Method and apparatus for transmitting and receiving signal in remote active noise control system

Abstract

The invention relates to a method and an apparatus for transmitting and receiving signals in a remote active noise control system. A method for transmitting and receiving a multi-channel signal between a vehicle and a server in a remote active noise control (ANC) system includes compressing, by the vehicle, the multi-channel signal for each channel using adaptive differential pulse code modulation (ADPCM), the multi-channel signal comprises at least one reference signal, at least one noise control signal and at least one error signal; constructing, by the vehicle, a packet for each predetermined transmission unit, the packet including the signal compressed for each channel, the corresponding channel information, and the corresponding ADPCM state information; transmitting, by the vehicle, the constructed packet to a server; the compressed signal for each channel is recovered by the server based on the received packets.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10 - 2023 - 0196358, filed on December 29, 2023, the entire content of which is incorporated herein for all purposes by this reference. Technical field

[0003] The present invention relates to a method and apparatus for transmitting and receiving signals in a remote ANC system. In a remote ANC system, there is a technology in which a vehicle compresses and transmits signals for each channel, and a server restores the received signals for each channel. Background art

[0004] The statements herein merely provide background information related to the present invention and do not necessarily constitute related art.

[0005] When a vehicle is in motion, air - induced noise and structure - borne noise are generated in the vehicle. For example, there is noise generated by the vehicle's engine, noise generated by the friction between the vehicle and the road surface, vibrations transmitted through the suspension, wind noise generated by the wind, etc.

[0006] Methods for reducing such noise include a passive noise control method and an active noise control (ANC) method. In the passive noise control method, sound - absorbing materials for absorbing noise are provided inside the vehicle, and the active noise control method uses a noise control signal having a phase opposite to that of the noise.

[0007] Since the passive noise control method has limitations in adaptively removing various noises, research on the active noise control method is being actively conducted. The road - noise active noise control (RANC) method for removing road noise in a vehicle has received much attention.

[0008] To perform active noise control, a noise control system of a vehicle generates a noise control signal having the same amplitude as the internal noise of the vehicle but having a phase opposite to that of the internal noise, and outputs the noise control signal to the interior of the vehicle to cancel the internal noise.

[0009] However, due to the low performance of the controller included in the vehicle, the controller has limitations in performing all active noise controls.

[0010] The information included in this background - art section of the present invention is only for deepening the understanding of the general background art of the present invention and should not be regarded as an admission or an implication in any form that this information constitutes the prior art known to those skilled in the art. SUMMARY OF THE INVENTION

[0011] Aspects of the present invention are directed to providing a remote ANC system and an operating method thereof. The remote ANC system includes a remote server and a vehicle. The remote server is configured to perform an update of an adaptive filter, and the vehicle uses the updated adaptive filter to generate a noise control signal.

[0012] Exemplary embodiments of the present invention provide a method and an apparatus for compressing signals for each channel using ADPCM in a remote ANC system and transmitting corresponding channel information, ADPCM state information, and the compressed signals together.

[0013] The problems to be solved by the present invention are not limited to the above problems, and those skilled in the art will clearly understand other problems not mentioned from the following description.

[0014] According to at least one exemplary embodiment of the present invention, there is provided a method for transmitting and receiving multi-channel signals between a vehicle and a server in a remote active noise control (ANC) system. The method includes: using, by the vehicle, adaptive differential pulse code modulation (ADPCM) to compress a multi-channel signal for each channel, the multi-channel signal including at least one reference signal, at least one noise control signal, and at least one error signal; constructing, by the vehicle, a packet for each predetermined transmission unit, the packet including the signal compressed for each channel, corresponding channel information, and corresponding ADPCM state information; transmitting, by the vehicle, the constructed packet to the server; and restoring, by the server, the signal compressed for each channel based on the received packet.

[0015] According to another exemplary embodiment of the present invention, there is provided an apparatus for transmitting multi-channel signals included in a vehicle in a remote active noise control (ANC) system. The apparatus includes: a memory and at least one processor. The memory is configured to store instructions. The at least one processor executes the instructions to compress a multi-channel signal for each channel using adaptive differential pulse code modulation (ADPCM), the multi-channel signal including at least one reference signal, at least one noise control signal, and at least one error signal; construct a packet for each predetermined transmission unit, the packet including the signal compressed for each channel, corresponding channel information, and corresponding ADPCM state information; and transmit the constructed packet to the server.

[0016] According to another exemplary embodiment of the present invention, the present invention provides a device for receiving a multi-channel signal included in a server in a remote active noise control (ANC) system. The device includes: a memory and at least one processor, the memory being configured to store instructions; wherein, the at least one processor executes the instructions to receive packets from at least one vehicle; and recover the signals compressed for each channel based on the received packets.

[0017] As described above, according to the exemplary embodiment of the present invention, by distributing the noise control algorithm to the vehicle and the server, the update delay of the adaptive filter can be prevented and the noise control performance can be improved.

[0018] According to another exemplary embodiment of the present invention, by compressing and transmitting signals between the vehicle and the server in a remote ANC system, the amount of data transmission can be reduced.

[0019] According to another exemplary embodiment of the present invention, by sharing the ADPCM state information related to signal compression in a remote ANC system between the vehicle and the server, the accuracy of the update of the adaptive filter can be improved.

[0020] The effects of the present invention are not limited to the above effects, and those skilled in the art can clearly understand other effects not mentioned from the following description.

[0021] The method and device of the present invention have other features and advantages, which will be apparent from the accompanying drawings incorporated herein and the subsequent detailed description, or will be described in detail in the accompanying drawings incorporated herein and the subsequent detailed description. These accompanying drawings and detailed description are used together to explain the specific principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic diagram showing components of a vehicle according to an exemplary embodiment of the present invention.

[0023] Figure 2 is a schematic diagram showing a noise control method according to an exemplary embodiment of the present invention.

[0024] Figure 3 is a schematic diagram of a noise control algorithm according to an exemplary embodiment of the present invention.

[0025] Figure 4 is a schematic diagram showing a remote ANC system according to an exemplary embodiment of the present invention.

[0026] Figure 5 is a schematic diagram of a remote ANC system according to an exemplary embodiment of the present invention.

[0027] Figure 6Aand Figure 6B are respectively simplified block diagrams of an ADPCM encoder and an ADPCM decoder.

[0028] Figure 7 is a flowchart of a method for transmitting and receiving signals between a vehicle and a server in a remote ANC system according to an exemplary embodiment of the present invention.

[0029] It can be understood that the accompanying drawings are not necessarily drawn to scale, presenting a suitably simplified representation of various features illustrating the basic principles of the present invention. Specific design features of the present invention as included herein (including, for example, specific dimensions, orientations, positions, and shapes) will be determined in part by the specific environment in which it is to be applied and used.

