Broadcast channel transmission and demodulation
A method and apparatus are disclosed for demodulating a NR-PBCH signal. The method may comprise receiving a primary SS and an SSS. The received SSS signal may be used as a reference signal to detect demodulation reference signals of the NR-PBCH. These demodulation reference signals may be interleaved with data on the NR-PBCH. In one method, the NR-PBCH DMRS are associated with an SSB index in an effort to improve randomization in the synchronization process. The NR-PBCH payload may be demodulated using the PSS and/or SSS and the DMRS. In one embodiment, the NR-PBCH DMRS may mapped to DMRS REs on a frequency first and time second mapping basis.
1. A method performed by a wireless transmit/receive unit (WTRU), the method comprising:
demodulating a payload of a physical broadcast channel (PBCH) transmission, using a demodulation reference signal (DMRS), in at least a second, in time, OFDM symbol, and a fourth, in time, OFDM symbol of a synchronization signal block (SSB), wherein the DMRS is located in same subcarriers in the second, in time, OFDM symbol and the fourth, in time, OFDM symbol and is interleaved in frequency with the payload of the PBCH;
wherein the SSB includes a primary synchronization signal (PSS) in a first, in time, OFDM symbol of the SSB and a secondary synchronization signal (SSS) in a third, in time, OFDM symbol of the SSB;
wherein the SSB spans only the first, in time, OFDM symbol, the second, in time, OFDM symbol, the third, in time, OFDM symbol and the fourth, in time, OFDM symbol;
wherein the PSS and the SSS span a same frequency spectrum and the PBCH spans a wider frequency spectrum than the PSS and the SSS.
2. The method of claim 1 , further comprising demodulating the payload of the PBCH using the PSS and/or the SSS and the DMRS.
3. The method of claim 1 , wherein the subcarriers in which the DMRS is placed are based on a cell identification (ID).
4. The method of claim 3 , wherein the DMRS is derived from a scrambling sequence based on the cell ID and an SSB index.
5. The method of claim 1 , wherein the DMRS is based on a gold sequence used by the WTRU as a reference signal (RS) for PBCH demodulation and for SSB time index detection.
6. The method of claim 4 , wherein 2 bits are used as an SSB index.
7. The method of claim 4 , wherein 3 bits are used as an SSB index.
8. The method of claim 1 , wherein the SSB spans only the first, in time, OFDM symbol, second, in time, OFDM symbol, third, in time, OFDM symbol and fourth, in time, OFDM symbol.
9. A wireless transmit/receive unit (WTRU) comprising:
a demodulator configured to use a demodulation reference signal (DMRS) to demodulate a payload of a physical broadcast channel (PBCH) transmission in at least a second, in time, OFDM symbol and a fourth, in time, OFDM symbol of a synchronization signal block (SSB), wherein the DMRS is located in same frequency locations in the second, in time, OFDM symbol and the fourth, in time, OFDM symbol and is interleaved in frequency with the payload of the PBCH;
wherein the SSB includes a primary synchronization signal (PSS) in a first, in time, OFDM symbol of the SSB and a secondary synchronization signal (SSS) in a third, in time, OFDM symbol of the SSB, wherein the DMRS is located in same frequency locations in the second, in time, OFDM symbol and the fourth, in time, OFDM symbol and is interleaved in frequency with the payload of the PBCH;
wherein the SSB spans only the first, in time, OFDM symbol, the second, in time, OFDM symbol, the third, in time, OFDM symbol and the fourth, in time, OFDM symbol;
wherein the PSS and the SSS span a same frequency spectrum and the PBCH spans a wider frequency spectrum than the PSS and the SSS.
10. The WTRU of claim 9 , wherein the demodulator is configured to demodulate the payload of the PBCH using the PSS and/or the SSS and the DMRS.
11. The WTRU of claim 9 , wherein subcarriers in which the DMRS is placed are based on a cell identification (ID).
12. The WTRU of claim 11 , wherein the DMRS is derived from a scrambling sequence based on the cell ID and an SSB index.
13. The WTRU of claim 9 , wherein the DMRS is based on a gold sequence used by the WTRU as a reference signal (RS) for PBCH demodulation and for SSB time index detection.
14. The WTRU of claim 12 , wherein 2 bits are used as an SSB index.
15. The WTRU of claim 12 , wherein 3 bits are used as an SSB index.
16. A wireless transmit/receive unit (WTRU) comprising:
a receiver configured to receive a synchronization signal block (SSB), wherein the SSB includes:
a primary synchronization signal (PSS) located in a first, in time, orthogonal frequency division multiplexing (OFDM) symbol of the SSB;
physical broadcast channel (PBCH) information located in at least a second, in time, OFDM symbol of the SSB and a fourth, in time, OFDM symbol of the SSB, wherein a demodulation reference signal (DMRS) is located in same frequency locations in the second, in time, OFDM symbol and the fourth, in time, OFDM symbol and is interleaved in frequency with a payload of the PBCH; and
a secondary synchronization signal (SSS) located in a third, in time, OFDM symbol of the SSB;
wherein the SSB spans only the first, in time, OFDM symbol, the second, in time, OFDM symbol, the third, in time, OFDM symbol and the fourth, in time, OFDM symbol;
wherein the PSS and the SSS span a same frequency spectrum and the PBCH spans a wider frequency spectrum than the PSS and the SSS.