WO2010018824A1

WO2010018824A1 - Radio base station device, radio relay device, and digital radio system

Info

Publication number: WO2010018824A1
Application number: PCT/JP2009/064181
Authority: WO
Inventors: 寿彦遠藤; 太一真島
Original assignee: 株式会社ケンウッド
Priority date: 2008-08-11
Filing date: 2009-08-11
Publication date: 2010-02-18

Abstract

It is possible to provide a digital radio system, a radio base station device, and a radio relay device which can receive and demodulate digital data in a frame even if the data is delayed or missing in a terminal device during relay of the data without outputting an uncomfortable sound. The radio base station device (relay device) rebuilds digital data obtained by receiving/demodulating a frame signal again into a frame signal and then retransmits the data. The device includes a frame rebuilding means which sets IDLE data, CRC error data, or FEC error data if the data in the received/demodulated frame cannot be normally acquired. The same principle can be applied to the radio relay device and the digital radio system so as to prevent output of an uncomfortable audio at a mobile communication terminal.

Description

Radio base station apparatus, radio relay apparatus, and digital radio system

The present invention relates to a radio base station apparatus, a radio relay apparatus, and a digital radio system, and in particular, the generation of demodulated audio distortion on the mobile communication terminal side due to missing or delayed frame data when digital radio signals are relayed. The present invention relates to a radio base station apparatus, a radio relay apparatus, and a digital radio system provided with means for preventing.

In digital wireless communication, data to be transmitted is transmitted and received in frame units, but a synchronization word having a specific signal arrangement pattern at a predetermined position of each frame on the transmitter side (frame synchronization word: Frame Sync Word: hereinafter “FSW”) The receiver side establishes synchronization by detecting the synchronization word in the detection output signal. As described above, in digital wireless communication, the frame configuration and symbol timing are configured based on a predetermined communication protocol.

In digital wireless communication, signals to be transmitted such as audio signals and control signals on the transmitting side are transmitted as digital signals superimposed on a carrier wave, and processing on the receiving side is restored to the original audio signals and control signals. However, in order to increase the speed of signal processing, these processes include a DSP (Digital Signal Processor or Processing; digital signal processing device), which is a signal processing unit dedicated to signal processing, in addition to a CPU that controls the whole. I have.
Also, in mobile communication systems, the transmission power on the mobile communication terminal side is reduced for effective use of frequencies and miniaturization of mobile communication terminals, and radio base station devices and radio relay devices are arranged everywhere, Those that are connected by a communication network are the mainstream.

FIG. 7 is a system outline diagram showing an example of a radio base station apparatus used in the digital radio system. As shown in FIG. 7, a radio wave transmitted from a digital radio A that is a mobile communication terminal is received and demodulated by a digital radio base station A that is the nearest radio base station apparatus. At that time, the FSW added to the head of the frame is detected, the subsequent data frame is demodulated, and then the nearest digital radio base station (base station) of the communication partner digital radio (mobile communication terminal) B is transmitted via the network. Station apparatus) B. Based on the received information, the digital radio base station B reconstructs a predetermined frame to which FSW is added, and superimposes it on a radio wave and transmits it to the digital radio B.

The digital radio base station A can also operate as a relay station that transmits a frame reconstructed from the radio wave transmitted by the digital radio A to mobile stations (not shown) around the station.
Each of the digital radio base stations A and B includes at least one controller for the control channel and a plurality of communication channel controllers, and both the digital radio base stations A and B have radio communication means, wired communication means, and optical communication. It is connected by a communication network such as a cable. In many cases, the communication network includes a circuit switch, and is configured so that the nearest digital radio base stations of a target radio communication terminal are connected to each other. ing.

