Bluetooth audio communication system and method for acknowledging reception of packets of audio streams at a slave and master devices

A method applied to a wireless Bluetooth audio communication system includes: providing an audio gateway of a first piconet to communicate with a master device in the first piconet and to transmit at least one packet of audio stream to the master device and a slave device; employing a first transceiver as the master device to receive the at least one packet of the audio stream from the audio gateway; and, employing a second transceiver as the slave device to receive the at least one packet of the audio stream from the audio gateway and to acknowledge the first transceiver whether the second transceiver has successfully received the at least one packet of the audio stream from the audio gateway.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a wireless audio communication mechanism, and more particularly to a wireless Bluetooth audio communication system, corresponding transceivers, and a corresponding method.

2. Description of the Prior Art

Generally speaking, in a conventional Bluetooth audio communication system, for example, two transceivers running Bluetooth communication protocol may be used as headsets or headphones for a user wherein one transceiver is used as a master device and the other transceiver is used as a slave device. The master device of conventional Bluetooth audio communication system is arranged to relay packets of audio stream transmitted from an audio gateway of such system to the slave device so that the two transceivers can play the audio stream for the user. Due to this, the master device of conventional Bluetooth audio communication system necessarily consumes more power than the slave device. In addition, unfortunately the timings that the master device and slave device receive the same audio packet may be different, and thus the master device and slave device may play the audio stream asynchronously. The audio quality heard by the user will be worse.

SUMMARY OF THE INVENTION

Therefore one of the objectives of the invention is to provide a wireless Bluetooth audio communication system, corresponding transceivers, and a corresponding method, to solve the above-mentioned problems.

According to embodiments of the invention, a wireless Bluetooth audio communication system is disclosed. The wireless Bluetooth audio communication system comprises an audio gateway of a first piconet, a first transceiver, and a second transceiver. The audio gateway of the first piconet is configured to communicate with a master device in the first piconet and to transmit at least one packet of audio stream to the master device and a slave device. The first transceiver is used as the master device, and is configured to receive the at least one packet of the audio stream. The second transceiver is used as the slave device, and is configured to receive the at least one packet of the audio stream transmitted from the audio gateway and configured to acknowledge the first transceiver whether the second transceiver has successfully received the at least one packet of the audio stream.

According to the embodiments, a transceiver of a wireless Bluetooth audio communication system in which an audio gateway of a first piconet is arranged to communicate with a master device in the first piconet and to transmit at least one packet of audio stream to the master device and a slave device is disclosed. The transceiver is used as the master device and comprises a communication circuit and a processing circuit. The communication circuit is configured to receive the at least one packet of the audio stream from the audio gateway. The processing circuit is coupled to the communication circuit and is configured to control the communication circuit to acknowledge the audio gateway whether the transceiver has successfully received the at least one packet of the audio stream and the slave device has successfully received the at least one packet of the audio stream from the audio gateway.

According to the embodiments, a transceiver of a wireless Bluetooth audio communication system in which an audio gateway of a first piconet is arranged to communicate with a master device in the first piconet and to transmit at least one packet of audio stream to the master device and a slave device is disclosed. The transceiver is used as the slave device and comprises a communication circuit and a processing circuit. The communication circuit is configured to receive the at least one packet of the audio stream from the audio gateway. The processing circuit is coupled to the communication circuit and is configured to control the communication circuit to acknowledge the master device whether the second transceiver has successfully received the at least one packet of the audio stream from the audio gateway.

According to the embodiments, a method applied to a wireless Bluetooth audio communication system is disclosed. The method comprises: providing an audio gateway of a first piconet to communicate with a master device in the first piconet and to transmit at least one packet of audio stream to the master device and a slave device; employing a first transceiver as the master device to receive the at least one packet of the audio stream from the audio gateway; and, employing a second transceiver as the slave device to receive the at least one packet of the audio stream from the audio gateway and to acknowledge the first transceiver whether the second transceiver has successfully received the at least one packet of the audio stream from the audio gateway.

According to the embodiments, a method applied to a transceiver of a wireless Bluetooth audio communication system in which an audio gateway of a first piconet is arranged to communicate with a master device in the first piconet and to transmit at least one packet of audio stream to the master device and a slave device is disclosed. The transceiver is used as the master device. The method comprises: receiving the at least one packet of the audio stream; and acknowledging to the audio gateway whether the transceiver has successfully received the at least one packet of the audio stream and the at least one packet of the audio stream is received by the slave device.

