JP2012165252A - Transmitter, receiver, and communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitter capable of supporting plural rates while minimizing increase of the of required carrier waves and PAPR.SOLUTION: The transmitter compatible with a spread spectrum modulation system which performs FSK modulation by primary modulation is provided with: an FSK signal generation part 11 which generates an FSK symbol by the FSK modulation on information data; a transmission signal coupling section 12 which generates a transmission block by coupling plural FSK symbols in time domains so that the phases of respective FSK symbols become continuous; and a spreading part 14 which spreads the transmission block using a phase rotation sequence.

Description

  The present invention relates to a transmitter, a receiver, and a communication system compatible with a spread spectrum communication system.

One of the communication methods is a method called a spread spectrum method. This is a communication method in which a signal subjected to primary modulation is transmitted after being spread over a wide band by a spreading sequence, and an original modulated signal is obtained by the same spreading sequence on the receiving side, and has the following features.
-Since the signal cannot be demodulated without knowing the spreading sequence used on the transmission side, it is highly confidential.
・ Detectability is low because power density can be reduced by diffusion.
-Multiple users communicating at the same frequency and the same time can be multiplexed by using different spreading sequences for each user.

  Even in such a spread spectrum system, as in other communication systems, it is an important issue to reduce the peak-to-average power ratio (PAPR). Here, PAPR means the ratio of the average power and peak power of the signal. When the PAPR of a transmission signal is large in wireless communication, there is a problem that the influence of distortion due to the nonlinear amplifier becomes large and the characteristics deteriorate. Therefore, it is necessary to make the PAPR of the transmission signal as small as possible.

  In spread spectrum systems, PSK is often used for primary modulation. On the other hand, Patent Document 1 describes that not only PSK but also FSK is used for primary modulation. Since the FSK signal has a characteristic that power is always constant, it is considered that PAPR can be reduced by using FSK instead of PSK. However, if a signal is spread by a PN sequence or Gold sequence that is often used as a spreading sequence, there is a problem that the PAPR of the signal after spreading becomes large.

  Non-Patent Document 1 describes a method in which primary modulation is FSK and a phase rotation sequence is used as a spreading sequence. Here, in the M-value FSK, M of a plurality of carriers are allocated for creating the M-value FSK, and one of the M is selected according to information to be transmitted. In the method of Non-Patent Document 1, the M-value FSK signal created in this way is spread by a phase rotation sequence, and further, a CP (Cyclic Prefix) is added to the spread signal to form a block. Send. The CP is a copy of a predetermined number of symbols located at the rear end of the spread signal. As described above, in the method described in Non-Patent Document 1, one M-value FSK signal is transmitted per transmission block. Although the FSK signal has a characteristic that the power is always constant, since the present system only multiplies the FSK signal by the phase rotation sequence, the generated transmission signal also has a constant power. Therefore, in this method, the PAPR can be set to 0 dB.

JP-A-7-143031

Hiroyasu Sano, Noriyuki Fukui, Hiroki Kubo, “Study on direct spread spectrum system that can despread and demodulate on the frequency axis”, 2009 IEICE Communication Society, B-5-82.

However, Patent Document 1 and Non-Patent Document 1 do not describe supporting multiple rates. Let us consider supporting a plurality of rates in a spread spectrum system in which these FSKs are primary modulated. As one method of changing the rate, a method of changing the multi-level number M of FSK can be considered. In this case, for example, if M is doubled, the number of carriers to be used is doubled, but the number of transmission bits only increases by 1 bit at most, which is not efficient. For example, when M = 32, 5 (= log ₂ 32) bits are transmitted at a time, but if M is doubled and M = 64, 6 (= log ₂ 64) bits are transmitted at a time. Become. In this way, the number of carriers used is doubled (= 64/32), but the transmission rate is only 1.2 times (= 6/5) at most.

