JP5127647B2 - Receiving apparatus and demodulation method - Google Patents

Description

  The present invention relates to a receiving apparatus and a demodulation method for demodulating a digital radio modulated signal.

  In general, a receiving apparatus in a wireless communication system performs demodulation by using system parameters (encoding, modulation scheme, etc.) predetermined in the system as known information and mounting a corresponding demodulator based on the known information.

  On the other hand, for example, as described in Patent Document 1 below, a plurality of means for demodulating corresponding to the range of system parameters (hereinafter referred to as transmission parameters) used for transmission assumed by the receiving apparatus are provided in advance. In addition, there is a receiving apparatus that estimates a transmission parameter based on a received signal for a signal whose transmission parameter is unknown, and performs demodulation by selecting a demodulator corresponding to the estimated transmission parameter. Hereinafter, a conventional technique for estimating and demodulating the transmission parameter based on the received signal will be described.

  In such a conventional technique, for example, a digital communication receiving apparatus that receives and demodulates a digital radio modulated communication signal includes a plurality of demodulators corresponding to each of a plurality of types of modulation schemes assumed, Modulation method recognition means for recognizing the modulation method, and demodulator selection means for selecting a demodulator corresponding to the recognition result from a plurality of demodulators based on the recognition result by the modulation method recognition means. With such a configuration, even when the modulation method of the received communication signal is unknown, this can be automatically recognized, and a demodulator that demodulates the received signal corresponding to the recognition result can be selected. A receiving device is obtained.

JP-A-5-218914

  However, according to the above conventional technique, the general-purpose receiver or the communication waveform analyzer includes a plurality of demodulators corresponding to the respective modulation schemes, and the demodulator of the modulation schemes based on the recognition result of the modulation scheme recognition means. By selecting the corresponding demodulator from among them, even when the modulation scheme of the received communication signal is unknown, the modulation scheme of the received signal can be recognized and demodulated. For this reason, it is necessary to provide a different demodulator for each different modulation scheme, and there is a problem that the circuit scale increases when the range of the modulation scheme to be considered in configuring the receiving apparatus is expanded.

  The present invention has been made in view of the above, and is a receiver that can automatically determine a demodulation method according to a modulation method and a transmission state, and can deal with a wide range of modulation methods without increasing the circuit scale. And to obtain a demodulation method.

In order to solve the above-described problems and achieve the object, the present invention estimates first transmission path information based on a received signal, transmits a transmission parameter including information on a modulation scheme, the received signal, and the first Transmission path estimation type maximum likelihood sequence estimation demodulation that performs maximum likelihood sequence estimation by the Viterbi algorithm based on transmission path information and calculates first reliability information that is an evaluation index of reception quality based on the maximum likelihood sequence estimation result Means and preliminarily holding second transmission path information determined based on a sequence candidate in the Viterbi algorithm, and performing maximum likelihood sequence estimation based on the transmission parameter, the received signal, and the second transmission path information, Transmission path information holding type maximum likelihood sequence estimation demodulating means for calculating the second reliability information based on the maximum likelihood sequence estimation result, the transmission parameter instruction, And a control means for controlling the non-operation, the demodulation method of selecting the first reliability information as the most reliable previous Symbol demodulator hand stage that corresponds to the information of the reliability of the second reliability information Selection means, and the control means determines the transmission parameter based on the demodulation means selected by the demodulation method selection means, and determines the determined transmission parameter for the demodulation means selected by the demodulation method selection means. Te Instruct, characterized in that for operating the demodulating means.

  According to the present invention, a transmission path estimation type maximum likelihood sequence estimation demodulator that estimates transmission path information based on a received signal and performs maximum likelihood sequence estimation based on a Viterbi algorithm, and a transmission path determined by a sequence candidate in the Viterbi algorithm Maximum likelihood sequence estimation is performed by two demodulators: a transmission path information holding type maximum likelihood sequence estimation demodulator that holds information in advance and performs maximum likelihood sequence estimation based on the transmission path information, and has high reliability. Demodulation is performed using the demodulator from which the degree information has been obtained, so that it is possible to automatically determine the modulation method and the demodulation method according to the transmission state, and to expand to a wide range of modulation methods without increasing the circuit scale. The effect that it can respond is produced.

