Method for transmitting multi-channel audio signal by using bluetooth low energy (LE) technology, and device therefor

Abstract

A method for operating an electronic device in a short-range wireless communication system, according to an embodiment of the present specification, comprises the steps of: transmitting an audio signal for a plurality of speakers; receiving, from the plurality of speakers, information related to a channel state for the audio signal; determining a channel for transmitting the audio signal on the basis of the information; and transmitting the audio signal according to the determined channel. The information includes individual information related to a channel state for the audio signal of each of the plurality of speakers.

Description

Method and device for transmitting multi-channel audio signals using Bluetooth LE (LOW ENERGY) technology

[0001] The present specification relates to a method and a device for transmitting a multi-channel audio signal using Bluetooth LE (Bluetooth Low Energy, BLE) technology, and more specifically, to a method and a device for receiving channel states from a plurality of audio receiving devices in a multi-channel audio transmission environment using BLE technology, and transmitting audio signals through a channel in a good state to the plurality of audio receiving devices based thereon.

[0002] Bluetooth is a short-range wireless communication technology developed to support two-way communication between various portable electronic devices, including personal digital assistants, mobile phones, laptops, and computers. Bluetooth technology primarily uses the 2.4 GHz frequency band for wireless communication, enabling data transmission with relatively low power consumption. Initially used primarily as a cable replacement, it has now expanded into diverse applications, including audio streaming, data synchronization, and device control.

[0003] BLE (Bluetooth Low Energy) is a low-power wireless communication technology that offers short-range wireless communication capabilities while consuming significantly less power than conventional Bluetooth. BLE is particularly suited for applications requiring low data rates and long battery life, such as battery-powered devices, Internet of Things (IoT) devices, and wearables.

[0004] BLE is optimized for intermittent data transmission, activating only for brief periods to transmit data before transitioning back to low-power standby mode. Furthermore, BLE maximizes energy efficiency by offering a streamlined protocol stack and faster connection setup times.

[0005] Existing Bluetooth audio connection technology was developed primarily to transmit stereo (2-channel) audio signals. It is used to wirelessly stream high-quality stereo audio from audio source devices such as smartphones, tablets, computers, and TVs to audio sink (receiving) devices such as Bluetooth earphones, headphones, and speakers.

[0006] Conventional 2-channel Bluetooth audio connections are typically based on a 1:1 connection, with one audio source device transmitting stereo audio to one audio receiver device.

[0007] Meanwhile, a method for transmitting multichannel audio beyond two channels using BLE is defined. For example, multichannel audio signals can be transmitted to multiple audio receiving devices based on BIS (Broadcast Isochronous Stream).

[0008] Existing Bluetooth audio transmission technology is primarily limited to stereo (2-channel) transmission, limiting the implementation of multi-channel surround sound using multiple speakers. Furthermore, for multi-channel connections of four or more channels, non-standard technologies like Wi-Fi are used instead of Bluetooth, limiting compatibility.

[0009] Accordingly, research is being conducted to implement multi-channel surround audio via Bluetooth connection. When using multi-channel, when transmitting audio signals based on BIS (Broadcast Isochronous Stream) for each channel, the channel condition may not be good due to interference from surrounding Bluetooth devices or Wi-Fi devices, but there is a problem in that the source device transmitting the audio signal based on the broadcast method cannot know the channel condition of each of the multiple audio receiving devices.

[0010] The purpose of this specification is to propose a method for receiving channel status from each of a plurality of audio receiving devices when a BIS-based audio signal is transmitted, and transmitting an audio signal to a good channel for the plurality of audio receiving devices based thereon, in order to solve the above-described problem.

[0011] The technical problems to be achieved in this specification are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0012] In order to solve the above-described technical problem, a method according to one embodiment of the present specification includes the steps of transmitting an audio signal to a plurality of speakers, receiving information related to a channel state for the audio signal from the plurality of speakers, determining a channel for transmitting the audio signal based on the information, and transmitting the audio signal based on the determined channel. At this time, the information includes individual information related to the channel state for the audio signal for each of the plurality of speakers.

[0013] The above audio signal can be transmitted to the plurality of speakers in a broadcast manner.

[0014] The above audio signal includes a plurality of sub audio signals associated with each of the plurality of speakers, and the individual information may be related to a channel state for each of the sub audio signals of the plurality of speakers.

[0015] The above audio signal is transmitted according to an ISO interval based on an ISO channel (Isochronous channel), and the ISO interval includes a plurality of sub-intervals corresponding one-to-one with the plurality of sub-audio signals, and each of the plurality of sub-audio signals can be transmitted according to a corresponding sub-interval.

[0016] The above ISO interval may further include a section in which the above information is received.

[0017] The above information can be received based on asynchronous connection-oriented logical transport (ACL).

[0018] The above ACL may be related to volume control.

[0019] The step of receiving the above information from the plurality of speakers may include the step of transmitting periodic advertising to the plurality of speakers and the step of receiving a plurality of responses based on the periodic advertising from the plurality of speakers.

[0020] The above plurality of responses correspond one-to-one with the plurality of speakers, and each of the above plurality of responses may include the individual information of the corresponding speaker.

[0021] The above multiple responses can be received through contiguous slots.

[0022] A method according to another embodiment of the present disclosure includes the steps of receiving an audio signal from an electronic device, transmitting individual information related to a channel state for the audio signal to the electronic device, and receiving the audio signal from the electronic device based on a channel determined based on information related to the channel state for the audio signal of the plurality of speakers. In this case, the information includes the individual information related to the channel state for the audio signal of each of the plurality of speakers.

[0023] The above audio signal can be received in a broadcast manner.

[0024] The above audio signal includes a plurality of sub audio signals associated with each of the plurality of speakers, and the individual information may be related to a channel state for each of the sub audio signals of the plurality of speakers.

[0025] The above audio signal is received according to an ISO interval based on an ISO channel (Isochronous channel), and the ISO interval includes a plurality of sub-intervals corresponding one-to-one with the plurality of sub-audio signals, and each of the plurality of sub-audio signals can be received according to a corresponding sub-interval.

[0026] The above ISO interval may further include a section in which the above information is transmitted.

[0027] The above information can be transmitted based on asynchronous connection-oriented logical transport (ACL).

[0028] The above ACL may be related to volume control.

[0029] The step of transmitting the individual information to the electronic device may include the step of receiving periodic advertising from the electronic device and the step of transmitting a response based on the periodic advertising to the electronic device.

[0030] The above response may include the individual information of the above speaker.

[0031] The plurality of responses corresponding one-to-one with the plurality of speakers can be transmitted through contiguous slots.

[0032] According to another embodiment of the present disclosure, an electronic device includes one or more transceivers, one or more processors, and one or more memories storing instructions that perform operations based on instructions executed by the one or more processors. The operations include: transmitting an audio signal to a plurality of speakers; receiving information related to a channel state for the audio signal from the plurality of speakers; determining a channel for transmitting the audio signal based on the information; and transmitting the audio signal according to the determined channel. In this case, the information includes individual information related to a channel state for the audio signal for each of the plurality of speakers.

[0033] According to the operation according to the prior art, in a multi-channel audio transmission environment, when transmitting audio signals based on BIS (Broadcast Isochronous Stream) for each channel, there is a limitation that the source device cannot know the channel status of each of the multiple audio receiving devices when the channel status is not good due to interference from surrounding devices.

[0034] According to the embodiment of the present specification, a multi-channel audio transmission system is implemented using Bluetooth standard technology, thereby enabling compatibility between various devices.

[0035] In addition, by receiving channel status from multiple audio receiving devices during BIS-based multi-channel audio transmission and transmitting audio signals through a good channel based on the channel status, a realistic multi-channel surround audio environment can be provided.

[0036] The effects that can be obtained from this specification are not limited to the effects mentioned above, and other effects that are not mentioned can be clearly understood by those skilled in the art to which the present invention pertains from the description below.

[0037] The accompanying drawings are intended to aid in understanding the present disclosure and, together with detailed descriptions, may provide embodiments of the present disclosure. However, the technical features of the present disclosure are not limited to specific drawings, and the features disclosed in each drawing may be combined with each other to form new embodiments. Reference numerals in each drawing may indicate structural elements.

[0038] Figure 1 is a schematic diagram showing an example of a wireless communication system using the Bluetooth low energy technology proposed in this specification.

[0039] FIG. 2 shows an example of an internal block diagram of a device capable of implementing the methods proposed in this specification.

[0040] Figure 3 shows an example of a Bluetooth communication architecture to which the methods proposed in this specification can be applied.

[0041] Figure 4 shows an example of the structure of the GATT (Generic Attribute Profile) of Bluetooth low energy.

[0042] FIG. 5 is a flowchart illustrating an example of a connection procedure method in Bluetooth low energy technology to which embodiments of the present specification can be applied.

[0043] FIG. 6 illustrates an example of a system structure in which multi-channel audio signals are transmitted between a BLE-based TV transmitting device and multiple BLE audio receiving speakers.

[0044] Figure 7 illustrates an example of a compensation procedure for synchronizing video processing delay and audio processing delay in a Bluetooth low-latency audio system.

[0045] FIG. 8 illustrates an example of a test stream-based calibration procedure for measuring and adjusting the sound pressure level of each speaker relative to a user's position in a BLE-based audio system.

