KR100867356B1 - Gia cazac cdma system using guard interval added constant amplitude zero auto-correlation code division multiple access and transmitting and receiving method thereof - Google Patents

Abstract

A GIA CAZAC(Guard Interval Added Constant Amplitude Zero Auto-Correlation) CDMA system and a transmitting and receiving method thereof are provided to improve a signal to noise ratio of a user terminal by removing a signal of other user in an integral process of a receiver. A GIA CAZAC CDMA system includes a GIA CAZAC CDMA transmitting terminal and a GIA CAZAC CDMA receiving terminal. The GIA CAZAC CDMA transmitting terminal conforms the GIA CAZAC CDMA symbol synchronization, generates the GIA CAZAC sequence, and modulates a base band for receiving request data transmission ratio. The GIA CAZAC CDMA transmitting terminal multiplexes the GIA CAZAC sequence by the baseband signal and multiplies the multiplied result by the radio frequency and transmits the final result. The GIA CAZAC CDMA receiving terminal converts a wireless frequency into a spread spectrum signal, generates the GIA CAZAC conjugate sequence, and multiplies the spread spectrum signal by the GIA CAZAC conjugate sequence, and demodulates the baseband.

Description

GIA CAZAC CDMA System Using Guard Interval Added Constant Amplitude Zero Auto-Correlation Code Division Multiple Access and Transmitting and Receiving Method Thereof}

The present invention relates to a system for providing a code division multiple access communication method in which a guard interval sequence is added to remove mutual interference between mobile terminals, and a method for transmitting and receiving the same.

The present invention provides a GIA CAZAC (Guard Interval Added Constant Amplitude Zero Auto-Correlation) Code Division Multiple Access (CDMA) system that provides a CAZAC code division multiple access communication scheme with an additional guard interval sequence. In more detail, the present invention relates to a transmission / reception method, and more specifically, to a sequence using a CAZAC (CAZAC; Constant Amplitude Zero Auto-Correlation) sequence, generating an orthogonal sequence added with a guard interval sequence, and using a synchronized sequence in a mobile terminal. The present invention relates to a system and a method for maintaining the cross-correlation property of a CAZAC orthogonal sequence even with respect to multiple signals of another terminal having a time difference by a multipath from a terminal to a base station, thereby eliminating mutual interference between mobile terminals.

The conventional technology of mobile communication is a method of suppressing other user interference, and there is a multi-user detection method. However, this method removes an interference signal by detecting other user signals and subtracts the received signal from a received signal. The concept was developed as a way to accommodate more users by receiving more, but the application is insignificant due to the complexity and difficulty of implementation.

In addition, in the conventional code division multiple access system, the power control between users has a great effect on the system performance. In the conventional code division multiple access system, when a user's transmission signal is received by a base station, it acts as an interference signal.

The code division multiple access mobile communication terminal according to the prior art generates mutual interference signals with the terminal, and the magnitude of the interference energy for the other terminal is 1 / P.G times the desired signal. Where P.G stands for Process Gain. Eliminating the mutual interference power for one terminal improves the signal-to-noise ratio for the signal of the mobile terminal received from the base station, and the mobile terminal has sufficient margin for RF power. With this margin of mobile terminal RF power, quadrature amplitude modulation is not based on binary phase-shift keying (BPSK) or quadrature phase shift keying (QPSK). Even if the transmission speed is increased by using a method such as Quadrature Amplitude Modulation (QAM), there is a link margin, so that a bit error rate (BER) similar to that of the conventional system can be maintained. Therefore, the base station can process a lot of throughput (Throughput) with the same bandwidth. The number of concurrent users may increase, but this is limited by the number of orthogonal sequences that can occur. Increasing the number of users is possible by increasing the gain processing of the mobile terminal and using a high efficiency modulation method such as quadrature amplitude modulation (QAM) for the baseband modulation method of the mobile terminal.

It is not possible to maintain orthogonality between sequences of each user simply by keeping the conventional mobile communication code division multiple access terminal with sequence synchronization with the CAZAC orthogonal sequence, and it is necessary to add the guard interval sequence to the CAZAC sequence to complete the sequence even in a multipath environment. Orthogonality can be maintained.

