JPH11220771A - Method and system for radio communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce time losses for transmitting and receiving data information by the transmission time of omitted beacon information by not transmitting beacon information at the transmission timing of beacon information during data transmission. SOLUTION: When a time out of a beacon timer is detected in a state without transmission data, a radio transmission frame of beacon information is radio-transmitted to respective radio slave stations 4a, 4b, 4c and 4d in the same radio zones Z1 and Z2 through a radio part. In such a case, it is recognized that a radio wave is not emitted to a present communication frequency band before the frame is transmitted. Then, the communication frequency is switched to a next frequency, in accordance with a hopping pattern which is set in a storage part. Beacon information which is radio-transmitted from radio master stations 2a and 2b at each beacon time out is not transmitted, when the beacon timer is timed out during the transmission of data information. In this way, communication efficiency of a data information cable enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a frequency hopping spread spectrum communication system (hereinafter abbreviated as FH system).
And a wireless communication system employing the method.

[0002]

2. Description of the Related Art FIG. 6 shows an example of a radio communication system employing a general FH system. In this system, two wireless master stations 2 are connected to a host device 1 that controls and controls the entire system.
a and 2b are connected by wire. In addition, wireless slave stations 4a, 4b, 4c, and 4d are connected to a plurality of data processing terminals 3 which are centrally managed by the host device 1, respectively. One wireless master station 2a and a plurality of wireless slave stations 4a,..., 4b form one wireless zone Z1, and one wireless master station 2b and a plurality of wireless slave stations 4c, 4c.
, 4d form another wireless zone Z2.

In this device, the radio base stations 2a and 2b and the radio substations 4a, 4b, 4c and 4d set a common hopping pattern with the counterpart stations forming the same radio zones Z1 and Z2, respectively. The wireless communication is performed with the partner station in the same wireless zone Z1, Z2 while changing the communication frequency in a time-division manner according to the hopping pattern. This wireless communication system is called an FH system, and usually uses a frequency in the 2.4 GHz band.

When the FH system is adopted, the radio base stations 2a and 2b and the radio stations 4a, 4b, 4c and 4d change the communication frequency in a time-division manner according to a common hopping pattern. Must now know which frequency of the hopping pattern to communicate with. Therefore, in order to synchronize the switching timing of the hopping pattern, conventionally, a timer that repeatedly measures the frequency switching cycle of the hopping pattern, a so-called beacon timer, is provided in the wireless master stations 2a and 2b. Then, each time the timer times out, the wireless master stations 2a and 2b transmit beacon information for synchronizing the switching timing of the hopping pattern to the same wireless zone Z1,
The broadcast is transmitted to all the wireless stations 4a, 4b, 4c and 4d in Z2 simultaneously. Further, the communication frequency is switched to the next frequency according to the hopping pattern. On the other hand, the wireless slave stations 4a, 4b, 4c, and 4d that have received the beacon information switch the communication frequency to the next frequency according to the hopping pattern based on the beacon information. In this way, the switching timing of both hopping patterns is synchronized.

[0005] However, even if the beacon timer times out and the transmission timing of the beacon information is reached, the wireless master stations 2a and 2b can communicate with the wireless slave stations 4 in the same wireless zone Z1 or Z2.
Beacon information cannot be transmitted while data information is being communicated with a, 4b, 4c, and 4d. Therefore,
In such a case, conventionally, the beacon information is transmitted after the communication of the data information is completed, and the next beacon information is transmitted at the next regular timing.

FIG. 7 shows an example of information transmission timing of the conventional wireless master stations 2a and 2b. In the figure, the symbol B of the transmission frame indicates the transmission frame of the beacon information, and the symbol D indicates the transmission frame of the data information. That is, the beacon timer that repeats the measurement of the fixed time T times out (TO).
Each time the wireless base stations 2a and 2b wirelessly transmit the transmission frame B of the beacon information [time points t1 and t3]. However,
When the beacon timer times out while transmitting the transmission frame D of the data information [time t2], the transmission frame B of the beacon information is wirelessly transmitted after the transmission of the transmission frame D is completed.

By the way, in order to avoid radio wave collision, each radio station checks whether a radio wave of that frequency has already been generated when performing radio transmission at an arbitrary frequency determined by a hopping pattern (carrier sense). ). If no radio wave of the corresponding frequency is detected, wireless transmission is performed. On the other hand, when the radio wave of the corresponding frequency is detected, it waits for a certain period of time, and tries to check the radio wave again. In this way, wireless transmission is performed after the radio wave of the corresponding frequency is no longer detected.

