Scheduling transmission of traffic treated less preferentially despite timing requirements

1. A method in a first device having a first communication interface compatible with a first communication protocol for communications over a wireless medium and a second communication interface compatible with a second communication protocol for communications over the wireless medium, the method comprising:

establishing a communication session over the wireless medium with an external device compatible with the first communication protocol;

determining a maximum capacity of a buffer at the external device for receipt of audio samples to be transmitted in packets from the first device to the external device in an asynchronous connectionless link over the wireless medium;

determining a playout rate at the external device of the audio samples from the buffer;

determining that a future event at the first device will preempt or supplant transmission of the audio samples from the first device to the external device;

determining a forecasted deficit in audio samples for playout at the buffer due to the future event; and

scheduling access by the first communication interface to the wireless medium in advance of the future event for transmission of audio samples in packets from the first device to the external device to reduce the forecasted deficit.

2. The method as recited in claim 1 , wherein the future event at the first device involves the second communication interface.

3. The method as recited in claim 1 , wherein the future event at the first device involves high priority traffic at the first communication interface.

4. The method as recited in claim 1 , wherein the second communication protocol comprises a wireless local area network protocol.

5. The method as recited in claim 1 , wherein the first communication protocol comprises an adaptive frequency hopping spread spectrum wireless personal area network protocol.

6. The method as recited in claim 5 , wherein determining the maximum capacity of the buffer comprises:

transmitting, via the first communication interface to the external device, a request for an indication of the maximum capacity of the buffer; and

in response to transmitting the request, receiving from the external device via the first communication interface the indication of the maximum capacity of the buffer.

7. The method as recited in claim 6 , wherein transmitting the request comprises transmitting an Audio Video Distribution Transport Protocol (AVDTP) Get_Capabilities command signal including a buffer_size field and receiving the indication comprises receiving a buffer_size_response message indicating the maximum capacity of the buffer.

8. The method as recited in claim 1 , wherein determining the maximum capacity of the buffer comprises:

transmitting, via the first communication interface to the external device, a request for an indication of the maximum capacity of the buffer; and

in response to transmitting the request, receiving from the external device via the first communication interface the indication of the maximum capacity of the buffer.

9. The method as recited in claim 1 , wherein determining the maximum capacity of the buffer comprises:

transmitting audio samples in packets from the first device to the external device in the asynchronous connectionless link over the wireless medium until the external device signals to the first device that the buffer is full;

calculating an average time to transmit a single audio sample from the first device to the external device;

calculating an average time to playback a single audio sample at the external device; and

calculating an estimated maximum capacity of the buffer from the average time to transmit and the average time to playback.

10. A first device comprising:

a first communication interface, the first communication interface compatible with a first communication protocol for communications over a wireless medium;

a second communication interface, the second communication interface compatible with a second communication protocol for communications over the wireless medium;

an audio coder coupled to the first communication interface; and

a scheduler coupled to the first communication interface,

wherein the first device is operable to establish via the first communication interface a communication session over the wireless medium with an external device compatible with the first communication protocol,

wherein the first device is operable to determine a maximum capacity of a buffer at the external device for receipt of audio samples to be transmitted in packets from the first device to the external device in an asynchronous connectionless link over the wireless medium,

wherein the scheduler is to take the maximum capacity of the buffer into account in scheduling access by the first communication interface to the wireless medium for transmission of the audio samples, and

wherein the first device is operable to determine the maximum capacity of the buffer by:

transmitting audio samples in packets from the first device to the external device in the asynchronous connectionless link over the wireless medium until the external device signals to the first device that the buffer is full;

calculating an average time to transmit a single audio sample from the first device to the external device;

calculating an average time to playback a single audio sample at the external device; and

calculating an estimated maximum capacity of the buffer from the average time to transmit and the average time to playback.

11. A first device comprising:

a first communication interface, the first communication interface compatible with a first communication protocol for communications over a wireless medium;

a second communication interface, the second communication interface compatible with a second communication protocol for communications over the wireless medium;

an audio coder coupled to the first communication interface; and

a scheduler coupled to the first communication interface,

wherein the first device is operable:

to establish via the first communication interface a communication session over the wireless medium with an external device compatible with the first communication protocol;

to determine a maximum capacity of a buffer at the external device for receipt of audio samples to be transmitted in packets from the first device to the external device in an asynchronous connectionless link over the wireless medium;

to determine a playout rate at the external device of the audio samples from the buffer;

to determine that a future event at the first device will preempt or supplant transmission of the audio samples from the first device to the external device;

to determine a forecasted deficit in audio samples for playout at the buffer due to the future event; and

to schedule access by the first communication interface to the wireless medium in advance of the future event for transmission of audio samples in packets from the first device to the external device to reduce the forecasted deficit.

12. The first device as recited in claim 11 , wherein the future event at the first device involves the second communication interface.

13. The first device as recited in claim 11 , wherein the future event at the first device involves high priority traffic at the first communication interface.

14. The first device as recited in claim 11 , wherein the second communication protocol comprises a wireless local area network protocol.

15. The first device as recited in claim 11 , wherein the first communication protocol comprises an adaptive frequency hopping spread spectrum wireless personal area network protocol.

16. The first device as recited in claim 15 , wherein the first device is operable to determine the maximum capacity of the buffer by:

transmitting, via the first communication interface to the external device, a request for an indication of the maximum capacity of the buffer; and

in response to transmitting the request, receiving from the external device via the first communication interface the indication of the maximum capacity of the buffer.

17. The first device as recited in claim 16 , wherein the first communication protocol comprises an adaptive frequency hopping spread spectrum wireless personal area network protocol and wherein transmitting the request comprises transmitting an Audio Video Distribution Transport Protocol (AVDTP) Get_Capabilities command signal including a buffer_size field and receiving the indication comprises receiving a buffer_size_response message indicating the maximum capacity of the buffer.

18. The first device as recited in claim 11 , wherein the first device is operable to determine the maximum capacity of the buffer by:

transmitting, via the first communication interface to the external device, a request for an indication of the maximum capacity of the buffer; and

in response to transmitting the request, receiving from the external device via the first communication interface the indication of the maximum capacity of the buffer.

19. The first device as recited in claim 11 , wherein the first device is operable to determine the maximum capacity of the buffer by:

transmitting audio samples in packets from the first device to the external device in the asynchronous connectionless link over the wireless medium until the external device signals to the first device that the buffer is full;

calculating an average time to transmit a single audio sample from the first device to the external device;

calculating an average time to playback a single audio sample at the external device; and

calculating an estimated maximum capacity of the buffer from the average time to transmit and the average time to playback.