JPS60254952A - Decision system for received signal - Google Patents

Abstract

PURPOSE:To reduce the scale of a table to be retrieved on the basis of coordinates of a received signal point as much as possible by allowing a modem in a communication system to decide that a received signal point corresponding to a transmitted signal point in a division area is a real received signal point. CONSTITUTION:A demodulating circuit 53 demodulates a received wave to output X and Y coordinate data on the received signal point corresponding to the received wave, and further an equalizing circuit 54 outputs new X and Y coordinate data from the demodulating circuit 53 by correcting the influence of strain, etc., upon the X and Y coordinate data. Then, it is decided on the basis of the absolute values of the X and Y coordinate values which of areas A-1, A-2, A-3, and A-4 the received signal point is in. Individual processing is performed for every area after said decision making, and a decision on the division area where a received signal represented by the absolute value coordinates belongs is made. Finally, it is decided that the received signal corresponding to a transmitted signal point in a division area whose quadrant is determined is a real received signal point.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a received signal discrimination method when demodulating a received signal in a modulator/demodulator in a communication system.

[Technical background] For example, a CPU 10 and a terminal device 40 as shown in FIG.
(hereinafter referred to as DTE 40), there is a modem 20, 30 (hereinafter referred to as modem 20, 30) which is composed of modulators 20a, 30a and demodulators 20b, 30b on the CPU 10 side and DTE 40 side, respectively. ), and information from the CPU 10 or DTE 40 is provided.
Based on the information from the modulators 20a and 30a, the modulators 20a and 30a modulate carrier waves, for example, amplitude and phase modulate them, and transmit them to the DTE 40 side or the CPU 10 side, and the received waves are transmitted to the harmonics 30a and 30a.
20a demodulates and uses the demodulated information to send the CPU 1
0 or information from DTE40 to DTE4
0 or CP tJ 10 is recognized.

By the way, when information from CPLllo or DTE40 is output at 9600 bits/second, which is the general high-speed mode, the modulation rate specified in the communication line is 2.
Since the frequency is 400 times/second, it is output as 4-bit parallel data, and in this case, there are 16 types of information, that is, modulation information. Therefore, on the transmitting side, there is a
6 transmission signal points are arranged, and on the receiving side, for example, the second
As shown in the figure, reception signal points P corresponding to the transmission signal points defined on the reception side are arranged. Here, the received signal point P1 is, for example, the X position 1! Amplitude information is expressed by IX1, and phase information is expressed by angle θ1 formed between the X axis and OP1.

In such a communication system, for example, a carrier wave modulated based on modulation information expressed by a transmission signal point corresponding to reception signal point P1 is distorted within the line, and the carrier wave (reception wave) is changed to the reception signal point on the reception side. When the received signal point P2 is demodulated as P2, it must be determined that the received signal point P2 should originally be the same as the received signal point P1. Therefore, the reception plane is divided into divided areas E (determination plane) corresponding to the transmission signal points,
For example, all received signal points within divided area E1 are received signal points P
It is necessary to have a method for determining the received signal such that it is determined as 1.
Furthermore, in realizing a communication system in which high-speed data transfer, for example, 1'4400 bits/second, the receiving signal point and the transmitting signal point are 128 points or 256 points as shown in Fig. 3. , it is desired that the above determination method be more efficient.

[Prior art and problems] The simplest method of this kind is to
For example, if we consider that each of the coordinate values X and Y of a received signal point is expressed as a numerical value of 4 pips]-, the received signal point on the reception plane will be 1024 in total, considering its positive and negative regions. Therefore, for each of these 1024 received signal points, a table is provided in which the number of the divided area E to which the received signal point belongs is assigned, and based on the received signal points obtained by demodulation, The above table is searched to determine the divided area E to which the received signal point belongs, and the received signal point corresponding to the transmitted signal point within this divided area E is determined to be the true received signal point.

