JPH0833022A - Modulator / demodulator for specified low power wireless transmission - Google Patents

Abstract

(57) [Abstract] [Purpose] Modulator / demodulator for specific low power wireless transmission that randomly selects an empty channel from a plurality of data channels for communication 0
At 1, a data channel with a high vacancy probability is selected, channel acquisition is accelerated, and communication time is shortened. [Structure] CPU3 at data channel selection (line connection)
When the randomly selected data channel CHA has a carrier (is not empty), the (high vacancy probability data channel selection means 3A) increments the carrier data channel count 4B of the channel CHA by 4 + 1. This addition is continued for a predetermined period (unusable data channel refresh interval) 5B, and the number of times 4B is the unusable data channel determination reference value 5
When it reaches C, this data channel CHA is registered as the unusable data channel 4C, and thereafter it is excluded from the channel selection targets. However, when the predetermined period 5B has elapsed, the number of times 4
After clearing the data of B and channel 4C, the same data channel selection operation as before is repeated from the beginning.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a radio equipment standard RCR.
The present invention relates to a modulator / demodulator for specific low-power wireless transmission (hereinafter abbreviated as wireless modem) that automatically switches channels based on a STD-17 line connection procedure. In the drawings, the same reference numerals indicate the same or corresponding parts.

[0002]

2. Description of the Related Art In an automatic channel switching system performed by a wireless modem of this kind in a radio equipment standard RCR STD-17 line connection procedure, it is prescribed that a data channel be automatically and randomly selected. (However, it is not defined as a range of data channels to be randomly selected.) Therefore, at the start of transmission, one of the nine channels CH1 to CH9 normally assigned as a data channel, which has not been selected, is sequentially randomized. Select to check the presence or absence of carrier radio waves (this radio wave detection is also called carrier sense), and if an empty data channel with no carrier is found for the first time, that data channel is determined as the data channel to be used and transmission is performed. Is going.

That is, when an empty data channel is searched for, if a radio wave is present in a randomly selected data channel, that is, if that channel is being used by a wireless modem of another station or there is noise (at the time of determining whether there is a carrier), that channel. Assuming that the channel is in use, one of the remaining channels is randomly selected, and such a random selection operation is repeated until a free channel is found, and a free channel is searched.

[0004]

However, when the wireless environment is bad such as a lot of noise and a large amount of traffic and the number of usable data channels is limited to a small number N (1-2), In the random selection method, the selection probability of usable channels is N / 9, and the probability of selecting usable channels in one data channel selection is low. For this reason, in the worst environment in which communication is possible, the only available channel is used by another system first depending on the timing, resulting in a situation in which communication cannot be performed.

For example, if only the channel CH5 of the nine data channels is an empty channel and the remaining eight channels are used by other stations of the fixed channel system with high probability or there is noise, automatic random selection is performed. If the authority wireless modem of the method and the wireless modem of another station try to connect to the line at the same time, both stations will have channels CH1 to CH.
Since the 9 data channels are automatically and randomly selected, the station that selects CH5, which is a free channel, earlier acquires the data channel. For this reason, the wireless modem of the authority may not be able to acquire the data channel, and communication may not be possible.

According to the present invention, even when the wireless environment is bad and the number of empty data channels is always small as described above, the communication time can be shortened by searching the empty data channels quickly and acquiring the data channels quickly. Planning and
An object of the present invention is to provide a modulator / demodulator for specific low-power wireless transmission that can reduce the probability of a situation where communication is not possible.

[0007]

In order to solve the above-mentioned problems, the wireless modem of the present invention uses a plurality of predetermined data channels at the start of data transmission (received together with a transmission command from the data terminal device 1 or the like). The operation of randomly selecting one unselected data channel from each (such as the wireless data channel 5A) is repeated to search for an empty data channel with no carrier, and data transmission is performed using the empty data channel searched for the first time. In a specific low power wireless transmission modulator / demodulator (wireless modem 01, etc.), for a predetermined period (unusable data channel refresh interval 5B, etc.)
For each time, the number of times a carrier for each randomly selected data channel was present (such as the number of data channels with carrier 4B) is integrated from 0, and this integrated number is a predetermined value (unusable data channel determination reference value 5C, etc.). ) Has been reached, means for excluding this data channel from being selected only during the relevant period (as the unusable data channel 4C etc.) (high availability probability data channel selection means 3A etc.)
Shall be provided.

[0008]

In the carrier sense of the data channel for searching for an empty data channel when the line is connected, the data channel judged to be present due to noise in use or due to noise is defined as "data channel with carrier" and carrier for each data channel. The number of times it is judged to be present is stored, and this number of times of storage is the "unusable data channel reference value".
When it exceeds the above, the carrier sense of the data channel is not performed from the time of the carrier sense of the next data channel, so that the carrier sense of only the data channel having a high free channel probability is performed. However, the number of times of storage is cleared to zero every predetermined period.

[0009]

1 is a block diagram of an embodiment of the present invention.
In the figure, 01 is a wireless modem, and 1 is a data terminal device for inputting and outputting commands and data to the wireless modem 01.
Further, in the wireless modem 01, 2 is a data input / output interface for inputting / outputting data to / from a data terminal device (interface is abbreviated as i / F), 3 is a CPU for frequency selection, comparison with a reference value, carrier sense, etc. 4 is a RAM for storing data 4A received from the data terminal device 1, number of data channels with carrier 4B, data of unusable data channel 4C, etc. 5 is wireless data channel 5
A, ROM for storing unusable data channel refresh interval 5B, unusable data channel determination reference value 5C, and various data necessary for control, 6 is for specific low power data transmission by data from data input / output i / F2 Reference numeral 7 is a wireless transmission device for transmitting radio waves of a radio band frequency, and 7 is a wireless reception device for receiving radio waves of a specific low power data transmission radio band frequency by data from the data input / output i / F 2. The high-vacancy probability data channel selection means 3A in the CPU 3 is a main functional part of the CPU 3 related to the present invention.

