JP2000224247A - Digital wireless communication system - Google Patents

Abstract

(57) [Problem] To provide a data communication according to a communication state by changing a frame configuration in a digital wireless communication system that performs quasi-synchronous detection using pilot symbols. SOLUTION: Based on communication status information input to a signal generation unit 1, a frame configuration in which a pilot symbol insertion interval is shortened when fluctuations in a transmission path become severe or when it is desired to reduce transmission data reproduction errors. In order to reduce data reproduction errors and to make transmission line fluctuations gentler or to increase the data transmission rate, a frame structure with a longer pilot symbol insertion interval is used to transmit data. Efficiency can be improved, and data communication according to the communication state can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital radio communication system for performing quasi-synchronous detection using pilot symbols.

[0002]

2. Description of the Related Art In a digital radio communication system, a technique disclosed in Japanese Patent Application Laid-Open No. 1-196924 has been known as a method relating to pilot symbols when performing quasi-synchronous detection. This has a frame configuration as shown in FIG. 3, in which one known pilot symbol is inserted for every N data symbols in the transmission section. Using the pilot symbols, the receiver estimates the transmission line distortion of the frequency offset amount and the amplitude distortion amount. Then, the data symbol is decoded based on the estimation information, and the data is reproduced.

[0003]

SUMMARY OF THE INVENTION In wireless communication,
Although the transmission path varies due to fading, the variation of the transmission path is not uniform especially in land mobile communication. In the wireless communication as described above, if the fluctuation of the transmission path becomes very severe, it is necessary to shorten the interval between insertions of pilot symbols in order to prevent a data reproduction error. When it becomes moderate, it is desired to increase the data symbol efficiency in one frame by increasing the insertion interval of pilot symbols.

In the conventional method, since the insertion interval of the pilot symbols is fixed to one for every N data symbols, if the insertion interval of the pilot symbols is determined from the viewpoint of reducing data reproduction errors, When the fluctuation of the transmission path becomes gentle, redundant pilot symbols are inserted, which is not desirable from the viewpoint of data transmission efficiency.

[0005] In wireless communication, it is sometimes necessary to change the transmission speed depending on the quality required for transmission data. For example, when it is desired to reduce transmission data reproduction errors, it is necessary to shorten the interval between insertions of pilot symbols, but in that case, the data transmission rate is reduced. On the other hand, if it is desired to increase the data transmission rate even if data reproduction errors are allowed to some extent, it is necessary to increase the interval between insertions of pilot symbols. However, in the conventional method, since the insertion interval of pilot symbols is fixed, the quality of transmission data and the transmission rate cannot be changed.

According to the present invention, the reproduction error can be reduced or the transmission efficiency can be improved as required by changing the insertion interval of pilot symbols in accordance with communication conditions such as fluctuations in the transmission path and data quality. Or to be able to do so.

[0007]

According to the present invention, there is provided a digital radio communication system in which quasi-synchronous detection is performed using pilot symbols. It changes according to the state or data quality. That is, in other words, the number of data symbols in one frame is changed in accordance with the communication conditions and the like.

As a result, when the fluctuation of the transmission path becomes severe or when it is desired to reduce the reproduction error of the transmission data,
By reducing the pilot symbol insertion interval to reduce data reproduction errors, and when the transmission path fluctuations become milder or when it is desired to increase the data transmission speed, the pilot symbol insertion interval can be increased. One system can increase the data transmission efficiency.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a digital radio communication system in which quasi-synchronous detection is performed using a known pilot symbol, the insertion interval of the pilot symbol is changed according to the communication situation. This is a digital radio communication system characterized by reducing the data reproduction error by shortening the pilot symbol insertion interval, and increasing the data transmission efficiency by increasing the pilot symbol insertion interval. It has the effect of doing.