However, in order to realize such a determination method, it is necessary to provide a ROM table that shows the correspondence between received signal points and divided areas E. X, Y representing signal points
Since the coordinate value has a total of 10 bits including its positive/negative information, it becomes a 10-bit input, and the contents are also 1024 (bytes), resulting in a problem that the size of the ROM table becomes extremely large. be.

[Object of the Invention] The present invention has been made in view of the above, and an object of the present invention is to provide a received signal determination method that minimizes the size of a table to be searched based on coordinate values representing received signal points. The purpose is

[Structure of the Invention] In order to achieve the above object, the present invention determines carrier wave modulation information based on a transmission signal point represented by a point on a transmission plane defined on the transmission side, and determines carrier wave modulation information based on this modulation information. The modulation information of the received wave modulated and transferred at the receiving side is demodulated as a received signal point expressed by a point on the receiving plane corresponding to the above-mentioned transmitting plane specified on the receiving side. Received signal demodulated corresponding to received wave.

A received signal determination method that determines a true received signal point corresponding to a transmitted signal point indicating modulation information on the transmitting side based on a predetermined area on a receiving plane that is an orthogonal coordinate system. As shown in FIG. 4, the area is divided into mxn (n2m) divided area groups corresponding to the transmission signal points at the same pitch l in both directions of the orthogonal coordinate axes (X-axis, Y-axis), and Two orthogonal wheels in the area (X axis, Y axis)
From the divided area including the received signal point expressed by the origin coordinates (S, S') and located at the corner of the divided area group, to each divided area of the divided area group, either of the two orthogonal wheels. Numbers forming an arithmetic progression of a predetermined initial value p and a predetermined intersection q are sequentially assigned in one axis direction, for example, in the same direction as the Y-axis direction, while the number of area divisions N in this number assignment direction (Y-axis direction) is
(=m), the above initial value p, and the tolerance q, from the starting point coordinate value S in the orthogonal coordinate system to the above section pitch l.
coordinate values belonging to the same section (for example, S to S+, /
.

(p+ 1-q-N) values (i=0.
1.2-, n-1) is provided in the same direction as the numbering direction of the -E division area of the received signal demodulated corresponding to the actual received wave. Search the above table based on the coordinate value on the axis (Y axis) to find (p + 1-a-N > value, and then from this search value (p+ 1-(1-N)) Subtract the initial value p of the assigned number (1-q-N), divide it by the N value, calculate the value, and calculate the coordinate value of the received signal point on the other axis (X-axis). Search the above daple based on (0+j-q-N) value (j=0.1゜2
,...n-1), and set as above ( i-q
) la and the (p + j-q-N) value, and the received signal point is in the divided region assigned the same number as the (p+q・(i + j-N)) value obtained by adding the (p + j-q-N) value. It is determined that the received signal point exists, and the received signal point corresponding to the transmitted signal point within this divided area is determined as the true received signal point.

In FIG. 4, even if the numbering direction of the divided regions is the same as the X-axis direction, the structure of the present invention does not change, and the above N value becomes N-n. Further, the situation does not change even if the Y-axis direction is divided into n divisions and the X-axis direction is divided into m divisions. Furthermore, when the axial directions of the X-axis and Y-axis are changed, the divided region to which the initial value should be assigned is determined to be one of the divided regions located in the squares of the divided region group as the position of the starting point coordinate changes.

[Function] For example, in the examples shown in Figs. 4 and 5,
If the coordinates are in the range (S+J!+1) to (S+2J) and the Y coordinate is in the range (8+22+1) to (S+3)), search the table shown in Figure 5 based on the X coordinate value. (p+m-q) value and search the table based on the Y coordinate to find (p+2-m-
q) Ia, and further this search value (p+2・m−q
) minus the initial value p (2・m−c+), divided by m to find the (2・q) value, and calculated as above (p +
(p+
It is determined that the received signal point exists within the divided region assigned the same number as the (m+2)·q) value.

[Embodiments of the invention] Embodiments of the present invention will be described below based on the drawings.

