JP2002111754A - Reception demapping device that can support multiple modulation schemes - Google Patents

Abstract

(57) [Summary] [Problem] Switching of demapping processing is easy,
Provided is a reception demapping device that can support a plurality of modulation methods without reloading new demapping software corresponding to the modulation method. A reception demapping device for performing a demapping process of reproducing a symbol value of an original data sequence from a digital modulation signal modulated based on an arbitrary one of a plurality of predetermined modulation methods. , A digital signal processing unit 2 for generating a symbol value from a received digital modulation signal in accordance with demapping software loaded in advance in a program memory 3, and a parameter 5 corresponding to a modulation scheme of the received digital modulation signal is input from a parameter input unit 4. It is input to the digital signal processor 2 as an argument to the demapping software.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reception demapping device provided in a reception unit of a radio, and more particularly to a reception digital modulation signal modulated by a plurality of modulation schemes in a so-called software radio which realizes a radio function by software. The present invention relates to a receiving demapping device capable of generating a symbol value of an original data sequence from a received data.

[0002]

2. Description of the Related Art With the rapid development of mobile communication systems in recent years, users can use various types of services, such as voice communication, data communication such as mail and the Internet, and moving image communication.
It is becoming more diverse. With the diversification of such usage forms, there is an increasing demand for what is called a multi-mode terminal, in which a single terminal can use a plurality of systems. In response to this trend, PHS (Personal Handy-phone Sy
A dual mode terminal that can use a single terminal with a PDC (Personal Digital Cellular) and a PDC (Personal Digital Cellular) has been developed and put on the market.

[0003] This dual mode terminal has two pieces of hardware, one realizing a function corresponding to the PHS and the other realizing a function corresponding to the PDC, housed in one housing. Therefore, this dual mode terminal is compatible with PHS and PDC, but it has not been possible to realize a function corresponding to another wireless communication system or to upgrade an already built-in function. .

As one means for solving this problem, a wireless communication function or a part of the wireless communication function is realized by software processing using one piece of hardware such as a digital signal processor, and only software is replaced. A so-called software defined radio, which is compatible with a plurality of wireless communication systems and can upgrade a built-in function, has been proposed and studied for its practical use.

The receiving demapping device built in the software defined radio has a function of demapping a signal modulated by a plurality of modulation schemes, which differs depending on each radio communication system. Demapping is a process of generating a symbol value of an original data sequence from a received digital modulation signal. However, the conventional reception demapping device built in the software defined radio can only support a modulation method prepared in advance. In addition, in order to switch the modulation method, it was necessary to take steps to suspend the demapping process once, load the desired demapping software from the memory into the processor, and then start the demapping process again. . Furthermore, in order to perform a demapping process on a signal modulated by another modulation method that is not prepared,
It was necessary to newly download demapping software for realizing a function of demapping a signal modulated by the modulation method.

A conventional reception demapping device in such a software defined radio includes a processor and a memory connected to the processor.
SK demapping software, π / 4-QPSK demapping software, GMSK demapping software, and ASK demapping software are stored. With such a configuration, the demapping software in the memory is loaded into the processor in accordance with a desired modulation scheme, and the processor performs demapping processing on the input modulated signal to obtain a desired demapping processing output.

When switching the modulation method, the processing is temporarily stopped, another demapping software in the memory is reloaded into the processor, and the processor performs the demapping processing again. For example, when the BPSK modulation method is selected, BPSK demapping software is loaded into the processor, the input BPSK modulation signal is subjected to demapping processing, and a demodulated signal is output. When the modulation scheme is changed to π / 4-QPSK, the BPSK demapping process is temporarily stopped, and by selecting π / 4-QPSK, the π / 4-QPSK demapping software is reloaded from the memory into the processor. Π / 4-QPSK demapping processing is performed on the input π / 4-QPSK modulated signal.

In order to perform a demapping process on a signal modulated by the QPSK modulation method using the conventional receiving demapping device, a new QPSK demapping software is downloaded to a memory, and then the same as above. Must be performed. Therefore, switching to a demapping process corresponding to a desired modulation method requires a great deal of time and procedures, and a system in which the modulation method is switched for each time slot in accordance with the stability of the wireless transmission path is required. There was a drawback that it could not be substantially handled.

Further, in the conventional receiving demapping device,
In order to perform demapping processing corresponding to many modulation schemes, it is necessary to store demapping software for the number of expected modulation schemes in a memory, which requires a very large capacity memory. Had disadvantages.
If the demapping software of the new modulation method is added to the memory twice or three times by downloading, the capacity of the built-in memory becomes insufficient and the memory itself becomes larger. It also had the serious disadvantage that it had to be replaced with memory.