FIG. 8 is a block diagram showing a general outline configuration of the digital radios A and B. As a transmission system, a microphone 21 for converting sound into an electric signal, a microphone amplifier 22, and a codec circuit for digitally encoding the sound signal (CODEC) 23, a press switch or a relay switch 24 for connecting an audio signal to the transmitter, an audio amplifier 25, a modulation level adjuster 26, a voltage controlled oscillator (modulator) 27, and the like. As a receiving system, an intermediate frequency amplifier 31 that converts a high frequency signal received by an antenna into an intermediate frequency signal, an amplifier 32 that amplifies the signal to a required level, an AD converter 33 that converts an analog signal into a digital signal, digital conversion The DSP 34 functions as a vocoder, the sound signal is demodulated from the received signal, the microcomputer 35 that controls the entire apparatus, the sound amplifier 36 that amplifies the sound signal supplied via the codec circuit 23, the sound A level adjuster 37, a speaker 38, and the like are included.

Regarding speech coding in such digital wireless communication, for example, Patent Document 1 discloses a technique related to an inter-channel synchronization method in a digital wireless base station and an inter-channel synchronization program therefor, which can be referred to. .
As a frame configuration in the digital radio system, for example, the one shown in FIG. 9 is known. That is, FIG. 9A shows a configuration example of a voice frame. A synchronization word (FSW) at the head, a link information channel (LICH) indicating frame structure information, and control information are transmitted at a low speed. A slow associated channel (SACCH) is arranged, followed by a voice channel (VCH) for transmitting compressed voice encoded data. FIG. 9B shows a still frame that is configured to transmit control information at high speed instead of speech encoded data during normal speech frame transmission. Similarly, a synchronization word (FSW) is placed at the head. The link information channel (LICH) and the low-speed associated channel (SACCH) are arranged, and the high-speed associated channel (FACCH1) having two data channels as one data structure follows.

Further, IDLE data is used as data applied to an accompanying channel (SACCH and FACCH1) for transmitting control information, which is used when there is no information to be notified, such as a standby operation during transmission. The IDLE data is used by both the mobile station and the base station. Specifically, at the beginning of transmission of the mobile station, for several tens of milliseconds while the voice is processed and converted into data, the base station The data used during the relay operation is switched while the transmission continues (for example, when the voice is interrupted and data communication is started, or when the call channel is activated and multiple radios are talking alternately) is there.
JP 2007-235281 A

However, if data is transmitted through the communication line in this way, data in the frame may be lost due to various reasons such as noise mixing or phase delay. growing. Therefore, as described above, when a radio signal including digitally encoded information is received and demodulated (or received and decoded), and then digitally encoded again and retransmitted, data loss in a frame due to reception decoding or transmission may occur. When a delay occurs, it becomes impossible to reconstruct those frames, and the frames are lost.
FIG. 10 is a diagram for explaining problems associated with frame relay processing in such a conventional radio base station apparatus and radio relay apparatus, and FIG. 10 (a) is a diagram in which digital radio base station B is connected via a network. FIG. 10B shows an example of a frame configuration when re-encoded or re-framed for re-transmission to the digital radio B. FIG. .
That is, in the example shown in FIG. 10A, among the frames received by the digital radio base station B via the network, the data of the frames 1 to 4 and the frame 8 are normally demodulated. In this example, there is a delay from frame 4 to frame 5 (Frame L), and data is lost (Frame ×) in frames 5 to 7. When such received and demodulated data is reconstructed into a frame signal, as shown in FIG. 10 (b), the frame cannot be reconstructed for a frame that is delayed or missing data, and is lost (blank). .

When the digital wireless device B receives and decodes a signal with a missing frame in this way, normal speech decoding is impossible in the receiver's demodulator (Vocoder), and a very unpleasant sound is output from the speaker.

Normally, in a digital mobile communication terminal, even if a data loss or delay is included in a received and demodulated frame, data can be demodulated normally by performing data restoration by error correction. In addition, in the unlikely event that restoration is not possible, the data is discarded by error detection, but in general, by repeating and outputting a normal audio signal received and demodulated before that, sound interruption is prevented, Further, when data is discarded for a long period of time, a mute process is performed to prevent generation of difficult sounds. However, as described above, if the frame itself is lost, error correction and error detection become impossible, so that sound cut-off prevention and mute processing are not performed, and it is not possible to prevent the output of difficult sounds.

