used. A combination of multiple access systems can be used to provide services for a large number of mobile users. For the third generation (3G) mobile communication system with CDMA as the main feature, each cell is usually configured with a certain uplink synchronization (SYNC-Uplink) (hereinafter referred to as SYNC-UL) code, Cell code words such as downlink synchronization (SYNC-Downlink) (hereinafter referred to as SYNC-DL) code and scrambling code. The codeword resources occupied by different cells are different, and the codeword resources are limited, which greatly limits the frequency band utilization of the system and limits the user capacity within a unit frequency band. But at the same time, it can also be seen that any method that can introduce the independent characteristics of wireless resources will improve the frequency band utilization. For example, the TD-SCDMA system uses FDMA/TDMA/CDMA to allocate resources, which is conducive to improving the frequency band utilization.

The capacity advantage of the CDMA system is mainly reflected in the wireless environment of many cells. Early mobile communication systems used a high-power base station to cover a large area, and the system bandwidth was severely limited, which could not meet the needs of mobile services. In a cellular system, a high-power base station transmitter is replaced by many low-power transmitters, and each low-power transmitter covers a cellular cell. In the CDMA cellular system, the codewords configured by the cells at a certain distance can be reused, which will greatly increase the system capacity and improve the frequency band utilization.

Since the data received by the receiving end contains not only the code group data of the own cell, but also the code group data of other cells, this introduces interference between neighboring cells, and the interference between different code groups is different, so it is necessary to study the code group In order to obtain a better code group configuration method to minimize the code group interference between cells. How to optimally configure cell codeword resources in a CDMA cellular system will be a good way for us to solve the shortage of codeword resources and improve system capacity.

Contents of the invention

In view of the foregoing, the purpose of the present invention is to combine the codeword characteristics of the TD-SCDMA system to propose a configuration method for cell codewords in the TD-SCDMA system networking, to solve the configuration problem of codewords, thereby reducing user equipment (User Equipment) ) (hereinafter referred to as UE) cell search interference, so that the UE can access correctly, and can also reduce the interference between neighboring cells when the user is connected. The codeword configuration of other systems can also be performed with reference to the present invention.

In order to achieve the above object, the configuration method of cell codeword resources in the TD-SCDMA system network of the present invention is mainly based on the analysis of the cross-correlation characteristics of the codewords in the TD-SCDMA system code group, first using SYNC-DL Code characteristics for the first codeword planning, after removing the repeated code of the spread spectrum scrambling code, and then use the scrambling code characteristics to carry out the second codeword planning, after the cell codeword multiplexing, if the number of cells in the multiplexing cluster is 3, 4, 7, 12, 13, 19, etc., to obtain a code word configuration diagram of a cellular structure. Since the method of the present invention uses the different cross-correlation characteristics between codewords to configure codeword resources, it can reduce the interference when the UE cell searches, so that the UE can access correctly, and can also reduce the interference between neighboring cells when the user is connected .

The configuration method of cell code word resource in the TD-SCDMA system networking of the present invention comprises the following steps:

Step S1: Use the characteristics of the SYNC-DL code to plan the code word for the first time, and determine the code group number where the code word of the cell is located;

Step S2: According to the required cell multiplexing mode 1×K, according to the results obtained in the above step S1, generate a cell structure diagram for multiplexing, wherein the code group number of each cell in the cell structure diagram of the cell is fixed Generated, and corresponds to the SYNC-DL code number; wherein the above K is the number of multiplexed cells, and K is greater than 1;

Step S3: Search for repeated codes of spread spectrum scrambling codes;

Step S4: Remove the scrambling code pairs with repeated codes from the 4×K scrambling codes, and use the characteristics of the scrambling codes to perform secondary codeword planning to determine the cell codeword number;

Step S5: Generate a cell structure diagram of codeword multiplexing.