Further, in the conventional receiving demapping device, downloading the demapping software corresponding to the new modulation scheme leads to an increase in the total amount of software downloaded to the radio, and takes a very long time to download. Has the disadvantage of requiring

[0011]

As described above, in the conventional receiving demapping device, not only many procedures and a long time are required to switch to demapping processing corresponding to a desired modulation method, but also a new receiving demapping device is required. When the demapping software corresponding to the modulation method is downloaded, there is a possibility that the memory capacity is insufficient, and there is a problem that the total amount of software to be downloaded increases.

The present invention solves such a problem,
It is an object of the present invention to provide a receiving demapping device that can easily switch the demapping process and can handle a plurality of modulation schemes without reloading new demapping software corresponding to the modulation scheme.

[0013]

In order to solve the above-mentioned problems, the present invention provides a method of converting an original data sequence from a received digital modulation signal modulated by an arbitrary one of a plurality of predetermined modulation systems. In a reception demapping device that performs a demapping process of generating a symbol value, a parameter input unit that inputs a parameter for a demapping process corresponding to a modulation scheme of a received digital modulation signal,
A demodulation unit configured to be compatible with a plurality of modulation schemes, demodulating a received digital modulation signal in accordance with the parameter according to the demodulation scheme corresponding to the modulation scheme of the digital modulation signal, and decoding an output signal from the demodulation unit in accordance with the parameter And at least one decoding unit.

The demodulation unit and the decoding unit can be specifically realized by a digital signal processing unit. The digital signal processing unit demodulates and decodes the data according to the pre-loaded software for the demapping process. Is performed by digital signal processing, and a symbol value is generated from the received digital modulation signal. In this case, parameters for the demapping process corresponding to the modulation method of the digital modulation signal are input to the digital signal processing unit as arguments to software loaded in the digital signal processing unit.

Specifically, the parameter input unit includes a modulation type, a modulation multi-level number, a modulation index when the modulation type is frequency modulation, a phase offset when the modulation type is phase modulation, Information specifying ON / OFF of decoding and ON / OFF of differential decoding is input as a parameter.

As described above, according to the present invention, parameters such as the type of modulation scheme, the number of modulation levels, the phase offset (in the case of PSK), and the modulation index (in the case of FSK) are de-mapped to, for example, a digital signal processing unit. By providing as an argument to, a demapping device capable of demapping a signal modulated by a plurality of modulation schemes and outputting a symbol value of an original data sequence as a demodulated signal can be provided. .

Therefore, since it is not necessary to load the demapping software from the memory to the processor for each modulation scheme, the demapping process is instantaneously switched, and various demapping software can be used without downloading new demapping software again. It is possible to perform a demapping process corresponding to the modulation method of (1).

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a reception demapping device according to an embodiment of the present invention. Input terminal 1
Is input with a received digital modulation signal to be subjected to demapping processing, and is subjected to demapping processing by the digital signal processing unit 2. The digital signal processing unit 2 is a device that realizes a desired function by digital signal processing, and is, for example, a DSP (Digital Signal Processor) or an FPGA (Field Programmable Processor).
Gate array) is used. The digital signal processing unit 2 performs a demapping process on the received digital modulation signal in accordance with demapping software (hereinafter, referred to as demapping software) loaded in a built-in program memory 3.

Here, the demapping software loaded into the program memory 3 is common to a plurality of modulation methods, and the demapping software includes, for example, a CP.
The parameter 5 for the demapping process corresponding to the modulation method of the received digital modulation signal, which is input from the parameter input unit 4 made of U, is given as an argument. Therefore, by changing the parameter 5 in accordance with the modulation method of the received digital modulation signal, the digital signal processing unit 2 can use a common type of demapping software to support a plurality of modulation methods. It becomes possible. The demapping process is performed in the digital signal processing unit 2 in this manner, and a symbol value sequence is generated and output from the output terminal 6.

In FIG. 1, a digital signal processing unit 2
2 is a block diagram showing functions realized by the demapping software loaded in the program memory 3. The digital signal processing unit 2 basically has the functions of a demodulation unit 10, a Gray decoding unit 14, and a differential decoding unit 15. The demodulation unit 10 includes a PSK demodulation unit 11, an FSK
It has a function of a demodulation unit 12 and a QAM demodulation unit 13 and switches SW1 and SW2 for switching between them. On the other hand, the gray decoding unit 14 and the differential decoding unit 15 have a structure that can be individually bypassed by the switches SW3 to SW6 and the bypass paths L1 and L2, thereby enabling the differential decoding ON / OFF and the gray decoding. ON / OFF can be selected.

