KR100314218B1 - Method for pursuiting synchronous of pseudo noise code in a mobile communication cell site of code division multiple access - Google Patents

Abstract

In the CDMA mobile communication base station system according to the present invention, in the PN code synchronization tracking method, when the DSP passes the search section and the integration section as parameters to the ATM, the ATM returns the energy values for all paths using a match filter. When the calculated energy value is passed back to the DSP, the DSP extracts at least four or more values greater than the threshold value among these energy values and passes them to the demodulator to optimize the optimum between the mobile station and the base station demodulator. Is to search the path.

Description

Method for pursuiting synchronous of pseudo noise code in a mobile communication cell site of code division multiple access}

The present invention relates to a Pseudo Noise Code (PN code) synchronous tracking method in a Code Division Multiple Access (CDMA) mobile communication base station system. In particular, a DSP (Digital Signsal Processor) The present invention relates to a PN code synchronization tracking method in a CDMA mobile communication base station system by synchronizing a PN code between a terminal and a base station so that the base station can track the movement of the terminal station to perform demodulation of the best path.

In a conventional CDMA system, a modem board is constructed using INTEL 80960 as a CPU (Central Processing Unit) and a CSM (Cell Cite Modem) chip from Qualcomm, a modem chip. Tracking function is included.

This method has a Code Acquisition Part and a Code Tracking Loop in the CSM chip, and demodulates the data by obtaining the Channel Estimation value for the path while maintaining synchronization with the assigned path. It was the way. In other words, the channel estimation value is calculated for only one path in hardware using a code tracking loop.

Since this method uses channel estimation value for one path and uses it for synchronization tracking, it excludes the high quality channel estimation value that can come in through another path and only needs to perform synchronization tracking for only one path. And because of estimating a path in a hardware way, it causes inflexibility.

Accordingly, an object of the present invention is to solve the above-described problems according to the prior art, and an object of the present invention is to move a terminal station from a base station by synchronizing a PN code between a terminal and a base station using a DSP (Digital Signsal Processor). The present invention provides a PN code synchronization tracking device in a CDMA mobile communication base station system capable of performing a demodulation of a best path by tracking the s.

Another object of the present invention is to provide a PN code synchronization tracking method in a CDMA mobile communication base station system corresponding to the operation of the synchronization tracking device.

In other words, in the present invention, the modem board is configured by using DSP and ATM in the method of searching PN codes only for one path which is initially searched by hardware, and the DSP controls the ATM value. . In other words, ATM calculates energy values for all paths and reports the results to the DSP. By controlling this, DSP obtains channel estimation results and energy values for all paths and continuously changes the information on the best path. To provide an apparatus and method for allocating to a receiver.

In addition, the PN code synchronization tracking method in the CDMA mobile communication base station system according to the present invention is characterized in that the PN code synchronization tracking in the CDMA mobile communication base station system having a DSP, an ATM including a match filter and a memory, and a demodulator. CLAIMS 1. A method comprising: transmitting, at a DSP, a search section and an integration section as parameters to the ATM; Calculating an energy value for each chip of the search section using the match filter according to the parameters of the search section and the integration section transmitted from the DSP; Storing the calculated energy value of each chip in the memory of the ATM; Comparing, by the DSP, an energy value of each chip stored in the memory by an interrupt and comparing the energy value of each chip with a predetermined threshold value; As a result of the comparison, if there is a value greater than a predetermined threshold value among the energy values of each chip, extracting any number of the largest value among the values greater than the threshold value; Transferring the extracted energy value to the demodulator to demodulate original data to complete an initial synchronization tracking process; When the initial synchronization tracking process is completed, the step of performing the second synchronization tracking process through the same process by setting the parameters of the search interval different from the search interval set in the initial synchronization tracking process.

1 is a block diagram of an apparatus for implementing a pseudo-noise code synchronization tracking method in a code division multiple access mobile communication base station system according to the present invention;

2 is a block diagram illustrating a detailed block configuration of the match filter shown in FIG. 1;

3 is a conceptual diagram of a pseudo noise code, a search section, and an integration section applied to the present invention;

4 is a flowchart illustrating an operation of a PN code synchronization tracking method in a CDMA mobile communication base station system according to the present invention.

