JPH04196944A - Multilevel modulating/demodulating communication system - Google Patents

Abstract

PURPOSE:To establish synchronization by a simple circuit on the reception side by using any special signal point concerning the specified phase plane of plural phase planes for transmitting information, detecting this specified signal point on the reception side and establishing synchronization for the combination of phase planes. CONSTITUTION:On a first phase plane (a), 24 signal points are arranged and on a second phase plane (b), 23 signal points are arranged. On a transmission side 10, a ROM 12 outputs bit trains D11 and D12. so that the bit patterns of inputted nine information bits can be corresponding to the combination of each one signal point on the first and second phase planes. A parallel/serial conversion circuit 13 executes parallel/serial conversion from the bit trains D11 and D12 to 6 bit trains, inputs them to a modulator 14 and generates a modulated signal M. On a reception side 20, a demodulator 21 demodulates the received modulated signal and outputs it to a coincidence judgement circuit 22 and a serial/parallel conversion circuit 23. The coincidence judgement circuit 22 outputs a synchronizing pulse F synchronously with a time slot judged as being on the first phase plane and not being on the second phase plane, namely, as containing the 24th signal point among the bit patterns of the inputted bit trains.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a multilevel modulation/demodulation communication system.

[Conventional technology]

A multilevel modulation/demodulation communication system is used for wireless communication, in which a plurality of signal points are arranged on the phase plane of a modulated signal, and each signal point is transmitted in correspondence with one information symbol. for example,
16-value and 64-value, which arrange 16, 64, and 256 signal points in a square shape.

The 256-value orthogonal amplitude modulation and demodulation communication system uses 4 bits.

8-bit or 16-bit information symbols can be transmitted in one time slot. The number of signal points is large (I see, the amount of information that can be transmitted in one time slot is large, and radio waves can be used effectively.In return, the larger the number of signal points, the more the transmission hardware and transmission path will need to be The requirements for characteristics will also become stricter.

[Problem to be solved by the invention]

Now, if one information symbol is transmitted by a combination of signal points on a plurality of phase planes, the degree of freedom in setting the number of signal points increases. Therefore, it is convenient to optimize the number of signal points in order to achieve both effective use of radio waves and strict requirements for transmission hardware, etc. However, in order to do this, it is necessary to detect the separation of signal point combinations on the receiving side, or in other words, to establish synchronization of signal point combinations.

The purpose of the present invention is to combine signal points on multiple phase planes into one
An object of the present invention is to provide a multilevel modulation/demodulation communication system that can transmit two information symbols and easily establish synchronization of a combination of signal points on the receiving side.

[Means to solve the problem]

The multilevel modulation/demodulation communication system of the present invention arranges a plurality of predetermined signals/points on the phase plane of a modulated signal, and uses combinations of the signal points selected one by one from the plurality of temporally different phase planes as information symbols. In a multi-level modulation/demodulation communication system that corresponds to each of the above information symbols, on the transmitting side, only the phase planes in a predetermined order among the plurality of phase planes used for the combination of the signal points to correspond to the information symbols are Using the signal point that is not used in the phase plane,
On the receiving side, synchronization of the combination of signal points is established by detecting the phase planes in the predetermined order. [Example] Next, the present invention will be described with reference to the drawings.

FIGS. 1(a) and 1(b) are block diagrams illustrating a transmitting side 10 and a receiving side 20 of a communication system using one embodiment of the present invention.

The information symbol transmitted in this embodiment is a symbol that can be represented by 9 bits, and has 2'=512 states. These 512 states correspond to combinations of signal points of the first and second two phase planes.

As shown in FIG. 2(a), 24 signal points are arranged on the first phase plane. Also, in the second phase plane, as shown in Fig. 2(b)
As shown in the figure, 23 signal points are arranged. By ordering both phase planes so that the signal points of the first phase plane are transmitted first and then the signal points of the second phase plane, there are 24×23=552 combinations of signal points of both phase planes. Become. Of these 552 combinations, 512 are made to correspond to each state of the information symbol and engineering to engineering.

Now, the time series of information symbols to be transmitted is input to the transmitting side 10 as a nine-column bit string Dto.

