Wireless Transmission System

Abstract

To provide a radio transmission system configured, in sequentially transmitting transmission data to be transmitted across multiple frames, to allow a receiving side to easily identify that pieces of data are identical, and enable combination of normal data, thereby improving a reception rate.SOLUTION: In a radio transmission system, a transmission apparatus sequentially transmits transmission data across multiple frames, when the transmission data is transmitted across the frames, including a check code for confirming an error of data within the frames in each of the frames. A mobile station device 4 or a base station device 3, serving as a receiving device, receives the transmission data a plurality of times. When an error data detection unit 32 detects an error in the transmission data, a data comparison / replacement unit 34 selects frames determined to be non-defective with the check code, in the multiple pieces of received transmission data, and synthesizes the selected frames by combination, to generate normal transmission data.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wireless transmission system, and particularly to a wireless transmission system capable of improving the reception rate for correctly receiving without error when transmitting transmission data continuously for multiple times across a plurality of frames.

Background Art

[0002] [Description of Prior Art: FIG. 7] The schematic configuration of a wireless transmission system used in a business wireless system will be described with reference to FIG. 7. FIG. 7 is a schematic configuration diagram of a general wireless transmission system. As shown in FIG. 7, the wireless transmission system includes a plurality of command stations 1-1 to 1-n (hereinafter simply referred to as command station 1 when n is not distinguished), a line control device 2, a plurality of base station devices 3-1 to 3-n (hereinafter simply referred to as base station device 3 when n is not distinguished), and a plurality of mobile station devices 4.

[0003] The command station 1 is connected to the line control device 2 and monitors and controls the wireless transmission system, or integrally monitors and controls a plurality of systems. In addition, the command station 1 communicates with the mobile station device 4 via the line control device 2 for calls and data transmission and reception.

[0004] The line control device 2 is connected to the command station 1 and the base station device 3, and performs switching control in the communication between the command station 1 and the mobile station device 4. The base station device 3 is wired-connected to the line control device 2 and wireless-connected to the mobile station device 4 to perform data transmission.

[0005] The mobile station device 4 is composed of an in-vehicle wireless device or a portable wireless device, and is a wireless communication terminal that can be operated while moving and while being fixedly installed. The mobile station device 4 performs data transmission by wireless communication with the base station device 3 within the service area of the base station device 3. Here, the wireless communication from the base station device 3 (upper device) to the mobile station device 4 (lower device) is called downlink transmission, and the reverse wireless communication from the mobile station device 4 to the base station device 3 is called uplink communication.

[0006] [Conventional Data Transmission] In a wireless transmission system as shown in FIG. 7, data is transmitted using radio waves (electromagnetic waves) from the mobile station device 4 to the base station device 3 and from the base station device 3 to the mobile station device 4. Since the wireless section propagates radio waves in space, it is assumed that the transmission data is likely not to be correctly propagated to the target device due to the influence of shielding and reflection by terrain and buildings.

[0007] Conventionally, there are cases where a method of decoding data is implemented by error correction techniques such as separating data and creating new data from the separated data according to certain rules. However, in error correction, if all the received data has errors, all the data may have to be discarded.

[0008] Also, when the transmission data becomes large, it is necessary to transmit the data across multiple frames during transmission. When transmitting across multiple frames, as the data length increases, the propagation time becomes longer, so it becomes more susceptible to the influence of the propagation environment such as changes in the surrounding environment.

[0009] Furthermore, conventionally, there has been something that attempts to improve the reception rate (transmission arrival rate) of normally receiving data by performing continuous transmission in which the same data is continuously transmitted multiple times, and generating normal data from the multiple data on the receiving side.

[0010] [Example of Conventional Bit Allocation: FIG. 8] An example of conventional bit allocation when transmitting data across multiple frames will be described with reference to FIG. 8. FIG. 8 is an explanatory diagram showing an example of bit allocation in a conventional wireless transmission system. In FIG. 8, an example of bit allocation and a transmission frame in a physical communication channel when transmitting data wirelessly are shown for a Fast Associated Control Channel (FACCH).

[0011] When the data to be transmitted is long and cannot be accommodated in one frame, the number of frames is increased according to the data length for transmission. In the example of FIG. 8, the transmission data is accommodated across N frames from the first frame 301-1 to the last frame 301-N. In the first frame 301-1, signal configuration information such as a frame number is stored in octet 1, information of an additional signal type including information for specifying transmission data is stored in octets 2 and 3, and transmission data is stored in octets 4 to 13.

