JP5737999B2 - Communication system, transmitter and receiver - Google Patents

Description

  The present invention relates to a communication system capable of multiplexing signals of a plurality of users.

  Conventional modulation systems used in communication systems include PSK (Phase Shift Keying), QAM (Quadrature Amplitude Modulation), APSK (Amplitude Phase Shift Keying), and FSK (Frequency Shift Keying). Among these, FSK has the following advantages.

  (A) In PSK, QAM, and APSK, since the peak power-to-average power ratio (PAPR) representing the ratio between the average power and the peak power of the signal is large, the influence of distortion due to the nonlinear amplifier is large. Therefore, there is a problem that the characteristics deteriorate. Therefore, it is necessary to make the PAPR of the signal as small as possible. On the other hand, in FSK, the PAPR can be set to 0 dB, and highly efficient communication can be performed.

  (B) In any modulation scheme, the number of transmission bits per symbol increases as the modulation level increases, and there is an advantage that the transmission rate can be increased. However, in PSK, QAM, and APSK, the sensitivity decreases as the modulation multi-level number increases. That is, there is a drawback that Eb / N0 that satisfies the required BER (Bit Error Ratio) increases. On the other hand, in FSK, the sensitivity is improved as the modulation multi-level number is increased. That is, Eb / N0 that satisfies the required BER decreases. Thus, in FSK, the two advantages of increasing the transmission rate and improving the sensitivity by increasing the modulation multi-level number can be enjoyed simultaneously.

  In the case of an M-value FSK with a modulation multi-level number of M, M carrier waves are used. Therefore, FSK has a problem that the frequency band per user increases as the modulation multi-level number increases, and the number of users that can be multiplexed in the frequency direction decreases accordingly. In order to make use of the advantage (b) of FSK, it is desirable that the modulation multi-level number is large. However, it is a problem that the number of multiple users is reduced, and other multiplexing methods must be considered.

  Here, there is a CDMA (Code Division Multiple Access) system as a technique for multiplexing a plurality of users who communicate at the same time and the same frequency (for example, Non-Patent Document 1 below). By using such a multiplexing method, a plurality of users communicate with each other at the same frequency. Therefore, it is considered that even if the number of multiplexed users is increased, the band does not widen and the above problem can be solved.

  Non-Patent Document 2 below discloses a technique for transmitting an FSK signal by spreading it with a phase rotation sequence.

Takeda Kazuaki, Adachi Fumiyuki "Error rate characteristics of DS-CDMA frequency domain equalization using pilot channel estimation" IEICE Technical Report, Radio Communication System RCS2004-86, pp.61-65, June 2004 Hiroyasu Sano, Noriyuki Fukui, Hiroshi Kubo “Examination of direct spread spectrum system that can despread and demodulate on frequency axis” 2009 IEICE Communication Society Conference, B-5-82

  However, according to the conventional CDMA technique, user multiplexing is performed using different spreading codes for each user, but a transmission signal is spread by a PN sequence or an M sequence. Therefore, the PAPR of the signal is increased, and there is a problem that the above advantage (a) cannot be utilized in the case of FSK.

  Further, according to the technique of Non-Patent Document 1, since the transmission signal is spread not by the PN sequence or the M sequence but by the phase rotation sequence, the PAPR does not increase due to the spreading, but performing user multiplexing has been studied. There was no problem.

  The present invention has been made in view of the above, and provides a communication system that can multiplex a plurality of users who generate modulated signals at the same frequency and can prevent an increase in PAPR of each user's signal. For the purpose.

  In order to solve the above-described problems and achieve the object, the present invention is a communication system including a plurality of transmitters and receivers, and the transmitter is a phase rotation sequence whose frequency changes with time. Transmitter parameter storage means for storing a parameter for determining a frequency change rate, phase rotation sequence generation means for generating a phase rotation sequence based on the parameter, a modulated signal multiplied by the phase rotation sequence, and a transmission signal A phase rotation sequence multiplying unit for obtaining each of the plurality of transmitters, wherein each transmitter parameter storage unit stores a parameter having a different value, and the receiver uses a parameter used by the plurality of transmitters. Receiver parameter storage means for storing, and phase rotation sequence reciprocal number generation means for generating a reciprocal number of the phase rotation sequence based on a parameter corresponding to a desired transmitter The multiplied by the reciprocal of the phase rotation sequence, characterized in that it comprises a phase rotation sequence reciprocal multiplying means for obtaining a signal from a desired transmitter to the receiver signal.

  According to the present invention, it is possible to multiplex a plurality of users who generate modulated signals with the same frequency, and it is possible to prevent an increase in the PAPR of each user's signal.

FIG. 1 is a diagram illustrating a configuration example of a wireless communication system. FIG. 2 is a diagram illustrating a configuration example of a transmitter. FIG. 3 is a diagram illustrating a carrier wave in the system band. FIG. 4 is a diagram illustrating an image in which the modulation signal is spread. FIG. 5 is a diagram showing the relationship between transmission data and CP. FIG. 6 is a diagram illustrating the frequency of the phase rotation series. FIG. 7 is a diagram illustrating the frequency of the phase rotation sequence when rate is negative. FIG. 8 is a diagram illustrating a configuration example of a receiver. FIG. 9 is a diagram illustrating a reception signal output from the inverse discrete Fourier transform unit. FIG. 10 is a diagram illustrating inverse discrete Fourier transform processing in the modulation unit of the transmitter. FIG. 11 is a diagram illustrating a discrete Fourier transform process in the demodulation unit of the receiver. FIG. 12 is a diagram illustrating a configuration example of a wireless communication system. FIG. 13 is a diagram illustrating a configuration example of a transmitter. FIG. 14 is a diagram illustrating the frequency of the phase rotation series. FIG. 15 is a diagram illustrating the frequency of the phase rotation sequence when rate = 4 and Novs = 4. FIG. 16 is a diagram illustrating a phase rotation sequence having a length of N / 4. FIG. 17 is a diagram illustrating a length N phase rotation sequence. FIG. 18 is a diagram illustrating a signal after multiplication by a phase rotation sequence when the lowest frequency carrier wave is used for modulation. FIG. 19 is a diagram showing a signal after phase rotation sequence multiplication in the case of using the highest frequency carrier wave in modulation. FIG. 20 is a diagram illustrating a signal after multiplication of the carrier wave in the system band and the phase rotation sequence. FIG. 21 is a diagram illustrating an example of a frequency change of the phase rotation series. FIG. 22 is a flowchart showing a phase rotation sequence generation process in the phase rotation sequence generation unit. FIG. 23 is a diagram illustrating a frequency when idx = p and step S104: No when rate> 0. FIG. 24 is a diagram illustrating the frequency of the phase rotation sequence when rate = 2 and 4. FIG. 25 is a diagram illustrating the frequency of the phase rotation sequence when rate = −2 as an example of rate <0. FIG. 26 is a diagram illustrating an example of a frequency change of a phase rotation sequence in which the phase and the frequency are always continuous. FIG. 27 is a flowchart illustrating the phase rotation sequence generation processing in the phase rotation sequence generation unit. FIG. 28 is a diagram showing the frequency of the phase rotation sequence when | rate | = 3, 4. FIG. 29 is a diagram illustrating the frequency of the phase rotation sequence when | rate | = 4. FIG. 30 is a diagram in which the frequency of the phase rotation series is changed in a sine wave shape. FIG. 31 is a diagram illustrating the frequency of the phase rotation sequence when Rate = 3 and 4. FIG. 32 is a diagram schematically showing a spectrum in which a frequency with a large power is repeatedly present. FIG. 33 is a diagram showing the frequency of the phase rotation sequence in the second embodiment. FIG. 34 is a diagram showing the frequency of the phase rotation series in the third embodiment. FIG. 35 is a diagram showing the frequency of the phase rotation sequence when | rate | is changed with rate> 0 in the phase rotation sequence of the second embodiment. FIG. 36 is a diagram illustrating the frequency of the phase rotation sequence when | rate | is changed in the phase rotation sequence of the third embodiment. FIG. 37 is a diagram showing a table when different users can use different positive and negative rates with the same absolute value as in the phase rotation sequences of the first and second embodiments. FIG. 38 is a diagram showing a table in the case where different positive and negative rates cannot be assigned to different users with the same absolute value as in the phase rotation sequences of the third and fourth embodiments.

