JPH11177530A - Low speed frequency hopping spread spectrum communication method and radio communication system using the communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and quickly improve the communication quality by checking the communication quality of a hopping pattern and changing the hopping pattern into the auxiliary one at all stations if an inferior communication state is decided at least at one station. SOLUTION: The auxiliary hopping patterns including the communication fault countermeasure hopping patterns are previously set at a radio master station 11 and plural radio slave stations 12 forming a radio zone Z1 in addition to the current hopping patterns respectively. Under such conditions, the low frequency hopping spread spectrum communication is carried out between the station 11 and the stations 12 based on those hopping patterns. The communication quality of the current hopping patterns are periodically checked, and the current hopping patterns are automatically changed into the auxiliary ones at all stations if an inferior communication state is decided at least at one station.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low frequency hopping spread spectrum communication method and a radio communication system using this communication method.

[0002]

2. Description of the Related Art One wireless master station and one or more wireless slave stations form a wireless zone, and the wireless master station and the wireless slave stations communicate with each other in this wireless zone. Is a low frequency hopping spread spectrum communication method in which all the stations perform communication while switching the use frequency according to a common hopping pattern. This low-speed frequency hopping spread spectrum communication method is a method in which a carrier frequency operates at a switching speed lower than the bit speed of an information signal, and a plurality of bits are transmitted by one carrier. As a wireless access method, CSMA / CA (Carrier Sense Multip
le Access / Collision Avoidance). According to the CSMA / CA method, when a wireless slave station intends to transmit to a wireless master station, it is checked whether there is another wireless slave station transmitting in the same zone. If it waits for a random time, it is checked again. Generally, when an error occurs, retransmission is performed.

Conventionally, in a radio communication system adopting such a low-speed frequency hopping spread spectrum communication method, a system administrator selects an appropriate pattern from several types of hopping patterns prepared in advance and selects an appropriate pattern within the same radio zone. Set to each station. Then, after operating the system for a certain period, a log such as the communication history of each station is acquired, and the log is analyzed to recognize the communication quality. When the quality is poor, the communication quality is improved by resetting to another hopping pattern.

[0004] The frequency band used in low-speed frequency hopping spread spectrum communication is usually 2.471.
GHz (gigahertz) to 2.497 GHz,
A radio wave generated from a high-frequency generator such as a microwave oven is one that can be an interfering radio wave in this frequency band. FIG. 11 shows the relationship between the noise level (vertical axis) and the frequency (horizontal axis) by the high frequency generator. As shown in the figure, the high-frequency generation device uses a frequency band (2.471 GHz to 2.497) used in low-speed frequency hopping spread spectrum communication.
GHz band) (lower band: 2.
471 GHz to 2.484 GHz).

For this reason, in an environment in which a high frequency generator such as a microwave oven is installed, such as a supermarket or a convenience store, a wireless POS (PoPo) using a low-speed frequency hopping spread spectrum communication system is used.
When an int Of Sales (point-of-sale information management) system is constructed, the frequency of the upper half band (upper band: 2.484 GHz to 2.497 GHz) in which the influence of radio waves from the high frequency generator is as small as possible is set as a hopping pattern. By selecting a pattern that has been used a lot, it has been attempted to obtain as good a communication quality as possible.

[0006]

However, in a conventional wireless communication system employing a low-speed frequency hopping spread spectrum communication method, a log such as a communication history is acquired for each wireless station in the same wireless zone and analyzed. Otherwise, the communication quality of the slow frequency hopping spread spectrum communication based on the current hopping pattern cannot be recognized.

[0007] Further, when the current hopping pattern is changed to another hopping pattern due to poor communication quality, it is necessary to manually re-set the pattern for every station in the wireless zone one by one. It had been.
Therefore, the burden on the system administrator is large until a good communication quality can be established, and a quick response cannot be taken.

Further, even if good communication quality can be ensured once, the communication quality may be deteriorated because a high frequency generator such as a microwave oven is installed in a wireless zone. The administrator has to reset the hopping patterns of all the stations in the wireless zone to hopping patterns using frequencies in a band where the influence of radio waves from the high frequency generator is small.