Wherein, the above step S1 includes the following steps:

Step S11: Calculate the cross-correlation characteristics of the i-th group of SYNC-DL codes and other groups, find out the mean value of the cross-correlation characteristics, and form a 1×31 array, wherein the above i=1, 2, ... 32;

Step S12: Calculate the cross-correlation characteristics of the remaining 31 groups of SYNC-DL codes and other groups according to the above step S11;

Step S13: Find out the downlink synchronization code number corresponding to the minimum value of the mean value of the cross-correlation characteristic of the current SYNC-DL code group, and set the corresponding cross-correlation characteristic threshold to search for the minimum set, and find the current SYNC-DL that satisfies the conditions The downlink synchronization code with the smallest code cross-correlation characteristic generates a minimum set;

Step S14: Configure codewords for cells layer by layer. First, find out the downlink synchronization code with the most occurrences in the "quasi-intersection" of the minimum set of all codewords and use it as the first-layer central cell, where the above-mentioned "quasi-intersection" It is a set composed of the same downlink synchronization code numbers appearing in the minimum set of different downlink synchronization codes;

Step S15: Take each of the six cells around the center cell on the first layer as the center, and these six cells are called the center cell on the second layer, and then select from the respective minimum sets of the six center cells on the second layer Configuration, and the central cell number of the first layer cannot appear, and the reappearance of the used central cell number is called repetition;

S16: Repeat step S14 for the above-mentioned second layer central cell, and the selected central cell number cannot appear.

In addition, different cross-correlation characteristic thresholds are set in the above step S13, and different minimum sets will be obtained. Then, the first codeword planning is performed using the SYNC-DL code characteristics. The code group numbers of the planned cell codewords are different, and finally The cell code word configuration groups of the cellular structure are also different.

The cell multiplexing modes in the above step S2 are, for example, 1×3, 1×4, 1×7, 1×12, 1×13 and 1×19.

Wherein, above-mentioned step S3 comprises the following steps:

S31: Multiply the 128 scrambling codes with all the spreading codes;

S32: Compare the spreading scrambling codes obtained by the above multiplication in pairs, and record the scrambling code pair numbers corresponding to the same spreading scrambling codes.

The above-mentioned spreading codes are different pluralized spreading codes, wherein the spreading factor corresponding to the spreading code is Q, and Q includes 1, 2, 4, 8, 16, a total of 31 spreading codes, and the spreading factor is less than The spreading code of 16 needs to be extended in length, and the extended length is uniformly 16, and the weighting factors multiplied by different spreading codes are different when they are pluralized, and 24 of the spreading codes after pluralizing are different;

Wherein, above-mentioned step S4 comprises the following steps:

S41: Select all scrambling codes corresponding to the downlink synchronization code numbers in the cellular structure diagram of the cell generated by the above step S2, a total of 4×K;

S42: From the 4×K scrambling codes obtained in the above step S41, remove the scrambling code group corresponding to the same spreading scrambling code obtained in the above step S32;

S43: Calculate pairwise cross-correlation characteristics of the remaining scrambling codes in the above step S42;

S44: Selecting a scrambling code number with a small cross-correlation property as the cell code of each cell.

In this way, each cell occupies a codeword configuration group (a, b), where a represents the result of the SYNC-DL codeword planning performed by the above step S1—that is, the code group number where the codeword of the cell is located, and b represents the number of the codeword configured by The result of the scrambling code planning performed in the above step S4—that is, the codeword number corresponding to the code group number where the cell codeword is located.

After using the SYNC-DL code to determine the group number, since there are 8 SYNC-UL codes in each code group, and these 8 SYNC-DL codes are all used in a cell, no additional planning is required.

After the code word number in the code group is determined with the scrambling code, since the basic training sequence code (hereinafter referred to as the basic Midamble code) number used by each sub-district is in one-to-one correspondence with the scrambling code number, after the code group number is determined, When the codeword number is determined by the cross-correlation characteristic of the scrambling code, the method of selecting the codeword number by using the cross-correlation characteristic of the scrambling code is also applicable to determining the codeword number by using the cross-correlation characteristic of the basic Midamble code.

The present invention optimizes the configuration of codeword resources, uses two codeword planning, adopts the cellular structure mode, and obtains the codeword configuration method used by each adjacent cell in the system, and this method reduces the interference when the UE cell searches , enabling the UE to access correctly, reducing interference in the system, improving frequency band utilization, and saving frequency resources.