  Therefore, as another method, a method of realizing a plurality of types of rates by simultaneously transmitting a plurality of FSK symbols will be considered. For example, when two FSK symbols are transmitted simultaneously, two FSK symbols are created on the frequency axis. For example, if two FSK symbols with M = 32 are sent simultaneously, 10 bits (= 5 × 2) can be sent. In this way, when the number of carriers to be used is doubled to 64, the transmission rate can be doubled, and the frequency utilization efficiency is high compared to the above method (method of increasing the multi-value number M). However, the transmission signal is a superposition of two carrier waves. In general, the PAPR of a signal obtained by superposing a plurality of carrier waves increases and does not become 0 dB. Therefore, when such a method is used, the problem that PAPR becomes large arises.

  The present invention has been made in view of the above, and an object of the present invention is to provide a transmitter, a receiver, and a communication system capable of supporting a plurality of rates while suppressing an increase in the required number of carriers and PAPR as much as possible. .

  In order to solve the above-described problems and achieve the object, the present invention is a transmitter corresponding to a spread spectrum modulation system that performs FSK modulation by primary modulation, and performs FSK modulation on information data to perform FSK modulation. FSK signal generating means for generating symbols, combining means for generating a transmission block by combining a plurality of FSK symbols in the time domain so that the phases of the FSK symbols are continuous, and using the phase rotation sequence, And spreading means for spreading the transmission block.

  According to the present invention, it is possible to achieve both efficient use of frequency and support of multiple transmission rates, and the effect of being able to reduce the PAPR to 0 dB.

FIG. 1 is a diagram illustrating a configuration example of a communication system. FIG. 2 is a diagram illustrating a configuration example of the transmitter according to the first embodiment. FIG. 3 is a diagram illustrating a configuration example of signals transmitted and received in the communication system according to the first embodiment. FIG. 4 is a diagram illustrating an operation of combining FSK symbols. FIG. 5 is a diagram illustrating a configuration example of the receiver according to the first embodiment. FIG. 6 is a diagram illustrating an FSK symbol creation operation. FIG. 7 is a diagram illustrating a configuration example of a transmitter according to the second embodiment. FIG. 8 is a diagram illustrating a configuration example of a receiver according to the second embodiment.

  Hereinafter, embodiments of a transmitter, a receiver, and a communication system according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, the present invention can be applied to communication devices including wireless and wired.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a communication system (wireless communication system) according to the present embodiment. The communication system includes one or more transmitters 1 and a receiver 2. The transmitter 1 constitutes a transmission side communication device, and the receiver 2 constitutes a reception side communication device. Further, the transmitter 1 and the receiver 2 constituting the system of the present embodiment perform communication by FSK. In the present embodiment, description will be made assuming that the number of FSK symbols in one transmission block is S (≧ 1). This value S may be different for each transmitter 1. Each transmitter 1 spreads the FSK signal using different phase rotation sequences and transmits the spread signal. That is, the signal of each transmitter 1 is multiplexed by the code division multiplexing method.

  Next, the configuration and operation of each of the transmitter 1 and the receiver 2 will be described in detail.

(Description of transmitter)
FIG. 2 is a diagram illustrating a configuration example of the transmitter 1 according to the present embodiment. As illustrated, the transmitter 1 includes an FSK signal generation unit 11, a transmission signal combination unit 12, a phase rotation sequence generation unit 13, a spreading unit 14, a CP addition unit 15, a frequency conversion unit 16, an amplifier 17, an antenna 18, and parameters. A storage unit 19 is provided.

  The FSK signal generation unit 11 performs FSK modulation on the input information data. The transmission signal combining unit 12 combines a plurality of FSK symbols output from the FSK signal generation unit 11 together. The phase rotation sequence generation unit 13 generates a phase rotation sequence described later. The spreading unit 14 spreads the signal output from the transmission signal combining unit 12 using the phase rotation sequence output from the phase rotation sequence generation unit 13. The CP adding unit 15 adds a CP to the signal output from the spreading unit 14. The frequency converting unit 16 converts the frequency of the signal output from the CP adding unit 15. The amplifier 17 amplifies the signal output from the frequency conversion unit 16. The antenna 18 transmits the signal output from the amplifier 17 toward the receiver 2. The parameter storage unit 19 stores parameters indicating operating conditions of the FSK signal generation unit 11 and the transmission signal combination unit 12.

