JP2000134186A - Infrared communication method and its system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a data transmission efficiency in an infrared communication system. SOLUTION: Transmission efficiency is improved by desirably assigning and using 12 ways of chip patterns not used for a data part to a preamble part and a start flag part and a stop flag part in the IrDA standard frame format, so as to reduce number of chips in parts other than the data part in the frame format. That is, the preamble part consists of 4-chip dummy strings and compare strings not used for data respectively to reduce a redundant bit string of the preamble part. Furthermore, the start flag part and the stop flag part use respectively 4-chips which are not used for data. Thus, the preamble part that conventionally required 256 chips uses only 8 chips, and the start flag part and the stop flag part having respectively required conventionally 32 chips use only 4 chips, resulting that 304 chips can be reduced per one frame overall.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared communication system and system, and more particularly, to a method of transmitting one symbol of transmission data to a quaternary P
The present invention relates to an infrared communication system and a system for transmitting and receiving a frame format represented by a four-chip pattern of PM (Pulse Position Modulation).

[0002]

2. Description of the Related Art IrDA (Infrared Data Association)
There is a method in which print data is received by infrared communication from a personal computer or the like having an infrared communication function conforming to the IrDA standard specified by the JIS, and the print data is transferred to a printer controller without using a printer cable. FIG. 7 shows the IrDA standard of such a frame format of the infrared communication system.

[0003] A preamble (Preamble) part defined by the IrDA standard with a communication speed of 4 Mbps transmits a total of 256 chips by repeating a predetermined chip sequence (16 chips) 16 times, thereby achieving frame synchronization. It has become. The start flag portion following the preamble portion is composed of a predetermined 32 chip sequence, and the next data portion is a 4 × n chip sequence (n is a natural number of 6 <n ≦ 2006). The stop flag section is composed of a predetermined 32 chip row, like the start flag section.

[0004] In the data section, a quaternary PPM system is employed as a modulation system for infrared transmission at 4 Mbps. In the four-valued PPM, as shown in FIG. 8A, four times are generated when a 500 ns unit time (symbol time) is divided into four equal parts.
The combination of 2-bit data (“00”, “01”,
"10", "11"). That is,
In the quaternary PPM, one chip is one unit time (one symbol time) in four chips.

Therefore, in the 4-level PPM, data is represented by four types of chip patterns, and the remaining 12 possible chip patterns are not used as data as shown in FIG.

[0006]

In such a frame format of the infrared communication system, the preamble portion requires 16 chips × 16 times = 256 chips.
Regarding the start flag section and the stop flag section, 3
2 chips + 32 chips = 64 chips are required. Therefore, there is a problem that there is a redundant portion and transmission efficiency is poor.

An object of the present invention is to provide an infrared communication system and a system that improve transmission efficiency.

[0008]

According to the present invention, there is provided a frame format having a preamble section, a start flag section, a data section, and a stop flag section in this order, wherein one symbol of the data section is a 4-level PPM 4-chip. An infrared communication system represented by a pattern, wherein a 4 × 2 chip pattern other than the chip pattern of the data section is assigned to the preamble section, and the chip of the data section is assigned to the start flag section and the stop flag section. An infrared communication system characterized in that four chip patterns other than the pattern are assigned respectively.

[0009] The preamble portion is composed of a 4-chip dummy column and a 4-chip compare column following the 4-chip dummy column, and the compare column is to be compared with a comparison target column on a receiving side. It is characterized by.

Further, according to the present invention, a preamble portion,
An infrared communication system comprising a frame format having a start flag section, a data section, and a stop flag section in this order, wherein one symbol of the data section is represented by a 4-chip pattern of quaternary PPM. 4 other than the chip pattern of the data section
A transmission means for allocating a × 2 chip pattern and allocating and transmitting four chip patterns other than the chip pattern of the data part to the start flag part and the stop flag part, respectively, is obtained. .

[0011] The preamble portion is composed of a 4-chip dummy column and a 4-chip compare column following the 4-chip dummy column, and the compare column is to be compared with a comparison target column on a receiving side. It is characterized by
A comparing unit that receives a frame format signal from the transmitting unit and performs a comparison process between the 4-chip compare sequence following the dummy sequence and the comparison target sequence; and when a match is detected by the comparison process. It is characterized by including receiving means for recognizing a subsequent chip pattern as the start flag.

The operation of the present invention will be described. Preamble part,
As the start and stop flag portions, twelve types of chip patterns not used in the data portion are arbitrarily assigned and used, thereby reducing the number of chips other than the data portion of the frame format and improving transmission efficiency. More specifically, the preamble portion is configured by a 4-chip dummy column and a compare column, each of which is not used as data, to shorten the redundant bit sequence of the preamble portion. The start flag and the stop flag use four chips that are not used as data.