Therefore, in one wireless zone, the transmission time of the beacon information generated periodically is always occupied by the frequency, and the communication time of the data information in each wireless station is restricted accordingly.

[0009]

As described above, in this type of conventional wireless communication system, every time the beacon timer for repeatedly counting the frequency switching cycle of the hopping pattern times out, the wireless master station transmits a signal within the same wireless zone. Beacon information for synchronizing the hopping pattern switching timing is always transmitted to each wireless station, and during transmission of this beacon information, each wireless station could not transmit and receive data information. Was bad.

Accordingly, the present invention provides a radio communication method capable of improving the communication efficiency of data information limited by the transmission time of beacon information for synchronizing the switching timing of a hopping pattern, and a radio communication system employing this radio communication method. It is something to offer.

[0011]

According to a radio communication method of the present invention, a radio master station transmits beacon information to a radio slave station at a constant cycle, thereby synchronizing a hopping pattern between the radio master station and the radio slave station. In such a configuration, if there is data information to be transmitted to the wireless slave station, the wireless master station determines whether or not it is time to transmit beacon information during the transmission of the data information. When the transmission timing is not reached, only the data information is transmitted, and when the transmission timing is reached, the data information is transmitted with beacon information added. On the other hand, when receiving the beacon information from the wireless master station, the wireless slave station switches the communication frequency according to the hopping pattern. Further, when data information is received from the wireless master station, it is determined whether or not beacon information is added to the data information. Then, when added, the communication frequency is switched according to the hopping pattern.

Further, the wireless communication system of the present invention provides a wireless master station with a timer for repeatedly counting a frequency switching cycle of a hopping pattern, and a switching timing of a hopping pattern when detecting that the timer has timed out when data information is not transmitted. Beacon information transmission means for transmitting beacon information to the wireless slave station for synchronizing the data, and when there is data information to be sent to the wireless slave station, the transmission time of the data information is compared with the remaining time until the timer times out. Time comparing means, a first data information transmitting means for transmitting only data information when the data comparing time confirms that the data transmission time is shorter than a remaining time until timeout, and a data transmitting time out by the time comparing means. Confirm that it is longer than the remaining time until the beacon information in the data information Addition to providing the second data information transmitting means for transmitting. Also, when receiving information wirelessly transmitted from the wireless master station, the wireless slave station analyzes whether the received information is beacon information or data information. When it is confirmed that the received information is data information by the first frequency switching control means for switching the communication frequency according to the hopping pattern and by the received information analyzing means, it is determined whether or not beacon information is added to the data information. A beacon presence / absence determining means for performing communication and a second frequency switching control means for switching a communication frequency according to a hopping pattern when the beacon information is determined to be added by the beacon presence / absence determination means.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In this embodiment, FIG.
The case where the present invention is applied to the wireless communication system shown in FIG.

First, each wireless station (the wireless master stations 2a and 2b)
And the wireless slave stations 4a, 4b, 4c, 4d) have a common hardware configuration, and the main part thereof is shown in the block diagram of FIG. As shown, each wireless station has a CPU (Central Pr
main control unit 11 mainly composed of an Ocessing Unit), a storage unit 12 for storing a hopping pattern HP and the like, a beacon timer 13 for repeatedly counting the frequency switching cycle of the hopping pattern HP, and a device (wireless master station 2a, 2
In the case of b, the host device 1 and the wireless slave stations 4a, 4b, 4c,
In the case of 4d, a communication control unit 14 for controlling data communication with the data processing terminal 3), a wireless unit 15 for controlling wireless communication by the FH system, and a serial I / O port 16 for exchanging wireless transmission / reception information with the wireless unit 15 Etc. are provided.

The radio unit 15 modulates transmission information input through the serial I / O port 16 at a modulation frequency and transmits the modulated information through an antenna 17, and an antenna 17.
Demodulates the received information received at the demodulation frequency at the serial I
Receiving unit 19 for sending to the I / O port 16 and the transmitting unit 1
8, a modulation frequency conversion unit 20 that matches the current communication frequency of the hopping pattern HP, and a demodulation frequency in the receiving unit 19 that sets the demodulation frequency to the hopping pattern HP.
And a demodulation frequency conversion unit 20 adapted to the current communication frequency.

In each radio station having such a configuration, the main control unit 11 determines a communication frequency, controls the modulation frequency conversion unit 20 and the demodulation frequency conversion unit 21, and modulates and modulates transmission information at the determined communication frequency. Demodulate received information. Here, the main control unit 11 changes the communication frequency in a time-division manner at a constant cycle according to the hopping pattern HP stored in the storage unit 12.

When performing radio transmission, the main control unit 11 checks whether a radio wave is transmitted in the communication frequency band to be transmitted by the reception unit 19 before transmitting the radio wave (carrier sense). ). If the radio wave is not transmitted in the communication frequency band, the transmission unit 18 modulates the transmission information and transmits the modulated information as the radio wave of the communication frequency. On the other hand, when the radio wave is transmitted in the communication frequency band, the main control unit 11 temporarily suspends the transmission, waits for a predetermined time, and checks again. In addition,
During this time, the communication frequency is changing at a constant cycle.
When rechecking, check at the communication frequency at that time.
Then, when it is confirmed that no radio wave is transmitted in the communication frequency band, the transmission unit 18 modulates the transmission information and transmits it as a radio wave.

By the way, in all the radio stations forming one radio zone, the communication frequency determined by the hopping pattern HP always changes synchronously, and radio communication cannot be performed unless the same frequency band is always used.
Therefore, in the present embodiment, in order to synchronize the communication frequency switching timing, each wireless master station 2a, 2b generates beacon information for synchronizing the hopping pattern switching timing every time the beacon timer 13 times out. And each wireless slave station 4 in the same wireless zone Z1, Z2.
a, 4b, 4c, and 4d are simultaneously broadcast and the communication frequency is switched to the next frequency according to the hopping pattern HP. On the other hand, each of the wireless slave stations 4a, 4b, 4c,
4d, upon receiving the beacon information, switches the communication frequency to the next frequency according to the same hopping pattern HP based on the beacon information. Note that the wireless slave stations 4a, 4
If the beacon information has failed to be received in b, 4c, and 4d, the communication frequency is similarly changed due to the timeout of the own beacon timer 13. By such a method, the wireless master stations 2a and 2b and the wireless slave stations 4a and 4
b, 4c, and 4d always change the communication frequency in synchronization with each other.

In this embodiment, the transmission master stations 2a, 2a
In step b, if there is data information to be transmitted to each of the wireless stations 4a, 4b, 4c, and 4d, it is determined whether or not it is time to transmit beacon information during the transmission of the data information. If the transmission timing does not come, only the data information is transmitted. On the other hand, when the transmission timing of the beacon information comes during the transmission of the data information, the beacon information is added to the data information and transmitted as one wireless transmission frame. At this time, no beacon information is transmitted after the transmission of the wireless transmission frame.

On the other hand, each of the wireless slave stations 4a, 4b, 4c, 4d
Receives data information from the wireless base stations 2a and 2b,
It is determined whether or not beacon information is added to the data information. If it is added, after receiving the data information, it switches its own communication frequency to the next frequency according to the hopping pattern HP.

That is, the wireless master stations 2a and 2b are configured so that the main controller 11 executes the transmission processing shown in the flowchart of FIG. First, as ST (step) 1, it is determined whether or not the beacon timer 13 has timed out.
It is determined whether there is transmission data. When the timeout of the beacon timer 13 is detected in a state where there is no transmission data, a wireless transmission frame of the beacon information is generated as ST3, and the wireless transmission frame of the beacon information is transmitted to the same wireless unit via the wireless unit 15 as ST4. Each of the wireless slave stations 4a, 4b, 4c, 4d in the zones Z1, Z2
Wirelessly (beacon information transmitting means). Also in this case, it is checked whether radio waves are transmitted in the current communication frequency band, and after confirming that radio waves are not transmitted, transmission is performed. After that, the communication frequency is stored in the storage unit 1 as ST5.
The frequency is switched to the next frequency according to the hopping pattern HP set to 2.

On the other hand, if transmission data is generated while the beacon timer 13 has not timed out, ST
As 6, the transmission time A of the data is calculated from the length of the data information to be transmitted and the data transmission speed. Also,
In step ST7, the remaining time B until the timeout occurs is calculated from the current count value of the beacon timer 13. Thereafter, as ST8, the data transmission time A is compared with the remaining time B (time comparison means). As a result, if the data transmission time A is shorter than the remaining time B, the beacon timer 13 does not time out during the transmission of the data information, so that a wireless transmission frame of the transmission data is generated in ST9 and this transmission data is generated in ST10. Wirelessly transmitted to the respective wireless slave stations 4a, 4b, 4c, 4d in the same wireless zone Z1, Z2 via the wireless unit 15 (first wireless transmission frame).
Data information transmission means).

On the other hand, if the data transmission time A is longer than or equal to the remaining time B, the beacon timer 13 times out during the transmission of the data information.
As 11, a wireless transmission frame is generated by adding beacon information to transmission data. Then, similarly to ST4, a wireless transmission frame of the transmission data and the beacon information is wirelessly transmitted to each of the wireless stations 4a, 4b, 4c, and 4d in the same wireless zone Z1 and Z2 via the wireless unit 15 (second example). Data information transmission means). After the transmission, the communication frequency is switched to the next frequency according to the hopping pattern HP as in ST5.

As shown in FIG. 4, the radio transmission frame generally includes a control unit 41 in which information for specifying the type of the frame is set, and an address in which communication address information of the transmission destination and the transmission source of the frame is set. Part 42
And a data section 43 in which transmission data information and beacon information are set. Therefore, the control unit 4
The information set to 1 distinguishes whether the wireless transmission frame is a frame of beacon information, a frame of data information, or a frame in which beacon information is added to data information.

Further, each of the wireless slave stations 4a, 4b, 4c, 4d
Is configured so that the main control unit 11 executes the receiving process shown in the flowchart of FIG. That is, it waits for receiving a wireless transmission frame as ST1. When the wireless transmission frame is received, first, in ST2, the information set in the control unit 41 is analyzed to determine whether a wireless transmission frame including only beacon information has been received (reception information analysis means). Here, when a wireless transmission frame including only beacon information is received, the communication frequency is set according to the hopping pattern HP set in the storage unit 12 based on the beacon information set in the data unit 43 in the frame as ST3. Switching to frequency (1st
Frequency switching control means).

On the other hand, if a wireless transmission frame including data information is received instead of a wireless transmission frame containing only beacon information, a step ST4 determines whether a wireless transmission frame in which beacon information is added to the data information is received. Is determined (beacon presence / absence determination means). If a wireless transmission frame containing only data information is received, ST
As 5, reception processing such as transmitting data information set in the data section 43 in the frame to the data processing terminal 3 connected by wire is performed.

When a wireless transmission frame in which beacon information is added to data information is received, a data information reception process is performed in the same manner as ST5 in ST6.
Similarly to 3, the communication frequency is switched to the next frequency in accordance with the hopping pattern HP (second frequency switching control means).

FIG. 5 shows a wireless master station 2 according to this embodiment.
The example of information transmission timing of a and 2b is shown. In the figure,
Symbol B of the transmission frame indicates a transmission frame of beacon information, D indicates a transmission frame of data information, and DB indicates a transmission frame of information obtained by adding beacon information to data information. That is, each time the beacon timer 13 that repeats the measurement of the fixed time T times out (TO), the wireless master stations 2a and 2b wirelessly transmit the transmission frame B of the beacon information [time points t1 and t8]. If the transmission time of the data information transmission frame is shorter than the remaining time of the beacon timer 13 and the beacon timer 13 does not time out during the transmission of the data information transmission frame, the transmission frame D including only the data information is wirelessly transmitted [time point]. t
2, t3, t6, t7]. On the other hand, the transmission time of the transmission frame of the data information is longer than the remaining time of the beacon timer 13, and the beacon timer 1
When the time-out occurs, the transmission frame DB in which the beacon information is added to the data information is wirelessly transmitted [time t4].

As a result, the wireless master stations 2a and 2b transmit the wireless transmission frame B including only the beacon information at times t1 and t8, and perform the transmission processing of the wireless transmission frame DB in which the beacon information is added to the data information. , The communication frequency is sequentially switched to the next frequency according to the hopping pattern HP. Further, each of the wireless slave stations 4a, 4b, 4c, 4d
Also, the communication frequency is sequentially switched to the next frequency according to the same hopping pattern HP after receiving the wireless transmission frame B including only the beacon information and receiving processing of the wireless transmission frame DB in which the beacon information is added to the data information. Therefore, the same wireless zone Z1, Z2
Wireless master stations 2a and 2b and wireless slave stations 4a and 4
The switching timings of the hopping patterns are synchronized with b, 4c, and 4d.