The present invention has been made in view of such circumstances, and a first object of the present invention is to automatically recognize the communication quality of low-frequency hopping spread spectrum communication based on the current hopping pattern, and to make it worse. In this case, a low frequency hopping spread spectrum communication method capable of easily and quickly improving communication quality by automatically changing to another hopping pattern and a wireless communication system using this communication method are provided. Things.
The second object is that when it is recognized that the communication quality of the low-speed frequency hopping spread spectrum communication based on the current hopping pattern is poor due to radio waves from the high-frequency generator, the high-frequency generation is automatically performed. A low frequency hopping spread spectrum communication method and a wireless communication system using this communication method that can be changed to a hopping pattern that is less affected by radio waves from the generator and that can also easily and quickly improve communication quality. It is something to offer.

[0010]

In order to achieve the first object, a low frequency hopping spread spectrum communication method according to the present invention is provided in which a wireless master station and all wireless slave stations in a wireless zone have a backup hopping pattern. And check the communication quality of the current hopping pattern,
If it is determined that the communication state is bad at one of the stations, the hopping pattern is changed to the spare hopping pattern at all the stations.

In order to achieve the second object,
The low-speed frequency hopping spread spectrum communication method according to the present invention is used for a communication failure countermeasure in which a wireless master station and all wireless slave stations in a wireless zone use only frequencies in a frequency band in which the influence of a communication failure by a high-frequency generator is small in advance. The hopping pattern is held, and the communication quality is checked for each frequency of the current hopping pattern. When a frequency with a bad communication state is determined, it is determined whether or not the frequency is a frequency in a frequency band where the influence of the communication failure by the high frequency generator is large. When it is determined that at least one station determines that the frequency is in a frequency band in which the influence of the communication failure due to the high-frequency generator is large, the hopping pattern is changed to the communication failure countermeasure hopping pattern in all the stations. Things.

In order to achieve the first object,
In the wireless communication system according to the present invention, the wireless master station and all the wireless slave stations in the wireless zone acquire and store the information on the communication quality of the current hopping pattern and the spare pattern holding means for holding the spare hopping pattern. Communication quality information storage means; quality determination means for determining a communication state based on information related to communication quality stored by the storage means; and a hopping pattern for storing a hopping pattern when the communication state is determined to be poor by the determination means. And a pattern changing means for changing to the spare hopping pattern held by the above.

Further, in order to achieve the second object,
In the wireless communication system of the present invention, the wireless master station and all wireless slave stations in the wireless zone hold a communication failure countermeasure hopping pattern using only a frequency in a frequency band in which the influence of the communication failure by the high frequency generator is small. A preliminary pattern holding unit, a communication quality information storage unit that acquires and stores information on communication quality for each frequency of the current hopping pattern, and a frequency of the current hopping pattern based on the communication quality information for each frequency stored by the storage unit. A quality discriminating means for discriminating a frequency in which the communication condition is bad, and judging whether or not the frequency determined to be in a bad communication condition by the discriminating device is a frequency in a frequency band in which the influence of the communication failure by the high frequency generator is great Frequency judging means, and the frequency judging means has a large influence of a communication failure by the high frequency generator. When it is determined that the frequency band is obtained and a pattern changing means for changing the hopping pattern to a communication failure countermeasure hopping pattern held by said preliminary pattern holding means. The frequency used in the hopping pattern for communication failure countermeasures is 2.
This is a frequency in a frequency band of 484 GHz or more.

The wireless master station has means for notifying the change of the pattern to all wireless slave stations when the hopping pattern is changed to the communication failure countermeasure hopping pattern by the pattern changing means. It is preferable that each wireless slave station having received the notification has means for changing the hopping pattern to the hopping pattern held by the spare pattern holding means.

Further, each wireless slave station has means for notifying the wireless master station of the change of the pattern when the hopping pattern is changed to the communication failure countermeasure hopping pattern by the pattern changing means. Upon receiving a pattern change notification from the station, the apparatus has means for changing the hopping pattern to the hopping pattern held by the spare pattern holding means and for notifying the change of the pattern to all wireless stations other than the wireless station of the notification source. Preferably, each wireless slave station that has received the pattern change notification from the wireless master station has means for changing the hopping pattern to the hopping pattern held by the spare pattern holding means.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram. One wireless master station 11 and a plurality of wireless slave stations 12 (12-1, 12-1) are shown.
-2,..., 12-n) to form one wireless zone Z1.
Wireless master stations 21 and a plurality of wireless slave stations 22 (22-1, 2
2-2,... 22-n) form another wireless zone Z2.

