Polar coding system for ultra-reliable low latency communication
Systems, methods, and instrumentalities are described herein for supporting CBG-based retransmission with variable CBG size using variable length HARQ-ACK. A WTRU may receive a configuration to use a first table. The first table may be associated with a maximum number of code block groups per transport block (maxCBG/TB). The WTRU may determine a number of HARQ-ACK bits to send for code blocks. The determination may depend on whether an indication is received to switch from the first table to a second table. On a condition that the indication to switch from the first table to the second table is received, the WTRU may send a number of HARQ-ACK bits that is equal to two times the maxCBG/TB. The WTRU may receive a retransmission of a number of code blocks, wherein a code block group size depends on a sent number of HARQ-ACK bits.
1. A wireless transmit/receive unit (WTRU), comprising:
a processor configured at least in part to:
receive configuration information indicating a first and a second modulation and coding scheme (MCS) tables;
receive a transport block comprising code block groups;
determine a number of hybrid automatic repeat request acknowledgement (HARQ-ACK) bits to send for the received code block groups, wherein the number of HARQ-ACK bits to send is determined based on whether an indication is received to switch from the first MCS table to the second MCS table;
decode code blocks associated with the transport block according to the received indication; and
send a HARQ-ACK feedback having the determined number of HARQ-ACK bits.
2. The WTRU of claim 1 , further comprising:
on a condition that the indication to switch from the first MCS table to the second MCS table is not received or there is no decoding error, the processor is further configured to send HARQ-ACK bits wherein the number of HARQ-ACK bits is equal to a maximum number of code block groups per transport block (maxCBG/TB); and
on a condition that the indication to switch from the first MCS table to the second MCS table is received and there is a decoding error, the processor is further configured to send HARQ-ACK bits wherein the number of HARQ-ACK bits is equal to two times the maxCBG/TB.
3. The WTRU of claim 2 , wherein on the condition that the indication to switch from the first MCS table to the second MCS table is received and there is the decoding error, a number of HARQ-ACK bits are generated by equally splitting code block groups.
4. The WTRU of claim 1 , wherein the processor is further configured to receive a retransmission of a number of code blocks, wherein the retransmitted number of code blocks is associated with the sent number of HARQ-ACK bits.
5. The WTRU of claim 3 , wherein:
on a condition that the sent number of HARQ-ACK bits is equal to a maximum number of code block groups per transport block (maxCBG/TB), the retransmitted number of code blocks equals a number of code blocks in the transport block divided by the maxCBG/TB; or
on a condition that the sent number of HARQ-ACK bits is equal to two times the maxCBG/TB, the retransmitted number of code blocks is equal to half a value of: the number of code blocks in the transport block divided by the maxCBG/TB.
6. The WTRU of claim 1 , wherein on the condition that the indication to switch from the first MCS table to the second MCS table is received, the indication is indicated by a radio network temporary identifier (RNTI), and wherein the RNTI is masked with bits of a cyclic redundancy check of downlink control information.
7. The WTRU of claim 1 , wherein the processor is further configured to select an MCS table based on the received indication, and, use the selected MCS table to decode code blocks.
8. The WTRU of claim 7 , wherein the processor is further configured to perform channel quality indicator (CQI) estimation and report CQI based on a CQI table for a lower block error rate target, wherein a lowest code rate in the CQI table is 30/1024.
9. A method comprising:
receiving configuration information indicating a first and a second modulation and coding scheme (MCS) tables;
receiving a transport block comprising code block groups;
determining a number of hybrid automatic repeat request acknowledgement (HARQ-ACK) bits to send for the received code block groups, wherein the number of HARQ-ACK bits to send is determined based on whether an indication is received to switch from the first MCS table to the second MCS table;
decoding code blocks associated with the transport block according to the received indication; and
sending a HARQ-ACK feedback having the determined number of HARQ-ACK bits.
10. The method of claim 9 , further comprising:
on a condition that the indication to switch from the first MCS table to the second MCS table is not received or there is no decoding error, the method further comprises sending HARQ-ACK bits wherein the number of HARQ-ACK bits is equal to a maximum number of code block groups per transport block (maxCBG/TB); or
on a condition that the indication to switch from the first MCS table to the second MCS table is received and there is a decoding error, the method further comprises sending HARQ-ACK bits wherein the number of HARQ-ACK bits is equal to two times the maxCBG/TB.
11. The method of claim 10 , wherein on the condition that the indication to switch from the first MCS table to the second MCS table is received and there is the decoding error, a number of HARQ-ACK bits are generated based on equally splitting code block groups.
12. The method of claim 9 , further comprising receiving a retransmission of a number of code blocks, wherein the retransmitted number of code blocks is associated with the sent number of HARQ-ACK bits.
13. The method of claim 12 , wherein:
on a condition that the sent number of HARQ-ACK bits is equal to a maximum number of code block groups per transport block (maxCBG/TB), the retransmitted number of code blocks equals a number of code blocks in the transport block divided by the maxCBG/TB; or
on a condition that the sent number of HARQ-ACK bits is equal to two times the maxCBG/TB, the retransmitted number of code blocks is equal to half a value of: the number of code blocks in the transport block divided by the maxCBG/TB.
14. The method of claim 9 , wherein on the condition that the indication to switch from the first MCS table to the second MCS table is received, the indication is indicated by an a radio network temporary identifier (RNTI), and wherein the RNTI is masked with bits of a cyclic redundancy check of downlink control information.
15. The method of claim 9 , wherein the method further comprises selecting an MCS table based on the received indication, and, using the selected MCS table to decode code blocks.
16. The method of claim 15 , wherein the method further comprises performing channel quality indicator (CQI) estimation and reporting CQI based on a CQI table for a lower block error rate target, wherein a lowest code rate in the CQI table is 30/1024.