According to a second aspect of the present invention, there is provided a digital radio communication system in which quasi-synchronous detection is performed using a PSK symbol as a pilot symbol, wherein the insertion interval of the pilot symbol is changed in accordance with communication conditions. This is a communication method that has an effect of reducing data reproduction errors by shortening the pilot symbol insertion interval and increasing data transmission efficiency by increasing the pilot symbol insertion interval.
In addition, since the PSK symbol serves not only as a pilot symbol but also as a data symbol, the PSK symbol has an effect of suppressing a decrease in data transmission amount as compared with a case where a known pilot symbol is used.

According to a third aspect of the present invention, in the digital radio communication system for performing quasi-synchronous detection using a known pilot symbol, the insertion interval of the pilot symbol is changed according to the state of a transmission line. This is a digital wireless communication system that reduces the data reproduction error by shortening the pilot symbol insertion interval when the transmission line fluctuates greatly, and reduces the pilot error when the transmission line fluctuates moderately. It has the effect of increasing the data transmission efficiency by lengthening the symbol insertion interval.

According to a fourth aspect of the present invention, in a digital radio communication system in which quasi-synchronous detection is performed using a PSK symbol as a pilot symbol, an insertion interval of the pilot symbol is changed in accordance with a state of a transmission line. A digital wireless communication system that reduces data reproduction errors by shortening the pilot symbol insertion interval when transmission line fluctuations become severe, and pilot symbols when transmission line fluctuations become mild. Has the effect of increasing the data transmission efficiency by lengthening the insertion interval. In addition, since the PSK symbol serves not only as a pilot symbol but also as a data symbol, the PSK symbol has an effect of suppressing a decrease in data transmission amount as compared with a case where a known pilot symbol is used.

According to a fifth aspect of the present invention, in a digital radio communication system in which quasi-synchronous detection is performed using a known pilot symbol, the insertion interval of the pilot symbol is changed in accordance with data quality. This is a digital radio communication system.When transmitting important data, the pilot symbol insertion interval is shortened to reduce data reproduction errors, and when it is desired to increase the data transmission speed, the pilot symbol insertion interval is increased. Longer length has the effect of increasing data transmission efficiency.

According to a sixth aspect of the present invention, in a digital radio communication system in which quasi-synchronous detection is performed using a PSK symbol as a pilot symbol, the insertion interval of the pilot symbol is changed in accordance with data quality. This is a wireless communication system.When transmitting important data, shorten the pilot symbol insertion interval to reduce data reproduction errors, and if you want to increase the data transmission speed, increase the pilot symbol insertion interval. This has the effect of increasing the data transmission efficiency. Also, the PSK symbol has a role not only as a pilot symbol but also as a data symbol,
This has an effect of suppressing a decrease in the amount of data transmission as compared with the case where a known pilot symbol is used.

[0015] The invention according to claim 7 is the invention according to claims 1 to 6.
In the digital wireless communication system according to any of the above,
This is a digital wireless communication system characterized in that a data symbol modulation method is a multi-level QAM method, and has the same effect. In addition, since the data symbol modulation method is a multi-level QAM method, data transmission efficiency is improved. Has the effect of improving.

The invention according to claim 8 is the invention according to claims 1 to 7
A communication system using the digital wireless communication system according to any one of claims 1 to 7, wherein a highly reliable communication system utilizing the operation and effect of the digital wireless communication system according to any one of claims 1 to 7 can be constructed. Has an action.

According to a ninth aspect of the present invention, there is provided a signal generating section for generating a quadrature baseband signal and a frame signal in which a pilot signal is inserted, a transmitting radio section for quadrature modulating and amplifying the frame signal, and transmitting a signal. Transmitting antenna,
And a receiving antenna for receiving a transmitted signal, a receiving radio unit for amplifying and quadrature demodulating the received signal, and a transmission for estimating a signal distortion amount in a transmission path using the quadrature demodulated signal. A path distortion estimating unit, a receiving device having a quasi-synchronous detection unit that performs transmission line distortion compensation using the quadrature demodulated signal and the distortion amount and outputs reproduced data, wherein the signal generation unit includes: An orthogonal baseband signal generator for generating a band signal; and a first base station for inserting a pilot signal to form a first frame configuration.
A pilot signal insertion unit, a second pilot signal insertion unit that inserts a pilot signal to form a second frame configuration, and a changeover switch that switches a frame configuration based on a communication status signal. This is a digital wireless communication system that can use a signal having an appropriate frame configuration according to a communication situation, and thus has an effect that a highly reliable communication system can be constructed.