Such troubles not only occur in radio base station apparatuses, but also in repeater apparatuses and radio relay apparatuses that similarly include a radio relay function, and those similar to radio base station apparatuses in multi-access (cellular) cellular phone systems. Can also be a problem.
The present invention has been made in view of various problems related to data frame relay processing in a radio base station apparatus and a radio relay apparatus used in such a conventional digital communication system. Digital radio system, radio base station apparatus and radio relay apparatus capable of preventing unintelligible sounds from being output in mobile communication terminals and terminal devices that receive and demodulate data even when data is delayed or missing The purpose is to provide.

In order to solve such a problem, the present invention according to the first aspect receives and demodulates a digital radio signal configured as a frame signal including a synchronization word, and includes the obtained digital data again including the synchronization word. In a radio base station apparatus that reconstructs a frame signal and transmits it as a digital radio signal, means for determining whether or not the data in the received and demodulated frame has been normally acquired, and when normal data is acquired, When data is set as data of the frame and normal data cannot be acquired, the frame includes means for setting any one of IDLE data, data indicating a CRC error, and data indicating an FEC error in the frame.

The present invention according to a second aspect relates to a radio relay apparatus, and first and second radio base station apparatuses including at least one controller for control channel and a plurality of controllers for communication channel are connected via a communication line. In the connected wireless relay device, one of these wireless base station devices receives and demodulates a digital wireless signal configured as a frame signal including a synchronization word transmitted by the first mobile communication terminal, and the obtained digital Means for transferring data to the other radio base station apparatus via the communication line, and the other radio base station apparatus acquires the data of the frame to be transmitted in the transferred digital signal before transmission; Means for determining whether or not, if data is acquired, means for reconstructing the data as data of the frame, If it cannot be obtained, the frame is reconstructed by setting any one of IDLE data, data indicating a CRC error, and data indicating an FEC error to the frame, and the frame signal including the reconstructed synchronization word is digitally converted. Means for retransmitting as a radio signal to the second mobile communication terminal.

The present invention according to a third aspect relates to a digital radio system, wherein a plurality of radio base station apparatuses are connected via a communication network, and an arbitrary mobile communication terminal is configured as a frame signal including a synchronization word. In a digital communication system that communicates with other mobile communication terminals via the radio base station apparatus by a signal, the radio base station apparatus receives and demodulates a digital radio signal transmitted from the mobile communication terminal, Means for transferring the obtained digital data to another required radio base station apparatus via the network, and the other radio base station apparatus that has received the transfer transmits a frame to be transmitted in the transferred digital signal. A means for determining whether or not the data has been acquired before transmission, and if the data has been acquired, If the data was reconstructed and data could not be acquired, the frame was reconstructed by setting any one of IDLE data, CRC error data, and FEC error data to the frame Means for retransmitting a frame signal including a synchronization word as a digital radio signal to the other mobile communication terminal.

In the digital radio system according to the third aspect of the present invention, preferably, the mobile communication terminal receives an IDLE in a frame when receiving and demodulating a signal transmitted from the radio base station apparatus or radio relay apparatus. If any of data, data indicating a CRC error, or data indicating an FEC error is included, the audio output is muted for the frame, or the received audio demodulated before is repeatedly output. Composed.

In the digital wireless system according to the third aspect of the present invention, in the mobile communication terminal, preferably, when the received frame is an IDLE frame, when the IDLE frame is first received, the mobile terminal repeats the operation. When IDLE continues for a plurality of predetermined frames or more, a mute operation is performed.

In the present invention according to the first, second, and third aspects, the frame structure of the frame is preferably composed of a synchronization word, frame structure information, control information, and speech coding information.

In the digital radio system according to the present invention, the voice encoded information may be stolen as control information.
Also, in the system, there is provided means for reconfiguring the frame by setting any one of IDLE data, data indicating a CRC error, and data indicating an FEC error in the frame, and the means steals the sound from the frame. It is also possible to construct a frame, in which the synchronization word and the frame structure information are set in a voice steal frame, and IDLE data is set in data for transmitting control information in the frame.