[0046] FIG. 9 illustrates an example of an inter-speaker synchronization correction structure for correcting sound synchronization errors due to distance differences between front and rear speakers in a multi-channel audio system.

[0047] Fig. 10 illustrates an example of an inter-speaker synchronization correction structure for correcting sound synchronization errors due to distance differences between rear speakers in a multi-channel audio system.

[0048] Figure 11 illustrates an example of an overall system configuration for multi-channel audio transmission between a BLE-based TV and multiple audio receiving devices and a profile structure based on Surround Sound Audio Profile (SSAP).

[0049] FIG. 12 illustrates an example of the configuration range and related specifications within a BLE audio system of the Surround Sound Audio Profile (SSAP) proposed in this specification.

[0050] Figure 13 illustrates an example of multi-channel transmission using Surround Sound Audio Profile (SSAP).

[0051] Figure 14 illustrates another example of multichannel transmission using Surround Sound Audio Profile (SSAP).

[0052] Figure 15 illustrates an example of a channel map update based on the channel status of multiple audio receiving devices in a BLE-based multi-channel transmission environment.

[0053] Figure 16 illustrates an example of a BLE ISO channel configuration method and a BIS unit multi-channel audio transmission structure based on the Surround Sound Audio Profile (SSAP).

[0054] Figure 17 illustrates an example of a channel state transmission / reception and channel map update procedure in multi-channel audio transmission based on one BIS.

[0055] Figure 18 illustrates an example of a channel state transmission / reception and channel map update procedure in multi-channel audio transmission based on multiple BISs.

[0056] Figure 19 illustrates an example of a channel state transmission and reception procedure of multiple speakers based on periodic BLE broadcasts and responses.

[0057] FIG. 20 is a flowchart illustrating a method according to one embodiment of the present specification.

[0058] FIG. 21 is a flowchart illustrating a method according to another embodiment of the present specification.

[0059] In various embodiments of the present disclosure, “A or B” may mean “only A,” “only B,” or “both A and B.” In other words, in various embodiments of the present disclosure, “A or B” may be interpreted as “A and / or B.” For example, in various embodiments of the present disclosure, “A, B or C” may mean “only A,” “only B,” “only C,” or “any combination of A, B and C.”

[0060] In various embodiments of the present disclosure, a slash ( / ) or a comma may mean "and / or." For example, "A / B" may mean "A and / or B." Accordingly, "A / B" may mean "only A," "only B," or "both A and B." For example, "A, B, C" may mean "A, B, or C."

[0061] In various embodiments of the present disclosure, “at least one of A and B” may mean “only A,” “only B,” or “both A and B.” Furthermore, in various embodiments of the present disclosure, the expressions “at least one of A or B” or “at least one of A and / or B” may be interpreted as equivalent to “at least one of A and B.”

[0062] Additionally, in various embodiments of the present disclosure, “at least one of A, B and C” can mean “only A,” “only B,” “only C,” or “any combination of A, B and C.” Additionally, “at least one of A, B or C” or “at least one of A, B and / or C” can mean “at least one of A, B and C.”

[0063] Figure 1 is a schematic diagram showing an example of a wireless communication system using the Bluetooth low energy technology proposed in this specification.

[0064] A wireless communication system (100) includes at least one server device (Server Device, 120) and at least one client device (Client Device, 110).

[0065] The server device and client device perform Bluetooth communication using Bluetooth Low Energy (BLE, hereinafter referred to as 'BLE' for convenience) technology.

[0066] First, BLE technology has a relatively small duty cycle compared to Bluetooth BR / EDR (Basic Rate / Enhanced Data Rate) technology, allows for low-cost production, and significantly reduces power consumption through low-speed data transmission rates, enabling operation for more than a year using a coin cell battery.

[0067] Additionally, BLE technology simplifies the connection process between devices and is designed to have a smaller packet size compared to Bluetooth BR / EDR technology.

[0068] In BLE technology, (1) the number of RF channels is 40, (2) the data transmission speed supports 1 Mbps, (3) the topology is a scatternet structure, (4) the latency is 3 ms, (5) the maximum current is 15 mA or less, (6) the output power is 10 mW (10 dBm) or less, and (7) it is mainly used in applications such as mobile phones, watches, sports, healthcare, sensors, and device control.

[0069] The server device (120) can operate as a client device in a relationship with other devices, and the client device can operate as a server device in a relationship with other devices. That is, in a BLE communication system, any one device can operate as a server device or a client device, and, if necessary, can operate as a server device and a client device simultaneously.

[0070] The above server device (120) may be expressed as a data service device, a client device, a slave device, a server, a conductor, a host device, a gateway, a sensing device, a monitoring device, a first device, a second device, etc.

[0071] The above client device (110) can be expressed as a server device (master device), a master, a client, a member, a sensor device, a sink device, a collector, a third device, a fourth device, etc.

[0072] The server device and the client device are the main components of the wireless communication system, and the wireless communication system may include other components in addition to the server device and the client device.

[0073] The above server device refers to a device that receives data from a client device and performs direct communication with the client device, thereby providing data to the client device through a response when receiving a data request from the client device.

[0074] Additionally, the server device sends a notification message and an indication message to the client device to provide data information to the client device. Additionally, when the server device transmits an indication message to the client device, it receives a confirmation message corresponding to the indication message from the client.

[0075] In addition, the server device can provide data information to a user through an output unit (Display Unit) or receive a request input from a user through an input unit (User Input Interface) in the process of transmitting and receiving notifications, instructions, and confirmation messages to and from a client device.

[0076] Additionally, the server device can read data from a memory unit or write new data to the memory unit during the process of transmitting and receiving messages with the client device.

[0077] Additionally, one server device can be connected to multiple client devices, and can easily reconnect (or connect) to the client devices by utilizing bonding information.

[0078] The above client device (120) refers to a device that requests data information and data transmission from a server device.

[0079] The client device receives data from the server device through a notification message, an instruction message, etc., and when receiving an instruction message from the server device, sends a confirmation message in response to the instruction message.

[0080] Likewise, the client device can provide information to the user through an output unit or receive input from the user through an input unit during the process of transmitting and receiving messages with the server device.

[0081] Additionally, the client device can read data from memory or write new data to the memory during the process of transmitting and receiving messages with the server device.

[0082] Hardware components such as the output section, input section, and memory of the above server device and client device will be examined in detail in Fig. 2.

[0083] Additionally, the wireless communication system can establish a Personal Area Network (PAN) via Bluetooth technology. For example, the wireless communication system can establish a private piconet between devices, enabling the quick and secure exchange of files, documents, and other information.

[0084] FIG. 2 shows an example of an internal block diagram of a device capable of implementing the methods proposed in this specification.

[0085] As illustrated in FIG. 2, the server device (110) includes an input unit (User Input Interface, 112), a power supply unit (Power Supply Unit, 113), a control unit (Control Unit, 114), a memory unit (Memory Unit, 115), a network interface (Network Interface, 116) including a Bluetooth interface, storage (Storage, 117), an output unit (Display Unit, 118), and a multimedia module (Multi Media Module, 119).

[0086] The input unit (User Input Interface, 112), power supply unit (Power Supply Unit, 113), control unit (Control Unit, 114), memory (Memory Unit, 115), network interface (Network Interface, 116) including Bluetooth interface, storage (Storage, 117), output unit (Display Unit, 118), and multimedia module (Multi media Module, 119) are functionally interconnected to perform the method proposed in this specification.

[0087] In addition, as illustrated in FIG. 2, the client devices (#1 and #2) (120) include an input unit (User Input Interface, 122), a power supply unit (Power Supply Unit, 123), a control unit (Control Unit, 124), a memory unit (Memory Unit, 125), a network interface (Network Interface, 126) including a Bluetooth interface, storage (Storage, 127), an output unit (Display Unit, 128), and a multimedia module (Multi media Module, 129).

[0088] The above input unit (User Input Interface, 122), power supply unit (Power Supply Unit, 123), control unit (Control Unit, 124), memory (Memory Unit, 125), network interface (Network Interface, 126) including Bluetooth interface, storage (Storage, 127), output unit (Display Unit, 128), and multimedia module (Multi media Module, 129) are functionally interconnected to perform the method proposed in this specification.

[0089] The above network interface (116, 126) refers to a unit (or module) that can transmit data, such as request / response, command, notification, instruction / confirmation messages, etc., between devices using Bluetooth technology.

[0090] The above memory (115, 125) is a unit implemented in various types of devices, and refers to a unit in which various types of data are stored. In addition, the storage (117, 127) refers to a unit that performs a function similar to memory.

[0091] The above control unit (114, 124) refers to a module that controls the overall operation of the server device (110) or client device (120), and controls to request transmission of a message to a network interface or to process a received message.

[0092] The above control unit (114, 124) may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, and / or a data processing device.

[0093] The above memory (115, 125) may include a ROM (read-only memory), a RAM (random access memory), a flash memory, a memory card, a storage medium, and / or other storage devices.

[0094] The above memory (115, 125) may be internal or external to the processor (114, 124) and may be connected to the processor (114, 124) by various well-known means.

[0095] The above output unit (118, 128) refers to a module for providing device status information and message exchange information to the user through a screen.

