True wireless stereo lossless audio transmission system and method based on ultra wide band

Abstract

The invention belongs to the technical field of wireless communication, and discloses a true wireless stereo lossless audio transmission system and method based on an ultra wide band. According to the system, high-bandwidth and low-delay lossless audio transmission is realized by using an ultra wide band (UWB) technology, and the defects of the traditional Bluetooth technology in tone quality, synchronization precision and anti-interference capability are overcome. The transmission method in the system comprises the steps of lossless audio coding and decoding and bandwidth adaptation, binaural independent transmission and precise synchronization, self-adaptive frequency hopping anti-interference and power consumption optimization. The high bandwidth characteristic of the UWB technology is utilized, lossless audio transmission of 24 bit / 48 kHz and above is supported, the end-to-end delay is smaller than 10 ms, the left and right ear synchronization error is smaller than 10 us, and the power consumption is reduced through hierarchical wake-up and discontinuous transmission mechanisms. The system is suitable for a true wireless stereo audio transmission scene with high sound quality and low delay, and has the characteristics of excellent anti-interference capability and low power consumption.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication, in particular to a true wireless stereo lossless audio transmission system and method based on ultra-wideband. BACKGROUND

[0002] Bluetooth audio transmission is a common audio transmission method, however, Bluetooth audio transmission often uses SBC / AAC / LDAC lossy encoding, which cannot support lossless audio transmission; at the same time, it also has limitations on bandwidth, and the most advanced Bluetooth technology can achieve a data rate of 990 lbps, but it is difficult to meet the demand of lossless audio transmission for data rate; Bluetooth left and right earphone synchronization under the master-slave architecture depends on protocol stack optimization, which is easy to be disturbed by the environment, resulting in sound field deviation, thereby causing low synchronization accuracy; Bluetooth is crowded in the 2.4GHz frequency band, and is easy to be disturbed by Wi-Fi, microwave oven and other devices.

[0003] UWB technology is a technology with high bandwidth, low delay and high anti-interference, which can realize lossless transmission of audio, however, there are the following problems in applying UWB technology to audio transmission: UWB is traditionally used in positioning scenarios, and continuous transmission of high-bandwidth audio needs to reduce optimized power consumption; precise time synchronization and independent data transmission of left and right earphones need to be realized; high code rate of lossless audio needs to optimize encoding and decoding.

[0004] In view of the above problems, the present application provides a true wireless stereo lossless audio transmission system and method based on ultra-wideband. SUMMARY

[0005] The present application aims to provide a true wireless stereo lossless audio transmission system and method based on ultra-wideband to solve the problems of existing Bluetooth technology in high sound quality, low delay and anti-interference ability.

[0006] In order to achieve the above purpose, the present application provides the following technical scheme:

[0007] A true wireless stereo lossless audio transmission method based on ultra-wideband, including lossless audio encoding and decoding and bandwidth adaptation: the lossless audio encoding uses one of ADPCM, WAV, FLAC and SCL6 lossless compression algorithms, and realizes lossless transmission in combination with the high bandwidth characteristics of UWB; the bandwidth adaptation adjusts the encoding code rate in real time according to the UWB channel quality, supports ultra-high-definition lossless mode (greater than 10Mbps, supports video transmission; greater than 2Mbps and less than 10Mbps, supports lossless audio transmission; less than 1Mbps, supports high-definition voice conversation);

[0008] Binaural independent transmission and precise synchronization: Binaural transmission sends independent audio streams to left and right earbuds simultaneously; Precise synchronization is a synchronization mechanism based on UWB timestamp, which aligns left and right ear data packets using UWB nanosecond-level timestamp, achieving <10us synchronization error.

[0009] Adaptive frame skipping and anti-interference: Adaptive frame skipping dynamically selects UWB sub-band to avoid Wi-Fi 6E band interference; Real-time frequency hopping strategy based on channel state information ensures transmission stability.

[0010] Power consumption optimization: including hierarchical wake-up mechanism and discontinuous transmission mechanism, hierarchical wake-up mechanism wakes up UWB radio module only when audio data arrives; Discontinuous transmission utilizes UWB pulse characteristics to reduce average power consumption through burst transmission.

[0011] Further, the implementation steps of binaural independent transmission and precise synchronization are:

[0012] S1, the audio source device broadcasts a UWB synchronization beacon containing a global clock reference;

[0013] S2, after receiving the beacon, the left and right earbuds calibrate the local clock, and the local clock error is <100ns;

[0014] S3, audio data is transmitted in time, and the left and right earbuds independently analyze the audio stream according to the timestamp.

[0015] Further, the anti-interference method is specifically: dynamic spectrum sensing, UWB receiver monitors channel interference energy in real time, triggers frequency hopping to idle sub-band; Forward error correction, using Reed-solomon encoding to correct burst errors.

