HARQ transmission scheme using multiple parallel HARQ threads
Embodiments described herein provide apparatus and methods for performing HARQ operations using parallel HARQ threads, where each new transmission of a MPDU/A-MPDU/PSDU triggers the activation of a HARQ thread. Each HARQ thread contains one or more HARQ coding words or coding units. A HARQ thread index is setup by a transmission opportunity (TXOP) holder for a corresponding PSDU and is used to identify HARQ threads. Multiple HARQ threads can be aggregated into one PPDU for transmission (or retransmission). The maximum number of HARQ threads can be negotiated between AP and non-AP STAs based on buffer requirements, for example. A HARQ thread can end when all MPDUs associated with the HARQ thread have been decoded or other predetermined conditions are met.
1. A method of retransmitting data using a hybrid automatic repeat request (HARQ) thread, the method comprising:
receiving an acknowledgement associated with a prior data transmission indicating missed data of the prior data transmission for a first HARQ thread associated with a first HARQ thread index value; and
based on the acknowledgment, transmitting a Physical Layer Convergence Procedure (PLCP) Protocol Data Unit (PPDU) comprising:
a plurality of HARQ threads comprising the first HARQ thread;
a HARQ SIG field indicating thread information for the plurality of HARQ threads, wherein the thread information comprises a number of orthogonal frequency-division multiplexing (OFDM) symbol segments for the plurality of HARQ threads;
a first HARQ retransmission for the first HARQ thread;
a new data transmission associated with an index value of a second HARQ thread of the plurality of HARQ threads; and
a PHY header identifying the first HARQ thread index value and the second HARQ thread index value.
2. The method of claim 1 , wherein the missed data of the prior data transmission comprises HARQ coding units corresponding to missed HARQ coding units.
3. The method of claim 1 , wherein the new data transmission comprises a PLCP Service Data Unit (PSDU) for a second HARQ thread.
4. The method of claim 1 , wherein the PPDU further comprises a second HARQ retransmission for a second HARQ thread.
5. The method of claim 1 , further comprising receiving a second acknowledgement comprising a block acknowledgement (BA) for received PSDUs.
6. The method of claim 1 , wherein the PPDU further comprises a plurality of HARQ threads, and the acknowledgement comprises:
a block acknowledgement (BA) indicating received Media Access Control (MAC) Protocol Data Units (MPDUs) for the plurality of HARQ thread; and
HARQ coding unit feedback for the plurality of HARQ threads.
7. The method of claim 1 , wherein the acknowledgement comprises at least one of: a HARQ acknowledgment type indication set in a BA control field; a HARQ thread index indication for retransmission; and a HARQ coding unit indication for retransmission.
8. The method of claim 7 , wherein the HARQ coding unit indication comprises a HARQ thread bitmap.
9. The method of claim 1 , wherein the HARQ thread information further comprises HARQ thread transmission parameters for the plurality of HARQ threads.
10. A method of providing hybrid automatic repeat request (HARQ) feedback responsive to a HARQ transmission, the method comprising:
receiving a Physical Layer Convergence Procedure (PLCP) Protocol Data Unit (PPDU) comprising at least one of:
a HARQ retransmission for a first HARQ thread associated with a first HARQ thread index value;
a new data transmission associated with a second HARQ thread associated with a second HARQ thread index value;
a PHY header indicating the first HARQ thread index value and the second HARQ thread index value; and
a HARQ SIG field indicating thread information for the first and second HARQ threads, wherein the thread information comprises a number of orthogonal frequency-division multiplexing (OFDM) symbol segments for the first and second HARQ threads; and
transmitting an acknowledgment responsive to receiving the PPDU, wherein the acknowledgment indicates at least one of:
MPDUs of HARQ threads that are acknowledged;
HARQ coding units of the HARQ threads that require HARQ retransmission; and
no HARQ coding units of the HARQ threads are acknowledged (NACK).
11. The method of claim 10 , wherein the PPDU further comprises a second HARQ retransmission for a third HARQ thread, and wherein the acknowledgment indicates acknowledged MPDUs of at least one of: the first HARQ thread; the second HARQ thread; and the third HARQ thread.
12. The method of claim 10 , further comprising receiving a second PPDU comprising a second retransmission for the first HARQ thread, a first retransmission for the second HARQ thread, and a second new data transmission for a third HARQ thread, wherein the second PPDU is transmitted responsive to a device receiving the acknowledgment.
13. The method of claim 10 , wherein the acknowledgement comprises:
a block acknowledgement (BA) indicating received Media Access Control (MAC) Protocol Data Units (MPDUs) for the HARQ thread; and
HARQ coding unit feedback for the HARQ threads.
14. The method of claim 10 , wherein the acknowledgement comprises at least one of: a HARQ acknowledgment type indication set in a BA control field; a HARQ thread index indication for retransmission; and a HARQ coding unit indication for retransmission.
15. The method of claim 14 , wherein the HARQ coding unit indication comprises a HARQ thread bitmap.
16. A device for performing hybrid automatic repeat request (HARQ) retransmission in a wireless network, the device comprising:
a transceiver configured to send and receive data on the wireless network;
a memory; and
a processor operable to cause the transceiver to:
receive an acknowledgement associated with a prior data transmission indicating missed data of the prior data transmission for a first HARQ thread associated with a first HARQ thread index value, wherein decoded data of the prior data transmission is stored in the memory; and
based on the acknowledgment, transmit a response Physical Layer Convergence Procedure (PLCP) Protocol Data Unit (PPDU) comprising:
a first HARQ retransmission for the first HARQ thread;
a new data transmission;
a PHY header identifying the first HARQ thread index value and the second HARQ thread index value; and
a HARQ SIG field indicating thread information for the first and second HARQ threads, wherein the thread information comprises a number of orthogonal frequency-division multiplexing (OFDM) symbol segments for the first and second HARQ threads.
17. The device of claim 16 , wherein the PPDU further comprises a plurality of HARQ threads, and the acknowledgement comprises:
a block acknowledgement (BA) indicating received Media Access Control (MAC) Protocol Data Units (MPDUs) for the plurality of HARQ threads; and
HARQ coding unit feedback for the plurality of HARQ threads.
18. The device of claim 16 , wherein the acknowledgement comprises at least one of: a HARQ acknowledgment type indication set in a BA control field; a HARQ thread index indication for retransmission; and a HARQ coding unit indication for retransmission.
19. The device of claim 18 , wherein the HARQ coding unit indication comprises a HARQ thread bitmap.