Reference signal scrambling for random access

1. A method at a network device for scrambling a downlink reference signal for a user equipment (UE) for demodulation of a downlink random access message, the method comprising:

during a random access procedure to the network device, scrambling, by the network device, the downlink reference signal using an identifier (ID),

wherein the ID is a temporary UE ID provided to the UE during the random access procedure,

wherein the ID is a random access ID generated during the random access procedure, or

wherein the ID is a dedicated UE ID assigned by the network device, and the random access procedure is a contention-free random access procedure.

2. The method of claim 1 , wherein the downlink random access message is at least one of:

a random access response message; or

a contention resolution message.

3. The method of claim 1 , wherein the random access ID is generated based on at least one of:

a random access preamble; or

time and frequency resources used by the UE.

4. The method of claim 1 wherein the random access ID comprises a random access identifier generated based on a synchronization signal (SS) block index of an SS block within a set of SS blocks.

5. The method of claim 1 wherein the random access ID comprises a random access identifier generated based on an SS block time index associated with one or more SS blocks.

6. The method of claim 1 , wherein the random access ID comprises a random access radio network temporary identifier (RA-RNTI) generated as

RA-RNTI=1 +t_id+N _subframe* f _id+ SS _block+ N _ SS _Block* SS _block_time_index

wherein

RA-RNTI is the random access ID,

t_id is an index of a subframe of a plurality of subframes, N_subframe, of a physical random access channel (PRACH),

f_id is an index in a frequency domain of the PRACH within the subframe,

SS_block indicates an SS block index of an SS block within a set of concurrently transmitted SS blocks,

SS_block_time_index is an index ranging from 0 to N_SS_Block−1, and

N_SS_Block is a maximum number of SS blocks concurrently transmitted per SS block time index.

7. A method for demodulation of a downlink random access response (RAR) message by a user equipment (UE), the method comprising:

during a random access procedure for access of the UE to a network device, receiving, by the UE, a downlink reference signal scrambled using an identifier (ID),

wherein the ID is a temporary UE ID provided to the UE during the random access procedure,

wherein the ID is a random access ID generated during the random access procedure, or wherein the ID is a dedicated UE ID assigned by the network device, and the random access procedure is a contention-free random access procedure; and

demodulating the downlink RAR message using the downlink reference signal.

8. The method of claim 7 , wherein the random access ID is a random access radio network temporary identifier (RA-RNTI) generated based on at least one of a random access preamble used by the UE in the random access procedure or time and frequency resources used by the UE in the random access procedure.

9. The method of claim 7 , wherein the random access ID is derived in accordance with a synchronization signal transmitted by the network device.

10. The method of claim 7 wherein the identifier comprises a random access identifier generated based on a synchronization signal (SS) block index of an SS block within a set of SS blocks.

11. The method of claim 7 wherein the identifier comprises a random access identifier generated based on an SS block time index associated with one or more SS blocks.

12. The method of claim 7 , wherein the identifier comprises an RA-RNTI generated as

RA-RNTI=1 +t_id+N _subframe* f _id+ SS _block+ N _ SS _Block* SS _block_time_index

wherein

RA-RNTI is a random access identifier,

t_id is an index of a subframe of a plurality of subframes, N_subframe, of a physical random access channel (PRACH),

f_id is an index in a frequency domain of the PRACH within the subframe,

SS_block indicates an SS block index of an SS block within a set of concurrently transmitted SS blocks,

SS_block_time_index is an index ranging from 0 to N_SS_Block−1, and

N_SS_Block is a maximum number of SS blocks concurrently transmitted per SS block time index.

13. A network device comprising:

a non-transitory memory storage containing instructions; and

one or more processors in communication with the non-transitory memory storage, wherein the one or more processors execute the instructions to:

scramble a downlink reference signal for a user equipment (UE) for demodulation of a downlink random access message during a random access procedure to the network device using an identifier (ID),

wherein the ID is a temporary UE ID provided to the UE during the random access procedure,

wherein the ID is a random access ID generated during the random access procedure, or

wherein the ID is a dedicated UE ID assigned by the network device, and the random access procedure is a contention-free random access procedure.

14. The network device of claim 13 , wherein the downlink random access message is at least one of:

a random access response message; or

a contention resolution message.

15. The network device of claim 13 , wherein the random access ID is generated based on at least one of:

a random access preamble; or

time and frequency resources used by the UE.

16. The network device of claim 13 wherein the random access ID comprises a random access identifier generated based on a synchronization signal (SS) block index of an SS block within a set of SS blocks.

17. The network device of claim 13 wherein the random access ID comprises a random access identifier generated based on an SS block time index associated with one or more SS blocks.

18. The network device of claim 13 , wherein the random access ID comprises a random access radio network temporary identifier (RA-RNTI) generated as

RA-RNTI=1 +t_id+N _subframe* f _id+ SS _block+ N _ SS _Block* SS _block_time_index

wherein

RA-RNTI is the random access ID,

t_id is an index of a subframe of a plurality of subframes, N_subframe, of a physical random access channel (PRACH),

f_id is an index in a frequency domain of the PRACH within the subframe,

SS_block indicates an SS block index of an SS block within a set of concurrently transmitted SS blocks,

SS_block_time_index is an index ranging from 0 to N_SS_Block−1, and

N_SS_Block is a maximum number of SS blocks concurrently transmitted per SS block time index.

