TW424365B - Transmission system with improved reconstruction of missing parts - Google Patents

Abstract

In a transmission system a signal to be transmitted by a first node (2) is applied to an encoder (8) and is transmitted by a transmitter (10) to a second node (6). In the second node (6) the signal from the transmission medium (4) is received by the receiver (12) and passed to a selector (18), directly and via an interpolator (14). By delaying the decoding of the signal in the case transmission errors occur, which lead to missing frames, it becomes possible to complete the missing frames by interpolation.

Description

^^ 4365

V. Description of the invention (l) ^ The present invention has a transmission system with M. The system includes—a first node having an encoder from the input signal to the source signal of the encoding signal, and the first node further includes a node for transmitting through the transmission medium. The transmission of the encoded signal to the second node. The second node includes a reconstruction device that obtains a reconstruction signal from the encoded signal. The present invention also relates to a node, a reconstruction device, and a reconstruction method. The preamble on which the transmission system is based is known from US Patent No. 4,907,2U. This type of transmission system is used for source signals transmitted through transmission media with limited transmission capacity, or applications that must be stored in storage media with limited storage capacity. Examples of this type of application are the transmission of voice signals over the Internet. The transmission of voice signals from the mobile phone to the base station and back, and the voice signals are stored on a CD-ROM. In a solid-state memory or on a hard disk β In order to reduce the bit rate of the signal to be transmitted or stored, a source encoder is used which can obtain an encoded signal from the input signal. This source encoder can operate according to different operating principles. Examples of such operating principles are PCM, DPCM, RPE, CELP, and conversion encryption (sub-frequency encryption, DCT). In the case of unstable transmission media such as mobile wireless channels, it may happen that the second node does not receive part of the encoded signal correctly. To maintain the quality of the decoded signal, the second node contains an interpolator that is used to complete the reconstruction of the missing part of the signal. The above-mentioned U.S. patent discloses a method that uses an interpolation method that surrounds the missing part to obtain a good quality completed missing part. A disadvantage of the transmission system according to this U.S. patent is that the decoding delay is increased due to interpolation processing.

424365

Preamble for reducing average delay value V. Description of the invention (2) The object of the present invention is to provide a transmission system based on availability. In order to obtain this purpose, 'the quality of the received coded signal according to the transmission system of the present invention meets this': used to provide the reconstruction signal immediately, if the quality of the received coded signal is accepted if the' Bei reconstruction device is in good condition. Without certain quality standards, the reconstruction device is used to provide a signal after the reconstruction delay. The basis of the present invention is to recognize the possibility of reconstructing the source signal in the case of a bad signal to improve the increase in the reconstruction delay in the case of the bad signal. Increasing the reconstruction delay allows interpolation to be used to complete the missing part of the decoded signal, or allows the first node to retransmit the missing part of the encoded signal. It can be observed that in order to make the signal delay not greater than the 'reconstruction delay required in the case of a good signal, it will only increase in the case of a bad signal. 3 The specific embodiment of the invention is characterized in that its quality standard is the completion of the received encoded signal And the reconstruction device includes a completion device for completing the reconstruction signal if the received signal is incomplete. According to this specific embodiment, if a complete signal is received within a known immediate time, the source signal is directly reconstructed. If a part of the decoded signal is missing, it will increase the reconstruction delay 'to allow interpolation or to require retransmission to complete the missing part of the encoded signal. It can be observed that interpolation is not required to be performed on the encoded signal, but it may be necessary to perform interpolation on the decoded signal frame. A further specific embodiment of the present invention is characterized in that the reconstruction device will increase the reconstruction delay according to the quality of the received encoded signal = using the increased reconstruction delay to reduce the quality of the received encoded signal ’

