JP3209596B2 - Data communication device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication apparatus employing a spread spectrum system, and more particularly to an improvement in a data error detection method.

[0002]

2. Description of the Related Art In conventional data communication, in order to know a data error, a method of inserting a CRC code or the like into transmission data and transmitting the data has been employed to detect the error.

[0003]

However, such a conventional method has a drawback that even if the communication environment is good, the effective transmission rate is deteriorated because an error detection code is inserted. An object of the present invention is to measure a communication environment,
The purpose is to reduce the error by controlling the superposition of the error detection code and the transmission rate on the transmitting side based on the measurement data.

[0004]

In order to achieve the above object, test data used for measuring a communication environment is provided.
A transmitter having a function of transmitting
Based on the received signal power level and the received signal and spreading code
And the level of the correlation peak signal obtained by the correlation operation with
Communication data to obtain data about the communication environment by comparing
Data measurement means and the data on the communication environment.
And send a data rate based on the data.
Means for determining; and a receiver comprising:
The environmental data measuring means receives the test data based on the test data.
A mixer circuit for squaring the signal and converting it to a DC signal;
Low-pass fill to cut signals other than DC from C signal
And the DC signal from the low-pass filter
Quantization circuit that performs analog-to-digital conversion to obtain power of a received signal
And a correlation peak signal.
And a correlation peak signal from the detected signal
Detector that detects the peak of the
A / D conversion of the signal to obtain the level of the correlation peak signal
The power of the received signal and the level of the correlation peak signal.
And a comparator for calculating the ratio to the bell.
You.

[0005]

[0006]

In the device of the present invention, the communication environment is measured based on test data from the transmitting side, and the data rate and the like are controlled based on the measured data. The measurement of the communication environment is performed, for example, by comparing the power level of the received signal based on the test data with the level of the correlation peak signal.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments shown in the drawings. FIG. 1 shows an embodiment of a transceiver according to the present invention which varies a data rate according to a communication environment. In the figure, R is a receiving unit, T is a transmitting unit, and DET is a D / U measuring unit. In the receiving unit R, 1, 2, 3 are amplifiers, 4 and 5 are band pass filters (BPF), 6 is a convolver,
7 is a mixer, 8 is a PN code generator (PNG), 9 is a carrier signal generator, 10 is a data demodulator, and 11 is a data processing circuit. In the transmission unit T, 12 is a data buffer, 13 is a communication environment system, 14 and 16 are mixers,
17 is a carrier signal generator, 18 is an amplifier, 19 is BP
F.

The D / U measurement unit DET includes a reception power measurement circuit DET1 including an amplifier 20, a mixer 21, a low-pass filter (LPF) 22, and a quantization circuit 23, and a detector 2
4, a peak detection unit DET2 including an amplifier 25, a peak detector 26, and a quantization circuit 27, and a comparator 28. 29 is a transmitting / receiving antenna, and 30 is a directional coupler.

In the transceiver shown in FIG. 1, a transmitted signal is received by an antenna 29, passed through amplifiers 1, 2 and a BPF 4, one is input to a convolver 6, and the other is input to a power measurement circuit DET1 for a received signal. I do. In Convolva,
A correlation between the received signal and a reference signal obtained by carrier-modulating a spread code generated from PNG8 is performed. When the received signal and the reference signal match, the convolver 6 outputs a sharp correlation peak. The signal output from the convolver passes through the amplifier 3 and the BPF 5, and is sent to the data demodulation unit 10 and the peak detection unit DET2. Data demodulation unit 10
In, data demodulation is performed based on the correlation peak.

The signal received by the reception power measurement circuit DET1 is first amplified by the amplifier 20 to a certain level so that post-processing is easy. The amplified signal is
The signal is squared by the mixer 21 and converted into a DC signal. Next, signals other than the DC component are cut by the LPF 22 and sent to the quantization circuit 23. The quantization circuit 23 samples the level of the DC signal, performs A / D conversion, integrates the processing time τ of the convolver 6, and obtains the power of the received signal.
At this time, the power PU is:

[0011]

(Equation 1)

## EQU1 ## Here, n is the amplitude of the noise, s is the amplitude of the spread signal, and h is the amplitude of the combined component of the noise and the spread signal. However, when n≫S (D / U <0), the PU becomes h ≒ n, indicating the power of noise.