19. A user equipment (UE) comprising:

a non-transitory memory storage containing instructions; and

one or more processors in communication with the non-transitory memory storage, wherein the one or more processors execute the instructions to:

perform a method for demodulation of a downlink random access response (RAR) message by the UE, the method comprising:

during a random access procedure for access of the UE to a network device, receiving a downlink reference signal scrambled using an identifier (ID),

wherein the ID is a temporary UE ID provided to the UE during the random access procedure,

wherein the ID is a random access ID generated during the random access procedure, or

wherein the ID is a dedicated UE ID assigned by the network device, and the random access procedure is a contention-free random access procedure; and

demodulating the downlink RAR message using the downlink reference signal.

20. The UE of claim 19 , wherein the random access ID is a random access radio network temporary identifier (RA-RNTI) generated based on at least one of a random access preamble used by the UE in the random access procedure or time and frequency resources used by the UE in the random access procedure.

21. The UE of claim 19 wherein the ID comprises a random access identifier generated based on a synchronization signal (SS) block index of an SS block within a set of SS blocks.

22. The UE of claim 19 wherein the ID comprises a random access identifier generated based on an SS block time index associated with one or more SS blocks.

23. The UE of claim 19 , wherein the ID comprises an RA-RNTI generated as

RA-RNTI=1 +t_id+N _subframe* f _id+ SS _block+ N _ SS _Block* SS _block_time_index

wherein

RA-RNTI is a random access identifier,

t_id is an index of a subframe of a plurality of subframes, N_subframe, of a physical random access channel (PRACH),

f_id is an index in a frequency domain of the PRACH within the subframe,

SS_block indicates an SS block index of an SS block within a set of concurrently transmitted SS blocks,

SS_block_time_index is an index ranging from 0 to N_SS_Block−1, and

N_SS_Block is a maximum number of SS blocks concurrently transmitted per SS block time index.

24. A network device comprising:

a non-transitory memory storage containing instructions; and

one or more processors in communication with the non-transitory memory storage, wherein the one or more processors execute the instructions to perform a method comprising:

receiving a random access preamble from a user equipment (UE);

generating an identifier (ID);

scrambling a downlink reference signal for the UE with the ID during a random access procedure to the network device,

wherein the ID is a temporary UE ID provided to the UE during the random access procedure,

wherein the ID is a random access ID generated during the random access procedure, or

wherein the ID is a dedicated UE ID assigned by the network device, and the random access procedure is a contention-free random access procedure;

transmitting a random access message to the UE; and

transmitting the scrambled downlink reference signal for demodulation of the random access message by the UE.

25. The network device of claim 24 , wherein the downlink reference signal for the UE is associated with a Physical Downlink Shared Channel (PDSCH).

26. The network device of claim 24 , wherein the downlink reference signal for the UE is associated with a Physical Downlink Control Channel (PDCCH).

27. The network device of claim 26 , wherein the random access ID is generated based on at least one of:

the random access preamble; or

time and frequency resources used by the UE.

28. The network device of claim 24 wherein the identifier comprises a random access identifier generated based on a synchronization signal (SS) block index of an SS block within a set of SS blocks.

29. The network device of claim 24 wherein the identifier comprises a random access identifier generated based on an SS block time index associated with one or more SS blocks.

30. The network device of claim 24 , wherein the identifier comprises a random access radio network temporary identifier (RA-RNTI) generated as

RA-RNTI=1 +t_id+N _subframe* f _id+ SS _block+ N _ SS _Block* SS _block_time_index

wherein

RA-RNTI is a random access identifier,

t_id is an index of a subframe of a plurality of subframes, N_subframe, of a physical random access channel (PRACH),

f_id is an index in a frequency domain of the PRACH within the subframe,

SS_block indicates an SS block index of an SS block within a set of concurrently transmitted SS blocks,

SS_block_time_index is an index ranging from 0 to N_SS_Block−1, and

N_SS_Block is a maximum number of SS blocks concurrently transmitted per SS block time index.

31. A user equipment (UE) comprising:

a non-transitory memory storage containing instructions; and

one or more processors in communication with the non-transitory memory storage, wherein the one or more processors execute the instructions to perform a method comprising:

during a random access procedure, receiving a downlink reference signal scrambled with an identifier (ID) known to a network device with which the UE is performing the random access procedure,

wherein the ID is a temporary UE ID provided to the UE during the random access procedure,

wherein the ID is a random access ID generated during the random access procedure, or

wherein the ID is a dedicated UE ID assigned by the network device, and the random access procedure is a contention-free random access procedure;

descrambling the downlink reference signal with the same identifier known to the UE; and

demodulating, using the descrambled downlink reference signal, a random access message received from the network device during the random access procedure.

32. The UE of claim 31 , wherein the random access ID is generated based on at least one of:

a random access preamble; or

time and frequency resources used by the UE.