The present invention has been conceived in that it is possible to eliminate interference noise by allowing other terminals to maintain orthogonal characteristics of sequences using CAZAC sequences for multiple signals having time differences by multiple paths. It is intended to improve bit error rate (BER) performance. If the BER performance of the mobile station received from the base station is improved, high quality, reliable communication system operation will be possible, and the signal-to-noise ratio of the mobile station is improved as the interference interference is reduced, thereby reducing power consumption of the mobile station. I can afford it. By using the link margin, the use of Quadrature Amplitude Modulation (QAM) as the baseband modulation method of the mobile terminal can improve the throughput at a base station with similar communication quality as the conventional method.

The present invention has been made to solve the problems of the prior art as described above, the present invention is to maintain the orthogonality of the sequence with respect to the interference signal of another terminal having a time difference by the multi-path and the front and rear two It is an object of the present invention to provide a GIA CAZAC (Guard Interval Added Constant Amplitude Zero Auto-Correlation) Code Division Multiple Access (CDMA) system and a method for transmitting / receiving an interference between symbols. .

GIA providing CAZAC (Constant Amplitude Zero Auto-Correlation, CAZAC) code division multiple access communication method to which a guard interval sequence is added according to an embodiment for achieving the object of the present invention as described above. In GAZ CAZAC (Guard Interval Added Constant Amplitude Zero Auto-Correlation, GIA CAZAC) Code Division Multiple Access (CDMA) system, the GIA CAZAC CDMA system is configured to perform GIA CAZAC CDMA symbol synchronization. A GIA CAZAC CDMA transmitter for generating a GIA CAZAC sequence, for baseband modulation capable of accommodating the required data rate, for multiplying the GIA CAZAC sequence with the baseband signal, and for multiplying the radio frequency; And a GIA CAZAC CDMA receiver for processing the radio frequency to convert to a spread band signal, generating a GIA CAZAC conjugate sequence, multiplying the spread band signal by a GIA CAZAC conjugate sequence, and performing baseband demodulation. A GIA CAZAC CDMA system is provided.

Advantageously, the GIA CAZAC CDMA transmitter comprises time measuring means for synchronizing GIA CAZAC CDMA symbol synchronization; Means for generating a GIA CAZAC sequence; Baseband modulation means capable of accommodating a required data rate; Means for multiplying a GIA CAZAC sequence and a baseband signal; And means for multiplying and transmitting the radio frequency.

Preferably, in the transmitting end, the GIA CAZAC sequence has a structure in which a guard interval sequence is added by cyclically extending the CAZAC sequence and the CAZAC sequence.

Preferably, in the transmitting end, the GIA CAZAC CDMA transmission symbol interval is characterized by a sum of one CAZAC sequence and a guard interval sequence.

Preferably, the GIA CAZAC CDMA sequence for identifying the first user in the transmitting end is generated and added to the guard interval sequence based on the CAZAC sequence, the sequence for distinguishing the second user is a sequence generated by shifting the CAZAC sequence The guard interval sequence is generated and added based on the synchronization of the symbol interval generated in each terminal, and maintains the orthogonality between symbols and the orthogonality between different users for the multi-delay signal by the multipath.

Advantageously, the GIA CAZAC CDMA receiving end comprises means for processing a radio frequency to convert it into a spread band signal; Means for generating a GIA CAZAC conjugate sequence; Means for multiplying the spreadband signal by the GIA CAZAC conjugate sequence; And means for baseband demodulation.

Preferably, the receiving end of the GIA CAZAC CDMA received signal is an integral section of the GIA CAZAC CDMA symbol section except for the guard period, and the interference signal of the other user who is synchronized is integrated with the GIA CAZAC CDMA integration section. In the process, only a slight interference due to the autocorrelation characteristic of one cycle of the CAZAC sequence is characterized by maintaining orthogonality between user signals.

Preferably, in the receiver, a desired signal and a delayed signal among the GIA CAZAC CDMA received signals have only a slight interference according to the autocorrelation characteristics of one cycle of the CAZAC sequence, and thus orthogonality between signals arrived after a time delay within a guard interval sequence time. It is characterized in that to maintain.