The system further comprises means for reconfiguring the frame by setting any one of IDLE data, data indicating a CRC error, and data indicating an FEC error in the frame. In the construction, the synchronization word and the frame structure information are set in the voice frame, the data in which the CRC causes an error on the receiving side is set in the data for transmitting the control information in the frame, and the voice is set. It can also be configured to set data in which the FEC of the encoded data causes an error on the receiving side.

As described above, the present invention receives and demodulates a digital radio signal configured as a frame signal including a synchronization word, reconstructs the obtained digital data into a frame signal including a synchronization word, and then converts it into a digital radio signal. In the transmitting radio base station apparatus, it is determined whether or not the data in the received and demodulated frame has been normally acquired. When normal data is acquired, the data is set as the data of the frame. Instead, the frame is reconstructed by setting any one of IDLE data, CRC error data, and FEC error data. Therefore, in mobile communication terminals and other communication terminals that receive these frame signals, systematic mute (silence) processing for IDLE data, CRC error data, and FEC error data, or previously demodulated audio is performed. If it functions so as to output repeatedly, it is possible to prevent unpleasant sound from being output from a speaker or the like. Also, it is possible to construct a wireless relay device or a digital wireless system that provides the same effect using the same principle.

The flowchart which shows one Example of the relay process of the data frame in the radio base station apparatus which concerns on this invention. The frame block diagram which shows an example of the relay process of the data frame in the radio base station apparatus which concerns on this invention. The figure which shows the specific example of the frame structure in the radio base station apparatus to which this invention is applied. The flowchart which shows the content of the control processing in the digital radio | wireless machine B which concerns on the Example of this invention. The flowchart which shows the other Example of the relay process of the data frame in the radio base station apparatus to which this invention is applied. The frame block diagram in the other Example of the relay method of the data frame of this invention. The frame block diagram which shows the other specific example to which this invention is applied. 1 is a schematic block diagram illustrating an example of a digital wireless relay device to which the present invention is applied. 1 is a schematic block diagram illustrating an example of a digital wireless device to which the present invention is applied. The figure which shows an example of the frame structure in a digital radio system. It is a figure for demonstrating the conventional malfunction, (a) is the frame figure which the digital radio base station received via the network, (b) is the figure of the frame which a digital radio base station reconstructs and resends.

10, 11 digital radio, 12, 13 digital radio base station (device), 23 codec circuit, 34 DSP, 25 CPU (microcomputer), FSW frame synchronization word

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .
FIG. 1 is a flowchart showing an example of data frame relay processing (method) in a radio base station apparatus according to the present invention. This example shows the processing in the above-described digital radio base station B shown in FIG. 7, that is, the radio base station nearest to the mobile communication terminal (digital radio B) which is the communication partner side.
At this time, the digital radio base station B acquires data from the network and secures data for a certain number of frames before starting transmission. If the number of frame data secured is large, it leads to audio delay. If the number of frame data is too small, data loss is likely to occur. Therefore, data is secured on the basis of no problem in normal operation. When transmission is started, frames are continuously transmitted until transmission is completed.

When the process starts, first, data is acquired from the network (S1). When it is determined that the frame transmission is started when retransmitted to the digital wireless device B (S2), it is determined whether or not data on the frame to be transmitted is obtained from the network (S3). If frame data is obtained, it is determined that “data is present” (S3, Yes), and the process proceeds to step S4. The obtained data is set as frame data (S4) and frame transmission is performed (S5). If the frame data is missing, the determination in the process S3 is “no data for the corresponding frame” (S3, No), and therefore “IDLE data” is set for the frame (S6). Is transmitted (S5).
Data acquired from the network is reconstructed as a frame and counted in units of frames. If the frame count is less than the specified value, the corresponding frame data cannot be obtained.

FIG. 2 is a diagram showing an IDLE frame as a result of the above processing. After setting FSW (frame synchronization word) and link channel information (LICH), a low-speed associated channel (SACCH), a high-speed associated channel (FACCH) ) Is set to “IDLE data”.

