Radio communications system

Abstract

To cause a radio communications system to effectively evaluate a voice quality after a transmission.SOLUTION: A transmitter 10 transmits a trial voice data to a mobile station 20. The mobile station 20 transmits the trial voice data to be received to the transmitter 10 as replay data. The transmitter 10 compares a source trial voice data with the trial voice data contained in the replay data.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a wireless communication system in which audio signals are transmitted by wireless communication between a transmitter and a receiver. [Background technology]

[0002] For example, in a wireless communication system for railways, multiple base stations connected to a central control device for monitoring the entire system are placed at various locations on the ground. Meanwhile, multiple railway cars moving on the ground are each provided with a mobile station, and as the railway car moves, the mobile station of the railway car can communicate with the central control device by wirelessly communicating with one base station that can wirelessly communicate with the mobile station. This point is the same whether transmission is from the central control device or from the mobile station.

[0003] For example, an administrator can transmit voice signals to each railcar (mobile station: receiver) from a transmitter connected to a central control device, but the quality of the voice (voice quality) played back on the mobile station side at this time depends on the communication conditions, which vary according to the position, environment, etc. For this reason, a technology is used that recognizes the communication conditions with each mobile station by evaluating such voice quality.

[0004] Patent Document 1 describes a technique in which a test signal (test voice data, pseudo-random noise pattern) is inserted into the slots of a downlink signal emitted from the base station and an uplink signal transmitted from the mobile station, and the mobile station and base station each evaluate (voice quality evaluation, bit error rate) this test signal in the downlink signal received by the mobile station and the uplink signal received by the base station. In this case, the voice quality is evaluated by an operator who actually listens to the voice. If the test voice data is determined in advance, the operator can perform this evaluation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2014-99690 A DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0006] In the above technology, the voice quality was evaluated only on the receiving side (the mobile station for the downlink signal, and the base station for the uplink signal). In this case, an operator is required to evaluate the voice quality at each side, and it is not appropriate for the train operation to have the crew at the mobile station (railroad car) frequently perform such evaluations.

[0007] Therefore, it is desirable to be able to more efficiently evaluate the post-transmission voice quality in a wireless communication system.

[0008] The present invention has been made in view of the above circumstances, and has an object to solve the above problems. [Means for solving the problem]

[0009] The present invention is a wireless communication system having a transmitter that transmits voice data to a receiver side, and the receiver, wherein the transmitter transmits test voice data to the receiver, the receiver has a data response unit that transmits reply data including the received test voice data to the transmitter side, and the transmitter has a voice quality evaluation unit that calculates a voice quality evaluation result by comparing the test voice data included in the reply data with the transmitted test voice data. In the receiver, the data response unit may transmit additional information including its own location information at the time the test voice data was received to the transmitter together with the response data, and the transmitter may store the received additional information together with the voice quality evaluation result. The additional information may include reproduction information relating to an error that occurs when the test audio data is reproduced on the receiver side. Effect of the Invention

[0010] According to the present invention, it is possible to more efficiently evaluate the post-transmission voice quality in a wireless communication system. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating a configuration of a wireless communication system according to an embodiment. [Diagram 2] 1 is a diagram illustrating a configuration of a transmitter in a wireless communication system according to an embodiment. [Diagram 3] 1 is a diagram showing a configuration of a mobile station (receiver) in a wireless communication system according to an embodiment. [Figure 4] 10 is a sequence diagram showing an operation of evaluating voice quality in the wireless communication system according to the embodiment. FIG.

[0012] Next, a wireless communication system according to an embodiment of the present invention will be described in detail. Fig. 1 is a simplified diagram showing the configuration of this wireless communication system 1. Here, a transmitter 10 has a function of transmitting an audio signal, and a mobile station (receiver) 20 has a function of receiving the signal, but as will be described later, the same operation is possible even when communication is performed in the opposite direction.

[0013] Here, a plurality of mobile stations 20 are provided corresponding to a plurality of railway vehicles T. Each mobile station 20 is mounted on a railway vehicle, and since a plurality of railway vehicles move along various routes, the position of each mobile station 20 changes from moment to moment.