As shown in FIG. 3, each of the wireless master stations 11, 21 and each of the wireless slave stations 12, 22 are provided with a main board 30.
In addition, the CPU (Central Processing)
Unit) 31, a ROM (Read Only Memory) storing program data and the like for the CPU 31 to control each unit.
moly) 32, RAM (Random Access Memory) 3 forming various memories such as a memory for storing transmission / reception data
3. A clock circuit 34 composed of an IC (Integrated Circuit) for measuring the date and time, a DMA (Direct Memory Access) controller 35, and a communication controller 3 for controlling data communication with an external device (not shown) connected by a signal cable.
6, a timer circuit 37 composed of an IC, an operation unit 38 provided with switches, an input port 39 for receiving a signal from the operation unit 38, a display 40, an output port 41 for outputting a display signal to the display 40, EPROM (Erasable Progr
ammable Read Only Memoly) 42, serial I / O (In)
put / Output) 43 and the like. And the C
PU31, ROM32, RAM33, clock circuit 34, D
MA controller 35, communication controller 36, timer circuit 37, input port 39, output port 41, EPRO
The M42 and the serial I / O 43 are electrically connected by a bus line 44.

A wireless controller 45 is provided outside the main board 30. The wireless controller 45 is connected to the bus line 44 and to the serial I / O 43. An antenna 46 is provided to the wireless control unit 45.
Are connected.

Each of the radio base stations 11 and 21 and each of the radio slave stations 12 and 22 having such a configuration are connected between the radio base stations 11 and 21 and each of the radio slave stations 12 and 22 for each of the radio zones Z1 and Z2. The low frequency hopping spread spectrum communication is performed by periodically switching the use frequency according to a predetermined hopping pattern. Hopping pattern is
For example, 23 types of hopping frequencies f1 to 23 determined in a frequency band from 2.471 GHz to 2.497 GHz.
Several kinds of hopping frequencies are selected from f23 for each wireless zone and are created by allocating a switching order. By the way, in this embodiment, all the wireless stations 11 and 12 forming one wireless zone Z1 are connected to each other as shown in FIG.
Hopping frequencies f15, f3, f9, f18, f
4, f12, f2, f20, f13, f7 are selected, and a hopping pattern P1 to which hopping orders T = 1 to 10 are assigned in that order is set and stored in the EPROM 42, and the used frequency is periodically switched according to the hopping pattern P1. Slow frequency hopping spread spectrum communication shall be performed. Also, as shown in FIG. 2B, all the wireless stations 21 and 22 forming the other wireless zone Z2 have ten hopping frequencies f10, f18, f4, f13, f22, f7,.
f20, f15, f8, and f2 are selected and the hopping pattern P2 to which the hopping orders T = 1 to 10 are assigned in that order is set and stored in the EPROM 42, and the frequency used is periodically switched in accordance with the hopping pattern P2 to perform the low-speed hopping spectrum. Spread communication shall be performed. In addition,
Between the adjacent radio zones Z1 and Z2, each hopping pattern P is set so that the same frequency is not used at the same time.
1 and P2 are synchronized.

Each of the wireless master stations 11 and 21 and the wireless slave stations 12 and 22 stores spare hopping patterns P3, P4,... Separately from the hopping patterns P1 and P2 in the EPROM 42 as spare pattern holding means. A plurality of settings are stored. Here, as shown in FIG. 4, at least one of the preliminary hopping patterns P3, P4,.
The pattern (P3 in FIG. 4) has a frequency (f) of a frequency band (2.484 GHz to 2.497 GHz) in which the influence of a communication failure due to a high frequency generator such as a microwave oven is small.
12 to f23) are used as hopping patterns for communication failure countermeasures. The spare hopping patterns P3, P4,... Of the wireless master station 11 and each wireless slave station 12 in the wireless zone Z1 and the wireless master station 2 in the wireless zone Z2
1 and the spare hopping patterns P3, P4,...
2, different patterns are set so as not to use the same hopping pattern.

Further, as shown in FIG. 5, each of the radio base stations 11 and 21 and each of the radio slave stations 12 and 22 acquire and store information on the communication quality of the current hopping pattern, as shown in FIG. The hopping order T (1
10) a transmission count memory 51 for counting the number of message transmissions using the hopping frequency in that order, a retry count memory 52 for counting the number of retries at the time of message transmission for each hopping order T; A maximum retry count memory 53 for storing the maximum number of retries at the time of one message transmission for each hopping order T, and an error count memory 54 for counting the number of communication error occurrences per monitoring time described later for each hopping order T And the RAM 33
Is formed. The error count memory 54
, An area for a continuous error flag that is set to “1” when a communication error has occurred and an area for counting the number of continuous error occurrences are formed.