In the transmitter of a GIA CAZAC CDMA system providing a CAZAC code division multiple access communication method with a guard interval sequence added according to another embodiment for achieving the object of the present invention, the transmitter is a GIA CAZAC CDMA symbol Time measuring means for synchronizing synchronization; Means for generating a GIA CAZAC sequence; Baseband modulation means capable of accommodating a required data rate; Means for multiplying a GIA CAZAC sequence and a baseband signal; And means for multiplying and transmitting the radio frequency to provide a transmitting end of the GIA CAZAC CDMA system.

Preferably, in the transmitting end, the GIA CAZAC sequence has a structure in which a CAZAC sequence and a CAZAC sequence are cyclically extended to add a guard interval sequence.

Preferably, in the transmitting end, the GIA CAZAC CDMA transmission symbol interval is characterized by a sum of one CAZAC sequence and a guard interval sequence.

Preferably, in the transmitting end, the GIA CAZAC CDMA sequence for distinguishing users uses the CAZAC sequence as sequences generated by shifting the number of guard interval sequence chips or more, and each user sequence has an additional guard interval sequence. The synchronization of the symbol period generated in each terminal is consistent, and the orthogonality between symbols and the orthogonality between different users are maintained for the multiple delay signals due to the multipath.

In a receiving end of a GIA CAZAC CDMA system providing a CAZAC code division multiple access communication method with a guard interval sequence added according to another embodiment for achieving the object of the present invention, the receiving end processes the radio frequency Means for converting into a spread spectrum signal; Means for generating a GIA CAZAC conjugate sequence; Means for multiplying the spread band signal by the GIA CAZAC conjugate sequence; And a means for baseband demodulation, for receiving a GIA CAZAC CDMA system.

Preferably, the receiving end of the GIA CAZAC CDMA received signal is an integral section of the GIA CAZAC CDMA symbol section except for the guard period, and the interference signal of the other user who is synchronized is integrated with the GIA CAZAC CDMA integration section. In the process, only a slight interference due to the autocorrelation characteristic of one cycle of the CAZAC sequence is characterized by maintaining orthogonality between user signals.

Preferably, in the receiving end, the desired signal and the delayed signal among the GIA CAZAC CDMA received signals have only a slight interference according to the autocorrelation characteristic of one cycle of the CAZAC sequence, resulting in a time delay within the guard interval sequence time, It is characterized by maintaining orthogonality.

In a transmission method of a GIA CAZAC CDMA system providing a CAZAC code division multiple access communication method with a guard interval sequence added according to another embodiment for achieving the object of the present invention as described above, the transmission method is a GIA CAZAC A time measurement process of matching CDMA symbol synchronization; Generating a GIA CAZAC sequence; A baseband modulation process that can accommodate the required data rate; Multiplying the GIA CAZAC sequence by the baseband signal; And it provides a transmission method of the GIA CAZAC CDMA system, characterized in that it comprises a transmission process of multiplying and transmitting the radio frequency.

Preferably, in the above transmission method, the GIA CAZAC sequence has a structure in which a guard interval sequence is added by cyclically extending the CAZAC sequence and the CAZAC sequence.

Preferably, in the above transmission method, the GIA CAZAC CDMA transmission symbol interval is characterized by a sum of one CAZAC sequence and a guard interval sequence.

Preferably, in the above transmission method, a guard interval sequence is generated based on a CAZAC sequence and a GIA CAZAC CDMA sequence for distinguishing a first user is generated, and a sequence for distinguishing a second user is generated by shifting the CAZAC sequence. The guard interval sequence is generated and added based on the sequence, and the synchronization of the symbol interval generated in each terminal coincides, maintaining the orthogonality between symbols and the orthogonality between different users for the multi-delay signal due to the multipath.

In a receiving method of a GIA CAZAC CDMA system providing a CAZAC code division multiple access communication method with a guard interval sequence added according to another embodiment for achieving the object of the present invention, the receiving method is a radio frequency A conversion process of processing the signal into a spread band signal; Generating a GIA CAZAC conjugate sequence; Multiplying the spread-band signal by the GIA CAZAC conjugate sequence; And a demodulation process of baseband demodulation, in a GIA CAZAC CDMA system.

Preferably, in the above receiving method, an integral section of a GIA CAZAC CDMA received signal except a guard period of a GIA CAZAC CDMA symbol section is used as an integrated section, and the interference signal of another user who is synchronized is received with respect to a GIA CAZAC CDMA integrated section. In the integrating process, there is only a slight interference due to the autocorrelation characteristic of one cycle of CAZAC sequence, thereby maintaining orthogonality between user signals.

