Scrambling of physical broadcast channel (PBCH)
A user equipment (UE) can include processing circuitry configured to decode physical broadcast channel (PBCH) information received from a base station (BS). The decoded PBCH information includes a scrambled PBCH payload and an unscrambled bit sequence. A scrambling sequence is generated based on time information signaling within the unscrambled bit sequence. The scrambled PBCH payload is de-scrambled using the scrambling sequence, to obtain master information block (MIB) information. System information block (SIB) information is decoded based on the MIB information. The decoded PBCH information includes cyclic redundancy check (CRC) information. The scrambled PBCH payload and the unscrambled bit sequence can be verified based on the CRC information. The time information signaling includes one or more bits of a system frame number (SFN).
1. An apparatus, comprising:
processing circuitry, the processing circuitry configured to cause a base station (BS) to:
generate physical broadcast channel (PBCH) payload information, the PBCH payload information including time information and master information block (MIB);
generate a scrambling sequence based on a portion of the time information;
scramble the PBCH payload by performing modulus 2 addition with the scrambling sequence to generate scrambled PBCH payload, wherein scrambling bits of the scrambling sequence are set to 0 for the PBCH payload containing the portion of the time information so that bit values of the portion of the time information are unchanged after scrambling; and
encode the scrambled PBCH payload including the portion of the time information and cyclic redundancy check (CRC) information to generate encoded PBCH information for transmission to a user equipment (UE).
2. The apparatus of claim 1 , wherein the processing circuitry is further configured to cause the BS to:
rate match the encoded PBCH information prior to transmission to the UE.
3. The apparatus of claim 1 , wherein the processing circuitry is further configured to cause the BS to:
scramble the encoded PBCH information prior to transmission to the UE using a second scrambling sequence, the second scrambling sequence based on cell-specific information associated with a cell of the BS.
4. The apparatus of claim 3 , wherein the cell-specific information is a cell ID of the cell.
5. The apparatus of claim 4 , wherein the processing circuitry is further configured to cause the BS to:
initialize the scrambling sequence using the cell ID of the cell.
6. The apparatus of claim 1 , wherein the scrambling sequence is a. length-31 Gold sequence generated using two M-sequences.
7. The apparatus of claim 1 , wherein the time information includes one or more of the following:
a system frame number (SFN); a half radio frame index; and
one or more bits of a synchronization signal block index.
8. The apparatus of claim 7 , wherein the portion of the time information for generating the scrambling sequence includes one or more bits of the SFN.
9. The apparatus of claim 7 , wherein the portion of the time information for generating the scrambling sequence includes a second and third least significant bit (LSB) of the SFN.
10. The apparatus of claim 1 , wherein the processing circuitry is further configured to cause the BS to:
interleave the scrambled PBCH payload including, the portion of the time information and the CRC information prior to encoding.
11. A user equipment (UE) comprising:
a radio; and
a processor operably coupled to the radio and configured to cause the UE to:
receive, from a base station (BS), physical broadcast channel (PBCH) payload information, the PBCH payload information including time information and master information block (MIB), wherein the PBCH payload information is scrambled using modulus 2 addition, wherein scrambling bits of a scrambling sequence are set to 0 for the PBCH payload containing a portion of the time information so that bit values of the portion of the time information are unchanged after scrambling, wherein the PBCH payload is associated with cyclic redundancy check (CRC) computed from the scrambled PBCH payload;
determine the scrambling sequence based on a portion of the time information;
de-scramble the PBCH payload with the scrambling sequence to generate de-scrambled PBCH payload; and
obtain the MIB from the de-scrambled PBCH payload.
12. The UE of claim 11 , wherein the PBCH is rate matched.
13. The UE of claim 11 , wherein de-scrambling, the PBCH is further based on a second scrambling sequence, the second scrambling sequence initialized using cell-specific information associated with a cell of the BS.
14. The UE of claim 13 , wherein the cell-specific information is a cell ID of the cell.
15. The UE of claim 14 , wherein the processor is further configured to cause the UE to:
initialize the scrambling sequence using the cell ID of the cell.
16. The UE of claim 11 , wherein the time information includes a synchronization signal block (SS Block) index, a half frame index, and a system from number (SFN).
17. The UE of claim 11 , wherein the scrambling sequence is a length-31 Gold sequence, based on two M-sequences.
18. The UE of claim 11 , wherein the PBCH payload is interleaved with the CRC.
19. An apparatus, comprising:
a processor configured to cause a user equipment (UE) to:
receive, from a base station (BS), physical broadcast channel (PBCH) payload information, the PBCH payload information including time information and master information block (MIB), wherein the PBCH payload information is scrambled using modulus 2 addition, wherein scrambling bits of a scrambling sequence are set to 0 for the PBCH payload containing a portion of the time information so that bit values of the portion of the time information are unchanged after scrambling, wherein the PBCH payload is associated with cyclic redundancy check (CRC) computed from the scrambled PBCH payload;
determine the scrambling sequence based on a portion of the time information;
de-scramble the PBCH payload with the scrambling sequence to generate de-scrambled PBCH payload; and
obtain the MIB from the de-scrambled PBCH payload.
20. The apparatus of claim 19 , wherein the PBCH is rate matched.
21. The apparatus of claim 19 , wherein de-scrambling the PBCH is further based on a second scrambling sequence, the second scrambling sequence initialized using cell-specific information associated with a cell of the BS.
22. The apparatus of claim 21 , wherein the cell-specific information is a cell ID of the cell.
23. The apparatus of claim 22 , wherein the processor is further configured to cause the UE to:
initialize the scrambling sequence using the cell ID of the cell.
24. The apparatus of claim 19 , wherein the time information includes a synchronization signal block (SS Block) index, a half frame index, and a system from number (SFN).
25. The apparatus of claim 19 , wherein the scrambling sequence is a length-31 Gold sequence, based on two M-sequences.
26. The apparatus of claim 19 , wherein the PBCH payload is interleaved with the CRC.