424365

V. Description of the invention (3) Partially followed by ~ In the test, it is easy to get better source signal reconstruction. For example, if a large encoded signal is lost, more extra time is required for the interpolation method or the node to retransmit to complete the signal. It is still a further specific embodiment of the present invention that the reconstruction device is used to reduce the reconstruction delay when the reconstruction signal is lacking. If it is determined that the lack of a source signal reduces the reconstruction delay, a reconstruction delay that is not more than absolutely necessary to obtain a good source signal reconstruction can be obtained. It is still a further specific embodiment of the present invention that the source and signal include voice signals, and the second node includes a comfort noise introduction device for introducing comfort utterances to the extent that the received encoded signals will improve in quality. ’By using the low-quality received encoding signal to introduce more comfortable sounds, the attenuation of the quality of the wheel will result in a sound channel similar to the analog transmission system that users are used to. It is still a further specific embodiment of the present invention that the transmission system includes a full-duplex voice transmission system, and a side tone importing device is included in the second node to introduce a side tone that can reduce the degree of reconstruction delay. A subsequent adverse effect of increasing the decoding delay is echo plus enhancement. The source of the echo is the introduction of sidetones, which is very common in telephone systems. The introduction of sidetones is to provide users with sound feedback for certain transmitted audio signals. Decreasing the level of sidetone signals reduces the adverse effects of echo. The nausea is reduced at this time. The present invention will be described with reference to the following formulas, respectively: Fig. 1 is a first specific embodiment of a transmission system according to the present invention, in which the received signal is completed using interpolation.

424365 V. Description of the invention (4) ----- Fig. 2 is a detailed diagram of the interpolator 14 according to Fig. 1. FIG. 3 is a detailed configuration diagram for performing the functions of the interpolator 14 and the selector 8. FIG. 4 is a timing diagram of the received signal reconstruction in the wheel transmission system according to FIG. 1. FIG. 5 is a detailed diagram of the error detector 16. Fig. 6 shows a second specific embodiment of the present invention, which uses re-transmission to complete the received signal. FIG. 7 is a first possible time chart of reconstruction of a received signal in the transmission system according to FIG. 6. FIG. FIG. 8 is a second possible time chart of reconstruction of a received signal in the wheel transfer system according to FIG. 6. FIG. 9 is an embodiment of an audio processing function in a second node according to the present invention. 1. In the transmission system according to FIG. 1, the signals of all the transmissions of node 2 will be supplied to the input of the source encoder 8, and the encoded signals on the output of the source encoder 8 will be presented as a frame.二 node 6. The operation of the transmitter 10 includes channel encryption and modulation β. In the second node 6, the receiver 2 processes signals from the transmission medium 4. The operation of the receiver 12 includes demodulation and channel encryption. The reconstruction device according to the concept of the present invention includes a configuration device 13 and a decoder 20. The received encoded signal is now displayed on the output of the receiver ^, and the received node signal is sent to a quality determination device 6 which determines the quality of the received encoded signal. For example, the product determination device 16 may include a decoder of a block code such as a Reed-Som code. In this case, the quality criterion may be a received coded signal with or without uncorrectable errors or not. a,

C: \ Program Files \ Patent \ 55037. Ptd page 8 mi 424365 5. Description of the invention (5) If it meets the quality standards (no unreachable '', renewed errors) will complete the current connection

Receive the frame of the encoded signal. If the ^^^ and He's other frames are also completed, the received encoded signal Jigulang & ^ ^ will be passed to the decoder 20 through the selector 18. # 择 器 18 will receive the recognition from the quality determination device > ^ Select the appropriate control signal and pass the received encoded signal directly to the decoder 2. The signal is reconstructed on the output of "㈣". If the quality standard is not met (there is an uncorrectable error), the selector 18 is instructed to send the previous frame to the decoder 20 again. It further instructs the interpolator 14 to complete the missing frame from the frame surrounding the incorrectly received frame. After performing the interpolation, the interpolated frame is passed to the decoder. Because the interpolation method is performed, the decoding of the interpolation frame and the prediction of the source of the reconstructed signal are delayed. Obviously, it is impossible to re-select the undelayed received decoded signal to be transmitted to the encoder, because this will cause noticeable disturbances', which can only be changed back to undelayed reconstruction after a period of silence. If the quality detecting device 16 detects such a quiet time, the selector 8 will instruct to pass the output signal of the receiver 12 directly to the decoder 20 again. In the interpolator 14, the wheel-out signal of the receiver 12 is supplied to the stepwise connection of the delay element 22 and the delay element 24. The delay value of these delay elements is equal to one frame time. The interpolator 26 is used to calculate interpolated frames from the frames which are rounded in from the delay element 26 and output from the delay element 24. If the signal to be transmitted is a voice signal, the encoded signal can be based on linear prediction. The frame contains representatives of many predictive coefficients and representatives of the execution signal. The execution signal is sent to a synthesis process with parameters derived from predictive coefficients.