Preferably, in the above reception method, the desired signal and the delayed signal of the GIA CAZAC CDMA received signal have only a slight interference according to the autocorrelation characteristic of one cycle of the CAZAC sequence, and thus arrive at a time delay within the guard interval sequence time. It is characterized by maintaining the orthogonality.

Another object of the present invention is to provide a computer-readable recording medium having recorded thereon a program for executing the transmission method of the GIA CAZAC CDMA system.

Another object of the present invention is to provide a computer-readable recording medium having recorded thereon a program for executing the reception method of the GIA CAZAC CDMA system.

As described above, in the GIA CAZAC CDMA system according to the present invention, the desired signals are accumulated during the integration process of the receiver, but the interference signals of different users are due to cross-correlation characteristics (= self-correlation characteristics) between the same CAZAC sequences. Only insignificant interfering signals were received as interfering energy, which significantly reduced the interfering signals compared to the prior art.

In addition, since the GIA CAZAC CDMA system according to the present invention maintains orthogonality between users, the user mutual interference is significantly reduced, and thus, even though the power of other users is somewhat strong, there is an advantage of receiving less interference. That is, in the conventional CDMA method, since there are many users in a single network, even if the power of the user terminal is increased, there is a limit to the improvement of the signal-to-noise ratio (SNR) due to mutual interference between users. In addition, there was a difficulty in continuously adjusting the power emitted from the entire network in real time, but the GIA CAZAC CDMA system according to the present invention greatly improves the signal-to-noise ratio of the user terminal because the signal of the other user is removed in the integration process of the receiver. It is possible to control power between users less sensitively than the conventional CDMA system while maintaining a high signal-to-noise ratio.

The GIA CAZAC CDMA system according to the present invention can obtain the above-mentioned advantages and effects regardless of the modulation scheme, but in particular, it is possible to use the QAM modulation scheme that requires high signal-to-noise ratio performance, thereby increasing the overall throughput of the system. have.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings and the contents described in the accompanying drawings, but the present invention is not limited or limited to the embodiments. Like reference numerals in the drawings denote like elements.

The GIA CAZAC (Guard Interval Added Constant Amplitude Zero Auto-Correlation (GIA CAZAC)) code division multiple access (CDMA) system is a GIA CAZAC-CDMA transmitter and a GIA CAZAC-CDMA system. It consists of a receiver.

Throughout the specification, the guard interval sequence is collectively referred to as GI CAZAC (Guard Interval CAZAC) or GI (Guard Interval), and the CAZAC with added guard interval sequence is collectively referred to as GIA CAZAC, and the code division multiple access system using GIA CAZAC is GIA. Collectively known as the CAZAC CDMA system.

In the present invention, a sequence used by each user for multiple access uses a sequence obtained by adding a guard interval sequence of several chips generated by cyclically extending the CAZAC sequence to a constant amplitude zero auto-correlation (CAZAC) sequence. . In detail, as shown in FIG. 1, the GIA CAZAC sequence including the GI CAZAC and the CAZAC generates a new CAZAC sequence by shifting the CAZAC sequence by at least n chips when the GI CAZAC is n chips, and newly generated CAZAC. By creating a new GI CAZAC with some sequence in sequence, you create a new GIA CAZAC sequence. The cyclic extension technique is a similar technique used in orthogonal frequency division modulation (OFDM), and is used as a modulation technique of a transmitter for a high speed transmission for separating orthogonal separation of subcarrier frequency and symbol time from each other. The cyclic extension method used for the guard interval sequence used in the present invention is used to give a sequence to each user's signal, and to suppress the interference to occur between users by orthogonal the signals between users. In addition, to allow the carrier phase difference between the user terminal, and also to maintain the orthogonality between sequences even for the difference in the distance between the direct wave between the base station and the terminal, the distance between the interference wave or the ambiguous time delay due to multiple paths Used.