On the other hand, as the parameter 5 for the demapping process, the type of the modulation method (PSK / FSK / Q
AM), modulation level (power of 2; power of 4 in QAM), phase offset (in the case of PSK), modulation index (F
SK) can be appropriately set according to the modulation method of the received digital modulation signal. By giving the parameter 5 as an argument to the demapping software loaded in the program memory 3, the demapping process corresponding to the received digital modulation signal is executed in the digital signal processing unit 2.

As an example, first, the parameter 5 is initially set to “modulation type = PSK”, “modulation multi-level number = 4”, “phase offset = 0”, “gray decoding ON”, “differential decoding OFF”. Next, a case where the demodulation parameter 5 is changed to “modulation scheme type = QAM”, “modulation multi-level number = 16”, “gray decoding OFF”, and “differential decoding ON” will be described. .

First, the PSK demapping process is selected, and the PSK signal of “modulation multi-level number = 4” and “phase offset = 0” is applied to the PSK signal input to the PSK demodulation unit 11.
(QPSK) demodulation is performed. Next, the PSK demodulation unit 11
Are input to the Gray decoding unit 14, where gray decoding processing is performed. The output from the gray decoding unit 14 bypasses the differential decoding unit 15 and is output from the output terminal 6.

Next, the parameter 5 is set to "modulation type = QAM", "modulation multi-level number = 16", "Gray decoding O"
FF ”and“ differential decoding ON ”, the QAM demapping process is selected, and the QAM signal input to the QAM demodulation unit 12 has a QAM signal of“ modulation multi-level number = 16 ”.
(16QAM) demapping processing is performed. Next, Q
The output from the AM demodulation unit 12 bypasses the Gray decoding unit 14 and is input to the differential decoding unit 15 to be subjected to differential decoding processing and output from the output terminal 6.

As described above, in the receiving demapping apparatus according to the present embodiment, it is possible to instantaneously switch to a desired demapping process by setting the parameter 5 without loading demapping software from the memory. Therefore, even in a communication system in which the modulation scheme is switched for each time slot, a demapping process adapted to the modulation scheme for each time slot is performed by adding a parameter for determining the modulation scheme to the beginning of each time slot as a pilot signal. It is possible to do.

Further, as another example, "modulation type = FSK"
A case in which the demapping process (8FSK) of “modulation multi-level number = 8”, “modulation index = 0.5”, “Gray decoding ON”, and “differential decoding ON” will be described.

In the receiving demapping device according to the present embodiment, it is not necessary to download new 8FSK demapping software in order to realize the 8FSK demapping processing function, and “modulation type = FSK” and “modulation type” as parameters. Modulation multi-level number = 8 "," modulation index =
0.5 "," Gray decoding ON "," Differential decoding ON "
, It is possible to realize a desired 8FSK demapping processing function. Therefore, it is effective in that it does not require downloading new software and does not increase the total amount of software downloaded to the wireless device.

In this embodiment, the demodulation unit 10 outputs the PS
K demodulator 11, FSK demodulator 12, and QAM demodulator 13
Has been shown, but even if a demodulation unit corresponding to another modulation method such as an ASK demodulation unit is further added, the effect of the present invention is not impaired, and it can be used more effectively. is there.

(Regarding PSK demodulation unit 11) Next, FIG.
The configuration of the PSK demodulation unit 11 will be described with reference to FIG. The in-phase component and quadrature component data of the PSK signal input from the input terminal 21 are input to the signal point determination unit 22. The signal point determination unit 22 determines a signal point on the phase plane of the input PSK signal. The method of determining a signal point on this phase plane is as follows.

In PSK, information of a certain symbol is modulated and transmitted as phase information of a baseband signal. However, the modulated signal input to the receiving demapping device via the radio propagation path deviates from the original signal point set at the time of modulation due to noise, interference, fading, and the like. Even if the signal point of the received signal deviates from the original signal point, the original phase information can be obtained by determining the area where the signal point exists on the phase plane.

In the case of n-valued PSK, signal points are placed on n points at which the phase difference between adjacent signal points (this is called a unit phase difference) is constant on a unit circle centered on the origin on the phase plane. A point is placed. Here, it is assumed that n is a power of 2. The unit phase difference θ is expressed as θ = 2π / n, and the phase φ of the n signal points is expressed as φ = θ · k + α (k = 0, 1,..., N−1). Where α
Is the phase offset. This is shown in FIG. 3 by taking the case of 8-level PSK as an example.

The phase plane can be divided into n regions corresponding to the phase information by a straight line that bisects the angle between each signal point and an adjacent signal point (this is called a determination boundary straight line). it can. This situation is shown in FIG. 4 taking the case of 8-level PSK as an example.