[0014] The transmitter 10 is connected to a central control device 30 fixed on the ground, and the central control device 30 is connected to a base station 40. However, by installing a plurality of base stations 40 at different locations on the ground, when a mobile station 20 moves, one of the base stations 40 can perform digital wireless communication with the mobile station 20. Therefore, for example, when transmitting a voice signal from the transmitter 10 to a specific mobile station 20, the voice signal is transmitted to the mobile station 20 via one base station 40 that can communicate with the mobile station 20.

[0015] In the above configuration, the transmitter 10, the central control device 30, and the base station 40 are connected by wires, and the base station 40 and the mobile station 20 are connected by digital wireless communication. However, since a plurality of base stations 40 are provided, the central control device 30 and each base station 40 are actually connected via a network. When voice data is transmitted from the transmitter 10 to the mobile station 20 and the voice data is reproduced on the mobile station 20 side, if the quality (voice quality) of the voice data is deteriorated compared to the original voice data, this deterioration is often caused by the state of wireless communication between the base station 40 and the mobile station 20. Unlike between the base station 40 and the mobile station 20, the transmitter 10, the central control device 30, and the base station 40 are connected by wires and the positional relationship between them is fixed, so that the deterioration of the voice quality during communication between them is small, or can be set to be small.

[0016] Here, the transmitter 10 generates test audio data similar to that described in Patent Document 1, for example, and transmits it as an audio signal to the mobile station 20. At this time, the test audio data is encoded by the transmitter 10, and a carrier wave modulated by the audio signal including the encoded data is emitted from the transmitter 10. The mobile station 20 receives the carrier wave and demodulates and decodes it to obtain the test audio data.

[0017] The quality of the voice signal (voice quality) changes depending on the state of wireless communication between the mobile station 20 and the base station 40, and is evaluated in the wireless communication system 1. This point is also similar to the technology described in Patent Document 1. However, unlike the technology described in Patent Document 1, the evaluation of the voice quality is not performed on the mobile station 20 side, but instead, the mobile station 20 re-encodes the acquired test voice data and transmits it to the transmitter 10 side as reply data. The transmitter 10 receives this and decodes the test voice data from the received reply data. Then, it compares it with the test voice data it previously transmitted and evaluates the voice quality. This allows the transmitter 10 side to recognize the communication state with the mobile station 20. At this time, the mobile station 20 side returns the test voice data to the transmitter 10, so there is no need for an operator to check the received test voice data. Also, the transmitter 10 side evaluates the voice quality by comparing the previously transmitted test voice data with the returned test voice data, so there is no need for an operator to evaluate the voice quality. Therefore, this evaluation can be easily and accurately performed without the help of an operator.

[0018] Furthermore, when the mobile station 20 returns the reply data, it can transmit additional information (additional information) that is useful for understanding the communication status together with the reply data. Such additional information includes, for example, the position information of the mobile station 20 (railroad vehicle T) at this time point, and information regarding an error that occurs when decoding the test voice data from the received signal. This allows, for example, when there is a deterioration in voice quality, the transmitter 10 (or the central control device 30) to determine whether the deterioration is caused by the communication environment with the mobile station 20 or by an abnormality occurring on the mobile station 20 side.

[0019] The configurations of the transmitter 10 and mobile station (receiver) 20 for performing this operation will be specifically described below. Fig. 2 shows the configuration of the transmitter 10, and Fig. 3 shows the configuration of the mobile station 20. Here, for example, the mobile station 20 is a wireless terminal, and therefore actually has various functions, but only the components directly related to the present invention are described here. The same applies to the transmitter 10.

[0020] First, a normal operation of transmitting a normal voice signal from the transmitter 10 to the mobile station 20 and outputting it at the mobile station 20 will be described. The transmitter 10 shown in Fig. 2 is provided with a voice input unit 11 to which voice instructions issued by, for example, an administrator are input. The voice data generated in this way is coded by the coding unit 12, and a voice signal including the coded voice data is output from the transmitting unit 13. In this case, the voice signal is divided into packets with a fixed data capacity and transmitted. In Fig. 1, this signal is transmitted to the mobile station 20 via the central control device 30 and the base station 40.