At this time, as shown in Fig. 2 (a), the transmission symbol period is the same as the GIA CAZAC sequence period period. The transmitter multiplies and transmits a transmission symbol and a GIA CAZAC sequence. The receiving unit multiplies the received signal by the conjugated GIA CAZAC sequence, and as shown in FIG. 2 (b), degenerates the despread signal by using the original CAZAC sequence 1 period section excluding the guard interval sequence as the GIA CAZAC-CDMA symbol integration section. Integrate, dump and print.

As a result, the integrated output for the integral section of the received GIA CAZAC-CDMA symbol is the result of autocorrelation for one complete cycle of the CAZAC sequence. Since the interference signals of different users also constitute one cycle of another CAZAC sequence, the interference signals of other users maintain orthogonal relation of the sequences with respect to the desired signals. Therefore, the interference signal of another user has only slight interference due to the cross-correlation property of the orthogonal sequence.

3 is a diagram illustrating a GIA CAZAC CDMA terminal transmitter 100 according to the present invention.

As shown in FIG. 3, the GIA CAZAC-CDMA terminal transmitter 100 includes a baseband modulator 110, a GIA CAZAC sequence generator 120, a multiplication circuit 130, and an RF unit 140.

4 illustrates the GIA CAZAC CDMA sequence generator 120 in detail. As shown in FIG. 4, the GIA CAZAC sequence generator 120 of the transmitter 100 may include a storage device in which an initial value of a GIA CAZAC sequence is stored in advance. 121, for example, a register and a shift register 122 are configured to generate a GIA CAZAC sequence by receiving a symbol period, that is, a GIA CAZAC CDMA symbol timing signal, and perform cyclic expansion of the sequence.

In detail, the GIA CAZAC sequence cyclic extension copies the last few to several ten chips (number of chips equal to the number of chips in the GI sequence) generated in the CAZAC-sequence generating circuit as shown in FIG. 4 and inserts them at the beginning of the CAZAC sequence. You can get GIA CAZAC by circular expansion. To do this, a circular expansion sequence can be generated by assigning the initial value of the CAZAC sequence register to a value a few chips before the first sequence value and supplying a clock to each register.

The input symbol of the GIA CAZAC CDMA is multiplied by the GIA CAZAC sequence and the multiplication circuit 130, and the spread GIA CAZAC CDMA output signal is multiplied by the carrier frequency through the RF unit 140 and transmitted wirelessly.

Hereinafter, generation of a CAZAC sequence and a GIA CAZAC sequence will be described.

The CAZAC sequence is generated by reading from top to bottom from left column to right from the following equation.

(Equation 1)

In other words, if you read the elements of Equation 1 according to the rules above

Is in order. References related to this technique can be found in R. C. Heimiller, "Phase Shift Pulse Codes with Good Periodic Correlation Properties", IRE Transactions on Information Theory, 1961. Oct. For example, when p = 4, a CAZAC sequence of length 16 is generated, which is a sequence of the following values.

The GIA CAZAC sequence is created by copying the back part of the above Cn sequence and pasting it in front of the Cn sequence. If you make a GIA CASAC sequence Cn 'by copying the rear four chips of the Cn sequence,

시퀀스를 생성한 후,

시퀀스의 뒤쪽 일부를 복사하여

시퀀스의 앞쪽에 붙여 넣음으로써 생성된다. Becomes When generating another GIA CAZAC sequence, the original Cn sequence is delayed by k-chip cyclic delay.

After creating the sequence,

Copy the back part of the sequence

Created by pasting in front of a sequence.

For example, using the sequence Cn above, delaying 4 chips, and then creating a GIA CAZAC sequence (Cn (4) '),

Becomes

5 is a diagram illustrating a GIA CAZAC CDMA terminal receiver 200 according to the present invention.

As shown in FIG. 5, the terminal receiver 200 includes an RF unit 210, a GIA CAZAC conjugate sequence generator 220, a multiplier 230, and a baseband demodulator 240.