<Explanation of symbols for main parts of drawing>

10: DSP 20: ATM

21: match filter 21a: code buffer

21b: data buffer 21c: adder

21d: Exclusive Or 22: Memory

Hereinafter, a PN code synchronization tracking method in a CDMA mobile communication base station system according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of an apparatus for implementing a pseudo-noise code synchronization tracking method in a code division multiple access mobile communication base station system according to the present invention, and FIG. 2 is a detailed view of the match filter shown in FIG. 1 and 2, the DSP 10, the ATM 20, and the demodulator 30 are configured, and the ATM 20 includes a matched filter. (21) and the memory (22).

Also, as shown in FIG. 2, the match filter 21 includes a code buffer 21a and a data buffer 21b composed of a plurality of shift registers, and values and data output from each shift register of the code buffer 21a. Each of the output values output from the plurality of exclusive or gates 21d and the plurality of exclusive orgates 21d respectively perform an exclusive-OR operation on the value output from the buffer 21b. It consists of the adder 21c to add.

An operation of the PN code synchronization tracking device in the CDMA mobile communication base station system having the above configuration will be described.

First, the present invention is implemented in a multi-mode demodulator board assembly (MMDA) in an IMT-2000 Cell Cite Subsystem (ICSS) block that is responsible for a demodulation function when implementing a next generation mobile communication system, that is, an IMT-2000 system. ) Is implemented as a main controller (Main Contriller) to track the PN code for initial synchronization and secondary synchronization.

In order to demodulate the signal modulated from the mobile station in the base station, the mobile station continuously tracks the movement path of the mobile terminal, selects the value with the largest energy, and selects the value of the base station demodulator 30 at the proper position of the PN code transmitted by the mobile station. You must match the PN code. Here, the PN code is a code maintained by both the mobile station and the base station, and is used as a code for distinguishing each base station, which is distinguished from each other by an offset value from the starting point. Therefore, it can be said that the purpose of initial synchronization and secondary synchronization is to find the offset value of the PN code.

In the initial synchronization, when the DSP 10 passes the integral section and the search section to the ATM 20 as parameters, the ATM 20 searches for the corresponding search section using this parameter. As shown in Fig. 3, the search section is set to 128 and the integration section is set to 512 chips. 3 is a conceptual diagram for a PN code, a search section, and an integration section.

A search section parameter value 128 as shown in FIG. 3 represents a search window size, and a section equal to the size of the search window from the start point of the PN code is obtained using the match filter 21 in the ATM 20. The integral section is repeated and the result is stored in the memory 22.

The above operation will be described in more detail.

The PN code currently maintained by the demodulator 30 has a window size determined by a search section from the start point, and an energy value is calculated by the match filter 2 by 512 chips, which is an integration section from the beginning chip of this section.

As shown in FIG. 2, the match filter 21 has a structure of 32 taps. The match filter 21 includes a code buffer 21a including 32 shift registers to which a PN code is input, and information bits coming from a terminal. It becomes the input data of the data buffer 21b consisting of 32 shift registers, and these data are calculated through the exclusive or 21d gate, and then input to the adder 21c to add all the signals. That is, the exclusive or operation is performed at each exclusive or gate 21d on the value output from each shift register of the code buffer 21a and the value output from each shift register of the data buffer 21b. The output values of the exclusive or gate 21d are input to the adder 21c, respectively, and are added together by the adder 21c.

In this way, the value added by the adder 21c becomes an energy value for the 32 PN chip.

Since the current integral section is 512 chips and the PN code is input in 32 tap units, the calculation process must be repeated 16 times in order to calculate the energy values for all the integral sections. The energy values for the 512 chips obtained through this iterative operation are added by the adder 21c and then stored in the memory 22 of the ATM 20. Therefore, the energy values for the last 128 search windows are output as a result. That is, since the energy value is calculated for each of the search periods determined as 128 by the match filter 21 for each chip unit, a total of 128 results are obtained as shown in FIG. 3.