  Embodiments of a receiving apparatus 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.
1 is a diagram illustrating a functional configuration example of a first embodiment of a receiving device according to the present invention. As shown in FIG. 1, the receiving apparatus according to the present embodiment includes a receiving antenna 1 for receiving radio waves, and downsampling and A / D (Analog to Digital) with respect to an analog received signal received by the receiving antenna 1. A high-frequency unit 2 for performing conversion and converting into a digital complex baseband received signal, a received signal memory 3 for storing the digital complex baseband received signal, a switch 4 for selecting a demodulator at the subsequent stage, and a digital complex baseband A transmission path estimation type maximum likelihood sequence estimation demodulator 5 that estimates transmission path information based on a received signal and performs maximum likelihood sequence estimation based on a Viterbi algorithm, and transmission path information determined by a Viterbi algorithm sequence candidate are stored in advance. A transmission path information holding type maximum likelihood sequence estimation demodulator 6 that performs maximum likelihood sequence estimation based on the transmission path information, and a transmission path estimation type Demodulation method selection for selecting a demodulation method by selecting a reliable one from reliability information that is an evaluation index of reception quality output from the likelihood sequence estimation demodulator 5 and the transmission channel information holding type maximum likelihood sequence estimation demodulator 6 And a demodulator control unit 8 for controlling the execution and operation parameters (including transmission parameters) of the transmission channel estimation type maximum likelihood sequence estimation demodulator 5 and the transmission channel information holding type maximum likelihood sequence estimation demodulator 6. I have.

  FIG. 2 is a diagram illustrating a configuration example of the transmission path estimation type maximum likelihood sequence estimation demodulator 5 of the present embodiment. As shown in FIG. 2, the transmission path estimation type maximum likelihood sequence estimation demodulator 5 of this embodiment includes a branch metric generation section 21 that generates a branch metric for each state based on the Viterbi algorithm based on the transmission path estimation result, An ACS (Add Compare Select) unit 22 that selects a surviving path of the Viterbi algorithm, a transmission path estimating unit 23 that performs transmission path estimation based on the received signal and the surviving path selection result, and update of the path memory for each state based on the Viterbi algorithm A path memory update unit 24 for holding, a path metric update unit 25 for updating / holding a path metric for each state based on the Viterbi algorithm, and a decoding result based on the path memory held in the path memory update unit 24 And a decoded data output unit 26 for determining and outputting the data.

  FIG. 3 is a diagram illustrating a configuration example of the transmission path information holding maximum likelihood sequence estimation demodulator 6 according to the present embodiment. As shown in FIG. 3, the transmission line information holding type maximum likelihood sequence estimation demodulator 6 of this embodiment generates a branch metric for each state based on the Viterbi algorithm based on transmission line information held in advance. A generation unit 31, a transmission path information table 32 that holds transmission path information corresponding to an assumed transmission state in advance, an ACS unit 33 that selects a surviving path of the Viterbi algorithm, and a path for each state based on the Viterbi algorithm A path memory update unit 34 that updates and holds a memory (transmission sequence candidate corresponding to a path), a path metric update unit 35 that updates and holds a path metric for each state based on the Viterbi algorithm, and a path memory update unit 34 A decoded data output unit 36 that determines and outputs the decoding result based on the path memory held in It is made.

  The operation of the present embodiment will be described with reference to FIGS. Here, it is assumed that the transmitter has two transmitting antennas and the receiver has one receiving antenna 1. However, the present invention is not limited to this, and the number of transmitting antennas and the number of receiving antennas can be any number. If a corresponding algorithm is used, the operation of this embodiment can be applied.

  Here, when the transmitter transmits a signal that has been subjected to DQPSK (Differential Quadrature Phase Shift Keying) modulation from the same information bit sequence (case # 1), the transmitter has been DQPSK modulated from the same information bit sequence. Assuming a case where a signal is transmitted from one antenna and DQPSK shifted by π / 4 from the same information bit sequence is transmitted from the other antenna (case # 2), the receiver side determines case # 1 and case # 2. An example of performing a demodulation operation with automatic determination will be described.