The GIA CAZAC conjugate sequence generator 220 may have the same structure as the sequence generator 120 of the transmitter 100. As shown in FIG. 6, the GIA CAZAC conjugate sequence generator 220 of the transmitter 200 is shown. Is composed of a storage device 221 (for example, a register) and a shift register (222) in which the initial value of the GIA CAZAC conjugate sequence is stored in advance, and receives a symbol period, that is, a GIA CAZAC CDMA symbol timing signal, to obtain a GIA CAZAC conjugate sequence. Can be generated. However, since the sequence is a complex value, a complex value which is a conjugate with the transmitter 100 should be a sequence. The conjugate complex sequence of the Cn sequence is represented by the Cn * sequence. Assuming that the synchronization or symbol period synchronization is correct, the received GIA CAZAC-CDMA RF signal is multiplied by the carrier and the GIA CAZAC sequence to output a despread signal. The output signal is input to the baseband demodulator 240. In the GIA CAZAC-CDMA symbol interval, only the original CAZAC sequence interval excluding the guard interval is demodulated to determine the symbol.

The following describes the interference noise suppression principle using the guard interval sequence.

The conventional CDMA method uses a signal spread by multiplying an input signal by a CDMA sequence. The CDMA sequence is considered to be a random sequence because it inserts zeros into the m-sequence and multiplies the walsh code, which significantly loses the characteristics of the original m-sequence. In addition, since the synchronization with respect to the symbol start time between mobile terminals is not synchronized, the sequence synchronization is not synchronized. Considering the operating environment of the mobile terminal, multiple signals of the mobile terminal having a time difference by the multipath arrive at the base station. In the end, these characteristics of the mobile terminal were considered to no longer require sequence synchronization. Sequences generated by multiplying two random sequences together are also random and spread. The interfering signal between the two sequences is spread out on the frequency axis on average, and the power density is reduced by the level of the interfering signal noise. The baseband and spreadband interference occurs at the same level.

(Equation 2)

배가 된다. 이를 잡음 전압으로 표현하면

이 된다. 원치 않는 랜덤한 시퀀스의 주파수 스펙트럼은 확산 대역 주파수 전체에 대해 평균적으로 동일한 레벨로 확산하여 낮은 레벨이 되고, 역 확산 시에도 그 레벨을 유지한다.As shown in Equation 2, through the process of spreading and despreading, the desired signal is restored to the original narrowband signal, while the other unwanted user interference signal energy is used per user.

It is doubled. If this is expressed as noise voltage

Becomes The frequency spectrum of an unwanted random sequence spreads to the same level on average throughout the spread band frequency, resulting in a low level, and maintains that level even during reverse spreading.

The generation of the GIA CAZAC sequence by adding a guard interval sequence to the original CAZAC sequence at the transmitter of the present invention is to suppress interference when the same signal is received more than once by multipath.

Table 1 shows the process of generating the 1 symbol signal of the first user. Assume that a signal is received twice in two paths, and the second signal has the same energy as the first signal. In addition, assume that the first signal and the second signal arrived by one chip. In the received signal, the sequence 1 cycle of the desired phase of the complete CAZAC-sequence and the sequence 1 cycle of the 1-chip delayed phase are present in the symbol integration period. The signal of one chip that is delayed in the protection interval and entered the integration period is related to the current symbol and has nothing to do with the previous symbol. The desired signal and the delayed interference signal maintain a shifted relationship of a complete cycle of the CAZAC-sequence, and the interference between the two signals depends on the autocorrelation characteristics of the CAZAC-sequence.

The autocorrelation characteristics of the CAZAC sequence are shown in FIG. 7, and when the sequence phase is exactly coincident, it has a very good magnetic inertia characteristic of 0 when one or more chips are released. Thus, the first signal that arrives for its signal and the second signal that arrives with a delay of more than one chip are completely separated from each other without mixing.

Table 1 Multipath Interference Noise in GIA CAZAC-CDMA System

This same signal separation capability applies even when there are two users. This is shown in Table 2. Let's say that the first user uses the Cn 'sequence, and the second uses the Cn'4 sequence, which delays and cyclically extends four chips from the original Cn sequence of the first user's Cn' sequence. The first arriving signal of the second user acts as one cycle of the complete CAZAC sequence, which is delayed by more than 4 chips compared to the first user sequence. This means that the second arrival signal of the second user also acts as one complete CAZAC sequence with a delay of at least 5 chips compared to the first user sequence, and the cross-correlation between one complete cycle of the CAZAC sequence depends on the autocorrelation property. In case of deviation, the autocorrelation value of the CAZAC sequence becomes 0, thereby eliminating user-interference.

Table 2 Interference Noise by Other Users of GIA CAZAC-CDMA System

Hereinafter, a method of determining a usage sequence for each user will be described.