I circle C: \ Program Files \ Patent \ 55037. Ptd page 9 α b b 5. Description of invention ¢ 6)-Filter. If the frame i -1 is received incorrectly, the predictive coefficient Γ-1 can be calculated according to the following formula: aK [i ^ i] = Mh | ± ^ Ki! I (A) .. The interpolated predictive coefficient can be, For example, Γ logarithmic region ratio "," linear spectral pair "and inverse sine function of reflection coefficient. Those skilled in the art are familiar with the representation of these predictive coefficients. Because the execution signal varies from frame to frame, the interpolated execution signal will differ from the original signal. Therefore, the execution signal is normally not interpolated, but the previous frame value is used. If the frame is received incorrectly, the selector 28 is instructed to pass the turn of the interpolator 26 to the decoder 20. If the frame is received correctly, a delayed reception inscription signal that is more than one frame time available on the output of the delay element 22 is passed to the decoder 20. ° FIG. 3 shows a configuration combining the functions of the interpolator 14 and the selector 18. Furthermore, this configuration device can provide one or two missing frames by interpolation. The input signal of this arrangement is sent to the stepped connection of the delay element 32 and the delay element 34. The configuration device receives three control signals from the quality determination device 16. The first control signal £ RR indicates that the frame on the input of the configuration device is wrong. 'The second control signal⑽ ^ indicates that the configuration device is delayed.' The third signal INTERP〇UTE # indicates the number of frames to be completed by interpolation. 70

C: \ ProgramFiles \ Patent \ 55037_ptd Page 10 4 2 4 3 6 5 V. Description of the invention (7) One by one " · If all the frames are received incorrectly, the value of the signal scale is false (false), The value of the signal DELAY is equal to 0, and the value of the signal INTERPOLATE # is also equal to 0. In this case, the selector 40 is instructed to pass the input signal of the delay element 30 to the decoder 20. This is shown in frames 1, 2 and 3 of the chevron 50 and 52 in FIG. In the case of a frame receiving error, the signal ERROR will become equal to 1 °. If the number of errors indicated by ERR is less than or equal to the value of DELAY, the selector will pass the same output signal to the decoder 20. Because the number of errors (1) is greater than the value of DELAY in this case, the logic circuit 42 will instruct the selector 40 to render the previous frame on the output again, such as frame 3, until an interpolated frame 3 is available. This can be seen in the figure 50. This figure shows that the frame 3 will be sent to the demeater again. When you receive the first correct frame, you can know how many frames are missing and how many frames to perform interpolation. The signal iNTERp〇LATE # will display the number of frames. At the same time, the value of DELAY will be set to the maximum function of the current DELAY value and the number of missing frames. Only frame 4 between frames 3 and 5 is missing in figure 30. Once frame 5 is received correctly, the signals DELAY and INTERPOLATE # will be set to 1. This will cause the selector 36 to pass the output signal of the delay element 32 (that is, frame 3) to the first input of the interpolator 38 and the second component of the interpolator 38 can obtain the output signal of the delay element (that is, Yes frame 5). Once the interpolation method is completed, the selector 40 will pass the output signal of the interpolator 38 to the canceller 20. This can be seen in figure 50, where the interpolated frame 4 is passed after the second phase of frame 3.

C: \ ProgramFiles \ Patent \ 55037.ptd Page 11 424365 V. Description of the invention (8) The value 1 of the signal DELAY will cause the selector 4 to pass the output of the delay element 30 to the frame 4 'after the interpolation. The input of the decoder 20. Because the stage frame 5 is obtained on the output of the delay element, the frame 5 is passed to the decoder 20 after the frame 4 ', as seen in the figure 50. It can be seen from the graph 50 that the delay will increase after a pass error occurs. If the next signal error occurs, there will be no interruption because the interpolation results will be presented in real time. And because the value of DELAY remains the same, the subsequent frame to be passed to the decoder 20 is still taken from the output of the delay element 30. If two frames from the input signal are missing, as shown in Figure 52, where frames 8 and 9 are missing, interpolation of more than two frames will be performed. On the detection of error receiving frame 8, the signal ERR will be set to 1. Because the number of errors and the value of DELAY are both equal to i, the selector 40 indicates that the output signal of the delay element 30 (ie, frame 7) is still passed to the decoder 2o. When the next frame 9 also causes an error ', the value of ERR will increase to two. Because the number of error ERRs at this moment is greater than the value of delay, the selector 40 instructs to pass the previous frame (that is, frame 7) to the decoder 2 again. Just after the frame 10 is received correctly, the quality determining device 6 will propose a signal INTERPOLATE # with a value of 2. The selector 36 thereby instructs to replace the output of the delay element 32 with the output of the delay element 34 to pass to the first input of the interpolator 38. At this time, the interpolator 38 calculates the Lpc parameter of the missing frame according to the following formula:

