KR100611096B1 - User identification method using cyclic masking code on base station side - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method for identifying a base station user using a cyclic masking code and a computer readable recording medium having recorded thereon a program for realizing the method.

2. The technical problem to be solved by the invention

The present invention, by using a cyclic masking code (Cyclic Masking Code) in the mobile communication system to distinguish the base station users and at the same time also performs a fast Fourier transform (FFT) frame synchronization, to reduce the complexity in the implementation of the receiver to improve the performance A computer-readable recording medium recording a base station user identification method and a program for realizing the method.

3. Summary of Solution to Invention

According to an aspect of the present invention, there is provided a method for identifying a base station user in a mobile communication system, the method comprising: a first step of identifying a user of a reverse link receiver by injecting a cyclic masking code into a protection interval injected as a protection against multipath interference; A second step of obtaining respective codes used by the divided users to detect the data of the guard interval among the data received before the fast Fourier transform (FFT) and then reverse masking the received data; In the reverse masking of the received data, the absolute value is obtained by subtracting the reception size of the reverse masked data and the copied guard interval data using the property that the energy value is the largest when despreading to its own code according to the orthogonal code. Obtaining a third step; And performing the third step between each unit sample while moving for the corresponding sample corresponding to one symbol, and simultaneously setting the size of the observation interval and performing this over a predetermined guard interval, thereby starting the fast Fourier transform (FFT) frame. And a fourth step of obtaining frame synchronization.

4. Important uses of the invention

The present invention is used for high speed WATM implementation using MC-CDMA.

User Division, MC-CDMA, WATM, Fast Fourier Transform, Masking

Description

User identification method using cyclic masking code on base station side}             

1 is an explanatory diagram showing a process of generating a cyclic masking code for identifying a conventional base station user;

2 is a diagram illustrating an embodiment of a cyclic masking code generation process for identifying a base station user according to the present invention;

Figure 3 is a configuration diagram of an embodiment of a cyclic masking code generating apparatus for identifying a base station user used in the present invention.

4 is a flowchart illustrating an embodiment of a method for identifying a base station user according to the present invention;

The present invention realizes a base station user classification method and the method that can distinguish the base station users by using a cyclic masking code (CFT) in the mobile communication system and at the same time synchronize the Fast Fourier Transform (FFT) frame The present invention relates to a computer-readable recording medium having recorded thereon a program.

In particular, the present invention is one of the Orthogonal Frequency Division Multiplexing (OFDM) / Code Division Multiple Access (CDMA) scheme for implementing the Wideband Asynchronous Transfer Mode (WATM) scheme. Multi-carrier CDMA (MC-CDMA) enables high-speed WATM implementation, and in this case, one of the biggest problems in the implementation is the division of users within the same cell radius in the base station receiver And at the same time a fast Fourier transform (FFT) frame synchronization.

Recently, as the multimedia services have been diversified, high-speed data transmission is required, and at the same time, as the demand of consumers increases according to the construction of the wireless network, the market of WATM expands, so that appropriate technology is implemented and It is necessary to learn.

At the same time, various countries are making various types of organizations for WATM standardization, and various approaches have been approached for macroscopic expansion of standardization for WATM implementation.At the same time, an OFDM scheme is used to implement such high-speed data transmission technology. The research on is actively being conducted.

In each country, various technologies are developed and prepared for practical use for the implementation of WATM, and the OFDM / TDMA method, which has accumulated existing technologies in various forms as data modulation / demodulation technology, is the basis. However, the conventional method has a weak point in terms of frequency utilization, which is a disadvantage of the TDMA method, and recently, MC-CDMA method, which is one of OFDM / CDMA methods, has been newly proposed to compensate for such disadvantages. It is expected to apply.

The biggest problem in receiving the reverse link of the system using MC-CDMA is that the form transmitted from each user at the time of reception is transmitted asynchronously in the reverse direction, which makes it difficult to distinguish each terminal user. In the case of MC-CDMA transmission, the synchronization technique that closes the starting point of the FFT of the receiving apparatus has the greatest effect on system demodulation. In the conventional scheme, the receiving apparatus of the reverse link inserts and transmits additional information for user identification. The data rate is reduced, and the complexity of the system is increased and the computational amount is increased by performing different user classification and FFT synchronization.