[0030] In the drawings, throughout the several views of the drawings, the same reference numerals refer to the same or equivalent parts of the present invention. Detailed Description of the Invention

[0031] Reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. Although the present invention will be described in conjunction with the exemplary embodiments of the present invention, it should be understood that this description is not intended to limit the present invention to those exemplary embodiments. On the other hand, the present invention is intended to cover not only the exemplary embodiments of the present invention, but also various alternative embodiments, modified embodiments, equivalent embodiments, and other embodiments that may be included within the spirit and scope of the present invention as defined by the appended claims.

[0032] Hereinafter, various exemplary embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same reference numerals denote the same elements, although they are shown in different drawings. In addition, for the sake of clarity and brevity, when a detailed description of related known components and functions is considered to obscure the subject matter of the present invention, the following description of various exemplary embodiments will omit the detailed description of related known components and functions.

[0033] Various ordinal numbers or alphabetic codes such as first, second, i), ii), a), b), etc. are only used as prefixes to distinguish one component from another, rather than teaching or implying the substance, order, or sequence of the components. Throughout the specification, when a component "includes" or "comprises" a component, the component is intended to further include other components, rather than excluding other components, unless specifically stated to the contrary. Terms such as "unit", "module", etc. refer to a unit that processes at least one function or operation, and they can be implemented by hardware, software, or a combination thereof.

[0034] The description of the present invention presented below in conjunction with the accompanying drawings is intended to describe exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the technical idea of the present invention can be practiced.

[0035] Figure 1 is a schematic diagram showing components of a vehicle according to an exemplary embodiment of the present invention.

[0036] Reference Figure 1 , a vehicle 10 is shown. The vehicle 10 includes: wheels 100, a suspension device 110, a reference sensor 120, a microphone 130, a controller 140, a speaker 150, and an axle 160. In Figure 1 , the number and arrangement positions of the plurality of components correspond to an exemplary embodiment of the present invention. In other exemplary embodiments of the present invention, the number and positions of the components may be changed.

[0037] The vehicle 10 includes a chassis and a noise control system. Accessories required for driving are mounted on the chassis, and the noise control system is configured to perform active noise control. The vehicle 10 may further include at least one of a driving device, a steering device, and a braking device.

[0038] The chassis of the vehicle 10 includes the wheels 100 of the vehicle 10. The wheels 100 include front wheels and rear wheels. The front wheels are arranged on the left and right sides of the front part of the vehicle 10, and the rear wheels are arranged on the left and right sides of the rear part of the vehicle 10. The chassis of the vehicle 10 may further include an axle 160 (which serves as a power transmission device), a suspension device 110 (which serves as a shock-absorbing device), and a body. Here, the suspension device 110 is a device that reduces the vibration or impact of the vehicle 10. When the vehicle 10 is running, vibrations caused by the road surface are applied to the vehicle 10. The suspension device 110 uses springs, air suspensions, etc. to reduce the vibrations applied to the vehicle 10. The suspension device 110 can improve the riding comfort of the occupants sitting in the vehicle 10 by reducing the impact.

[0039] However, noise may be generated inside the vehicle 10 through the suspension device 110. The suspension device 110 is capable of reducing the large vibrations applied to the vehicle 10, but it is difficult to eliminate the minute vibrations caused by the friction between the wheels 100 and the road surface. These minute vibrations generate noise inside the vehicle 10 through the suspension device 110. In addition, noise generated by the friction between the wheels 100 and the road surface, noise generated by an engine as a power device, or wind noise generated by the wind may flow into the interior of the vehicle 10.

[0040] To eliminate the noise inside the vehicle 10, the vehicle 10 may include a noise control system. The noise control system of the vehicle 10 may utilize a noise control signal for the noise inside the vehicle 10 to attenuate the noise inside the vehicle 10, and the noise control signal has the same amplitude as the noise signal and has a phase opposite to that of the noise signal.

[0041] For this purpose, the noise control system includes: a reference sensor 120, a microphone 130, a controller 140, and a speaker 150. The noise control system may further include an amplifier (AMP) for audio playback.

[0042] The reference sensor 120 generates a reference signal and sends the reference signal to the controller 140, and the reference signal represents the vibration caused by the friction between the wheel 100 and the road surface. In this case, the reference sensor 120 sends the reference signal to the controller 140 in the form of an analog signal. As an alternative, the reference sensor 120 may convert the reference signal into a digital signal and send the converted digital signal to the controller 140.

[0043] Here, the reference sensor 120 may be an accelerometer. An accelerometer is a device that generates an acceleration signal representing the acceleration of the vehicle 10. The accelerometer is used to measure the vibration of the vehicle 10. In other words, the reference sensor 120 may be configured to generate a reference signal according to the vibration of the vehicle 10, and the reference signal represents the acceleration signal. The reference sensor 120 is a triaxial accelerometer and can measure the vibration along three perpendicular axes.

[0044] The reference sensor 120 may be arranged on the suspension device 110, on the connecting mechanism connecting the wheel 100 and the axle 160, or on the vehicle body.

[0045] The noise control system may use at least one of a gyro sensor, a motion sensor, a displacement sensor, a torque sensor, and a microphone as the reference sensor to measure the vibration of the vehicle 10.

[0046] The microphone 130 detects the sound inside the vehicle 10. The microphone 130 may detect the noise inside the vehicle 10. For example, the microphone 130 may measure the sound pressure of about 20 Hz to 20 kHz (which is the audible frequency band of humans). The listening frequency range of the microphone 130 may be narrower or wider. In an exemplary embodiment of the present invention, the microphone 130 may measure the noise flowing into the vehicle 10 due to the friction between the wheel 100 and the road surface.

[0047] When a noise control signal is output to the interior of the vehicle 10 for noise control, the microphone 130 can measure the noise signal remaining in the interior of the vehicle 10 in an environment where the noise in the interior of the vehicle 10 is removed by the noise control signal. The residual noise is measured by the microphone 130 as an error signal or a residual signal. The error signal can be used as information for determining whether the noise in the interior of the vehicle 10 has been normally reduced or eliminated.

[0048] When an audio signal is further output to the interior of the vehicle 10, the acoustic signal from the microphone 130 can include an error signal and an audio signal.

[0049] The controller 140 generates a noise control signal for removing the noise inside the vehicle based on the reference signal of the reference sensor 120 and the error signal. The controller 140 can be configured to generate a noise control signal that has the same amplitude as the noise signal but has a phase opposite to that of the noise signal. The controller 140 can convert the reference signal and the error signal, which are analog signals, into digital signals and generate a noise control signal based on the converted digital signals.