FIG. 3 is a diagram illustrating a configuration example of a signal transmitted between the transmitter and the receiver according to the present embodiment. Between the transmitter and the receiver, a signal in which a CP (Cyclic Prefix) of length N _cp is added to the head of transmission data of length N as shown in the drawing is transmitted. In the present embodiment, this is called a block. The CP is a copy of the rear end N _cp symbol of the transmission data of length N.

Hereinafter, the operation of the transmitter 1 will be described with reference to FIG. Here, it is assumed that the following is determined in advance between the transmitter 1 and the receiver 2.
-Number of FSK symbols per block S
・ Transmission data length N and CP length N _cp
The modulation multi-level number M _i of the i-th FSK symbol and the FSK symbol length N _i (1 ≦ i ≦ S)

  These values are held in the parameter storage unit 19 and referred to as necessary from other blocks. As will be described later, the following formula (1) needs to be established.

In the signal transmission operation in the transmitter 1, first, the FSK signal generation unit 11 generates an FSK symbol corresponding to the information data to be transmitted. Here, the FSK modulation multilevel number M _i and the FSK symbol length N _i are notified from the parameter storage unit 19. The created FSK symbol is output to transmission signal combining section 12.

The transmission signal combiner 12 combines the FSK symbols created by the FSK signal generator 11 in the time domain. FIG. 4 is a diagram illustrating an operation of combining FSK symbols. As illustrated, the transmission signal combining unit 12 combines S FSK symbols into a transmission signal (transmission data) having a length N. Therefore, the above formula (1) needs to be established. Incidentally, in determining the value of the FSK symbol length N _i and the transmission data length N between the transmitter 1 and the receiver 2, assumed to be determined as the equation (1) is satisfied.

Further, since the M _i value FSK symbol information of log ₂ M _i bits are transmitted, the first transmission block (those obtained by adding a CP to the signal of the S FSK length N bound obtained symbols), Information of the number of bits represented by the following equation (2) is sent.

  Here, when combining FSK symbols, the phase between the FSK symbols needs to be continuous in order to set PAPR to 0 dB. Therefore, the FSK signal generation unit 11 generates FSK symbols so that the phases between the FSK symbols are continuous.

  When the transmission signal combining unit 12 generates a transmission signal having a length N, it outputs this signal to the spreading unit 14. The spreading unit 14 spreads the transmission signal using the phase rotation sequence c (n) of length N generated by the phase rotation sequence generation unit 13. As the phase rotation sequence, for example, a chirp sequence as shown in the following equation (3) is used.

  In Expression (3), j is an imaginary unit, and a is a natural number. If the value of a is made different for each transmitter 1, a different spreading sequence is used for each transmitter 1, and the signal of each transmitter can be code division multiplexed. Note that the phase rotation sequence c (n) may be anything as long as the absolute value of each element is not zero (| c (n) | ≠ 0) and is constant regardless of n. Good.

  When the transmission signal of length N generated by the transmission signal combining unit 12 is s (n) and the phase rotation sequence is c (n), the spread signal x (n) output from the spreading unit 14 is (4)

As described above, in the present embodiment, a plurality of FSK symbols are collectively spread by one spreading sequence (phase rotation sequence c (n)). In a general system for spreading a transmission signal, spreading is performed for each symbol, whereas the transmitter 1 according to the present embodiment is characterized in that a plurality of symbols are spread together. Also in the transmitter 1 of this embodiment, it performs spreading for each symbol, i.e. it is considered a method of spreading the FSK symbol length N _i with spreading sequences of length N _i, in which case, less The following disadvantages occur.

