Skipping uplink transmission allocated by RACH procedure

1. An apparatus comprising:

a transceiver of the apparatus that receives during a random access procedure (“RACH procedure”), a random access response (“RAR”) message, sent by a base station operating on an unlicensed carrier and having determined via listen-before-talk that the channel is clear, the RAR message comprising an RAR grant having an uplink resource allocation for the RACH procedure;

a processor of the apparatus that determines an indication that skipping of an uplink transmission is configured for the RACH procedure, the indication explicitly communicated for the RACH procedure by the base station on the unlicensed carrier; and

wherein the processor controls the transceiver to perform one or more actions selected from skipping the uplink transmission and skipping the generation of a transport block (“TB”) without logical channel (“LCH”) data on the uplink resource allocation in response to determining the indication that skipping is configured for the RACH procedure and further determining that no uplink data is available.

2. The apparatus of claim 1 , wherein the indication that skipping is configured for the RACH procedure comprises determining that the uplink grant was addressed to a Radio Network Temporary Identifier (“RNTI”), the RNTI selected from a Temporary Cell RNTI (“Temporary C-RNTI”) and a Random Access RNTI (“RA-RNTI”).

3. The apparatus of claim 2 , wherein the indication that skipping is configured for the RACH procedure comprises the uplink resources corresponding to the uplink grant being allocated on the unlicensed carrier.

4. The apparatus of claim 2 , wherein the indication that skipping is configured for the RACH procedure comprises data within the RAR message.

5. The apparatus of claim 2 , wherein the indication that skipping is configured for the RACH procedure comprises data within downlink control information (“DCI”) scheduling the RAR message on a downlink shared channel (“DL-SCH”).

6. The apparatus of claim 2 , wherein the indication that skipping is configured for the RACH procedure comprises a higher layer signaling parameter that configures the remote unit for skipping the uplink transmission.

7. The apparatus of claim 1 , wherein the processor further:

receives a retransmission request corresponding to the RAR message; and

controls the transceiver to skip the retransmission in response to the retransmission request being scheduled by DCI addressed to a Temporary Cell RNTI of the remote unit.

8. The apparatus of claim 1 , wherein the processor further:

receives a retransmission request corresponding to the RAR message; and

controls the transceiver to transmit a TB in response to the retransmission request being scheduled by DCI addressed to a Temporary Cell RNTI of the remote unit.

9. The apparatus of claim 1 , wherein the indication that skipping is configured for the RACH procedure further explicitly indicates to the remote to not generate the TB without LCH data.

10. The apparatus of claim 9 , wherein the indication that skipping is configured for the RACH procedure comprises a predefined combination of values within one or more fields of the RAR grant.

11. The apparatus of claim 10 , wherein the predefined combination of values comprises an invalid value in a resource allocation of the RAR grant.

12. The apparatus of claim 11 , wherein the resource allocation of the RAR grant is selected from a Msg3 physical uplink shared channel (“PUSCH”) frequency allocation and a PUSCH time resource allocation.

13. The apparatus of claim 9 , wherein the indication that explicitly indicates to the remote unit to skip the uplink transmission and/or to not generate the TB without LCH data is received in a Reserved (“R”) bit of the RAR message.

14. The apparatus of claim 13 , wherein in response to the R bit being not set, the processor:

controls the transceiver to skip the uplink transmission on the uplink resource of the grant; and

processes one or more other commands in fields of the RAR message other than a grant field.

15. The apparatus of claim 1 , wherein the processor further controls the transceiver to transmit an aperiodic sounding reference signal (“SRS”) to indicate acknowledgment of the RAR during the RACH procedure in which skipping is configured and no uplink data is available.

16. The apparatus of claim 15 , wherein a request to transmit the SRS is conveyed in an uplink grant field of the RAR message.

17. The apparatus of claim 15 , wherein a resource allocation for the SRS transmission is configured using a higher layer signaling parameter.

18. The apparatus of claim 15 , wherein the SRS is transmitted on the uplink resource allocation for the uplink transmission.

19. The apparatus of claim 15 , wherein a resource allocation for the SRS transmission comprises a parameter in the RAR message separate from the uplink resource allocation in the RAR grant.

20. The apparatus of claim 15 , wherein the processor further controls the transceiver to perform a shortened clear channel assessment (“Type II CCA”) for the SRS transmission.

21. The apparatus of claim 1 , wherein the processor further controls the transceiver to transmit a hybrid automatic repeat request (“HARQ”) acknowledgment (“ACK”) message to indicate acknowledgment of the RAR during the RACH procedure in which skipping is configured and no uplink data is available.

22. The apparatus of claim 21 , wherein the transceiver transmits the HARQ ACK on a Physical Uplink Control Channel (“PUCCH”) resource.

23. The apparatus of claim 21 , wherein the processor further controls the transceiver to perform a shortened clear channel assessment (“Type II CCA”) for the transmission of the HARQ ACK.

24. A method for a remote unit comprising:

receiving a random access response (“RAR”) message from a base station operating on an unlicensed carrier and having determined via listen-before-talk that the channel is clear, the RAR message comprising an RAR grant having an uplink resource allocation during a random access procedure (“RACH procedure”);

receiving an indication that skipping of an uplink transmission is configured for the RACH procedure, the indication explicitly communicated for the RACH procedure by the base station on the unlicensed carrier; and

skipping one or more actions selected from: performing the uplink transmission; and generating a transport block (“TB”) without logical channel (“LCH”) data on the uplink resource allocation, in response to receiving the indication that skipping is configured for the RACH procedure and in further response to determining that no uplink data is available.