[0050] When the noise control system includes an amplifier, the amplifier receives the noise control signal from the controller 140, receives the audio signal from an audio, video, navigation (AVN) device, mixes the noise control signal with the audio signal, and outputs the mixed signal through the speaker.

[0051] The amplifier can use an amplification circuit to adjust the amplitude of the mixed signal. The amplification circuit can include a vacuum tube or a transistor for amplifying the power of the mixed signal.

[0052] The speaker 150 receives the mixed signal (which is an electrical signal) from the amplifier or receives the noise control signal from the controller 140 and outputs the mixed signal or the noise control signal in the form of sound waves inside the vehicle 10. The noise inside the vehicle 10 can be reduced or eliminated through the mixed output of the speaker 150, and the noise at the position of the microphone 130 or the occupant's ear can be minimized as much as possible.

[0053] The speaker 150 can output the noise control signal only to a specific occupant. The speaker 150 outputs noise control signals with different phases at multiple positions inside the vehicle 10, thereby causing constructive interference or destructive interference at the position of the specific occupant's ear.

[0054] Figure 2 It is a schematic diagram showing a noise control method according to an exemplary embodiment of the present invention.

[0055] Reference Figure 2, the noise control system of the vehicle includes: a sensor 210, a controller 220, a speaker 230, and a microphone 240.

[0056] The noise control system of the vehicle eliminates noise in the vehicle by outputting a noise control signal generated based on a reference signal from the sensor 210. Here, the noise control signal is a signal having the same amplitude as the noise signal but having a phase opposite to that of the noise signal. In addition, the noise control system can also remove residual noise inside the vehicle by using the residual noise remaining after noise removal as feedback.

[0057] When the vehicle is running, vibrations are generated due to the friction between the vehicle and the road surface, and the generated vibrations cause noise inside the vehicle. The vibrations are measured by the sensor 210 as an electrical signal.

[0058] The controller 220 receives the reference signal measured by the sensor 210.

[0059] The controller 220 generates a noise control signal for attenuating the noise inside the vehicle by applying an adaptive filter to the reference signal. The controller 220 is configured to determine the filter coefficients of an adaptive filter (commonly referred to as the W filter) based on an error signal and a reference signal according to an algorithm such as the least mean square (LMS) or filtered-x least mean square (FxLMS) well known in the art. After that, the controller 220 generates a noise control signal by applying the filter coefficients to the obtained reference signal. The reference signal becomes the noise control signal through convolution calculation with the filter coefficients.

[0060] The controller 220 outputs the noise control signal through the speaker 230. When the noise control signal is played through the speaker 230, the sound pressure level of the road noise at the position of the speaker 230 is reduced.

[0061] On the other hand, the path between the sensor 210 and the speaker 230 is called the primary path or the main sound path. The primary path is a model representing the acoustic transfer characteristics from the sensor 210 to the speaker 230.

[0062] In this case, due to the distance difference between the position of the speaker 230 that outputs the noise control signal and the position of the occupant's ear, residual noise may occur at the occupant's listening position. For example, since the noise control signal output from the speaker 230 changes when it propagates to the occupant's listening position, the noise may not be completely removed from the position of the occupant's ear. In addition, since the noise control signal generated by the controller 220 changes when it passes through the amplifier or the speaker 230, this may be different from the noise at the occupant's listening position. This residual noise can be represented as an error signal, which represents the difference between the noise signal and the changed noise control signal at the occupant's listening position.

[0063] To remove residual noise, a noise control system may include a microphone 240 located near the position of the occupant's ear, and the signal measured by the microphone 240 may be estimated as residual noise. Herein, the path between the speaker 230 and the microphone 240 is referred to as the secondary path. The noise control system may pre-store the transfer function for the secondary path between the speaker 230 and the microphone 240.

[0064] The controller 220 receives the error signal fed back from the microphone 240, and uses the acoustic transfer characteristics of the secondary path, the reference signal, and the error signal to update the filter coefficients of the adaptive filter. The controller 220 generates a noise control signal by applying the updated coefficients of the adaptive filter to the reference signal. The noise control signal has an ideal waveform such that when the noise control signal is played through the speaker 250 via an amplifier, a cancellation sound is generated at a position near the microphone 240, and the cancellation sound has a phase substantially opposite to and the same magnitude as the road noise heard by the occupant in the vehicle cabin. The cancellation sound from the speaker 230 encounters the road noise near the microphone 240 in the vehicle cabin, so that the sound pressure level caused by the road noise at the current position can be reduced. That is, the noise control signal based on the secondary path can reduce the noise and residual noise at the position of the microphone 240. When the microphone 240 is closer to the listening position of the occupant, the microphone 240 can measure the residual noise closer to the listening position of the occupant. When the microphone 240 is arranged at a position near the occupant's ear, it is beneficial to remove the residual noise.

[0065] On the other hand, the noise control system of the vehicle can use a virtual microphone to more accurately model the secondary path. The controller 220 can generate a virtual microphone at the position of the occupant's ear, and obtain accurate information on the acoustic transfer characteristics between the speaker 230 and the listening position of the occupant based on the signal measured by the virtual microphone. The secondary path may include the path between the speaker 230 and the microphone 240 and the path between the microphone 240 and the virtual microphone.

[0066] Through the above process, the noise control system of the vehicle can further weaken the residual noise at the position of the occupant's ear and can improve the performance of active noise control.

[0067] Figure 3 is a schematic diagram of a noise control algorithm according to an exemplary embodiment of the present invention.

[0068] Reference Figure 3 , shows a primary path 310, a secondary path 320, a controller 330, an adaptive filter 332, a secondary path model 334, an adaptive filter controller 336, and a virtual error signal estimator 338. The controller 330 is a device included in the vehicle.

[0069] Figure 3 The noise control algorithm shown involves a single-channel feedforward FxLMS algorithm. In other exemplary embodiments of the present invention, a multi-channel structure with multiple additional channels, multiple additional microphones, and multiple additional speakers can also be employed, and an algorithm for the multi-channel structure can be used. For example, 12 acceleration sensors and 8 speakers can be used, and a total of 12×8 sets of filter coefficients can be used for the algorithm. Each set of filter coefficients includes at least one filter coefficient. Hereinafter, a noise control algorithm based on one sensor and one speaker will be described. In addition, n represents the sampling time, and z represents the frequency.

