JPH01122242A - Radio digital transmission/reception system - Google Patents

Abstract

PURPOSE:To simplify the whole of a transmission/reception system by devising the processing of an input data string to use a MODEM of M-level QAM as it is at the time of switching between M-level QAM and four-phase PSK modulation. CONSTITUTION:When the quality of a line is deteriorated by the degradation of the radio propagation state, controllers 7 and 14 in transmission and reception sides are operated. A switching device 3 of 16-level QAM(quadrature amplitude modulation)-four phase PSK in a transmission side T ignores the input of two strings corresponding to a second data string d2 and performs coding only with quadrature discrimination bits B1-B4 as the input of two strings corresponding to a first data string d1. Since the data of a third data string d3 consists of only information of quadrature discrimination bits B1-B4 in the reception side R, error in output data of the third data string d3 is reduced even if the line state is bad. Thus, the whole of the transmission/reception system is simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wireless transmission system for digital signals, and more particularly to a transmitting and receiving system for wireless digital transmission. To further specify the present invention, the M value Q A M (
quadrature amplitude modul
ation) method and 4-phase PSK (phase s
The present invention relates to a switching function between the high-key modulation method and the high-key modulation method.

[Conventional technology]

Conventionally, it seems that there is no switching transmission function between M-value QAM and 4-phase PSK modulation, but if we infer from a numerical switcher, it is possible to switch between M-value QAM and 4-phase PSK modulation modulators. A system is conceivable in which separate devices are provided and they are switched at the sending end and the receiving end.

[Problem that the invention seeks to solve]

The transmission/reception system described above uses the M-value QAM method and the 4-value QAM method.
Since the phase PS must have an independent modulator/demodulator for each modulation method, there are disadvantages in that the entire system becomes complicated and the cost increases.

[Means for solving problems]

The wireless digital transmission/reception system of the present invention is a system for transmitting and receiving a data string of a digital signal via a wireless line, and an M value Q for modulating a plurality of said data strings.
AM means and transmitting means and receiving means capable of switching between the four-phase PSK modulating means that modulates only one of the plurality of data streams; and a control device for switching the MglQAM means to the four-phase PSK modulating means. It is characterized by having the following.

(Function) Therefore, according to the present invention, only one of a plurality of data streams can be transmitted and received using 4-phase PSK modulation. This makes it possible to simplify the overall system configuration.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic block diagram showing an embodiment according to the invention, in which the transmitting side T includes a first unit 1 for data processing into which a first data sequence d1 of a digital signal is input; 1, a second unit 6 for data processing that inputs the second data string d2 of the digital signal, and a switching device connected to the unit 6 and the differential converter 2. 3, a 16-level QAM (orthogonal modulation) modulator 4 connected to the switching device 3, and a transmitter 5 connected to the modulator 4.

Note that the switching device 3 selects 16-value QAM or 4-value QAM.
The control device 7 switches whether phase PSK modulation is selected.

The receiving side R includes a receiver 8 that receives the wireless signal sg from the transmitter 5, a 16-QAM demodulator 9 connected to the receiver 8, and a switching device 10 connected to the demodulator 9. , a differential converter 11 connected to the switching device lO, a third unit 12 for data processing connected to the differential converter 11 and outputting the third data string d3, and the above switching connected to the device 10, the fourth data string d4
A fourth unit 1 for data processing that outputs
It consists of 3.

Note that the switching device 10 selects and switches between 16-level QAM and 4-phase PSK modulation using the control device 14.

Here, to explain the operation of the embodiment shown in FIG.
The data string d1 is converted into two columns in the first unit 1, subjected to differential conversion of OR in the differential converter 2, and then used as bits 81 to B4 for quadrant determination, which will be described later.

The second data string d2 is converted into two columns in the second unit 6, and enters the 16-QAM modulator 4 through the switching device 3 together with the quadrant determination bits 81 to B4.
The signal is modulated and transmitted by the transmitter 5.