In FIG. 3, the wireless modem 01 is the data terminal device 1.
Is a flow chart showing an operation procedure when data is received from the device via the data input / output i / F2, and S1 to S3 indicate the steps. That is, when the received content is a transmission command including transmission data (S1, branch Y), CPU3
Performs data transmission according to the procedure shown in FIG. 2 (S2). On the other hand, in step S1, if the received content is data that does not accompany the transmission command, for example, the parameter for initial setting (S1, branch N), the CPU 3 stores the content in the RAM 4.

FIG. 2 is a flow chart showing the operation procedure of the CPU 3 (the high availability probability data channel selection means 3A thereof) at the time of data transmission, and S11 to S22 show the steps. Next, FIG. 2 will be described with reference to FIG. The CPU 3 reads from the ROM 5 and the RAM 4 the numbers of all the wireless data channels 5A to be selected defined by the RCR STD-17 and the numbers of the unusable data channels 4C (S11, S12). Then, the number of the unusable data channel 4C is omitted from the number of the wireless data channel 5A as the data channel to be selected (S13), and one of them is selected by the random number to select the current data channel (CH
A) (S14). Next, this time data channel (CH
The frequency data for A) is output to the wireless reception device 7 (S
15). Therefore, the wireless reception device 7 receives the wireless of the frequency of the data channel (CHA) to be selected based on the frequency data. As a result, the CPU 3 causes the wireless reception device 7
Further, the carrier presence / absence signal is received / determined (S16), and if there is no carrier (branch “none”), this data channel (CHA) is determined as the current communication data channel, and the process proceeds to step S21.

On the other hand, if there is a carrier (S16, branch "Yes"), the number of carrier data channels 4B of this data channel (CHA) in the storage area of the RAM 4 is incremented by 1 (S17). Then, the unusable data channel determination reference value (number of times) 5C is read from the ROM 5 (S1
8) Compare with the number of data channels with carrier 4B of the above-mentioned data channel (CHA). That is, it is checked whether the following relationship holds (S19).

[0013]

[Numerical formula 1] {Unavailable data channel determination reference value (number of times)
5C} ≦ {data channel number with carrier 4B of the previous data channel (CHA) 4B} If NO in this comparison (branch N), the process directly returns to step S11, and if YES (S19, branch Y), This data channel (CHA) is determined as the unusable data channel 4C, registered and stored in the RAM 4, and the process returns to step S11 to repeat the above operation from the beginning.

When the carrier is not detected in step S16 (branch "none") and the communication data channel is determined this time, the CPU 3 wirelessly receives the control channel frequency data defined by the RCR STD-17. It is output to the device 7 (S21). Therefore, the wireless reception device 7 receives the wireless of the control channel frequency based on the frequency data. As a result, the CPU 3 receives and determines the carrier presence signal from the wireless reception device 7 (S22), and if there is no carrier (branch “none”), starts data communication. That is, once
Through the communication at the frequency of the control data channel CH10, the partner device is informed that the normal communication (data communication) is performed by the current data channel (CHA), and then the regular data channel (CHA) is used by the normal frequency. Perform data communication.

If there is a carrier in this step S22 (branch "yes"), the process returns to step S11 and the above operation is repeated from the beginning. Further, the CPU 3 executes the procedure of FIG. 4 that compares the timer interrupt elapsed time with the unusable data channel refresh interval 5B in the ROM 5 at regular intervals. S31 to S33 indicate the steps. That is

[0016]

[Equation 2] (Unavailable data channel refresh interval 5
B) ≦ (elapsed time) (S31, branch Y), it is in the RAM4,
Each data of carrier data channel number 4B and unusable data channel 4C is cleared (S32, S3
3).

[0017]

According to the present invention, when searching for an empty data channel at the start of transmission, the data channel having a low empty probability is omitted from the selection target of the data channel. It can be selected, which allows the data channel to be acquired faster.

Further, by periodically clearing the information of the'unusable data channel 4C 'in which the data channel is registered as a non-selection target, it is possible to cope with a change in the wireless environment.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration as an embodiment of the present invention.

FIG. 2 is a flowchart showing a procedure of data transmission of the CPU of FIG.

FIG. 3 is a flowchart showing a procedure for receiving data from the data terminal device of the CPU of FIG.

FIG. 4 is a flowchart showing a procedure of timer interruption of the CPU of FIG.

[Explanation of Codes] 01 Wireless modem 1 Data terminal device 2 Data input / output i / F 3 CPU 3A High availability probability data channel selection means 4 RAM 4A Data received from data terminal 4B Number of data channels with carrier 4C Unusable data channel 5 ROM 5A Wireless data channel 5B Unusable data channel refresh interval 5C Unusable data channel determination reference value 6 Wireless transmitter 7 Wireless receiver

Claims (1)

[Claims] 1. At the start of data transmission, an unselected data channel is randomly selected from a plurality of predetermined data channels.
In the modulator / demodulator for specific low-power wireless transmission that repeats the operation of selecting one by one, searches for an empty data channel with no carrier, and transmits data using the empty data channel searched for the first time. The number of times that the carrier has existed for each data channel accumulated from 0, and when the accumulated number reaches a predetermined value, the data channel is excluded from the selection target only during the period. A specified low power wireless transmission modulator / demodulator.