Transmit power control algorithms for sources and sinks in a multi-link session
Transmit power control functionality in wireless audio systems may be implemented by way of a Transmit Power Control (TPC) algorithm devised to control power for both source and sinks in a multi sink session, to reduce power consumption. Information may be passed back and forth between the source and sink devices to adjust power based on the shared information. The TPC algorithm may allow power control on both ends of an RF link, and may have multiple sink devices communicating with a source device. Furthermore, the multiple sink devices and the source device may each be operating at different power levels, and adjust their respective power levels as instructed by the TPC algorithm. Power control is therefore implemented on both ends of the link, where multiple sources and sinks may all operate at different power levels, and all individually adjust their respective power levels.
1. A method for controlling transmit power, the method comprising:
a source device transmitting data to a plurality of sink devices over a wireless Radio Frequency (RF) link;
transmitting, by the plurality of sink devices, acknowledgement messages to the source device over the wireless RF link, wherein the acknowledgement messages are transmitted in response to receiving the data transmitted from the source device;
determining, by the source device, whether acknowledgment messages have been received from each of the plurality of sink devices;
increasing an output transmission power of the source device, if it is determined that acknowledgment messages were not received from all of the plurality of sink devices; and
decreasing an output transmission power of the source device, if it is determined that acknowledgment messages were received from all of the plurality of sink devices.
2. The method of claim 1 , wherein the source device decreasing its output transmission power comprises the source device reducing its output transmission power only if the RSSI for each given sink device indicating that the signal strength of the signals received from the given sink device is greater than a specified minimum value.
3. The method of claim 1 , wherein the source device decreasing an output transmission power comprises the source device reducing an output transmission power only if a current value of the output transmission power is greater than a specified threshold value.
4. The method of claim 1 , further comprising the plurality of sink devices interrupting transmitting second power information to the source device when the source device is not transmitting first power information to the plurality of sink devices.
5. The method of claim 1 , further comprising:
measuring, by the source device, the strength of the signals from the plurality of sink devices used to transmit the acknowledgement messages to the source device; and
wherein the output transmission power of the source device is decreased only if the strength of each of the acknowledgement message signals is above a predefined threshold.
6. The method of claim 1 , further comprising:
transmitting, by the source device, a data packet to each of the plurality of sink devices, wherein the data packet transmitted to a specific sink device specifies whether an acknowledgement message was received from the specific sink device.
7. The method of claim 6 , wherein the data transmitted to an individual sink device of the plurality of sink devices further comprises Received Signal Strength Indicator (RSSI) information indicative of the strength of the signals by which any acknowledgment message are received from the individual sink device.
8. The method of claim 7 , further comprising:
decreasing the output transmission power of each of the plurality of sink devices, if the RSSI signal strength provided by the source device in the data packet is greater than a specified minimum value.
9. A memory medium configured to store programming instructions executable to:
instruct a source device to adjust its output transmission power according to:
transmit data by the source device to a plurality of sink devices over a wireless Radio Frequency (RF) link; and
receive acknowledgement messages, by the source device, from the plurality of sink devices over the wireless RF link, wherein the acknowledgement messages are transmitted in response to receiving the data transmitted from the source device;
determine, by the source device, whether acknowledgment messages have been received from each of the plurality of sink devices;
increase an output transmission power of the source device, if it is determined that acknowledgment messages were not received from all of the plurality of sink devices; and
decrease an output transmission power of the source device, if it is determined that acknowledgment messages were received from all of the plurality of sink device.
10. The memory medium of claim 9 , further configured to store programming instructions executable to:
instruct the source device to reduce its output transmission power only if the RSSI for each respective sink device indicating that the signal strength of the signals received from the respective sink device is greater than a specified minimum value.
11. The memory medium of claim 9 , further configured to store programming instructions executable to:
instruct the source device to reduce an output transmission power only if a current value of the output transmission power is greater than a specified threshold value.
12. The memory medium of claim 9 , further configured to store programming instructions executable to:
transmit, by the source device, a data packet to each of the plurality of sink devices, wherein the data packet transmitted to a specific sink device specifies whether an acknowledgement message was received from the specific sink device.
13. The memory medium of claim 12 , wherein the data further comprise
received Signal Strength Indicator (RSSI) information indicative of the strength of the signals by which acknowledgement messages are received from the source device.
14. A wireless device comprising:
a transmit path comprising a power amplifier (PA) for transmitting signals over a wireless Radio Frequency (RF) link wherein the transmit path is used to transmit data from a source device to a plurality of remote wireless devices;
a receive path configured to receive signals over the wireless RF link; and
a power control block configured to adjust an output power level of the PA;
wherein the wireless device is configured to communicate with the plurality of remote wireless devices over the wireless RF link through the transmit path and the receive path, to transmit data to the plurality of remote wireless devices and to receive a one or more acknowledgement message from the plurality of remote wireless devices;
wherein the acknowledgement messages are transmitted by the plurality of remote devices in response to receiving the data transmitted from the wireless device; and
wherein the power control block is configured to increase the output transmission power level of the wireless device, if it is determined that acknowledgment messages were not received from all of the plurality of remote devices; and
wherein the power control block is further configured to decrease the output transmission power of the source device, if it is determined that acknowledgment messages were received from all of the plurality of remote devices.