  Embodiments of a communication system according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a wireless communication system according to the present embodiment. The wireless communication system includes transmitters 100-1, 100-2, 100-3,... And a receiver 200. In the following description, the transmitter may be referred to as a user. Specifically, each of the transmitter 100-m (m = 1, 2, 3,...) And the receiver 200 will be described. Note that although a wireless communication system is described in this embodiment, it can also be applied to wired communication.

  FIG. 2 is a diagram illustrating a configuration example of the transmitter 100-m according to the present embodiment. The transmitter 100-m includes a modulation unit 101, a phase rotation sequence generation unit 102, a chirp unit 103, a CP (Cyclic Prefix) addition unit 104, a frequency conversion unit 105, an amplifier 106, an antenna 107, parameters And a storage unit 108.

  First, in the transmitter 100-m, the modulation unit 101 generates a modulation signal s (n) having a length N corresponding to the information data. The modulation method to be used is not particularly limited, and any method such as FSK, PSK, QAM, and APSK may be used. Further, the modulation scheme and the modulation multi-level number may be the same or different for each user. FIG. 3 is a diagram illustrating a carrier wave in the system band. When there are a plurality of carriers in the system band as shown in FIG. 3 and M-value FSK is used as the modulation scheme, M carriers are assigned to the transmitter 100-m. When PSK, QAM, APSK or the like is used, one carrier wave is allocated. The transmitter 100-m generates a modulated signal using the allocated carrier wave. At this time, the allocated carrier wave may be different for each transmitter, or may be the same. In either case, signals of different users can be multiplexed by using the user multiplexing method of the present embodiment described later.

On the other hand, the phase rotation sequence generation unit 102 generates a phase rotation sequence c (n) using a parameter (rate described later) held in the parameter storage unit 108. The phase rotation sequence c (n) uses a sequence in which power is constant, that is, | c (n) | ² is constant regardless of n (0 ≦ n <N), and the frequency changes with time. Note that | x | means the absolute value of x.

  The chirp unit 103 is phase rotation sequence multiplication means, and multiplies the modulation signal s (n) by the phase rotation sequence c (n) as shown in the following equation (1) to obtain a transmission signal x (n).

  FIG. 4 is a diagram illustrating an image in which the modulation signal is spread. The modulation signal s (n) is a single carrier wave, but by multiplying the phase rotation sequence c (n) whose frequency changes with time, the modulation signal is also converted into a signal whose frequency changes with time. . As a result, the signal x (n) after multiplication by the phase rotation series c (n) becomes a signal spread over the entire band as shown in FIG.

  Next, CP adding section 104 adds a CP to the spread signal. FIG. 5 is a diagram showing the relationship between transmission data and CP. As shown in FIG. 5, a CP of length Ncp is added to the beginning of transmission data of length N. As the CP, a copy of the Ncp symbol after the transmission signal of length N is used. A signal of length N + Ncp created in this way is called a block.

  The frequency conversion unit 105 performs frequency conversion on the signal to which the CP is added by the CP addition unit 104, and the amplifier 106 amplifies the signal after frequency conversion. The antenna 107 receives the signal from the amplifier 106 and transmits the signal.

  Here, since the phase rotation series c (n) is a series with constant power, even if the modulation signal s (n) is multiplied by the phase rotation series c (n), the PAPR does not change. That is, it is possible to prevent a problem that the PAPR increases due to diffusion as in the CDMA system. In particular, when FSK is used for the modulation scheme, the PAPR of the transmission signal can be set to 0 dB.

  Next, a user multiplexing method will be described. If the speed of the frequency change of the phase rotation sequence c (n) is different for each user, the transmission signal x (n) after multiplication of the phase rotation sequence c (n) is also changed in frequency for each user. The speed can be different. By doing so, the signal of each user can be separated in the receiver 200. That is, in order to perform user multiplexing on transmission signals x (n) from a plurality of transmitters (users), a phase rotation sequence c (n) different for each user may be used.

  For example, consider using a phase rotation sequence c (n) such as the following equation (2). Equation (2) is an example, and any other phase rotation sequence c (n) may be used as long as the power is constant and the frequency changes with time.

  Here, j is an imaginary unit, N is a block length excluding CP, and is a sequence length of the phase rotation sequence. Further, rate is a parameter that determines the speed at which the frequency of the phase rotation series c (n) changes, and is held in the parameter storage unit 108. The larger | rate |, the faster the frequency of the phase rotation sequence c (n) changes. If the phase rotation sequence c (n) is created using a different rate for each user, it is possible to generate a phase rotation sequence c (n) different for each user. Therefore, the rate value is determined in advance between the transmitter 100-m and the receiver 200, and each transmitter 100-m holds the rate value used by the transmitter 100-m in the parameter storage unit 108.

  The rate is a real number satisfying 0 <| rate | <N. Although it may be a positive number or a negative number, it is desirable that the rate be an integer in order to reduce the interference between users when the receiver 200 separates each user's signal.

  FIG. 6 is a diagram showing the frequency f (n) of the phase rotation series c (n) shown in Expression (2). In FIG. 6, the horizontal axis represents time, the vertical axis represents frequency f (n), and an example in the case of rate = 2 and 3 is shown. When rate> 0, the frequency f (n) increases as n increases. However, when the frequency f (n) reaches 1 / 2Ts, the frequency returns to f (n) = − 1 / 2Ts and starts increasing again. Here, the transmission signal is a discrete time signal, and the time interval is Ts. At this time, according to the sampling theorem, the frequency f (n) can be expressed only between -1 / 2Ts and 1 / 2Ts. Therefore, such a folding of the frequency f (n) occurs.

  FIG. 7 is a diagram illustrating the frequency f (n) of the phase rotation series c (n) when rate is a negative number. As an example of the case where the rate is a negative number, a case where rate = −3 is shown. When rate <0, the frequency f (n) decreases as n increases. However, when f (n) reaches -1 / 2Ts, the frequency returns to f (n) = 1 / 2Ts and starts decreasing again.