[0021] 3, a receiving unit 21 receives this voice signal, and the transmitted voice data is reproduced by decoding the voice data in a decoding unit 22. This voice data is outputted from a voice output unit 23, which is, for example, a speaker, so that a user (railroad crew member) on the mobile station 20 side can hear it.

[0022] The above configuration and operation in Figures 2 and 3 are no different from those in conventional railway radio systems. Next, the parts in particular related to the evaluation of the voice quality and the operation involved will be described. Figure 4 is a sequence diagram of this operation.

[0023] The transmitter 10 shown in Fig. 2 is provided with a voice quality evaluation unit 14 having a processor and the like for evaluating voice quality. The voice quality evaluation unit 14 acquires test voice data, which is a predetermined voice pattern (S101 in Fig. 4). The contents of the test voice data are set appropriately, and for example, the same as that described in Patent Document 1 can be used. The test voice data is stored in, for example, a storage unit 17 as described below.

[0024] The voice quality evaluation unit 14 inputs this test voice data to the encoding unit 12 in the same manner as the above-mentioned voice data, encodes the test voice data (S102 in FIG. 4), and transmits a voice signal including the encoded test voice data to the mobile station 20 via the transmission unit 14 (S103 in FIG. 4).

[0025] In the mobile station 20 shown in Fig. 3, this signal is received by the receiver 21 in the same manner as in the case of the above-mentioned voice signal (S104 in Fig. 4), and the test voice data is similarly decoded by the decoder 22 (S105 in Fig. 4). At this time, the additional information generator 24 obtains information (reproduction information) relating to errors during decoding and location information of the mobile station 20 as additional information (additional information) to be used when evaluating the voice quality (S106 in Fig. 4). Details of the additional information will be described later.

[0026] The test voice data decoded here is transmitted to the transmitter 10 as reply data. In the mobile station 20, a data reply unit 25 is provided for this purpose. The data reply unit 25 is composed of an encoding unit 25A and a transmission unit 25B. Here, the decoded test voice data is re-encoded by the encoding unit 25A (S107 in FIG. 4), and reply data including the re-encoded test voice data and additional information is transmitted (returned) to the transmitter 10 (base station 40) (S108 in FIG. 4). Here, the encoding method used in the encoding unit 25A is assumed to be the same as that of the encoding unit 12 in the transmitter 10. In the mobile station 20, a control unit 26 having a processor for controlling the whole to perform such operations, and a storage unit 27 for storing data and the like required for these operations are provided.

[0027] The transmitter 10 in Fig. 2 is provided with a reply data reproducing unit 15 that reproduces test voice data included in the received reply data. The reply data reproducing unit 15 is composed of a receiving unit 15A and a decoding unit 15B. Here, the reply data is received by the receiving unit 15A (S109 in Fig. 4), decoded by the decoding unit 15B (S110 in Fig. 4), and the test voice data is reproduced (S111 in Fig. 4). At this time, the additional information is also read out in the same manner.

[0028] The reproduced test audio data is input to the audio quality evaluation unit 14, and the audio quality evaluation unit 14 can compare (S112 in FIG. 4) the test audio data that it previously input to the encoding unit 12 (S101, S102 in FIG. 4) with the reproduced test audio data (S111 in FIG. 4).

[0029] This comparison can be performed, for example, by using a well-known voice evaluation (recognition) method, and the difference can be quantified and evaluated accurately. In Fig. 2, the transmitter 10 is provided with a control unit 16 having a processor for controlling the whole system to perform such operations, and a storage unit 17 for storing data required for the operations. The control unit 16 causes the voice quality evaluation unit 14 to store the evaluation result and additional information in association with each other in the storage unit 17 (S113 in Fig. 4).