  For case # 1, the transmission path estimation type maximum likelihood sequence estimation demodulator 5 and the transmission path information holding type maximum likelihood sequence estimation demodulator 6 can demodulate, but for case # 2, Only the transmission path information holding type maximum likelihood sequence estimation demodulator 6 can demodulate. However, if the transmission path information holding maximum likelihood sequence estimation demodulator 6 is optimized for case # 2, the reception quality for case # 1 is demodulated by the transmission path information holding maximum likelihood sequence estimation demodulator 6 Is inferior to the case of demodulating by the channel estimation type maximum likelihood sequence estimation demodulator 5.

  First, the high frequency unit 2 performs quadrature detection, downsampling, and A / D conversion on the analog signal received by the receiving antenna 1 to extract a complex baseband received signal. The reception signal memory 3 holds a signal in a range necessary for demodulation among the extracted complex baseband reception signals.

  Since the demodulator control unit 8 does not know whether the received signal is transmitted in Case # 1 or Case # 2, first, the switch 4 includes the transmission path estimation type maximum likelihood sequence estimation demodulator 5 and the received signal memory 3. Control is performed so that the transmission path estimation type maximum likelihood sequence estimation demodulator 5 performs the demodulation operation. The transmission path estimation type maximum likelihood sequence estimation demodulator 5 reads a digital complex baseband signal from the reception signal memory 3, estimates transmission path information for the read reception signal, and performs maximum likelihood sequence estimation based on the Viterbi algorithm. The reliability information obtained by the estimation process is output to the demodulation method selection unit 7. The demodulation method selection unit 7 holds reliability information.

  Next, the demodulator control unit 8 controls the switch 4 so that the transmission path information holding type maximum likelihood sequence estimation demodulator 6 and the received signal memory 3 are connected, and the transmission path information holding type maximum likelihood sequence estimation demodulation. The demodulation operation by the device 6 is executed. The transmission path information holding type maximum likelihood sequence estimation demodulator 6 reads a digital complex baseband signal from the reception signal memory 3 and stores a Viterbi algorithm sequence stored in the transmission path information table 32 for the read reception signal. Maximum likelihood sequence estimation based on the channel estimation value determined by the candidate is performed, and reliability information obtained by the estimation process is output to the demodulation scheme selection unit 7. The demodulation method selection unit 7 holds this reliability information.

  The demodulation method selection unit 7 selects the one having the higher reliability of the two reliability information held above. As the reliability information, for example, a cumulative metric value obtained by cumulatively adding updated values of the most likely path metric value among surviving paths based on the Viterbi algorithm may be used. Further, the demodulation scheme selection unit 7 may reduce selection errors by performing weighting determination on the reliability information.

  Then, the demodulator control unit 8 determines a demodulation operation parameter and a demodulation method based on the selection result of the demodulation method selection unit 7, and switches the switch 4 so that the demodulator corresponding to the determination result operates.

Next, the operation of the transmission path estimation type maximum likelihood sequence estimation demodulator 5 will be described with reference to FIG. First, the branch metric generation unit 21 obtains a branch metric value BM _k ^{P according} to the following formulas (1) to (4) based on the transmission path estimation value c _k ^S output from the transmission path estimation unit 23. Here, the step time corresponding to the symbol rate of the received signal and k, the condition number based on the Viterbi algorithm and S, the path number for each state based on the Viterbi algorithm is P, a replica of the received signal and r ^ _k ^P , the received signal and r _k, a transmission sequence candidate and J _k ^d, the transmission sequence number is d, the path metric value PM _k ^P.

In the present embodiment, the transmission path estimation value C _k ^{S is set} to 1 tap in the above calculation, but a plurality of transmission path taps may be used depending on the delay time of the delay wave existing in the transmission path. Next, the ACS unit 22 selects a surviving path for each state from the path based on the Viterbi algorithm based on the branch metric value obtained by the branch metric generating unit 21, and sets the path metric value corresponding to the selected path to the path metric. The data is output to the update unit 25, and the transmission sequence candidate corresponding to the selected path is output to the path memory update unit 24.