[0012] In the intermediate frames 301-2 to 301-N-1, signal configuration information is stored in octet 1, and transmission data is stored in octets 2 to 13. Also, in the last frame 301-N, signal configuration information is stored in octet 1, transmission data is stored in octets 2 to 12, and a check code is stored in octet 13. Conventionally, a check code was provided only in the last frame 301-N, and the presence or absence of errors was detected for the entire data of the first frame 301-1 to the last frame 301-N.

[0013] Then, at the time of transmission, the first frame 301-1 is stored in transmission frame 1, the intermediate frame 301-2 is stored in transmission frame 2, and so on, and finally the last frame 301-N is stored in transmission frame N and transmitted.

[0014] [In the case of consecutive transmission: FIG. 9] Next, the transmission frame in the case of consecutive transmission will be described with reference to FIG. 9. FIG. 9 is an explanatory diagram showing an example of consecutive transmission in a conventional wireless transmission system. Note that FIG. 9 is an example in which the transmission data is accommodated across five frames, i.e., the head frame 301-1 to the final frame 301-5. Here, the case of double consecutive transmission in which the same data is transmitted twice in a row is shown.

[0015] As shown in FIG. 9, in the first transmission of the double consecutive transmission, as in FIG. 8, the head frame 301-1 to the final frame 301-5 are sequentially stored in the transmission frames 1 to 5 (indicated by the dashed line). In the second transmission, following the data of the first transmission, they are sequentially stored in the transmission frames 6 to 10 (indicated by the two-dot chain line) and then transmitted.

[0016] [Loss in Transmission Spanning Multiple Frames] However, when transmission is performed across multiple frames, if a loss occurs in the head frame 301-1 including the data type, the signal type of the transmission data becomes unknown, and all of the data may be undecodable and discarded. The same applies when consecutive transmission is performed and losses occur in the head frames in all of the multiple transmissions. That is, even if the frame in which the data loss has occurred is only the first one frame, all of the data will be discarded, resulting in poor data transmission efficiency.

[0017] [Related Art] Note that as a conventional technique related to a wireless transmission system, there is Japanese Patent Application Laid-Open No. 2000-59345, "Data Receiving Apparatus Using a Wireless Line" (Patent Document 1). Patent Document 1 describes generating normal data from consecutively transmitted or retransmitted data to increase the data reception rate. [Prior Art Documents] [Patent Documents]

[0018] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-59345 [Summary of the Invention]

Problems to be Solved by the Invention

[0019] As described above, in the conventional wireless transmission system, when transmission data is transmitted across a plurality of frames, even if an error occurs in some frames due to the propagation environment or the like, the entire transmission data rather than in frame units must be retransmitted, resulting in a problem of poor data transmission efficiency.

[0020] In particular, when an error occurs in the first frame, all the data of the plurality of frames must be discarded without using the frames that have been received normally, resulting in a problem of poor efficiency.

[0021] In addition, Patent Document 1 does not describe that when a transmission device transmits transmission data that spans a plurality of frames, the same sequence number and a check code for the frame are inserted into each frame and transmitted multiple times, and the receiving device refers to the check code for each frame of the plurality of received data, combines and synthesizes the data of the frames without errors from the received data with the same sequence number, decrypts the synthesized data, or outputs a retransmission request in frame units.

[0022] The present invention has been made in view of the above actual situation. When transmitting transmission data that spans a plurality of frames multiple times, the receiving device can combine the data of normal frames from among the plurality of incorrect transmission data to obtain normal data. Also, when there is a frame in which all of the consecutively transmitted transmission data is incorrect, a retransmission request is output in frame units to improve the reception rate and shorten the data transmission time associated with retransmission. An object of the present invention is to provide a wireless transmission system.

Means for Solving the Problems

[0023] The present invention for solving the problems of the above-described conventional examples is a wireless transmission system that performs data transmission using wireless communication. When the transmission data to be transmitted spans a plurality of frames, an error in the data within each frame is confirmed within each frame frame including a check code while performing consecutive transmission, including a final check code for verifying an error in the entire transmission data in the final frame , and the transmission data is transmitted a plurality of times perform consecutive transmission , a transmission device, and the transmission data is received a plurality of times without error , and a receiving device that combines frames to generate normal transmission data and the receiving device includes an error data detection unit that detects whether there is an error in the received transmission data based on the final check code, a data comparison and replacement unit that extracts data of normal frames from a plurality of consecutively transmitted transmission data with errors and generates synthesized data, and a data decoding unit that decodes the input data. When there is no error in the first transmission data, the error data detection unit transfers the first transmission data to the data decoding unit. When there is an error in the first transmission data and no error in the second transmission data, the error data detection unit transfers the second transmission data to the data decoding unit. When there are errors in both the first transmission data and the second transmission data, the error data detection unit transfers the first transmission data and the second transmission data to the data comparison and replacement unit. The data comparison and replacement unit incorporates data of frames without error into the synthesized data by determining the frame check code in each frame of the first transmission data, determines the correctness of frames with errors in the first transmission data using the frame check code of the second transmission data, and incorporates the frames into the synthesized data if they are normal. When data of all frames in the transmission data are incorporated into the synthesized data, the data comparison and replacement unit outputs the synthesized data to the data decoding unit , characterized by this

