JP4795057B2 - Receiver - Google Patents

Description

  The present invention relates to a receiver provided in a mobile station in a digital radio system for fire fighting and emergency, for example.

  In recent years, digitization has progressed in many wireless systems such as regional disaster prevention wireless systems and commercial wireless systems such as trains and taxis. At present, the radio system for fire fighting / emergency is being digitized by adopting the TDMA (Time Division Multiple Access) method and the SCPC (Single Channel Per Carrier) method.

  In addition, in the radio system for fire fighting / emergency, even if the mobile station exists in a multipath environment such as a building shadow, the base station radio and mobile stations that make up the radio system can provide stable communication quality. An equalization processing means for reducing the influence of fading or the like in the propagation path is incorporated in the receiving device of the station radio (see, for example, Patent Document 1).

JP 2000-68710 A

  However, it is also well known that the reception performance in a weak electric field deteriorates when this equalization processing is performed. For example, in a place where the reception strength is low, away from the base station, the reception electric field strength may further decrease due to the equalization process, and communication may not be possible. Since a fire fighting / emergency radio system requires urgency, it is desirable to ensure a wide communication area.

  The present invention has been made paying attention to the above circumstances, and an object of the present invention is to provide a receiving apparatus capable of ensuring a wide communication area and improving communication quality.

  In order to achieve the above object, a receiving apparatus according to the present invention comprises a receiving means for receiving a radio signal arriving via a radio line, a detecting means for detecting a received electric field intensity from the received radio signal, and the receiving Equalization processing means for performing waveform equalization processing of the received radio signal, and comparing the detected received electric field strength with a threshold value to determine whether or not the detected received electric field strength is smaller than the threshold value for a certain time or more If the determination means and the determination means determine that the detected received electric field strength is greater than a threshold value, the equalization processing means is operated, and the received electric field strength detected by the determination means is a predetermined time. Control means for stopping the equalization processing means when determined to be smaller than the threshold value as described above.

  In the above configuration, a means for switching whether or not to perform the equalization process is provided, the equalization process is performed when the received electric field strength is equal to or greater than the threshold value, and the equalization process is performed when the received electric field strength is lower than the threshold value. Do not run. By configuring in this way, it is possible to ensure good communication quality even in an area having a lower electric field strength than in the case where equalization processing is always performed.

  A vehicle-mounted receiving device according to the present invention includes a vehicle-mounted first receiver and a portable second receiver that is detachably attached to the first receiver. A first receiver that receives a wireless signal that arrives via a wireless line; and a first detector that detects a received electric field strength from the received wireless signal. A first determination means for comparing the detected received electric field strength with a threshold value and determining whether the detected received electric field strength is smaller than the threshold value for a certain time or more, and according to a first time response characteristic. A first equalization processing means for performing a waveform equalization process; and if the received electric field strength detected by the determination means is determined to be greater than a threshold, operate the first equalization processing means, The received electric field strength detected by the determining means is And a first control means for said first equalization means is stopped when it is determined to be smaller than the constant time or more thresholds. In addition, the second receiver includes a second receiving unit that receives a radio signal arriving via the radio line, a second detecting unit that detects a received electric field strength from the received radio signal, A second determination means for comparing the detected received electric field strength with a threshold and determining whether the detected received electric field strength is smaller than the threshold; and a second time later than the first time response characteristic Second equalization processing means for performing waveform equalization processing according to response characteristics; and when the determination means determines that the detected received electric field strength is greater than a threshold value, the second equalization processing means And a second control unit that is operated and stops the second equalization processing unit when the determination unit determines that the detected received electric field strength is smaller than a threshold value.

  In the above configuration, the equalization processing is stopped when a decrease in the received electric field strength is detected for a certain time or more with respect to the equalizer for high-speed fading. On the other hand, in the case of an equalizer for low-speed fading, the equalization process is stopped as soon as a decrease in received electric field strength is detected. Thus, by controlling the equalization process according to the time response characteristic of the equalizer, it is possible to always maintain better communication quality.

  Therefore, according to the present invention, it is possible to provide a receiving apparatus that can ensure a wide communication area and improve communication quality.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic view showing an embodiment of a fire fighting / emergency radio system.
A base station zone 101 indicates a radio area of the radio base station 102. A remote controller 104 provided in the fire department corps headquarters 103 is connected to the radio base station 102 and controls the base station radio. The mobile stations 105, 106, and 107 are in-vehicle wireless devices and portable wireless devices mounted on fire engines and ambulances. The remote controller 104 can perform simultaneous communication and individual communication to the mobile stations 105, 106, and 107 in the base station zone 101 via the wireless base station 102. The mobile stations 105, 106, and 107 can perform communication with the remote controller 104 (base station communication) and communication with other mobile stations (communication between mobile stations) via the radio base station 102. In addition, mobile stations can perform communication (direct communication between mobile stations) using a dedicated frequency band without going through the radio base station 102.