  As described above, rate represents the rate of change of the frequency f (n). As shown in FIGS. 6 and 7, by changing n from 0 to N, the frequency f (n) of the phase rotation sequence c (n) is exactly the same. | Rate | In addition, it can be seen from FIG. 6 that the speed of change of the frequency f (n) is different when different rates are used. Therefore, if the rate is different, the phase rotation series c (n) is different. By assigning such different phase rotation series c (n) to each user, user multiplexing is possible.

  That is, the transmitters 100-1, 2, 3,... Multiply the different phase rotation sequences c (n) and transmit the transmission signal x (n), resulting in the transmitter 100-1, 2,..., It can be considered that a multiplexed signal in which a plurality of transmission signals x (n) are multiplexed is transmitted to the receiver 200. The receiver 200 can be regarded as receiving a multiplexed signal in which a plurality of transmission signals x (n) are multiplexed. As will be described later, in the receiver 200, when signals from a plurality of transmitters 100-1, 2, 3,... Are received, the phase rotation series c (n) multiplied by each signal is different. A signal from the desired transmitter can be obtained by using the phase rotation sequence c (n) multiplied by the desired transmitter.

  In the present embodiment, it is possible to multiplex users even if rates having the same absolute value but different signs are assigned to different users. For example, even if user A has rate = 3 and user B has rate = -3, these users can be multiplexed.

  Next, the operation of the receiver 200 will be described. FIG. 8 is a diagram illustrating a configuration example of the receiver 200 according to the present embodiment. Receiver 200 includes antenna 201, frequency conversion unit 202, CP removal unit 203, discrete Fourier transform unit 204, frequency domain equalization unit 205, inverse discrete Fourier transform unit 206, and phase rotation sequence reciprocal number generation unit. 207, a dechirp unit 208, a demodulation unit 209, and a parameter storage unit 210.

  A frequency conversion unit 202 converts a signal received by the antenna 201 into a baseband signal. The output of the frequency conversion unit 202 is input to the CP removal unit 203. CP removing section 203 removes the CP and obtains a reception block of length N.

  In this wireless communication system, since the transmitter 100-m adds a CP, frequency domain equalization can be performed to compensate for distortion in the propagation path. Therefore, the receiver 200 performs frequency domain equalization after CP removal. That is, the discrete Fourier transform unit 204 performs N-point DFT (Discrete Fourier Transform) (or FFT (Fast Fourier Transform)) on the reception block of length N output from the CP removal unit 203, and the frequency domain Convert to signal. Thereafter, the frequency domain equalization unit 205 performs frequency domain equalization to compensate for distortion in the propagation path. Then, the inverse discrete Fourier transform unit 206 performs N-point IDFT (Inverse Discrete Fourier Transform) (or IFFT (Inverse Fast Fourier Transform)), and again converts the signal into a time domain signal.

  The receiver 200 sequentially demodulates the signals of a plurality of users one by one. FIG. 9 is a diagram illustrating a received signal output from the discrete Fourier transform unit 204. Since each user transmits a signal at the same time and at the same frequency, the received signal is a combination of the signals of a plurality of users as shown in FIG. The receiver 200 needs to extract only one user's signal to be demodulated from these signals. The dechirp unit 208 performs the processing.

Each user's signal shown in FIG. 9 has a different frequency change rate. The dechirp unit 208 uses this fact to extract only the signal of the user who is trying to demodulate. First, the phase rotation sequence reciprocal number generation unit 207 generates a reciprocal sequence c ⁻¹ (n) of the user's phase rotation sequence c (n) to be demodulated. The phase rotation sequence reciprocal c ⁻¹ (n) is as shown in Equation (3).

The parameter storage unit 210 holds a rate value used by each user. The phase rotation sequence reciprocal number generation unit 207 selects the rate of the user who is trying to demodulate from among these, and generates a phase rotation sequence reciprocal number c ⁻¹ (n).

Then, dechirp unit 208 serving as phase rotation sequence reciprocal multiplication means multiplies the received signal by phase rotation sequence reciprocal c ⁻¹ (n), and outputs the result to demodulation unit 209. If the received signal input from the inverse discrete Fourier transform unit 206 is y (n) and the output to the demodulation unit 209 is r (n), the following equation (4) is calculated.

  This process corresponds to extracting only the component having the same frequency change rate as the phase rotation series c (n) from the received signal y (n). That is, only the signal of the user who has generated the transmission signal by the phase rotation sequence c (n) can be extracted by the transmitter 100-m.

  The demodulator 209 performs a demodulation process on the input signal.

  Here, it supplements about the modulation process of the modulation | alteration part 101 in the transmitter 100-m, and the demodulation process of the demodulation part 209 in the receiver 200. FIG. Various methods are conceivable as a method of generating a modulated signal in the transmitter 100-m, and one method using inverse discrete Fourier transform is conceivable as one method. FIG. 10 is a diagram illustrating an inverse discrete Fourier transform process in the modulation unit 101 of the transmitter 100-m. A modulation signal is generated by such an inverse discrete Fourier transform of N points.

  In the case of modulation by M value FSK, M points of N points are assigned to the user, and any one of the M points is set to a non-zero value according to data to be transmitted. Then, the remaining N-1 points are all set to 0 and inverse discrete Fourier transform is performed to generate a modulated signal.

  When modulation is performed using PSK, QAM, APSK, or the like, one point out of N points is assigned to the user. All other N-1 points are set to 0, and the allocated 1 point is set to a modulation symbol value. Then, inverse discrete Fourier transform is performed to generate a modulated signal.

  On the other hand, the demodulation unit 209 of the receiver 200 performs demodulation by discrete Fourier transform. FIG. 11 is a diagram illustrating a discrete Fourier transform process in the demodulation unit 209 of the receiver 200. An N-point discrete Fourier transform is performed on the output signal of length N from the dechirp unit 208.

  When the transmitter 100-m performs modulation using the M-value FSK, one point having the highest possibility of transmission is selected from the M points assigned to the user, and demodulation processing is performed. As a method for selecting one point, a method for selecting the largest real part or a method for selecting the largest power can be considered.

  When the transmitter 100-m performs modulation using PSK, QAM, APSK, or the like, demodulation processing is performed using the value of one point assigned to the user.

  In addition, the above description is a case where one receiver 200 receives different signals from the transmitter 100-m, which is a plurality of users, as shown in FIG. On the other hand, the user multiplexing method of the present embodiment can also be applied to the case where one transmitter transmits different signals to a plurality of receivers (users). FIG. 12 is a diagram illustrating a configuration example of a wireless communication system including one transmitter and a plurality of receivers (users). The wireless communication system includes a transmitter 300 and receivers 200-1, 200-2, 200-3,. In FIG. 12, a transmitter 300 multiplexes and transmits different signals to a plurality of users. In the case of this configuration, the receiver 200-k (k = 1, 2, 3,..., Nu) may be called a user.

  In this case, the transmitter 300 generates a transmission signal for each user and transmits it after multiplexing. FIG. 13 is a diagram illustrating a configuration example of the transmitter 300. A transmitter 300 that multiplexes signals for up to Nu users will be described. Transmitter 300 includes modulation sections 301-1 to Nu, phase rotation sequence generation sections 302-1 to Nu, chirp sections 303-1 to Nu, CP addition sections 304-1 to Nu, frequency conversion section 305, , An amplifier 306, an antenna 307, parameter storage units 308-1 to Nu, and a multiplexing unit 309.