The specific implementation of the method of the present invention will be further described in detail with preferred embodiments below in conjunction with the accompanying drawings. The above and other objects, features and advantages of the present invention will be apparent to those skilled in the art from the detailed description of the method of the present invention.

Description of drawings

Fig. 1 is to adopt the flow chart of code word planning method of the present invention;

Figure 2 is a cellular structure diagram of 12 cells obtained after SYNC-DL code planning;

Fig. 3 is a cellular structure diagram of 12 cells obtained after scrambling code planning;

Fig. 4 is a diagram of a cellular structure in a 12-cell multiplexing mode.

Detailed ways

Taking the 1×12 cell multiplexing mode as an example, the implementation of the technical solution of the present invention will be further described in conjunction with the drawings and specific embodiments.

In the TD-SCDMA system, different cells have different code group configurations. The cell code group configuration refers to the unique code groups of the cell. Different adjacent cells will be configured with different code groups. In the TD-SCDMA system, a total of 32 SYNC-DL codes are defined. Although the SYNC-DL codes have been optimized and screened when selecting the SYNC-DL codes, the pairwise correlation characteristics in the set of 1 to 32 SYNC-DL codes will still be different. has a difference. When the UE is located at the junction of the downlink pilot signal coverage of two base stations, and the distance between the UE and the two base stations is nearly equal and the shadow fading cross-correlation characteristics are strong, then the downlink pilot levels of the above base stations have the same power. If the downlink pilot codes of two base stations have strong cross-correlation characteristics, it will make it more difficult for the UE to search for a cell. This is because the stronger the cross-correlation characteristics of the downlink pilot codes, the greater the mutual interference. The lower the signal-to-noise ratio of the signal will affect the output and judgment of the SYNC-DL code matched filter.

In order to overcome this problem as much as possible, when configuring the SYNC-DL codes of adjacent cells, the cross-correlation characteristics between different SYNC-DL codes should be considered to make their cross-correlation characteristics as weak as possible, which will benefit the UE Cell search reduces interference during UE access.

There is only one SYNC-DL code in a code group. As long as the SYNC-DL code used by the cell is determined, which SYNC-UL code, basic Midamble code and scrambling code (that is, the cell code) is known. In addition, the scrambling code needs to be further configured. The scrambling code of the TD-SCDMA system is unique to each cell, and its main purpose is to overcome the interference from adjacent cells, whiten the interference signals of adjacent cells, make the baseband power spectrum basically consistent, and reduce the signal peak-to-average ratio. Since the scrambling code is used to identify the cell, only one scrambling code sequence is configured for each cell. In the TD-SCDMA system, a total of 128 scrambling codes are defined and divided into 32 groups, each code group has 4 scrambling codes, and the scrambling codes with small cross-correlation characteristics are preferentially selected as the cells used by adjacent cells Code, that is, scrambling code.

Since the lengths of spreading codes and scrambling codes of inter-cell users are both 16, they perform a dot product to generate 16 long spreading scrambling codes. Since all 128 scrambling codes may be used, if a certain scrambling code is used If selected, it will be multiplied by all spreading codes used in the cell, so that different scrambling codes multiplied by different spreading codes may generate the same spreading scrambling code, we call such codewords repeated codes , if such a codeword is used by an adjacent cell, then such two users will have strong interference with each other, and user data cannot be correctly demodulated. Therefore, when configuring codewords, not only the influence of the cross-correlation characteristics of SYNC-DL codes on UE cell search must be considered, but also whether there are code pairs with repeated codes or strong cross-correlation characteristics between different spreading scrambling code groups, and These codewords are not allocated to adjacent cells/sectors with overlapping coverage. Therefore, the repeated code should be removed before configuring the scrambling code.

In the CDMA cellular system, the code words configured by the cell can be reused, which will greatly increase the system capacity and improve the frequency band utilization. As long as the distance between two cells is large enough, they can use the same codeword without causing obvious mutual interference. The present invention adopts the cellular structure of codeword multiplexing to realize the codeword networking in the TD-SCDMA system.