- each transmitter 1 S (FSK number of symbols that binds), since the value of N _i (FSK symbol length) different, so that the use of spreading sequences of different sequence lengths for each transmitter 1. As a result, the orthogonality of the spreading sequence for each transmitter 1 is deteriorated, and the characteristics at the time of user multiplexing are deteriorated.
Although it has already been explained that spreading has the effect of increasing the confidentiality of the transmission signal and lowering the detectability, the effect is greater as the spreading sequence length is longer. For this reason, when spreading is performed for each symbol, the spreading sequence length becomes short, so these effects are reduced.

  From the above, in this embodiment, a plurality of symbols are collectively spread with a spreading sequence having a sequence length N.

  The signal after spreading (the output signal from the spreading unit 14) is output to the CP adding unit 15 where the CP is added (see FIG. 3).

  The signal to which the CP is added by the CP adding unit 15 is frequency-converted by the frequency converting unit 16 and input to the amplifier 17. The output of the amplifier 17 is input to the antenna 18, and a signal is transmitted from the antenna 18.

  Thus, in transmitter 1 of the present embodiment, a transmission signal is generated by combining a plurality of FSK symbols in the time direction. Therefore, even when a plurality of FSK symbols are transmitted per transmission block, a plurality of carriers do not overlap, and the PAPR can be set to 0 dB.

(Description of receiver)
FIG. 5 is a diagram illustrating a configuration example of the receiver 2 according to the present embodiment. As illustrated, the receiver 2 includes an antenna 21, a frequency conversion unit 22, a CP removal unit 23, a discrete Fourier transform unit 24, a frequency domain equalization unit 25, an inverse discrete Fourier transform unit 26, a phase rotation sequence generation unit 27, A despreading unit 28, a despread signal division unit 29, an FSK demodulation unit 30, and a parameter storage unit 31 are provided.

  The antenna 21 receives a signal transmitted from the transmitter 1. The CP removal unit 23 removes the CP from the signal received by the antenna 21. The discrete Fourier transform unit 24 converts the signal output from the CP removal unit 23 into a frequency domain signal. The frequency domain equalization unit 25 performs frequency domain equalization on the signal output from the discrete Fourier transform unit 24. The inverse discrete Fourier transform unit 26 converts the signal output from the frequency domain equalization unit 25 into a time domain signal. The phase rotation sequence generation unit 27 generates a phase rotation sequence described later. The despreading unit 28 despreads the signal output from the discrete Fourier transform unit 26 using the phase rotation sequence output from the phase rotation sequence generation unit 27. The despread signal dividing unit 29 divides the signal output from the despreading unit 28 into a plurality of FSK symbols (returns to the state before being combined by the transmitter 1). The FSK demodulator 30 performs FSK demodulation on the signal (FSK symbol) output from the despread signal divider 29. The parameter storage unit 31 stores parameters indicating the operating conditions of the despread signal division unit 29 and the FSK demodulation unit 30.

  In the signal reception operation in the receiver 2, the frequency converter 22 converts the signal received by the antenna 21 into a baseband signal. The output signal from the frequency converting unit 22 is input to the CP removing unit 23, and the CP removing unit 23 removes the CP from the input signal. The received baseband signal after CP removal is output as a reception block of length N.

  In the communication system according to the present embodiment, since the transmitter 1 adds a CP, frequency domain equalization can be performed in order to compensate for distortion in the propagation path. Therefore, the receiver 2 performs frequency domain equalization after CP removal. That is, the discrete Fourier transform unit 24 performs N-point DFT (or FFT) on the reception block of length N output from the CP removal unit 23 and converts it into a frequency domain signal. Thereafter, the frequency domain equalization unit 25 performs frequency domain equalization to compensate for distortion in the propagation path. Then, the inverse discrete Fourier transform unit 26 performs N-point IDFT (or IFFT) on the signal after the frequency domain equalization, and again converts the signal into a time domain signal.