The sequence used for each user is generated from the same GIA CAZAC sequence, and the user's division can be made from a sequence of several chip shifts of the GIA CAZAC sequence. There is only minimal interference due to autocorrelation between shifted GIA CAZAC sequences. Each user can be distinguished by user if the user shifts more than the number of chips necessary for the guard interval sequence. For example, if the period of the CAZAC sequence is 64, and the guard interval sequence is 5 chips, it can be allocated to each user at a distance of 6 chips, and the sequence can be allocated to 10 subscribers.

For example, if the system capacity increases and users need to be increased, for example, using CAZAC sequence period of 256, which is about 4 times larger than 64, and using 5 chips of the same guard interval sequence, if 6 chips are separated, 62 subscribers You can assign a sequence. In this case, since the length of the symbol is increased by four times, each user uses a modulation method such as QAM having four times the frequency efficiency.

Hereinafter, a method for determining a guard interval sequence length will be described.

The guard interval allows the same signal to arrive at different time intervals by multipath so that it does not overlap with other symbols before and after. When integrating over the symbol integration interval, the signal that arrived first and the signal that arrived later are separated from each other. The purpose is to separate them so that they do not affect each other. Therefore, the length of the guard interval sequence is set to allow time as much as the time between the influencing signals among the arriving signals with time difference. For example, if one signal is received twice with different paths and is received at intervals of one chip, it is necessary to add a guard interval sequence of two or three chips larger than one chip. Normally, it can be determined by the number of sequence chips occupying about two times the predictable time difference.

A transmission method and a reception method of a GIA CAZAC CDMA system which provide a CAZAC code division multiple access communication method with a guard interval sequence according to the present invention are implemented in a program instruction form that can be executed by various computer means. Can be recorded in a sieve. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. The medium may be a transmission medium such as an optical or metal wire, a waveguide, or the like including a carrier wave for transmitting a signal specifying a program command, a data structure, or the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

As described above, the present invention has been described by specific embodiments such as specific components and the like, but the embodiments and the drawings are provided only to help a more general understanding of the present invention, and the present invention is not limited to the above embodiments. For those skilled in the art, various modifications and variations are possible from such description.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and all the things that are equivalent to or equivalent to the claims as well as the following claims will belong to the scope of the present invention. .

1 is a diagram illustrating a generation step of a GIA CAZAC sequence.

FIG. 2 (a) is a diagram illustrating a period of a GIA CAZAC sequence, and FIG. 2 (b) is a diagram illustrating a symbol period and an integration period.

3 is a configuration diagram of a GIA CAZAC CDMA terminal transmitter;

4 is a configuration diagram of a GIA CAZAC CDMA sequence generator;

5 is a configuration diagram of a GIA CAZAC CDMA terminal receiver;

6 is a block diagram of a GIA CAZAC CDMA conjugate sequence generation unit;

7 is an example of autocorrelation characteristics of a CAZAC sequence.

Claims (17)