  Compared with the configuration of transmitter 100-m in FIG. 2, in the configuration of transmitter 300 in FIG. 13, there are as many users (Nu) from the modulation unit to the CP addition unit, and signals for each user are generated individually. To do. At this time, since each user uses a different rate, each parameter storage unit 308-1 to Nu holds the value of the rate used by each user.

  The signals for each user are multiplexed by the multiplexing unit 309, and then transmitted from the antenna 307 via the frequency conversion unit 305 and the amplifier 306.

  On the other hand, the configuration of the receiver 200-k is the same as that in FIG. However, in the case of the wireless communication system of FIG. 1, the receiver 200 needs to sequentially demodulate the received data from the plurality of transmitters 100-m. For this purpose, the parameter storage unit 210 holds the rate values of all users. However, in the case of the wireless communication system of FIG. 12, the receiver 200-k only has to demodulate data directed to itself. Therefore, the parameter storage unit 210 of the receiver 200-k only needs to hold the rate value used by itself.

  In this way, even when a single transmitter 300 transmits different signals to the receivers 200-k, which are a plurality of users, by making the rate value different for each user, Multiplexing is possible.

  As described above, in the present embodiment, in the transmitter, the modulated signal is multiplied by the phase rotation sequence whose frequency changes with time, and each user's transmission signal becomes a signal whose frequency changes with time. By making the frequency change speed different for each user, it is possible to transmit each user's signal in a multiplexed state even when transmitting the signal of each user at the same time and at the same frequency. In the receiver, the desired signal can be obtained by multiplying the received signal by the reciprocal of the phase rotation sequence used in the desired transmitter. Thereby, in the communication system comprised of a transmitter and a receiver, it becomes possible to transmit / receive signals of each user at the same time and at the same frequency. Further, it is possible to prevent an increase in the PAPR of the signal, and in particular when using FSK, the PAPR can be set to 0 dB.

Embodiment 2. FIG.
In the present embodiment, the method for generating the phase rotation series c (n) is different from that in the first embodiment. Therefore, a method for generating the phase rotation sequence c (n) at the transmitter will be described below. Since the phase rotation sequence reciprocal c ^-1 (n) at the receiver is a reciprocal sequence of the phase rotation sequence c (n), it is possible to obtain “c ⁻¹ (n) = 1 / c (n)”. It is. Although one receiver shown in FIG. 1 will be described based on a system that receives different signals from a plurality of transmitters (users), as in the first embodiment, one transmitter shown in FIG. However, the present invention can also be applied to a system that transmits different signals to a plurality of receivers (users). A different part from Embodiment 1 is demonstrated.

  The phase rotation series c (n) described in the first embodiment has the following problems. Since the phase rotation sequence c (n) is a discrete signal and there is a limit to the frequency band that can be expressed by the sampling theorem as described above, the frequency f (n) at the frequency f (n) = 1 / 2Ts or −1 / 2Ts. Wrapping occurs. For example, when rate = 4, the frequency f (n) of the phase rotation series c (n) is as shown in FIG. FIG. 14 is a diagram illustrating the frequency f (n) of the phase rotation series c (n). This indicates a state in which oversampling is not performed, and the frequency f (n) is folded at the frequency f (n) = 1 / 2Ts.

  In general, a transmitter performs oversampling on a transmission signal. By oversampling the discrete signal of time interval Ts by Novs (> 1) times, it becomes a discrete signal of time interval Ts / Novs. At this time, the frequency band that can be expressed by the sampling theorem is expanded by Novs times. As a result, the return of the frequency f (n) does not occur when f (n) = 1 / 2Ts, and finally occurs at the frequency f (n) = 1 / 2Ts × Novs. FIG. 15 is a diagram illustrating the frequency f (n) of the phase rotation sequence c (n) when rate = 4 and Novs = 4. As a result, there is a problem that the band of the transmission signal is expanded to Novs times. Specifically, in FIG. 15, from “½Ts × 4 = 2Ts”, the return of the frequency f (n) occurs at 2Ts.

  Although it is possible to remove out-of-band power with a filter, there is a problem in that the time waveform of the signal changes greatly and the PAPR becomes large.

  Therefore, in the present embodiment, the phase rotation series c (n) is created so that the frequency f (n) is forcibly turned back on the mathematical formula without depending on the frequency band determined by the sampling theorem. That is, the phase rotation sequence generation unit 102 generates a phase rotation sequence c (n) that changes while taking a continuous value of the frequency f (n) within one period in which the frequency f (n) changes. Hereinafter, a method for generating such a phase rotation sequence c (n) will be described. This is only an example, and is a phase rotation sequence c (n) in which the power is constant and the frequency f (n) changes with time, and the frequency f (n) is forcibly turned back on the mathematical expression. As long as it is anything else.

  For the sake of simplicity, a case where rate = 4 and N is a multiple of 4 will be described as an example. FIG. 16 is a diagram illustrating a phase rotation sequence c (n) having a length of N / 4. FIG. 17 is a diagram illustrating a length N phase rotation sequence c (n). A phase rotation sequence c (n) of length N is created by connecting five phase rotation sequences c (n) of length N / 4 as shown in FIG. 16 as shown in FIG. However, the first and fifth dotted lines are not used.

The phase rotation series in FIG. 16 is denoted by c _ori (n), the phase is θ _ori (n), and the frequency is f _ori (n). At this time, the frequency f _ori (n) is expressed by equation (5) from FIG.

  Here, if the imaginary unit is j, the time interval of the discrete time signal is Ts, the phase of the phase rotation sequence c (n) is θ (n), each frequency is ω (n), and the frequency is f (n), Between these, the relationship of the following formula | equation (6) is formed.

From the equation (6), the phase θ _ori (n) is obtained by integrating the frequency f _ori (n) × 2πTs by n, and the phase rotation sequence c _ori (n) can be expressed using this. From the above, the phase rotation sequence c _ori (n) is expressed by the following equation (7).

A phase rotation sequence c (n) in FIG. 17 in which five phase rotation sequences _cori (n) are connected in the time direction is expressed by the following equation.

However, the phase θ ₁ (n) (−N / 8 ≦ n <0) and phase θ ₅ (n) (N ≦ n <9N / 8) portions indicated by dotted lines in FIG. 17 are not used.

Here, when the phase rotation series c _ori (n) are connected, the phase θ (n) is discontinuous at the joint, causing the spectrum to spread and the out-of-band power to increase. Therefore, in order to make the phase θ (n) continuous at the joint, the phase rotation series c (n) is created as follows. The frequency f (n) is the same as that in the equation (8).

  In this way, it is possible to create a phase rotation sequence c (n) in which the frequency f (n) changes between −1 / 2Ts and 1 / 2Ts regardless of whether oversampling is performed. However, the following problems arise.

  When the modulation signal is multiplied by the phase rotation series c (n), the frequency of the modulation signal changes in the range of 0 to 1/2 Ts on the high frequency side and 0 to 1/2 Ts on the low frequency side with the carrier wave as the center. FIG. 18 is a diagram illustrating a signal after multiplication by the phase rotation sequence c (n) when the lowest frequency carrier wave is used in the modulation. FIG. 19 is a diagram illustrating a signal after multiplication by the phase rotation sequence c (n) in the case of using the highest frequency carrier wave in the modulation. Compared to the first embodiment (see FIG. 4), the range in which the frequency of the signal changes depends on the carrier used. As a result, the signal after the phase rotation series c (n) multiplication spreads beyond the system band, which is a problem. That is, as shown in FIG. 9, the signals of the users cannot be superimposed on the same frequency band.