Therefore, the signal point of the received PSK signal is n
If it is possible to determine which of the three regions exists, the original phase information can be determined. Hereinafter, one example of a specific method for realizing this will be described.
First, according to the given phase offset, the input PSK
The in-phase component data and the quadrature component data of the signal are rotated in the negative direction about the origin on the phase plane by the magnitude of the phase offset. The amplitude values of the in-phase component data and the quadrature component data are V (I) and V (Q), the amplitude values of the rotated in-phase component data and the quadrature component data are U (I) and U (Q), and the phase offset is α. Then, the amplitude values of the in-phase component data and the quadrature component data after rotation are: U (I) = cos (−α) · V (I) −sin (−α) · V (Q) U (Q) = sin (−α) · V (I) + cos (−α) · V (Q) Then, the values of U (I) and U (Q) are stored in the memory.

Next, the existence area on the phase plane is determined for the signal points of U (I) and U (Q). A determination boundary straight line for determining an area where a signal point exists can be expressed as a (k) · Q = b (k) · I, where I is the in-phase component and Q is the quadrature component. Here, a (k) and b (k) are coefficients of the determination boundary straight line, and are represented by the following equations.

[0035]

(Equation 1)

Here, when a (k) is negative, a (k) and b (k)
Multiply each by -1. The reason for this is that when judging a signal point, the magnitude of the Q value of the judgment boundary line is compared and judged, and the coefficient a (k) of the Q of the judgment boundary line must always be positive. is there. Then, these coefficients are stored in the memory.

The number p is determined as shown in FIG. 5 for n areas divided by n / 2 decision boundary straight lines. That is, the number p represents the phase information.
k is changed from 0 to (n / 2) -1 in increments of +1. When U (I) and U (Q) satisfy the following determination conditions, the determination for that signal point ends, and the next signal point is determined. The process of starting the determination for the signal point is repeated.

[When k = (n / 4) -1 (Case 1)] a (k)
When U (Q)> b (k) · U (I) is satisfied, a (k + 1) · U (Q)> b
If (k + 1) · U (I) is satisfied, then p = n / 4 is obtained. If a (k) · U (Q)> b (k) · U (I) is not satisfied, a ( If k + 1) ・ U (Q) <b (k + 1) ・ U (I), then p = 3n / 4.

[When k is other than that (Case 2)] a
When (k) · V (Q)> b (k) · V (I), a (k + 1) · V (Q)
<B (k + 1) · V (I)

(Equation 2)

When a (k) · V (Q)> b (k) · V (I) is not satisfied, a (k + 1) · U (Q)> b (k + 1) · U (I) If

(Equation 3)

Is obtained.

However, the case of k = (n / 4) -1 (case 1) is a case where the k-th and k + 1-th two determination boundary straight lines sandwich the Q axis. This state is 8-value PSK
6 is shown in FIG. In FIG. 6, since 8-valued PSK is used, when k = (8/4) -1 = 2-1 = 1, k
The determination boundary straight line of = 1 and k = 2 sandwiches the Q axis. In this case, p = 2 or p = 6 is determined according to the determination condition of Case 1. FIG. 7 shows the case 2 using an 8-level PSK as an example. In this case, the two determination boundary straight lines do not sandwich the Q axis.
= 1 or p = 5.

The result determined by the signal point determination unit 22 is input to the table reference unit 23. The table reference unit 23 obtains a symbol value from the input number p representing the phase information with reference to a table 24 storing the correspondence between the phase information and the symbol value. The obtained symbol value is
Output from the output terminal 25.

The table 24 describes a number p representing phase information and a symbol value corresponding to the number p. The configuration of this table 24 is shown in FIG. 8, taking an 8-level PSK as an example. Considering FIG. 8 as an example, the table reference unit 23
When the number p = 2 representing the phase information is input to
Referring to table 24, when symbol value “101” corresponding to p = 2 is output and p = 6 is input,
Referring to table 24, a symbol value “001” corresponding to p = 6 is output.

By configuring the PSK demodulation unit 11 as described above, the PSK demapping process of any modulation multi-level number can be performed by changing the modulation multi-level number n and the phase offset α.

(Example of QPSK) A specific example will be described below. It is assumed that the amplitudes of the in-phase component data and the quadrature component data input to the signal point determination unit 22 are V (I) = − A V (Q) = 0 and the phase offset α = 0. However,
Let A> 0. It is assumed that the table 24 storing the correspondence between the phase information and the symbol values is configured as shown in FIG.

The coefficient of the determination boundary straight line is calculated as in the following equation and stored in the memory.

(Equation 4)

When k is changed from 0 to (n / 2) -1, that is, 1 in increments of +1, the following equation is satisfied when k = 1.

(Equation 5)

That is, α (k) · U (Q)> b (k) · U (I) is not satisfied. At this time,

(Equation 6)

That is, a (1 + 1) · V (I)> b (1 + 1) · V (Q)
And k = 1 = (n / 2) −1, the number p representing the phase information can be obtained as follows: p = n−1−k = 4-1-1 = 2.