GIA CAZAC (Guard Interval Added Constant Amplitude Zero) provides Constant Division Amplitude Zero Auto-Correlation (CAZAC) code division multiple access (CDMA) communication with guard interval sequences Auto-Correlation) CDMA system, The GIA CAZAC CDMA system A GIA CAZAC CDMA transmitter that matches the GIA CAZAC CDMA symbol synchronization, generates a GIA CAZAC sequence, baseband modulates to accommodate the required data rate, multiplies the GIA CAZAC sequence with the baseband signal, and multiplies by the radio frequency; And a GIA CAZAC CDMA receiver; The GIA CAZAC CDMA receiving end comprises means for processing a radio frequency to convert the spread spectrum signal; Means for generating a GIA CAZAC conjugate sequence; Means for multiplying the spread band signal by the GIA CAZAC conjugate sequence; And means for baseband demodulation, The GIA CAZAC CDMA receiving end is an integral section of the GIA CAZAC CDMA received signal except for the guard period of the GIA CAZAC CDMA symbol section, and the interference signal of the other user who is synchronized is integrated with the GIA CAZAC CDMA integration section. GIA CAZAC CDMA system, characterized in that there is only a slight interference according to the autocorrelation characteristics of one cycle of the CAZAC sequence, to maintain orthogonality between user signals. The method of claim 1, wherein the GIA CAZAC CDMA transmitter is Time measuring means for matching the GIA CAZAC CDMA symbol synchronization; Means for generating a GIA CAZAC sequence; Baseband modulation means capable of accommodating a required data rate; Means for multiplying a GIA CAZAC sequence and a baseband signal; And GIA CAZAC CDMA system comprising means for multiplying and transmitting radio frequencies. The method of claim 2, A GIA CAZAC sequence has a structure in which a CAZAC sequence and a CAZAC sequence are cyclically extended to add a guard interval sequence. The method of claim 2, GIA CAZAC CDMA transmission symbol interval is a GIA CAZAC CDMA system, characterized in that the interval between the CAZAC sequence 1 period and the guard interval sequence interval. The method of claim 2, The GIA CAZAC CDMA sequence that distinguishes users uses the CAZAC sequence as sequences generated by shifting the number of guard interval sequence chips or more, and each user sequence has a guard interval sequence added. GIA CAZAC CDMA system, characterized in that the synchronization of the symbol interval generated in each terminal is consistent, maintaining the orthogonality between symbols and orthogonality between different users for the multi-delay signal by the multipath. delete delete The method of claim 1, Desired signal and delayed signal among GIA CAZAC CDMA received signals have only slight interference according to autocorrelation characteristics of one cycle of CAZAC sequence, so that time delay within guard interval sequence time is maintained and orthogonality between arrived signals is maintained. GIA CAZAC CDMA System. GIA CAZAC (Guard Interval Added Constant Amplitude Zero) provides Constant Division Amplitude Zero Auto-Correlation (CAZAC) code division multiple access (CDMA) communication with guard interval sequences Auto-Correlation) CDMA system transmission method, The transmission method A time measurement process of matching GIA CAZAC CDMA symbol synchronization; Generating a GIA CAZAC sequence; A baseband modulation process that can accommodate the required data rate; Multiplying the GIA CAZAC sequence by the baseband signal; And Including the transmission process of multiplying and transmitting the radio frequency, The GIA CAZAC CDMA sequence for distinguishing users uses the CAZAC sequence as sequences generated by shifting more than the guard interval sequence chip number, and each user's sequence has a guard interval sequence added to each other. The synchronization method, the transmission method of the GIA CAZAC CDMA system, characterized in that to maintain the orthogonality between symbols and orthogonality between different users for the multi-delay signal by the multipath. The method of claim 9, A GIA CAZAC sequence has a structure in which a CAZAC sequence and a CAZAC sequence are cyclically extended to add a guard interval sequence. The method of claim 9, The GIA CAZAC CDMA transmission symbol interval is a period in which one cycle of the CAZAC sequence and the guard interval sequence are combined. delete GIA CAZAC (Guard Interval Added Constant Amplitude Zero) provides Constant Division Amplitude Zero Auto-Correlation (CAZAC) code division multiple access (CDMA) communication with guard interval sequences Auto-Correlation) CDMA system reception method, The receiving method is Converting the radio frequency into a spread spectrum signal; Generating a GIA CAZAC conjugate sequence; Multiplying the spread-band signal by the GIA CAZAC conjugate sequence; And Baseband demodulation is performed, including a demodulation process, Among the GIA CAZAC CDMA received signals, the GIA CAZAC CDMA symbol section is an integral section except the protection section. The interference signal of another user, which is synchronized and received, has only slight interference according to the autocorrelation characteristic of one cycle of CAZAC sequence in the process of integrating the GIA CAZAC CDMA integration section, thereby maintaining orthogonality between user signals. Receiving method of GIA CAZAC CDMA system. delete The method of claim 13, Among the GIA CAZAC CDMA received signals, the desired signal and the delayed signal have only a slight interference according to the autocorrelation characteristics of one cycle of the CAZAC sequence, so that the delay is performed within the guard interval sequence time and the orthogonality between the arrived signals is maintained. Receiving method of GIA CAZAC CDMA system. A computer-readable recording medium having recorded thereon a program for executing the transmission method of the GIA CAZAC CDMA system according to any one of claims 9 to 11. A computer-readable recording medium having recorded thereon a program for executing the reception method of the GIA CAZAC CDMA system according to claim 13 or 15.

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