The transmission path estimation unit 23 performs calculation according to the following equation (5) based on the LMS (Least Mean Square) algorithm according to the surviving path selected by the ACS unit 22, and updates the transmission path estimation value. μ _k-1 ^S is a step size parameter. Note that the transmission path estimation unit 23 does not calculate the surviving path information selected by the ACS unit 22 in the initial transmission path estimation. For example, the transmission path estimation unit 23 uses the path information held as the initial value. Get an estimate.

  The path memory update unit 24 stores (holds) transmission sequence candidates corresponding to the surviving paths output from the ACS unit 22 for each state (for each state number) based on the Viterbi algorithm. The path metric update unit 25 stores the updated path metric value corresponding to the surviving path output from the ACS unit 22 for each state based on the Viterbi algorithm. Here, as the reliability information, a cumulative metric value obtained by accumulating the update value of the path metric value is used, and the path metric update unit 25 calculates the cumulative metric value and supplies it to the demodulation method selection unit 7 as the reliability information. It will output.

  The decoded data output unit 26 selects the state number with the highest reliability among the path metric values stored in the path metric update unit 25, and selects the transmission sequence candidate stored in the path memory update unit 24. A transmission sequence candidate corresponding to the state number is selected and output as decoded data to a user apparatus or the like.

Next, the operation of the transmission path information holding maximum likelihood sequence estimation demodulator 6 will be described with reference to FIG. First, the branch metric generation unit 31 obtains a branch metric value BM _k ^P according to the following equations (6) to (8) using the transmission path value A _k ^S stored in the transmission path information table 32. The transmission path estimation value A _k ^S is assumed to be held in advance as the transmission path information table 32.

In the present embodiment, the transmission path estimation value A _k ^S is 1 tap in the above calculation, but a plurality of transmission path taps may be used depending on the delay time of the delay wave existing in the transmission path. The ACS unit 33 selects a surviving path for each state from the path based on the Viterbi algorithm from the branch metric value calculated by the branch metric generating unit 31, and outputs a path metric value corresponding to the selected path to the path metric updating unit 35. In addition, a transmission sequence candidate corresponding to the selected path is output to the path memory update unit 34.

  The path memory update unit 34 stores (holds) the transmission sequence candidate corresponding to the surviving path output from the ACS unit 32 for each state (for each state number) based on the Viterbi algorithm. The path metric update unit 35 stores the updated path metric value corresponding to the surviving path output from the ACS unit 32 for each state based on the Viterbi algorithm. Here, as the reliability information, a cumulative metric value obtained by accumulating the update value of the path metric value is used, and the path metric update unit 35 calculates the cumulative metric value and supplies it to the demodulation method selection unit 7 as the reliability information. It will output.

  The decoded data output unit 36 selects the state number with the highest reliability among the path metric values stored in the path metric update unit 35, and selects the transmission sequence candidate stored in the path memory update unit 34. A transmission sequence candidate corresponding to the state number is selected and output as decoded data to a user apparatus or the like.

  In the above description, the case # 2 and case # 2 are considered. However, the present invention is not limited to this, and the number of modulation schemes and the types of schemes to be considered are arbitrary. For example, for other modulation schemes that can be demodulated by the channel estimation type maximum likelihood sequence estimation demodulator 5, the demodulator control unit 8 sets transmission parameters corresponding to the modulation scheme to the channel estimation type maximum likelihood sequence estimation demodulator 5. In addition, the transmission path information holding type maximum likelihood sequence estimation demodulator 6 can be instructed to perform the same processing as in the case # 1. For other modulation schemes that can be demodulated by the transmission path estimation type maximum likelihood sequence estimation demodulator 5, transmission path estimation values corresponding to the scheme are held in the transmission path information table 32, and the demodulator control unit 8. Can instruct the transmission parameters according to the modulation scheme to the transmission path estimation type maximum likelihood sequence estimation demodulator 5 and the transmission path information holding type maximum likelihood sequence estimation demodulator 6 and perform the same processing as in the case # 2. .

  When it is necessary to assume three or more types of cases, the demodulator control unit 8 designates a plurality of transmission parameters according to the modulation scheme, calculates reliability information corresponding to each indication, and demodulates the transmission parameters. The scheme selection unit 7 selects the transmission parameter of the modulation scheme corresponding to the reliability information having the highest reliability among the calculated reliability information. Then, the demodulator controller 8 may instruct demodulation based on the selection result.