When different cross-correlation characteristic thresholds are selected in the cell code word configuration method in the TD-SCDMA system network of the present invention, different cell multiplexing mode code word configuration scheme results will be obtained.

According to the flow chart of codeword planning shown in Figure 1, and according to codeword characteristic analysis and computer simulation, a 1 × 12 cell multiplexing mode codeword configuration method and results are as follows:

First, use the characteristics of the SYNC-DL code to plan the first code word, and determine the code group number where the code word of the cell is located, mainly including the following steps:

1) Calculate the cross-correlation characteristics of the i-th group of SYNC-DL codes and other groups, find out the mean value of the cross-correlation characteristics, and form a 1 * 31 array, wherein i=1, 2, ... 32;

2) Select the current SYNC-DL code i and the jth SYNC-DL code with the smallest average value of cross-correlation characteristics, and set the appropriate cross-correlation characteristic threshold to search for the minimum set to find the cross-correlation with the current codeword that satisfies the conditions The codeword with the smallest characteristic generates a minimal set;

3) carry out codeword allocation to the sub-district layer by layer, at first, find out the codeword with the greatest number of occurrences in the "quasi-intersection" of the minimum set of all codewords and use it as the first layer central cell;

4) Select and configure the minimum concentration of the six cells around the center cell of the first layer above with each as the center (referred to as the center cell of the second layer), and no central cell number of the first layer can appear. The reappearance of the past central cell number is called repetition;

5) Step 4 is repeated for the second-floor central cell, and the selected central cell number cannot appear;

It is executed sequentially until the codewords of 12 cells are selected.

According to the cross-correlation characteristics of 32 groups of SYNC-DL codes, 12 groups of SYNC-DL codes are selected to generate the cellular structure diagram of 12 cells, as shown in Figure 2. The selected 12 sets of SYNC-DL code numbers are: 6, 7, 8, 11, 13, 18, 19, 21, 28, 29, 31, 32.

Then, search for the repeated codes of 48×24=1152 spread spectrum scrambling codes corresponding to 4×12=48 scrambling codes in these 12 groups, record the codeword numbers of the scrambling code pairs with repeated codes, and share them with other scrambling codes in the networking The scrambling code pairs with repeated codes cannot be configured in the network. After removing these codewords, the second codeword planning is carried out according to the cross-correlation characteristics of the scrambling codes, and the scrambling code numbers with small cross-correlation characteristics are selected as the cell codes of each cell. , that is, the scrambling code. As shown in Figure 3, the codeword configurations of the 12 cells obtained after scrambling code planning are (29, 4), (11, 4), (32, 3), (21, 2), (28, 3), (6, 3), (13, 4), (19, 2), (7, 4), (8, 1), (18, 1), (31, 1), configure the group with the codeword in the figure ( 29, 4) as an example, the code word configuration group (29, 4) represents the fourth code word of the 29th code group, and the others are similar.

Finally, the cellular structure diagram of the 12 cells is multiplexed to obtain the multiplexed cellular structure diagram of the cell network, as shown in FIG. 4 .

In this way, the configuration of cell code resources in the TD-SCDMA system network is completed, and the SYNC-DL code, SYNC-UL code, basic Midamble code and scrambling code used by each cell in the network are all determined. Among them, there are eight SYNC-UL codes, and one SYNC-DL code, basic Midamble code, and scrambling code.

The working principle of the present invention has been described in detail above, but this is only a vivid example for easy understanding, and should not be regarded as limiting the scope of the present invention. Similarly, any ordinary person in the technical field can design a corresponding channel estimation device and make various possible equivalent changes or replacements according to the technical solution of the present invention and the description of its preferred embodiments, but all these changes Or replacement should belong to the protection scope of the claims of the present invention.

