JPH0621985A - Method and device for generating reliability information - Google Patents

Abstract

PURPOSE:To improve the accuracy of the reliability information by making a use of the present reception information and the reception information before one in computing the reliability information on a reception level. CONSTITUTION:In the method generating the reliability information, a delay detection device 13 obtains the common mode and orthogonal component by multiplying the reception level in the specified time and the reception level in the time by the prescribed time before the specified time of the reception signal to be inputted, and a discrimination and reliability generation circuit 15 generates the binary discrimination value and the reliability based on it. The generation of the reliability information is performed by multiplying the multiplication value by a multiplier means 5 multiplying the reception level of a time measured by a measurement means 1 measuring the reception level in the prescribed timing and the reception level in the time by the prescribed time before the corresponding time and the output of the circuit 15 by means of multiplier circuits 7 and 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a receiving system using a limiter and a differential detector, and more particularly to a reliability information generating method and apparatus used in a diversity receiving system and soft decision decoding of error correcting codes.

[0002]

2. Description of the Related Art A conventional reliability information generating apparatus will be described with reference to FIG. The delay detector 113 includes a limiter 111.
The distance between the signal and the determination boundary obtained by detecting the received wave input via is output. The smaller this distance is, the closer the detected signal is to the judgment boundary, that is, the reliability of the judgment is smaller. Conversely, the greater the distance, the greater the distance from the determination boundary and the higher the reliability of the determination value.
Here, for simplicity of explanation, this distance is referred to as reliability information related to the phase.

On the other hand, the reception level measuring circuit 101 outputs the envelope level of the reception waveform. The obtained envelope level is squared by the squaring circuit 105 to obtain a power dimension value. This power value is referred to as reliability information related to the reception level. The reliability information of the decoded symbol is obtained by multiplying the reliability information related to the phase and the reliability information related to the reception level by the multiplication circuit 1.
Multiply by 07 to obtain.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The product of the current reception information and the reception information immediately before is taken, the obtained value d is predetermined and the area of the symbol determination is compared, and the symbol in the area including d is estimated to be the closest to the transmission symbol, This is determined as a decoded symbol. Since both the current reception information and the reception information immediately before are used for the determination of the decoded symbol, it is natural to use these information also in the calculation of the reliability information of this decoded symbol.

However, in the conventional reliability information generating apparatus, the reliability information regarding the phase is obtained by using both the present and previous reception information, but the reliability information regarding the reception level is the current reception information. It was only used.

The present invention has been made in view of the above problems, and improves the accuracy of reliability information by using the current reception information and the reception information immediately before the current one in the calculation of the reliability information regarding the reception level. It is an object of the present invention to provide a reliability information generating method and an apparatus therefor.

[0007]

To achieve the above object, the first invention of the present application is to provide a reception level of an input reception signal at a certain specified time and a reception level at a time before the specified time by a predetermined time. From the multiplication result with the reception level,
The gist is to generate the reliability of the information symbol obtained by decoding the received signal.

The second invention of the present application is a reliability information generating apparatus for generating the reliability of an information symbol obtained by decoding a received signal, and measuring means for measuring the received level of the received signal at a predetermined timing. A multiplying unit that multiplies a reception level at a certain specified time measured by the measuring unit and a reception level at a time that is a predetermined time before the specific time, and a multiplication value obtained by the multiplying unit. The gist of the present invention is to have a reliability generation means for generating reliability of an information symbol obtained by decoding the received signal.

[0009]

In the reliability information generating method according to the first aspect of the present invention, the result of multiplication of the reception level of the reception signal at a certain specified time and the reception level of the reception signal at a predetermined time before the specific time is obtained. And the reliability of the information symbol obtained by decoding the received signal is generated from this multiplication result.

A reliability information generating apparatus according to the second invention of the present application is
By the measuring means for measuring the reception level of the reception signal at a predetermined timing, the reception level of the reception signal at a certain specified time and the reception level of the reception signal at a predetermined time before the specific time are measured, Based on the multiplication value obtained by multiplying the measured plurality of reception levels by the multiplication means, the reliability of the received signal is generated by the reliability generation means to generate the reliability of the information symbol.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a reliability information generating device according to the present invention.

First, referring to FIG. 1, the schematic configuration of the reliability information generating apparatus of the present embodiment is such that a reliability level generating system and a phase reliability system are used. It is roughly classified into a system that generates the reliability of a decoded symbol obtained by decoding a received wave from the reliability generated in one system. First, the configuration of the system that generates the reliability regarding the reception level will be described. This system measures an envelope level of an input received wave, and specifically, a received level measuring circuit 1 using a low-pass filter, and an input received wave connected to the receiving level measuring circuit 1. Is delayed by one symbol time and the reception level R1 one symbol before is delayed.
A 1-symbol time delay circuit 3 for outputting
The reception level R1 of one symbol before output from the 1-symbol time delay circuit 3 and the reception level R0 of the current reception wave output from the reception level measuring circuit 1 are multiplied to output reliability information about the reception level. Multiplication circuit 5
Composed by.