  As described above, in this embodiment, the transmission path estimation type that extracts the reliability information that becomes the evaluation index of the reception quality by estimating the transmission path information based on the received signal and performing the maximum likelihood sequence estimation based on the Viterbi algorithm. Transmission path information for preliminarily holding transmission path information determined by a maximum likelihood sequence estimation demodulator 5 and a sequence candidate in the Viterbi algorithm, performing maximum likelihood sequence estimation based on the transmission path information, and extracting reliability information The maximum likelihood sequence estimation is performed by the two demodulators, the holding maximum likelihood sequence estimation demodulator 6 and the demodulation is performed using the demodulator from which the reliability information with high reliability is obtained. For this reason, it is possible to automatically determine and demodulate a signal transmitted by any of the modulation methods of case # 1 and case # 2. Further, even when the number of modulation schemes to be considered (which may be transmitted) increases, demodulation can be performed without increasing the circuit scale.

  For case # 1, channel estimation type maximum likelihood sequence estimation demodulator 5 is selected as a demodulation method with better reception quality, and for case # 2, channel information holding type maximum likelihood sequence estimation. Since the demodulator 6 is selected, it is possible to demodulate each modulation method without degrading the reception quality. Further, in case # 2, if the transmission signal from one transmission antenna is blocked by the blockage, the transmission quality estimation type maximum likelihood sequence estimation demodulator 5 is selected to improve the reception quality. Can do.

Embodiment 2. FIG.
FIG. 4 is a diagram illustrating a functional configuration example of the second embodiment of the receiving device according to the present invention. As shown in FIG. 4, the receiving apparatus according to the present embodiment includes transmission path estimation type maximum likelihood sequence estimation demodulator 5, transmission path information holding maximum likelihood sequence estimation demodulator 6 and switch of the receiving apparatus according to the first embodiment. 4 is deleted, a transmission line information is estimated from the received signal, a maximum likelihood sequence estimation demodulator 9 that performs maximum likelihood sequence estimation based on the Viterbi algorithm is added, and the demodulator control unit 8 is replaced with the demodulator control unit 8a. This is the same as the receiving apparatus of the first embodiment. Components having the same functions as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. Hereinafter, a different part from Embodiment 1 is demonstrated.

  In the first embodiment, the transmission path estimation type maximum likelihood sequence estimation demodulator 5 and the transmission path information holding type maximum likelihood sequence estimation demodulator 6 are provided as separate demodulators. However, in this embodiment, transmission path estimation is performed. Of the maximum likelihood sequence estimation processing based on two types of Viterbi algorithms, a type processing and a transmission path information holding type, a common part is shared.

  FIG. 5 is a diagram illustrating a configuration example of the maximum likelihood sequence estimation demodulator 9 according to the present embodiment. As shown in FIG. 5, the maximum likelihood sequence estimation demodulator 9 of this embodiment includes a transmission path estimation type branch metric generation unit 41, a transmission path information holding type branch metric generation unit 42, a selector 43, and an ACS unit. 44, a path memory update unit 45, a path metric update unit 46, and a decoded data output unit 47.

  In the first embodiment, the demodulator control unit 8 switches between the two types of processing of the transmission path estimation type and the transmission path information holding type by switching the switch 4. The controller control unit 8a switches between these two types of processing by controlling the selector 43 of the maximum likelihood sequence estimation demodulator 9.

  The transmission channel estimation type branch metric generation unit 41 performs the same processing as the branch metric generation unit 21 of the transmission channel estimation type maximum likelihood sequence estimation demodulator 5 of the first embodiment, and transmits the transmission channel information holding type branch metric generation unit 42. Performs the same processing as the branch metric generation unit 31 of the transmission path information holding maximum likelihood sequence estimation demodulator 6 of the first embodiment.