The ATM 20 delivers all of these 128 results to the DSP, and the DSP 10 sequentially compares the 128 energy result values output from the ATM 20 with a preset threshold value and sequentially converts energy values larger than the threshold value. Extract at least four.

If, as a result of the comparison, there is no energy value larger than the threshold value, it is determined that no mobile station sends a signal in the corresponding search section, and the process proceeds to the next 128 chip search section.

At least four or more result values extracted as the above result are input to the demodulator 30 in the MMDA for demodulation and demodulated to the original data.

As described above, when the initial synchronization tracking process is completed, the secondary synchronization tracking process is performed. The secondary synchronization tracking process is the same as the initial synchronization tracking process, and the function of accurately matching the PN code phase difference of the transceiver achieved in the initial synchronization device is performed. At the same time, it also maintains a synchronized motivation.

In the second synchronous tracking process, since the top color section is 32 chips and the sample input to the data buffer 21b is input with 4 over samples, the result of 32 PN chips is obtained. That is, as shown in FIG. 3, in the initial synchronization mode in which the search section is 128 chips and the integration section is 512 chips, energy values are calculated by the integration section in units of chips from the starting point of the search section. 128 search results are output because the search section is 128 chips. In the second synchronous tracking mode, 32 search results are output because the search section is 32 chips.

When 32 of the result values are transmitted to the DSP 10 in the order of the largest value, the DSP 10 transfers the result values to the demodulator 30 in the MMDA. Therefore, the demodulator 30 demodulates the result value transmitted from the DSP 10 into original data.

A PN code synchronization tracking method in a CDMA mobile communication base station system according to the present invention corresponding to the above operation will be described step by step with reference to FIG.

4 is a flowchart illustrating an operation of a PN code synchronization tracking method in a CDMA mobile communication base station system according to the present invention.

First, the DSP 10 transfers the search section and the integration section to the ATM 20 as parameters (S101). Here, the search section is set to 128 chips, and the integration section is set to 512 chips.

Subsequently, the ATM 20 calculates an energy value for each chip in the search section transmitted from the DSP 10 (S102). That is, 128, the search interval parameter value, indicates the size of the search window, and the search window size from the starting point of the PN code is set to the energy value corresponding to the integration interval using the match filter 21 in the ATM 20. The calculation is repeated and the result is stored in the memory 22.

The PN code currently maintained by the demodulator 30 has a window size determined by a search section from the start point, and an energy value is calculated by the match filter 2 by 512 chips, which is an integration section from the beginning chip of this section.

Since the current integral section is 512 chips and the PN code is input in 32 tap units, the calculation process has to be repeated 16 times in order to calculate the energy values for all the integral sections. The energy values for the 512 chips obtained through this iterative operation are added by the adder 21c and then stored in the memory 22 of the ATM 20. Therefore, the energy values for the last 128 search windows are output as a result. That is, since the energy value is calculated for each of the search periods determined as 128 through the match filter 21 for each chip unit, a total of 128 results are obtained as shown in FIG. 3.

Subsequently, the energy value for each chip calculated by the above method is stored in the memory 22 in the ATM 20 (S103), and the DSP 10 receives the energy value for each chip stored in the memory 22 by an interrupt. In operation S104, all of the read energy values of each chip are compared with a predetermined threshold value (S105).

Subsequently, it is determined whether there is a value larger than a predetermined threshold value among the energy values for each chip, and if there is a large value, whether the number of large values is greater than or equal to the predetermined number (S106).

As a result of determination, if there is no value greater than the predetermined threshold among the energy values of each chip, it is determined that no mobile station transmits a signal in the corresponding search section, and moves to the next chip section to perform the same process as above (S107). If it is determined that there is a value larger than the preset threshold among the calculated energy values of each chip, and the number is greater than the preset number, the preset number of values greater than the threshold among the energy values of each chip, that is, at least four or more values To extract (S108).