[0016] Further, the power consumption optimization method is specifically: data prefetch buffer, earbud UWB module wakes up every 100ms, receives 1 second of audio data in batches and then goes to sleep; Inter-earbud cooperation, the main earbud forwards time synchronization information to the secondary earbud through near-field magnetic induction, reducing the number of UWB activations.

[0017] A true wireless stereo lossless audio transmission system based on ultra-wideband, characterized in that the sending end and receiving end in the system use the above audio transmission method.

[0018] Further, the system hardware audio source device integrates a UWB transmission module, including one of Qorvo DW3000, NXPSR150, and SPARK SR1020.

[0019] Further, the transmission layer in the software protocol stack in the system adopts a self-defined protocol frame structure, including a timestamp field, an audio data block and a CRC check, wherein the timestamp field is 67 bits, used for binaural synchronization; the audio data block is 512 bytes, used for encapsulating the audio data after FLAC encoding; and the CRC check is 32 bits, used for cyclic redundancy check.

[0020] The beneficial effects of the technical solution are that the method can effectively improve the audio quality of transmission based on the ultra-wideband technology, can support lossless audio transmission, support 24bit / 48kHz and above lossless audio transmission, and the signal-to-noise ratio is >120dB; the end-to-end transmission delay is <10ms when the method is used for audio transmission, which is greatly improved compared with the typical value 20ms of the prior art Bluetooth LEAudio; the transmission method has strong anti-interference ability, and the bit error rate is <1e-6 in a Wi-Fi dense environment. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The figure is a transmission architecture diagram of the lossless UWB transmission system of the application;

[0022] Figure 2 The figure is a protocol stack control diagram in the lossless UWB transmission system of the application;

[0023] Figure 3 The figure is a transmission method strategy diagram in the lossless UWB transmission system of the application; DETAILED DESCRIPTION

[0024] The application will be further described in detail below in combination with the drawings and embodiments:

[0025] A true wireless stereo lossless audio transmission system based on ultra-wideband. The audio source device in the hardware of the system is a sending end, the audio source device integrates a UWB transmission module conforming to the FiRa specification and the IEEE 802.15.4z standard, for example: Qorvo DW3000, which supports multi-channel audio outflow. For example, Figure 1 The figure is a transmission architecture diagram of the transmission system of the application;

[0026] The hardware part TWS earplug in the system is a receiving end, the TWS earplug contains a UWB receiving module, a special audio DSP chip and a low-power microcontroller, the UWB receiving module is compatible with the IEEE 802.15.4z standard. The special audio DSP chip is Cirrus Logic CS47L35, and the special audio DSP chip is used for realizing real-time lossless decoding. The low-power microcontroller is Nordic nRF5340, and the low-power microcontroller is used for managing the UWB protocol stack.

[0027] For example, Figure 2The protocol stack control diagram in the system of the application is shown in the figure:

[0028] The physical layer of the software protocol stack in the system adopts HRP (High Rate Pulse) UWB mode, supporting a data rate of 6.8 Mbps. The electromagnetic wave frequency range is 3.1-10.6 GHz super high frequency band, achieving nanoscale synchronization accuracy.

[0029] The transmission layer of the software protocol stack in the system adopts a self-defined protocol frame structure, including a timestamp field, an audio data block and a CRC check. The timestamp field is 64 bits, and the timestamp field is used for binaural synchronization; the audio data block is 512 bytes, and the audio data block is used for encapsulating FLAC encoded audio data; and the CRC check section is 32 bits, and the CRC check section is used for 32-bit cyclic redundancy check.

[0030] The application layer of the system supports a compatible interface of LDAC / LHDC high-definition audio encoding format.

[0031] The lossless audio encoding in the system adopts an ADPCM lossless compression algorithm, which realizes lossless transmission by combining the UWB high bandwidth characteristics; the bandwidth adaptation adjusts the encoding code rate in real time according to the UWB channel quality, and the bandwidth adaptation adjusts the encoding code rate in real time according to the UWB channel quality, which is greater than 10 Mbps, supporting video transmission; greater than 2 Mbps and less than 10 Mbps, supporting lossless audio transmission; less than 1 Mbps, supporting high-definition voice conversation.

[0032] As shown in the figure, Figure 3 The audio transmission method strategy diagram in the system of the application is shown in the figure;

[0033] The audio source device sending end and the TWS earplug receiving end in the system both adopt the following method for audio transmission: during the audio transmission process, independent transmission and accurate synchronization of both ears are adopted; S1, the audio source device broadcasts a UWB synchronization beacon, containing a global clock reference; S2, after the left and right earplugs receive the beacon, the local clock is calibrated, and the local clock error is less than 100 ns; S3, audio data is transmitted in time, and the left and right earplugs independently analyze the audio stream according to the timestamp.

[0034] The anti-interference method adopted in the system is: dynamic spectrum sensing, the UWB receiving end monitors the channel interference energy in real time, triggers frequency hopping to the idle sub-band; forward error correction, Reed-solomon encoding is adopted to correct burst errors.