FIG. 6 is a block diagram showing the basic configuration of an example of a demodulator that employs the received signal determination method according to the present invention. In this example, receiving signal points corresponding to 128 transmitting signal points as shown in Fig. 3 are arranged on the receiving plane -F defined on the receiving side, and the X and Y coordinates of the receiving signal points are The data is 4
It is expressed as bit data (0, 1, . . . , E, F) (positive/negative information is not included).

In FIG. 6, for example, a modulated carrier wave is input from the CPU to an input port 51 via a line, and a received wave input to this input port 51 is input to a demodulation circuit 53 via an A/D conversion circuit 52. ing. And demodulation circuit 5
3 demodulates the received wave and outputs the X and Y coordinate data of the received signal point corresponding to the received wave, and furthermore, the equalization circuit 54 performs distortion etc. on the X and Y coordinate data from the demodulation circuit 53. The new X, Y coordinate data is output after correction for the influence of On the other hand, 55 is a ROM table for data retrieval based on each of the X and Y coordinate data from the equalization circuit 54 as will be described later, and 56 is a ROM table for storing a search value Rx of the ROM table 55 based on the X coordinate data. The data register 57 is composed of a register and a register that stores the search value Ry of the ROM table 55 based on the above Y coordinate data, as will be described later. This is a calculation unit that performs predetermined calculations based on the information. Then, the calculation section 57
The coded data obtained by searching the code conversion table 58 based on this information is sent to the DTE4, for example, through the output port 59.
I am trying to output it to 0. Note that 50 is a processor that controls the entire system.

Here, as shown in FIG. 7, the receiving plane defined on the receiving side is within ±7) of each coordinate axis.

(A-1) in each quadrant with (±8) as the boundary.

It is divided into areas (A-2), (A-3), and (A-4). As shown in FIG. 8, which shows the first quadrant, each quadrant has the same bits in both directions of the X and Y coordinate axes for the <A-1) region. -2, it is divided into 4×4 divided area groups corresponding to the transmission signal points, includes the reception signal point expressed by the origin coordinates (0, O) of the X, Y coordinate axes, and the corners of the divided area group are From the divided area located at , for each divided area, initial value p-0 and intersection q =
Numbers forming an arithmetic progression of 1 are sequentially assigned (the assigned numbers are expressed in hexadecimal). For the (A-2) area, the X-axis direction corresponds to the transmission signal point with the coordinate value 9. By dividing the Y-axis direction at pitch no = 2 during A, it is divided into 8 divided area groups, and each divided area is divided from the side touching the (A-1) area to the final area of the (A-1) area. Following the assigned number (OF>), numbers that form an arithmetic progression with a tolerance of q=1 are sequentially assigned in the same direction as the Y-axis direction.Also, for the (A-3) area, it corresponds to the transmission signal point. and the X-axis direction is pitch=
2, set the Y-axis direction to the coordinate value 9. By partitioning between A, it is partitioned into eight divided area groups, and each divided area is divided into (A
-1) Following the final assigned number (17) of the area (A-2) above from the side that is in contact with the area, numbers that form an arithmetic progression with a tolerance q-1 are sequentially assigned in the same direction as the X-axis direction. There is.

Furthermore, the area (A-4) is divided into a divided area where the coordinate value X≧Y and a divided area where the coordinate value X<Y. Assigned number (1
The same number as 7) is given, and the same number as the last given number (1F) in the area (A-3) is given to the divided area where X<Y.

On the other hand, the specific contents of the ROM table 55 are the first table shown in FIG. 9, the second table shown in FIG.
The first table contains the origin coordinate values (
0) to the coordinate values belonging to the same section for each section pitch mini 2, in order from the section containing the origin coordinate value (0) (
p+1-a-N) values, i.e. p=o, q=1. N
=4 to (O+4·i) values (i=0.1, 2.3), and the second table is 10'' for the coordinate value 8.9.

14'' is assigned to the coordinate values A to F.

Next, the operation will be explained.

The basic flow of operation is as shown in the flowchart shown in FIG.

First, X of the received signal point corresponding to the actual received wave.