  Therefore, it is considered to use a phase rotation sequence c (n) whose frequency f (n) varies depending on the carrier used. FIG. 20 is a diagram illustrating a signal after multiplication of the carrier wave in the system band and the phase rotation sequence c (n). As shown in FIG. 20 (a), there are N carriers in the system band, and are indexed with # 0, # 1,. When modulating by PSK or QAM, one of N carriers is used, and the index number is i. When modulation is performed using M-value FSK, M of N carriers are used, and the index number of the middle carrier of the M carriers is i. A phase rotation sequence c (n) having a different frequency change range according to the value of i is used.

  In the phase rotation series c (n) so far, the frequency f (n) changes within the range of −1 / 2Ts to 1 / 2Ts, but “(((N−i) / N) −1”. ) · 1 / Ts to ((N−i) / N) · 1 / Ts ”is used. FIG. 21 is a diagram illustrating an example of a change in the frequency f (n) of the phase rotation series c (n) changing in such a range. Up to now, the frequency f (n) has been changed uniformly by 1/2 Ts on the high frequency side and the low frequency side, but in FIG. 21, the amount of change to the high frequency side is different from the amount of change to the low frequency side. Yes. As i increases, that is, as the frequency of the carrier wave used for modulation increases, the amount of change in the frequency f (n) of the phase rotation sequence c (n) to be used decreases toward the high frequency side and decreases toward the low frequency side. The amount of change increases. By using such a phase rotation sequence c (n), the signal after multiplication by the phase rotation sequence c (n) is as shown in FIG. become. That is, the range in which the frequency f (n) of the signal changes is the same regardless of the carrier used. As a result, the problem that the signal after multiplication by the phase rotation series c (n) spreads outside the system band is solved.

  Here, in the case of the M value FSK, it should be noted that the range in which the frequency f (n) of the phase rotation sequence c (n) changes is determined by the index number of the middle carrier among the M carriers. That is, the phase rotation sequence c (n) is not changed depending on which of the M carriers is used. If this is done, the receiving side cannot demodulate.

A phase rotation in which the frequency _fori (n) varies in the range of “(((N−i) / N) −1) · 1 / Ts to ((N−i) / N) · 1 / Ts”. Consider the case where rate = 4 as an example of how to create a sequence _cori (n). This phase rotation sequence c _ori frequency f _ori (n) changes (n) in the frequency axis direction in a range of -1 / 2Ts~1 / 2Ts "((N-i) / N ) · 1 / Ts It is shifted by “−1 / 2 · 1 / Ts”. Frequency f _ori of such phase rotation sequence c _ori (n) (n) the formula (5) f _ori (n) to the frequency axis direction "((N-i) / N ) · 1 / Ts- It can be obtained by shifting by “½ · 1 / Ts”. When the use of the relation of the formula (6), by integrating 2πTs × f _ori a (n) by n, the phase theta _ori (n) is obtained. As described above, the phase rotation in which the frequency f _ori (n) changes in the range of “(((N−i) / N) −1) · 1 / Ts to ((N−i) / N) · 1 / Ts”. The sequence _cori (n) can be expressed by the following equation (10).

  By connecting these in the time direction using Equation (9), a phase rotation sequence c (n) having a sequence length N is obtained.

  Here, the generation processing of the phase rotation sequence c (n) in the phase rotation sequence generation unit 102 will be described in general even when the rate is other than 4. FIG. 22 is a flowchart showing the process of generating the phase rotation sequence c (n) in the phase rotation sequence generation unit 102. N is the sequence length, and n is the number of sequences already created.

  First, the phase rotation sequence generation unit 102 initializes each variable to be used (step S101). Here, idx_ini is an initial value of idx, and 0 ≦ idx_ini <| N / rate |.

  Next, the phase rotation series production | generation part 102 calculates f and (theta) by the following formula | equation (11) (step S102).

  In the case of rate> 0, the equation (10) is generalized also in cases other than rate = 4, and n is replaced with idx. In the case of rate <0, an expression can be created in the same way as in the case of rate> 0, and the above expression is obtained.

  Next, the phase rotation series generation unit 102 adds θoff to the phase θ (step S103). This θoff is necessary to keep the phase θ always continuous.

  Next, the phase rotation series generation unit 102 checks whether the frequency f is in an appropriate range (step S104). That is, it is confirmed whether the following formula (12) is satisfied.

  When the frequency f is in an appropriate range (step S104: Yes), the phase rotation sequence generation unit 102 obtains the phase rotation sequence c (n) from the phase rotation sequence c (n) = exp (jθ). Then, the values of idx and n are updated to obtain the next phase θ and frequency f (step S105). When obtaining the phase rotation series c (n) without oversampling, Δ = 1. In the case of making by oversampling by Novs times, Δ = 1 / Novs.

  Next, when n <N is satisfied (step S106: Yes), the phase rotation series generation unit 102 thereafter repeats the processes from the above steps S101 to S105. If n <N is not satisfied (step S106: No), the process is terminated because the phase rotation sequence c (n) having the sequence length N is completed.

  In step S104, when the frequency f is not within the appropriate range (step S104: No), the phase rotation sequence generation unit 102 initializes idx to 0 and updates θoff to the value of the phase θ at that time. (Step S107). Then, the frequency f and the phase θ are created again.

  FIG. 23 is a diagram illustrating the frequency f (n) when rate> 0 and idx = p and Step S104: No. Since idx = p (*) becomes “f> (((N−1) / N) −1) · 1 / Ts”, idx = 0 is reset and the phase rotation sequence c (n) is continuously generated. To go. At this time, by setting the phase θ at idx = p (*) to θoff, the phase θ can be made continuous even after idx is reset.

  The above is how to create the phase rotation series c (n) in the present embodiment. In this case as well, user multiplexing is possible if the phase rotation sequence c (n) is generated at a different rate for each user as in the first embodiment. FIG. 24 is a diagram illustrating the frequency f (n) of the phase rotation sequence c (n) when rate = 2 and 4. In this way, if the rate is different, the speed of change of the frequency f (n) of the phase rotation sequence c (n) is different, so that user multiplexing is possible. FIG. 25 is a diagram illustrating the frequency f (n) of the phase rotation sequence c (n) in the case of rate = −2, as an example in the case of rate <0. Even when the frequency f (n) decreases as n increases, the phase θ can be continuous.

  In the present embodiment, as in the first embodiment, it is possible to multiplex users even if rates having the same absolute value but different positive and negative values are assigned to different users. For example, even if user A has rate = 3 and user B has rate = -3, these users can be multiplexed.

  As described above, in this embodiment, the phase of the phase rotation series is always continuous. Thereby, in addition to the effects of the first embodiment, it is possible to generate a transmission signal that does not widen the band even when oversampling is performed. In addition, the transmission signal band can be made the same regardless of the carrier wave used for modulation signal generation.