The despreading unit 28 performs a despreading process corresponding to the spreading process performed by the transmitter 1. That is, the received signal is despread using the length N phase rotation sequence c ⁻¹ (n) generated by the phase rotation sequence generation unit 27. The phase rotation sequence generation unit 27 generates a sequence of the reciprocal number of the phase rotation sequence used in the spreading process of the transmitter 1 as c ⁻¹ (n). When the transmitter 1 performs the spreading process using the phase rotation sequence represented by the above equation (3), c ⁻¹ (n) generated by the phase rotation sequence generation unit 27 is expressed by the following equation (5). Is done.

Note that the receiver 2 receives signals from a plurality of transmitters 1, but c (n) is different for each transmitter 1, so the phase rotation sequence generation unit 27 responds to c (n) of each transmitter. C ⁻¹ (n) is generated.

When the received signal of length N input to the despreading unit 28 is y (n) and the phase rotation sequence is c ⁻¹ (n), the despread signal r (n) is expressed by the following equation (6). Is done.

  The r (n) obtained in this way is output from the despreading unit 28 and input to the despread signal dividing unit 29.

The despread signal division unit 29 divides the despread signal. The signal input from the despreading unit 28 is a combination of S FSK symbols as shown in FIG. That is, the signal is the same as the signal generated by the transmission signal combining unit 12 of the transmitter 1. The despread signal dividing unit 29 divides the signal input from the despreading unit 28 into S FSK symbols having lengths N _{1 to} N _S and sequentially outputs them to the FSK demodulating unit 30.

The FSK demodulator 30 demodulates input S FSK symbols. Here, the parameter storage unit 31 stores the same information as the parameter storage unit 19 of the transmitter 1. Values such as N, S, N _i , M _i (1 ≦ i ≦ S) required by the despread signal dividing unit 29 and the FSK demodulating unit 30 are input from the parameter storage unit 31.

Here, it supplements about the process which the FSK signal generation part 11 of the transmitter 1 and the FSK demodulation part 30 of the receiver 2 perform. As described above, when FSK symbols are combined in the time domain in the transmitter 1, it is necessary to make the phase between FSK symbols continuous in order to set PAPR to 0 dB. As a method for easily realizing this, there is a method using inverse discrete Fourier transform. FIG. 6 shows an FSK symbol creation operation by this method. Example shown in FIG. 6, the length N _i, a case of creating a FSK symbol modulation level M _i, to create the FSK symbol by IDFT (or IFFT) of N _i points. As shown, M _i out of N _i points are allocated for FSK symbol creation. Depending on the information data to be transmitted, any one of these M _i points is set to non-zero, and the other is set to 0, so that the signal after IDFT (or IFFT) has a M _i value of length N _i. FSK symbol. The method of using the M _i points of the N _i point and are predetermined between the transmitter and the receiver. When the FSK signal generation unit 11 of the transmitter 1 creates FSK symbols in this way, the first phase, the last, and the phase of each FSK symbol become 0, and therefore the phases between the FSK symbols are continuous.

Conversely the FSK demodulator 30 of the receiver 2, with respect to M _i value FSK signal length N _i, performs N _i point DFT (or FFT), performs demodulation.

  As described above, in the communication system according to the present embodiment, the transmitter 1 (transmitter provided in the communication device on the transmission side) has a plurality of FSK symbols and the phases of adjacent FSK symbols are continuous. Thus, the transmission signal having the length N obtained by combining in the time domain is spread by rotating the phase with the phase rotation sequence having the length N, and the CP is added for transmission. In addition, when the receiver 2 (the receiver included in the communication device on the receiving side) receives the signal from the transmitter 1, the receiver 2 removes the CP from the received signal and performs frequency domain equalization. The received signal is despread in the time domain using a reciprocal sequence of the phase rotation sequence used in the spreading process on the transmitter 1 side, and further, a plurality of combined FSK symbols are divided and demodulated It was decided to. This makes it possible to achieve both efficient frequency utilization and support for multiple transmission rates. In addition, the following effects can also be obtained.