  In this way, at least one remote controller 104 or radio base station 102 as described above is arranged in the fire fighting / emergency radio system. Each radio base station 102 is also connected to the security headquarters 109 and the direction headquarters 111 via the radio network controller 108. From the disaster emergency control stand 110 of the security headquarters 109 and the remote controller 112 of the direction headquarters, each base station Simultaneous communication and individual communication can be performed for mobile stations in the zone.

FIG. 2 is a block diagram illustrating an example of a configuration of a wireless terminal provided in the mobile stations 105, 106, and 107 illustrated in FIG.
The wireless terminal includes an in-vehicle wireless device 201, a portable wireless device 202, a table 203, antennas 204 and 205, speakers 206 and 207, handsets 208 and 209, and an operation display 210.

  This wireless terminal is configured as a one-station / two-device device that includes a vehicle-mounted wireless device 201 and a portable wireless device 202. When the portable wireless device 202 is placed on a table 203, the vehicle-mounted wireless device 201 is When the mobile station 202 is a wireless station and the mobile wireless device 202 is not placed on the table 203, the mobile wireless device 202 is a wireless station. When the portable wireless device 202 is a wireless station, the in-vehicle wireless device 201 cannot perform transmission but can only perform reception. While moving in a vehicle, the portable wireless device 202 is placed on the table 203, and the in-vehicle wireless device 201 becomes a wireless station, but when working outside the vehicle, the portable wireless device 202 is taken out of the table 203, The same radio station can be used even during activities outside the vehicle.

  In addition, two antennas 204 and 205 and two speakers 206 and 207 are connected to the in-vehicle wireless device 201. A plurality of handsets 208 and 209 can be connected. In the fire fighting / emergency radio system, all communications are highly important. By doing so, communication from the radio base station 102 (base station communication) and communication using dedicated waves from mobile stations (directly between mobile stations) Communication) can be received and monitored simultaneously. Also, an operation indicator 210 for displaying data communication operations and received data is connected to the in-vehicle wireless device 201. Furthermore, a personal computer 211 and an electrocardiogram measuring device 212 can be connected, and measurement data such as an electrocardiogram and various information can be captured by data communication.

Next, the configuration of the in-vehicle wireless device 201 and the portable wireless device 202 will be described.
First, the in-vehicle wireless device 201 will be described with reference to FIG. When transmitting the in-vehicle wireless device 201, the control unit 301 transmits transmission data such as audio data and data for data communication from the audio codec to the transmission frame processing unit 302. The transmission frame processing unit assembles signals in accordance with a signal format defined by a standard or the like, such as error correction coding of received transmission data. The signal assembled in the transmission frame processing unit 302 is subjected to modulation processing such as π / 4 shift QPSK (Quadri-Phase Shift Keying) in the modulation unit 303, and the modulated signal is sent to the transmission high-frequency unit 304. During transmission, the antenna switch 305 is connected to the transmission high-frequency unit 304, and the modulated wave converted to a radio frequency by the transmission high-frequency unit 304 is output via the antenna 306.

  On the other hand, at the time of reception, the antenna switch 305 is connected to the reception high frequency unit 307, and a signal received by the antenna 306 is sent to the reception high frequency unit 307. The reception high frequency unit 307 converts the received signal into a low frequency that can be processed by the demodulation processing unit 308. The converted signal is demodulated and decoded by the demodulation processing unit 308.

  The demodulation processing unit 308 is configured by a DSP (Digital Signal Processor) or the like. Further, by incorporating equalization processing in the demodulation processing unit 308, the influence of delayed waves and fading generated in a multipath environment is reduced. In particular, this equalization process compensates for high-speed fading due to the moving speed of the vehicle. The equalization processing determination unit 310 controls execution / stop of the equalization processing of the demodulation processing unit 308 based on the received electric field strength detected from the reception signal by the demodulation processing unit 308.

  The decoded data is subjected to error correction and the like in the reception frame processing unit 309 and then decomposed according to the signal format and sent to the control unit 301. The control unit 301 outputs the received data to an audio codec, an information terminal, or the like according to the received data information.

  The in-vehicle wireless device 201 is provided with a portable wireless device I / F 311, detects whether the portable wireless device 202 is placed on the table 203, and indicates the attachment / detachment status of the portable wireless device 202 to the control unit 301. Send a signal. When the control unit 301 detects from this signal that the portable wireless device 202 has been removed from the table 203, the control unit 301 stops the execution of the transmission process and operates only the reception process.