Thus, each of the radio base stations 11 and 21 and each of the radio substations 12 and 22 are provided with a rank counter T (maximum value 1) which counts up at a predetermined switching frequency of the used frequency.
0), and the CPU 31
The transmission or reception process is performed using the hopping frequency of the hopping order corresponding to. Then, the program is configured to execute the post-transmission processing shown in the flowchart of FIG. 6 every time the transmission processing is completed. That is, CPU
For example, when a message transmission operation to the partner station occurs due to data input from an external device connected via the communication controller 36, the frequency counter 31 corresponds to the rank counter T among the frequencies constituting the hopping patterns P1 and P2. A message is transmitted to the partner station using the frequency of the hopping order.
At this time, if an ACK response cannot be received from the partner station within a fixed time of several ms and transmission fails, retry is repeated at the same frequency. Then, if the transmission of the message succeeds or the retry is performed up to the limit number of times (16 times in this embodiment) but fails, the processing after the end of the transmission is started.

First, as ST (step) 1, the number of transmissions of the hopping order corresponding to the order counter T on the transmission count memory 51 is incremented by one. In step ST2, the number of retries at the time of transmitting the current message is added to the number of retries in the hopping order corresponding to the order counter T in the retry number counting memory 52. Next, as ST3, the maximum number of retries of the hopping order corresponding to the order counter T is read from the maximum number of retries memory 53 and is compared with the number of retries at the time of transmitting the current message. As a result, if the number of retries at the time of this message transmission exceeds the maximum value of the number of retries (YES in ST4), the number of retries of the hopping order corresponding to the order counter T in the maximum number-of-retries memory 54 in ST5. The maximum value is changed to the number of retries at the time of this message transmission, and the processing after the transmission is completed. If the number of retries at the time of this message transmission does not exceed the maximum number of retries (NO in ST4), the process after the end of the transmission ends without updating the maximum retry number memory 54.

The wireless master stations 11 and 21 and the wireless slave stations 12 and 22 have a program so that the CPU 31 periodically executes the communication error determination processing shown in the flowchart of FIG.

That is, the CPU 31 responds to the input of an interrupt signal generated each time a predetermined judgment time (for example, the time required for one cycle of the hopping pattern) set by the timer circuit 37 is counted. To start. First, the temporary counter n is temporarily reset to "0" in ST1, and then the temporary counter n is counted up by "1" in ST2. Next, as ST3, it is determined whether or not the temporary counter n has exceeded the maximum ranking "10" of the hopping pattern. If not exceeded, the transmission number counting memory 5 is set as ST4.
1. Data of the hopping order corresponding to the temporary counter n from the retry count memory 52 and the retry maximum memory 53, that is, the number of transmissions t, the number of retries r, and the number of retries at the hopping frequency to which the hopping order is assigned. Read the maximum value m.

Thereafter, in step ST5, it is determined whether or not the maximum value m of the number of retries is the maximum number of retries "16". Then, the maximum value m of the number of retries is set to the limit number “16”.
If it is smaller, the average number of retry occurrences r / t per transmission is calculated as ST6, and the average number of retry occurrences r / t is set to a set value (in this embodiment, "1").
0 ”) is determined. If the value does not exceed the set value "10", the process returns to ST2, where the temporary counter n is counted up by "1", and the number of transmissions t and t in the hopping order corresponding to the temporary counter n is calculated.
The number of retries r and the maximum number of retries m are read, and the determination processing in ST5 and ST6 is executed.

On the other hand, when the maximum number m of retries matches the maximum number of retries “16” in the judgment processing of ST5, or the average number of retries r / t exceeds the set value “10” in the judgment processing of ST6. In step ST7, the number of times of occurrence of an error in the hopping order corresponding to the temporary counter n of the error number counting memory 54 is incremented by one in step ST7. Thereafter, the process returns to ST2, where the temporary counter n
Is counted up by “1”, and the temporary counter n
Are read, the number of times of transmission t, the number of retries r, and the maximum value of the number of retries m of the hopping order corresponding to
Is performed.

Thus, for each hopping order, the presence or absence of a communication error is determined from the number of transmissions t, the number of retries r, and the maximum value m of the number of retries at the frequency corresponding to the hopping order. After confirming that the maximum ranking "10" has been exceeded,
This communication error determination processing ends.