  First, since a plurality of FSK symbols transmitted in one block are combined so that the phases are continuous in the time domain, the PAPR can be set to 0 dB. In addition, since the spreading process is performed by the spreading sequence having the same length as the combined signal (transmission block), it is possible to achieve confidentiality and detectability equivalent to the case of transmitting one FSK symbol. Further, since the spreading process is performed by the same spreading sequence (sequence length varies depending on the block length) regardless of the number of FSK symbols transmitted in one block, transmitters having different FSK symbol numbers or FSK symbol lengths per block These signals can be multiplexed.

Embodiment 2. FIG.
In this embodiment, a detailed description of the same operation as that described in the first embodiment is omitted, and a description will be given focusing on different parts. The configuration of the wireless communication system of the present embodiment is the same as that of the first embodiment (see FIG. 1).

(Description of transmitter)
FIG. 7 is a diagram illustrating a configuration example of a transmitter (referred to as a transmitter 1a) according to the second embodiment. As illustrated, the transmitter 1a is a modification of the transmitter 1 described in the first embodiment and includes a plurality of FSK signal generation units 11.

  In the transmitter 1 according to the first embodiment, FSK symbols are created one by one, and when the required number (S) is created, the FSK symbols are combined to perform spreading processing and subsequent processing. In transmitter 1a of the present embodiment, a plurality of FSK signal generation units 11 are used to create S FSK symbols in parallel. By doing so, the processing time required for transmission signal generation is made shorter than in the case of the first embodiment.

The transmitter 1 a includes S _max FSK signal generation units 11, and this S _max is the maximum value of the number S of FSK symbols in one transmission block assumed in the communication system. When transmitting a signal, the transmitter 1a first generates S FSK symbols in parallel using the S FSK signal generation units 11 among the S _max FSK signal generation units 11. The value of S (1 ≦ S ≦ S _max ) and which FSK signal generation unit 11 is used are instructed from the parameter storage unit 19. Each generated FSK symbol is input to transmission signal combining section 12. The transmission signal combining unit 12 combines the FSK symbols input from the S FSK signal generation units 11 to generate a transmission signal having a length N.

  Also in the present embodiment, the phases of the FSK symbols combined in the time domain need to be continuous. Therefore, each FSK signal generation unit 11 generates FSK symbols such that the phases of adjacent FSK symbols are continuous when combined by the transmission signal combining unit 12. If each FSK signal generation unit 11 uses the method of generating FSK symbols by IDFT (IFFT) as described in the first embodiment, the first and last phases of the generated FSK symbols become 0, It is possible to make the phase between each FSK symbol continuous.

  The operation of each unit after the diffusing unit 14 is as described in the first embodiment.

(Description of receiver)
FIG. 8 is a diagram illustrating a configuration example of a receiver (referred to as a receiver 2a) according to the second embodiment. As shown in the figure, the receiver 2a is a modification of the receiver 2 described in the first embodiment and includes a plurality of FSK demodulation units 30.

  In the receiver 2 of the first embodiment, one FSK demodulator 30 demodulates the S FSK symbols in one block one by one. However, in the receiver 2a of the present embodiment, a plurality of FSK symbols are demodulated. The FSK demodulation unit 30 is used to demodulate S FSK symbols in parallel. By doing so, the processing time required for demodulation is made shorter than in the case of the first embodiment.

The receiver 2a includes S _max FSK demodulation units 30. Note that S _max is the maximum value of the number of FSK symbols S in one transmission block assumed in the communication system, as already described. In the receiver 2a, when the despread signal is input to the despread signal division unit 29, the despread signal division unit 29 divides the reception block of length N into S original FSK symbols. Then, each FSK symbol is output to a different FSK demodulator 30. Then, each FSK demodulator 30 demodulates FSK symbols in parallel. The value of S (1 ≦ S ≦ S _max ) and which FSK symbol is demodulated by which FSK demodulator 30 are instructed from the parameter storage unit 31.