[0070] The reference signal x(n) is detected by a reference sensor of the vehicle. For example, the reference signal x(n) can be a measurement signal of an accelerometer or a vibration sensor. The reference signal x(n) becomes the noise signal d(n) through the primary path 310. The primary path 310 represents the reference sensor and the speaker path. The acoustic transfer characteristic P(z) of the primary path 310 refers to the relationship between the reference signal x(n) and the noise signal d(n). The noise signal d(n) is the noise at the position that the controller 330 wants to control. For example, the noise signal d(n) represents the noise at the position of the occupant's ear.

[0071] The controller 330 uses an adaptive control algorithm to generate a noise control signal y(n) for removing the noise signal d(n). The noise control signal y(n) is a signal for removing or weakening the noise signal d(n).

[0072] As the adaptive control algorithm, the controller 330 can use various algorithms such as Filtered-input Least Mean Square (FxLMS), Filtered-input Normalized Least Mean Square (FxNLMS), Filtered-input Recursive Least Square (FxRLS), and Filtered-input Normalized Recursive Least Square (FxNRLS).

[0073] Specifically, the controller 330 uses an adaptive filter 332, a secondary path model 334, and an adaptive filter controller 336 to generate a noise control signal y(n). First, the adaptive filter 332 receives a reference signal x(n) and generates a noise control signal y(n) for removing a noise signal d(n). The transfer function of the adaptive filter 332 can be expressed as W(z), and the transfer function W(z) of the adaptive filter 332 can represent at least one filter coefficient. The noise control signal y(n) can be derived by a convolution calculation between the reference signal x(n) and the transfer function W(z) of the adaptive filter 332.

[0074] The noise control signal y(n) is output through a speaker, and the noise control signal y(n) is transformed when passing through the secondary path 320. Here, when the position of the occupant's ear is regarded as the same as the position of the microphone, the secondary path 320 is the path between the speaker and the microphone. That is, the noise control signal y(n) becomes a transformed noise control signal y’(n) at the position of the physical microphone. The transformed noise control signal y’(n) and the noise signal d(n) cancel each other out at the position of the physical microphone. However, even when the noise control signal y(n) at the position of the speaker is generated to be the same as the noise signal d(n), the noise control signal y’(n) transformed through the secondary path 320 is different from d(n), resulting in residual noise at the position of the physical microphone.

[0075] The residual noise at the position of the physical microphone is measured by the physical microphone as an error signal e(n). Here, the error signal e(n) represents the residual noise remaining after the noise signal d(n) is canceled by the noise control signal y(n) at a noise control point such as the position of the physical microphone.

[0076] To remove the error signal e(n), the controller 330 can update the filter coefficients of the adaptive filter 332 based on the reference signal x(n) and the error signal e(n). In other words, the adaptive filter controller 336 implemented on the controller 330 updates the filter coefficients by considering that the noise control signal y(n) is transformed through the secondary path 320 after the noise control signal y(n) is output from the speaker.

[0077] However, the error signal e(n) represents the residual noise measured at the position of the physical microphone, so the error signal e(n) is different from the residual noise at the position of the occupant's ear. Even if the microphone configured to measure the error signal e(n) is arranged close to the position of the occupant's ear, due to the distance difference between the position of the microphone and the position of the occupant's ear, the residual noise at the position of the occupant's ear is a virtual error signal e’(n) rather than the error signal e(n).

[0078] Therefore, it is necessary to estimate the virtual error signal e’(n) at the position of the occupant's ear and remove the virtual error signal e’(n).

[0079] First, the transfer function S’(z) of the secondary path model 334 can be pre-estimated, which represents the acoustic transfer characteristics of the secondary path 320. For example, when there is no noise in the vehicle, the secondary path model 334 can be estimated based on the output of the speaker and the input of the microphone. In addition to the above modeling method, an appropriate method in the modeling methods can be used by an engineer in the field of noise control to model the secondary path 320 to best explain the physical phenomena of the actual audio system.

[0080] The controller 330 applies the secondary path model 334 to the reference signal x(n), so that the reference signal x(n) becomes the filtered reference signal x’(n). The filtered reference signal x’(n) is input to the adaptive filter controller 336.

[0081] The virtual error signal estimator 338 estimates the virtual error signal e’(n) at the position of the occupant's ear based on the noise control signal y(n) and the error signal e(n). The virtual error signal estimator 338 can be configured to generate a virtual microphone at the position of the occupant's ear based on the noise control signal y(n) and the error signal e(n). Different from the physical microphone, the virtual microphone has the concept of estimating the acoustic signal according to the position of the occupant's ear. The virtual error signal estimator 338 can use the virtual microphone to measure the virtual error signal e’(n) at the position of the occupant's ear.

[0082] The virtual error signal estimator 338 pre-stores a first acoustic transfer characteristic from the speaker to the physical microphone, a second acoustic transfer characteristic from the position of the physical microphone to the position of the expected occupant's ear, and a third acoustic transfer characteristic from the speaker to the position of the expected occupant's ear. Thereafter, the virtual error signal estimator 338 applies the first acoustic transfer characteristic to the noise control signal y(n) to estimate the transformed noise control signal y'(n) at the physical microphone position. The virtual error signal estimator 338 estimates the noise signal d(n) at the physical microphone position by subtracting the transformed noise control signal y'(n) from the error signal e(n). Thereafter, the virtual error signal estimator 338 estimates the virtual noise signal d'(n) at the position of the expected occupant's ear by applying the second acoustic transfer characteristic to the noise signal d(n). In addition, the virtual error signal estimator 338 estimates the virtual noise control signal y''(n) at the position of the expected occupant's ear by applying the third acoustic transfer characteristic to the noise control signal y(n). The virtual noise control signal y''(n) is estimated to be a signal having the same amplitude as the virtual noise signal d'(n) at the position of the expected occupant's ear and having a phase opposite to that of the noise signal. However, due to various factors, the virtual noise signal d'(n) may not be the same as the virtual noise control signal y''(n). Accordingly, the virtual error signal estimator 338 may add the virtual noise signal d'(n) to the virtual noise control signal y''(n) to obtain a virtual error signal e'(n), which represents the virtual residual noise remaining after removing the virtual noise signal d'(n) by the virtual noise control signal y''(n).

[0083] Therefore, the adaptive filter controller 336 applies the least mean square (LMS) algorithm to the filtered reference signal x'(n) and the virtual error signal e'(n) to update the filter coefficients of the adaptive filter 332. The filter coefficients are updated so that the virtual error signal e'(n) is 0. The filter coefficients W(z) can be updated by gradient descent.

[0084] The updated adaptive filter 332 generates a noise control signal y(n) based on the reference signal x(n). When the noise control signal y(n) is output from the speaker, the virtual error signal e'(n) measured at the virtual microphone position is minimized. That is, the noise according to the reference signal x(n) is removed as much as possible at the position of the expected occupant's ear.