[0096] The above power supply unit (power supply unit, 113, 123) refers to a module that receives external power and internal power under the control of the control unit and supplies the power required for the operation of each component.

[0097] As discussed above, BLE technology has a small duty cycle and can significantly reduce power consumption through low data rates.

[0098] Figure 3 shows an example of a Bluetooth communication architecture to which the methods proposed in this specification can be applied.

[0099] Specifically, FIG. 3 shows an example of the architecture of Bluetooth LE (Low Energy).

[0100] As illustrated in FIG. 3, the BLE architecture includes a controller stack (Controller stackACK) operable to handle timing-critical wireless device interfaces and a host stack (Host stackACK) operable to handle high level data.

[0101] The above Controller stack may be referred to as a Controller, but to avoid confusion with the processor, which is an internal component of the device mentioned in FIG. 2 above, it will be referred to as a Controller stackACK hereinafter.

[0102] First, the controller stack may be implemented using a communication module that may include a Bluetooth radio, and a processor module that may include a processing device, such as a microprocessor.

[0103] The host stack can be implemented as part of an OS running on a processor module, or as an instantiation of a package on top of the OS.

[0104] In some cases, the controller stack and the host stack may operate or execute on the same processing device within a processor module.

[0105] The host stack includes GAP (Generic Access Profile, 310), GATT-based Profiles (320), GATT (Generic Attribute Profile, 330), ATT (Attribute Protocol, 340), SM (Security Manager, 350), and L2CAP (Logical Link Control and Adaptation Protocol, 360). However, the host stack is not limited to this and may include various protocols and profiles.

[0106] The host stack multiplexes various protocols, profiles, etc. provided above Bluetooth using L2CAP.

[0107] First, L2CAP (Logical Link Control and Adaptation Protocol,360) provides a single bidirectional channel for transmitting data to a specific protocol or profile.

[0108] L2CAP may be capable of multiplexing data between upper layer protocols, segmenting and reassembling packages, and managing multicast data transmission.

[0109] BLE uses three fixed channels (one for signaling CH, one for Security Manager, and one for Attribute protocol).

[0110] On the other hand, BR / EDR (Basic Rate / Enhanced Data Rate) uses dynamic channels and supports protocol service multiplexer, retransmission, streaming mode, etc.

[0111] SM (Security Manager, 350) is a protocol for authenticating devices and providing key distribution.

[0112] ATT (Attribute Protocol, 340) defines the rules for accessing data from other devices in a server-client architecture. ATT has six message types: Request, Response, Command, Notification, Indication, and Confirmation.

[0113] That is, ① Request and Response messages: The Request message is a message for requesting specific information from a client device to a server device, and the Response message is a response message to the Request message, and refers to a message transmitted from the server device to the client device.

[0114] ② Command message: A message sent from a client device to a server device to instruct a specific action command. The server device does not send a response to the Command message to the client device.

[0115] ③ Notification message: A message sent from a server device to a client device for notification of events, etc.; the client device does not send a confirmation message for the Notification message to the server device.

[0116] ④ Indication and Confirm messages: Messages sent from the server device to the client device for notification of events, etc. Unlike the Notification message, the client device sends a confirmation message for the Indication message to the server device.

[0117] GAP (Generic Access Profile) is a new layer implemented for BLE technology, which is used to control role selection for communication between BLE devices and how multi-profile operation occurs.

[0118] Additionally, GAP is primarily used in device discovery, connection creation, and security procedures, defines how to provide information to users, and defines the types of attributes as follows:

[0119] ① Service: Defines the basic operation of the device through a combination of data-related behaviors.

[0120] ② Include: Defines the relationship between services

[0121] ③ Characteristics: Data values ​​used in the service

[0122] ④ Behavior: Computer-readable format defined as UUID (Universal Unique Identifier, value type)

[0123] GATT-based Profiles are profiles that depend on GATT and are primarily applied to BLE devices. GATT-based Profiles include Battery, Time, FindMe, Proximity, Time, and Object Delivery Service. The specifics of GATT-based Profiles are as follows.

[0124] Battery: How to exchange battery information

[0125] Time: A method for exchanging time information

[0126] FindMe: Distance-based alarm service

[0127] Proximity: How to Exchange Battery Information

[0128] Time: A method for exchanging time information

[0129] GATT can function as a protocol that describes how ATT is used when composing services. For example, GATT can be used to specify how ATT attributes are grouped into services, and can be used to describe the features associated with services.

[0130] Therefore, GATT and ATT can use features to describe the state and services of a device, how features relate to each other, and how they are used.

[0131] The controller stack includes a physical layer (390), a link layer (380), and a host controller interface (370).

[0132] The physical layer (wireless transmission / reception module, 390) is a layer that transmits and receives 2.4 GHz wireless signals and uses GFSK (Gaussian Frequency Shift Keying) modulation and a frequency hopping technique consisting of 40 RF channels.

[0133] The link layer (380) transmits or receives Bluetooth packets.

[0134] Additionally, the link layer performs advertising and scanning functions using three advertising channels, then creates a connection between devices, and provides the ability to send and receive data packets of up to 42 bytes through 37 data channels.

[0135] HCI (Host Controller Interface) provides an interface between the Host stack and the Controller stack, allowing the Host stack to provide commands and data to the Controller stack, and allowing the Controller stack to provide events and data to the Host stack.

[0136] Below, we will briefly look at the procedures of Bluetooth Low Energy (BLE) technology.

[0137] BLE procedures can be divided into device filtering procedures, advertising procedures, scanning procedures, discovering procedures, and connecting procedures.

[0138] Device Filtering Procedure

[0139] Device filtering procedures are a way to reduce the number of devices that respond to requests, instructions, notifications, etc. in the controller stack.

[0140] When a request is received from any device, since it is unnecessary to respond to it, the controller stack can control the power consumption of the BLE controller stack by reducing the number of requests transmitted.

[0141] An advertising device or scanning device may perform the above device filtering procedure to limit the devices that receive advertising packets, scan requests, or connection requests.

[0142] Here, an advertising device refers to a device that transmits an advertising event, i.e., performs an advertisement, and is also expressed as an advertiser.

[0143] A scanning device is a device that performs scanning and transmits scan requests.

[0144] In BLE, when a scanning device receives some advertising packets from an advertising device, the scanning device must send a scan request to the advertising device.

[0145] However, if a device filtering procedure is used to make sending scan requests unnecessary, the scanning device may ignore advertising packets transmitted from the advertising device.

[0146] Device filtering procedures may also be used during the connection request process. If device filtering is used during the connection request process, the connection request is ignored, eliminating the need to send a response to the connection request.

[0147] Advertising Procedure

[0148] An advertising device performs an advertising procedure to perform a non-directional broadcast to devices within the area.

[0149] Here, non-directional broadcast refers to broadcast in all directions rather than broadcasting in a specific direction.

[0150] In contrast, a directional broadcast refers to a broadcast in a specific direction. A non-directional broadcast occurs without a connection procedure between an advertising device and a device in a listening (or listening) state (hereinafter referred to as a listening device).

[0151] The advertising process is used to establish a Bluetooth connection with a nearby initiating device.

[0152] Alternatively, the advertising procedure may be used to provide periodic broadcasts of user data to scanning devices listening on the advertising channel.

[0153] In the advertising process, all advertisements (or advertising events) are broadcast through the advertising physical channel.

[0154] Advertising devices can receive scan requests from listening devices that are listening to obtain additional user data from the advertising device. The advertising device transmits a response to the scan request to the device that sent the scan request over the same advertising physical channel as the advertising physical channel that received the scan request.

[0155] Broadcast user data sent as part of advertising packets is dynamic data, whereas scan response data is typically static data.

[0156] An advertising device can receive a connection request from an initiating device on an advertising (broadcast) physical channel. If the advertising device uses a connectable advertising event and the initiating device is not filtered by the device filtering procedure, the advertising device stops advertising and enters connected mode. The advertising device can resume advertising after entering connected mode.

[0157] Scanning Procedure

[0158] A device performing scanning, i.e., a scanning device, performs a scanning procedure to listen for non-directional broadcasts of user data from advertising devices using an advertising physical channel.

[0159] The scanning device transmits a scan request to the advertising device via the advertising physical channel to request additional data from the advertising device. The advertising device transmits a scan response, which is a response to the scan request, including the additional data requested from the scanning device via the advertising physical channel.

[0160] The above scanning procedure can be used while connecting with other BLE devices in a BLE piconet.

[0161] If the scanning device is in initiator mode, which means that it can receive a broadcasted advertising event and initiate a connection request, the scanning device can initiate a Bluetooth connection with the advertising device by sending a connection request to the advertising device over the advertising physical channel.

[0162] When a scanning device sends a connection request to an advertising device, the scanning device stops initiator mode scanning for further broadcasts and enters connection mode.

[0163] Discovery Procedure

[0164] Devices capable of Bluetooth communication (hereinafter referred to as “Bluetooth devices”) perform advertising and scanning procedures to discover nearby devices or to be discovered by other devices within a given area.

[0165] The discovery process is performed asymmetrically. A Bluetooth device attempting to discover other devices in its vicinity is called a discovering device and listens for devices advertising scannable advertising events. A Bluetooth device discovered and available to other devices is called a discoverable device and actively broadcasts advertising events over the advertising (broadcast) physical channel to make it scannable.