FIG. 3 shows an example of a frame structure when the present invention is applied to the demodulated data shown in FIG. 11. In frames 1 to 4, it is determined that “data is present” (S3, Yes), The process proceeds to step S4, where the obtained data is set in a frame (S4) and frame transmission is performed (S5). Further, since data is missing for the frames 5 to 7, the determination in the process S3 is “no data of the corresponding frame” (S3, No), and “IDLE data” is set for the frame (S6). ) And frame transmission (S5). As a result, even if the digital radio base station B demodulates a frame including a data delay or loss as shown in FIG. 3A, as shown in FIG. ) Will be retransmitted in the absence of a frame.
Therefore, in the digital wireless device B that receives and demodulates these digital signals, the “IDLE data” is subjected to a process of repeatedly outputting a normal demodulated sound obtained previously or a mute process. If a delay frame or a missing frame occurs instantaneously, if the mute process is selected, the sound will be interrupted, so the repeated process is more suitable. However, if a delayed frame or a missing frame continues for a relatively long time, the repetition process becomes unnatural. Specifically, the state of the received frame is stored, and two or more “IDLE frames” continue. In the case where there is an error (ie, when both the previous frame and the current frame are IDLE), mute is selected. FIG. 4 is a flowchart showing the contents of control processing performed in the digital radio base station B shown in FIG. 8, that is, the digital radio device B on the communication partner side.

As shown in FIG. 4, in the digital radio B, when the process starts, data is received (SS1), and when it is determined that the current frame is IDLE (SS2), the previous frame is IDLE. (SS3), if it is determined to be IDLE, mute processing is performed (SS4), and finally the current data state is stored (SS5), and the control processing is terminated. On the other hand, if it is determined in step SS2 that the current frame is not IDLE, the current data state is stored as it is (SS5), and the control process is terminated. If it is determined in step SS3 that the previous frame is not IDLE, the process is repeated (SS6), the current data state is stored (SS5), and the control process is terminated. .

In FIG. 4, only one frame before is targeted, so the explanation is for muting when two frames are consecutive IDLE frames. However, when multiple frames are stored by storing several past frames, Can be changed to mute. Further, it may be detected by a method of providing a counter to determine whether or not the IDLE frame is +1 in the case of an IDLE frame, and clearing other than that.
In FIG. 3, when the IDLE frame is set due to the omission and delay after frame 4 and the radio device that has received this is in a mute state continuously after repeated processing, and when frame data is obtained in frame 8, Audio output has been resumed. By operating in this way, it is possible to solve the problem that meaningless or hard to hear sound is output from a speaker or the like.
The present invention is not limited to this example and can be variously modified. FIG. 4 is a flowchart showing another embodiment of the present invention. In the data frame relay method in the radio base station apparatus shown in this example, when frame data cannot be obtained, “FEC error” data is inserted instead.

FIG. 5 also shows processing in the digital radio base station B shown in FIG. 8 described above, that is, the radio base station apparatus on the communication counterpart side. When the process starts, data is acquired from the network (S11). If it is determined that it is the start of frame transmission when retransmitting to the digital radio B (S12), it is determined whether data is obtained for the frame to be transmitted (S13). If frame data is obtained, it is determined that “data is present” (S13, Yes), and the process proceeds to processing S14, where the obtained data is set as a frame (S14) and frame transmission is performed (S15).

On the other hand, if it is determined in S13 that frame data is missing (S13, No), “FSW” is set for the frame (S16), and then the CRC error low-speed associated channel (SACCH) and After setting data such that the number of FEC error bits is determined to be an error (in the digital radio terminal) as “error voice data” in the voice channel (VCH) (S17, S18), frame transmission is executed (S15). ). FEC (Forward Error Correction) is a forward error detection / correction method in which redundant data for error detection / correction is added before data transmission, and if there is an error, correction is performed on the receiving side. However, in this example, using this function, data selected so as to be judged as “FEC error” on the receiving side is inserted.

FIG. 6 is a frame diagram showing an example of the result of the above processing, and it is a low-speed associated channel (SACCH) following FSW (frame synchronization word) and link channel information (LICH), and data cannot be obtained. Data indicating “CRC error” is inserted into the frame, and data indicating “FEC error” is inserted into the voice channel (VCH) from which subsequent data cannot be obtained.