  The ACS unit 44 has the functions of the ACS unit 22 and the ACS unit 33 of the first embodiment, and the path memory update unit 45 has the functions of the path memory update unit 24 and the path memory update unit 34 of the first embodiment. The path metric updating unit 46 has the functions of the path metric updating unit 25 and the path metric updating unit 25 of the first embodiment, and the decoded data output unit 47 is the decoded data output unit 26 of the first embodiment. And the function of the decoded data output unit 36.

  The demodulation processing procedure and processing method of the present embodiment other than those described above are the same as those of the first embodiment.

  As described above, in this embodiment, the maximum likelihood sequence estimation similar to that in Embodiment 1 is performed so that the demodulator circuit is shared for two types of transmission path estimation type processing and transmission path information holding type. did. Therefore, the circuit scale can be further reduced while achieving the same effect as that of the first embodiment.

Embodiment 3 FIG.
FIG. 6 is a diagram illustrating an example of a functional configuration of the receiving apparatus according to the third embodiment of the present invention. As shown in FIG. 6, the receiving apparatus according to the present embodiment includes a demodulator control unit 8a and a maximum likelihood sequence estimation demodulator 9 of the receiving apparatus according to the second embodiment, and a demodulator control unit 8b and a maximum likelihood sequence estimation demodulation, respectively. It is the same as that of the receiving apparatus of Embodiment 2 except adding the phase rotation part 10 instead of the device 9a. Components having the same functions as those in the first embodiment or the second embodiment are denoted by the same reference numerals and description thereof is omitted. Hereinafter, a different part from Embodiment 2 is demonstrated.

  In the present embodiment, the phase rotation unit 10 is provided in the previous stage of the maximum likelihood sequence estimation demodulator 9a. The demodulator control unit 8b instructs the phase rotation unit 10 on the amount of phase rotation to be given to the digital complex baseband signal, and the phase rotation unit 10 applies phase rotation to the digital complex baseband signal based on the instruction, thereby rotating the phase. The later digital complex baseband signal is output to the maximum likelihood sequence estimation demodulator 9a. The maximum likelihood sequence estimation demodulator 9a performs the same processing as the maximum likelihood sequence estimation demodulator 9 of the second embodiment on the digital complex baseband signal after phase rotation. The demodulation processing procedure and processing method of the present embodiment other than those described above are the same as those of the second embodiment.

  Although the phase rotation unit 10 is added to the configuration of the second embodiment here, the phase rotation unit 10 may be added to the configuration of the first embodiment. In this case, if the phase rotation unit 10 is added between the reception signal memory 3 and the switch 4, the demodulator control unit 8 instructs the phase rotation unit 10 to specify the amount of phase rotation as in the present embodiment. Good.

  As described above, in the present embodiment, the phase rotation unit 10 is added to the configuration of the second embodiment, and the demodulator control unit 8b instructs the phase rotation unit 10 about the phase rotation amount. Therefore, an arbitrary phase rotation can be applied to the received signal, and the demodulator operating parameter M (π / M shift DQPSK) corresponding to the assumed transmission state can be handled. Therefore, π / M shift DQPSK modulation can be estimated, and the range in which the modulation scheme can be estimated is expanded.

  Further, by performing phase rotation, it is possible to obtain reliability information including the carrier frequency deviation while changing the frequency at a frequency interval within a demodulatable range with respect to the carrier frequency deviation. For this reason, ideal frequency deviation estimation and correction can be performed, and reception quality can be improved.

Embodiment 4 FIG.
FIG. 7 is a diagram illustrating an example of a functional configuration of the receiving apparatus according to the fourth embodiment of the present invention. As shown in FIG. 7, the receiving apparatus of this embodiment includes a demodulator control unit 8b and a maximum likelihood sequence estimation demodulator 9a of the receiving apparatus of the third embodiment, and a demodulator control unit 8c and a maximum likelihood sequence estimation demodulation, respectively. The receiver 9b is the same as the receiver of the third embodiment except that a variable delay device 11 that performs arbitrary time delay processing on the signal read from the received signal memory 3 is added instead of the device 9b. Components having the same functions as those of the first embodiment, the second embodiment, or the third embodiment are denoted by the same reference numerals, and description thereof is omitted. Hereinafter, a different part from Embodiment 3 is demonstrated.