FIG. 4 is a block diagram showing a configuration of the portable wireless device 202.
The portable wireless device 202 includes a control unit 401, and a microphone 411 and a speaker 412 are connected to the control unit 401. Similarly to the in-vehicle wireless device 201, the transmission frame processing unit 402, the modulation unit 403, the transmission high frequency unit 404, the antenna switch 405, the antenna 406, the reception high frequency unit 407, the demodulation processing unit 408, the reception frame processing unit 409, and the equalization processing A determination unit 410 is provided. Since the procedure of the transmission / reception process in the portable wireless device 202 is the same as that of the in-vehicle wireless device 201, detailed description is omitted.

  The control unit 401 supplies the transmission frame processing unit 402 with the voice data of the site user or the like collected by the microphone 411. The transmission frame processing unit 402 generates a transmission signal from the audio data. The generated transmission signal is modulated by modulation section 403, converted to a radio frequency by transmission high frequency section 404, and then output via antenna 306.

  On the other hand, a radio signal arriving from the base station or another mobile station is received by the antenna 306, frequency-converted by the reception high-frequency unit 407, and then input to the demodulation processing unit 408. The converted signal undergoes demodulation processing in the demodulation processing unit 408 and is decomposed into audio data according to the signal format by the reception frame processing unit 409. Then, under the control of the control unit 401, the sound data is output as sound from the speaker 412.

  The demodulation processing unit 408 has an equalization processing function that compensates for low-speed fading of the received signal. This is because the portable wireless device 202 is carried by a field user. The equalization processing determination unit 410 controls the operation of this equalization processing according to the received electric field strength detected by the demodulation processing unit 408.

Next, an equalization process performed by the wireless terminal configured as described above will be described.
First, the equalization process of the in-vehicle wireless device 201 will be described. FIG. 5 is a flowchart showing the processing procedure and contents of the equalization processing determination unit 310.
In FIG. 5, the equalization processing determination unit 310 acquires a received signal strength indication signal (RSSI: Received Signal Strength Indicator) indicating the received electric field strength of the radio channel detected by the demodulation processing unit 308 (step S5a). Next, it is determined whether or not the received electric field strength represented by the acquired RSSI is smaller than a predetermined threshold value (step S5b). In this determination, when it is determined that the received electric field strength is smaller than the threshold value, it is determined whether or not the timer is operating (step S5c). If the timer is not in operation, after starting the timer (step S5d), the process returns to step S5a to perform the above processing. The timer value is set with a permissible time so that the equalization process is continued without stopping the equalization process for a momentary decrease in received electric field strength.

  If it is determined in step S5c that the timer is operating, it is determined whether or not the timer has ended (step S5e). If the timer has not expired, the process returns to step S5a and the above process is repeated. If the equalization process determination unit 310 determines that the timer has expired in step S5e, the equalization process determination unit 310 sends a control signal to stop the equalization process to the demodulation processing unit 308 (step S5f).

On the other hand, if the equalization processing determination unit 310 determines in step S5b that the received electric field strength is greater than the threshold value, the equalization processing determination unit 310 sends a control signal instructing execution of the equalization processing to the demodulation processing unit 308 (step S5g).
With this configuration, the equalization process is stopped when the received electric field strength falls below the threshold value for a certain time or more, and the equalization process is immediately executed when the received electric field strength returns to the threshold value or more. As a result, it is possible to ensure better communication quality even in an area having a low electric field strength as compared with the case where the equalization process is always performed. Further, since the equalization process is not stopped when the received electric field strength is momentarily reduced, stable communication quality can be ensured.

Next, the equalization process of the portable wireless device 202 will be described. FIG. 6 is a flowchart showing the processing procedure and contents of the equalization processing determination unit 410.
In FIG. 6, the equalization processing determination unit 410 acquires RSSI representing the received electric field strength of the wireless line detected by the demodulation processing unit 408 (step S <b> 6 a). Next, it is determined whether or not the received electric field strength represented by the acquired RSSI is smaller than a predetermined threshold (step S6b). In this determination, when it is determined that the received electric field strength is smaller than the threshold value, the process proceeds to step S6c, and a control signal instructing to stop the equalization process is transmitted to the demodulation processing unit 408. On the other hand, if it is determined in step S6b that the received electric field strength is greater than or equal to the threshold value, the process proceeds to step S6d, and a control signal instructing execution of equalization processing is sent to the demodulation processing unit 408.