[0024] Further, in the present invention in the above wireless transmission system, the transmission device assigns a sequence number to each frame in the transmission data, and the receiving device discriminates the sequence number and recognizes the transmission data composed of frames related by the sequence number

[0025] Further, in the present invention in the above wireless transmission system, the error data detection unit of the receiving device by the data comparison and replacement unit When normal transmission data cannot be generated even if error-free frames are selected, a retransmission request for the frames insufficient for the generation is made to the transmission device, the transmission device retransmits the frames to the receiving device in response to the frame retransmission request, and the receiving device generates normal transmission data using the retransmitted frames

[0026] Further, in the present invention in the above wireless transmission system, the receiving device makes a retransmission request to the transmission device for frames with errors in the transmission data received first, the transmission device retransmits the frames to the receiving device a plurality of times in response to the frame retransmission request, and the receiving device generates normal transmission data using the frames retransmitted a plurality of times

Advantages of the Invention

[0027] According to the present invention, there is provided a wireless transmission system that performs data transmission using wireless communication. When the transmission data to be transmitted spans multiple frames, an error check of the data within each frame is performed within each frame frame including a check code while performing consecutive transmission, including a final check code for verifying an error in the entire transmission data in the final frame , and the transmission data is transmitted multiple times perform consecutive transmission A transmission device that transmits the transmission data multiple times without error A receiving device that receives the transmission data multiple times and combines the frames to generate normal transmission data A receiving device includes an error data detection unit that detects whether there is an error in the transmitted data received based on the final check code, a data comparison and replacement unit that extracts data of a normal frame from a plurality of consecutively transmitted transmitted data with errors and generates synthesized data, and a data decoding unit that decodes the input data. When there is no error in the first transmitted data, the error data detection unit transfers the first transmitted data to the data decoding unit. When there is an error in the first transmitted data and no error in the second transmitted data, the error data detection unit transfers the second transmitted data to the data decoding unit. When there are errors in both the first transmitted data and the second transmitted data, the error data detection unit transfers the first transmitted data and the second transmitted data to the data comparison and replacement unit. The data comparison and replacement unit incorporates data of frames without errors determined by the frame check code in each frame of the first transmitted data into the synthesized data, determines the correctness of frames with errors in the first transmitted data using the frame check code of the second transmitted data, and incorporates the frames into the synthesized data if they are normal. When data of all frames in the transmitted data are incorporated into the synthesized data, the synthesized data is output to the data decoding unit. Since it is a wireless transmission system, it is possible to determine whether each frame is normal or in error. Even if all the data received multiple times is in error, normal transmission data can be generated by combining the normal frames among them, and there is an effect of improving the reception rate.

[0028] Further, according to the present invention, the transmission device assigns a sequence number to each frame in the transmission data, and the receiving device discriminates the sequence number and recognizes the transmission data composed of frames related by the sequence number. Since it is the above wireless transmission system, even if all the leading frames of the transmission data received multiple times are in error, it is possible to specify the data from the sequence numbers of other frames and make a retransmission request, increasing the possibility of generating normal transmission data and having an effect of improving the reception rate.

[0029] Further, according to the present invention, the Error data detection unit of the receiving device In the data comparison and replacement unit When normal transmission data cannot be generated even by selecting error-free frames, a retransmission request for the frames lacking for the generation is made to the transmission device. The transmission device retransmits the frames to the receiving device in response to the frame retransmission request, and the receiving device uses the retransmitted frames to generate normal transmission data. Since it is the above wireless transmission system, retransmission can be performed in units of frames instead of the entire data, shortening the transmission time associated with retransmission and reducing the possibility of errors occurring, and having an effect of improving the reception rate.

[0030] Further, according to the present invention, the receiving device requests the transmitting device to retransmit a frame with an error in the initially received transmission data. The transmitting device retransmits the frame to the receiving device a plurality of times in response to the frame retransmission request. Since the receiving device is the above wireless transmission system that generates normal transmission data using the frames retransmitted a plurality of times, by making a retransmission request on a frame-by-frame basis without waiting for the transmission data transmitted later, there is an effect that a normal frame can be quickly acquired and normal transmission data can be generated in a short time.