Subsequently, the extracted at least four energy values are output to the demodulator 30 to demodulate the original data, thereby searching for an optimal path and completing an initial tracking process (S109).

As such, when the initial synchronization tracking process is completed, the second synchronization tracking mode is operated (S110). At this time, since the top color section in the second synchronization tracking process is 32 chips, the second synchronization tracking process is performed through the same process as the initial synchronization tracking process described above as the search interval of the 32 chips. At this time, in the second synchronous tracking process, the energy result value of each chip is 32.

The PN code synchronization tracking method in the CDMA mobile communication base station system according to the present invention as described above, while maintaining the synchronization to the assigned path, such as the code recognition part or the code tracking loop used in the conventional method for the path This approach is different from the method of demodulating data by obtaining channel estimates. That is, the DSP 10 obtains channel estimation results and energy values for all possible paths within a time interval corresponding to a delay profile, and continuously upgrades information on the best path. The DSP 10 extracts the highest energy path and transfers it to the demodulator 30 to maximize the performance of the receiver.

In the PDMA code synchronization tracking method in the CDMA mobile communication base station system according to the present invention, when the DSP passes the search section and the integration section as parameters to the ATM, the ATM uses the match filter to provide energy for all paths. When the value is obtained and the energy value is transferred back to the DSP, the DSP extracts at least four or more values greater than the threshold value from the energy values and passes them to the demodulator. Finding the best route. Therefore, the following effects will be obtained.

First, since the result values for the initial synchronization and the secondary synchronization are reported to the DSP, there is an advantage that the software can be more flexibly operated. In this case, the flexibility means that the result value reported to the DSP is processed by software and used for channel estimation.

Second, an ATM operating by receiving parameters such as a search section and an integration section delivered by a DSP has an advantage of allocating the best path by performing synchronization tracking for all paths from the terminal through a match filter.

Claims (6)

A PN code synchronization tracking method in a CDMA mobile communication base station system having a DSP, an ATM including a match filter and a memory, and a demodulator, Transmitting, at the DSP, a search section and an integration section as parameters to the ATM; Calculating an energy value for each chip of the search section using the match filter according to the parameters of the search section and the integration section transmitted from the DSP; Storing the calculated energy value of each chip in the memory of the ATM; Comparing, by the DSP, an energy value of each chip stored in the memory by an interrupt and comparing the energy value of each chip with a predetermined threshold value; As a result of the comparison, if there is a value greater than a predetermined threshold value among the energy values of each chip, extracting an arbitrary number of the largest energy value among the values larger than the threshold value; Transferring the extracted energy value to the demodulator to demodulate original data to complete an initial synchronization tracking process; When the initial synchronization tracking process is completed, the step of performing a second synchronization tracking process through the same process by setting the parameters of the search interval different from the search interval set in the initial synchronization tracking process A PN code synchronization tracking method in a CDMA mobile communication base station system. The method of claim 1, As a result of the comparison in the comparing step, if it is determined that the energy value for each chip is not larger than the preset threshold value, it is determined that there is no mobile station transmitting a signal in the corresponding search section, and then moves to the next search section to track initial synchronization. PN code synchronization tracking method in a CDMA mobile communication base station system characterized in that the process and the secondary synchronization tracking process. The method of claim 1, The PN code synchronization tracking method of the CDMA mobile communication base station system, characterized in that the parameter value of the search section and the integration section transmitted from the DSP to the ATM in the initial synchronization tracking process. The method of claim 1, The calculating of the energy value for each chip may include performing an exclusive or operation on each PN code of a search section for a 32PN chip transmitted from the DSP and each information bit transmitted from the terminal; And calculating an energy value for each chip corresponding to a chip of each search section by adding all the calculation result values. The method of claim 1, The number of extracted energy value in the step of extracting the energy value is PN code synchronization tracking method in a CDMA mobile communication base station system, characterized in that at least four. The method of claim 1, In the energy value calculation step, a single energy value is calculated in units of 32 taps, and a 128-energy value corresponding to a search period is extracted by repeating the recalculation process by an integral period. PN code synchronization tracking method.