The quadrant information to which this received signal point belongs is determined from the Y coordinate output (equalized output) based on the positive and negative bits of the X and Y coordinate outputs, and the absolute values of the X and Y coordinate values are divided. still,
This absolute value 3] calculation is only used to limit the target reception plane to the first quadrant shown in FIG.

Next, based on the absolute values of the X and Y coordinate values, the received signal points are (A-1'), (Δ-2>, (A-3), (A-
4) Determine to which region it belongs. Specifically, since the above absolute value is expressed in 4 bits, the 4 bits
Q II, II of the most significant bit MSB of bit data
The break at the coordinate value 7.8 is determined by the 11I determination. In this way, after determining the areas (8-1) to (A-4>), individual processing as described later is performed for each area, and the received signal expressed by the absolute value coordinates belongs. The divided areas (see FIG. 8) are determined.

Then, based on the quadrant information obtained at the beginning, it is determined to which quadrant the divided area determined by the above J: sea urchin belongs, and the reception corresponding to the transmission signal point within the divided area whose quadrant is finally determined is determined. Determine the signal as a true received signal point.

Next, individual processing in the above regions (A-1) to (Δ4) will be explained.

(1) A-1 area■ Search the first table (Fig. 9) based on the X coordinate value (absolute value, the same applies hereinafter) of the received signal point, and find the search value RX
is stored in the data register 56.

(2) Search the first table based on the Y coordinate value (absolute value, the same applies hereinafter) of the received signal point, and store the search value Ry in the data register 56.

■ The search value Ry stored in the data register 56 is computed by Ry/4 to create a new RV (Ry←R
y/4).

(2) Determine the divided area assigned the same number as the value obtained by adding the search value Rx and the new Ry.

For example, if the received signal point is (4, 6>), RX=08.
Ry=OC, and 08+OC/4=OB, and the divided area to which the received signal point (4, 6> belongs) is determined to be the divided area assigned the number OB.

(2> A-2 area ■ Based on the X coordinate value of the received signal point, create the second table (first
0 figure), and the search value RX is stored in the data register 56.
Store in.

(2) Search the first table based on the Y coordinate value of the received signal point, and store the search value RV in the data register 56.

■ Performs the operation Ry /4 on the search value RV stored in the data register 56 and sets it as a new R (Ry (-R
y/4).

(2) Determine the divided area assigned the same number as the value obtained by adding the search value RX and the new RY.

For example, if the received signal point is (8,3), RX=10.
R=04, 10+04/4=11, and the 90% area to which the received signal point (8, 3) belongs is determined to be the area numbered 11.

(3) Area A-3 ■ Search the first table based on the X coordinate value of the received signal point, and store the search value Rx in the data register.

It is stored in the star 56.

(2) Search the second table based on the Y coordinate value of the received signal point, and store the search value Ry in the data register 56;

■ Add 08 to the search value Ry stored in the data register 56 to create a new Ry (Ry←Ry+08>).

■ Store it in the data register 56 and perform the calculation of RX/4 on the search value Rx to create a new RX (Rx
4-Rx/4).

(2) Determine the divided area assigned the same number as the value obtained by adding the newly determined RX and Ry as described above.

For example, if the received signal point is (4, 9>), R x = 08, R
y-10, 10+8+08/4=IA, and the divided area to which the received signal point (4, 9) belongs is determined to be the divided area assigned the number 1A.

(4) Area A-4 ■ Compare the X and Y coordinate values of the received signal point.

■ When X≧Y, the divided area numbered 17 is determined.

■ When X<Y, determine the divided area numbered 1F.

As described above, according to the present embodiment, by using the 4-bit input ROM table 55 having a small size of 16 bytes, it is possible to determine the reception signal points corresponding to the 128 transmission signal points. In addition, the only operations that can be realized in the determination process are addition and division by 4°', which can be performed by 2-bit shift operations.
Its processing is also easy.

