Extension carrier for ARQ
According to one or more embodiments described and claimed herein, HARQ acknowledgements, re-transmissions, and related signaling (e.g., channel quality reports) are performed on a Re-transmission Extension Carrier (REC) separate from the primary downlink traffic carrier(s). In various embodiments, as explained herein, the REC may comprise an aggregated wireless communication network channel, which may be cross-channel scheduled or may have its own scheduler. The REC may be Frequency Domain Duplex (FDD) or Time Domain Duplex (TDD). The REC may be dedicated to a main downlink carrier, or may be shared across a plurality of aggregated component carriers. The REC may be transmitted from the same base station as one or more associated main carriers, or from a different base station. A shared REC may be operated in cooperative or contention modes. The REC may be implemented in unlicensed spectrum.
1. A method of operating a base station, comprising:
receiving data to be transmitted to one or more User Equipment (UE);
scheduling base station transmission of at least one block of the data to a UE of the one or more UE in a first scheduler;
transmitting, by the base station, the at least one block of the data to the UE on at least a first component carrier (CC), wherein the base station implements carrier aggregation;
receiving, at the base station, a negative acknowledgement (NAK) from the UE indicating one or more errors in at least one received data block; and
re-transmitting at least one block of the data to the UE on a dedicated Re-transmission Extension Carrier (REC) that is a CC separate from any CC on which the at least one block of the data was transmitted to the UE, wherein the REC transmits only Automatic Repeat Request (ARQ) and/or Hybrid ARQ (HARQ) retransmission data at all times.
2. The method of claim 1 wherein re-transmitting the block of data to the UE on REC comprises cross-carrier scheduling the re-transmission on the REC from the first CC.
3. The method of claim 1 further comprising, prior to re-transmitting the block of data:
sending information about the re-transmission and the UE to a second scheduler associated with the REC.
4. The method of claim 1 further comprising, prior to re-transmitting the block of data:
monitoring the REC for an ongoing transmission; and
re-transmitting the block of data to the UE on the REC only if there is no transmission ongoing on the REC.
5. The method of claim 1 further comprising:
receiving a channel quality indicator from the UE on the REC.
6. The method of claim 5 wherein downlink and uplink transmissions on the REC are Frequency Division Duplexed (FDD).
7. The method of claim 5 wherein downlink and uplink transmissions on the REC are Time Division Duplexed (TDD).
8. The method of claim 1 wherein the REC is a carrier in unlicensed spectrum.
9. The method of claim 8 further comprising, prior to re-transmitting the block of data:
monitoring the REC for an ongoing transmission; and
re-transmitting the block of data to the UE on the REC only if there is no transmission ongoing on the REC.
10. The method of claim 8 further comprising, prior to re-transmitting the block of data:
adding interference mitigation to a signal to be transmitted.
11. The method of claim 10 wherein the interference mitigation comprises encoding the block of data at a lower coding rate.
12. The method of claim 10 wherein the interference mitigation comprises spreading the transmission over wider frequency/time resources using spread spectrum techniques.
13. The method of claim 10 wherein the interference mitigation comprises applying transmitter side beam-forming to the intended receivers.
14. The method of claim 1 wherein the base station is capable of performing Multiple Input Multiple Output (MIMO) transmissions, and
wherein receiving a NAK from the UE comprises receiving a NAK associated with each block of data transmitted, and
wherein re-transmitting the at least one block of the data to the UE on a REC comprises re-transmitting each block of data associated with a NAK.
15. The method of claim 1 wherein the base station is capable of performing Multiple Input Multiple Output (MIMO) transmissions, and
wherein receiving a NAK from the UE comprises receiving a single NAK indicating an error in at least one block of data, and
wherein re-transmitting the at least one block of the data to the UE on a REC comprises re-transmitting all blocks of data in response to the single NAK.
16. A method of transmitting HARQ re-transmissions on a dedicated Re-transmission Extension Carrier (REC), comprising:
receiving, by a first base station, at least one block of data to be transmitted to one or more User Equipment (UE);
scheduling first base station transmission of the at least one block of data to a first UE of the one or more UE in a first scheduler;
transmitting, by the first base station, the at least one block of data to the first UE on at least a first component carrier (CC), wherein the base station implements carrier aggregation;
receiving, at the first base station, a negative acknowledgement (NAK) from the UE indicating one or more errors in at least one received data block;
receiving, at a second base station, a first block of the data previously transmitted, by the first base station, to the first UE on the first CC, the previous transmission having been negatively acknowledged (NAK) by the first UE as containing one or more errors; and
transmitting, by the second base station, the first block of the data to the first UE on the REC that is separate from any CC on which the data was previously transmitted to the first UE from the first base station, wherein only Automatic Repeat Request (ARQ) and/or Hybrid ARQ (HARQ) retransmission data is transmitted on the REC at all times.