Further, each of the radio base stations 11 and 21 and each of the radio slave stations 12 and 22 have a program so that the CPU 31 periodically executes the communication quality monitoring processing particularly shown in the flowchart of FIG. That is, the CPU 31
7, the communication quality monitoring process is started in response to the input of an interrupt signal generated every time a predetermined monitoring time (> judgment time) set in advance is counted.

First, at step ST1, the temporary counter n is temporarily reset to "0", and then at step ST2, the temporary counter n is counted up by "1". Next, as ST3, it is determined whether or not the temporary counter n has exceeded the maximum ranking "10" of the hopping pattern. If not exceeded, the number of times of error occurrence e of the hopping order corresponding to the temporary counter n is read from the error number counting memory 54 as ST4. Here, if the error occurrence count e is “0” in ST5, the process returns to ST2.

On the other hand, if the error occurrence number e is equal to or greater than "1", the continuous error flag p and the continuous error number q of the hopping order corresponding to the temporary counter n are stored in the error number counting memory 54 in ST6. Read. Here, if the continuous error flag p has been reset to "0" in ST7, the continuous error flag p of the hopping order corresponding to the temporary counter n of the error number counting memory 54 is set to "1" in ST8. At the same time, the continuous error count q is set to “1”. Thereafter, the process returns to ST2.

On the other hand, when the continuous error flag p is set to "1" in ST7, the number of continuous errors q in the hopping order corresponding to the temporary counter n of the error number counting memory 54 is incremented by one in ST9. Later, ST
As 10, it is determined whether or not the number of continuous errors q has reached a set value (in this embodiment, “5”) at which the communication quality of the current hopping pattern is considered to be poor. When the number of continuous errors q is less than the set value "5", the process returns to ST2.

In this way, it is determined whether or not a communication error has occurred for each frequency constituting the hopping pattern in accordance with the hopping order (ST4, ST5). If an error has occurred, it is continuously generated from the communication quality monitoring processing up to now. (ST6, 7), and if they occur continuously, it is determined from the number of consecutive occurrences whether or not the communication quality of the current hopping pattern is poor (ST9, 1).
0). If it is determined that the communication quality of the current hopping pattern is good, the number of errors in each hopping order in the error number counting memory 54 is cleared to "0" in ST11, and the current communication quality monitoring process is performed. finish.

On the other hand, if the number of continuous error occurrences has reached the set value "5" in at least one of the hopping frequencies constituting the hopping pattern in ST10, the communication quality of the current hopping pattern is poor. In step ST12, the hopping frequency f at which the number of continuous errors has reached the set value "5" is changed to the lower band frequencies (f1 to f1) which are greatly affected by the high frequency generator.
It is determined whether 1) or the frequency of the upper band (f12 to f23) where the influence of the high frequency generator is small. In the case of the frequency of the lower band, high-frequency heating using only the frequency of the upper band (f12 to f23) among the preliminary hopping patterns P3, P4,. A process for changing to a hopping pattern P3 for device countermeasures is executed. On the other hand, in the case of the frequency of the upper band, a process of changing the current hopping pattern to a spare hopping pattern P4 other than the hopping pattern P3 for high-frequency heating device countermeasures is executed in ST14.

Thereafter, as ST15, the error count memory 54 is initialized (error occurrence count, continuous error count = 0, continuous error occurrence flag = reset "0"), and the current communication quality monitoring process is terminated. . Here, in the communication quality monitoring process, the process of ST1 to ST10 constitutes a quality judging unit, the process of ST12 constitutes a frequency judging unit, and the processes of ST13 and ST14 constitute a pattern changing unit.

Here, the content of the hopping pattern changing process differs between the radio base stations 11 and 21 and the radio slave stations 21 and 22. FIG. 9 shows a hopping pattern change process of the wireless master stations 11 and 21.
1 and 21 determine whether the own station enters the hopping pattern change process by executing the communication quality monitoring process (YE in ST1).
S), wireless slave stations 12, 2 in the same wireless zone Z1, Z2
If the change notification message of the hopping pattern is received from No. 2 (YES in ST2), the pattern change process is started.

First, when the hopping pattern change processing is started in the own station, a hopping pattern including information designating whether to change to a hopping pattern for high-frequency heating measures or another preliminary hopping pattern in ST3. Create a change notification message. Then, in ST4, this change notification message is transmitted to all the wireless stations 12 and 22 in the same wireless zones Z1 and Z2 by low-speed frequency hopping spread spectrum communication. Thereafter, it waits for a response from all the wireless slave stations 12 and 22.