[Effects of the Invention] As explained above, according to the present invention, a predetermined area on the reception plane is arranged at the same pitch in both directions of the orthogonal coordinate axes, and mxn (n≧m) corresponding to the transmission signal point is Conventionally, when determining the divided area to which the received signal point corresponding to the received wave belongs, for example, m
What used to require a byte table can now be simply an n-byte table, making it possible to make the relevant determination by simply using a smaller table.

In addition, in the present invention, as the number of transmission signal points in the same area increases,
That is, it is effective in communication systems where data transfer is faster.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the basic configuration of the communication system, Figure 2 is an explanatory diagram showing an example of reception signal points corresponding to transmission signal points on the reception plane defined on the reception side, and Figure 3 is an illustration of 128 points. FIG. 4 is an explanatory diagram showing an example of the arrangement of received signal points, FIG. 4 is an explanatory diagram showing more generally the state of numbering divided areas in the received signal determination method according to the present invention, and FIG. 5 is an explanatory diagram according to the present invention. An explanatory diagram more generally showing the state of the table in the received signal determination method, FIG. 6 is a block diagram showing the basic configuration of an example of a demodulator that employs the received signal determination method according to the present invention, and FIG. An explanatory diagram showing the state of plane area division,
FIG. 8 is an example in which the first quadrant of the reception plane is divided into divided regions corresponding to transmission signal points. FIGS. 9 and 10 are explanatory diagrams showing an example of numbering divided areas, and FIGS. 9 and 10 are explanatory diagrams showing tables to be provided corresponding to the divided area group shown in FIG. 8. FIG. 3 is a flowchart showing the flow of received signal determination operation in the device. 50... Processor, 51... Input port, 52...
...A/D conversion circuit, 53...Demodulation circuit, 54...
Equalization circuit, 55...ROM table 56...Data register, 57...Arithmetic unit, 58...Dipple for code conversion, 59...Output port. Patent applicant Fujitsu Ltd.
Patent attorney Koji Matsuoka has published Figure 1 [Figure 2, Figure 8, Figure 9, Figure 10, Figure 11]

Claims (1)

[Claims] The modulation information of the carrier wave is determined based on the transmission signal point expressed by the point on the transmission plane specified on the transmitting side, and the modulation information of the received wave on the receiving side is modulated based on this modulation information and transferred. , while demodulating as a received signal point expressed by a point on the receiving plane corresponding to the above-mentioned transmitting plane defined by the receiving side, the vf
L? This is a received signal determination method that determines the true received signal point corresponding to the transmitted signal point indicating modulation information on the transmitting side based on the received signal point A, and the received signal point is a rectangular coordinate system. A predetermined area on a plane is divided into a group of m×n (n≧m) divided areas corresponding to the transmission signal point at the same pitch in both directions of the orthogonal coordinate axes, and the origin coordinates of the two orthogonal axes in the predetermined area are A predetermined direction is set in the same direction as one of the two orthogonal axes from a divided area including the expressed reception signal point and located at a corner of the divided area group to each divided area of the divided area group. While sequentially assigning numbers that are an arithmetic progression of the initial value p and the predetermined tolerance q,
Based on the number of area divisions N (N=m or n) in the numbering direction and the above initial value p1 tolerance q, from the starting point coordinate value in the orthogonal coordinate system to the coordinate value belonging to each same section for each section pitch, Then, (p+1-a-N) (direct(i = O, i, 2
．． -, n-1) is provided, and the table is calculated based on the coordinate values of the received signal point demodulated corresponding to the actual received wave on the axis that is in the same direction as the numbering direction of the divided area. Search for (p + 1-q-N
) value, and then this search value (p + 1-q-N >
Subtract the initial value p of the number assigned to the divided area from Search the above table based on the coordinate value of the input (1) + j−q−
N ) value (j=o, 1.2..., n-1), and the (i-q) value obtained as above and (p 4- j-a
−N ) value (p+q・(i+j
-N)) It is determined that the received signal point exists within the divided area assigned the same number as the value, and the received signal point corresponding to the transmitted signal point within this divided area is set as the true received signal point. A received signal determination method is characterized in that the received signal determination method is characterized in that the determination is made as follows.