According to the embodiments, a method applied to a transceiver of a wireless Bluetooth audio communication system in which an audio gateway of a first piconet is arranged to communicate with a master device in the first piconet and to transmit at least one packet of audio stream to the master device and a slave device is disclosed. The transceiver is used as the slave device. The method comprises: receiving the at least one packet of the audio stream; and acknowledging to the master device whether the transceiver has successfully received the at least one packet of the audio stream transmitted from the audio gateway.

DETAILED DESCRIPTION

The invention is to provide a novel wireless communication system running Bluetooth compliant audio communication protocol, to provide Bluetooth compliant traffic control to maximize radio spectrum usage efficiency in true wireless stereo application. In the system, a transceiver used as a slave device is to sniff/monitor/receive packet(s) such as packet(s) of audio stream wirelessly transmitted from a gateway such as audio gateway and to acknowledge a different transceiver used as a master device whether the slave device successfully receives the packet(s) of audio stream. The master device is arranged to acknowledge the gateway whether the packet(s) is/are successfully received by both of the master device and slave device. Compared to the conventional Bluetooth audio transmission scheme, it is not necessary for the master device to relay packets of the gateway to the slave device, and the power consumption of master device and slave device can be balanced. In addition, the timings of packet reception of master device and slave device can be synchronized in the same time slots. Thus, if the transceivers of the invention are used as headphones for a user, the audio quality can be improved significantly compared to the conventional Bluetooth audio transmission scheme.

Refer toFIG. 1.FIG. 1is a block diagram of a wireless Bluetooth audio communication system100according to embodiments of the invention. As shown inFIG. 1, the communication system100comprises an audio gateway105of a first piconet PN1, a first transceiver110A, and a second transceiver110B. The audio gateway105for example is a mobile phone device or smart phone device (but not limited). The transceivers110A and110B are for example headsets, headphones, or wireless speakers (but not limited) which can receive wireless packet(s) of audio stream. In practice, the first transceiver110A comprises a communication circuit1101A and a processing circuit1102B, and the second transceiver110B comprises a communication circuit1101B and a processing circuit1102B. The communication circuits1101A and1101B are arranged to receive packet(s) of audio stream, respectively, and can be arrange to communicate with each other. The processing circuits1102A and1102B are used for controlling the communication circuits1101A and1101B, respectively.

A piconet for example is defined as an ad hoc network that links a wireless user group of devices using Bluetooth technology protocols. The audio gateway105and a master device can communicate with each other directly in the first piconet PN1, and a slave device does not communicate with audio gateway105directly in the first piconet PN1. For example, the master device can send an acknowledgement signal back to the audio gateway105to notify the audio gateway105of successfully receiving a packet of audio stream from audio gateway105. A slave device does not notify the audio gateway105by directly sending an acknowledgement signal to audio gateway105.

In the embodiments, the audio gateway105is arranged to communicate with the master device in the first piconet PN1and to transmit packet(s) of audio stream to the master device and the slave device. For instance, the first transceiver110A is used as the above-mentioned master device, and the communication circuit1101A is configured to receive the packet(s) of audio stream.

In a first embodiment, the processing circuit1102A is arranged control the communication circuit1101A to send a first acknowledgement signal ACK1to the audio gateway105when determines that the communication circuit1101A has successfully received an packet of audio stream and also has successfully received a second acknowledgement signal ACK2sent from the slave device. The second transceiver110B is used as the above-mentioned slave device, and its communication circuit1101B is configured to receive the packet of audio stream. The processing circuit1102B of slave device110B can control the communication circuit1101B to send the second acknowledgement signal ACK2to the master device110A when determining that the communication circuit1102B of slave device110B has successfully received such packet of audio stream sent from the audio gateway105. That is, only when the master device110A has successfully received the packet of audio stream and also has successfully received the second acknowledgement signal ACK2of the slave device110B, the master device110A is arranged to send the first acknowledgement signal ACK1to the audio gateway105. The slave device110B is not configured to directly acknowledge to the audio gateway105, and is arranged to directly communicate with the master device110A.

In practice, the master device110A is arranged to send the acknowledgement signal ACK1to the audio gateway105until receiving the acknowledgement signal ACK2of the packet of audio stream, sent from the slave device110B, and also receiving the same packet of audio stream. Each audio packet to be transmitted for example has a sequence number which corresponds to a sequence number of an acknowledgement signal. In one embodiment, the value of sequence number may range from 1 to N (a positive integer). For transmission of each audio packet, when the audio gateway105wirelessly transmits an audio packet having a particular sequence value to the air, the slave device110B can send the acknowledgement signal ACK2having the same sequence value to the master device110A if the slave device110B sniffs and successfully receives the audio packet. When the master device110A receives the same audio packet and the acknowledgement signal ACK2having the same sequence value, the master device110A sends the acknowledgement signal ACK1having the same sequence value to the audio gateway105. Once receiving the acknowledgement signal ACK1having the same sequence value, the audio gateway105can determine that such audio packet has been received by the devices110A and110B and is not lost.