[0030] In the above operation, the evaluation of the voice quality using the test voice data is performed by the transmitter 10, which is the transmitting side. At this time, the mobile station 20 side performs a process of re-encoding the reproduced test voice data and returning it as an uplink signal, but this process can be performed automatically when the test voice data is received. Therefore, there is no need for an operator on the mobile station 20 side to perform any work in the evaluation of the voice quality. Also, as described above, this evaluation is performed instead on the transmitter 10 side, but in this case, the voice quality evaluation unit 14 performs this evaluation by comparing the transmitted test voice data (S101, S102 in FIG. 4) with the reproduced test voice data (S111 in FIG. 4). Therefore, there is no need for an operator on the transmitter 10 side to perform this evaluation.

[0031] In addition, in the above configuration, predetermined test voice data is used, but this test voice data can be set as a pattern that makes it easy to evaluate the voice quality, and can be stored in advance in storage unit 17, similar to the technology described in Patent Document 1. Here, in the case of the technology described in Patent Document 1, it is necessary for the mobile station side (operator) to recognize the transmitted test voice data in advance. In other words, it is necessary for the test voice data to be commonly recognized on the transmitter side and all mobile stations.

[0032] On the other hand, in the above configuration, the transmitter 10 can re-encode any test voice data it has transmitted at the mobile station 20 before returning it, and can reproduce the returned test voice data. At this time, the mobile station 20 (or an operator at the mobile station 20) does not need to recognize the contents of the test voice data, and can perform this operation on any test voice data. In this case, the above-mentioned comparative evaluation is possible for any test voice data. Therefore, in practice, any voice can be used as the test voice data.

[0033] In the above operation, the deterioration of the voice quality mainly reflects the communication status between the base station 40 and the mobile station 20. For example, in the technology described in Patent Document 1, only a downlink signal is used, so only a single degradation in the downlink direction between the base station 40 and the mobile station 20 is reflected in the voice quality. In contrast, in the above operation, the deterioration in the two directions, the downlink direction and the uplink direction, in this section are reflected in the voice quality. In this case, the time from when the mobile station 20 receives a downlink signal to when it performs the above-mentioned processing and issues an uplink signal is actually short, and the change in the situation of the mobile station 20 and the moving distance during such a short time are small. Therefore, it can be considered that this evaluation essentially reflects the communication status when the mobile station 20 is at a certain location. Alternatively, in this method, the deterioration is amplified and detected twice, that is, uplink and downlink, so that the deterioration can be detected with higher sensitivity than the technology described in Patent Document 1.

[0034] Next, the additional information will be described. In the above operation, when the mobile station 20 returns the test voice data as an uplink signal, it is effective to use various types of additional information that are related to the evaluation of voice quality (or communication conditions) and cannot be recognized by the transmitter 10 alone. Such additional information includes the location information of the mobile station 20, since the location of the mobile station 20 varies. For this reason, in FIG. 3, the mobile station 20 is provided with a location information recognition unit 28 that recognizes its own location by a GPS signal. The additional information creation unit 24 recognizes this location information as additional information, and can generate an uplink signal by storing this additional information in a slot different from the reply data. Note that the mobile station 20 does not need to recognize the location information itself, and the mobile station 20 may recognize the location information from the railway vehicle T. Also, reply data including the additional information may be generated.

[0035] In this case, the voice quality evaluation unit 14 on the transmitter 10 side can recognize the correspondence between voice quality and this location information, and can store this in the storage unit 17. When the mobile station 20 moves and multiple mobile stations 20 are installed, the data at multiple points in time are accumulated, making it possible to recognize the correspondence between deterioration of voice quality and the area where it occurs.

[0036] The additional information may be information other than the position information, such as information related to an error that occurs during decoding in the decoding unit 22 (reproduction information).

[0037] An example of the reproduction information is a packet loss rate. The operation of decoding the downlink signal on the mobile station 20 side is performed for each packet. At this time, if there is a packet that cannot be decoded (received), the mobile station 20 side requests the transmitter 10 side to retransmit this packet, or the data of this packet is lost. Such a situation is also caused by the communication conditions described above. For this reason, the decoding unit 22 in FIG. 3 can recognize the ratio of packets that could not be received in this way (packet loss rate). Alternatively, other than the packet loss rate, information regarding an error that occurred in the process of reproducing the test voice data in the decoding unit 22 can be used as this reproduction information (additional information).