As a result, the preamble portion requires 256 chips, but becomes 8 chips, and the start flag and stop flag portions require 32 chips, but each becomes 4 chips. Chips can be reduced.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a diagram showing a configuration of a frame format according to the present invention. As shown in FIG. 3, the preamble portion is composed of four chips of "dummy column" and four chips of "compare column". The “dummy string” is a part necessary for the receiving side to reliably recognize the subsequent “compare string”, and the “compare string” is a part necessary for actually achieving frame synchronization. The receiving side has the same chip row as the “compare row”, which is referred to as a “comparison target row”.

FIG. 2A is a diagram showing a design example of a preamble part according to one embodiment of the present invention, where "dummy column" = 1.
111, “compare sequence” = 0110. That is,
In the example of FIG. 2, the preamble part = 11110110 = 8
Consists of chips. If this data string is sent,
On the receiving side, a “comparison target column” having the same chip pattern as the “compare column” shown in FIG. 2B is prepared in advance. (B) in FIG. 2B shows the state in which the preamble portion is stored in the data receiving buffer on the receiving side with time, and the receiving side compares the data in the receiving buffer with the “column to be compared”. , One by one.

Here, the receiving side compares the "conveyer target column" with the data in the receiving buffer after starting the reception. Because, before the start of reception, the reception buffers are all in an undefined state,
This is because the same chip row can be used. In FIG. 2B, the indeterminate data exists in the reception buffer. This is indicated by "X". At this time, even if the undefined part of “X” is “0” or “1”, “comparison target column”
Does not appear. Also,
A chip row identical to the “comparison target row” does not appear. The receiving side can recognize the same chip row as the “comparison target row” that the receiving side has only when the state is set. At this time, the receiving side recognizes that the transmission data is an infrared frame, and synchronization is achieved.

In other words, in the present invention, the design is made such that the same chip row as the "compare row" does not appear in the reception buffer until all of the "compare row" appear, so that the preamble which conventionally required 256 chips is required. The unit can be designed with 8 chips. Thus, the transmission time per frame can be reduced by {(256-8) / 4} × 500 nS = 31 μS (4 chips = 500 nS as shown in FIG.
same as below).

FIG. 3 (A) must not be used in the present invention.
It is a figure showing an example of a violation design. “Dummy column” = 1111,
It is assumed that “compare sequence” = 0101. That is, in the design example of FIG. 3, the preamble portion is constituted by 8 chips of 11110101. When this data is transmitted, the receiving side prepares a “comparison target column” having the same chip as the “compare column” shown in FIG. 3B. ~ Show how the receiving side is stored in the data receiving buffer, the receiving side compares the receiving buffer with the "comparison target column",
The shift is performed for each chip in order.

At this time, if the undefined data "X" in the reception buffer is undefined data = 010, the reception buffer in this state becomes the same chip row as the "comparison target row", and Is mistaken for a frame synchronization, and is recognized as a start flag from the next chip row, so that correct synchronization cannot be achieved. That is, this design must not be performed such that the same chip row as the "compare comparison row" appears in the reception buffer before all the "compare rows" appear.

FIG. 4 is an explanatory diagram in which a "dummy column" is required in the preamble portion of the present invention. Without "dummy columns"
In the case of design with only "Compare column", "Compare column"
= 0110. That is, in the example of FIG. 4A, the preamble portion is constituted by four chips of 0110. When this data is transmitted, the receiving side prepares a “comparison target column” having the same chip as the “compare column” shown in FIG. 4B. Indicate that the receiving side is stored in the data receiving buffer, and the receiving side compares the receiving buffer with the "comparison target column" and shifts the order in units of one chip.

At this time, if the undefined data “X” in the reception buffer is undefined data = 011, the reception buffer in this state becomes the same chip row as the “comparison target row”, and Is mistaken for a frame synchronization, and is recognized as a start flag from the next chip row, so that correct synchronization cannot be achieved. Therefore,
Even if the correct "compare column" of the present invention shown in FIG. 2 is used, the frame cannot be properly synchronized without the "dummy column". Therefore, "dummy columns" are necessary.

As shown in FIG. 1, the start flag section of the present invention requires 32 chips of the conventional start flag. However, since the frame is synchronized at the end of the preamble section, the next start flag is One of 12 types of chips not used as data is used. Since the chip sequence used here does not represent data, the receiving side can recognize the chip sequence and then recognize the subsequent data part. Accordingly, the reduction of the transmission time per frame is {(32-4) / 4} × 500 nS = 3.5 μS.

In the stop flag section of the present invention, as shown in FIG. 1, 32 chips of the prior art stop flag were required, but in the present invention, any one of 12 types of chips not used as data is used. . Since the chip sequence used here does not represent data, the receiving side can recognize the chip sequence and recognize the end of the frame. Accordingly, the reduction of the transmission time per frame is {(32-4) / 4} × 500 nS = 3.5 μS.