In addition, the audio gateway105may trigger an expiration timer for transmission of each audio packet, and count down the expiration timer before receiving the acknowledgement signal ACK1having a sequence value which is equal to the sequence value of an audio packet that has been transmitted. The audio gateway105determines that such transmitted audio packet is lost and then repeats the transmission of such lost audio packet if the expiration timer is expired. By doing so, packets of audio stream receptions of the devices110A and110B can be synchronized in the same time slots. The audio quality heard by users can be improved significantly.

Additionally, in a second embodiment, the acknowledgement signals may indicate negative acknowledgements. For instance, for transmission of each audio packet, when the audio gateway105wirelessly transmits an audio packet having a particular sequence value to the air, the slave device110B can send a negative acknowledgement signal NACK2having the same sequence value to the master device110A if the slave device110B fails to successfully receive the packet of audio stream (the slave device110may not correctly receive the packet or the packet is lost). When the master device110A also fails to receive the same packet of audio stream and/or receives the negative acknowledgement signal NACK2having the same sequence value, the master device110A sends a negative acknowledgement signal NACK1having the same sequence value to the audio gateway105. Once receiving the negative acknowledgement signal NACK1having the same sequence value, the audio gateway105can determine that such audio packet is not successfully received by the devices110A and110B and then repeats the transmission of such audio packet. By doing so, audio packet receptions of the devices110A and110B can be synchronized in the same time slots. The audio quality heard by users can be improved.

Additionally, in a third embodiment, the processing circuit1102A of master device110A can be arranged to control communication circuit1101A to transmit a negotiation configuration packet to the slave device110B to form a second piconet PN2which is different from the first piconet PN1in which the master device110A communicates with the audio gateway105. In addition, the processing circuit1102B of slave device110B is arranged to control communication circuit1101B to send a corresponding acknowledgement packet to the master device110A if the negotiation configuration packet has been successfully accepted by the slave device110B. That is, the master device110A can be arranged to communicate with the slave device110B directly in another different piconet. If the master device110A is transmitting the negotiation configuration packet to the slave device110B to negotiate with the slave device110B currently, a packet of audio stream currently transmitted by the audio gateway105is to be discarded by the master device110A.

Further, based on the negotiation configuration packet and corresponding acknowledgement packet, the first transceiver110A and second transceiver110B, respectively used as master device and slave device, can be arranged to re-determine which one is the master device after the negotiation between first transceiver110A and second transceiver110B has established. For example, the first transceiver110A, originally used as the master device, can be re-determined as the slave device, and the second transceiver110B, originally used as the slave device, can be re-determined as the master device. That is, the roles of transceivers110A and110B can be exchanged based on the negotiation mentioned above.

Further, after the second piconet PN2is established, no matter which one is used as the master device, the transceivers110A and110B can be arranged to exchange and/or share control information and data.

Refer toFIG. 2.FIG. 2is an example diagram showing traffics of audio gateway105, master device110A, and slave device110B over aligned time slot boundary. Piconets PN1and PN2have aligned Bluetooth time slot boundary. As shown inFIG. 2, in a first scenario, at time slot S1, the audio gateway105may wirelessly transmit a packet of audio stream to the air, and both the master device110A and slave device110B successfully receives such packet of audio stream at time slot S1. The slave device110B at slot S1is arranged to send the second acknowledge ACK2to the slave device110B. The master device110A is arranged to send the first acknowledgement signal ACK1to the audio gateway105at time slot S2after successfully receiving the packet of audio stream and also receiving the second acknowledge ACK2from the slave device110B. Thus, the audio gateway105can determine that the packet of audio stream has been received by both the devices and is arranged to not re-transmit the packet.

In a second scenario, at time slot S3, the audio gateway105may wirelessly transmit a packet of audio stream to the air, and the slave device110B successfully receives such packet of audio stream at time slot S3while the master device110A fails to receive such packet of audio stream (this packet is lost for device110A) at time slot S3. The slave device110B is arranged to send the second acknowledge ACK2to the slave device110B at time slot S3after receiving the packet. The master device110A is arranged to send the negative acknowledgement signal NACK1to the audio gateway105at time slot S4since the packet is not received by the device110A. Thus, the audio gateway105can determine to re-transmit the packet when receiving the negative acknowledgement signal NACK1.