FIG. 7 shows an example of a frame configuration when the modified example of the present invention is applied to the demodulated data shown in FIG. That is, it is determined that “data is present” in frames 1 to 4 (S13, Yes), the process proceeds to step S14, the obtained data is set as a frame (S14), and frame transmission is performed (S15). ). On the other hand, since the data for frame 5 is delayed, the determination in the process S13 is “no data for the corresponding frame” (S13, No), and data indicating “CRC error” is set for the frame (S17). ) In the subsequent VCH, “error frame” data having a large number of error bits such as “FEC error” is inserted. As a result, even if the digital radio base station B demodulates a frame including data delay or omission as shown in FIG. 7A, as shown in FIG. ) Is not transmitted, and data indicating “CRC error” and “FEC error” is embedded in that portion and retransmitted.

Therefore, in the digital radio B that receives and demodulates these digital signals, the process of repeatedly outputting the normal demodulated sound obtained previously, as in the embodiment described with reference to FIGS. 1 to 3, or Since the sound is muted by the mute process, it is possible to solve the problem that a meaningless or hard to hear sound is output from a speaker or the like that occurs when a frame is transmitted in a blank state. In particular, in this modified embodiment, all frames for which data cannot be obtained are filled with data that causes them to be processed as errors, so that they can be used for general purposes.
In the above-described embodiment, since the correct symbol data is added to the FSW and LICH of the frame to be retransmitted, the IDLE process is performed while maintaining the synchronization in the receiving digital radio, and other data and Audio can be made an error.

In the above description of the embodiment, the case where data loss or delay occurs in communication between wireless base stations connected by the network in FIG. 8 has been described. This operation is related to data transmitted from a mobile station. Is also applicable. That is, when the frame data transmitted by the digital radio A is lost or delayed for some reason (such as radio wave interference or multipath), the digital radio base station A that receives it has the operations described above. Similarly, transmission data to be relayed and data to be transmitted to the digital base station B can be replaced with IDLE data, data indicating a CRC error, and data indicating an FEC error.

Further, the present invention can be similarly adopted even when an audio signal is encrypted. That is, if the relationship between the frame position data and the audio data is constant or there is no information indicating them, it is often impossible or difficult to decrypt the code. Even when data cannot be obtained, an empty frame is not generated by transmitting an IDLE frame or an error-only frame. Therefore, since the relationship between the frame order (SACCH) and the voice channel (VCH) can be maintained, the system can be employed without any trouble in a system in which voice is encrypted.
In general, audio decoding processing in the receiving terminal device is executed in lower layer processing such as a DSP, but the present invention can execute processing such as data discrimination in the processing. It can be performed independently of the processing in the upper layer. Therefore, high-speed processing can be performed without increasing the load on the microcomputer.

The present invention need not be limited to the above-described embodiments. Similarly, other than “IDLE data”, “data indicating a CRC error”, and “data indicating an FEC error”, the communication system can be a mobile communication system. On the terminal side, it is also possible to set a signal or data having a function of restricting audio output instead of the missing frame data. If there is no such data or signal in the system, it will be possible to assign unique data and signals for that purpose.

Although an example of the present invention has been described above, it goes without saying that application to other systems and various modifications are possible without being limited to this example.
Further, by programming the frame relay processing procedure of the present invention in accordance with an OS that can be controlled by a computer, any computer equipped with the OS can be controlled by the same processing method. Further, these programs are written on a recording medium such as a CD-ROM, and the CD-ROM is mounted on a medium driving device such as a CD-ROM drive mounted on the computer. It goes without saying that the object of the present invention is achieved by storing in a memory or storage device and executing it.
As a recording medium for storing the program, a semiconductor medium (for example, ROM, nonvolatile memory card, etc.), an optical medium (for example, DVD, MO, MD, CD, etc.), a magnetic medium (for example, magnetic tape, flexible disk, etc.) ) Or the like.