[0035] The power consumption optimization method adopted in the system is: data prefetching buffer, the earplug UWB module wakes up once every 100 ms, and after receiving 1 second of audio data in batches, it enters sleep; earplug cooperation, the main earplug forwards time synchronization information to the auxiliary earplug through near-field magnetic induction, reducing the number of UWB activations.

[0036] The system is tested and verified, and the audio transmitted by the audio source is received by the TWS earplug. The sound quality in the test result is verified by the APx555 audio analyzer, and the THD+N of the sound quality is less than 0.0005%. The delay error of the left and right channels is measured by an oscilloscope, and the delay error of the left and right channels is less than 15us.

[0037] From the above results, the system for transmitting audio using the method of the application can realize high-quality lossless audio transmission, effectively reduce the end-to-end transmission delay, and also has strong anti-interference ability.

[0038] The above is only an embodiment of the application, and well-known specific technical solutions or characteristics in the scheme are not described in detail. For those skilled in the art, without departing from the technical solutions of the application, a number of modifications and improvements can be made, which should also be considered as the protection scope of the application, and these will not affect the effect and practicality of the application. The protection scope of the present application shall be subject to the content of its claims, and the specific embodiments and the like in the specification can be used to explain the content of the claims.

Claims

1. A true wireless stereo lossless audio transmission method based on ultra-wideband, characterized in that: Includes lossless audio codec and broadband adaptation: Lossless audio coding uses a lossless compression algorithm among ADPCM, WAV, FLAC and SCL6, combined with the high bandwidth characteristics of UWB to achieve lossless transmission; bandwidth adaptation adjusts the encoding bit rate in real time according to the UWB channel quality, with a bit rate greater than 10Mbps to support video transmission; greater than 2Mbps and less than 10Mbps to support lossless audio transmission; less than 1Mbps to support high-definition voice conversations; Binaural independent transmission and precise synchronization: Binaural transmission means the audio device sends independent audio streams to the left and right earbuds simultaneously. Precise synchronization is a synchronization mechanism based on UWB timestamps, which uses UWB's nanosecond timestamps to align the left and right ear data packets, achieving a synchronization error of less than 10us. Adaptive frame hopping and anti-interference: Adaptive frame hopping dynamically selects UWB sub-bands to avoid interference from the Wi-Fi 6E band. A real-time frequency hopping strategy based on channel state information ensures transmission stability. Power consumption optimization: This includes a hierarchical wake-up mechanism and a discontinuous transmission mechanism. The hierarchical wake-up mechanism wakes up the UWB radio module only before audio data arrives; the discontinuous transmission utilizes the UWB pulse characteristics and reduces average power consumption through burst transmission.

2. The method for true wireless stereo lossless audio transmission based on ultra-wideband according to claim 1, wherein: The steps for implementing binaural independent transmission and precise synchronization are as follows: S1. The audio source device broadcasts a UWB synchronization beacon, which contains a global clock reference. S2. After receiving the beacon, the left and right earbuds calibrate the local clocks, and the local clock error is less than 100ns. S3. Audio data is transmitted in time-sharing mode, and the left and right earbuds independently parse the audio stream based on the timestamp.

3. The method for true wireless stereo lossless audio transmission based on ultra-wideband according to claim 1, characterized in that: The anti-interference method specifically includes: dynamic spectrum sensing, where the UWB receiver monitors the channel interference energy in real time and triggers frequency hopping to an idle sub-band; and forward error correction, which uses Reed-Solomon coding to correct sudden bit errors.

4. The method for true wireless stereo lossless audio transmission based on ultra-wideband according to claim 1, wherein: The power consumption optimization method is specifically as follows: data pre-fetch buffering, the earbud UWB module wakes up every 100ms, and enters sleep after receiving 1 second of audio data in batches; The earbuds collaborate with each other, with the main earbud forwarding time synchronization information to the secondary earbud through near-field magnetic induction, reducing the number of UWB activations.

5. A true wireless stereo lossless audio transmission system based on ultra-wideband, characterized in that: The transmitting end and the receiving end in the system adopt the audio transmission method according to any one of claims 1 to 4.

6. The ultra-wideband true wireless stereo lossless audio transmission system according to claim 5, characterized in that: The system's hardware audio source device integrates a UWB transmitter module, including one of Qorvo DW3000, NXP SR150, and SPARKSR1020.

7. The ultra-wideband-based true wireless stereo lossless audio transmission system according to claim 5, characterized in that: The transport layer in the software protocol stack of this system uses a custom protocol frame structure, including a timestamp field, an audio data block, and a CRC checksum. The timestamp field is 67 bits and is used for binaural synchronization. The audio data block is 512 bytes and is used to encapsulate FLAC-encoded audio data. CRC check 32 bits, used for cyclic redundancy check.

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