For example, as shown in FIG. 1, when receiving a reverse link, data called a SYNC BURST is injected after insertion of a guard interval to distinguish a user. This insertion of additional information may reduce data transmission efficiency. In addition, since the FFT frame synchronization is obtained again by using the guard interval after demodulating the user for demodulation at the time of reception, the hardware configuration is complicated and the calculation amount is increased.

In order to solve the above problems, the present invention distinguishes a base station user using a cyclic masking code in a mobile communication system and simultaneously performs fast Fourier transform (FFT) frame synchronization, It is an object of the present invention to provide a base station user classification method for reducing complexity and improving performance thereof and a computer-readable recording medium recording a program for realizing the method.

In order to achieve the above object, the present invention provides a method for distinguishing a user of a reverse link receiver by injecting a cyclic masking code into a protection interval for injecting a protection means for multipath interference in a base station user classification method of a mobile communication system. Stage 1; A second step of obtaining respective codes used by the divided users to detect the data of the guard interval among the data received before the fast Fourier transform (FFT) and then reverse masking the received data; In the reverse masking of the received data, the absolute value is subtracted by subtracting the reception size of the reverse masked data and the copied guard interval data by using the property that the energy value is greatest when despreading to the own code according to the orthogonal code. Obtaining a third step; And performing the third step between each unit sample while moving for the corresponding sample corresponding to one symbol, and simultaneously setting the size of the observation interval and performing this over a predetermined guard interval, thereby starting the fast Fourier transform (FFT) frame. It is characterized by comprising a fourth step of obtaining the frame synchronization.

In addition, the present invention provides a mobile communication system having a processor, comprising: a first function of distinguishing a user of a reverse link receiver by injecting a cyclic masking code into a protection interval for injecting protection for multipath interference; A second function of acquiring codes used by the divided users to detect the data of the guard interval among the data received before the fast Fourier transform (FFT), and then reverse mask the corresponding received data; In the reverse masking of the received data, the absolute value is subtracted by subtracting the reception size of the reverse masked data and the copied guard interval data by using the property that the energy value is greatest when despreading to the own code according to the orthogonal code. Obtaining a third function; And performing the third function while moving the corresponding sample corresponding to one symbol between every unit sample, and simultaneously setting the size of the observation interval and performing it over a predetermined guard interval, thereby starting the fast Fourier transform (FFT) frame. The present invention provides a computer-readable recording medium having recorded thereon a program for realizing a fourth function of obtaining frame synchronization.

The present invention facilitates the identification of users in the implementation of a reverse receiver using the next-generation technology or the MC-CDMA scheme, and improves data transmission efficiency by not inserting additional information amount, and at the same time, user identification and data reception demodulation. By simultaneously performing the preceding FFT frame synchronization, it is possible to reduce the complexity in the implementation of the receiver and improve its performance.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention does not inject information corresponding to additional information for user division into the transmitter of the MC-CDMA reverse transmitter as in the conventional scheme, and protects the conventional OFDM transmitter as a protection against multipath interference. By injecting a cyclic masking code rather than additional information (synchronous burst data) into the interval, it is possible to distinguish a user of the reverse receiver. At this time, the most important is to maintain the nature of the cyclic prefix (protection from the original multipath interference).

Another feature of the present invention is to perform step-by-step FFT frame synchronization technique, which is a synchronous technique that is preceded for data demodulation after user division, after the injection of the additional information amount for the existing user division, the present invention by using a cyclic masking code Simultaneously with the user identification in the backward receiver, the frame synchronization to find the starting point of the FFT frame is performed, which not only simplifies the circuit but also reduces the computational amount.

A process of generating the cyclic masking code is shown in FIG. 2.

Referring to FIG. 2, the present invention increases the data rate by utilizing user classification information with a smaller amount of information than the method of FIG. 1.