Next, the convolver output from the peak detector DET2 is sent to the peak detector 26 via the detector 24. The peak detector 26 detects the position with the highest level from the correlation peak signal output from the convolver 6, and performs A / D conversion in the next quantization circuit 27. Here, the level of the correlation peak signal output from the convolver 6 is

[0014]

(Equation 2)

## EQU1 ##

Therefore, in the comparator 28, this PU and PD
By comparing these values, the D / U ratio at that time can be obtained. Since the D / U ratio at which data starts to be erroneous can be theoretically determined, when the value is k and the PD / PU ratio k becomes below, a signal from the comparator is transmitted to the communication environment system 13 on the transmission side. The transmission and error correction code are added, or the transmission data rate is reduced to improve the communication state. Conversely, when the PD / PU ratio is high, no error correction code is added. Also, the transmission data rate is increased to perform high-speed communication.

In the operation of the communication environment system 13 on the receiving side, first, it is known from the signal from the data processing circuit 11 that the data is test data. At this time, the optimum data rate is determined based on the signal from the D / U measurement unit DET (for example, when the data rate is T, T = k × D / U may be used). Then, a signal indicating the data rate is sent to the data buffer 12. The data rate at this time is the same as that of the transmitting side and is a low data clock. The operation of the communication environment system 13 on the transmission side receives communication environment data from the data processing circuit 11 and sets a data clock based on the communication environment data.

FIG. 2 is a flowchart showing the operation of transmitting and receiving signals and the data processing between the receiving side Rx of the transceiver of FIG. 1 and the transmitting side Tx of another transceiver, and FIG. This shows the time lapse of the transfer of the data.

In FIG. 2, at step ST1, the transmitting side T
x transmits test data for checking the communication environment to the receiving side. In step ST2, the receiving side Rx obtains PD / PU based on the test data signal, and detects in step ST3 whether or not the value is equal to or larger than a predetermined value k. In step ST4, the communication data rate is determined based on the obtained PD / PU. Next, in step ST5, the data on the condition obtained in ST4 is transmitted as a signal from the receiving side Rx to the transmitting side Tx. The transmitting side Tx demodulates the signal in step ST6, changes the communication data rate based on the data, and transmits the data. Then, in step ST7, the presence or absence of data is determined,
If YES, the process ends, but if NO, step ST
Return to 6.

In the flowchart of FIG.
The data rate may be selected from two or more values based on the value of D / PU. Alternatively, for example, whether or not a CRC code is added, that is, only whether or not an error countermeasure is performed may be executed using a certain value as a boundary. The data rate may be determined on the Tx side (only the PD / PU is determined on the Rx side, and the determination is made after sending the raw data back to the Tx side).

[0021]

As described above, according to the present invention, the communication environment is measured, and according to the environment condition at that time, errors are minimized when the environment condition is poor, and errors are minimized when the environment condition is good. Since the signal transmission rate is not reduced, the effective transmission rate is not reduced, and errors can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the embodiment.

FIG. 3 is an operation explanatory diagram of the present invention.

[Explanation of symbols]

 R receiving unit T transmitting unit DET D / U measuring unit DET1 received power measuring unit DET2 peak detecting unit 6 convolver 8 PNG 10 data demodulator 13 communication environment system 28 comparator

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04J 13/00 H04L 1/00

Claims (1)

(57) [Claims] 1. A telecommunications system for measuring a communication environment.
A transmitter having a function of transmitting test data, a power level of a received signal based on the test data,
The correlation peak obtained by the correlation operation between the received signal and the spreading code
Data on the communication environment by comparing the
A communication environmental data measuring means for determining, when sending data relating to the communication environment to the transmitter co
Means for determining a data rate based on the data
And a receiver having the following: wherein the communication environment data measuring means squares a received signal based on the test data to generate a DC signal.
And a non-DC signal from the DC signal.
And a low-pass filter for cutting the signal
Sampled DC signal from A / D converter and A / D converted and received
And a quantization circuit for determining the power of the signal.
Constant circuit, a detector for detecting the correlation peak signal, and the detected signal
Detector that detects the peak of the correlation peak signal from the
A / D conversion of the peak detection signal and a correlation peak signal
A peak detector for determining the level of the ratio between the level of power and the correlation peak signal in the received signal
A data communication device, comprising: