JP2005252353A - Radio communications device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communications device which eliminates the need for an A/D converter etc. on the receiver side. <P>SOLUTION: This radio communication device 1 is provided with an antenna 2, a receiver 4 for receiving a radio wave via the antenna 2, a transmitter 5 for transmitting radio waves via the antenna 2, a changeover switch 3 for switching between the receiver section 4 or the transmitting section 5 and the antenna 2 to connect the section 4 or 5 to the antenna 2, and a transmission/reception control unit 6 for controlling the receiver 4 and the transmitter 5. The unit 6 causes the receiver 4 to operate and receive a frame, calculates bit error rate, if synchronization could not be taken by a preamble, and causes the transmitter 5 to operate to transmit the data, if the bit error rate is not smaller than a predetermined threshold. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a wireless communication apparatus.

  Generally, in an emergency transmission wireless communication system that does not use a base station, a data transmission side device (hereinafter referred to as “transmission side device”) can receive data from a data reception side device (hereinafter referred to as “reception side device”). After confirming that it is in a state, data is transmitted.

As described above, when confirming that the receiving device is in a data receivable state, the transmitting device and the receiving device perform the following operations.
(1) First, the transmission side apparatus transmits a signal for confirming the state of the reception side apparatus.
(2) Next, the receiving side apparatus receives the signal transmitted by the transmitting side apparatus, and prepares for data reception according to the level of the carrier detection signal (RSSI (Received Signal Strength Indication) signal).
(3) Then, the receiving side apparatus transmits a signal indicating that preparation for data reception is completed.
(4) The transmission side apparatus can confirm that the reception side apparatus is in a data receivable state by receiving a signal indicating that preparation for data reception is completed, and then transmits the data. .

However, when it is confirmed that the receiving side apparatus is in a data receivable state as described above, an A / D converter or an analog comparator for determining the level of the carrier detection signal (RSSI signal) is included in the receiving side apparatus. This is necessary and causes an increase in power consumption, chip size, and cost. Furthermore, since it takes time to A / D-convert or analog-compare the carrier detection signal (RSSI signal), the communication response speed is reduced.
Further, in an emergency transmission wireless communication system using weak radio waves, it may be difficult to determine whether the carrier detection signal (RSSI signal) is a carrier or noise because the carrier detection signal (RSSI signal) is not linear in the vicinity of the sensitivity point. It was.

  Incidentally, an emergency transmission intermittent reception wireless communication method is known as means for reducing power consumption in a wireless communication system (see, for example, Patent Document 1).

  However, the emergency transmission intermittent reception wireless communication method disclosed in Patent Document 1 is an intermittent operation in which a first receiving station in a wireless communication system is in a state capable of receiving at a first predetermined period for a first predetermined period. A step of transmitting a first activation signal for activating the first receiving station from a transmitting station for a second predetermined period longer than a first predetermined period, and a first in an intermittent operation state Including a step of detecting a first activation signal at a first receiving station in a predetermined period, and a step of switching the first receiving station from an intermittent operation state to a constant operation upon detection of the first activation signal. Therefore, when the reception operation is unnecessary, the power consumption is reduced by turning off the power of the reception unit, and an A / D converter or an analog comparator for judging the level of the carrier detection signal (RSSI signal) Unnecessary Not shall.

JP 2003-87180 A

  Therefore, in view of the above points, the present invention provides wireless communication that does not require an A / D converter or an analog comparator for determining the level of a carrier detection signal (RSSI (Received Signal Strength Indication) signal) in a receiving side device. An object is to provide an apparatus.

  In order to solve the above problems, a wireless communication device according to the present invention is a device for performing wireless communication, in which a frame is received and synchronization is not achieved by a preamble added to the head of the frame The bit error rate of the preamble is calculated, and transmission data is transmitted when the bit error rate is equal to or higher than a predetermined threshold.

  In this wireless communication apparatus, an antenna, a receiving unit for receiving radio waves via the antenna, a transmitting unit for transmitting radio waves via the antenna, and switching between the receiving unit or the transmitting unit and the antenna are switched. A selector switch for connection and a transmission / reception control unit for controlling the reception unit and the transmission unit. The transmission / reception control unit operates the reception unit to receive the frame, and is added to the head of the frame. It is also possible to calculate the bit error rate of the preamble when synchronization is not achieved by the preamble being used, and when the bit error rate is greater than or equal to a predetermined threshold, operate the transmitter to convert the transmission data into radio waves and transmit .

  Further, the transmission / reception control unit may operate the receiving unit to receive the frame, and receive the received data when synchronization is achieved by the preamble added to the head of the frame.

  The transmission / reception control unit may include a parameter recording unit that records a predetermined threshold, or the predetermined threshold recorded in the parameter recording unit may be rewritable from the outside.

The best mode for carrying out the present invention will be described below with reference to the drawings. In addition, the same referential mark is attached | subjected to the same component and description is abbreviate | omitted.
FIG. 1 is a diagram illustrating a system using a wireless communication apparatus according to an embodiment of the present invention. As shown in FIG. 1, this system includes wireless communication devices 1, 10, and 11.

The wireless communication device 1 includes an antenna 2, a changeover switch 3, a reception unit 4, a transmission unit 5, and a transmission / reception control unit 6. The transmission / reception control unit 6 includes a CPU core 7, a parameter recording unit 8, and a transmission / reception buffer 9.
The receiving unit 4 operates under the control of the transmission / reception control unit 6, receives a radio wave from the wireless communication device 10 or 11 via the antenna 2, converts the received radio wave into a signal, and outputs the signal to the transmission / reception control unit 6. To do.

The transmission unit 5 operates under the control of the transmission / reception control unit 6 and transmits transmission data to the wireless communication device 10 or 11 via the antenna 2.
The changeover switch 3 switches between the receiving unit 4 and the antenna 2 or between the transmitting unit 5 and the antenna 2 for connection.

The transmission / reception control unit 6 includes a CPU core 7, a parameter recording unit 8, and a transmission / reception buffer 9.
At the time of data transmission, transmission data is written in the transmission / reception buffer 9, and the CPU core 7 controls the transmission unit 5 and the reception unit 4 by executing firmware, and wirelessly transmits the transmission data written in the transmission / reception buffer 9. It transmits to the communication apparatus 10 or 11. At the time of data reception, the CPU core 7 controls the reception unit 4 by executing the firmware, and writes the reception data in the transmission / reception buffer 9. The reception data written in the transmission / reception buffer 9 is output to an external circuit.
The parameter recording unit 8 includes an EEPROM, a RAM, and the like, and records a predetermined threshold (for example, 90%) as will be described in detail later. This threshold value may be rewritable by an external circuit. Further, the parameter recording unit 8 may be configured by a mask ROM or the like.

  In the present embodiment, the internal configuration of the wireless communication devices 10 and 11 is the same as that of the wireless communication device 1.

FIG. 2 is a flowchart showing an outline of the operation of the wireless communication device 1. Hereinafter, the operation of the wireless communication apparatus 1 will be described in more detail with reference to FIGS. 1 and 2.
The wireless communication device 1 repeatedly executes the process shown in FIG. 2 at predetermined time intervals.

When the processing shown in FIG. 2 is started, the CPU core 7 in the transmission / reception control unit 6 turns on the reception unit 4 (step S1). Thereby, the receiving part 4 starts reception of an electromagnetic wave.
Next, the CPU core 7 receives a frame from the receiving unit 4 and acquires a preamble added to the head of this frame (step S2).

  Then, the CPU core 7 checks whether or not synchronization has been achieved by the preamble. If synchronization has not been achieved, the process proceeds to step S4. If synchronization has been achieved, the process proceeds to step S12 (step S3). ). For example, if the CPU core 7 can recognize that the preamble is “0xAA (0b10101010)” or “0x55 (0b01010101)”, the CPU core 7 determines that synchronization has been achieved; otherwise, it indicates that synchronization has not been achieved. It may be judged.

If it is determined in step S3 that synchronization has not been achieved, the CPU core 7 calculates a bit error rate (BER) of the preamble (step S4). In general, the bit error rate can be calculated by dividing the number of error bits by the number of transmission bits.
Next, the CPU core 7 checks whether or not there is transmission data in the transmission / reception buffer 9 (step S5). If there is no transmission data, the CPU 4 turns off the reception unit 4 (step S11) and ends the processing. To do.

  When there is transmission data addressed to the wireless communication device 10 or 11, the CPU core 7 uses the threshold (90% in this embodiment) in which the bit error rate calculated in step S4 is recorded in the parameter recording unit 8. It is checked whether or not it is above (step S6). FIG. 3 is a diagram illustrating an example of a graph representing a relationship between radio wave reception sensitivity and a bit error rate. As shown in FIG. 3, when the radio wave reception sensitivity is high, the preamble bit error rate is low, and when the radio wave reception sensitivity is low, the preamble bit error rate is high. In FIG. 3, when the bit error rate is 90% or more (for example, range A in FIG. 3), a frequency band that is the same as or close to the frequency band used by the wireless communication device 1 is used in the vicinity of the wireless communication device 1. In other words, in this embodiment, the wireless communication device 10 and the wireless communication device 11 are not performing wireless communication. Therefore, if the bit error rate calculated in step S4 is equal to or greater than the threshold value recorded in the parameter recording unit 8, the CPU core 7 turns on the transmission unit 5 (step S7) and sets the transmission / reception buffer 9 in the transmission / reception buffer 9. The written transmission data is converted into radio waves and transmitted to the wireless communication device 10 or 11 (step S8), and then the receiving unit 4 and the transmitting unit 5 are turned off (step S9), and the process is terminated.

  On the other hand, in FIG. 3, when the bit error rate is about 1% (for example, range B in FIG. 3), a frequency band that is the same as or close to the frequency band used by the wireless communication apparatus 1 is used in the vicinity of the wireless communication apparatus 1. There is a device in use, that is, in this embodiment, the wireless communication device 10 and the wireless communication device 11 are performing wireless communication. Therefore, if the bit error rate calculated in step S4 is not equal to or greater than the threshold value recorded in the parameter recording unit 8, the CPU core 7 waits for a predetermined time (step S10) and returns the process to step S1. Thereby, the radio | wireless communication apparatus 1 can retry transmission after predetermined time, when the radio | wireless communication apparatus 10 and the radio | wireless communication apparatus 11 are communicating.

  By the way, when synchronization is obtained in step S3, that is, when the wireless communication device 10 or 11 is transmitting radio waves to the wireless communication device 1, the CPU core 7 receives data from the wireless communication device 10 or 11. In step S12, the receiving unit 4 is turned off (step S13), and the received data recorded in the transmission / reception buffer 9 is output to an external circuit (step S14). Thereafter, the CPU core 7 checks whether or not there is transmission data in the transmission / reception buffer 9. If there is transmission data, the process returns to step S1, and if there is no transmission data, the process ends. (Step S15).

  As described above, the wireless communication device 1 can perform data transmission when synchronization by the preamble is not achieved and the bit error rate (BER) of the preamble is equal to or greater than a predetermined threshold. Therefore, the A / D conversion for determining the level of the carrier detection signal (RSSI (Received Signal Strength Indication) signal) in the receiving side device (in this embodiment, the wireless communication devices 1, 10, and / or 11). Or an analog comparator can be dispensed with. Thereby, low power consumption, space saving, and cost reduction can be realized. In addition, time for A / D conversion or analog comparison of the carrier detection signal (RSSI signal) is not required, and the operation time can be shortened, and the power consumption during operation can be reduced by shortening the operation time. .

  The present invention can be used in a wireless communication apparatus. Furthermore, the present invention can be used in a wireless communication module or the like for incorporation in various devices.

The figure which shows the system using the radio | wireless communication apparatus which concerns on one Embodiment of this invention. 3 is a flowchart showing the operation of the wireless communication device 1 of FIG. The figure which shows an example of the relationship between the radio wave reception sensitivity and the bit error rate.

Explanation of symbols

  1, 10, 11 Wireless communication device, 2 antenna, 3 changeover switch, 4 receiving unit, 5 transmitting unit, 6 transmission / reception control unit, 7 CPU core, 8 parameter recording unit, 9 transmission / reception buffer

Claims (5)

An apparatus for performing wireless communication,
Receives a frame, calculates the bit error rate of the preamble when synchronization is not achieved by the preamble added to the head of the frame, and transmits transmission data when the bit error rate is equal to or greater than a predetermined threshold A wireless communication device. An antenna,
A receiver for receiving radio waves via the antenna;
A transmitter for transmitting radio waves via the antenna;
A changeover switch for switching and connecting between the receiving unit or the transmitting unit and the antenna;
A transmission / reception control unit for controlling the reception unit and the transmission unit,
The transmission / reception control unit
The reception unit is operated to receive a frame, and when the synchronization is not achieved by the preamble added to the head of the frame, the bit error rate of the preamble is calculated, and the bit error rate is equal to or higher than a predetermined threshold 2. The wireless communication apparatus according to claim 1, wherein the transmission unit is operated to convert the transmission data into a radio wave and transmit it. The transmission / reception control unit
3. The wireless communication apparatus according to claim 2, wherein the reception unit is operated to receive a frame, and reception data is received when synchronization is established by a preamble added to a head portion of the frame. 4. The wireless communication apparatus according to claim 2, wherein the transmission / reception control unit includes a parameter recording unit that records the predetermined threshold. The wireless communication apparatus according to claim 4, wherein the predetermined threshold value recorded in the parameter recording unit is rewritable from the outside.

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