[0166] Both the discovering device and the discoverable device may already be connected to other Bluetooth devices in the piconet.

[0167] Connecting Procedure

[0168] The connection procedure is asymmetric, requiring one Bluetooth device to perform an advertising procedure while another Bluetooth device performs a scanning procedure.

[0169] That is, the advertising process can be targeted, resulting in only one device responding to the advertisement. After receiving an accessible advertising event from the advertising device, a connection can be initiated by sending a connection request to the advertising device via the advertising (broadcast) physical channel.

[0170] Next, we will briefly look at the operating states in BLE technology, namely Advertising State, Scanning State, Initiating State, and Connection State.

[0171] Advertising State

[0172] The Link Layer (LL) enters the advertising state at the direction of the host (stack). When the Link Layer is in the advertising state, it transmits advertising Packet Data Units (PDUs) in advertising events.

[0173] Each advertising event consists of at least one advertising PDU, which are transmitted via the advertising channel indices used. An advertising event may terminate when each advertising PDU has been transmitted via the advertising channel indices used, or may terminate earlier if the advertising device needs to free up space for other functions.

[0174] Scanning State

[0175] The link layer enters the scanning state at the direction of the host (stack). In the scanning state, the link layer listens for advertising channel indices.

[0176] There are two types of scanning states: passive scanning and active scanning, and each scanning type is determined by the host.

[0177] No separate time or advertising channel index is defined for performing scanning.

[0178] During the scanning state, the link layer listens for advertising channel indices for the duration of the scanWindow. The scanInterval is defined as the interval between the start points of two consecutive scan windows.

[0179] The link layer must listen for the completion of all scan intervals in the scan window, as directed by the host, provided there are no scheduling conflicts. In each scan window, the link layer must scan a different advertising channel index. The link layer uses all available advertising channel indices.

[0180] In passive scanning, the link layer only receives packets and does not transmit any packets.

[0181] When actively scanning, the link layer listens to the advertising device for advertising PDUs and depending on the advertising PDU type, may request additional information about the advertising device.

[0182] Initiating State

[0183] The link layer enters the initiated state at the direction of the host (stack).

[0184] When the link layer is in the initiating state, the link layer listens for advertising channel indices.

[0185] During the initiation state, the link layer listens for advertising channel indices during the scan window period.

[0186] connection state

[0187] The link layer enters a connected state when the device performing the connection request, i.e., the initiating device, sends a CONNECT_REQ PDU to the advertising device, or when the advertising device receives a CONNECT_REQ PDU from the initiating device.

[0188] Once a connection enters the connected state, it is considered established. However, the connection need not be considered established at the time it enters the connected state. The only difference between a newly created connection and an established connection is the link-layer connection supervision timeout value.

[0189] When two devices are connected, they act in different roles.

[0190] The link layer that performs the master role is called the master, and the link layer that performs the slave role is called the slave. The master controls the timing of connection events, and connection events indicate the point in time when the master and slave are synchronized.

[0191] Below, we will briefly examine the packets defined in the Bluetooth interface. BLE devices use the packets defined below.

[0192] Packet Format

[0193] The Link Layer has only one packet format, which is used for both advertising channel packets and data channel packets.

[0194] Each packet consists of four fields: Preamble, Access Address, PDU, and CRC.

[0195] When a packet is transmitted on an advertising physical channel, the PDU will be an advertising channel PDU, and when a packet is transmitted on a data physical channel, the PDU will be a data channel PDU.

[0196] Advertising Channel PDU

[0197] Advertising channel PDUs (Packet Data Units) have a 16-bit header and payloads of various sizes.

[0198] The PDU type field of the advertising channel PDU included in the header indicates the PDU type as defined in Table 1 below.

[0199]

[0200] Advertising PDU

[0201] The advertising channel PDU types below are called advertising PDUs and are used in specific events.

[0202] ADV_IND: Connectable non-directional advertising event

[0203] ADV_DIRECT_IND: Connectable directional advertising event

[0204] ADV_NONCONN_IND: Non-directional ad event that is not reachable

[0205] ADV_SCAN_IND: Scannable non-directional ad event

[0206] The above PDUs are transmitted by the link layer in the advertising state and received by the link layer in the scanning state or initiating state.

[0207] Scanning PDU

[0208] The advertising channel PDU type below is called a scanning PDU and is used in the conditions described below.

[0209] SCAN_REQ: Sent by the link layer in scanning state and received by the link layer in advertising state.

[0210] SCAN_RSP: Sent by the link layer in advertising state and received by the link layer in scanning state.

[0211] Initiating PDU

[0212] The advertising channel PDU type below is called an initiation PDU.

[0213] CONNECT_REQ: Sent by the link layer in the initiating state and received by the link layer in the advertising state.

[0214] Data Channel PDU

[0215] A data channel PDU has a 16-bit header, a payload of variable size, and may include a Message Integrity Check (MIC) field.

[0216] The procedures, states, packet formats, etc. in BLE technology discussed above can be applied to perform the methods proposed in this specification.

[0217] Figure 4 shows an example of the structure of the GATT (Generic Attribute Profile) of Bluetooth low energy.

[0218] Referring to Figure 4, a structure for exchanging profile data of Bluetooth low energy can be examined.

[0219] Specifically, GATT (Generic Attribute Profile) defines how to exchange data using services and characteristics between Bluetooth LE devices.

[0220] Typically, a peripheral device (e.g., a sensor device) acts as a GATT server and has definitions for services and characteristics.

[0221] To read or write data, a GATT client sends a data request to a GATT server, and all operations (transactions) are initiated by the GATT client and receive responses from the GATT server.

[0222] The GATT-based operation structure used in Bluetooth LE is based on profiles, services, and characteristics, and can form a vertical structure as shown in Fig. 5.

[0223] The above profile consists of one or more services, and the services may consist of one or more characteristics or other services.

[0224] The above service serves to logically divide data into units and may include one or more characteristics or other services. Each service has a 16-bit or 128-bit identifier called a Universal Unique Identifier (UUID).

[0225] The above characteristic is the lowest unit in the GATT-based operation structure. The characteristic contains only one piece of data and, similar to the above service, has a 16-bit or 128-bit UUID.

[0226] The above characteristics are defined by the values ​​of various pieces of information, and each piece of information requires one attribute. Multiple consecutive attributes can be used for the above characteristics.

[0227] The above attribute consists of four components and has the following meanings:

[0228] - handle: address of the property

[0229] - Type: Type of property

[0230] - Value: The value of the property

[0231] - Permission: Access rights to properties

[0232] FIG. 5 is a flowchart showing an example of a connection procedure method in Bluetooth low energy technology to which the present invention can be applied.

[0233] The server transmits advertising messages to the client through three advertising channels (S5010).

[0234] A server may be called an Advertiser before connection, and a Master after connection. An example of such a server may be a sensor (e.g., a temperature sensor).

[0235] Additionally, a client may be referred to as a "Scanner" before connection and as a "Slave" after connection. An example of a client may be a smartphone.

[0236] As previously discussed, Bluetooth communicates across 40 channels over the 2.4 GHz band. Of these 40 channels, three are advertising channels, used to exchange various advertising packets and other packets used to establish a connection.

[0237] The remaining 37 channels are used for data exchange after connection as data channels.

[0238] After receiving the advertisement message, the client may send a Scan Request message to the server to obtain additional data (e.g., server device name, etc.) from the server.

[0239] In this case, the server transmits a Scan Response message containing additional data in response to a Scan Request message to the client.

[0240] Here, the Scan Request message and the Scan Response message are the end of an advertising packet, and the advertising packet can only contain user data of 31 bytes or less.

[0241] Therefore, if there is data whose size is larger than 3 bytes but the overhead is too high to send the data by establishing a connection, the data is sent in two parts using a scan request message / scan response message.

[0242] Next, the client sends a connection request message to the server to establish a Bluetooth connection with the server (S5020).

[0243] Through this, a Link Layer (LL) connection is established between the server and the client.

[0244] Afterwards, the server and client perform security establishment procedures.

[0245] The secure establishment procedure may be interpreted as or performed incorporating Secure Simple Pairing.

[0246] That is, the security establishment procedure can be carried out through Phase 1 to Phase 3.

[0247] Specifically, a pairing procedure (phase 1) is performed between the server and the client (S5030).

[0248] The pairing procedure involves the client sending a pairing request message to the server, and the server sending a pairing response message to the client.

[0249] The pairing process involves exchanging authentication requirements, input / output capabilities, and key size information between devices. This information is used to determine which key generation method to use in Phase 2.

[0250] Next, as phase 2, legacy pairing or secure connections are performed between the server and the client (S5040).

[0251] In Phase 2, a 128-bit temporary key and a short term key (STK) are generated to perform legacy pairing.

[0252] - Temporary Key: Key created to generate STK

[0253] - Short Term Key (STK): Key value used to create an encrypted connection between devices.

[0254] If a secure connection is performed in Phase 2, a 128-bit Long Term Key (LTK) is generated.

[0255] - Long Term Key (LTK): A key value used not only for encrypted connections between devices but also for future connections.

[0256] Next, as phase 3, a key distribution procedure is performed between the server and the client (S5050).