  In the present embodiment, the demodulator control unit 8 c instructs the variable delay unit 11 on the delay time amount, and the variable delay unit 11 instructs the digital complex baseband signal stored in the reception signal memory 3. Give a time delay based on. Then, the moving rotation unit 10 performs phase rotation on the digital complex baseband signal after the time delay in the same manner as in the third embodiment, and the maximum likelihood sequence estimation demodulator 9b performs phase rotation in the same manner as in the third embodiment. The subsequent digital complex baseband signal is processed in the same manner as the maximum likelihood sequence estimation demodulator 9 of the second embodiment. The demodulation processing procedure and processing method of the present embodiment other than those described above are the same as those of the third embodiment.

  Although the variable delay device 11 is added to the configuration of the third embodiment here, the phase rotation unit 10 and the variable delay device 11 may be added to the configuration of the first embodiment. In this case, the phase rotation unit 10 and the variable delay unit 11 are added between the reception signal memory 3 and the switch 4, and the demodulator control unit 8 instructs the phase rotation unit 10 on the amount of phase rotation, and the variable delay unit 11 is instructed. The time delay amount may be indicated.

  Here, the variable delay device 11 is added to the configuration of the third embodiment, and both the time delay and the phase rotation processing are performed. However, the receiving apparatus according to the first or second embodiment is used. A variable delay device 11 may be added to perform time delay processing. When adding the variable delay device 11 to the receiving apparatus of the second embodiment, the variable delay device 11 is arranged before the maximum likelihood sequence estimation demodulator 9a, and the demodulator control unit 8b is similar to the present embodiment. The delay time amount may be instructed to the variable delay device. When the variable delay device 11 is added to the receiving apparatus of the first embodiment, the variable delay device 11 is arranged between the received signal memory 3 and the switch 4, and the demodulator control unit 8 is the same as the present embodiment. The delay time amount may be instructed to the variable delay device.

  As described above, in this embodiment, a function of adding an arbitrary delay adjustment to the digital complex baseband signal read from the reception signal memory 3 is added. For this reason, since the symbol timing sampling position can be arbitrarily changed, the ideal symbol timing is selected based on the reliability information including the symbol timing position by obtaining the reliability information with the symbol timing changed. And the reception quality can be improved.

  As described above, the receiving apparatus and the demodulation method according to the present invention are useful for a receiving apparatus that receives a digital radio modulated signal, and are particularly suitable for a receiving apparatus that performs demodulation processing by estimating a modulation scheme. .

It is a figure which shows the function structural example of Embodiment 1 of the receiver concerning this invention. 3 is a diagram illustrating a configuration example of a transmission path estimation type maximum likelihood sequence estimation demodulator according to Embodiment 1. FIG. 3 is a diagram illustrating a configuration example of a transmission path information holding maximum likelihood sequence estimation demodulator according to Embodiment 1. FIG. It is a figure which shows the function structural example of Embodiment 2 of the receiver concerning this invention. FIG. 11 is a diagram illustrating a configuration example of a maximum likelihood sequence estimation demodulator according to the second embodiment. It is a figure which shows the function structural example of Embodiment 3 of the receiver concerning this invention. It is a figure which shows the function structural example of Embodiment 4 of the receiver concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reception antenna 2 High frequency part 3 Received signal memory 4 Switch 5 Transmission path estimation type maximum likelihood sequence estimation demodulator 6 Transmission path information retention type maximum likelihood sequence estimation demodulator 7 Demodulation system selection part 8, 8a, 8b, 8c Demodulator control Unit 9, 9a, 9b maximum likelihood sequence estimation demodulator 10 phase rotation unit 11 variable delay unit 21, 31 branch metric generation unit 22, 33, 44 ACS unit 23 transmission path estimation unit 24, 34, 45 path memory update unit 25, 35, 46 Path metric update unit 26, 36, 47 Decoded data output unit 32 Transmission path information table 41 Transmission path estimation type branch metric generation section 42 Transmission path information holding type branch metric generation section 43 selector

Claims (7)