Brief Description of Drawings

[0031]

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Embodiments for Carrying Out the Invention

[0032] Embodiments of the present invention will be described with reference to the drawings. [Overview of Embodiment] The wireless transmission system (this wireless transmission system) according to an embodiment of the present invention is such that when the transmission data to be transmitted by the transmitting device spans multiple frames, the transmitting device includes a check code for checking errors in the data within each frame in each frame, and transmits the transmission data spanning multiple frames multiple times (consecutive transmission). The receiving device receives the transmission data multiple times, and if there is an error in the transmission data, it selects a frame without error by determining the check code among the transmission data received multiple times, and combines the selected frames to generate normal transmission data. Even if an error occurs in each of the consecutively transmitted transmission data, the possibility of obtaining normal transmission data can be increased, and the reception rate can be improved.

[0033] In addition, in this wireless transmission system, the transmitting device attaches the same sequence number to each frame in the transmission data and transmits it, and the receiving device identifies related frames based on the sequence number and recognizes the transmission data spanning multiple frames. When receiving the transmission data spanning multiple frames multiple times, each transmission data can be clearly identified. In particular, even if there is a loss in the leading frame among all the transmission data received multiple times, the incorrect transmission data can be identified based on the sequence number, and frames without error can be used for combination.

[0034] Furthermore, in this wireless transmission system, when the receiving device cannot generate normal transmission data even after selecting a frame without error, it requests retransmission for the missing frames in frame units, and the transmitting device retransmits the specified frames. The transmission time associated with the retransmission can be shortened, and the probability of an error occurring can be reduced.

[0035] [Configuration of This Wireless Transmission System] Since the basic configuration of this wireless transmission system is the same as the wireless transmission system shown in FIG. 7, the same reference numerals will be used for description. However, for the base station device 3 and the mobile station device 4 that perform wireless communication, the configuration and the processing during transmission and reception are different from the conventional ones. Also, as will be described later, the line control device 2 may also perform new processing when receiving from the base station device 3.

[0036] In this wireless transmission system, the data length of the transmission data is long. When the transmission device transmits (continuous transmission) multiple times across a plurality of frames, and when there is an error in the transmission data received multiple times by the receiving device, the operation is characterized by extracting and combining error-free frames from the received transmission data to generate synthesized data.

[0037] [Configuration of the base station device according to the embodiment: FIG. 1] The configuration of the base station device of this wireless transmission system will be described with reference to FIG. 1. FIG. 1 is an explanatory diagram showing the schematic configuration of the base station device. Here, the base station device 3 is shown as an example of the transmission / reception device of this wireless transmission system, but the mobile station device 4 also has the same constituent parts. That is, the base station device 3 and the mobile station device 4 have the configurations of both the transmission device and the reception device described in the claims. Note that in FIG. 1, only the parts related to the present invention are shown, and other constituent parts are the same as those in the prior art and are thus omitted.

[0038] As shown in FIG. 1, the base station device 3 of this wireless transmission system includes a wireless reception unit 31, an error data detection unit 32, a data decoding unit 33, a data comparison and replacement unit 34, a transmission processing unit 35, and a wireless transmission unit 36. Among these, the wireless reception unit 31, the data decoding unit 33, and the wireless transmission unit 36 have the same configurations and operations as those in the prior art. The wireless reception unit 31 demodulates the reception signal received by the antenna. Also, the data decoding unit 33 decodes the input data and outputs the transmission data.

[0039] The error data detection unit 32 detects whether there is an error in the demodulated reception data. Specifically, when transmission data spanning multiple frames is input, the error data detection unit 32 first holds it until the final frame is input, and checks whether there is an error in the entire transmission data based on the check code of the final frame. If there is no error, the entire transmission data is transferred to the data decoding unit 33. Also, when there is an error in the check code of the final frame and the same transmission data has not already been output to the data decoding unit 33, the transmission data is transferred to the data comparison and replacement unit 34.

[0040] Furthermore, when error-free combined data is input from the data comparison and replacement unit 34, the error data detection unit 32 outputs the combined data to the data decoding unit 33. Moreover, when an instruction for retransmission request is input from the data comparison and replacement unit 34, the error data detection unit 32 outputs the signal type and the sequence number of the received data to the transmission processing unit 35 as information for specifying the transmission data for which retransmission is requested. The processing of the error data detection unit 32 will be described later.

