JPH0646033A - Spread spectrum communication equipment - Google Patents

Abstract

(57) [Summary] [Object] To provide a spread spectrum communication device capable of effectively utilizing a frequency when the bit error rate is small by changing the error correction capability according to the bit error rate. [Configuration] In the spread spectrum communication device of FIG.
A bit error rate measurement unit is provided, the bit error rate is measured, and when the bit error rate is small, the error correction capability of the error correction code unit is reduced to reduce the information transmission rate, that is, the frequency bandwidth is reduced, Effective use of frequencies becomes possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum communication device capable of effectively using frequencies.

[0002]

2. Description of the Related Art In recent years, spread spectrum communication devices are used not only for military communication but also for public communication and personal communication because they use a communication system having excellent multiple access, confidentiality and interference resistance. It became so.

A conventional spread spectrum communication device will be described below with reference to the drawings. FIG. 2 is a block diagram showing the configuration of a conventional spread spectrum communication device. In FIG. 2, 1 is a transmission unit, 2 is a reception unit, 3 is an error correction coding unit that performs error correction coding on an information signal, 4 is an information modulation unit that performs information modulation on the signal after error correction coding, and 5 is An SS modulator that spread-spectrum-modulates the information-modulated signal, a transmission frequency converter 6 that frequency-converts the spread-spectrum signal into a radio frequency band, a duplexer that divides the transmitted and received signals, and a radio frequency band signal An antenna for transmission / reception, a reception frequency conversion unit 9 for converting a signal in a radio frequency band into an intermediate frequency, an SS demodulation unit 10 for spread spectrum demodulation of the signal after frequency conversion, and 11 for information demodulation of the signal after spread spectrum demodulation. The information demodulation unit 12 is an error correction decoding unit that decodes the information-demodulated signal into the original information signal.

The operation of the conventional spread spectrum communication device configured as described above will be described below. First, in the transmission unit 1, the error correction coding unit 3 performs error correction coding on the information signal, and the information modulation unit 4 performs information modulation such as phase shift keying. Next, the SS modulator 5 performs spread spectrum modulation, the transmission frequency converter 6 performs frequency conversion into a radio frequency band, and the antenna 8 transmits the radio signal through the duplexer 7. When receiving, a radio signal is received by the antenna 8 and input to the receiving unit 2 through the duplexer 7. In the reception unit 2, the reception frequency conversion unit 9 converts the signal in the radio frequency band into an intermediate frequency, and the SS demodulation unit 10 performs spread spectrum demodulation. Next, the information demodulation unit 11 performs information demodulation such as phase shift keying, and the error correction decoding unit 12 decodes the original information signal.

By the above operation, the spread spectrum communication method can be used.

[0006]

However, in the above-described conventional spread spectrum communication apparatus, since fixed error correction coding is performed, error correction is performed more than necessary in a propagation path situation where the error rate is small. As a result, the transmission rate is increased, and a wide frequency band is required, which is a problem.

It is an object of the present invention to solve the above problems and to provide a spread spectrum communication device capable of narrowing the frequency band in a propagation path situation where the error rate is small.

[0008]

In order to achieve the above object, the present invention is provided with a bit error rate measuring unit for measuring a bit error rate, and the ability of error correction coding is changed according to the bit error rate, and the radio frequency It changes the bandwidth.

[0009]

The present invention is capable of narrowing the frequency bandwidth in spread spectrum communication according to the state of the propagation path.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the spread spectrum communication apparatus of this embodiment. In FIG. 1, 13 is a transmitting unit, 14 is a receiving unit, 15 is an error correction coding unit that performs error correction coding on an information signal, 4 is an information modulation unit that performs information modulation on the signal after error correction coding, 5 is an SS modulator that spread-spectrum-modulates the information-modulated signal, 6 is a transmission frequency converter that converts the spread-spectrum signal to a radio frequency band, 7 is a duplexer that divides the transmitted and received signals, and 8 is a radio frequency band. An antenna that sends and receives signals,
Reference numeral 9 is a reception frequency conversion unit that converts a signal in a radio frequency band into an intermediate frequency, 10 is an SS demodulation unit that performs spread spectrum demodulation of the frequency-converted signal, 11 is an information demodulation unit that performs information demodulation of the spread spectrum demodulated signal, 16 is an error correction decoding unit that decodes the information-demodulated signal into the original information signal, 1
An error rate measuring unit 7 measures a bit error rate.