[0257] This establishes a secure connection between the server and client, forming an encrypted link to enable data transmission and reception.

[0258] Isochronous Channel General

[0259] For audio signals, you can see that audio streaming data or audio data occurs periodically at Idle Event Interval intervals.

[0260] Audio data occurs periodically (or at specific time intervals) depending on its characteristics. Here, a specific time period during which audio data occurs periodically can be expressed as an Idle Event Interval. Each audio data is transmitted during each Idle Event Interval. Furthermore, each audio data can be transmitted throughout the entire Idle Event Interval or a portion of the Idle Event Interval. When transmitting audio streaming data that occurs periodically or regularly using the BLE mechanism, advertising and scanning procedures, communication procedures, and disconnection procedures must be performed each time the generated audio data is transmitted or received. However, audio data is generally generated periodically, and regardless of the amount of data, a latency guarantee for audio data transmission is essential.

[0261] However, there is a problem that latency occurs in audio data transmission when advertising and scanning procedures, communication procedures, and disconnection procedures must be performed every time new audio data is transmitted.

[0262] Audio data transmission through hearing aids (HA) or headsets can achieve higher energy efficiency by utilizing BLE technology rather than Bluetooth BR / EDR technology because the amount of data generated is relatively small. However, as previously discussed, the Data Channel Process of BLE technology requires advertising and connection for each data transmission, which results in a large overhead in data transmission. In particular, the Latency Guarantee, which is absolutely necessary for audio data transmission, cannot be guaranteed.

[0263] In addition, since the Data Channel Process of BLE technology aims to increase energy efficiency by transmitting data that occurs sporadically only when necessary and inducing deep sleep of the BLE device in other time domains, it may be difficult to apply the Data Channel Process of BLE technology to the transmission of audio data that occurs periodically.

[0264] Definition of Isochronous Channels and Related Mechanisms

[0265] A new channel, the Isochronous Channel, is defined to transmit periodically occurring data using BLE technology.

[0266] An isochronous channel is a channel used to transmit isochronous data between devices that use isochronous streams (e.g., Conductor-Member).

[0267] Isochronous data refers to data that is transmitted periodically or regularly at specific time intervals.

[0268] That is, an isochronous channel may refer to a channel through which periodically occurring data, such as audio data or voice data, is transmitted and received in BLE technology. In addition, the isochronous channel may refer to a channel through which data generated based on a user input of a game user's controller device is transmitted and received in a gaming scenario. The isochronous channel may be used to transmit and receive data with a single member, a set of one or more coordinated members, or multiple members. In addition, the isochronous channel corresponds to a flushing channel that may be used to transmit and receive important data in an isochronous stream, such as audio streaming, or in another time domain.

[0269] FIG. 6 illustrates an example of a system structure in which multi-channel audio signals are transmitted between a BLE-based TV transmitting device and multiple BLE audio receiving speakers.

[0270] Figure 6 illustrates an example system architecture that utilizes BLE (Bluetooth Low Energy) technology to wirelessly transmit multi-channel audio signals between a TV transmitter and multiple audio receiver speakers. The system of Figure 6 configures the TV as an audio transmitter (Initiator) and each speaker as an audio receiver (Acceptor), enabling a multi-channel audio environment without wired connections. It utilizes BLE's ISO channel, making it suitable for audio data transmission where time synchronization is critical.

[0271] The TV LE Audio Tx Device includes a video display, an audio decoder / encoder, a controller, and a BLE Tx interface. The audio decoder / encoder converts surround audio formats such as Dolby or DTS into PCM and encodes it into the LC3 codec suitable for BLE transmission. It also supports mono unicast transmission. The TV wirelessly transmits the processed audio signal to external speakers via the BLE Tx interface. Configuration information can be communicated bidirectionally, while the actual audio stream is transmitted unidirectionally.

[0272] The Speaker LE Audio Rx Device consists of a BLE Tx / Rx interface, an audio decoder, an LC3 decoder, a controller, and a speaker driver. Each speaker receives BLE audio data wirelessly transmitted from the TV through the BLE Tx / Rx interface. The received data is restored to the original audio signal through the LC3 decoder and audio decoder, and this signal is output as sound through the speaker driver. Speakers with Tx / Rx interfaces can be used for exchanging setting information with the TV or receiving control signals.

[0273] The system in Figure 6 operates by processing multichannel audio signals, such as 5.1 channels, from a TV and assigning and transmitting them to wireless speakers, either individually or in groups. Each speaker receives and plays audio data for its assigned channel, allowing users to experience a wireless surround sound system without the need for complex audio cable connections. This offers the advantage of increased installation flexibility and a cleaner user experience.

[0274] Figure 7 illustrates an example of a compensation procedure for synchronizing video processing delay and audio processing delay in a Bluetooth low-latency audio system.

[0275] Video and audio signals each have their own unique delays as they pass through various stages of decoding, processing, and output. This delay difference can cause misalignment between video and audio, making it essential to synchronize the two for a natural audiovisual experience.

[0276] The video processing path involves compressed data being decoded, then undergoing image enhancement and display output. This process can include various processes such as frame doubling, anti-aliasing, and TCON (Timing Controller), which, as shown in the diagram, can result in a relatively large delay of approximately 100 ms or more. This is the result of a combination of the physical delay required to display the image on screen and the processing delay.

[0277] The audio processing path, after compressed audio data is decoded, undergoes Bluetooth encoding / transmission / decoding processes, and additional audio enhancement processing may be applied. This includes various audio-related processes such as buffering, pop noise filtering, woofer boost, and active noise cancellation. These processes also introduce delays into the audio signal, and the diagram shows that this audio processing delay is approximately 30 ms or more. As shown in Figure 7, the delay in the audio processing process is relatively short compared to the delay in the image processing process.

[0278] As such, a significant difference arises between video processing delay and audio processing delay. The compensation procedure presented in Figure 7 aims to overcome this delay difference and synchronize video and audio. It utilizes information such as the Presentation Time Stamp (PTS) to determine the original timing information of the video and audio data, and intentionally delays the output of the audio signal with a shorter delay or compensates for this by adjusting the timing so that the video and audio are output nearly simultaneously.

[0279] FIG. 8 illustrates an example of a test stream-based calibration procedure for measuring and adjusting the sound pressure level of each speaker relative to a user's position in a BLE-based audio system.

[0280] Figure 8 illustrates an example of a test stream-based calibration procedure for measuring and adjusting the sound pressure level (SPL) from each speaker relative to the user's listening position (sweet spot) in a Bluetooth low-latency audio system. This process aims to optimize balanced sound from each speaker in a multi-speaker audio system at the user's primary seating position. This procedure utilizes a measurement device, such as a smartphone, to achieve this goal.

[0281] The calibration process begins with playing a test audio stream to each speaker. As shown in the figure, the user's smartphone or control device individually sends a command to play the test stream to each speaker. Each speaker then plays its own corresponding test sound via a unicast connection. This test stream may be a signal with a specific frequency range or characteristics designed for loudness measurement.

[0282] While the test stream plays through each speaker, the user measures the sound pressure level (SPL) arriving at each speaker using a sound pressure measurement device, such as a smartphone, at their primary listening position (the "Sweet Spot"). The figure shows the user sitting in the center, holding the smartphone, and measuring the SPL values ​​coming from each speaker. The measured SPL values ​​for each speaker position may vary depending on factors such as the distance from the speaker, the speaker's performance, and the surrounding environment (e.g., SPL=60, SPL=80, SPL=30).

[0283] Based on the measured sound pressure level of each speaker, the system adjusts the final audio output. By adjusting the volume or gain of each speaker to compensate for differences in measured SPL values, the system ensures that all speakers sound at the intended relative loudness when the user is listening in the "Sweet Spot." This process compensates for volume differences caused by individual speaker locations or characteristics, and optimizes the overall sound field of the multichannel audio system to the user's location, providing a more immersive sound experience.

[0284] FIG. 9 illustrates an example of an inter-speaker synchronization correction structure for correcting sound synchronization errors due to distance differences between front and rear speakers in a multi-channel audio system.

[0285] Fig. 10 illustrates an example of a speaker-to-speaker synchronization structure for compensating for sound synchronization errors due to distance differences between rear speakers in a multi-channel audio system.

[0286] Figures 9 and 10 illustrate various examples of inter-speaker synchronization structures for compensating for acoustic synchronization errors caused by distance differences between multiple speakers and the user's listening position in a multichannel audio system. Since sound propagates through the air at a finite speed, if each speaker is located at a different distance from the listener, the time it takes for the sound to reach the listening position also varies. This difference in sound arrival times can distort the accurate spatial perception and sound image localization of multichannel sound.

[0287] Figure 9 illustrates the effect of the distance difference between the TV speakers (which typically serve as front speakers) and the rear speakers on audio synchronization. Figure 9 shows that the rear speakers are located further away from the listener than the TV speakers (e.g., 3 meters), causing sound from the rear speakers to arrive at the listening position later than sound from the TV speakers. Even though the system transmits audio signals simultaneously, the listener experiences a temporal mismatch due to the physical distance difference.