17. The method of claim 16 further comprising:
receiving a second block of data previously transmitted to a second UE on a second carrier other than the REC, the previous transmission having been negatively acknowledged (NAK) by the second UE as containing one or more errors;
scheduling the transmission of the first block of data to the first UE on the REC;
scheduling the transmission of the second block of data to the second UE on the REC; and
transmitting the second block of data to the second UE on the REC.
18. The method of claim 17 wherein scheduling the transmission of the first block of data to the first UE and the second block of data on the second UE on the REC comprises sharing REC bandwidth equally between the first and second blocks of data.
19. The method of claim 17 further comprising:
receiving a first channel quality indicator from the first UE; and
receiving a second channel quality indicator from the second UE;
wherein scheduling the transmission of the first block of data to the first UE on the REC and scheduling the transmission of the second block of data on the second UE on the REC, comprises scheduling the transmissions in response to the received first and second channel quality indicators.
20. A base station operative in a wireless communication network, comprising:
a first transceiver operative to transmit data to one or more User Equipment (UE) on at least a first component carrier (CC);
a network interface operative to exchange data with one or more network nodes;
memory; and
a controller operatively connected to the memory, the transceiver, and the network interface, and operative to:
receive, via the network interface, data to be transmitted to the one or more UE;
implement carrier aggregation;
schedule transmission of at least one block of data to a UE of the one or more UE on at least the first CC;
cause the first transceiver to transmit the at least one block of the data to the UE on at least the first CC;
receive, from the transceiver, a negative acknowledgement (NAK) from the UE indicating one or more errors in the received data block; and
cause at least one block of data to be re-transmitted to the UE on a dedicated Re-transmission Extension Carrier (REC) that is a CC separate from any CC on which the at least one block of data was transmitted to the UE, wherein the REC transmits only Automatic Repeat Request (ARQ) and/or Hybrid ARQ (HARQ) retransmission data at all times.
21. The base station of claim 20 , further comprising:
a second transceiver operative to transmit data to UE on a Re-transmission Extension Carrier (REC) separate from any CC on which a block of data was transmitted to the UE; and
wherein the controller is operative to cause the at least one block of the data to be re-transmitted to the UE by causing the second transceiver to transmit at least one block of data to the UE on the REC.
22. The base station of claim 21 wherein the controller is further operative to schedule transmission of the at least one block of data to the UE on the REC.
23. The base station of claim 22 wherein the controller is further operative to schedule on the REC the transmission of one or more blocks of data to be re-transmitted to other UE as a result of the other UE having NAK'ed a downlink transmission of data on other CCs.
24. The base station of claim 21 wherein the controller is further operative to monitor the REC for an ongoing transmission; and
cause the second transceiver to transmit the at least one block of data to the UE on the REC only if there is no transmission ongoing on the REC.
25. The base station of claim 20 wherein
the controller is operative to cause the at least one block of data to be re-transmitted to the UE by sending the at least one block of data, via the network interface, to a network node operative to transmit the at least one block of data to the UE on a Re-transmission Extension Carrier (REC).
26. The base station of claim 20 further comprising:
a third transceiver operative to transmit data to UE in unlicensed spectrum; and
wherein the controller is operative to cause the at least one block of data to be re-transmitted to the UE by causing the third transceiver to transmit the at least one block of data to the UE in unlicensed spectrum.
27. The base station of claim 26 wherein the controller is further operative to monitor the unlicensed spectrum for an ongoing transmission; and
cause the third transceiver to transmit the at least one block of data to the UE in unlicensed spectrum only if there is no transmission ongoing in the unlicensed spectrum.
28. The base station of claim 26 wherein the controller is further operative to
add interference mitigation to a signal to be transmitted.
29. User Equipment operative in a wireless communication network, comprising:
a transceiver operative to receive and transmit data from and to a base station on a first component carrier (CC), wherein the base station implements carrier aggregation;
memory; and
a controller operatively connected to the memory and the transceiver, and operative to receive, from the transceiver, data transmitted by the base station on the first CC, wherein the data comprises at least one block of data;
perform error detection on the received data;
in the case of a detected error, cause the transceiver to transmit a negative acknowledgement (NAK) to the base station on the first CC; and
receive, from the transceiver, a re-transmission of the erroneous data on a dedicated Re-transmission Extension Carrier (REC) that is a CC separate from any CC on which the at least one block of data was transmitted to the UE, wherein the REC transmits only HARQ/ARQ retransmission data at all times.
30. The UE of claim 29 wherein the controller is operative to receive the re-transmission in unlicensed spectrum.