As described above, according to the present embodiment, the beacon information that has been wirelessly transmitted from the wireless master stations 2a and 2b without fail every time the beacon timer 13 times out is replaced by the beacon timer 13 during data information transmission. In this case, transmission is not performed, so that the time loss of transmitting and receiving data information can be reduced by the transmission time of the beacon information. Therefore, the communication efficiency of the data information can be improved accordingly.

[0031]

As described above in detail, according to the present invention, the beacon information for synchronizing the switching timing of the hopping pattern is not transmitted when the transmission timing of the beacon information comes during the transmission of the data information. Therefore, the time loss of transmitting and receiving the data information can be reduced by the omitted transmission time of the beacon information, and the communication efficiency of the data information can be improved accordingly.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main part of a hardware configuration of a wireless station according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a main part of a transmission process executed by a main control unit of the wireless master station in the embodiment.

FIG. 3 is a flowchart showing a main part of a reception process executed by a main control unit of the wireless slave station in the embodiment.

FIG. 4 is a diagram showing a format of a wireless transmission frame used in the embodiment.

FIG. 5 is a diagram showing an example of information transmission timing of the wireless master station in the embodiment.

FIG. 6 is an overall view of a wireless communication system.

FIG. 7 is a diagram showing an example of a conventional information transmission timing of a wireless master station.

[Explanation of symbols]

 2a, 2b: Wireless master station 4a, 4b, 4c, 4d: Wireless slave station 11: Main control unit 12: Storage unit 13: Beacon timer 14: Communication control unit 15: Wireless unit

Claims (2)

[Claims] 1. 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 communicate with each other in the wireless zone according to a predetermined hopping pattern. A wireless communication method for a wireless communication system in which a wireless communication is performed by changing a frequency in a time-division manner, wherein the wireless master station transmits beacon information to the wireless slave station at a fixed cycle, thereby enabling the wireless master station to communicate with the wireless slave station. In a configuration in which a hopping pattern is synchronized with a station, the wireless master station, if there is data information to be transmitted to the wireless slave station, determines whether or not the transmission timing of the beacon information is transmitted during transmission of the data information. If the transmission timing is not reached, only the data information is transmitted.If the transmission timing is reached, the beacon information is added to the data information and transmitted. When the beacon information is received from the wireless master station, the communication frequency is switched according to the hopping pattern.When the data information is received from the wireless master station, it is determined whether the beacon information is added to the data information. Wherein the communication frequency is switched according to the hopping pattern when added. 2. A wireless zone is formed by one wireless master station and one or more wireless slave stations, and the wireless master station communicates with the wireless slave stations in the wireless zone according to a predetermined hopping pattern. In a wireless communication system that performs wireless communication by changing the frequency in a time-division manner, the wireless master station is a timer that repeatedly counts a frequency switching cycle of the hopping pattern, and that the timer times out when data information is not transmitted. Beacon information transmitting means for transmitting beacon information to the wireless slave station for synchronizing the switching timing of the hopping pattern upon detection, and when there is data information to be transmitted to the wireless slave station, the transmission time of the data information and Time comparing means for comparing the remaining time until the timer times out,
When it is confirmed by the time comparing means that the data transmission time is shorter than the remaining time until the timeout, the first data information transmitting means for transmitting only the data information, and the remaining time until the data transmission time is expired by the time comparing means. A second data information transmitting unit that adds the beacon information to the data information and transmits the data information when confirming that the data is longer, and the wireless slave station receives information wirelessly transmitted from the wireless master station. Receiving information analyzing means for analyzing whether the received information is the beacon information or the data information, and switching the communication frequency according to the hopping pattern when the received information analyzing means confirms that the received information is the beacon information. 1 the frequency information switching control means and the received information analyzing means When it is confirmed that the beacon information is added to the data information, the beacon presence determining means, and when the beacon information is determined to be added by the beacon presence determination means, the communication frequency according to the hopping pattern A wireless communication system comprising: a second frequency switching control unit for switching.