P = 2 is input to the table reference unit 23,
The symbol value can be obtained as “00” by referring to the table 24 in FIG. Therefore, the symbol value “00” in this case is output from the output terminal 25.

(Regarding FSK demodulation unit 12) Next, FIG.
The configuration of the FSK demodulation unit 12 will be described using 0. The in-phase component data and the quadrature component data of the FSK signal input from the input terminal 31 are first input to the input buffer 32. The input buffer 32 stores in-phase component data and quadrature component data one symbol before and current in-phase component data and quadrature component data.

The in-phase component data and the quadrature component data are input to the angular velocity determining unit 33, and the angular velocity of the signal point is determined. The method for determining the angular velocity is as follows.
In FSK, information of a certain symbol is modulated and transmitted as angular velocity information of a baseband signal. The modulated signal input to the reception demapping device via the radio propagation path deviates from the original angular velocity set at the time of modulation due to noise, interference, fading, and the like. However, even if the angular velocity of the received signal deviates from the original angular velocity, the original angular velocity information can be obtained by determining the angular velocity.

In the case of n-valued FSK, given a multi-valued number n and a modulation index h, the angular velocities are different from each other such that the magnitude of adjacent angular velocities (this is called a unit angular velocity difference) ω is constant.
Value. When this is plotted on a number line, FIG.
It looks like 1. Here, it is assumed that n is a power of 2. The unit angular velocity difference ω is expressed as ω = (πh / T) / (n−1), and the n angular velocities Ω are expressed as follows: Ω = ω {− (n−1) + 2k} (k = 0, 1, .., N-1). Here, h is the modulation index, and T is the reciprocal of the symbol rate.

When the midpoint between the angular velocities adjacent to the respective angular velocities is called a judgment boundary value, the number line is divided into n regions by (n-1) judgment boundary values. This is shown in FIG.

Therefore, if it is possible to determine in which of the n regions the angular velocity of the received signal exists, the original angular velocity information can be determined. Hereinafter, one example of a specific method for realizing this will be described. In this example, the angular velocity is determined based on the values of the inner product and the outer product of the current in-phase component data and quadrature component data and the immediately preceding in-phase component data and quadrature component data. First, the reason will be described.

The signal point P (r-1) of the in-phase component and the quadrature component data of the r-1st symbol and the signal point P (r) of the in-phase component and the quadrature component data of the r-th symbol are P (r- 1) = (Acos (φ (r-1) T)), Asin (φ (r-1) T)) P (r) = (Acosφ (rT)), Asinφ (rT)). Here, φ (rT) is the phase of the r-th symbol.

If the inner product (P (r) · P (r−1)) of these two points is L and the outer product (P (r) · P (r−1)) is M, then L = A ² cos { φ (rT) −φ (r−1) T)} M = A ² sin {φ (rT) −φ (r−1) T)}, the relationship between phase and angular velocity, φ (rT) = Ω Using T + φ ((r-1) T), L = A ² cos (Ω · T) M = A ² sin (Ω · T) The inner product and outer product calculated in this way are
These are the values of the cosine function and the sine function of (angular velocity) × (reciprocal of the symbol rate), and are determined to be determined in accordance with the angular velocity.

Next, a method of determining the angular velocity will be described. Since the values of the (n-1) angular velocity determination boundary values are given by G = ω (−n + 2 + 2k) (k = 0, 1,..., N−1), the sine function and cosine of the determination boundary values The value of the function is compared with the value of the inner product and the outer product of the input in-phase component data and the input quadrature component data and determined.

Further, as shown in FIG. 13, a number s is determined for n areas divided by (n-1) judgment boundary values. That is, this number s represents angular velocity information. Signal point P (r−
1) The inner product L and the outer product M are calculated from the signal point P (r) of the r-th symbol.

<< If M> 0 >> When k is changed from (n / 2) −1 by +1 and L> cos {ω (−n + 2 + 2k)} is satisfied for the first time, s = k + 1 is obtained.

<< In the case of M <0 >> k is changed from (n / 2) -1 by −1, and when L <cos {ω (−n + 2 + 2k)} is satisfied for the first time, s = k is obtained.

The result determined by the angular velocity determining unit 33 is input to the table reference unit 34. The table reference unit 34 stores a table 35 storing the correspondence between the angular velocity information and the symbol value from the number s representing the input angular velocity information.
To find a symbol value. The obtained symbol value is output from the output terminal 36. The table 35 is provided in advance. In this table 35, a number s representing angular velocity information and a symbol value corresponding to the number s are described. This table is shown in FIG.
It is shown in FIG.