C: \ ProgramFUes \ Patent \ 55037.ptd Page 12 V. Description of the invention (9) Once the interpolated frames 8, and 9 'are decided, they will be passed to the decoder 20, as shown in Figure 50. Since the value of INTERPOLATE # is 2, the value delay is also set to 2, which instructs the selector 40 to pass the output signal of the delay element 32 to the decoder 20. After the interpolated frame is passed to the decoder 20, a frame will appear on the output of the 'delay element 32', so the frame 10 will be passed directly to the decoder 20 after the frame 9 '. It is shown in the figure 52 that the frame 13 is also missing. Since the number of errors indicated by the signal ERR is less than the delay value, the selector 40 will keep passing the output signal of the delay element 32 to the decoder 20. Only if the interpolation frame (ie, frame U) is calculated after receiving the INTERPOLATE # value from the quality determination device, the selector 40 will pass the interpolation frame used to replace the output signal of the delay element M to the decoder 2 〇. This is because the number of errors (ERR) does not exceed the value of DELAY, so no interruption occurs. If the period during which the shortage source signal is detected is prolonged, in order to make the delay not greater than necessary, the delay will be delayed. # Μhelmη 迸 The sigh value will be 0 again. The frame is not connected to the source signal. In the quality determining device 16 according to FIG. 5, the channel decoder number will reach the error detector 66 and the mute detection, including the frequency error detection including the presence of the output, indicating that there cannot be a short positive error. The error signal is not until the next signal == otherwise the error detector 60 will determine whether the received frame contains an uncorrectable error. Destroyer 97 In order to increase the count value, the error debt detector 66 will

C: \ Prograin Files \ Patent \ 55〇37. Ptd Page 13 4243 65 V. Description of the invention (ίο) By mistake, the technical signal is sent to the error counter 64, and the count value is passed to the maximum value determiner 62 and the signal representing the signal ERR. Output terminal. Only if this maximum value determinator 62 is greater than the output value it represents will replace the count value. The output signal of the maximum value determiner 62 represents the delay value in question, please refer to FIG. 3. The error detector 66 presents the signal of the first positive selection frame after one or more uncorrectable frames. This signal is used to reset the error counter. In order to activate the interpolation method to complete the uncorrectable frames, use This causes the buffer 16 to render its content as the output signal "^^ 奸 儿 六 丁 以. The mute detector decides the presentation of a predetermined number of frames carrying a very small or zero signal." If this number is reached, in order to interpolate The delay value in the device 14 (or the configuration device 14 + 18) is set to zero, and the mute detector resets the DELAY value on the output of the maximum value determiner 62 to 0. In the specific embodiment of the present invention according to FIG. The source signal to be transmitted will be sent to the encoder 8 to obtain the encoded signal. The output of the encoder 8 is connected to the input of the buffer 72, and the output signal (frame) of the buffer 72 is provided to the transmitter 10 for transmission. Go to the second node 4. The buffer 72 is used to temporarily store the frame provided to the transmitter 10 so that it can be obtained until the second node 4 requests retransmission. In the second node 4, the receiver 12 can be used From transmission The body obtains the signal from the first node 2. The output of the receiver 12 is connected to the first input of the selector? 4, the input of the buffer memory 7 and the turn of the error detector 76. The error detector 76 decides the second Whether node 4 correctly receives the frame transmitted by the first node 2. If the frame is received correctly, the error ㈣_ indicates