The ROM 12 is configured to make the bit pattern of 9 information bits input as the bit string 10 correspond to a combination of one signal point each on the first phase plane and the second phase plane shown in FIGS. 2(a) and (b). Output the bit string □, D□2. First phase plane.

Since each signal point on the second phase plane is part of the signal points of the 64 (=2') value orthogonal amplitude modulation communication system, each of the six bit strings D□□+I)t. Let us represent each signal point by. However, the number of signal points actually used is 24.
or 23, and the bit string is 8. Each D1□ contains only an amount of information equivalent to about 4.5 columns.

The parallel-serial conversion circuit 13 outputs the bit string Dll in the first half of one time slot of the bit string D1□lDI□, and outputs the bit string D12 in the second half of the bit string D1.
Parallel-serial conversion of D1□ into 6 bit strings. The bit string from the parallel-to-serial conversion circuit 13 is input to a well-known modulator 14 for 64-value orthogonal amplitude modulation to generate a modulation signal M.

Modulated signal M is transmitted to receiving side 20 via a transmission path. A well-known demodulator 21 for a 64-value orthogonal amplitude modulation signal demodulates the received modulation signal M, and converts the 6 bit strings, which are demodulated output signals, to a coincidence determination circuit 22 and a serial-parallel conversion circuit 23.
Output to.

The coincidence determination circuit 22 detects a signal that matches the 24th signal point in the bit pattern of two consecutive time slots of the input bit string, that is, a signal point that is in the first phase plane but not in the second phase plane. It is determined whether the point is likely to occur, and a synchronization pulse F is output in synchronization with the time slot determined to include the 24th signal point.

The serial-parallel conversion circuit 23 converts the input six bit strings into
The bit strings D2□l D2 are distributed alternately to each time slot, and serial-parallel conversion is performed so as to distribute them to the bit string D21 at the timing of the synchronization pulse F.
Outputs ゜. By performing serial-to-parallel conversion using the synchronizing pulse F as a phase reference in this way, the bit string D2□l
D2° is the bit string D11°Dl on the transmitting side 10, if transmission errors are ignored. matches.

The ROM 24 converts the nine bit strings input by the ROM 12 on the transmitting side 10 into a bit string DIIIDI. The bit string D211D2.degree. is converted into a nine-column bit string by the inverse conversion to the bit string D211D2.degree., and if transmission errors are ignored, a bit string D20 that matches the bit string D10 on the transmitting side 10 is output.

As can be seen from the action of the synchronization pulse F in the serial-parallel conversion circuit 23, synchronization of the combination of signal points is established in the coincidence determination circuit 22.

In the embodiment described above, one information symbol is transmitted in two phase planes, and the difference in the number of signal points used for each is set to 1, but one information symbol is transmitted in three or more phase planes. The difference in the number of signal points transmitted and used for each is 2
Alternatively, the present invention can be applied to obtain the same effect even when the number is greater than that.

〔Effect of the invention〕

As explained above, the present invention uses a specific signal point for a specific phase plane among a plurality of phase planes for transmitting information, and by detecting this specific signal point on the receiving side, the phase plane It establishes the synchronization of the combination of
Synchronization can be established on the receiving side with a simple circuit.

[Brief explanation of the drawing]

FIGS. 1(a) and (b) are block diagrams showing a transmitting side 10 and a receiving side 20 of a communication system using an embodiment of the present invention, and FIGS. It is a figure which shows the signal point arrangement|positioning in a 1st phase plane and a 2nd phase plane. 10...Sending side, 12.24...ROM, 13...
- Parallel-serial conversion circuit, 14... Modulator, 20... Receiving side, 21... Demodulator, 22... Coincidence determination circuit, 2
3...Series-parallel conversion circuit.

Claims (1)

[Claims] In a multilevel modulation/demodulation communication system in which a plurality of predetermined signal points are arranged on a phase plane of a modulated signal, and a combination of the signal points selected one by one from a plurality of temporally different phase planes corresponds to each information symbol. , on the transmitting side, the signal points that are not used in the other phase planes are used for only the phase planes in a predetermined order among the plurality of phase planes used for the combination of the signal points to correspond to the information symbols, A multilevel modulation/demodulation communication system, characterized in that, on the receiving side, synchronization of the combination of signal points is established by detecting the phase planes in the predetermined order.