[0288] Figure 10 illustrates the effect of distance differences between rear speakers on synchronization. The left and right rear speakers may not be positioned exactly the same distance from the listener, and the figure assumes one rear speaker is slightly further away than the other (e.g., a distance difference of 3 meters). Even these slight distance differences between speakers can cause sound arrival times to vary, and especially in sophisticated surround sound environments, these errors can lead to distortion of the sound image.

[0289] To compensate for this audio synchronization error caused by distance differences, the system measures the distance between each speaker and the listening position or calculates the difference in sound arrival times based on a preset value. The system then performs compensation by intentionally delaying the audio signal output from speakers closer to the listening position by the calculated difference. In other words, by adjusting the timing of sound from all speakers to arrive at the listening position, the system ensures that even in multichannel systems with speakers in different locations, users experience a precise and consistent soundstage as designed.

[0290] Figure 11 illustrates an example of an overall system configuration for multi-channel audio transmission between a BLE-based TV and multiple audio receiving devices and a profile structure based on Surround Sound Audio Profile (SSAP).

[0291] Fig. 11 shows an example of the overall system configuration for multi-channel audio transmission between a BLE-based TV and multiple audio receiving devices proposed in the present disclosure and a profile structure based on the Surround Sound Audio Profile (SSAP). The system of Fig. 11 is structured such that a TV, which is a source device, acts as an LE Audio transmitting device (Tx), and multiple speakers act as LE Audio receiving devices (Rx), wirelessly transmitting multi-channel audio via BLE. The figure shows in detail the relationship between each component and profile / service, from the application / host software to the physical layer.

[0292] On the TV transmitter side, the audio signal is processed by the multi-channel audio processor, then converted into a format suitable for BLE transmission through the multi-CH LC3 encoding process. The encoded audio data is transmitted to the LE ISO CH (Isochronous Channel) layer via the I2S interface, where LE Isochronous Channels are configured to broadcast multi-channel audio streams in a synchronized form. Finally, it is wirelessly transmitted to the speakers through the BLE Tx PHY / MAC layer, demonstrating that the data transmission rate can range from 2 Mbps to a maximum of 8 Mbps.

[0293] On the speaker receiving device side, LE ISO CH broadcast data transmitted through BLE Tx / Rx PHY / MAC layers is received. The received data passes through the LE ISO CH layer and is restored to the original multi-channel audio signal through the Multi-CH LC3 audio decoding process. The decoded audio signal is output as sound through the speaker driver. Each speaker receives and plays the audio data of the channel it is responsible for, thereby implementing multi-channel sound. On the speaker side, there are upper layers such as LE Audio Profiles, Sync, and SSAP, which are responsible for interaction and control with the TV.

[0294] In the system of Fig. 11, the Surround Sound Audio Profile (SSAP) and the BLE Audio profiles that form its basis play a crucial role. The Broadcast Audio Profile (BAP) defines the basic functions of audio broadcasting, the Published Audio Capabilities (PAC) provide audio-related capability information including codecs and speaker capabilities, and the Audio Stream Control (ASC) manages audio stream control, QoS, positioning, delay, etc. SSAP can be viewed as a higher-level profile structure that utilizes these sub-profiles to define and control speaker configuration, role assignment, synchronization, etc. required for specific multi-channel audio scenarios such as surround sound.

[0295] Figure 12 illustrates an example of the configuration range and related specifications within a BLE audio system of the Surround Sound Audio Profile (SSAP).

[0296] Figure 12 illustrates the position and configuration scope of the Surround Sound Audio Profile (SSAP) proposed in this disclosure within a BLE audio system, as well as how it relates to the Generic Audio Framework (GAF), codecs, and BLE Core specifications. Figure 12 visually illustrates the role that SSAP plays in the BLE audio technology stack and its relationship with other important components. SSAP is a profile focused on a specific use case: implementing multi-channel surround sound.

[0297] SSAP is presented as one of several "Use Case Profiles" for BLE Audio. It sits on the same level as other use case profiles, such as the Telephony and Media Audio Profile (TMAP) and the Gaming Audio Profile (GMAP), each of which defines how BLE Audio operates for specific application scenarios. SSAP encapsulates and standardizes functions related to creating and controlling surround sound environments, making it easier for developers to implement surround sound features and ensure interoperability between devices.

[0298] Furthermore, SSAP is closely aligned with the GAF specification and codec specifications. GAF provides the basic audio transport and management framework for BLE audio and includes profiles such as the Broadcast Audio Profile (BAP). SSAP leverages these GAF core features to provide additional definitions necessary for implementing surround sound. On the codec side, it specifies that the LC3 codec is used as the default codec for multichannel audio, and SSAP may include specifications for how this LC3 codec is used to configure and process multichannel streams.

[0299] SSAP builds on the BLE core specification, but does not alter the core specification itself. The core specification defines BLE's physical and link-layer capabilities, such as Connected / Broadcast Isochronous Streams (CIS / BIS) and High-precision Data Transfer (HDT), and SSAP operates on this robust foundation. The scope of SSAP's configuration focuses on leveraging these underlying technologies to define elements specific to surround sound system implementation, such as configuring surround sound audio streams, assigning channels to each speaker, synchronization mechanisms, and control and management.

[0300] Figure 13 illustrates an example of multi-channel transmission using Surround Sound Audio Profile (SSAP).

[0301] Referring to FIG. 13, a case may be considered where a TV is the source device. The TV may transmit audio signals to multiple audio receiving devices (e.g., five speakers in FIG. 13) based on SSAP multichannel.

[0302] Figure 14 illustrates another example of multichannel transmission using Surround Sound Audio Profile (SSAP).

[0303] Referring to Fig. 14, a case may be considered where a sound bar connected to a TV (or smartphone) is the source device. The TV and sound bar may be connected via HDMI, BT, etc. The sound bar may transmit audio signals to multiple audio receiving devices (e.g., five speakers in Fig. 14) based on SSAP multichannel.

[0304] FIG. 15 illustrates an example of a channel map update based on the channel status of multiple audio receiving devices in a BLE-based multi-channel audio system.

[0305] Fig. 15 shows an example in which a source device is connected to multiple speakers based on multi-channel. Specifically, the source device is i) connected to a front left speaker (FL in Fig. 15) based on channel 1 (CH 1 in Fig. 15), ii) connected to a front right speaker (FR in Fig. 15) based on channel 2 (CH 2 in Fig. 15), iii) connected to a rear left speaker (RL in Fig. 15) based on channel 3 (CH 3 in Fig. 15), and iv) connected to a rear right speaker (RR in Fig. 15) based on channel 4 (CH 4 in Fig. 15). In this case, i) the source device may be a TV, and ii) the front left speaker and the front right speaker may be TV speakers.

[0306] The source device can transmit audio signals to multiple speakers using Broadcast Isochronous Stream (BIS).

[0307] A source device can receive channel status information for each audio signal from multiple speakers. The channel status information can be transmitted via information related to the channel status. The information related to the channel status can include a Received Signal Strength Indication (RSSI).

[0308] For example, as illustrated in FIG. 15, a case may be considered where the channel status of the rear left speaker is good, while the channel status of the rear right speaker is poor. A source device may receive channel statuses from a plurality of speakers, including the rear left speaker and the rear right speaker. The source device may update a channel map based on the channel statuses of each of the received plurality of speakers. Through this, the source device may reflect the channel statuses of the plurality of speakers and transmit audio signals to a channel with a better status than before.

[0309] Figure 16 illustrates an example of a BLE ISO channel configuration method and a BIS unit multi-channel audio transmission structure based on the Surround Sound Audio Profile (SSAP).

[0310] Figure 16 shows a structure in which multi-channel audio data is transmitted to multiple audio receiving devices based on the isochronous channel (ISO CH) and broadcast isochronous stream (BIS) of BLE.

[0311] For example, a source device may use a single BIS for multi-channel audio or channels for multiple speakers. Specifically, channels for multiple speakers may be assigned within a single BIS, such as Ch1, Ch2, Ch3, and Ch4.

[0312] As another example, a source device may use multiple BISs for multichannel audio or channels of multiple speakers, and each of the channels may be assigned to a respective BIS.

[0313] A source device can transmit audio signals within an ISO interval, which is a periodic time unit. An ISO interval can include multiple sub-intervals. Audio data based on BIS can be structured and transmitted within the sub-intervals.

[0314] Referring to the configuration of BIS1 in FIG. 16, it can be seen that BIS1 contains data for multiple audio channels represented as Ch1, Ch2, Ch3, and Ch4. Each channel may correspond to each of multiple speakers. For example, i) Ch1 may be a channel associated with a front left speaker, ii) Ch2 may be a channel associated with a front right speaker, iii) Ch3 may be a channel associated with a rear left speaker, and iv) Ch4 may be a channel associated with a rear right speaker. Each of the channels may contain audio data for the corresponding speaker. Which channels are included in one BIS may vary depending on the configuration and channel allocation strategy of the system.

[0315] Referring to Ch4 of Fig. 16, it can be seen that the condition of the channel (Ch4) related to the rear right speaker is poor. The rear right speaker may not be able to receive audio data transmitted through Ch4 due to the poor channel condition. In this way, a case in which the condition of a specific channel is poor for an audio signal transmitted through a BIS in a multi-channel audio system may be considered. To solve this problem, the present specification proposes a method of receiving the channel condition of audio signals of multiple speakers while transmitting audio signals through a BIS, and transmitting the audio signal through a better channel based on the channel condition.