An embodiment of the present invention will be described below with reference to FIGS.

(Embodiment) FIG. 1 is a block diagram of a communication system using a digital radio communication system according to an embodiment of the present invention. 1A illustrates a communication device on the transmission side, FIG. 1B illustrates a configuration example of a signal generation unit included in the communication device on the reception side, and FIG. 1C illustrates a configuration example of a signal generation unit included in the communication device on the transmission side.

In FIG. 1A, reference numeral 1 denotes a signal generation unit having an orthogonal baseband signal generation unit and a pilot signal insertion unit, which maps input data on a complex plane corresponding to a predetermined modulation method. Then, a data symbol is generated, and pilot symbols are inserted into the data symbol sequence at appropriate intervals based on the input communication status information. The signal of the frame configuration generated in this way is output to the transmission radio unit 2.

As the communication status information to be input, it is possible to use transmission channel information including the fluctuation status of the transmission channel, and to use data quality information including the quality and transmission speed of transmission data.

Known symbols and PSK symbols can be used as pilot symbols. When a PSK symbol is used as a pilot symbol, input data is also assigned to the PSK symbol. Further, as a modulation scheme of the data symbol, a multi-level QAM scheme can be used.

The transmission radio section 2 performs quadrature modulation, power amplification and the like, and transmits a signal from the antenna 3.

On the receiving side shown in FIG.
, And the reception radio section 5 performs amplification, quadrature demodulation, and the like. The transmission path distortion estimating unit 6 includes a receiving radio unit 5
, A pilot symbol is detected from the output signal, and a channel distortion amount such as a frequency offset amount and an amplitude distortion amount is estimated. Then, in the quasi-synchronous detection unit 7, the reception radio unit 5
On the basis of the output signal and the estimation information output from the transmission path distortion estimating section 6, and outputs decoded reproduction data.

The interval between the pilot symbols inserted on the transmitting side is determined based on the communication status information input to the orthogonal baseband signal generator and the pilot signal inserter of signal generator 1.

FIG. 2 shows that the insertion interval of pilot symbols is 2
It is an example of a frame configuration when changing to stages. Frame 8 has a data symbol length of N symbols and frame 9
Has a data symbol length of M symbols, and sets N <M.

For example, FIG. 1C shows the configuration of the signal generator 1 in the case where the insertion interval of pilot symbols is changed in two steps as a frame configuration as shown in FIG. Reference numeral 10 denotes an orthogonal baseband signal generation unit that generates an orthogonal baseband signal, 11 denotes a first pilot signal insertion unit that inserts a pilot signal so as to form a first frame configuration, 1
2 is a second pilot signal insertion unit that inserts a pilot signal so as to form a second frame configuration, 13 is a switching control unit that controls switching of frame configurations using communication status information, and 14 is a switching control unit 13 Is a changeover switch for switching the frame configuration based on the above control.

When the transmission path information is used as the communication status information, when it is detected that the fluctuation of the transmission path has become severe, the frame configuration is set as in frame 8, and it is detected that the fluctuation of the transmission path has become gentle. In such a case, the frame configuration is set as in frame 9.

When the data quality information is used as the communication status information, and when it is detected that the reproduction error of the transmission data is to be reduced, the frame configuration is set as in frame 8,
If it is detected that the data transmission speed is to be increased, the frame configuration is set as in frame 9.

As a result, the pilot symbol insertion interval changes in two stages.

By changing the pilot symbol insertion interval by such a communication method, it is possible to reduce a data reproduction error or increase a transmission speed, and perform data communication corresponding to a change in a transmission path. be able to. By using such a communication method, a highly reliable communication system can be constructed.

In the above example, the pilot symbol insertion interval is changed in two stages, but a configuration in which the number of stages can be changed depending on the communication status information may be increased.