Here, one symbol has 2 bits in 4-level PSK transmission and 3 bits in 8-level PSK transmission. Further, one symbol time is a time interval of symbols, and in the case of 9,600 bps transmission of 4-level PSK, it is 1 /
(9,600 / 2) second is one symbol time.

Further, the system for generating the reliability regarding the phase includes a limiter 11 for removing the upper part and the lower part of the input received wave based on predetermined reference voltages, for example, x (t
-2), x (t-1), x (t), x (t + 1), x
When there is an input of (t + 2), x (t−1) × x
(T) is calculated, and the in-phase component id is obtained from the obtained multiplication value.
The differential detector 13 that obtains the em and the quadrature component qdem, and the binary judgment values (idec and qdec) based on these two components.
And a determination and reliability generation circuit 15 for generating reliability.

Further, the system for generating the reliability of the decoded symbol includes a multiplication circuit 7 for calculating a multiplication value of the reliability information about the reception level output from the multiplication circuit 5 and the reliability ipr regarding the phase of idec, The multiplication circuit 9 calculates a multiplication value of the reliability information about the reception level output from the multiplication circuit 5 and the reliability qpr about the phase of qdec.

Next, the operation of this embodiment will be described. In addition,
In this embodiment, it is assumed that QPSK modulation is used as the modulation method.

First, the differential detection of π / 4QPSK modulation will be described. The product of the current reception information and the reception information immediately before is taken, and from this product, the in-phase component idem and the quadrature component qd
get em. Binary determination of "1" or "0" is performed for each of the idem and qdem. Each 2
The value judgment values (idec and qdec) are compared with a predetermined threshold value t and the magnitude of each component, and the result is determined to be "1" or "0".

The reliability ip of the phase of the idec
The reliability qpr regarding the phase of r and qdec is ipr = | idem-t | qpr = | qdem-t |.

On the other hand, the reliability regarding the reception level is obtained as follows. Here, the current received wave level is set to R0
And the received wave level one symbol before is R1. R0
The value R0 * R1 obtained by multiplying R1 and R1 is used as reliability information regarding the reception level. The reliability information ir and qr regarding idec and qdec are calculated as follows.

Ir = ipr * R0 * R1 qr = qpr * R0 * R1 As described above, the product of the previous reception level and the current reception level is used for the calculation of the reliability information. The accuracy can be improved.

In the above embodiments, the reception level measuring instrument 1 outputs the true value of the envelope value of the reception waveform. However, when actually configured, the reception level measuring device 1 may output the logarithmic value of the envelope of the reception waveform. In this case, in order to realize the processing equivalent to the multiplication of the true value output, the sum of the logarithmic outputs is taken and the next obtained sum of the logarithmic outputs is returned to the true value. After this, the same processing as in the above embodiment can be performed.

As described above, according to the present invention, the accuracy of the reliability information can be improved by using the received information at the present time and the reception information immediately before for the calculation of the reliability of the amplitude. By using this reliability information, the characteristics of the diversity receiver and soft decision decoder are improved. For example, when a combination with diversity as shown in FIG. 2 was simulated, a result was obtained in which the characteristics of the receiver were improved up to about 0.5 dB at the average reception level as compared with the conventional method.

In FIG. 2, the first block 21
A and the second block 21B incorporate the reliability information generating apparatus shown in FIG. 1, and these first block 21A
And reliability information output from the second block 21B, respectively, are compared by comparators 23A and 23B, and a selector 25A,
The signal selection in 25B is controlled.

[0024]

As described above, the reliability information generating method and the apparatus thereof according to the present invention calculates the reliability information about the reception level by using the reception information of the present and the immediately preceding reception information. Therefore, the accuracy of the reliability information is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment according to the present invention.

FIG. 2 is a block diagram showing an example in which the present invention is applied to a diversity receiver.

FIG. 3 is a block diagram showing a schematic configuration of a conventional example.

[Explanation of symbols]

 1 reception level measurement circuit 3 1 symbol time delay circuit 5 multiplication circuit 7 multiplication circuit 9 multiplication circuit 11 limiter 13 delay detector 15 judgment and reliability generation circuit 21 block 23 comparator 25 selector

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazunaga Ikeda 1-1-6 Uchisaiwai-cho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Inventor Taketaro Iketo 1-1-1 Uchisai-cho, Chiyoda-ku No. 6 Nippon Telegraph and Telephone Corporation

Claims (2)

[Claims] 1. The reception signal is obtained by decoding the reception level of an input reception signal at a certain specified time and the reception level at a time before the specific time by a predetermined time. A reliability information generation method characterized by generating reliability of an information symbol. 2. A reliability information generating apparatus for generating the reliability of an information symbol obtained by decoding a received signal, and measuring means for measuring the received level of the received signal at a predetermined timing, and the measuring means. Multiplying means for multiplying the reception level at a certain specified time by the reception level at a predetermined time before the specific time, and the received signal based on the multiplication value obtained by this multiplication means. A reliability information generating device, comprising: reliability generating means for generating reliability of an information symbol obtained by decoding.