[0038] When the voice quality evaluation unit 14 recognizes such location information, playback information, and voice quality as additional information from multiple mobile stations 20 at multiple points in time and stores them in the memory unit 17, it is possible to estimate whether deterioration in voice quality, packet loss, etc. is caused by a worsening communication situation or an abnormality (failure) of the mobile station 20.

[0039] For example, if the voice quality degradation or packet loss rate is large in all mobile stations 20 in the vicinity of a certain point, it can be assumed that this is due to the communication environment (the location of the mobile station 30). Conversely, if the voice quality degradation or packet loss rate is large only in one mobile station 20 in the vicinity of a certain point, and such problems do not occur in all other mobile stations 20, it can be assumed that the problem is on the side of this one mobile station 20. This type of judgment is particularly effective in a railway radio system in which there are multiple mobile stations 20 and the movement route is fixed.

[0040] 4 can be performed at regular intervals, for example. This allows more of the above-mentioned data to be stored in the storage unit 17. From this data, an operator on the transmitter 10 side can accurately grasp the state of wireless communication in the entire wireless communication system 1 and the state of each mobile station 30. This determination can also be made by the control unit 16.

[0041] In the above example, the voice quality evaluation result and additional information are stored in the storage unit 17 of the transmitter 10. However, in the configuration of Fig. 1, this information can also be stored in the central control device 30 and the base station 40. Alternatively, this information can be shared by all the components in Fig. 1.

[0042] In the above configuration, the transmission of the voice signal is performed from the transmitter 10 side, and the only transmission from the mobile station (receiver) 20 side is the reply of this voice signal. However, in reality, since both the transmitter 10 and the mobile station 20 have the function of transmitting and receiving voice signals, for example, if a voice quality evaluation unit or the like is provided on the mobile station side, the transmitter 10 and the mobile station 20 can be interchanged for operation. That is, in a wireless communication system using devices that transmit and receive voice signals, the voice quality evaluation unit or the like is provided on some devices, and the data reply unit or the like is provided on the opposing device side, so that the same operation is possible. Therefore, the above configuration is effective in wireless communication systems in which voice signals are transmitted, other than railway wireless systems.

[0043] The present invention has been described above based on the embodiment. This embodiment is merely an example, and it will be understood by those skilled in the art that various modifications are possible in the combination of the respective components, and that such modifications are also within the scope of the present invention. [Explanation of symbols]

[0044] 1. Wireless communication systems 10 Transmitter 11 Audio input section 12 Encoding section 13 Transmitter 14 Voice quality evaluation section 15 Reply data playback section 15A Receiving section (reply data regeneration section) 15B Decoding section (reply data regeneration section) 16, 26 Control unit 17, 27 Memory section 20 Mobile station (receiver) 21 Receiving section 22 Decoding section 23 Audio output section 24 Additional Information Creation Department 25 Data Response Section 25A Encoding section (data response section) 25B Transmitter (Data Response Unit) 28 Location information recognition unit 30 Central Control Unit 40 base station T Railway vehicles

Claims

1. A wireless communication system having a transmitter for transmitting audio data to a receiver side and the receiver, The transmitter transmits test audio data to the receiver; The receiver includes: a data reply unit for sending reply data including the received test voice data to the transmitter side; The transmitter includes: a voice quality evaluation unit that calculates a voice quality evaluation result by comparing the test voice data included in the reply data with the transmitted test voice data; A wireless communication system comprising:

2. In the receiver, the data reply unit Transmitting additional information including the location information of the transmitter when the test voice data was received together with the reply data to the transmitter side; The transmitter includes:

2. The wireless communication system according to claim 1, wherein the received additional information is stored together with the voice quality evaluation result.

3. 3. The wireless communication system according to claim 2, wherein the additional information includes reproduction information relating to an error that occurs when the test audio data is reproduced on the receiver side.

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