[0041] The data comparison and replacement unit 34 extracts and combines the data of normal frames from a plurality of consecutive error-containing transmission data, generates error-free combined data, and outputs it to the data decoding unit 33 via the error data detection unit 32. At that time, based on the sequence number in each frame, the data comparison and replacement unit 34 recognizes that even if the plurality of frames span multiple frames, the plurality of frames are related to each other and are one transmission data. Extracting and combining normal parts from a plurality of transmission data is sometimes referred to as data interpolation.

[0042] Specifically, when error-containing transmission data is input, the data comparison and replacement unit 34 sequentially checks whether there is an error in the transmission data from the first frame using the frame check code described later. In the case of double transmission, the data comparison and replacement unit 34 incorporates the data of the frame determined to be error-free in the first transmission data into the combined data.

[0043] Then, when the data comparison and replacement unit 34 recognizes the second transmission data based on the sequence number, for the frames that could not be obtained with the first transmission data, it determines the correctness using the frame check code of the second transmission data, and if it is normal, it incorporates it into the synthesized data. When the data of all frames has been obtained, the synthesized data is output to the data decoding unit 33.

[0044] Also, when there is a frame that still cannot be obtained even after interpolation with the second transmission data, the data comparison and replacement unit 34 outputs an instruction for a retransmission request to the error data detection unit 32. At this time, as a feature of this wireless transmission system, the data comparison and replacement unit 34 makes a retransmission request in units of frames and makes a retransmission request only for the necessary frames.

[0045] Thus, in this wireless transmission system, even if the leading frame is incorrect in all of the multiple input transmission data, the data comparison and replacement unit 34 can identify the transmission data by the sequence number and can output a retransmission request for the leading frame. The processing of the data comparison and replacement unit 34 will be described later.

[0046] When the transmission processing unit 35 receives a retransmission request from the error data detection unit 32, it generates a retransmission request message for the transmission data and outputs it to the wireless transmission unit 36. Also, when the transmission processing unit 35 of this wireless transmission system transmits transmission data that spans multiple input frames, at the time of generating a message, it attaches the same sequence number to each frame and includes a frame check code for detecting the presence or absence of an error in each frame on the receiving side and then transmits it. The wireless transmission unit 36 modulates the message for transmission and transmits it as a wireless signal via the antenna.

[0047] [Example of bit allocation in this wireless transmission system: Figure 2] Next, an example of bit allocation for FACCH in this wireless transmission system will be described with reference to FIG. 2. FIG. 2 is an explanatory diagram showing an example of bit allocation in this wireless transmission system. As shown in FIG. 2, it shows transmission data spanning five frames from the first frame 401-1 to the last frame 401-5. As a feature of this wireless transmission system, a sequence number (denoted as "SN" in the figure) is stored in the additional signal type stored in octet 2 and octet 3. In addition, the signal configuration information and transmission data of each frame, and the check code of the last frame are stored in the same manner as in the conventional wireless transmission system shown in FIGS. 8 and 9.

[0048] The sequence number is a characteristic part of this wireless transmission system and is a number for identifying transmission data transmitted from a transmitting device. Specifically, the sequence number is a number inserted when the transmitting device transmits transmission data spanning multiple frames. When one data is divided and stored in multiple frames, the same sequence number is attached to each frame. When the same data is continuously transmitted, the sequence number is also the same number.

[0049] Then, in the first transmission during continuous transmission, the transmitting device transmits the first frame 401-1 to the last frame 401-5 of the transmission data as transmission frames 1 to 5 (dotted line), and in the second transmission, it transmits the same transmission data as transmission frames 6 to 10 (two-dot chain line).

[0050] Thereby, in the receiving device, it can be easily recognized that a series of data transmitted across multiple frames is one data, and that data continuously transmitted and received multiple times is the same data. In particular, when there is an error in the first frame, the data can be specified and a retransmission request for each frame can be made, improving the possibility of obtaining normal transmission data.

[0051] Furthermore, in this wireless transmission system, a frame check code for checking whether there is an error in the data of each frame is stored. As shown in FIG. 2, for the leading frame 401-1 to the intermediate frame 401-4, the frame check code is stored in octet 13, and for the final frame 401-5, the frame check code is stored in octet 12.

[0052] Thereby, in the receiving device, even for data determined to have an error based on the check code of the final frame, it is possible to determine the presence or absence of an error for each received frame, select frames without errors and incorporate them into the synthesized data, and increase the possibility of generating error-free synthesized data using a plurality of transmission data with errors.