In this way, in the case of low-speed fading, since equalization processing is stopped immediately when entering an area where the reception electric field strength is low, it is possible to quickly prevent a decrease in reception level and always maintain good communication quality. Become.
Therefore, according to the above embodiment, the equalization process is executed / stopped based on the detected received electric field strength and the time response characteristic of the waveform equalization process. By doing in this way, compared with the case where the equalization process is always performed, favorable communication quality can be ensured in an area with a lower electric field strength.

  The present invention is not limited to the above embodiment. 5 and 6 described the method for executing / stopping the equalization process based on the received electric field strength. As another method, a position detection unit such as a GPS receiver is provided in the wireless terminal, and the detected terminal position is linked with area information prepared in advance, so that a specific area (for example, an area with weak electric field strength or a multipath environment) It is also possible to switch the execution / stop of equalization processing when entering an area that is likely to become.

  In short, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

Schematic which shows one Embodiment of the fire fighting / emergency radio system of this invention. The block diagram which shows an example of a structure of the radio | wireless terminal provided in the mobile station shown in FIG. The block diagram which shows the structure of the vehicle-mounted radio | wireless machine shown in FIG. The block diagram which shows the structure of the portable radio | wireless machine shown in FIG. The flowchart which shows the procedure and the content of the equalization process control for vehicle-mounted radio | wireless machines shown in FIG. The flowchart which shows the procedure of the equalization process control for the portable radio | wireless machines shown in FIG. 1, and its content.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Base station zone, 102 ... Radio base station, 103 ... Fire department bureau headquarters, 104 ... Remote controller, 105, 106, 107 ... Mobile station, 108 ... Radio network controller, 109 ... Security headquarters, 110 ... Disaster emergency Control table, 111 ... headquarters, 112 ... remote controller, 201 ... in-vehicle radio, 202 ... portable radio, 203 ... table, 204, 205 ... antenna, 206, 207 ... speaker, 208, 209 ... handset, 210 ... Operation indicator 211... Personal computer 212 Electrocardiogram measuring instrument 301 Control unit 302 Transmission frame processing unit 303 Modulation unit 304 High-frequency transmission unit 305 Antenna switch 306 Antenna 307 Reception high-frequency unit, 308... Demodulation processing unit (including equalization processing for high-speed fading), 309... Reception frame processing unit 310 ... Equalization processing determination unit, 311 ... Portable wireless device I / F, 401 ... Control unit, 402 ... Transmission frame processing unit, 403 ... Modulation unit, 404 ... Transmission high frequency unit, 405 ... Antenna switch, 406 ... Antenna, 407 ... reception high frequency section, 408 ... demodulation processing section (including equalization processing for low-speed fading), 409 ... reception frame processing section, 410 ... equalization processing determination section, 411 ... microphone, 412 ... speaker.

Claims (2)

Receiving means for receiving a wireless signal arriving via a wireless line;
Detecting means for detecting received electric field strength from the received radio signal;
Equalization processing means for performing waveform equalization processing of the received radio signal;
Compared with a predetermined threshold the detected received field strength, the detected received signal strength determination means for determining less or not than a predetermined time greater than or equal to the threshold value,
Wherein if the detected received electric field strength is determined to be larger than the threshold value by the determination unit operates the said equalization means, said determining means by the detected received electric field strength is a predetermined time greater than or equal to the threshold value And a control unit that stops the equalization processing unit when it is determined that the value is smaller than the value. A first receiver for in-car use and a second portable for detachable attachment to the first receiver
A vehicle-mounted receiving device comprising:
The first receiver
First receiving means for receiving a wireless signal arriving via a wireless line;
First detection means for detecting a received electric field intensity from the received radio signal;
A first determination unit that compares the detected received electric field strength with a predetermined first threshold value and determines whether the detected received electric field strength is smaller than the first threshold value for a predetermined time or more; ,
First equalization processing means for performing waveform equalization processing according to a first time response characteristic;
When the determination means determines that the detected received electric field strength is greater than the first threshold, the first equalization processing means is operated, and the received electric field strength detected by the determination means And a first control means for stopping the first equalization processing means when it is determined that is less than the first threshold for a certain time or more,
The second receiver is
Second receiving means for receiving a wireless signal arriving via the wireless line;
Second detection means for detecting a received electric field intensity from the received radio signal;
A second determination means for comparing the detected received electric field strength with a predetermined second threshold and determining whether the detected received electric field strength is smaller than the second threshold;
Second equalization processing means for performing waveform equalization processing according to a second time response characteristic slower than the first time response characteristic;
When the determination means determines that the detected received electric field strength is greater than the second threshold value, the second equalization processing means is operated, and the received electric field strength detected by the determination means And a second control unit that stops the second equalization processing unit when it is determined that is smaller than the second threshold value.

Images