[0085] Through the above process, the controller 330 can adaptively generate the noise control signal y(n).

[0086] On the other hand, in other exemplary embodiments of the present invention, the virtual error signal estimator 338 may be omitted. In this case, the adaptive filter controller 336 may update the filter coefficients of the adaptive filter 332 based on the filtered reference signal x'(n) and the error signal e(n) to make the error signal e(n) zero.

[0087] On the other hand, unless the controller 330 included in the vehicle is an expensive digital signal processor, due to performance limitations, it may be difficult for the controller 330 to perform all of the above signal processing. In the noise control algorithm, the update of the filter coefficients of the adaptive filter 332 requires the largest amount of computation. The convolution calculation between the adaptive filter 332 for generating the noise control signal y(n) and the reference signal x(n) and the virtual microphone processing calculation of the virtual error signal estimator 338 account for the second highest proportion. The update of the filter coefficients requires much more computation than other calculations. As an exemplary embodiment of the present invention, the filter coefficient update may account for 85% of the total computation of the noise control algorithm. It may be limited for the controller 330 to process all of these calculations.

[0088] Therefore, according to an exemplary embodiment of the present invention, the noise control algorithm may be processed distributively.

[0089] Figure 4 is a schematic diagram showing a remote ANC system according to an exemplary embodiment of the present invention.

[0090] Reference Figure 4 , the remote active noise control (ANC) system includes a vehicle 41 and a server 42. The remote ANC system is a system for executing the process of the noise control algorithm assigned to the vehicle 41 and the server 42.

[0091] Figure 4 The shown noise control algorithm is the same as or similar to Figure 3 The shown noise control algorithm. The adaptive filter controller 425 is configured to perform the operations of the adaptive filter controller 336, and the secondary path model 421 is the same as the secondary path model 334. The primary path 430 is the same as the primary path 310, and the secondary path 440 is the same as the secondary path 320. In addition, the virtual error signal estimator 427 is configured to perform the functions of the virtual error signal estimator 338. However, Figure 4 the noise control algorithm is partially executed not only in the vehicle 41 but also in the server 42.

[0092] Vehicle 41 may include a controller 410 with relatively limited performance, and the server 42 may include a computing device 420 with relatively higher performance. In addition, each of the vehicle 41 and the server 42 includes a communication device for wireless communication with each other. The communication device may perform various communications including multi-generation mobile communication technologies, local area network (LAN) communication, and vehicle-to-everything (V2X) communication. In addition, the server 42 may be a cloud computing device, and the server 42 may provide the filter coefficient update operation described below to multiple vehicles.

[0093] First, a reference signal x(n) is collected from the reference sensors of the vehicle 41. The controller 410 in the vehicle 41 generates a noise control signal y(n) by applying a local adaptive filter 411 to the reference signal x(n). At the same time, an error signal e(n) is measured at the microphone in the vehicle 41.

[0094] The vehicle 41 sends the reference signal x(n), the noise control signal y(n), and the error signal e(n) to the server 42.

[0095] The computing device 420 in the server 42 uses the reference signal x(n), the noise control signal y(n), and the error signal e(n) to update the filter coefficients of the remote adaptive filter 423. The computing device 420 can accelerate the processing of the noise control algorithm by performing the filter coefficient update, which occupies the largest amount of computation in the noise control algorithm. Here, since the update process of the remote adaptive filter 423 is the same as the filter coefficient update process of the adaptive filter 332 described in Figure 3 it will be omitted from its detailed description.

[0096] The computing device 420 obtains the updated filter coefficients W’(z) as a result of updating the remote adaptive filter 423, and sends the updated filter coefficients W’(z) to the controller 410 of the vehicle 41 through wireless communication.

[0097] The controller 410 receives the updated filter coefficients W’(z), and replaces the filter coefficients W(z) of the local adaptive filter 411 with the updated filter coefficients W’(z). After that, the reference signal x(n) becomes the noise control signal y(n) through the calculation with the updated filter coefficients W’(z).

[0098] By repeating the above process, the vehicle 41 and the server 42 in the remote ANC system can implement the noise control algorithm.

[0099] The low-performance controller 410 is configured to perform replacement and application of the local adaptive filter 411 that requires less computational load, and the high-performance computing device 420 is configured to perform the filter coefficient update operation of the adaptive filter controller 425 that requires greater computational load. Thus, since the noise control algorithm is processed distributively, the update of the filter coefficients of the local adaptive filter 411 can be performed quickly without delay.

[0100] In addition, the adaptive control algorithm of all vehicles connected to the server 42 can be changed by only changing the adaptive control algorithm of the adaptive filter controller 425 of the server 42 without changing the software of the controllers included in all vehicles.

[0101] In another exemplary embodiment of the present invention, the vehicle 41 may send the reference signal x(n) and the error signal e(n) to the server 42, and the server 42 may be configured to generate and return the noise control signal y(n). However, compared with the scheme in which the server 42 sends the updated filter coefficients W’(n), problems such as an increase in delay and low noise control performance due to the increase in delay may occur.

[0102] Figure 5 is a schematic diagram of a remote ANC system according to an exemplary embodiment of the present invention.

[0103] Reference Figure 5 , the remote ANC system includes a vehicle 510 and a server 520.

[0104] The vehicle 510 includes: a reference sensor 511, a speaker 513, a microphone 515, a controller 517, and a first communication module 519. Each reference sensor 511 may be an accelerometer and measures an acceleration signal as a reference signal when the vehicle 510 is traveling. Each speaker 513 outputs a noise control signal. Each microphone 515 receives an error signal. The controller 517 applies the updated filter coefficients received from the server 520 to the reference signal to generate a noise control signal. The first communication module 519 supports a connection for wireless communication with the server 520 and exchanges signals and filter coefficients with the second communication module 521 of the server 520. In addition, the first communication module 519 may include a signal buffer for synchronization.

[0105] The server 520 includes: a second communication module 521, a processor 523, and a memory 525. The second communication module 521 supports wireless communication with the first communication module 519. In addition, the second communication module 521 may include a signal buffer for synchronization. The processor 523 updates the remote adaptive filter by using the reference signal, the noise control signal, and the error signal received from the vehicle 510. That is, the processor 523 may perform the functions of the computing device 420. The memory 525 stores instructions for enabling the processor 523 to perform filter coefficient updates.

[0106] The server 520 may update the filter coefficients at regular time intervals and periodically. For example, the update period of the filter coefficients may be set to 64 ms. The server 520 may update the filter coefficients every 64 ms based on the signals received from the vehicle 510. When the update period of the filter coefficients in the server 520 is shorter, the noise control performance in the vehicle 510 can be further improved.