[0316] Figure 17 illustrates an example of a channel state transmission / reception and channel map update procedure in multi-channel audio transmission based on one BIS.

[0317] Referring to FIG. 17, the ISO interval may i) include a plurality of sub-intervals corresponding to each channel, and ii) further include a separate spare interval after the plurality of sub-intervals for transmitting audio signals.

[0318] For example, an ISO interval may further include a period for receiving channel status from multiple speakers / sinks after multiple sub-intervals corresponding to each channel.

[0319] For example, if four channels are assigned to four speakers, the ISO interval may include four sub-intervals corresponding to the four channels. Furthermore, the ISO interval may further include a period after the four sub-intervals for receiving the status of the four channels from the four speakers.

[0320] As a more specific example, an ISO interval may include five sub-intervals. Four of the sub-intervals may correspond to each of the four channels, and the remaining one sub-interval may be a section for receiving the status of the four channels from the four speakers.

[0321] The source device can update a channel map based on channel status received from multiple speakers. The channel map can represent a set of channels for broadcasting the audio signal.

[0322] The source device can transmit the audio signal to multiple speakers through better channels than before based on the updated channel map.

[0323] Figure 18 illustrates an example of a channel state transmission / reception and channel map update procedure in multi-channel audio transmission based on multiple BISs.

[0324] Figure 18 shows an example of a configuration in which each audio channel is independently transmitted through a separate BIS. Each of the four BISs in Figure 18 is responsible for one channel and can transmit audio packets in parallel through the channels within the same ISO interval. For example, BIS1 can be responsible for a channel for the front left speaker (Speaker1), BIS2 can be responsible for a channel for the front right speaker (Speaker2), BIS3 can be responsible for a channel for the rear left speaker (Speaker3), and BIS 4 can be responsible for a channel for the rear right speaker (Speaker4). The audio packets of each channel can be sequentially transmitted in parallel within the ISO interval.

[0325] At this time, four BISs (BIS1 to BIS4) can be included in one BIG (Broadcast Isochronous Group).

[0326] When using four channels, an ISO interval can contain a total of five sub-intervals as described above.

[0327] Audio packets for each channel can be transmitted within a single sub-interval. For example, as shown in FIG. 18, a total of four sub-intervals are used for audio packet transmission.

[0328] In addition to the four sub-intervals for audio packet transmission, the remaining sub-intervals may be used to receive channel status from the plurality of speakers. For example, in FIG. 18, it can be confirmed that information related to the channel status of CH#4 for Speaker4 is transmitted in the last sub-interval after the four sub-intervals.

[0329] For example, information related to the channel status may be transmitted based on asynchronous connection-oriented logical transport (ACL).

[0330] Specifically, a source device may be connected to each of a plurality of speakers via an ACL link. Each of the plurality of speakers may transmit channel status-related information (e.g., RSSI) for received audio packets / audio signals to the source device based on the ACL link.

[0331] In other words, the ISO interval may be composed of a total of five sub-intervals, i) four sub-intervals may be associated with four BISs for transmission of audio packets, and ii) the remaining one sub-interval may be associated with an ACL for transmission and reception of information related to channel status.

[0332] The source device can update the channel map based on information related to the received channel status, and transmit audio packets through a good channel based on the updated channel map.

[0333] Figure 19 illustrates an example of a channel state transmission and reception procedure of multiple speakers based on periodic BLE broadcasts and responses.

[0334] A source device can determine the channel status of multiple speakers for an audio signal based on periodic broadcasts and responses (PAwR).

[0335] Referring to Fig. 19, the process of sinks (speaker cells) transmitting responses within a periodic broadcast interval of a source device is illustrated. The periodic broadcast interval may include i) an interval in which a broadcast is transmitted (speaker management module Broadcast Slots) and ii) an interval in which responses to the broadcast are transmitted (Sink (speaker cell) Response Slots). In this case, the periodic interval of the interval in which the broadcast is transmitted and the interval in which the responses are transmitted may be determined / adjusted according to the number of devices and / or device settings. Fig. 19 particularly exemplifies a case in which the interval of the broadcast transmission interval is narrow and the interval of the response transmission interval is wide.

[0336] Source devices can send requests via Broadcast Slots at regular intervals.

[0337] In the above Broadcast Slots section, the source device may transmit a request to multiple speakers to receive channel status information based on a periodic broadcast. In this case, the request may be based on AUX_SYNC_SUBEVENT_IND.

[0338] For example, the broadcast may relate to volume control.

[0339] In the above Response Slots section, multiple speakers may transmit information related to their respective channel states in response to the periodic broadcast. In this case, the response may be based on the AUX_SYNC_SUBEVENT_RSP PDU.

[0340] For example, responses from multiple speakers may be transmitted based on contiguous slots in the time domain.

[0341] As a concrete example, responses from multiple speakers can be transmitted in a single PDU.

[0342] The source device can update its broadcast channel map for audio signal transmission based on the received responses. The source device can transmit the audio signal through the optimal channel based on the updated channel map.

[0343] As another example, a source device may, when necessary, send an ACL link connection request to a specific speaker. The ACL link connection request may be based on AUX_CONNECT_REQ. The specific speaker may transmit channel status-related information to the source device based on the connected ACL link.

[0344] The embodiments described below are specifically described with reference to FIG. 20 in terms of the operation of electronic devices (source devices, TV devices, etc.). The methods described below are distinguished for convenience of explanation, and it is understood that some components of one method may be substituted for some components of another method, or may be applied in combination with each other, as long as they are not mutually exclusive.

[0345] FIG. 20 is a flowchart illustrating a method according to one embodiment of the present specification.

[0346] According to one embodiment of the present specification, a method is provided that is performed by an electronic device such as a TV / source device in a short-range wireless communication system such as Bluetooth.

[0347] The electronic device includes one or more transceivers, one or more processors, and one or more memories.

[0348] The one or more processors may include a first processor corresponding to a host stack; and a second processor corresponding to a first controller stack. The host stack and the controller stack may be connected via a Host Controller Interface (HCI).

[0349] The one or more memories are connected to the one or more processors and can store instructions that perform operations based on being executed by the one or more processors.

[0350] Referring to FIG. 20, a method according to one embodiment of the present specification includes a step of transmitting an audio signal to a plurality of speakers (S2001), a step of receiving information related to a channel state for the audio signal (S2002), a step of determining a channel for transmitting the audio signal based on the information (S2003), and a step of transmitting the audio signal based on the determined channel (S2004).

[0351] At step S2001, the electronic device transmits audio signals to multiple speakers.

[0352] For example, the audio signal may be transmitted to the plurality of speakers in a broadcast manner.

[0353] As a specific example, the audio signal may be transmitted based on a Broadcast Isochronous Stream (BIS).

[0354] For example, the audio signal may include a plurality of sub-audio signals associated with each of the plurality of speakers.

[0355] For example, the individual information may relate to a channel state for a sub-audio signal of each of the plurality of speakers.

[0356] For example, the audio signal may be transmitted according to an ISO interval based on an ISO channel (Isochronous channel).

[0357] For example, the ISO interval may include a plurality of sub-intervals corresponding one-to-one with the plurality of sub-audio signals.

[0358] For example, each of the plurality of sub-audio signals may be transmitted according to a corresponding sub-interval.

[0359] For example, sub-audio signals transmitted through the plurality of sub-intervals for transmitting the audio signal may be transmitted based on BIS.

[0360] As a specific example, the above sub-audio signals can be transmitted based on one BIS.

[0361] As another specific example, the sub audio signals may be transmitted based on multiple BISs.

[0362] As another specific example, each of the sub-audio signals may be transmitted based on a separate BIS. In this case, the BISs associated with the sub-audio signals may be included in a single BIG (Broadcast Isochronous Group).

[0363] In step S2002, the electronic device receives information related to a channel state for the audio signal from a plurality of speakers. At this time, the information includes individual information related to the channel state for the audio signal for each of the plurality of speakers.

[0364] In one embodiment, the ISO interval may further include a section for receiving the information.

[0365] For example, the ISO interval may include i) sub-intervals for transmitting the audio signal and ii) sub-intervals for receiving the information.

[0366] In one embodiment, the information may be received based on asynchronous connection-oriented logical transport (ACL).

[0367] For example, the ACL may be an LE ACL related to low power (Low Energy, LE).

[0368] In one embodiment, the ACL may be related to volume control. In other words, the information / individual information may be received based on the ACL for volume control.

[0369] According to one embodiment, the step (S2002) of receiving the information from the plurality of speakers may include a step of receiving the information based on PAwR (Periodic Advertising with Responses).

[0370] For example, an electronic device may transmit periodic advertising to a plurality of speakers. Subsequently, the electronic device may receive a plurality of responses based on the periodic advertising from the plurality of speakers. The plurality of responses may correspond one-to-one with the plurality of speakers, and each of the plurality of responses may include the individual information of the corresponding speaker.

[0371] For example, the plurality of responses may be received via contiguous slots.

[0372] At step S2003, the electronic device determines a channel for transmitting the audio signal based on the information.

[0373] For example, the electronic device can determine the channel by updating a channel map for transmitting the audio signal based on the information.

