Method and apparatus for performing random access
Systems, apparatuses, and methods for wireless communications are provided. A method may comprise receiving, by a wireless device from a base station, one or more messages comprising downlink control information (DCI) associated with a DCI format; determining that a first field of the DC corresponds to a predefined value, determining that, based on the first field corresponding to the predefined value, the DCI is for a random access procedure associated with a physical downlink control channel (PDCCH) order; determining, based on the determining that the DCI is for a random access procedure associated with a PDCCH order and based on a plurality of fields of the DCI, a random access channel (RACH) occasion; and transmitting, based on the RACH occasion, a random access preamble.
1. One or more non-transitory computer readable storage media encoded with instructions that, when executed by a processor, cause the processor to perform operations, comprising:
receiving, by a wireless device from a base station, one or more messages comprising downlink control information (DCI) associated with a DCI format;
determining that a field of the DCI corresponds to a predefined value;
determining, based on the field corresponding to the predefined value, the DCI is for random access associated with a physical downlink control channel (PDCCH) order, wherein a plurality of fields of the DCI comprise:
a synchronization signal/physical broadcasting channel (SS/PBCH) index field having a value indicating a SS/PBCH; and
a physical random access channel (PRACH) resource index field having a value indicating one or more random access channel (RACH) occasions; and
determining, based on the value of the SS/PBCH index field and the value of the PRACH resource index field, at least one RACH occasion, of the one or more RACH occasions, associated with the SS/PBCH; and
transmitting, based on the at least one RACH occasion associated with the SS/PBCH, a random access preamble.
2. The media of claim 1 , wherein the value indicating the SS/PBCH is associated with an index of the SS/PBCH.
3. The media of claim 1 , wherein the field corresponding to the predefined value is a frequency domain resource assignment field of DCI format 1_0.
4. The media of claim 1 , wherein the DCI format is DCI format 1_0 associated with a physical downlink shared channel (PDSCH) scheduling.
5. The media of claim 1 , wherein the instructions when executed by the processor, cause the processor to further perform operations, comprising:
determining the DCI based on a Cell Radio Network Temporary Identifier (C-RNTI).
6. The media of claim 1 , wherein the DCI further comprises an uplink/supplemental uplink (UL/SUL) indicator indicating an uplink carrier type associated with transmission of the random access preamble.
7. The media of claim 1 , wherein the instructions when executed by the processor, cause the processor to further perform operations, comprising:
determining, based on determining that the DCI is for random access associated with a PDCCH order, an uplink/supplemental uplink (ULUSUL) indicator of the plurality of fields of the DCI, wherein transmitting the random access preamble includes transmitting, based on the UL/SUL indicator, the random access preamble via an SUL carrier.
8. The media of claim 1 , wherein the instructions, when executed by the processor, cause the processor to perform further operations, comprising:
receiving, by the wireless device from the base station, an upper layer configuration message indicating a relationship between the SS/PBCH and a PRACH occasion.
9. The media of claim 8 , wherein the relationship indicates a number of synchronization signal blocks (SSBs) per PRACH occasion.
10. One or more non-transitory computer readable storage media encoded with instructions that, when executed by a processor, cause the processor to perform operations, comprising:
determining at least one random access channel (RACH) occasion for a wireless device, wherein the at least one RACH occasion for the wireless device is associated with a synchronization signal/physical broadcast channel (SS/PBCH);
generating downlink control information (DCI) corresponding to a DCI format, the DCI comprising:
a field having a predefined value indicating that the DCI is for random access associated with a physical downlink control channel (PDCCH) order;
an SS/PBCH index field having a value indicating the SS/PBCH; and
a physical RACH (PRACH) resource index field having a value indicating one or more RACH occasions, wherein the at least one RACH occasion for the wireless device is indicated to the wireless device by the value of the SS/PBCH index field and the value of the PRACH resource index field; and
transmitting the DCI to the wireless device to receive, from the wireless device and based on the at least one RACH occasion, a random access preamble.
11. The media of claim 10 , wherein the value indicating the SS/PBCH is associated with an index of the SS/PBCH.
12. The media of claim 10 , wherein the field having the predefined value is a frequency domain resource assignment field of DCI format 1_0.
13. The media of claim 10 , wherein the DCI format is DCI format 1_0 associated with a physical downlink shared channel (PDSCH) scheduling.
14. The media of claim 10 , wherein the instructions when executed by the processor, cause the processor to further perform operations, comprising:
generating second DCI for a physical downlink shared channel (PDSCH) scheduling, wherein the second DCI comprises a frequency domain resource assignment field having a value different from the predefined value; and
transmitting, to the wireless device, the second DCI.
15. The media of claim 10 , wherein the instructions when executed by the processor, cause the processor to further perform operations, comprising:
scrambling the DCI based on a Cell Radio Network Temporary Identifier (C-RNTI).
16. The media of claim 10 , wherein the DCI further comprises an uplink/supplemental uplink (UL/SUL) indicator indicating an uplink carrier type associated with transmission of the random access preamble.
17. One or more non-transitory computer readable storage media encoded with instructions that, when executed by a processor, cause the processor to perform operations, comprising:
receiving, from a base station, one or more messages comprising downlink control information (DCI);
determining that the DCI corresponds to DCI format 1_0;
determining that, based on a value of a field of the DCI, the DCI is for random access associated with a physical downlink control channel (PDCCH) order;
determining, based on a value of a synchronization signal/physical broadcast channel (SS/PBCH) index field of the DCI and based on a value of a physical random access channel (PRACH) resource index field associated with one or more random access channel (RACH) occasions, at least one RACH occasion associated with an SS/PBCH, wherein the SS/PBCH index field indicates the SS/PBCH; and
transmitting, based on the at least one RACH occasion associated with the SS/PBCH, a random access preamble.
18. The media of claim 17 , wherein the value of the SS/PBCH index field indicates an index of the SS/PBCH.
19. The media of claim 17 , wherein the value of the field of the DCI is a predefined value of a frequency domain resource assignment field of the DCI.
20. The media of claim 17 , wherein the instructions when executed by the processor, cause the processor to further perform operations, comprising:
receiving second DCI corresponding to the DCI format 1_0, and
determining that a frequency domain resource assignment field of the second DCI has a value different from a predefined value, and to retrieve, from the second DCI, information of a physical downlink shared channel (PDSCH) scheduling, wherein the predefined value is associated with random access associated with a PDCCH order.
21. The media of claim 17 , wherein the instructions when executed by the processor, cause the processor to further perform operations, comprising:
determining the DCI based on a Cell Radio Network Temporary Identifier (C-RNTI).
22. The media of claim 17 , wherein the DCI further comprises an uplink/supplemental uplink (UL/SUL) indicator indicating an uplink carrier type associated with transmission of the random access preamble.
23. The media of claim 17 , wherein the instructions when executed by the processor, cause the processor to further perform operations, comprising:
receiving, from the base station, configuration information comprising one or more of:
a PRACH configuration period;
a transmission SS/PBCH block-PRACH mapping configuration period; or
a number of SS/PBCH blocks per RACH occasion.