[0107] On the other hand, in order to distributively process the noise control algorithm in the remote ANC system, it is necessary to continuously exchange various signals and updated filter coefficients between the vehicle 510 and the server 520. The amount of data of the reference signal x(n), the noise control signal y(n), and / or the error signal e(n) transmitted from the vehicle 510 to the server 520 is very large. When a large amount of data is transmitted as it is, the overall performance of the remote ANC system may deteriorate due to transmission delay or error. Therefore, it is necessary to reduce the amount of data transmission.

[0108] To this end, in the remote ANC system according to an exemplary embodiment of the present invention, the vehicle 510 compresses multi-signals including at least one of the reference signal x(n), the noise control signal y(n), and the error signal e(n), and transmits the compressed signals to the server 520. Here, the reference signal includes as many channels as the number (e.g., R) of reference sensors 511 arranged in the vehicle 510. Here, the noise control signal includes as many channels as the number (e.g., K) of speakers 513 arranged in the vehicle 510. Here, the error signal includes as many channels as the number (e.g., M) of microphones 515 arranged in the vehicle 510. That is, the multi-signals may include at least one of R reference channel signals, K noise control channel signals, and M error channel signals.

[0109] In a remote ANC system, the reference signal, the noise control signal, and the error signal are compressed and restored for each channel. This is because the correlation between the reference channel signal, the noise control channel signal, and the error channel signal is relatively low. That is, the reference signal, the noise control signal, and the error signal are compressed for each channel in the vehicle 510, and the reference signal, the noise control signal, and the error signal are restored for each channel in the server 520.

[0110] The remote ANC system can use the adaptive differential pulse code modulation (ADPCM) algorithm to encode or decode multiple signals. ADPCM is a technique that uses adaptive quantization and differential predictive coding to effectively compress pulse code modulation (PCM) signals. First, the ADPCM encoder and decoder will be briefly described.

[0111] Figure 6A is a simplified block diagram of a conventional ADPCM encoder. Refer to Figure 6A , by utilizing the characteristics of the sound signal that has a high correlation with the values of adjacent samples to obtain the difference signal between the input signal and the signal estimation and quantize the difference signal, thereby encoding the sound signal. That is, by quantizing the difference signal of the 64 kbps (8 kHz × 8) PCM input signal into 4 bits, the sound signal can be encoded at a bit rate of 32 kbps (8 kbps × 4).

[0112] The ADPCM encoder converts the 64 kbps PCM of μ-law or A-law as the input signal into a uniform PCM signal, and obtains the difference signal by subtracting the predicted signal from the current signal. A 15-level adaptive quantizer is used for the quantization of the difference signal, and a 4-bit code is assigned to each quantization level. The output signal of the adaptive quantizer becomes the output signal of the ADPCM encoder.

[0113] Figure 6B is a simplified block diagram of a conventional ADPCM decoder. Refer to Figure 6B , in the ADPCM decoder, the 4-bit ADPCM encoded signal as the input signal is converted into a difference signal quantized by a 15-level inverse adaptive quantizer. In the adaptive predictor, the quantized difference signal and the decoded signal of the previous sample can be used to obtain the predicted signal. By adding the predicted signal, which is the output of the adaptive predictor, to the difference signal, the decoded signal of the input signal can be obtained. The signal path used to determine the predicted signal in the adaptive predictor is the same as the circuit in the ADPCM encoder.

[0114] As described above, ADPCM is a method of compressing the difference between the current sample and the previous sample by using the size of the quantization step adaptively found according to the magnitude of the change. The encoder and decoder internally manage the value of the previous sample, etc.

[0115] On the other hand, a remote ANC system needs to perform compression and restoration for each channel of a multi-signal. Incidentally, since ADPCM generally compresses and restores a continuous PCM signal of a single channel, when the channel of the multi-signal changes, compression may be performed based on new data, which results in a discontinuity point during compression and restoration in ADPCM, thereby reducing the accuracy of restoration. This is because the adaptive predictor of the ADPCM decoder continuously updates the information about the magnitude of the difference of the existing data, and the initial PCM output of the decoder becomes different from the actual value due to the change in the channel of the multi-signal.

[0116] To solve this problem, the internal information of the adaptive predictor of the encoder is shared with the decoder.

[0117] In a remote ANC system, the corresponding channel information and ADPCM state information are exchanged in a predetermined transmission unit together with the signals compressed for each channel. That is, the vehicle 510 transmits together the compressed signals of each channel, the corresponding channel information, and the corresponding ADPCM state information for each predetermined transmission unit, and the server 520 restores the corresponding compressed signals of each channel based on the received corresponding channel information and corresponding ADPCM state information. Here, the transmission unit refers to the number N of ADPCM output samples of each channel (for example, 256 for each channel) or the transmission period, and can be preset or changed. Here, the channel information refers to the channel identifier information assigned to distinguish the reference channel signal, the noise control channel signal, and the error channel signal. Here, the ADPCM state information is the information managed within the ADPCM encoder, refers to the internal information of the adaptive predictor of the ADPCM encoder, and includes the value of the previous input sample of the ADPCM encoder for each transmission unit and the index of the table of the quantization step size used when compressing the previous input sample. The value of the previous sample may represent the value of the first sample in the transmission unit.

[0118] The remote ANC system can use the user datagram protocol (UDP) to send and receive the compressed multi-signal. This is because the remote ANC system requires a high transmission speed for large data rather than transmission reliability.

[0119] In a remote ANC system, vehicle 510 constructs UDP packets for each predetermined transmission unit, the UDP packets including channel information, ADPCM status information, and signals compressed for each channel, and transmits the constructed UDP packets to server 520. An example of the data included in the payload of the UDP packets transmitted from the vehicle to the server is shown in Table 1.

[0120] (Table 1)

[0121]

[0122] In a remote ANC system, server 520 analyzes the received UDP packets, extracts the channel information, ADPCM status information, and ADPCM output samples for each channel, and restores the compressed signals of the channels based on the channel information and ADPCM status information of each channel. Server 520 can use the restored signals to update the filter coefficients of remote adaptive filter 423. Server 520 transmits the updated filter coefficients to vehicle 510. Server 520 can compress the updated filter coefficients and transmit the updated filter coefficients to vehicle 510.

[0123] Figure 7 is a flowchart of a method for transmitting and receiving signals between a vehicle and a server in a remote ANC system according to an exemplary embodiment of the present invention.