First transmission path information is estimated based on the received signal, maximum likelihood sequence estimation is performed using a Viterbi algorithm based on the transmission parameter including modulation scheme information, the received signal, and the first transmission path information. A channel estimation type maximum likelihood sequence estimation demodulating means for calculating first reliability information serving as an evaluation index of reception quality based on a likelihood sequence estimation result;
Second transmission path information determined based on a sequence candidate in the Viterbi algorithm is stored in advance, and maximum likelihood sequence estimation is performed based on the transmission parameter, the received signal, and the second transmission path information. A channel information holding type maximum likelihood sequence estimation demodulating means for calculating the second reliability information based on the sequence estimation result;
For each demodulating means, a control means for controlling the operation and non-operation of the instruction of the transmission parameter,
And demodulation scheme selection means for selecting the first reliability information and the highest reliability before Symbol demodulator hand stage that corresponds to the information of the reliability of the second reliability information,
With
Said control means, said transmission parameter is determined based on the demodulation means the demodulation scheme selection means has selected, determined the transmission parameters to the demodulation scheme demodulating means selection means selects Instructs its demodulator A receiving apparatus characterized by operating. The transmission channel estimation type maximum likelihood sequence estimation demodulating means includes:
Transmission path estimation means for estimating the first transmission path information;
First branch metric generation means for obtaining a branch metric value for each state based on the Viterbi algorithm using the first transmission path information;
A first ACS means for selecting a surviving path of the Viterbi algorithm based on the branch metric value and obtaining a path metric value and a transmission sequence candidate corresponding to the selected path;
First path metric update means for calculating the first reliability information based on the path metric value;
With
The transmission path information holding type maximum likelihood sequence estimation demodulating means,
Second branch metric generation means for obtaining a branch metric value for each state based on the Viterbi algorithm using the second transmission path information;
Second ACS means for selecting a surviving path of the Viterbi algorithm based on the branch metric value obtained by the second branch metric generating means, and obtaining a path metric value and a transmission sequence candidate corresponding to the selected path;
Second path metric update means for calculating the second reliability information based on the path metric value obtained by the second ACS means;
The receiving apparatus according to claim 1, further comprising: 3. The receiving apparatus according to claim 1, wherein the transmission path estimation type maximum likelihood sequence estimation demodulating means and the transmission path information holding type maximum likelihood sequence estimation demodulating means are implemented as the same circuit. Phase rotation means for performing phase rotation for a predetermined phase with respect to the received signal;
Further comprising
The transmission path estimation type maximum likelihood sequence estimation / demodulation means and the transmission path information hold type maximum likelihood sequence estimation / demodulation means use the received signal after phase rotation as a received signal to be processed. Or the receiving apparatus of 3. A delay processing means for performing a time delay process for a predetermined delay time on the received signal;
Further comprising
The transmission path estimation type maximum likelihood sequence estimation demodulating means and the transmission path information holding type maximum likelihood sequence estimation demodulating means use the received signal after time delay processing as a received signal to be processed. 4. The receiving device according to 2 or 3. A delay processing means for performing a time delay process for a predetermined delay time on the received signal;
Further comprising
5. The receiving apparatus according to claim 4, wherein the phase rotation means uses the reception signal after the time delay processing as a reception signal to be phase rotated. First transmission path information is estimated based on the received signal, maximum likelihood sequence estimation is performed using a Viterbi algorithm based on the transmission parameter including modulation scheme information, the received signal, and the first transmission path information. A channel estimation type maximum likelihood sequence estimation demodulation step for calculating first reliability information that is an evaluation index of reception quality based on the likelihood sequence estimation result;
Second transmission path information determined based on a sequence candidate in the Viterbi algorithm is stored in advance, and maximum likelihood sequence estimation is performed based on the transmission parameter, the received signal, and the second transmission path information. A channel information holding maximum likelihood sequence estimation demodulation step for calculating second reliability information based on the sequence estimation result;
A parameter indicating step for indicating the transmission parameter;
And demodulation scheme selection step of selecting the first reliability information as the most reliable previous Symbol demodulation steps that correspond to the information of the reliability of the second reliability information,
Including
In the parameter instruction step, the transmission parameter is determined based on the demodulation step selected in the demodulation method selection step,
The demodulation method selected in the demodulation method selection step performs demodulation based on the transmission parameter determined in the parameter instruction step.

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