Embodiment 3 FIG.
In the present embodiment, the method for generating the phase rotation series c (n) is different from that in the second embodiment. Therefore, a method for generating the phase rotation sequence c (n) at the transmitter will be described below. A description will be given based on a system in which one receiver shown in FIG. 1 receives different signals from a plurality of transmitters (users), but a plurality of one transmitter shown in FIG. The present invention can also be applied to a system that transmits different signals to each receiver (user). A different part from Embodiment 2 is demonstrated.

  In the phase rotation sequence c (n) of the second embodiment, the phase θ (n) is always continuous, but the frequency f (n) is discontinuous at the turning point. That is, when rate> 0, the frequency f (n) is changed from “((N−i) / N) · 1 / Ts” to “(((N−i) / N) −1) · 1 / Ts”. When rate <0, the frequency f (n) is changed from “(((N−i) / N) −1) · 1 / Ts” to “((N−i) / N) · 1 / It changes to “Ts”. This causes the spectrum to broaden and out-of-band power to increase.

  Although it is possible to remove out-of-band power with a filter, there is a problem in that the time waveform of the signal changes greatly and the PAPR becomes large.

  Therefore, in the present embodiment, the phase rotation series c (n) is created so that not only the phase θ (n) but also the frequency f (n) is always continuous. That is, the phase rotation sequence generation unit 102 has a continuous value of the frequency f (n) and the phase θ (n) when the frequency f (n) of the phase rotation sequence c (n) changes over a plurality of periods. A phase rotation sequence c (n) that changes while taking is generated. Hereinafter, a method for generating such a phase rotation sequence c (n) will be described. This is an example, and the phase rotation sequence c (n) in which the power is constant and the frequency f (n) changes with time, and the phase θ (n) and the frequency f (n) of the sequence are always continuous. As long as it is, it may be anything else.

  FIG. 26 is a diagram illustrating an example of a frequency change of the phase rotation sequence c (n) in which the phase θ (n) and the frequency f (n) are always continuous. This is an example in which the frequency f (n) is rotated four times during the sequence length N, and the frequency f (n) repeats increasing and decreasing. By doing so, the frequency f (n) is always continuous. Such a phase rotation sequence c (n) can be realized by switching the rate between positive and negative every time the frequency f (n) makes one round.

In the present embodiment, as in the second embodiment, the phase rotation series c _ori (n) is connected in the time direction to generate the phase rotation series c (n). FIG. 27 is a flowchart for obtaining phase rotation sequence c (n) in phase rotation sequence generation section 102 in the present embodiment. The processing from step S201 to S206 is the same as that from step S101 to S106 in the second embodiment (see FIG. 22), and the only difference is that the processing of the following equation (13) is increased in step S207.

  As a result, the rate is switched between positive and negative for each round (| rate | does not change), and the frequency f (n) of the phase rotation series c (n) repeats increasing / decreasing.

  The above is how to create the phase rotation series c (n) in the present embodiment. In this way, since each user switches between using positive and negative rates, in Embodiments 1 and 2, it was possible to assign different users with different absolute values but different positive and negative values. Note that this is not possible in this embodiment. For example, in Embodiments 1 and 2, multiplexing was possible by setting user A to rate = 3 and user B to rate = -3. However, in this embodiment, since each user switches between using positive and negative rates, both users A and B use both 3 and -3 as rates. Therefore, such multiplexing cannot be performed. In this embodiment, it is necessary to ensure that | rate | of different users is different.

  In the present embodiment, user multiplexing is possible if the phase rotation sequence c (n) is generated by | rate | which differs for each user. FIG. 28 is a diagram illustrating the frequency f (n) of the phase rotation series c (n) when | rate | = 3, 4. Thus, if | rate | is different, the speed of change of the frequency f (n) of the phase rotation series c (n) is different, and thus user multiplexing is possible. In the present embodiment, the frequency f (n) of the phase rotation series c (n) repeatedly increases and decreases, but it is of course possible to start from the decrease. FIG. 29 is a diagram illustrating the frequency f (n) of the phase rotation series c (n) when | rate | = 4. Thus, even when starting from a decrease, the same effect as when starting from an increase can be obtained by performing an operation in which the positive and negative rates are switched every round.

  As described above, in the present embodiment, the frequency of the phase rotation series is always continuous. Thereby, in addition to the effects of the second embodiment, it is possible to suppress further expansion of the band and further reduce the out-of-band power.

Embodiment 4 FIG.
In the present embodiment, the method for generating the phase rotation series c (n) is different from that in the third embodiment. Therefore, a method for generating the phase rotation sequence c (n) at the transmitter will be described below. A description will be given based on a system in which one receiver shown in FIG. 1 receives different signals from a plurality of transmitters (users), but a plurality of one transmitter shown in FIG. The present invention can also be applied to a system that transmits different signals to each receiver (user). A different part from Embodiment 3 is demonstrated.

  By creating the phase rotation series c (n) as in the third embodiment, the frequency f (n) and the phase θ (n) are always continuous. However, the speed at which the frequency f (n) changes abruptly at the point where the frequency f (n) switches from increasing to decreasing or switching from decreasing to increasing. This causes an increase in spectrum out-of-band power.

  Although it is possible to remove out-of-band power with a filter, there is a problem in that the time waveform of the signal changes greatly and the PAPR becomes large.

  Therefore, in the present embodiment, a method for changing the frequency f (n) more smoothly will be described. Specifically, the frequency f (n) is changed in a sine wave shape. The phase rotation sequence generation unit 102 generates a phase rotation sequence c (n) in which the frequency f (n) changes in a sine wave shape. Hereinafter, a method for generating such a phase rotation sequence c (n) will be described. This is only an example, and it is a phase rotation sequence c (n) in which the power is constant and the frequency f (n) changes with time, and the frequency f (n) of the sequence changes sinusoidally. As long as it is anything else. FIG. 30 is a diagram in which the frequency f (n) of the phase rotation series c (n) is changed in a sine wave shape.

  The frequency f (n) of such a phase rotation series c (n) is expressed by the following equation (14).

  FIG. 30 shows an example when rate = 4 and α = 0. Here, α is a constant that does not depend on other variables, and by changing this value, the value of the frequency f (n) at the time of n = 0 can be changed.

  From equation (6), 2πTs × f (n) is integrated by n, thereby obtaining the phase θ (n) of the following equation (15), and the phase rotation sequence c (n) can be obtained.

What is necessary is just to produce the phase rotation series c (n) of this Embodiment according to Formula (15). As in the second and third embodiments, it is not necessary to connect the phase rotation series c _ori (n) in the time direction to create the phase rotation series c (n), and 0 ≦ n < The phase rotation series c (n) can be generated by simply substituting n of N in order. The phase θ (n) and the frequency f (n) of the phase rotation series c (n) created in this way are always continuous, and the frequency f (n) always changes smoothly.

  However, in the present embodiment, when the frequency θ (n) is calculated by Equation (15) with two rates having the same absolute value but different positive and negative values, the two values are the same. Therefore, in the present embodiment, as in the third embodiment, it is not possible to assign and multiplex rates having the same absolute value but different positive and negative values. For example, in Embodiments 1 and 2, multiplexing was possible by setting user A to rate = 3 and user B to rate = -3. However, in the present embodiment, c (n) generated with rate = 3 and c (n) generated with rate = -3 are exactly the same phase rotation sequence, and thus such multiplexing cannot be performed. In this embodiment, it is necessary to ensure that | rate | of different users is different.