In a third scenario, at time slot S5, the audio gateway105may wirelessly transmit a packet of audio stream to the air, and the master device110A successfully receives such packet of audio stream at time slot S5while the slave device110B fails to receive such packet of audio stream (this packet is lost for device110B) at time slot S5. In this example, the slave device110B is arranged to not send an acknowledgement signal to the master device110A since the packet is not received. In another example, the slave device110B may be arranged to send the negative acknowledgement signal NACK2to the master device110A if the packet is not received. This is not meant to be a limitation. The master device110A may be arranged to send the negative acknowledgement signal NACK1to the audio gateway105at time slot S6since the master device110A fails to receive any acknowledgement signal from the slave device110B (The master device110A can determine that the packet is lost for the device110B). Thus, the audio gateway105can determine to re-transmit the packet when receiving the negative acknowledgement signal NACK1.

In a fourth scenario, at time slot S7, the audio gateway105may wirelessly transmit a packet of audio stream to the air, and both the master device110A and slave device110B successfully receives such packet of audio stream at time slot S7. The slave device110B at time slot S7is arranged to send the second acknowledge ACK2to the slave device110B. The master device110A is arranged to send the first acknowledgement signal ACK1to the audio gateway105at time slot S8after successfully receiving the packet of audio stream and also receiving the second acknowledge ACK2from the slave device110B. Thus, the audio gateway105can determine that the packet of audio stream has been received by both the devices and is arranged to not re-transmit the packet.

In a fifth scenario, at time slot S9, the audio gateway105may wirelessly transmit a packet of audio stream to the air, and both the master device110A and slave device110B successfully receives such packet of audio stream at time slot S9. The slave device110B is arranged to send the second acknowledge ACK2to the master device110A at time slot S9. The master device110A is arranged to send the first acknowledgement signal ACK1to the audio gateway105at time slot S10after successfully receiving the packet of audio stream and also receiving the second acknowledge ACK2from the slave device110B. Thus, the audio gateway105can determine that the packet of audio stream has been received by both the devices and is arranged to not re-transmit the packet. In addition, after sending the first acknowledgement signal ACK1, at time slot S10, the master device110A may be arranged to communicate with the slave device110B by sending a negotiation configuration packet NP to the slave device110B directly. For example, the master device110A may notify the slave device110B of transmitting data and/or control information to the slave device110B by sending the negotiation configuration packet NP. This negotiation configuration packet NP makes the master device110A and slave device110B form a second piconet PN2. Then, at time slot S11, the master device110A is arranged to transmit a data packet and/or a control packet to the slave device110B. At time slot S12, the slave device110B in the second piconet PN2successfully receives the data packet and/or control packet from master device110A and then transmits a corresponding acknowledgement packet ACK2′ to the master device110A.

At time slot S13, when the master device110A uses the second piconet PN2to transmit other data packet and/or control packet to the slave device110B, a different packet of audio stream transmitted from the audio gateway105using the piconet PN1is to be discarded by the master device110A. In addition, a packet of audio stream transmitted from the audio gateway105using the piconet PN1will also be discarded by master device110A if the master device110A is transmitting the negotiation configuration packet NP to the slave device110B to negotiate with the slave device110B. The slave device110B in the second piconet PN2successfully receives the data packet and/or control packet from master device110A and then at time slot S14transmits the corresponding acknowledgement packet ACK2′ to the master device110A using the second piconet PN2.

In a sixth scenario, the master device110A and slave device110B may end the data and control information transmission using the second piconet PN2, and then the traffic transmission is initiated by the audio gateway105at time slot S15. At time slot S15, the audio gateway105wirelessly transmits a packet of audio stream to the air, and both the master device110A and slave device110B successfully receives such packet of audio stream at time slot S15. The slave device110B is arranged to send the second acknowledge ACK2to the master device110A at time slot S15. The master device110A is arranged to send the first acknowledgement signal ACK1to the audio gateway105at time slot S16after successfully receiving the packet of audio stream and also receiving the second acknowledge ACK2from the slave device110B. Thus, the audio gateway105can determine that the packet of audio stream has been received by both the devices and is arranged to not re-transmit the packet. In addition, after sending the first acknowledgement signal ACK1, at time slot S16, the master device110A may communicate with the slave device110B by sending the negotiation configuration packet NP to the slave device110B directly. For example, the master device110A may send the negotiation configuration packet NP to slave device110B to negotiate with slave device110B which device is re-determined as a new master device. For example, the master device110A may use the negotiation configuration packet NP to indicate that the slave device110B is re-determined as a new master device. If the device110B accepts or agrees this configuration, the device110B can send transmits a corresponding acknowledgement signal to the device110A, and the configuration is completed.