Here, all the wireless slave stations 1 within a certain time period
If an ACK response indicating successful reception of a message is received from any one of the terminals 2 and 22 (YES in ST5), or if the standby time has timed out (YES in ST6), the current hopping pattern P1, P2 is changed to a high frequency heating countermeasure hopping pattern P3 or another preliminary hopping pattern P4.

On the other hand, if a hopping pattern change notification message is received from any of the wireless stations 12 and 22 in the same wireless zone Z1 or Z2, the process proceeds to step ST8 where the wireless message is transmitted from the wireless station 12 as the source of the notification message. , 22 after transmitting an ACK response indicating successful message reception, the same processing as in ST4 to ST7 is performed. That is, the corresponding change notification message is transmitted to all the wireless stations 12 and 22 in the same wireless zone Z1 and Z2. Then, all the wireless slave stations 12,
22 receives an ACK response indicating successful message reception,
When the waiting time has timed out, the current hopping patterns P1 and P2 are changed to the high-frequency heating countermeasure hopping pattern P3 or another preliminary hopping pattern P4 notified in the received message.

FIG. 10 shows a hopping pattern change process of the wireless slave stations 12 and 22.
Is to execute the hopping pattern change processing in the own station by executing the communication quality monitoring processing (YES in ST1), or send the hopping pattern change notification message from the wireless master stations 11 and 21 in the same wireless zones Z1 and Z2. If received (S
T2 (YES), this pattern change process is started.

First, when the hopping pattern change processing is started in the own station, a hopping pattern including information for specifying whether to change to a hopping pattern for high-frequency heating measures or another preliminary hopping pattern in step ST3. Create a change notification message. Then, in ST4, this change notification message is transmitted to the wireless master stations 11 and 21 in the same wireless zones Z1 and Z2 by low-speed frequency hopping spread spectrum communication. After a while, this wireless master station 1
Wait for a response from 1,21.

Here, the radio base stations 11 and 21 are set within a predetermined time.
If an ACK response indicating successful message reception has been received from the wireless base station 11 (YES in ST5), the mobile station 11
It waits for a change notification message from 21 to be transmitted.
If the change notification message is received within a predetermined time (YES in ST7), the process proceeds to ST8, in which the wireless master station 11,
After transmitting the ACK response to 21, the mobile station changes the hopping patterns P1 and P2 being used in the own station to the high-frequency heating countermeasure hopping pattern P3 or another preliminary hopping pattern P4 notified in the received message in ST9.

Note that, after transmitting the change notification message to the radio base stations 11 and 21 in ST4, if an ACK response cannot be received from the radio base stations 11 and 21 even after a certain period of time (ST110 YES). , And the wireless master station 11 of ST6,
If the change notification message from the wireless master stations 11 and 21 has not been received from the wireless master stations 11 and 21 even after the lapse of a predetermined time in the change notification message waiting state from ST21 (YES in ST11), the hopping pattern is changed. And the current process ends.

On the other hand, when hopping pattern change notification messages are received from the wireless master stations 11 and 21 in the same wireless zones Z1 and Z2, the same processing as in ST8 to ST9 is performed. That is, ACK is sent to the radio base stations 11 and 21.
After transmitting the response, the hopping patterns P1 and P2 used in the own station are changed to the hopping pattern P3 for high-frequency heating countermeasure notified by the received message or another preliminary hopping pattern P4.

As described above, in the present embodiment, for example, one radio base station 11 and a plurality of radio slave stations 12 forming the radio zone Z1 are provided with communication failures separately from the current hopping pattern P1. Preliminary hopping patterns P3, P4,... Including countermeasure hopping patterns are set. In this state, the wireless master station 11 and each wireless slave station 12 perform low-frequency hopping spread spectrum communication according to the hopping pattern P1. At this time, the communication quality of the current hopping pattern P1 is periodically checked, and if it is determined that the communication state is poor in at least one station, the current hopping pattern P1 is determined in all the stations.
Are automatically changed to the spare hopping patterns P3, P4,.

