Determining latency associated with push-to-talk communications
View Patent ↗A method of determining at least an estimate of media latency for push-to-talk communications includes determining a first time associated with transmitting a first packet from a push-to-talk transceiver device. In a disclosed example, the same device receives a second packet that corresponds to the first packet and includes an indication of the first time, a second time associated with receipt of the first packet by another device such as a push-to-talk server and a third time associated with transmission of the second packet to the push-to-talk transceiver device. That same device determines a fourth time associated with receipt of the second packet. In a disclosed example, the push-to-talk transceiver device uses a relationship between the first time, second time, third time and fourth time for determining at least an estimate of media latency associated with the push-to-talk communication corresponding to the first and second packets. A plurality of latency test procedures are disclosed.
1. A method of determining latency, comprising the steps of:
transmitting a first packet from a push-to-talk (PTT) transceiver device, the first packet including at least an indication of a first time associated with transmitting the first packet;
receiving a second packet at the PTT transceiver device, the second packet corresponding to the first packet and including at least an indication of the first time, a second time associated with another device receiving the first packet and a third time associated with a transmission of the second packet;
determining a fourth time associated with receiving the second packet at the PTT transceiver device; and
determining latency from a relationship between the first, second, third and fourth times.
2. The method of claim 1 , wherein the other device comprises a PTT server and the method comprises
receiving the first packet at the PTT server;
determining the second and third times at the PTT server; and
transmitting the second packet to the PTT transceiver device from the PTT server.
3. The method of claim 2 , comprising
extracting the first time from the first packet; and
determining the second time responsive to the extracting.
4. The method of claim 3 , comprising
ending a PTT call after determining the second time;
ensuring that the PTT transceiver device is one of dormant or active; and
determining the third time after the ensuring.
5. The method of claim 1 , comprising
determining the first time responsive to the PTT transceiver device receiving a floor grant indicating that the PTT transceiver device can transmit the first packet.
6. The method of claim 1 , comprising
allowing the PTT transceiver device to become dormant before transmitting the first packet; and
allowing the PTT transceiver device to become dormant after transmitting the first packet and before receiving the second packet.
7. The method of claim 1 , comprising
allowing the PTT transceiver device to become dormant before transmitting the first packet; and
ensuring that the PTT transceiver device is active before receiving the second packet.
8. The method of claim 1 , comprising
ensuring that the PTT transceiver device is active during the transmitting and receiving steps.
9. The method of claim 1 , comprising
encoding a dual tone multiple frequency digit;
including the encoded dual tone multiple frequency digit as part of the first packet; and
decoding the encoded dual tone multiple frequency digit from the received second packet.
10. The method of claim 9 , comprising
determining the fourth time responsive to the decoding.
11. The method of claim 1 , comprising
including padding as part of the first packet, the padding having a size such that the first packet has a size corresponding to a packet used for an audible PTT communication.
12. The method of claim 1 , wherein the relationship comprises a total of a difference between the second time and the first time plus a difference between the fourth time and the third time plus a dejitter time associated with at least a dejitter buffer of the PTT transceiver device.
13. The method of claim 1 , wherein the relationship comprises a total of a difference between the second time and the first time plus a difference between the fourth time and the third time plus a dejitter time associated with at least a dejitter buffer of the PTT transceiver device plus an audio encoding time plus an audio decoding time.