Claims (9)

1. the collocation method of sub-district code source in the TDS-CDMA system networking is characterized in that comprising the steps:

Step S1: utilize the descending synchronous code characteristic to carry out the code word planning first time, determine the block number at district code word place;

Step S2: according to required cell reuse pattern 1 * K, the result who obtains according to above-mentioned steps S1 generates in order to multiplexing cell cellular structure chart, and wherein the block number of each sub-district is fixing in this cell cellular structure chart generates, and corresponding descending synchronous code number; Wherein above-mentioned K is multiplexing sub-district number, and K is greater than 1;

Step S3: the repeated code to the spread spectrum scrambler is searched for;

Step S4: removing in 4 * K scrambler has the scrambler of repeated code right, and utilizes the scrambler characteristic to carry out the planning of secondary code word, determines the cell code font size;

Step S5: the cell cellular structure chart that generated codeword is multiplexing.

2. collocation method according to claim 1 is characterized in that above-mentioned steps S 1 comprises the steps:

Step S11: calculate the their cross correlation of i group descending synchronous code and other groups, find out the average of their cross correlation, form one 1 * 31 array, wherein above-mentioned i=1,2 ... 32;

Step S12: according to above-mentioned steps S11 remaining 31 groups of descending synchronous code is done their cross correlation with other groups respectively and calculate;

Step S13: find out and the pairing descending synchronous code of minimum value of the average of current descending synchronous code their cross correlation number, and corresponding their cross correlation thresholding is set carries out minimal set search, searching that satisfy condition with descending synchronous code current descending synchronous code their cross correlation minimum, generate a minimal set;

Step S14: successively the code word configuration is carried out in the sub-district, at first find out occurrence number is maximum in " accurate occur simultaneously " of minimal set of all code words descending synchronous code and with it as the ground floor center cell, wherein above-mentioned " the accurate common factor " is the set that the identical descending synchronous code that occurs in the minimal set of different descending synchronous codes number is formed;

Step S15: to six sub-districts around the above-mentioned ground floor center cell again with the center of respectively doing for oneself, these six sub-districts are called as second layer center cell, in these six second layer center cell minimal set separately, select configuration again, and the center cell number that ground floor can not occur, the center cell of wherein having used number repetition appears being called as once more;

S16: above-mentioned second layer center cell is repeated above-mentioned steps S14, the center cell that can not occur having selected for use number.

3. collocation method according to claim 2, it is characterized in that in above-mentioned steps S13, being provided with different their cross correlation thresholdings, different minimal sets will be obtained, then utilize the descending synchronous code characteristic to carry out the code word planning first time, the block number difference at the district code word place of planning, the honeycomb district code word configuration group that finally obtains are also different.

4. collocation method according to claim 1 is characterized in that the cell reuse pattern among the above-mentioned steps S2 comprises 1 * 3,1 * 4,1 * 7,1 * 12,1 * 13 or 1 * 19.

5. collocation method according to claim 1 is characterized in that above-mentioned steps S3 comprises the steps:

S31: 128 scramblers are multiplied each other with all spreading codes respectively;

S32: the above-mentioned spread spectrum scrambler that obtains that multiplies each other is compared in twos, and the pairing scrambler of record same spread scrambler is checked the number.

6. collocation method according to claim 5 is characterized in that above-mentioned spreading code is the spreading code of plural numberization inequality.

7. according to claim 5 or 6 described collocation methods, it is characterized in that comprising the steps: at above-mentioned steps S4

S41: select descending synchronous code number pairing all scramblers in the cell cellular structure chart that generates by above-mentioned steps S2, have 4 * K;

S42: from 4 * K the scrambler that above-mentioned steps S41 obtains, the pairing scrambler group of same spread scrambler that above-mentioned steps S32 obtains is got rid of;

S43: the their cross correlation in twos that calculates residue scrambler among the above-mentioned steps S42;

S44: select the little scrambler of their cross correlation number subzone code as each sub-district.

8. collocation method according to claim 1 is characterized in that 8 uplink synchronous codes are arranged in each code character, and these 8 uplink synchronous codes are all used in a sub-district, does not need to add in addition planning.

9. collocation method according to claim 1, it is characterized in that employed basic Midamble sign indicating number in each sub-district number and scrambler number are one to one, after determining block number, carry out a yard font size when determining with the their cross correlation of scrambler, scrambler is done their cross correlation carry out method that yard font size chooses and be equally applicable to that basic Midamble sign indicating number is done their cross correlation and determine a sign indicating number font size.

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