Random access response reception for a two-step random access procedure

1. A method comprising:

transmitting, by a wireless device, a first message comprising:

a preamble; and

a transport block comprising a contention resolution identifier of the wireless device;

receiving downlink control information indicating:

a first slot offset in an allocation table; and

a first start symbol number in the allocation table;

receiving, via a first slot determined based on the first slot offset and the first start symbol number, a first response of the first message, wherein the first response comprises the contention resolution identifier and indicates:

a second slot offset in the allocation table; and

a second start symbol number in the allocation table;

determining, for receiving a second response of the first message, a second slot based on:

the second slot offset starting with respect to the first slot; and

a time offset for the second response; and

receiving the second response from a start symbol of the second slot, wherein the start symbol is determined based on the second start symbol number.

2. The method of claim 1 , wherein the allocation table is predefined for a two-step random access procedure.

3. The method of claim 1 , wherein:

the downlink control information indicates a first row of the allocation table, the first row indicating the first slot offset and the first start symbol number; and

the first response further indicates a second row of the allocation table, the second row indicating the second slot offset and the second start symbol number.

4. The method of claim 1 , wherein the time offset is defined based on at least one of:

one or more symbols; and

one or more slots.

5. The method of claim 1 , wherein the time offset is predefined or semi-statically configured.

6. The method of claim 1 , further comprising determining, based on a first numerology used for receiving the first response, at least one of one or more values as the time offset, the at least one of the one or more values being associated with the first numerology.

7. The method of claim 1 , further comprising receiving random access configuration parameters for a two-step random access procedure, wherein the random access configuration parameters indicate:

at least one random access channel for a transmission of the preamble; and

at least one uplink channel for a transmission of the transport block.

8. The method of claim 7 , further comprising determining a random access identifier used for receiving the downlink control information based on one or more time and frequency resource indices of the at least one random access channel.

9. The method of claim 1 , further comprising determining that the first response corresponds to the first message based on the first response further comprising at least one of:

a preamble identifier of the preamble; and

the contention resolution identifier.

10. A wireless device comprising:

one or more processors; and

memory storing instructions that, when executed by the one or more processors, cause the wireless device to:

transmit a first message comprising:

a preamble; and

a transport block comprising a contention resolution identifier of the wireless device;

receive downlink control information indicating:

a first slot offset in an allocation table; and

a first start symbol number in the allocation table;

receive, via a first slot determined based on the first slot offset and the first start symbol number, a first response of the first message, wherein the first response comprises the contention resolution identifier and indicates:

a second slot offset in the allocation table; and

a second start symbol number in the allocation table;

determine, for receiving a second response of the first message, a second slot based on:

the second slot offset starting with respect to the first slot; and

a time offset for the second response; and

receive the second response from a start symbol of the second slot, wherein the start symbol is determined based on the second start symbol number.

11. The wireless device of claim 10 , wherein the allocation table is predefined for a two-step random access procedure.

12. The wireless device of claim 10 , wherein:

the downlink control information indicates a first row of the allocation table, the first row indicating the first slot offset and the first start symbol number; and

the first response further indicates a second row of the allocation table, the second row indicating the second slot offset and the second start symbol number.

13. The wireless device of claim 10 , wherein the time offset is predefined or semi-statically configured.

14. The wireless device of claim 10 , wherein the instructions, when executed by the one or more processors, further cause the wireless device to determine, based on a first numerology used for receiving the first response, at least one of one or more values as the time offset, the at least one of the one or more values being associated with the first numerology.

15. The wireless device of claim 10 , wherein the instructions, when executed by the one or more processors, further cause the wireless device to receive random access configuration parameters for a two-step random access procedure, the random access configuration parameters indicating:

at least one random access channel for a transmission of the preamble; and

at least one uplink channel for a transmission of the transport block.

16. The wireless device of claim 15 , wherein the instructions, when executed by the one or more processors, further cause the wireless device to determine a random access identifier used for receiving the downlink control information based on one or more time and frequency resource indices of the at least one random access channel.

17. The wireless device of claim 10 , wherein the instructions, when executed by the one or more processors, further cause the wireless device to determine that the first response corresponds to the first message based on the first response further comprising at least one of:

a preamble identifier of the preamble; and

the contention resolution identifier.

18. A system comprising:

a base station comprising:

one or more first processors; and

first memory storing first instructions that, when executed by the one or more first processors, cause the base station to:

receive a first message comprising:

a preamble; and

a transport block comprising a contention resolution identifier of a wireless device;

transmit downlink control information indicating:

a first slot offset in an allocation table; and

a first start symbol number in the allocation table;

transmit, via a first slot determined based on the first slot offset and the first start symbol number, a first response of the first message, wherein the first response comprises the contention resolution identifier and indicates:

a second slot offset in the allocation table; and

a second start symbol number in the allocation table; and

transmit a second response from a start symbol of the second slot, wherein the start symbol is determined based on the second start symbol number; and the wireless device comprising:

one or more second processors; and

second memory storing second instructions that, when executed by the one or more second processors, cause the wireless device to:

transmit the first message;

receive the downlink control information;

receive, via the first slot, the first response of the first message;

determine, for receiving the second response of the first message, a second slot based on:

the second slot offset starting with respect to the first slot; and

a time offset for the second response; and

receive the second response from a start symbol of the second slot.