  The above is how to create the phase rotation series c (n) in the present embodiment. In this case as well, user multiplexing is possible if the phase rotation sequence c (n) is generated at a different rate for each user. FIG. 31 is a diagram showing the frequency f (n) of the phase rotation series c (n) when | Rate | = 3, 4. Thus, if the rate is different, the rate of change of the frequency f (n) of the phase rotation sequence c (n) is different, and thus user multiplexing is possible as in the previous embodiments.

  As described above, in the present embodiment, the frequency change of the phase rotation sequence is further smoothed. Thereby, in addition to the effects of the third embodiment, it is possible to suppress further expansion of the band and further reduce the out-of-band power.

Embodiment 5 FIG.
In the present embodiment, the method of generating the phase rotation series c (n) is different from the other embodiments. Therefore, a method for generating the phase rotation sequence c (n) at the transmitter will be described below. A description will be given based on a system in which one receiver shown in FIG. 1 receives different signals from a plurality of transmitters (users), but a plurality of one transmitter shown in FIG. The present invention can also be applied to a system that transmits different signals to each receiver (user). A different part from Embodiment 1-4 is demonstrated.

  When a transmission signal is created by the phase rotation sequence c (n) of Embodiments 1 to 4, the power in the band is not constant, and a phenomenon in which a frequency with high power is repeatedly present occurs. FIG. 32 is a diagram schematically showing a spectrum in which a frequency with a large power is repeatedly present.

  In Embodiments 1 to 4, the value of | rate | is always constant for each user. Therefore, it can be said that the frequency f (n) of these phase rotation series c (n) has periodicity. FIG. 33 is a diagram showing the frequency f (n) of the phase rotation series c (n) in the second embodiment. FIG. 34 is a diagram showing the frequency f (n) of the phase rotation series c (n) in the third embodiment. In FIG. 33, it can be seen that the frequency f (n) of the phase rotation series c (n) repeats the same pattern every cycle, and in FIG. It is considered that this periodicity appears in the frequency spectrum in the form of “frequency with high power”.

  As a result of this phenomenon, there is a problem that detectability increases. High detectability means that there is a high possibility that a person other than the receiver will be communicating. When it is necessary to be unaware of the others, it is necessary to take measures to reduce the detectability by making the in-band power constant.

  Therefore, in the present embodiment, a method of generating a phase rotation sequence c (n) that makes the in-band power constant and reduces the detectability will be described. Since this periodicity occurs because | rate | is constant for each user, it is considered that | rate | may be changed. That is, every time the frequency f (n) of the phase rotation series c (n) makes Nrate (≧ 1) rounds, the rate is changed in the range of 0 <MINrate ≦ | rate | ≦ MAXrate. The phase rotation sequence generation unit 102 generates the phase rotation sequence c (n) by changing the rate for each Nrate period in which the frequency f (n) changes. Here, MINrate is the minimum value of | rate |, and MAXrate is the maximum value of | rate |.

  An example in which the value of | rate | is changed every time the frequency f (n) makes one round is shown in FIGS. FIG. 35 is a diagram illustrating the frequency f (n) of the phase rotation sequence c (n) in the case where | rate | is changed with rate> 0 in the phase rotation sequence c (n) of the second embodiment. . FIG. 36 is a diagram showing the frequency f (n) of the phase rotation sequence c (n) when | rate | is changed in the phase rotation sequence c (n) of the third embodiment. Since the value of | rate | changes, the slope of the graph of the frequency f (n) changes every time.

  As a method of changing the value of | rate |, it may be changed randomly or a method of changing it regularly according to a fixed rule (for example, increasing it by a fixed value). However, when the phase rotation sequence c (n) of the third embodiment is used, it is necessary to switch between the positive and negative rates every time the frequency f (n) makes one round. In addition, when the phase rotation sequence of the first and second embodiments is used c (n), it is necessary to always keep the positive and negative of the rate constant. When the phase rotation sequence c (n) of the fourth embodiment is used, the generated phase rotation sequence c (n) is the same if the absolute value is the same regardless of whether the rate is positive or negative. Therefore, there is no particular restriction on the positive / negative of the rate.

  For example, when | rate | is changed from 2 → 10 → 7 → 13 → 3 →..., The value of rate changes as follows.

When using the phase rotation sequence c (n) of the first and second embodiments,
2 → 10 → 7 → 13 → 3 →…
Or
-2 → -10 → -7 → -13 → -3 → ...

When using the phase rotation sequence c (n) of the third embodiment,
2 → -10 → 7 → -13 → 3 →…
Or -2 → 10 → -7 → 13 → -3 → ...

When using the phase rotation sequence c (n) of the fourth embodiment,
2 → 10 → 7 → 13 → 3 →…

  Further, the smaller the value of Nrate (≧ 1), the greater the frequency with which the value of | rate | changes, and the periodicity of the frequency f (n) of the phase rotation sequence c (n) decreases. That is, it is considered that a smaller value of Nrate is better for reducing the detectability while keeping the in-band power constant.

  Next, a case where user multiplexing is performed will be described. Note that the MINrate, MAXrate, and Nrate values may be different for each user or the same. Similar to other embodiments, different users cannot use the same rate. Therefore, it is necessary for each user to change the value of the rate and prevent different users from using the same rate.

  Therefore, when Nu users are multiplexed, the rate in the range of 0 <MINrate ≦ | rate | ≦ MAXrate is divided into Nu groups, and each group is assigned to each user. The user generates the phase rotation sequence c (n) using only the rate in the assigned group. Thereby, different users can always use different rates.

  37 and 38 show an example in which MINrate = 5, MAXrate = 20, Nu = 4 and only an integer is used as the rate. FIG. 37 is a diagram showing a table when different users can use different positive and negative rates with the same absolute value as in the phase rotation series c (n) of the first and second embodiments. FIG. 38 is a diagram showing a table in the case where different positive and negative rates cannot be assigned to different users, as in the phase rotation sequences c (n) of the third and fourth embodiments. It shows the rate corresponding to each group and the assignment to the user. In both cases, the rate is divided into Nu (= 4) groups, and each group is assigned to a different user. Each user selects and uses the rate value each time the frequency f (n) of the phase rotation sequence c (n) makes Nrate rounds from the group assigned to the user. In this way, different users can be prevented from using the same rate.

  Specifically, in transmitter 100-m (or transmitter 300), when a plurality of rates are grouped and a group is assigned to each parameter storage unit 108 (or parameter storage unit 308-1 to Nu), The phase rotation sequence generation unit 102 (or the phase rotation sequence generation unit 302-1 to Nu) uses the rate selected from the group assigned to the parameter storage unit connected to itself to generate the phase rotation sequence c (n). Generate.

  As described above, in the present embodiment, the rate of the phase rotation sequence is changed every time the frequency makes Nrate rounds. Thereby, in addition to the effects in the first to fourth embodiments, it is possible to make the in-band power of the frequency spectrum constant and reduce the detectability.