[0053] [Example of data interpolation by consecutive transmission (when interpolation is successful): FIG. 3] Next, an example of data interpolation in the data comparison and replacement unit 34 of the receiving device will be described with reference to FIG. 3. FIG. 3 is an explanatory diagram showing an example of data interpolation by consecutive transmission (when interpolation is successful). As shown in FIG. 3, in the data comparison and replacement unit 34, when the first transmission data (consecutive transmission data 1) and the second transmission data (consecutive transmission data 2) with the same sequence number are input from the error data detection unit 32, for each consecutive transmission data, the presence or absence of an error is determined for each frame using the frame check code. Then, the data of the frames received normally is incorporated into the synthesized data. The synthesized data is generated corresponding to the sequence number.

[0054] In the example of FIG. 3, in the consecutive transmission data 1, since the leading frame, intermediate frame 2, and intermediate frame 3 are normal, the data comparison and replacement unit 34 incorporates the data of these frames into the synthesized data. However, since the intermediate frame 1 and the final frame have errors, they are not incorporated into the synthesized data.

[0055] Therefore, the data comparison and replacement unit 34 checks the frame check codes of the intermediate frame 1 and the final frame of the continuous transmission data 2. If they are normal, it captures the intermediate frame 1 and the final frame of the continuous transmission data 2 into the composite data. As a result, the transmission data is the one where normal composite data has been generated. The data comparison and replacement unit 34 transfers the composite data to the data decoding unit 33 via the error data detection unit 32, and the composite data is decoded.

[0056] [Example of data interpolation by continuous transmission (in case of interpolation failure): Figure 4] Next, the case where normal data cannot be obtained even when the data comparison and replacement unit 34 performs data interpolation (in case of interpolation failure) will be described with reference to FIG. 4. FIG. 4 is an explanatory diagram showing an example of data interpolation by continuous transmission (in case of interpolation failure). As shown in FIG. 4, in the continuous transmission data 1, when the head frame and the intermediate frames 2 and 3 are normal and the intermediate frame 1 and the final frame are in error, the data comparison and replacement unit 34 captures the data of the head frame and the intermediate frames 2 and 3 that are normal into the composite data. Then, based on the frame check code of the continuous transmission data 2, the correctness of each frame is determined.

[0057] As a result of the check, when it is determined that the intermediate frame 2 and the final frame are normal and the head frame and the intermediate frames 1 and 3 are in error, the data comparison and replacement unit 34 captures the data of the final frame that is normal into the composite data. However, since the intermediate frame 1 is in error in both the continuous transmission data 1 and 2, it cannot be captured into the composite data, and the data cannot be decoded.

[0058] Therefore, the data comparison and replacement unit 34 outputs an instruction for retransmission request of the intermediate frame 1 to the error data detection unit 32. Upon receiving the retransmission request instruction, the error data detection unit 32 attaches a sequence number for identifying the transmission data and instructs the transmission processing unit 35 to retransmit. Upon receiving the instruction, the transmission processing unit 35 transmits the retransmission request of the transmission data to the transmitting device (transmitting apparatus) of the transmission source.

[0059] When the transmission device receives a retransmission request, it retransmits the specified frame of the transmission data. At this time, the transmission device attaches the same sequence number as the original transmission data to the frame to be retransmitted. As a result, the data comparison and replacement unit 34 of the receiving device recognizes which data is being retransmitted, checks normal / error for each frame of the retransmitted data, and if it is normal, it can be used for generating composite data.

[0060] In this way, in this wireless transmission system, at the time of retransmission, it is possible to retransmit only the necessary frames instead of the entire long data spanning multiple frames, shortening the transmission time associated with retransmission, reducing the probability of transmission errors occurring, and improving the reception rate.

[0061] In particular, conventionally, when all the leading frames were in error even when consecutive transmission was performed, it was necessary to retransmit all the transmission data. However, in this wireless transmission system, the transmission data can be specified by the sequence number. After capturing the frames that were normal into the composite data and requesting and obtaining the retransmission of the leading frame, decoding becomes possible, and the transmission efficiency and reception rate can be improved.

[0062] Also, as another operation, for example, when the middle frame 1 and the last frame of the consecutive transmission data 1 are in error, the data comparison and replacement unit 34 may output an instruction for retransmission request so as to transmit the two frames without waiting for the check of the consecutive transmission data 2. In the retransmission request, the retransmission from the transmission device may be configured to be performed by consecutive transmission or may be performed by a single transmission. Also, the retransmission request itself from the receiving device may be performed by consecutive transmission or may be regarded as a single transmission.