When taking FIG. 14 as an example, the table reference unit 3
4, when the number s = 7 representing the phase information is input, a symbol value “010” corresponding to s = 7 is output with reference to the table 35, and when p = 3 is input, Referring to table 35, a symbol value “011” corresponding to s = 3 is output.

By configuring the FSK demodulation unit 12 as described above, by changing the modulation multi-level number n and the modulation index h, the FSK of any modulation multi-level number and modulation index can be changed.
Demapping processing becomes possible.

(Example of 4-level FSK) A specific example will be described below.
It is assumed that the table 35 storing the correspondence between the quaternary FSK, the modulation index of 0.75, and the angular velocity information and the symbol value is configured as shown in FIG. Let the signal point of the (r-1) th symbol be P (r-1) and the signal point P (r) of the rth symbol be:

(Equation 7)

The inner product L and the outer product M are calculated by the following equations.

(Equation 8)

Since M> 0, k is (n / 2) −1,
That is, when changing from 1 to +1 at a time, when k = 2

(Equation 9)

That is, since L> cos {ω (−n + 2 + 2k)} is satisfied for the first time, the number s representing the angular velocity can be obtained as s = k + 1 = 3.

S = 3 is input to the table reference section 34,
The symbol value can be obtained as "01" by referring to the table 35 of FIG. Therefore, the symbol value “01” in this case is output from the output terminal 36.

(Regarding the QAM demodulation unit 13) Next, FIG.
6, the configuration of the QAM demodulation section 13 will be described. The in-phase component data and quadrature component data of the QAM signal input from the input terminal 41 are first input to the signal point determination unit 42. The signal point determination unit 42 determines a signal point on the phase plane of the input QAM signal. The method of determining a signal point on this phase plane is as follows.

In QAM, information of a certain symbol is modulated as both amplitude and phase information of a baseband signal.
Sent. The modulated signal input to the reception demapping device via the radio propagation path is shifted from the original signal point set at the time of modulation due to noise, interference, fading, and the like. However, even if the signal point of the received signal deviates from the original signal point, the original amplitude / phase information can be obtained by determining the area where the signal point exists on the phase plane.

The n-value QAM signal points are arranged on lattice points on the phase plane at n points where the distance between adjacent signal points is constant. Here, it is assumed that n is a power of 4.
This situation is shown in FIG. 17 taking 16-QAM as an example. When focusing only on the in-phase component, each signal point is one of n ^1/2 regions divided by n ^1/2 -1 straight lines (in-phase component determination boundary straight lines) passing through the midpoint of the signal point. Exists. This situation is shown in FIG. 18 using 16-level QAM as an example. Similarly, when attention is paid only to the quadrature component, n ^1/2 -1 pieces of areas divided by each signal point of n ^1/2 -1 present through the middle point of the signal point line (quadrature component determination boundary line) Exists in any of the This situation is shown in FIG. 19 using 16-value QAM as an example. Therefore, if it is possible to determine in which region the signal point of the received signal exists for each of the in-phase component and the quadrature component, the original amplitude / phase information can be restored.

Hereinafter, an example of a specific method for realizing this will be described. First, on the phase plane,
The number x is determined as shown in FIG. 20 for c regions divided by n ^1/2 −1 straight lines for the in-phase component. Similarly, the number y is determined as shown in FIG. 21 for n ^1/2 regions divided by n ^1/2 -1 straight lines for the orthogonal component. The combination of the numbers x and y represents the amplitude / phase information of the input signal.

Next, for the amplitude value V (I) of the input in-phase component data, k is changed from 0 to n ^1/2 -2 in increments of +1.

(Equation 10)

When the condition is satisfied, x = k + 1 is obtained. However, a> 0. k is n ^1/2 -2
If the above condition is not satisfied even when the condition is satisfied, x = n ^1/2 is obtained.

Similarly, with respect to the amplitude value V (Q) of the input orthogonal component data, k is changed from 0 to n ^1/2 -2 by +1 at a time, and

[Equation 11]

When y is satisfied, y = k + 1 is obtained. However, a> 0. k is n ^1/2 -2
If the above condition is not satisfied even when the condition is satisfied, y = n1 ^{/ 2} is obtained.

The result determined by the signal point determination unit 42 is input to the table reference unit 43. The table reference unit 43 obtains a symbol value from the input numbers x and y representing the amplitude / phase information with reference to a table 44 storing the correspondence between the amplitude / phase information and the symbol value. The obtained symbol value is output from the output terminal 45.

A table 44 storing the correspondence between the amplitude / phase information and the symbol value is given in advance. In this table 44, numbers x and y representing amplitude / phase information are stored.
And a symbol value corresponding to it. The configuration of this table 44 is shown in FIG. 22 taking 16QAM as an example.