[0124] Reference Figure 7 , vehicle 510 compresses a multi-channel signal including at least one of a reference signal, a noise control signal, and an error signal for each channel using adaptive differential pulse code modulation (ADPCM) (S710). Here, the reference signal includes as many channels as the number (e.g., R) of reference sensors 511 arranged in vehicle 510. Here, the noise control signal includes as many channels as the number (e.g., K) of speakers 513 arranged in vehicle 510. Here, the error signal includes as many channels as the number (e.g., M) of microphones 515 arranged in vehicle 510. That is, the multi-signal can include at least one of R reference channel signals, K noise control channel signals, and M error channel signals.

[0125] The vehicle constructs packets (S720) including signals compressed for each channel, corresponding channel information, and corresponding ADPCM state information, by each predetermined transmission unit. Here, the predetermined transmission unit refers to a preset number of ADPCM output samples per channel or a transmission period. Here, the channel information refers to channel identifier information assigned to distinguish each of at least one reference signal, at least one noise control signal, and at least one error signal. Here, the ADPCM state information is information managed within an ADPCM encoder included in the vehicle, and includes the value of the previous input sample for each transmission unit and the index of a table of quantization step sizes used when compressing the previous input sample.

[0126] The vehicle sends the constructed packets to the server (S730). The vehicle can send the constructed packets to the server using the User Datagram Protocol (UDP).

[0127] The server restores the signals compressed for each channel based on the received packets (S740). The server can parse the received packets to extract the channel information, ADPCM state information, and ADPCM output samples for each channel. Thereafter, the server can restore the compressed signals of the channels based on the channel information and ADPCM state information extracted for each channel.

[0128] The server can further perform a process of updating the filter coefficients of the remote adaptive filter 423 using the restored signals. The server can further include a process of sending the updated filter coefficients to the vehicle.

[0129] Various embodiments of the systems and techniques described herein can be implemented by digital electronic circuitry, integrated circuits, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include those implemented in one or more computer programs executable on a programmable system. The programmable system includes at least one programmable processor (which can be a dedicated processor or a general-purpose processor), the at least one programmable processor being coupled to receive data and instructions from, and to send data and instructions to, a storage system, at least one input device, and at least one output device. A computer program (also referred to as a program, software, software application, or code) includes instructions for a programmable processor and is stored on a "computer-readable recording medium".

[0130] A computer-readable storage medium includes all types of storage devices that store data readable by a computer system. The computer-readable storage medium may include non-volatile or non-transitory media, such as ROM, CD-ROM, magnetic tapes, floppy disks, memory cards, hard disks, magneto-optical disks, and storage devices, and may further include transitory media, such as data transmission media. In addition, the computer-readable storage medium may be distributed in computer systems connected by a network and may store and execute computer-readable code in a distributed manner.

[0131] In the flowcharts of this specification, each process is described as occurring in sequence, but this is merely an example of the technology of the exemplary embodiments of the present invention. In other words, those of ordinary skill in the art to which the exemplary embodiments of the present invention pertain can make various modifications and variations by changing the order described in the flowcharts of this specification or by executing one or more processes in parallel within the basic features of the exemplary embodiments of the present invention. Therefore, the flowcharts of this specification are not limited to the time-series order.

[0132] In addition, terms related to control devices such as "controller", "control device", "control unit", "control apparatus", "control module", "control circuit", or "server" refer to hardware devices that include a memory and a processor (configured to execute one or more steps interpreted as algorithmic structures). The memory stores algorithmic steps, and the processor executes the algorithmic steps to perform one or more processes of the method according to various exemplary embodiments of the present invention. The control device according to the exemplary embodiments of the present invention can be implemented by a non-volatile memory and a processor, the non-volatile memory being configured to store algorithms for controlling the operations of various components of a vehicle or data of software instructions for executing the algorithms, the processor being configured to perform the above operations using the data stored in the memory. The memory and the processor may be separate chips. Alternatively, the memory and the processor may be integrated in a single chip. The processor may be implemented as one or more processors. The processor may include various logic circuits and operation circuits, may be configured to process data according to a program provided by the memory, and may be configured to generate control signals according to the processing results.

[0133] The control device may be at least one microprocessor operated by a predetermined program, and the predetermined program may include a series of instructions for performing the methods of the above various exemplary embodiments of the present invention.

[0134] The above invention may also be embodied as computer-readable code on a computer-readable recording medium. A computer-readable recording medium is any data storage device that can store data that can be subsequently read by a computer system and store and execute program instructions that can be subsequently read by a computer system. Examples of computer-readable recording media include hard disk drives (HDDs), solid state drives (SSDs), silicon disk drives (SDDs), read-only memories (ROMs), random access memories (RAMs), CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, etc., as well as implementations using carrier waves (e.g., transmission via the Internet). Examples of program instructions include machine language code, such as code generated by a compiler, and high-level language code that can be executed by a computer using an interpreter, and so on.

[0135] In various exemplary embodiments of the present invention, each of the above operations may be performed by a control device, and the control device may be configured by a plurality of control devices or an integrated single control device.

[0136] In various exemplary embodiments of the present invention, the memory and the processor may be provided as one chip, or provided as separate chips.

[0137] In various exemplary embodiments of the present invention, the scope of the present invention includes software or machine-executable instructions (e.g., operating systems, applications, firmware, programs, etc.) for enabling the operations of the methods according to the various embodiments to be performed on a device or computer, and non-volatile computer-readable media including such software or commands stored thereon and executable on the device or computer.

[0138] In various exemplary embodiments of the present invention, the control device may be implemented in the form of hardware or software, or may be implemented as a combination of hardware and software.

[0139] In addition, terms such as "unit", "module", etc. included in the specification represent units for processing at least one function or operation, which may be implemented by hardware, software, or a combination thereof.

[0140] In the flowcharts described with reference to the accompanying drawings, the flowcharts may be executed by a controller or a processor. The order of the steps in the flowcharts may be changed, multiple steps may be combined, any step may be split, and a predetermined step may not be executed. In addition, the steps in the flowcharts may be executed in sequence, but not necessarily in sequence. For example, the order of the steps may be changed, and at least two steps may be executed in parallel.

[0141] Hereinafter, the fact that parts of the hardware are operably coupled may include that a direct and / or indirect connection is established between the parts of the hardware by wired and / or wireless means.

[0142] In an exemplary embodiment of the present invention, a vehicle may be referred to based on a concept including various transportation means. In some cases, a vehicle may be interpreted based on a concept including not only various land transportation means such as cars, motorcycles, trucks, and buses that travel on roads, but also various transportation means such as airplanes, drones, ships, etc.

