Automatic retransmission in communications systems
View Patent ↗Automatic retransmission in communications systems. In one embodiment, a portion of data is identified to be retransmitted based on feedback information indicating a negative acknowledgement (NACK) during a cyclic redundancy check (CRC) on a previous transmission of the portion of data. A retransmission mode is selected for the portion of data, from at least a first mode that retransmits the portion of data on at least a first transmitter antenna while transmitting new data on at least a second transmitter antenna, based on first desired transmission characteristics; and a second mode that retransmits the portion of data simultaneously on at least the first and second transmitter antennas, based on second desired transmission characteristics.
1. A communications device, comprising:
one or more processors;
a transmitter having a plurality of transmitter antennas; and
one or more computer-readable media having stored thereon computer-executable instructions that are executable by the one or more processors, including computer-executable instructions that configure the communications device to perform at least the following:
obtain cyclic redundancy check (CRC) information on a portion of data, the portion of data having been previously transmitted at a first transmitter antenna of the plurality of transmitter antennas; and
when the CRC information indicates a negative acknowledgment (NACK) for the portion of data, select a retransmission mode for the portion of data, from among at least:
a first mode that retransmits the portion of data on at least a second transmitter antenna of the plurality of transmitter antennas, while transmitting new data on at least the first transmitter antenna, the first mode being selected based on a particular level of delay being permissible; and
a second mode that retransmits the portion of data on at least the first transmitter antenna, while transmitting the new data on at least the second transmitter antenna, the second mode being selected based on reducing delay below the particular level of delay.
2. The communications device of claim 1 , wherein the first mode retransmits data only on transmitter antennas that transmitted data that received an acknowledgement (ACK) during a previous transmission.
3. The communications device of claim 1 , wherein the first mode transmits new data only on transmitter antennas that transmitted data that received a NACK during a previous transmission.
4. The communications device of claim 1 , wherein the second mode retransmits data only on transmitter antennas that transmitted data that received a NACK during a previous transmission.
5. The communications device of claim 1 , wherein the second mode transmits new data only on transmitter antennas that transmitted data that received an acknowledgement (ACK) during a previous transmission.
6. The communications device of claim 1 , also including computer-executable instructions that configure the communications device to store long-term retransmission statistics for each transmitter antenna.
7. The communications device of claim 1 , further comprising:
a receiver having a plurality of receiver antennas.
8. The communications device of claim 7 , wherein a CRC is executed for data received at each receiver antenna.
9. The communications device of claim 1 , also including computer-executable instructions that also configure the communications device to select the retransmission mode for the portion of data from among a third mode that retransmits the portion of data on a transmitter antenna of the plurality of transmitter antennas that transmitted data that received an acknowledgement (ACK) during a previous transmission, without transmitting any data on the first transmitter antenna during the retransmission of the portion of data, the third mode being selected based on a particular error rate being permissible.
10. The communications device of claim 9 , also including computer-executable instructions that also configure the communications device to select the retransmission mode for the portion of data from among a fourth mode that simultaneously retransmits the portion of data on each of the plurality of transmitter antennas, the fourth mode being selected based on reducing errors below the particular error rate.
11. A communications device, comprising:
one or more processors;
a transmitter having a plurality of transmitter antennas; and
one or more computer-readable media having stored thereon computer-executable instructions that are executable by the one or more processors, including computer-executable instructions that configure the communications device to perform at least the following:
obtain cyclic redundancy check (CRC) information on a portion of data, the portion of data having been previously transmitted at a first transmitter antenna of the plurality of transmitter antennas; and
when the CRC information indicates a negative acknowledgment (NACK) for the portion of data, select a retransmission mode for the portion of data, from among at least:
a first mode that retransmits the portion of data on at least a second transmitter antenna of the plurality of transmitter antennas that transmitted data that received an acknowledgement (ACK) during a previous transmission, without transmitting any data on the first transmitter antenna during the retransmission of the portion of data on the second transmitter antenna, the first mode being selected based on a particular error rate being permissible; and
a second mode that simultaneously retransmits the portion of data on at least the first transmitter antenna and the second transmitter antenna, the second mode being selected based on reducing errors below the particular error rate.
12. The communications device of claim 11 , wherein the portion of data is retransmitted using space-time block coding (STBC).
13. The communications device of claim 11 , wherein the first mode retransmits the portion of data on all transmitter antennas of the plurality of transmitter antennas that transmitted data that received an acknowledgement (ACK) during a previous transmission.
14. The communications device of claim 11 , wherein the first mode refrains from transmitting data on any transmitter antenna of the plurality of transmitter antennas that transmitted data that received a NACK during a previous transmission during the retransmission of the portion of data on the second transmitter antenna.
15. The communications device of claim 11 , wherein the second mode simultaneously retransmits the portion of data on each of the plurality of transmitter antennas.
16. The communications device of claim 11 , further comprising:
a receiver having a plurality of receiver antennas.
17. The communications device of claim 16 , wherein a CRC is executed for data received at each receiver antenna.
18. The communications device of claim 11 , also including computer-executable instructions that also configure the communications device to select the retransmission mode for the portion of data from among a third mode that retransmits the portion of data on at least the second transmitter antenna, while transmitting new data on at least the first transmitter antenna, the third mode being selected based on a particular level of delay being permissible.
19. The communications device of claim 18 , also including computer-executable instructions that also configure the communications device to select the retransmission mode for the portion of data from among a fourth mode that retransmits the portion of data on at least the first transmitter antenna, while transmitting the new data on at least the second transmitter antenna, the fourth mode being selected based on reducing delay below the particular level of delay.
20. A communications device, comprising:
one or more processors;
a transmitter having a plurality of transmitter antennas; and
one or more computer-readable media having stored thereon computer-executable instructions that are executable by the one or more processors, including computer-executable instructions that configure the communications device to perform at least the following:
obtain cyclic redundancy check (CRC) information on a portion of data, the portion of data having been previously transmitted at a first transmitter antenna of the plurality of transmitter antennas; and
when the CRC information indicates a negative acknowledgment (NACK) for the portion of data, select a retransmission mode for the portion of data, from among at least:
a first mode that retransmits the portion of data on at least a second transmitter antenna of the plurality of transmitter antennas, while transmitting new data on at least the first transmitter antenna, the first mode being selected based on a particular level of delay being permissible;
a second mode that retransmits the portion of data on at least the first transmitter antenna, while transmitting the new data on at least the second transmitter antenna, the second mode being selected based on reducing delay below the particular level of delay;
a third mode that retransmits the portion of data on a transmitter antenna of the plurality of transmitter antennas that transmitted data that received an acknowledgement (ACK) during a previous transmission, without transmitting any data on the first transmitter antenna during the retransmission of the portion of data, the third mode being selected based on a particular error rate being permissible; and
a fourth mode that simultaneously retransmits the portion of data on each of the plurality of transmitter antennas, the fourth mode being selected based on reducing errors below the particular error rate.