As shown in FIG. 2, each user terminal masks with a different orthogonal code in the conventional guard interval data. Here, not the concept of spreading, it refers to a process of applying a user code to the original guard interval data once more by operating a code generator at the same rate as each symbol rate.

As such, an apparatus for generating a cyclic masking code for identifying users is illustrated in FIG. 3.

Then, a process of identifying the base station user using the cyclic masking code will be described in more detail.

4 is a flowchart illustrating a method for identifying a base station user according to the present invention.

The base station acquires a code used by each user to distinguish the users, first detects data of the protection section from the received data in front of the FFT, and then reverse masks the received data. In this case, the absolute value is obtained by subtracting the reception sizes of the reverse masked data and the copied guard interval data by using the property that the energy value is the largest when despreading to the own code due to the property of the orthogonal code at the time of reverse masking. .

This process is performed for every unit sample while moving for N samples corresponding to OFDM 1 symbols, and at the same time, the size of the observation interval is determined and performed over several guard intervals.

In more detail, as shown in FIG. 4, if the OFDM symbol length is N, after storing received data of 2N + G (401), the initial guard interval data is taken to reverse N user codes simultaneously. Matching filtering, which is a process of masking and summating, and then checking which code the output value of the matching filter is large for each user code is examined while transitioning the guard interval (402 to 405). At this time, the transition region of the protection section calculates the maximum value while calculating the output value of the matching filter in parallel by N + G (protection section). In this case, the user code is a code that provides an output value corresponding to the obtained maximum value.

In addition, assuming that the SHIFT value is ni, at this time, when "MAX (ni) -G / 2≤Wn≤MAX (ni) + G / 2" based on ni, Wn is an observation function region. In this region, while the guard interval is moved once again, the correlation between the original signal of the despread data and the copied original received signal is obtained, and the Wn value providing the largest value is estimated as the starting point of the FFT window at the time of despreading. 406 to 410).

The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains, and the above-described embodiments and accompanying It is not limited to the drawing.

As described above, the present invention has the effect of simplifying the circuit and reducing the amount of computation in implementation by simultaneously performing frame synchronization to obtain the starting point of the FFT frame at the same time as the user identification in the reverse receiver by using the cyclic masking code. .

Claims (2)

In the base station user identification method of the mobile communication system, A first step of identifying a user of a reverse link receiver by injecting a cyclic masking code into a protection interval for injecting protection for multipath interference; A second step of obtaining respective codes used by the divided users to detect the data of the guard interval among the data received before the fast Fourier transform (FFT) and then reverse masking the received data; In the reverse masking of the received data, the absolute value is subtracted by subtracting the reception size of the reverse masked data and the copied guard interval data by using the property that the energy value is greatest when despreading to the own code according to the orthogonal code. Obtaining a third step; And The third step is performed between each unit sample during the corresponding sample corresponding to one symbol, and at the same time, the size of the observation interval is performed over a predetermined guard interval, thereby determining the starting point of the fast Fourier transform (FFT) frame. Fourth Step to Acquire and Synchronize Frames Base station user classification method using a cyclic masking code comprising a. In a mobile communication system having a processor, A first function of distinguishing a user of a reverse link receiver by injecting a cyclic masking code into a protection interval for injecting protection for multipath interference; A second function of acquiring codes used by the divided users to detect the data of the guard interval among the data received before the fast Fourier transform (FFT), and then reverse mask the corresponding received data; In the reverse masking of the received data, the absolute value is subtracted by subtracting the reception size of the reverse masked data and the copied guard interval data by using the property that the energy value is greatest when despreading to the own code according to the orthogonal code. Obtaining a third function; And The third function is performed for each unit sample during the corresponding sample corresponding to one symbol, and at the same time, the size of the observation interval is performed over a predetermined guard interval to determine the starting point of the fast Fourier transform (FFT) frame. Fourth function to obtain frame synchronization A computer-readable recording medium having recorded thereon a program for realizing this.

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