100-1, 100-2, 100-3, 300 Transmitter 101, 301-1 to Nu modulation unit 102, 302-1 to Nu phase rotation sequence generation unit 103, 303-1 to Nu chirp unit 104, 304-1 ~ Nu CP adding section 105, 305 Frequency conversion section 106, 306 Amplifier 107, 307 Antenna 108, 308-1 ~ Nu Parameter storage section 200, 200-1, 200-2, 200-3 Receiver 201 Antenna 202 Frequency conversion section 203 CP removal unit 204 Discrete Fourier transform unit 205 Frequency domain equalization unit 206 Inverse discrete Fourier transform unit 207 Phase rotation sequence inverse number generation unit 208 Dechirp unit 209 Demodulation unit 210 Parameter storage unit 309 Multiplexing unit

Claims (10)

A communication system comprising a plurality of transmitters and receivers,
The transmitter is
Transmitter parameter storage means for storing parameters for determining the frequency change rate of the phase rotation sequence whose frequency changes with time;
Based on the above parameters, within one period when the frequency changes, the frequency changes while taking a continuous value, when it reaches the upper limit frequency, it changes to the lower limit frequency, or when it reaches the lower limit frequency Phase rotation sequence generation means for generating a phase rotation sequence that changes to an upper limit frequency ;
Phase rotation sequence multiplication means for multiplying the modulation signal by the phase rotation sequence to obtain a transmission signal;
In each of the plurality of transmitters, each transmitter parameter storage unit stores a parameter having a different value, and each phase rotation sequence generation unit generates a phase rotation sequence having a different frequency change rate for each transmitter. ,
The receiver
Receiver parameter storage means for storing parameters used in the plurality of transmitters;
Phase rotation sequence reciprocal number generating means for generating a reciprocal number of the phase rotation sequence based on a parameter corresponding to a desired transmitter;
A phase rotation sequence reciprocal multiplication means for multiplying the received signal by the reciprocal of the phase rotation sequence to obtain a signal from a desired transmitter;
A communication system comprising: A communication system comprising a transmitter and a plurality of receivers,
The transmitter is
Transmitter parameter storage means for storing parameters for determining the frequency change rate of the phase rotation sequence whose frequency changes with time;
Based on the above parameters, within one period when the frequency changes, the frequency changes while taking a continuous value, when it reaches the upper limit frequency, it changes to the lower limit frequency, or when it reaches the lower limit frequency Phase rotation sequence generation means for generating a phase rotation sequence that changes to an upper limit frequency ;
Phase rotation sequence multiplication means for multiplying the modulation signal by the phase rotation sequence to obtain a transmission signal;
For each of the receivers, each transmitter parameter storage means stores a parameter having a different value, and each phase rotation sequence generation means generates a phase rotation sequence having a different frequency change rate for each receiver. ,
Furthermore, multiplexing means for multiplexing the transmission signal input from each phase rotation series multiplication means,
With
The receiver
Receiver parameter storage means for storing parameters corresponding to itself;
A phase rotation sequence reciprocal number generating means for generating a reciprocal number of the phase rotation sequence based on a parameter corresponding to itself;
Multiplying the received signal by the reciprocal of the phase rotation sequence to obtain a signal addressed to itself;
Each receiver parameter storage means of the plurality of receivers stores parameters having different values.
A communication system characterized by the above. The phase rotation sequence generation means includes
When a system band is composed of a plurality of carriers, a phase rotation sequence in which the frequency changing range is changed is generated based on the position of the carrier wave used for generating the modulation signal in the system band.
Communication system according to claim 1 or 2, characterized in that. The phase rotation sequence generation means includes
Changing the parameter for each predetermined period in which the frequency changes to generate a phase rotation sequence;
The communication system according to claim 1 , 2 or 3 . The transmitter in a communication system composed of a plurality of transmitters and receivers,
Transmitter parameter storage means for storing parameters for determining the frequency change rate of the phase rotation sequence whose frequency changes with time;
Based on the above parameters, within one period when the frequency changes, the frequency changes while taking a continuous value, when it reaches the upper limit frequency, it changes to the lower limit frequency, or when it reaches the lower limit frequency Phase rotation sequence generation means for generating a phase rotation sequence that changes to an upper limit frequency ;
Phase rotation sequence multiplication means for multiplying the modulation signal by the phase rotation sequence to obtain a transmission signal;
In each of the plurality of transmitters, each transmitter parameter storage unit stores a parameter having a different value, and each phase rotation sequence generation unit generates a phase rotation sequence having a different frequency change rate for each transmitter. A transmitter characterized by that. The transmitter in a communication system composed of a transmitter and a plurality of receivers,
Transmitter parameter storage means for storing parameters for determining the frequency change rate of the phase rotation sequence whose frequency changes with time;
Based on the above parameters, within one period when the frequency changes, the frequency changes while taking a continuous value, when it reaches the upper limit frequency, it changes to the lower limit frequency, or when it reaches the lower limit frequency Phase rotation sequence generation means for generating a phase rotation sequence that changes to an upper limit frequency ;
Phase rotation sequence multiplication means for multiplying the modulation signal by the phase rotation sequence to obtain a transmission signal;
For each of the receivers, each transmitter parameter storage means stores a parameter having a different value, and each phase rotation sequence generation means generates a phase rotation sequence having a different frequency change rate for each receiver. ,
Furthermore, multiplexing means for multiplexing the transmission signal input from each phase rotation series multiplication means,
A transmitter comprising: The phase rotation sequence generation means includes
When a system band is composed of a plurality of carriers, a phase rotation sequence in which the frequency changing range is changed is generated based on the position of the carrier wave used for generating the modulation signal in the system band.
The transmitter according to claim 5 or 6 , wherein The phase rotation sequence generation means includes
Changing the parameter for each predetermined period in which the frequency changes to generate a phase rotation sequence;
The transmitter according to claim 5, 6 or 7 . A receiver in a communication system comprising a plurality of transmitters and receivers,
A parameter for determining the frequency change rate of the phase rotation sequence which varies in frequency with time, the plurality of transmitters the Ri frequency change rate Do different for each transmitter in, within one period of the frequency changes, the frequency changed while taking sequential values, used to generate the phase rotation sequence you change the frequency of the upper limit when when it reaches the upper limit frequency changes the frequency of the lower limit, or has reached the frequency of the lower limit Receiver parameter storage means for storing parameters;
Phase rotation sequence reciprocal number generating means for generating a reciprocal number of the phase rotation sequence based on a parameter corresponding to a desired transmitter;
A phase rotation sequence reciprocal multiplication means for multiplying the received signal by the reciprocal of the phase rotation sequence to obtain a signal from a desired transmitter;
A receiver comprising: A receiver in a communication system comprising a transmitter and a plurality of receivers,
A parameter for determining the frequency change rate of the phase rotation sequence to the frequency change with time, the transmitter the frequencies change rate Ri Do different for each receiver in, within one period of frequency changes, the frequency is continuously It varies while taking a value of parameters used when the time has been reached the upper limit frequency changes the frequency of the lower limit, or has reached the frequency of the lower limit for generating a phase rotation sequence you change the frequency of the upper limit Receiver parameter storage means for storing parameters corresponding to itself,
A phase rotation sequence reciprocal number generating means for generating a reciprocal number of the phase rotation sequence based on a parameter corresponding to itself;
Multiplying the received signal by the reciprocal of the phase rotation sequence to obtain a signal addressed to itself;
And each receiver parameter storage means of the plurality of receivers stores parameters having different values.

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