Specifically, the current hopping pattern P
The number of transmissions t, the number of retries r, and the maximum value of the number of retries m are managed for each frequency of 1 and the presence or absence of a communication error is periodically determined for each frequency from these values. When a frequency at which the number of consecutive occurrences of the communication error exceeds 5 is confirmed, it is recognized that the communication quality of the current hopping pattern P1 is poor. At this time, whether the frequency at which the number of consecutive occurrences of the communication error exceeds 5 is the frequency of the lower band (f1 to f11) where the influence of the communication failure by the high frequency generator is large, or the upper band (f12 to f23) with a small influence Is determined. In the case of the frequency of the lower band, the hopping pattern to be used in the radio base station 11 and each radio slave station 12 is the current hopping pattern P
1 is simultaneously changed to a communication failure countermeasure hopping pattern P3. On the other hand, in the case of the frequency of the upper band, the hopping pattern to be used in the wireless master station 11 and each wireless slave station 12 is the current hopping pattern P1.
Are simultaneously changed to other preliminary hopping patterns P4. Note that one wireless master station 21 and a plurality of wireless slave stations 22 forming the other wireless zone Z2 operate in the same manner as described above.

As described above, according to the present embodiment, the communication quality of the low-speed frequency hopping spread spectrum communication based on the current hopping pattern is automatically recognized, and if it is bad, the hopping pattern is automatically changed to another hopping pattern. This eliminates the need for the system administrator to analyze the log such as the communication history for each wireless station to check the communication quality. Further, even when the hopping pattern is changed due to poor communication quality, the system administrator does not need to take any trouble. Therefore, good communication quality can be easily and quickly established without imposing a burden on the system administrator.

When the deterioration of the communication quality of the low-speed hopping spread spectrum communication due to the current hopping pattern is caused by the radio wave from the high frequency generator, the influence of the radio wave from the high frequency generator is automatically applied. Since the hopping pattern P3 is changed to the small communication failure countermeasure hopping pattern, it is possible to quickly avoid a decrease in communication quality due to radio waves from the high frequency generator without burdening the system administrator.

In the above embodiment, the communication quality of the hopping pattern is evaluated from the average number of retries and the number of retries for each hopping frequency.
For example, the evaluation may be made only from the number of times of retry.
Alternatively, the evaluation may be performed based only on the average number of retry occurrences.
Further, it is needless to say that the set value “5” of the number of continuous errors for determining that the communication quality is bad and the set value “10” of the average number of retry occurrences for determining the communication error are not limited to these values. .

The communication quality monitoring process need not always be performed at regular time intervals, but may be performed only during a period considered necessary by the system administrator. In addition, it is needless to say that various modifications can be made without departing from the gist of the present invention, for example, by applying the present invention to a wireless communication system including one wireless zone or three or more wireless zones.

[0051]

As described in detail above, according to the present invention,
The communication quality of the low-frequency hopping spread spectrum communication based on the current hopping pattern can be automatically recognized, and when bad, the communication quality can be easily and quickly improved by automatically changing to another hopping pattern. A low-speed frequency hopping spread spectrum communication method and a wireless communication system using the communication method can be provided. Also,
If it is recognized that the cause of the poor communication quality of the low-speed frequency hopping spread spectrum communication by the current hopping pattern is due to radio waves from the high frequency generator,
A low frequency hopping spread spectrum communication method which can automatically change to a hopping pattern that is less affected by radio waves from a high frequency generator and can easily and quickly improve communication quality, and a communication method using this communication method. A wireless communication system can be provided.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention.

FIG. 2 is a view showing an example of a hopping pattern used in the embodiment.

FIG. 3 is a block diagram showing a main part of each wireless station constituting the embodiment.

FIG. 4 is a diagram showing an example of a preliminary hopping pattern stored in an EPROM of each wireless station.

FIG. 5 is a diagram showing main memory areas formed in a RAM of each wireless station.

FIG. 6 is a flowchart showing post-transmission processing performed by the CPU of each wireless station.

FIG. 7 is a flowchart showing a communication error determination process executed by a CPU of each wireless station.

FIG. 8 is a flowchart showing a communication quality monitoring process executed by a CPU of each wireless station.

FIG. 9 is a flowchart showing a hopping pattern change process executed by the CPU of each wireless master station.

FIG. 10 is a flowchart showing a hopping pattern changing process executed by the CPU of each wireless slave station.

FIG. 11 is a diagram showing a relationship between a noise level and a frequency by the high frequency generator.