On the receiving side R, the two rows of quadrant determination bits 81 to B4 demodulated by the 16-QAM demodulator 9 via the receiver 8 are
The differential converter 11 performs differential conversion of the logical difference via the switching device IO, and outputs the data as a third data string d3 via the third unit 12. Note that the remaining two columns are sent out as the fourth data column d4 in almost the same way.

Here, when the quality of the line deteriorates due to deterioration of the wireless propagation state, the control device 7.14 on the transmitting and receiving side operates, and the 16-QAM-4-phase PSK switching device 3 on the transmitting side T
Ignoring the input of the second column corresponding to the data column d2, the first
Coding is performed only with bits B1 to B4 for each quadrant, which are the two input columns corresponding to the data string d1.

Note that FIG. 2 shows an example of 16-value QAM mapping. For example, in this figure, when modulating to 4-phase PSK, 2 bits other than quadrant determination bits 81 to B4 are set to (1, 1).
By fixing it to , four-phase phase modulation is realized. (1
, 1) is to maximize the advantage of 4-phase PSK by making the inter-symbol distance as far as possible.

There is no problem with the increase in level caused by this, if it is adjusted by automatic transmission output adjustment of the illustrated path of the transmitter 5.

On the receiving side R, the data of the third data string d3 is composed only of the information of the quadrant determination bits 81 to B4, so even when the line condition is poor, the output data of the third data string d3 will be erroneous. becomes less. In this case, the switching device 10 on the receiving side R mainly processes the fourth data string d4. This is because the fourth data string d4 becomes a meaningless data output when switched to 4-phase PS, so some kind of treatment must be taken.

FIG. 3 is a schematic block diagram showing a second embodiment of the present invention. The embodiment of FIG. 1 is a case of 16-value QAM, whereas the embodiment of FIG. Indicate the case.

The human-powered data strings dll to d13 become three columns, and the modulator 4
In this case as well, the data string dll used for the quadrant determination bits 81 to B4 can be saved in substantially the same manner as described above, by only requiring six columns of human power. Furthermore, −numerically, M
Switching can also be performed in the same manner in M-value QAM where is an integer.

Here, to summarize the above embodiment in another way, this embodiment uses a modulator/demodulator with M value Q A M as is, and controls the input data of the modulator to
It switches between AM and 4-phase PSK modulation.

That is, in this embodiment, the M-value QA of digital wireless transmission is
This is an M-4-phase PSK modulation switching transmission system, and is characterized by a modulation switching device that modulates only one of several data streams into a 4-phase PSK modulation and transmits it.

〔Effect of the invention〕

As explained above, the present invention utilizes M-value QAM and 4-phase PS
When switching to K modulation, the M4IiQ A M modulator/demodulator can be used as is by devising the manual processing of the data string, which has the effect of simplifying the entire transmitting/receiving system and reducing the overall cost. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is an explanatory diagram of the same, and FIG. 3 is a block diagram showing another embodiment of the present invention. 1.6, 12.13-----Data processing unit, 2, 11----------Differential converter, 3, l O----- ------------Switching device, 4---------------16-level QAM modulator, 5---------------------・・・・・・
- Transmitter, 7, 14----------Control device, 8-------------Receiver, 9
-----------Axis - 16-value QAM demodulator.

Claims (1)

[Claims] 1) A system for transmitting and receiving a data string of a digital signal via a wireless line, comprising M-value QAM means for modulating a plurality of said data strings, and a data string of one of said plurality of data strings. Modulate only columns 4
A wireless digital transmission/reception system comprising: transmitting means and receiving means capable of switching phase PSK modulation means; and a control device for switching the M-value QAM means to the four-phase PSK modulation means. 2) According to claim 1, wherein the M-value QAM means and the 4-phase PSK modulation means include a switching device between M-value QAM and 4-phase PSK modulation, and an M-value QAM modulator or demodulator. The described wireless digital transmitting and receiving system.