[0063] [Processing of error data detection unit 32: Figure 5] Next, the processing in the error data detection unit 32 when receiving transmission data will be described with reference to FIG. 5. FIG. 5 is a flowchart showing the processing of the error data detection unit. Here, a case where transmission data is transmitted from the transmission side in consecutive transmissions (for example, two consecutive transmissions) will be described as an example. As shown in FIG. 5, when transmission data is input from the wireless reception unit 31 to the error data detection unit 32 (S11), the error data detection unit 32 checks the sequence number (S12), and determines whether the transmission data is normal based on the check code of the final frame (S13).

[0064] In process S13, if the transmission data is normal (Yes), the error data detection unit 32 outputs the transmission data to the data decoding unit 33 (S14) and ends the process. If transmission data with the same sequence number has already been determined to be normal and output to the data decoding unit 33, the transmission data may not be output to the data decoding unit 33 and may be discarded. That is, if the data of consecutive transmission 1 is normal, the data of consecutive transmission 2 may be discarded without being decoded.

[0065] Also, in process S13, if the transmission data is not normal (No), the error data detection unit 32 determines whether transmission data with the same sequence number has already been determined to be normal (S15). If transmission data with the same sequence number has not yet been determined to be normal (No), the error data detection unit 32 outputs the transmission data to the data comparison and replacement unit 34 (S16) and ends the process.

[0066] Also, in process S15, if transmission data with the same sequence number has already been determined to be normal (Yes), the error data detection unit 32 discards the transmission data without outputting it to the data comparison and replacement unit 34 (S20) and ends the process.

[0067] That is, the transmission data of consecutive transmission 1 is output to the data decoding unit 33 if it is normal, and output to the comparison and replacement unit 34 if there is an error. On the other hand, the transmission data of continuous transmission 2 is output to the data decoding unit 33 only when the data of continuous transmission 1 is in error if it is normal. At this time, the error data detection unit 32 may output an instruction to the data comparison and replacement unit 34 to discard the transmission data of continuous transmission 1 with the same sequence number that has already been input. In addition, even if the transmission data of continuous transmission 2 is normal, it may be discarded if the data of continuous transmission 1 is normal. Also, if the transmission data of continuous transmission 2 is in error, it is output to the comparison and replacement unit 34 only when the transmission data of continuous transmission 1 is in error, and is discarded when the transmission data of continuous transmission 1 is normal.

[0068] In addition, when the transmission data that is not continuous transmission is in error, the error data detection unit 32 discards the transmission data without outputting it to the data comparison and replacement unit 34, and outputs a retransmission request for the entire data to the transmission processing unit 35. In this way, the processing of the error data detection unit 32 is performed.

[0069] [Processing of data comparison and replacement unit 34: Figure 6] Next, the processing of the data comparison and replacement unit 34 will be described with reference to FIG. 6. FIG. 6 is a flowchart showing the processing of the data comparison and replacement unit. As shown in FIG. 6, when the data comparison and replacement unit 34 receives error-prone continuous transmission data from the error data detection unit 32 (S21), it checks the sequence number (S22). Here, the data comparison and replacement unit 34 counts the number of continuous transmission data with the same sequence number.

[0070] Then, the data comparison and replacement unit 34 determines normal / error for each frame of the continuous transmission data using the frame check code (S23), and takes in the data of the normal frame as the data of the composite data of the corresponding sequence number (S24).

[0071] Then, the data comparison and replacement unit 34 determines whether all frames of data have been captured into the synthesized data (S25). If the capture is completed (YES), the synthesized data is output to the data decoding unit 33 via the error data detection unit 32.

[0072] In process S25, if the capture is not completed (No), the data comparison and replacement unit 34 determines whether all consecutive data has been checked (two in the case of two consecutive transmissions) (S27). If there is still consecutive data remaining (No), the process returns to S21 to wait for the input of the next consecutive data.

[0073] Incidentally, at this time, a limit may be set for the waiting time of consecutive data with the same sequence number. If a timeout occurs, the data comparison and replacement unit 34 may discard the consecutive data and end the process. As a result, even if the data of consecutive transmission 1 is in error and input to the data comparison and replacement unit 34, if the data of consecutive transmission 2 is normal and output to the data demodulation unit 33, the process for the sequence number can be ended. Alternatively, in the error data detection unit 32, when the data of consecutive transmission 1 with the same sequence number is in error and the data of consecutive transmission 2 is normal, the error data detection unit 32 may instruct the data comparison and replacement unit 34 to discard the consecutive data of the sequence number.

[0074] Also, in process S27, if all consecutive data has been checked (YES), the data comparison and replacement unit 34 outputs an instruction for a retransmission request for the missing frames (frames that have become errors in all consecutive data) to the error data detection unit 32 (S28) and ends the process. In this way, the processing of the data comparison and replacement unit 34 is performed.