Considering FIG. 22 as an example, the table reference unit 4
In the case where numbers x = 1 and y = 3 representing amplitude / phase information are input to No.3, x = 1 and y = 3 with reference to the table 44.
Is output to the output terminal 45.

By configuring the QAM demodulation unit 13 as described above, the QAM demapping process of any modulation multi-level number can be performed by changing the modulation multi-level number n.

(Example of 16QAM) A specific example will be described below.
It is assumed that the amplitudes of the in-phase component data and the quadrature component data input to the signal point determination unit 42 are V (I) = a V (Q) = − a. However, it is assumed that a> 0. Further, a table 4 storing the correspondence between the amplitude / phase information and the symbol value.
4 is configured as shown in FIG.

First, the in-phase component V (I) = a is first obtained when k = 2.

(Equation 12)

That is, since a <− (4-2) a + 2a · 2 = 2a is satisfied, x = 3 is obtained.

Next, the quadrature component V (Q) = − a is first obtained when k = 1.

(Equation 13)

That is, since −a <− (4-2) a + 2a · 1 = 0 is satisfied, y = 2 is obtained.

X = 3 and y = 2 are input to the table reference section 43, and by referring to the table 43 in FIG.
The symbol value can be obtained as "1111". Therefore, in this case, the symbol value “1111” is output from the output terminal 45.

(Regarding Gray Decoding Unit 14) Next, the gray decoding unit 14 will be described. Gray decoding unit 1
4, gray-coded data is input. First,
According to the given multi-valued number n, the value c before Gray encoding
And a table of gray-encoded values g (c) is created.

Next, the input data, that is, the gray-encoded value g (c) is referred to the created table, and c corresponding to g (c) is output as gray-decoded data. . Gray decoding can be performed by repeating such an operation.

(Example of Four-Level Gray Decoding) First, a table of a value c before Gray coding and a gray-coded value g (c) is created from a given multi-valued number n = 4. This table is obtained as follows. g (00) = 00 g (01) = 01 g (10) = 11 g (11) = 10 Next, the input gray-coded data is “10”.
Then, by referring to the created table, “11” is output as gray-decoded data.

(Regarding Differential Decoding Unit 15) Next, the differential decoding unit 15 will be described. To the differential decoding unit 15, differentially encoded 0/1 data is input. If the data bit input immediately before is D (pre) and the input data bit is D, the output data bit D (out) by differential decoding is

[Equation 14]

Is obtained. By repeating such an operation, differentially decoded data can be output.

(Example of Differential Decoding) First, assuming that the given initial data bit is 0, D (pre) = 0. When the input data bit D is D = 1, the output data bit D (out) becomes D (out) = 1. This completes the one-bit output.

Next, in the output of the second bit, since the data bit input immediately before (the first bit) is 1, D (pre) = 1, and the input data bit D becomes D (pre). = 1, the output data bit D (out) becomes D (out) = 0. Thus, differentially decoded data can be output.

[0096]

As described above, according to the present invention, a single receiving demapping device can obtain a demapping processing output corresponding to a plurality of modulation schemes. A desired output of the demapping process can be obtained by using it in an application handled by the terminal. In addition, since the modulation scheme that can perform the demapping process is switched by setting the parameter, it is possible to cope with a system in which the modulation scheme is switched for each time slot. Furthermore, when it is necessary to newly perform demapping processing of another modulation scheme,
A demapping process corresponding to a desired modulation method can be performed only by changing a parameter given as an argument to the demapping software without downloading new demapping software.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a reception demapping device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a PSK demodulation unit in the embodiment.

FIG. 3 is an 8-level PS for explaining a PSK demodulation unit;
Diagram showing signal point arrangement on phase plane in K

FIG. 4 is an 8-level PS for explaining a PSK demodulation unit;
The figure which shows a mode that a phase plane is divided into several areas in K

FIG. 5 is a diagram showing numbers indicating phase information on a phase plane for explaining a PSK demodulation unit;

FIG. 6 is an 8-level PS for explaining a PSK demodulation unit;
The figure which shows an example of the determination method of the signal point in K

FIG. 7 shows an 8-level PS for describing a PSK demodulation unit.
The figure which shows the other example of the determination method of the signal point in K.

FIG. 8 is a diagram showing an example of the contents of a table in FIG. 2;

FIG. 9 is a view showing another example of the contents of the table in FIG. 2;

FIG. 10 is a diagram showing a configuration of an FSK demodulation unit in the embodiment.

FIG. 11 is a diagram showing n angular velocities Ω plotted at equal intervals on a number line for explaining an FSK demodulation unit;

FIG. 12 is a diagram showing that an angular velocity Ω for describing an FSK demodulation unit exists in any of the regions divided by the determination boundary value.