C: \ PrograraFiles \ Patent \ 55037.ptd page 14

Db. Description of the invention (ϊϊΤ ----— > = The selector 74 passes the output signal of the receiver 12 directly to the decoder 20, which is also shown in FIG. 7. The graph 7 9 shows that the encoder 8 generates the Figure 8 shows the sequence of the frames on the output of the receiver 12, and Figure η shows the sequence of the frames passed to the decoder. From Figure 7, it is clear that the receiver 12 is receiving the message Boxes 1, 2, and 3 are passed directly to the decoder 20. In the event that a transmission error is detected by the error detector 76, the selector 74 will instruct the previous box to be passed to the decoder 20. Error The detector 76 transmits a request for retransmission of the second incorrectly received frame through the transmitter 78. The buffer 7 is used to store the frame received before the incorrectly received frame before receiving the 3 retransmission frame. To be able to pass the frames to the decoder 2 in the correct order. Frame 4 must receive an error in frame 80. Error detector 76 will request retransmission of frame 4 and the transmitter will get frame 4 from buffer 72. And retransmitted to node 2. Regarding Figure 7, suppose the first node Retransmit polling frame 4 before transmitting frame 5, which can be achieved using the positive acknowledgement procedure, where the second μ point will confirm the reception of each frame. The reception of frames 8, 9 1 2 will be handled in the same way. 8 shows that if the negative acknowledgement is used, only the reception of the wrong receiving frame will be notified to the first node. From the figure 86, it can be seen that frame 5 has been received before retransmitting frame 4. In order to maintain the correct Frame order, frame 5 is temporarily stored in buffer 7 until the retransmitted frame 4 is received ° After the retransmitted frame 4 is passed to the decoder 20, the selector will delay the frame 5 Pass to decoder 20. To avoid until the next error

C: \ ProgramFiles \ Patent \ 55037.ptd Page 15 4243 6 5 5. Description of the invention (12) Interrupt before the error occurs. The selector 74 will keep the delayed frame to the decoder 2 0. If the two frames are lost, such as frames 7 and 8 in the relevant figure 86, then retransmission has occurred before any subsequent frames are transmitted to the second node 4. Therefore, no buffer is needed in this second node, and the received frame is directly passed to the decoder 50. When an error occurs, the same frame 7 is repeatedly passed to the decoder 20. However, a delay will be introduced in the first node at this time, which can be seen from the graphs 85 and 86. After the silence period occurs, the delay values in both the first and second nodes are reset to 0, as seen in graphs 85, 86, and 87. In the second node according to Fig. 9, an audio transmission according to the invention is shown. The receiver 90 receives the signal from the first node and passes it to the control device 92, which performs the function of the error detector and interpolator as explained with reference to the previous figure. The first output of the control device is carried to the decoder 9 4 with the received frame. The output signal of the decoder 9 4 is connected to the first input of the totalizer 9 7, and the output of the totalizer 9 7 is connected through the amplifier 9 8. To the horn 1 0 2. The second node further includes a microphone 104 connected to the encoder 110 through the amplifier 106, and the output of the encoder 110 is connected to the input of the transmitter 112 for transmitting the encoded signal to the first node. According to one area of the invention, the degree of comfort noise is introduced in accordance with the amount of delay. In addition, the control device 92 transmits the delay value DELAY to the comfort noise generator 96. The comfort noise generator 96 uses a noise signal that can increase the delay value to the level of the totalizer 97 to introduce the comfort noise signal to the speaker 102. °

L: \ EXT \ 55 \ 55037. PTD P.16

Case No. 87115650 V. Description of the invention (13) The delay value tone added according to the present invention indicates the degree of systemic transmission delay, which is the tone. From the control of the variable degree side Component symbol description 2 '6 4 8 10 13 14 16 18 20 22 24 26 28 30, 32, 34 36 38 40 Further areas of correction, the introduction of some sidetones can be gradually reduced. In order to allow the user to hear his own sound from the speaker, the side tone is introduced, but the side tone will become annoying echo in large cases. By increasing the delay and decreasing, it is possible to avoid the introduction of the amplifier 100 controlled by the delay value of the playback device 92 which is annoying due to the increase of the decoding delay. Node Transmission Media Source Encoder Transmitter Configuration Device Interpolator Quality Decision Device Selector Decoder Delay Element Output Input Selector Delay Element Selector Interpolator Selector