[0075] [Effects of the Embodiment] According to this wireless transmission system, when the transmission data to be transmitted by the transmission device spans multiple frames, the transmission device includes a check code for checking the error of the data in each frame in each frame, and transmits the transmission data spanning multiple frames multiple times (consecutive transmission). When the base station device 3 or the mobile station device 4, which is the receiving device, receives the transmission data multiple times and the error data detection unit 32 detects that there is an error in the transmission data, it outputs to the data comparison replacement unit 34. The data comparison replacement unit 34 selects frames without errors by determining the check code among the transmission data received multiple times, combines the selected frames, and generates normal transmission data. Even if errors occur in each of the consecutively transmitted transmission data, the possibility of obtaining normal transmission data can be increased, and there is an effect of improving the reception rate.

[0076] Also, according to this wireless transmission system, the transmission device attaches the same sequence number to each frame in the transmission data and transmits it. The receiving device identifies related frames based on the sequence number and recognizes the transmission data spanning multiple frames. When there is an error in the received transmission data, in the data comparison replacement unit 34, frames without errors are selected and combined from the transmission data to which the same sequence number is assigned, and normal transmission data corresponding to the sequence number is generated. When receiving transmission data spanning multiple frames multiple times, each transmission data can be clearly identified. In particular, even if a loss occurs in the leading frame among all the transmission data received multiple times, the transmission data can be identified by the sequence number, and the possibility of decoding the transmission data can be increased by making a retransmission request for the leading frame.

Industrial Applicability

[0077] The present invention is suitable for a wireless transmission system that can easily identify that the data is the same on the receiving side and combine normal data when transmitting transmission data spanning multiple frames multiple times consecutively, and can improve the reception rate.

Explanation of Signs

[0078] 1... Instruction console, 2... Line control device, 3... Base station device, 4... Mobile station device, 31... Radio reception unit, 32... Error data detection unit, 33... Data decoding unit, 34... Data comparison and replacement unit, 35... Transmission processing unit, 36... Radio transmission unit 301, 401... FACCH

Claims

1. A wireless transmission system that performs data transmission using wireless communication, when the transmission data to be transmitted spans multiple frames, includes a frame check code for checking errors in the data within each frame, and includes a final check code for checking errors in the entire transmission data in the final frame, and performs consecutive transmission of transmitting the transmission data multiple times; a receiving device that receives the transmission data multiple times and combines error-free frames to generate normal transmission data, and has: The receiving device includes an error data detection unit that detects whether there is an error in the received transmission data based on the final check code, a data comparison and replacement unit that extracts data of normal frames from a plurality of consecutively transmitted transmission data with errors and generates synthetic data, and a data decoding unit that decodes the input data. When there is no error in the first transmission of transmission data, the error data detection unit transfers the first transmission of transmission data to the data decoding unit. When there is an error in the first transmission of transmission data and no error in the second transmission of transmission data, the error data detection unit transfers the second transmission of transmission data to the data decoding unit. When there are errors in both the first and second transmissions of transmission data, the error data detection unit transfers the first and second transmissions of transmission data to the data comparison and replacement unit. The data comparison and replacement unit incorporates data of frames without errors into synthetic data by determining frame check codes in each frame of the first transmission of transmission data. For frames with errors in the first transmission of transmission data, the data comparison and replacement unit determines correctness using the frame check code of the second transmission of transmission data and incorporates it into the synthetic data if it is normal. When data of all frames in the transmission data is incorporated into the synthetic data, the data comparison and replacement unit outputs the synthetic data to the data decoding unit. A wireless transmission system characterized by this.

2. The transmission device assigns a sequence number to each frame in the transmission data. The receiving device discriminates the sequence number and recognizes transmission data composed of frames related by the sequence number. The wireless transmission system according to Claim 1, characterized by this.

3. When the error data detection unit of the receiving device cannot generate normal transmission data even if a frame without errors is selected by the data comparison and replacement unit, the receiving device requests the transmitting device to retransmit the frames that are insufficient for the generation. The transmitting device retransmits the frame to the receiving device in response to the retransmission request of the frame. The wireless transmission system according to claim 1 or 2, wherein the receiving device generates normal transmission data using the retransmitted frame.

4. The receiving device requests the transmitting device to retransmit frames with errors in the initially received transmission data. The transmitting device retransmits the frame to the receiving device multiple times in response to the retransmission request of the frame. The wireless transmission system according to claim 1 or 2, wherein the receiving device generates normal transmission data using the frames retransmitted multiple times.

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