FIG. 13 is a diagram showing numbers representing angular velocity information on a number line for explaining an FSK demodulation unit;

FIG. 14 is a diagram showing an example of the contents of a table in FIG. 10;

FIG. 15 is a view showing another example of the contents of the table in FIG. 10;

FIG. 16 is a diagram showing a configuration of a QAM demodulator in the embodiment.

FIG. 17 shows 16Q for describing a QAM demodulation unit.
Diagram showing signal point arrangement on phase plane in AM

FIG. 18 is a diagram showing an area divided for an in-phase component for explaining a QAM demodulation unit;

FIG. 19 is a diagram showing regions divided for orthogonal components for explaining a QAM demodulation unit;

FIG. 20 is a diagram illustrating numbers assigned to orthogonal components for describing a QAM demodulation unit;

FIG. 21 is a diagram showing numbers assigned to in-phase components for describing a QAM demodulation unit.

FIG. 22 is a view showing another example of the contents of the table in FIG. 16;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Digital modulation signal input terminal 2 ... Digital signal processing unit 3 ... Program memory 4 ... Parameter input unit 5 ... Parameter 6 ... Symbol value output terminal 10 ... Demodulation unit 11 ... PSK demodulation unit 12 ... FSK demodulation unit 13 ... QAM Demodulation unit 21 PSK signal input terminal 22 Signal point determination unit 23 Table reference unit 24 Table 25 Symbol value output terminal 31 FSK signal input terminal 32 Input buffer 33 Angular velocity determination unit 34 Reference table Unit 35: Table 41: Input terminal of QAM signal 42: Signal point determination unit 43: Table reference unit 44: Table 45: Output terminal of symbol value

Claims (6)

[Claims] 1. A receiving demapping apparatus for performing a demapping process of generating a symbol value of an original data sequence from a received digital modulation signal modulated by an arbitrary one of a plurality of predetermined modulation methods. A parameter input unit for inputting a parameter for the demapping process corresponding to a modulation scheme of the reception digital modulation signal; and a parameter input unit configured to be compatible with the plurality of modulation schemes, and converting the reception digital modulation signal according to the parameter. A reception unit comprising: a demodulation unit that demodulates in a demodulation system corresponding to a modulation system of the digital modulation signal; and at least one decoding unit that decodes an output signal from the demodulation unit according to the parameter. Mapping device. 2. A reception demapping apparatus for performing a demapping process of reproducing a symbol value of an original data sequence from a digital modulation signal modulated by an arbitrary one of a plurality of predetermined modulation systems. A digital signal processing unit that generates the symbol value from the received digital modulation signal by digital signal processing in accordance with pre-loaded software for the demapping processing; and the demapping corresponding to a modulation scheme of the digital modulation signal. A parameter input unit for inputting parameters for processing to the digital signal processing unit as arguments to the software. 3. The parameter input unit includes: a type of the modulation scheme, a multi-level modulation number, a modulation index when the modulation scheme is frequency modulation, and a phase offset when the modulation scheme is phase modulation. 2. The reception demapping device according to claim 1, wherein information specifying ON / OFF of gray decoding and ON / OFF of differential decoding is input as the parameter. 4. The demodulation section determines a signal point on a phase plane based on in-phase component data and quadrature component data of the received digital modulation signal in accordance with a modulation multi-level number and a phase offset given as the parameters. The signal point determination unit, a table storing the correspondence between the phase information of the phase-modulated digital modulation signal and the symbol value, and the symbol value by referring to the table based on the output of the signal point determination unit. 2. The reception demapping device according to claim 1, further comprising a phase demodulation unit including a table reference unit to be obtained. 5. An input buffer for storing a required number of samples of in-phase component data and quadrature component data of the received digital modulation signal according to the modulation multi-level number and the modulation index given as the demodulation parameters. An angular velocity determination unit that determines an angular velocity based on the output of the input buffer, and a table that stores the correspondence between the angular velocity information and the symbol value of the frequency-modulated digital modulation signal,
2. A frequency demodulation unit comprising a table reference unit for obtaining a symbol value by referring to the table based on an output of the angular velocity determination unit.
The receiving demapping device according to the above. 6. The signal point for judging a signal point on a phase plane based on in-phase component data and quadrature component data of the received digital modulation signal according to a modulation multi-level number given as the demodulation parameter. A determination unit, a table storing the correspondence between the amplitude and phase information of the quadrature amplitude-modulated digitally modulated signal and the symbol value, and the symbol value by referring to the table based on the output of the signal point determination unit. 2. The reception demapping device according to claim 1, further comprising a quadrature amplitude demodulation unit including a table reference unit to be obtained.