  As described above, in the communication system according to the present embodiment, the transmitter 1a includes a plurality of FSK signal generation units 11, and performs parallel generation processing of the FSK symbols that are collectively transmitted (transmitted as one block). It was decided. In addition, the receiver 2a includes a plurality of FSK demodulating units 30, and performs the demodulation processing of the FSK symbols transmitted in a batch in parallel. As a result, the same effects as those of the communication system of the first embodiment can be obtained, and the following effects can be obtained.

  In transmitter 1a, since a plurality of FSK symbols to be transmitted in one transmission block are created in parallel, the time required for generating each FSK symbol to be collectively transmitted may be shorter than that of transmitter 1 in the first embodiment. it can. Further, since the receiver 2a demodulates a plurality of FSK symbols in one reception block in parallel, the time required for demodulating each FSK symbol transmitted in a batch is shorter than that of the receiver 2 of the first embodiment. can do.

  In the present embodiment, the signal transmission / reception operation when the transmitter 1a and the receiver 2a are combined has been described. However, since the transmitted / received signal itself is the same regardless of the embodiment, the following is performed. Of course, a combination is also possible.

(1) Form in which receiver 2 (see FIG. 5) receives a signal transmitted by transmitter 1a (see FIG. 7) (2) Signal transmitted by transmitter 1 (see FIG. 2) is received by receiver 2a (FIG. 8) (See below)

  As described above, the transmitter according to the present invention is useful for a communication system to which a spread spectrum system is applied, and is particularly suitable for a transmitter that performs FSK as primary modulation.

DESCRIPTION OF SYMBOLS 1,1a Transmitter 2,2a Receiver 11 FSK signal generation part 12 Transmission signal coupling part 13, 27 Phase rotation sequence generation part 14 Spreading part 15 CP addition part 16, 22 Frequency conversion part 17 Amplifier 18, 21 Antenna 19, 31 Parameter storage unit 23 CP removal unit 24 Discrete Fourier transform unit 25 Frequency domain equalization unit 26 Inverse discrete Fourier transform unit 28 Despread unit 29 Despread signal division unit 30 FSK demodulator

Claims (7)

A transmitter corresponding to a spread spectrum modulation system that performs FSK modulation with primary modulation,
FSK signal generation means for performing FSK modulation on information data to generate FSK symbols;
Combining means for combining a plurality of FSK symbols in the time domain so that the phases of the respective FSK symbols are continuous to generate a transmission block;
Spreading means for spreading the transmission block using a phase rotation sequence;
A transmitter comprising: The transmitter according to claim 1, wherein the phase rotation sequence is a phase rotation sequence having the same length as the transmission block. The FSK signal generation means
A plurality of FSK symbol generation means for generating FSK symbols;
The number of FSK symbol generation means is the same as or more than the number of the plurality of FSK symbols, and the same number of FSK symbol generation means as that of the plurality of FSK symbols is used to parallelize the plurality of FSK symbols. The transmitter according to claim 1, wherein the transmitter is generated as follows. A receiver corresponding to a spread spectrum modulation system that performs FSK modulation by primary modulation,
The opposite transmitter performs a process reverse to the spreading process performed by the transmitter on the received signal, which is a signal obtained by combining a plurality of FSK symbols in the time domain and spread using a phase rotation sequence. Despreading means to diffuse;
Division means for dividing the signal after being despread by the despreading means into a plurality of FSK symbols;
Demodulation means for demodulating the plurality of FSK symbols;
A receiver comprising: The demodulating means includes
A plurality of FSK demodulation means for performing FSK demodulation processing on FSK symbols;
The number of the FSK demodulation means is equal to or greater than the number of the plurality of FSK symbols, and the same number of FSK demodulation means is used to demodulate the plurality of FSK symbols in parallel. The receiver according to claim 4, wherein A communication device on the signal transmission side includes the transmitter according to claim 1, 2, or 3,
A communication system comprising a receiver according to claim 4 or 5 on a signal receiving side communication device. It has multiple communication devices on the signal transmission side,
In each of the transmission side communication devices, the number of FSK symbols combined when generating the transmission block, and the value of the FSK symbol length determined individually with the signal reception side communication device; The communication system according to claim 6.

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