[0033]

As described above, according to the present invention, when the insertion interval of pilot symbols is changed in accordance with the communication situation, when the transmission line fluctuates greatly or when it is desired to reduce transmission data reproduction errors. To reduce data reproduction errors by shortening the pilot symbol insertion interval, increase the pilot symbol insertion interval when transmission path fluctuations become mild or when the data transmission rate is desired to be increased. Thus, the data transmission efficiency can be improved, data communication can be performed according to the communication conditions, and the use of such a communication method has an effect that a highly reliable system can be constructed.

[Brief description of the drawings]

FIG. 1 is a block diagram of a digital wireless communication system according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a frame configuration according to an embodiment of the present invention;

FIG. 3 is a frame configuration diagram of a conventional example.

[Description of Signs] 1 signal generation unit 2 transmission radio unit 3 transmission antenna 4 reception antenna 5 reception radio unit 6 transmission line distortion estimation unit 7 quasi-synchronous detection unit 8 frame when data symbol number is N symbol 9 data symbol number Where M is an M symbol 10 Orthogonal baseband signal generation unit 11 First pilot signal insertion unit 12 Second pilot signal insertion unit 13 Switching control unit 14 Switching switch

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Masayuki Orihashi 3-10-1, Higashi-Mita, Tama-ku, Kawasaki, Kanagawa Prefecture Inside Matsushita Giken Co., Ltd. (72) Akihiko Matsuoka 3-chome, Higashi-Mita, Tama-ku, Kawasaki-shi, Kanagawa No. 10 No. 1 Matsushita Giken Co., Ltd. F term (reference) 5K004 AA05 AA08 FB01 FD05 JB01 JD05 5K067 AA23 BB02 DD13 DD25 DD27 DD51 EE02 EE10 GG11

Claims (9)

[Claims] 1. A digital radio communication system in which quasi-synchronous detection is performed using known pilot symbols, wherein the insertion interval of the pilot symbols is changed in accordance with communication conditions. 2. Phase shift keying (PSK)
g) A digital radio communication system in which quasi-synchronous detection is performed using a symbol as a pilot symbol, wherein the insertion interval of the pilot symbol is changed in accordance with a communication situation. 3. A digital radio communication system in which quasi-synchronous detection is performed using a known pilot symbol, wherein the insertion interval of the pilot symbol is changed in accordance with the state of a transmission line. 4. A digital radio communication system in which quasi-synchronous detection is performed using a PSK symbol as a pilot symbol, wherein the insertion interval of the pilot symbol is changed in accordance with the state of a transmission line. 5. A digital radio communication system in which quasi-synchronous detection is performed using known pilot symbols, wherein the insertion interval of the pilot symbols is changed in accordance with data quality. 6. A digital radio communication system for performing quasi-synchronous detection using a PSK symbol as a pilot symbol, wherein the insertion interval of the pilot symbol is changed in accordance with data quality. 7. The digital wireless communication system according to claim 1, wherein a modulation scheme of a data symbol is multi-level quadrature modulation (QAM: Quadrature Amplitude Modulation).
digital radio communication system, which is characterized in that the digital radio communication system is used. 8. A communication system using the digital wireless communication system according to claim 1. 9. A signal generation unit for generating a quadrature baseband signal and a frame signal into which a pilot signal is inserted,
A transmission radio unit that amplifies the frame signal by performing quadrature modulation,
A transmitting apparatus having a transmitting antenna for transmitting a signal, a receiving antenna for receiving a transmitted signal, a receiving radio unit for amplifying and quadrature demodulating the received signal, and a signal on a transmission path using the quadrature demodulated signal And a quasi-synchronous detector for performing transmission path distortion compensation using the quadrature demodulated signal and the distortion amount and outputting reproduced data. The generation unit includes an orthogonal baseband signal generation unit that generates the orthogonal baseband signal, a first pilot signal insertion unit that inserts a pilot signal so as to form a first frame configuration, and a second frame configuration. A second pilot signal insertion unit for inserting a pilot signal so as to form a frame, and a changeover switch for switching a frame configuration based on a communication status signal. Digital radio communication system according to claim.