Claims

A radio base station apparatus that receives and demodulates a digital radio signal configured as a frame signal including a synchronization word, and reconstructs the obtained digital data into a frame signal including a synchronization word, and then transmits the digital data as a digital radio signal. ,
Means for determining whether or not the data in the received and demodulated frame has been normally acquired;
When normal data is acquired, the data is set as data of the frame. When normal data cannot be acquired, any of IDLE data, CRC error data, and FEC error data is included in the frame. A radio base station apparatus comprising means for setting the above.
In a radio relay apparatus in which two first and second radio base station apparatuses including at least one control channel controller and a plurality of communication channel controllers are connected via a communication line,
One of the first and second radio base station apparatuses receives and demodulates a digital radio signal configured as a frame signal including a synchronization word transmitted by the first mobile communication terminal and transmits the obtained digital data. Means for transferring to the other radio base station apparatus via the communication line;
Then, the other radio base station apparatus determines whether or not the data of the frame to be transmitted in the transferred digital signal has been acquired before transmission, and, if acquired, the data of the frame Means for reconstructing as data, and means for reconstructing a frame by setting IDLE data, data indicating a CRC error, or data indicating an FEC error in the frame if the data cannot be acquired; Means for retransmitting a frame signal including the constructed synchronization word as a digital wireless signal to the second mobile communication terminal.
A plurality of radio base station apparatuses are connected via a communication network, and an arbitrary mobile communication terminal is connected to another mobile communication terminal via the radio base station apparatus by a digital radio signal configured as a frame signal including a synchronization word. A digital wireless system that communicates with a machine,
The radio base station apparatus includes means for receiving and demodulating a digital radio signal transmitted from the mobile communication terminal and transferring the obtained digital data to another required radio base station apparatus via the network. ,
The other radio base station apparatus that has received the transfer has means for determining whether or not the data of the frame to be transmitted in the transferred digital signal has been acquired before transmission, and if the data has been acquired, If the data is reconstructed as data of the frame and the data cannot be acquired, means for setting the IDLE data, data indicating a CRC error, or data indicating an FEC error in the frame to reconstruct the frame; Means for retransmitting a frame signal including the reconstructed synchronization word as a digital wireless signal to the other mobile communication terminal.
When the mobile communication terminal receives and demodulates a signal transmitted from the radio base station apparatus or the radio relay apparatus, the frame includes any one of IDLE data, CRC error data, and FEC error data. 4. The digital radio system according to claim 3, wherein the digital radio system is configured to mute the audio output for the frame, or to repeatedly output the received audio demodulated before that.
In the mobile communication terminal, when the received frame is an IDLE frame, the IDLE frame is first received, and when the IDLE frame is received for the first time, the IDLE frame is repeatedly operated. The wireless relay device according to claim 2, configured to do so.
In the mobile communication terminal, when the received frame is an IDLE frame, the IDLE frame is first received, and when the IDLE frame is received for the first time, the IDLE frame is repeatedly operated. The digital radio system according to claim 3, configured to do so.
The radio base station apparatus according to claim 1, wherein a frame structure of the frame includes a synchronization word, frame structure information, control information, and speech coding information.
The radio relay apparatus according to claim 2, wherein a frame structure of the frame is configured by a synchronization word, frame structure information, control information, and audio coding information.
The digital radio system according to claim 3, 4 or 6, wherein a frame structure of the frame is composed of a synchronization word, frame structure information, control information, and speech coding information.
10. The digital radio system according to claim 9, wherein the voice encoded information can be stolen as control information.
The means for reconstructing a frame by setting any one of IDLE data, data indicating a CRC error, and data indicating an FEC error in the frame constructs the frame into a frame in which audio is stealed. 11. The digital radio system according to claim 10, wherein the word radio and the frame structure information are set in a voice still frame, and IDLE data is set in data for transmitting control information in the frame.
The frame includes means for reconstructing a frame by setting any one of IDLE data, data indicating a CRC error, and data indicating an FEC error, and the reconstructing means constructs the frame into an audio normal frame. In the construction, the synchronization word and the frame structure information are set in the voice frame, the data in which the CRC causes an error on the receiving side is set in the data for transmitting the control information in the frame, and the FEC of the voice encoded data is set. The digital wireless system according to claim 10, configured to set data that causes an error on a receiving side.