The operation of the spread spectrum communication device configured as described above will be described below. First, in the transmission unit 13, the error correction coding unit 15 performs error correction coding on the information signal, and the information modulation unit 4 performs information modulation such as phase shift keying. Next, the SS modulator 5 performs spread spectrum modulation, the transmission frequency converter 6 converts the frequency to a radio frequency band, and the antenna 8 transmits the radio signal through the duplexer 7. Further, at the time of reception, the antenna 8 receives a radio signal and inputs it to the receiving unit 14 through the duplexer 7. Receiver 2
In the reception frequency converter 9, the signal in the radio frequency band is converted into an intermediate frequency, and the SS demodulator 10 performs spread spectrum demodulation. Next, the information demodulation section 11 performs information demodulation such as phase shift keying, and the error correction decoding section 16 decodes it to the original information signal.

The error rate measuring section 17 measures the bit error rate. When the bit error rate is small, it is judged that the condition of the propagation path is good, and the error correction capability of the error correction coding section 15 is lowered to perform error correction coding. To do. Then, the information transmission rate after the error correction coding becomes smaller than that of the conventional example, and the occupied frequency bandwidth of the radio signal transmitted from the antenna 8 through the duplexer 7 after the information modulation, the spread spectrum modulation and the frequency conversion is conventionally performed. Narrower than the example. The receiving section 14 frequency-converts, spread spectrum demodulates, and information demodulates the input received signal, and then the error correction decoding section 16 decodes the original information signal with the error correction capability lowered by the error rate measuring section 17. Here, the error correction capability of the error correction decoding unit 16 depends on the error rate measuring unit 17
It has been reduced to the same error correction capability as.

Since the occupied frequency bandwidth of the radio signal is narrowed, many signals can be transmitted with the same bandwidth,
Effective use of frequencies can be achieved. For example, when the bit error rate is small, the error correction capability of the error correction coding is lowered, and when the information transmission rate after the error correction coding becomes 1/2 of the conventional example, the occupied frequency bandwidth also becomes 1/2, This means that twice the signal can be transmitted with the same bandwidth.

By the above operation, it becomes possible to provide a spread spectrum communication apparatus which can effectively use the frequency when the bit error rate is small, that is, when the condition of the propagation path is good.

[0015]

As described above, according to the present invention, the bit error rate is measured, and when the bit error rate is small, the error correction capability of the error correction coding is reduced to narrow the occupied frequency bandwidth and reduce the frequency. Provided is a spread spectrum communication device that can be effectively used.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a spread spectrum communication device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional spread spectrum communication device.

[Explanation of symbols]

 1 Transmitter 2 Receiver 3 Error Correction Coder 4 Information Modulator 5 SS Modulator 6 Transmission Frequency Converter 7 Duplexer 8 Antenna 9 Reception Frequency Converter 10 SS Demodulator 11 Information Demodulator 12 Error Correction Decoder 13 Transmitter 14 reception unit 15 error correction coding unit 16 error correction decoding unit 17 error rate measurement unit

Claims (1)

[Claims] 1. A transmission section for transmitting a radio signal using a spread spectrum communication method, a reception section for receiving a radio signal according to a spread spectrum communication method, and a transmission section in the transmission section for performing error correction coding on an information signal. An error correction code section, an information modulation section that performs information modulation on the output signal of the error correction code section, an SS modulation section that performs spread spectrum modulation on the output signal of the information modulation section, and an output signal of the SS modulation section by radio. A transmission frequency conversion unit for performing frequency conversion into a frequency band, a reception frequency conversion unit in the reception unit for performing frequency conversion of a radio frequency band signal into an intermediate frequency, and an SS for performing spread spectrum demodulation of the output signal of the reception frequency conversion unit A demodulation unit, an information demodulation unit that demodulates the output signal of the SS demodulation unit, and an error correction decoding unit that decodes the output signal of the information demodulation unit into the original information signal. And a error rate measuring unit for measuring a bit error rate, the spread spectrum communication apparatus, characterized in that it is effective utilization of frequency when by changing the error correction capability, the bit error rate is smaller by a bit error rate.