[0374] At step S2004, the electronic device transmits the audio signal based on the determined channel.

[0375] For example, the electronic device may transmit the audio signal based on the updated channel map.

[0376] According to another embodiment of the present disclosure, an electronic device is provided. The electronic device includes one or more transceivers, one or more processors, and one or more memories. The memory is configured to store instructions for performing an operating method of the electronic device according to FIG. 20 based on instructions executed by the one or more processors.

[0377] For example, the one or more processors may include a first processor corresponding to a host stack and a second processor corresponding to a first controller stack.

[0378] According to another embodiment of the present disclosure, a control device for controlling an electronic device is provided. The control device includes at least one processor and at least one memory operably connected to the at least one processor. The at least one memory may be configured to store instructions for performing an operating method of the electronic device according to FIG. 20 based on execution by the at least one processor.

[0379] According to various embodiments of the present disclosure, one or more non-transitory computer-readable media (CRM) storing one or more instructions are provided. The one or more instructions, when executed by one or more processors, perform operations, and the operations may include an operating method of an electronic device according to FIG. 20.

[0380] The embodiments described below are specifically described with reference to FIG. 21 in terms of speaker operation. The methods described below are distinguished for convenience of explanation, and it is understood that some components of one method may be substituted for or combined with some components of another method, as long as they are not mutually exclusive.

[0381] FIG. 21 is a flowchart illustrating a method according to another embodiment of the present specification.

[0382] According to another embodiment of the present specification, a method is provided that is performed by a speaker / sink device included in a plurality of speaker / sink devices in a short-range communication system such as Bluetooth.

[0383] The speaker includes one or more transceivers, one or more processors and one or more memories.

[0384] The one or more processors may include a third processor corresponding to a host stack; and a fourth processor corresponding to a third controller stack. The host stack and the controller stack may be connected via a Host Controller Interface (HCI).

[0385] The one or more memories may be connected to the one or more processors and store instructions for performing operations based on being executed by the one or more processors.

[0386] Referring to FIG. 21, a method according to another embodiment of the present specification includes a step of receiving an audio signal (S2101), a step of transmitting individual information related to a channel state for the audio signal (S2102), and a step of receiving an audio signal based on a channel determined based on information related to the channel state for the audio signal of the plurality of speakers (S2103).

[0387] At step S2101, the speaker receives an audio signal from an electronic device.

[0388] For example, the audio signal may be received in a broadcast manner.

[0389] For example, the audio signal may include a plurality of sub-audio signals associated with each of the plurality of speakers.

[0390] For example, the individual information may relate to a channel state for a sub-audio signal of each of the plurality of speakers.

[0391] For example, the audio signal may be received according to an ISO interval based on an ISO channel (Isochronous channel).

[0392] For example, the ISO interval may include a plurality of sub-intervals corresponding one-to-one with the plurality of sub-audio signals.

[0393] For example, each of the plurality of sub-audio signals can be received according to a corresponding sub-interval.

[0394] At step S2102, the speaker transmits individual information related to the channel status for the audio signal to the electronic device.

[0395] In step S2103, the audio signal is received from the electronic device based on a channel determined based on information related to channel states of the audio signals of the plurality of speakers.

[0396] At this time, the information includes individual information related to the channel status for the audio signal of each of the plurality of speakers.

[0397] In one embodiment, the ISO interval may further include a section in which the information is transmitted.

[0398] For example, the information may be transmitted based on asynchronous connection-oriented logical transport (ACL).

[0399] In one embodiment, the ACL may be related to volume control. In other words, the information / individual information may be transmitted based on the ACL for volume control.

[0400] In one embodiment, the step (S2102) of transmitting the individual information to the electronic device may include the step of receiving the periodic advertising from the electronic device and the step of transmitting a response based on the periodic advertising to the electronic device. In this case, the response may include the individual information of the speaker.

[0401] For example, multiple responses corresponding to the multiple speakers one-to-one can be transmitted through contiguous slots.

[0402] According to various embodiments of the present disclosure, a speaker is provided. The speaker includes one or more transceivers, one or more processors, and one or more memories. The one or more memories are configured to store instructions for performing a method of operating the speaker according to FIG. 21 based on instructions executed by the one or more processors.

[0403] The one or more processors may include a third processor corresponding to a host stack and a fourth processor corresponding to a third controller stack.

[0404] According to various embodiments of the present disclosure, a control device for controlling a speaker is provided. The control device includes at least one processor and at least one memory operably connected to the at least one processor. The at least one memory may be configured to store instructions for performing a method for operating a speaker according to FIG. 21 based on instructions executed by the at least one processor.

[0405] According to various embodiments of the present disclosure, one or more non-transitory computer-readable media (CRM) storing one or more commands are provided. The one or more commands, when executed by one or more processors, perform operations, and the operations may include a method of operating a speaker according to FIG. 21.

[0406] The claims described in the various embodiments of the present disclosure may be combined in various ways. For example, the technical features of the method claims of the various embodiments of the present disclosure may be combined and implemented as a device, and the technical features of the device claims of the various embodiments of the present disclosure may be combined and implemented as a method. Furthermore, the technical features of the method claims of the various embodiments of the present disclosure may be combined and implemented as a device, and the technical features of the method claims of the various embodiments of the present disclosure may be combined and implemented as a method.

Claims

1. In a method of operating an electronic device in a short-range wireless communication system, A step of transmitting audio signals to multiple speakers; A step of receiving information related to a channel state for the above audio signal from a plurality of speakers; A step of determining a channel for transmitting the audio signal based on the above information; and A step of transmitting the audio signal based on the determined channel; including: A method, characterized in that the information includes individual information related to the channel status for the audio signal of each of the plurality of speakers.

2. In paragraph 1, A method characterized in that the above audio signal is transmitted to the plurality of speakers in a broadcast manner.

3. In paragraph 1, The above audio signal includes a plurality of sub audio signals associated with each of the plurality of speakers, A method, characterized in that the individual information relates to a channel state for a sub-audio signal of each of the plurality of speakers.

4. In paragraph 3, The above audio signal is transmitted according to the ISO interval based on the ISO channel (Isochronous channel), The above ISO interval includes a plurality of sub-intervals corresponding one-to-one with the plurality of sub-audio signals, A method, characterized in that each of the plurality of sub-audio signals is transmitted according to a corresponding sub-interval.

5. In paragraph 4, A method, characterized in that the ISO interval further includes a section in which the information is received.

6. In paragraph 1, A method characterized in that the above information is received based on asynchronous connection-oriented logical transport (ACL).

7. In paragraph 6, A method, characterized in that the above ACL is related to volume control.

8. In paragraph 1, The step of receiving the above information from the plurality of speakers is: a step of transmitting periodic advertising to the plurality of speakers; and A step of receiving a plurality of responses based on the periodic advertisement from the plurality of speakers; The above multiple responses correspond one-to-one with the above multiple speakers, A method, wherein each of the plurality of responses includes the individual information of the corresponding speaker.

9. In paragraph 8, A method, characterized in that the plurality of responses are received through contiguous slots.

10. In a method for operating a speaker included in a plurality of speakers in a short-range wireless communication system, A step of receiving an audio signal from an electronic device; A step of transmitting individual information related to a channel state for the audio signal to the electronic device; and A step of receiving the audio signal from the electronic device based on a channel determined based on information related to the channel status of the audio signal of the plurality of speakers; including; A method, characterized in that the information includes individual information related to a channel state for the audio signal of each of the plurality of speakers.

11. In paragraph 10, A method characterized in that the above audio signal is received in a broadcast manner.

12. In paragraph 10, The above audio signal includes a plurality of sub audio signals associated with each of the plurality of speakers, A method, characterized in that the individual information relates to a channel state for a sub-audio signal of each of the plurality of speakers.

13. In paragraph 12, The above audio signal is received according to the ISO interval (Isochronous interval) based on the ISO channel (Isochronous channel), The above ISO interval includes a plurality of sub-intervals corresponding one-to-one with the plurality of sub-audio signals, A method, characterized in that each of the plurality of sub-audio signals is received according to a corresponding sub-interval.

14. In paragraph 13, A method, characterized in that the ISO interval further includes a section in which the information is transmitted.

15. In paragraph 10, A method characterized in that the above information is transmitted based on asynchronous connection-oriented logical transport (ACL).

16. In paragraph 15, A method, characterized in that the above ACL is related to volume control.

17. In paragraph 10, The step of transmitting the above individual information to the electronic device is: A step of receiving periodic advertising from the electronic device; and A step of transmitting a response based on the periodic advertisement to the electronic device; A method, characterized in that the response includes the individual information of the speaker.

18. In paragraph 17, A method characterized in that a plurality of responses corresponding one-to-one to the plurality of speakers are transmitted through contiguous slots.

19. In an electronic device in a short-range wireless communication system, One or more transceivers; one or more processors; and One or more memories storing instructions for performing operations based on being executed by one or more processors; The above actions are, A step of transmitting audio signals to multiple speakers; A step of receiving information related to a channel state for the above audio signal from a plurality of speakers; A step of determining a channel for transmitting the audio signal based on the above information; and A step of transmitting the audio signal according to the determined channel; including: A method, characterized in that the information includes individual information related to the channel status for the audio signal of each of the plurality of speakers.

Images