O: \ 55 \ 55037.ptc Page 17 2000.11.23.017

4-2 ^ 3 ti j ~~ ^ -.-'— I _ Case No. 87115650 1 / Ι ,: ψ ^: ΐ Amendment V. Description of the invention (14) L, _.. 42 Logic circuit 50 '52 Figure 60 Mute detector 62 Maximum value determiner 64 Error counter 66 Error detector 68 > 72 Buffer 1¾ 74 Selector 76 Error detector 78 Transmitter 79 '80, 81 graphics 85, 86 '87 graphics 90 receiver 92 Control device 94 Decoder 96 Comfort noise generator 97 Totalizer 98 Older device 100 Amplifier 1 02 Wei J 〇 104 104 Microphone 106 Amplifier 110 Stone horse maker 112 Transmitter

O: \ 55 \ 55037.ptc Page 17a 2000.11.23.018

Claims (1)

W43.S5 Amendment No. 87115 Lang n ', the patent application scope of its transmission system' includes-the first node of the encoder, the second, h input the flood number to take the 仵-encoding signal, the first node further contains the Body: The coded signal is transmitted to the transmitter of the second node, f ° 5 The coded signal obtains a reconstructed signal. The sign is that if the quality of the received coded signal is high, the reconstruction device is arranged to provide reconstruction immediately. The bat size 4 σσ Zhetu Γ, which is privately accepted for riding on 20 mouth shells, is only available for reconstruction, and if the 1Λ-quality is not met, the reconstruction-rank is provided after a reconstruction delay. Rebuild the signal.胄 The device is a transmission system that Maru declared the item 丨 of the patent scope, and is used to complete the reconstruction signal when the flood number is incomplete. The Administration wants to apply for the transmission system of item 1 of the patent scope, which is characterized by reconstructing the quality of the received encoded signal to reduce the reconstruction delay. For example, the transmission system of item i, 2 or 3 of the patent scope is characterized in that the reconstruction device is used to reduce the reconstruction delay after detecting the lack of a reconstruction signal. Ice 5 as. The transmission system of claim 1, 2, or 3 is characterized in that the source Λ number contains a voice signal, and the second node contains a comfort noise to introduce comfort noise to a degree that will gradually reduce the quality of the received coded signal. Import the device. 6. The transmission system according to the scope of patent application No. 丨, 2 or 3, characterized in that the transmission system includes a full-duplex voice transmission system, and the second node package is used to introduce the side tone side to the extent that the reconstruction delay is reduced Sound import device. For example, if the transfer system of the scope of the patent application item 2 is characterized by the completion of the missing part of the signal encoded by the point of the section-', the transfer system of the scope of the patent application item 2. , Characterized by the completion of Xiang O: \ 55 \ 55fB7.ptc _____ Case No. 87115650 Car? Month / Year Amendment_ 6. The scope of the patent application is to use the interpolation method of the surrounding part of the encoding or reconstruction signal to obtain the missing part of the encoding or reconstruction signal. 9. Types of nodes used in a transmission system include A reconstruction device that obtains a reconstructed sfL signal from an encoded signal is characterized in that if the quality of the received encoded signal meets certain quality standards, the reconstruction device is arranged to provide the reconstructed sfl signal immediately, and if the quality of the received encoded signal does not meet the quality The quality standard is that the reconstruction device is arranged to provide a reconstruction signal after a reconstruction delay. 10. A reconstruction device comprising a decoder for obtaining a reconstruction signal from an encoded signal, characterized in that if the quality of the received encoded signal meets certain quality standards, the reconstruction device is arranged to provide the reconstructed signal immediately, and if received If the quality of the encoded signal does not meet the quality standard, the reconstruction device is arranged to provide a reconstruction signal after a reconstruction delay. 11. A method for decoding an encoded signal, comprising obtaining a reconstructed signal from an encoded signal, characterized in that the method includes that if the quality of the received encoded signal meets certain quality standards, the encoded signal will be decoded immediately after receiving, And this method includes providing the reconstructed signal immediately if the quality of the received encoded signal meets certain quality standards, and providing the reconstructed signal after the reconstruction delay if the quality of the received encoded signal does not meet the quality standard. 2000. 08.31.019