[Explanation of symbols]

 Z1, Z2: wireless zone P1, P2: hopping pattern P3: hopping pattern for communication failure countermeasures P4: spare hopping pattern 11, 21: wireless master station 12, 22 ... wireless slave station 51: transmission count memory 52: retry count Memory 53: Maximum retry count memory 54: Error count memory

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Claims (6)

[Claims] 1. A wireless zone is formed by one wireless master station and one or more wireless slave stations, in which the wireless master station and the wireless slave stations follow a predetermined hopping pattern. When performing low-speed frequency hopping spread spectrum communication, the wireless master station and all wireless slave stations in the wireless zone hold a spare hopping pattern and check the communication quality of the current hopping pattern, A low frequency hopping spread spectrum communication method, characterized in that, when it is determined that the communication state is bad in all the stations, the hopping pattern is changed to the spare hopping pattern in all the stations. 2. A wireless zone is formed by one wireless master station and one or more wireless slave stations, and the wireless master station and the wireless slave stations are arranged in the wireless zone according to a predetermined hopping pattern. When performing low-speed frequency hopping spread spectrum communication, the wireless master station and all wireless slave stations in the wireless zone are used in advance for communication failure countermeasures using only frequencies in a frequency band in which the influence of communication failure by the high frequency generator is small. Holding the hopping pattern, and examining the communication quality for each frequency of the current hopping pattern, if the frequency of poor communication is determined, whether the frequency is a frequency of a frequency band in which the influence of communication failure by the high-frequency generator is large. Judge,
If at least one station determines that the frequency is in a frequency band in which the influence of the communication failure by the high frequency generator is large, the hopping pattern is changed to the communication failure countermeasure hopping pattern in all the stations. A low frequency hopping spread spectrum communication method characterized by the following. 3. A wireless zone is formed by one wireless master station and one or more wireless slave stations, and in the wireless zone, the wireless master station and the wireless slave stations follow a predetermined hopping pattern. In a wireless communication system that performs low-speed frequency hopping spread spectrum communication, a wireless master station and all wireless slave stations in the wireless zone each include a spare pattern holding unit that holds a spare hopping pattern and a communication quality of a current hopping pattern. Communication quality information storage means for acquiring and storing information; quality determination means for determining the communication state based on the communication quality information stored by the storage means; and hopping when the communication state is determined to be poor by the determination means Pattern changing means for changing a pattern to a spare hopping pattern held by the spare pattern holding means Wireless communication system, characterized by comprising a. 4. A wireless zone is formed by one wireless master station and one or more wireless slave stations, in which the wireless master station and the wireless slave stations follow a predetermined hopping pattern. In a wireless communication system that performs low-speed frequency hopping spread spectrum communication, a wireless master station and all wireless slave stations in the wireless zone are provided with communication failure countermeasures using only frequencies in a frequency band in which the influence of the communication failure by the high-frequency generator is small. A spare pattern holding unit for holding a hopping pattern for use, a communication quality information storage unit for acquiring and storing information on communication quality for each frequency of the current hopping pattern, and a communication quality information for each frequency stored by the storage unit. Quality determining means for determining a frequency having a bad communication state among the frequencies of the current hopping pattern; Frequency determining means for determining whether or not the frequency determined by the determining means to be in a poor communication state is a frequency in a frequency band where the influence of the communication failure by the high-frequency generator is large; and communication failure by the high-frequency generator by the determining means. And a pattern changing means for changing a hopping pattern to a communication failure countermeasure hopping pattern held by the spare pattern holding means when it is determined that the frequency is in a frequency band in which the influence of the above is large. 5. The wireless master station has means for notifying a change in pattern to all wireless slave stations when the hopping pattern is changed to a communication failure countermeasure hopping pattern by the pattern changing means. 5. The wireless communication system according to claim 3, wherein each of the wireless slave stations having received the change notification has a means for changing the hopping pattern to the hopping pattern held by the spare pattern holding means. 6. When each wireless slave station changes a hopping pattern to a communication failure countermeasure hopping pattern by a pattern changing means, the wireless slave station includes a unit that notifies the wireless master station of the change in the pattern, wherein the wireless master station includes: Means for changing the hopping pattern to the hopping pattern held by the spare pattern holding means upon receiving a pattern change notification from the wireless slave station, and for notifying the change of the pattern to all other wireless slave stations except the notification source wireless slave station 4. Each wireless slave station having received a pattern change notification from the wireless master station has means for changing a hopping pattern to a hopping pattern held by a spare pattern holding means. 5. The wireless communication system according to 4.