[0143] For the convenience of explanation and to accurately define the appended claims, the terms "upper", "lower", "inner", "outer", "above", "below", "upward", "downward", "front", "rear", "rear portion", "inner side", "outer side", "inward", "outward", "internal", "external", "inner side", "outer side", "forward", and "backward" are used to describe the features of the exemplary embodiments with reference to the positions of these features shown in the drawings. It will be further understood that the term "connected" or its derivatives refer to both direct connection and indirect connection.

[0144] The term "and / or" may include a combination of multiple related listed items or any one of the multiple related listed items. For example, "A and / or B" includes three cases, namely "A", "B", and "A and B".

[0145] In an exemplary embodiment of the present invention, "at least one of A and B" may refer to "at least one of A or B" or "at least one of a combination of at least one of A and B". In addition, "one or more of A and B" may refer to "one or more of A or B" or "one or more of a combination of one or more of A and B".

[0146] In this specification, unless the context clearly indicates otherwise, a singular expression includes a plural expression.

[0147] In an exemplary embodiment of the present invention, it should be understood that terms such as "including" or "having" are intended to indicate the presence of the features, numerical values, steps, operations, elements, components, or combinations thereof described in the specification, and do not exclude the possibility of adding or existing one or more other features, numerical values, steps, operations, elements, components, or combinations thereof.

[0148] According to an exemplary embodiment of the present invention, components may be combined with each other to be implemented as one, or some components may be omitted.

[0149] For purposes of illustration and description, the foregoing description of specific exemplary embodiments of the invention has been presented. The foregoing description is not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above disclosure. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application so as to enable others skilled in the art to make and utilize various exemplary embodiments of the invention, as well as its different alternative and modified embodiments. The scope of the invention is intended to be defined by the appended claims and their equivalents.

Claims

1. A method for transmitting and receiving multi-channel signals between a vehicle and a server in a remote active noise control system, the method comprising: compressing, by at least one processor of the vehicle, for each channel, a multi-channel signal using adaptive differential pulse code modulation, the multi-channel signal comprising at least one reference signal, at least one noise control signal, and at least one error signal; By at least one processor of the vehicle, constructing a packet per predetermined transmission unit, the packet including a signal compressed for each channel, corresponding channel information, and corresponding adaptive differential pulse code modulation state information; sending, by at least one processor of the vehicle, the constructed packet to a server; The compressed signal for each channel is restored based on the received packets by the server.

2. The method according to claim 1, wherein: The predetermined transmission unit is a preset number of adaptive differential pulse code modulation output samples or a preset transmission period of each channel.

3. The method according to claim 1, wherein: The channel information is channel identifier information allocated to distinguish at least one reference signal, at least one noise control signal, and at least one error signal.

4. The method according to claim 1, wherein: The ADPCM state information is information managed within an ADPCM encoder included in a vehicle and includes a value of a previous input sample per transmission unit and an index to a table of quantization step sizes used when compressing the previous input sample.

5. The method according to claim 1, wherein: The constructed packet is sent to the server using the User Datagram Protocol.

6. The method according to claim 1, wherein: Restoring the compressed signal for each channel involves: parsing, by the server, received packets to extract, for each channel, channel information, adaptive differential pulse code modulation state information, and adaptive differential pulse code modulation output samples; The corresponding compressed signal of the channel is restored by the server based on the channel information and the adaptive differential pulse code modulation state information extracted for each channel.

7. The method according to claim 1, further comprising: updating, by the server, filter coefficients of a remote adaptive filter using the recovered signal; The updated filter coefficients are sent to the vehicle via the server.

8. An apparatus for transmitting a multi-channel signal included in a vehicle in a remote active noise control system, the apparatus comprising: a memory configured to store instructions; and at least one processor, wherein the at least one processor executes the instructions to: compressing a multi-channel signal for each channel using adaptive differential pulse code modulation, the multi-channel signal comprising at least one reference signal, at least one noise control signal, and at least one error signal; Constructing a packet per predetermined transmission unit, the packet including a signal compressed for each channel, corresponding channel information, and corresponding adaptive differential pulse code modulation state information; Send the constructed group to the server.

9. The apparatus for transmitting a multi-channel signal included in a vehicle in a remote active noise control system according to claim 8, wherein: The predetermined transmission unit is a preset number of adaptive differential pulse code modulation output samples or a preset transmission period of each channel.

10. The apparatus for transmitting a multi-channel signal included in a vehicle in a remote active noise control system according to claim 8, wherein: The channel information is channel identifier information allocated to distinguish at least one reference signal, at least one noise control signal, and at least one error signal.

11. The apparatus for transmitting a multi-channel signal included in a vehicle in a remote active noise control system according to claim 8, wherein: The ADPCM state information is information managed within an ADPCM encoder included in a vehicle and includes a value of a previous input sample per transmission unit and an index to a table of quantization step sizes used when compressing the previous input sample.

12. The apparatus for transmitting a multi-channel signal included in a vehicle in a remote active noise control system according to claim 8, wherein: The constructed packet is sent to the server using the User Datagram Protocol.

13. An apparatus for receiving a multi-channel signal included in a service in a remote active noise control system, the apparatus comprising: a memory configured to store instructions; and at least one processor, wherein the at least one processor executes the instructions to: receiving a packet from at least one vehicle; The signal compressed for each channel is restored based on the received packets.

14. The apparatus for receiving a multi-channel signal included in a service in a remote active noise control system according to claim 13, wherein: The at least one processor is further configured to: parsing the received packets to extract channel information, adaptive differential pulse code modulation state information, and adaptive differential pulse code modulation output samples for each channel; A corresponding compressed signal of the channel is restored based on the extracted channel information and adaptive differential pulse code modulation state information for each channel.

15. The apparatus for receiving a multi-channel signal included in a service in a remote active noise control system according to claim 13, wherein: The at least one processor is further configured to: using the recovered signal to update filter coefficients of the remote adaptive filter; The updated filter coefficients are transmitted to corresponding vehicles of the at least one vehicle.

16. The apparatus for receiving a multi-channel signal included in a service in a remote active noise control system according to claim 14, wherein: The channel information is channel identifier information allocated to distinguish at least one reference signal, at least one noise control signal, and at least one error signal of a multi-channel signal.

17. The apparatus for receiving a multi-channel signal included in a service in a remote active noise control system according to claim 14, wherein: The ADPCM state information is information managed within an ADPCM encoder included in at least one vehicle and includes a value of a previous input sample of each transmission unit and an index to a table of quantization step sizes used when compressing the previous input sample.

18. The apparatus for receiving a multi-channel signal included in a service in a remote active noise control system according to claim 14, wherein: Each packet of each predetermined transmission unit is transmitted from at least one vehicle to a server using a user datagram protocol, the packet including a signal compressed for each channel, corresponding channel information, and corresponding adaptive differential pulse code modulation state information.

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