As can be seen from the above, in the present invention,
The transmission time per frame can be reduced by 31 + 3.5 + 3.5 = 38 μS, so that the transmission efficiency can be improved as compared with the prior art.

FIG. 5 is a diagram showing all the design examples of the preamble part according to the present invention.

FIGS. 6A and 6B are schematic functional block diagrams of an embodiment of the present invention. FIG. 6A is a block diagram of a transmitting unit, and FIG. 6B is a block diagram of a receiving unit. Transmission data from the host bus 1 to which a CPU (not shown) or the like is connected is supplied to the quaternary PPM unit 2, subjected to PPM processing, frame-formatted, converted into an optical signal by the LED 3, and transmitted.

The quaternary PPM unit 2 includes a frame format forming unit 21 and a dummy column and compare column generating unit 2.
2, a start flag section and a stop flag section generation section 2
3 are provided. In the dummy column and compare column generating unit 22, one of the combinations of the chip patterns shown in FIG. 5 is generated in advance. In the start flag section and the stop flag section generating section 23, a 4-chip pattern not used for the data section is generated in advance. In the frame format forming section 21, these chip patterns are frame-formatted together with the quaternary PPM data and output.

In the receiving section, an infrared signal having a quaternary PPM-converted frame format is converted into an electric signal by the light receiving element 4 and introduced to a demodulating section (4-level PPM) 5. In the demodulation unit 5, the frame synchronization is performed by the frame synchronization unit 51. At this time, the “comparison target column” is compared with the data pattern in the data reception buffer (not shown), so that the frame is synchronized. Synchronization takes place. When the start flag section is detected after the frame synchronization is established in this way, the quaternary PPM demodulation of the subsequent data section is performed, and the demodulated data is supplied to the host bus 1.

[0029]

As described above, according to the present invention, it is possible to reduce the number of chips by 304 chips as compared with the conventional frame format. Therefore, it is necessary to transmit (304 chips / 4) × 500 ns = 38 μS per frame. There is an effect that time can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a frame format according to the present invention.

FIG. 2 is a diagram illustrating a design example of a preamble section according to the embodiment of the present invention.

FIG. 3 is a diagram showing an example of a violation design of a preamble part according to the present invention.

FIG. 4 is an explanatory diagram in which a dummy column is required in a preamble part according to the present invention.

FIG. 5 is a diagram showing all examples of a preamble section according to the present invention.

FIG. 6 is a schematic block diagram of an embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a conventional IrDA standard frame format.

FIG. 8 is a diagram illustrating quaternary PPM of a data part in the frame format of FIG. 7;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 host bus 2 4-level PPM 3 LED (light emitting diode) 4 light receiving element (photodiode) 5 demodulation unit 21 frame format formation unit 22 dummy column and compare column generation unit 23 start flag and stop flag generation unit 51 frame synchronization unit

Claims (5)

[Claims] 1. A frame format having a preamble part, a start flag part, a data part, and a stop flag part in this order, wherein one symbol of the data part is 4 symbols.
An infrared communication system represented by a 4-chip pattern of a value PPM (Pulse Position Modulation), wherein a 4 × 2 chip pattern other than the chip pattern of the data section is assigned to the preamble section, and the start flag section and the stop An infrared communication system, wherein four chip patterns other than the chip pattern of the data part are assigned to the flag part. 2. The preamble section comprises a 4-chip dummy column, followed by a 4-chip compare column,
2. The infrared communication system according to claim 1, wherein the comparison sequence is subjected to comparison processing with a comparison target sequence on a receiving side. 3. A frame format having a preamble section, a start flag section, a data section, and a stop flag section in this order, wherein one symbol of the data section is 4 symbols.
An infrared communication system represented by a 4-chip pattern of a value PPM (Pulse Position Modulation), wherein a 4 × 2 chip pattern other than the chip pattern of the data section is assigned to the preamble section, the start flag section and the stop. An infrared communication system comprising transmitting means for allocating and transmitting four chip patterns other than the chip pattern of the data part to the flag part, respectively. 4. The preamble section includes a 4-chip dummy column and a 4-chip compare column following the dummy column.
4. The infrared communication system according to claim 3, wherein the comparison sequence is subjected to comparison processing with a comparison target sequence on a receiving side. 5. A comparison means for receiving a frame format signal from the transmission means and comparing the four-chip compare string following the dummy string with the comparison target string, and comparing the four-chip compare string with the comparison target string. 5. The infrared communication system according to claim 4, further comprising a receiving unit for recognizing a chip pattern subsequent to the detected start flag as the start flag.