PBCH content for NR unlicensed
Systems and methods of providing timing information for initial access in an unlicensed band are described. A UE monitors a new radio discovery signal (NRDS-U) window in an unlicensed band for a DRS transmission that is constrained to be transmitted within the NRDS-U window. The UE determines initial access information, including an offset that indicates when the DRS transmission occurs within the NRDS-U window, and engages in initial access dependent on the offset. The offset is from a radio frame or half radio frame boundary or the start of the NRDS-U window. The offset is indicated in three least/most significant bits an SSB index or from an sl-offset field in a MIB of the SSB. When the base station uses a DFS channel, the base station transmits a periodic signal to emulate a radar signal.
1. An apparatus, comprising:
at least one processor configured to cause a user equipment (UE) to:
perform timing synchronization with a base station (BS) for shared spectrum channel access, that includes:
monitor one or more Synchronization Signal/Physical Broadcast Channel (SS/PBCH) block transmission opportunity occasions in a periodic discovery window in the shared spectrum channel access for one or more SS/PBCH block transmissions from the base station;
wherein a number of SS/PBCH block transmission opportunity occasions for the one or more SS/PBCH block transmissions for shared spectrum is larger than a number for legacy new radio (NR) systems within a half frame; and
perform the time synchronization procedure with the base station based on the one or more SS/PBCH transmissions.
2. The apparatus of claim 1 , wherein: the SS/PBCH block having an SS/PBCH block index in which three least significant bits or three most significant bits of the SS/PBCH block index indicate an offset of the SS/PBCH block transmission from a reference position.
3. The apparatus of claim 2 , wherein the at least one processor is further configured to cause the UE to:
determine the offset from the SS/PBCH block, wherein the offset is from one of: a boundary of a radio frame in which the SS/PBCH block is to be transmitted by the base station, a boundary of a half radio frame in which the SS/PBCH block is to be transmitted by the base station, or a start of the discovery window.
4. The apparatus of claim 2 , wherein: the SS/PBCH block index comprises an additional number of bits to indicate one of a plurality of offsets within the discovery window, a total number of bits in the SS/PBCH block index being larger than six.
5. The apparatus of claim 4 , wherein: the additional number of bits are carried in physical broadcast channel (PBCH) content of the SS/PBCH block.
6. The apparatus of claim 4 , wherein: the additional number of bits are carried in a physical broadcast channel demodulation reference signal (PBCH-DMRS) of the SS/PBCH block, and 2 Z-6 additional DMRS sequences are used to indicate the offset, where Z is the total number of bits.
7. The apparatus of claim 4 , wherein: the additional number of bits are split between being carried in physical broadcast channel (PBCH) content of the SS/PBCH block and being carried in a physical broadcast channel demodulation reference signal (PBCH-DMRS) of the SS/PBCH block.
8. The apparatus of claim 2 , wherein: the SS/PBCH block comprises a master information block (MIB), and the at least one processor is further configured to cause the UE to determine the offset from a field in the MIB.
9. The apparatus of claim 8 , wherein: the offset is explicitly carried in the MIB through a specific field designated to indicate only the offset.
10. The apparatus of claim 9 , wherein: the number of SS/PBCH block transmission opportunity occasions within the discovery window is fixed, or the at least one processor is further configured to cause the UE to determine the number of SS/PBCH block transmission opportunity occasions within the discovery window by Radio Resource Control (RRC) signaling.
11. The apparatus of claim 9 , wherein: a specific SS/PBCH block transmission opportunity occasion in which the SS/PBCH block transmission occurs of a number of SS/PBCH block transmission opportunity occasions within the discovery window is indicated explicitly in the MIB through the specific field.
12. The apparatus of claim 1 , wherein the number of SS/PBCH block transmission opportunity occasions for the one or more SS/PBCH block transmissions for shared spectrum is larger than the number for legacy new radio (NR) systems within a half radio frame in order to accommodate unused SS/PBCH block transmission opportunity occasions due to base station channel access.
13. An apparatus comprising:
at least one processor configured to cause a base station (BS) to:
transmit one or more Synchronization Signal/Physical Broadcast Channel (SS/PBCH) block transmissions in a periodic discovery window in a shared spectrum channel access, wherein a number of SS/PBCH block transmission opportunity occasions for the one or more SS/PBCH block transmissions for shared spectrum is larger than a number for legacy new radio (NR) systems within a half frame; and
perform a time synchronization procedure with a user equipment (UE) based on the one or more SS/PBCH transmissions.
14. The apparatus of claim 13 , wherein the one or more SS/PBCH block transmissions having a SS/PBCH block index in which three most significant bits of the SS/PBCH block index indicate an offset of the SS/PBCH block transmission from a reference position.
15. The apparatus of claim 13 , wherein the number of SS/PBCH block transmission opportunity occasions for the one or more SS/PBCH block transmissions for shared spectrum is larger than the number for legacy new radio (NR) systems within a half radio frame in order to accommodate unused SS/PBCH block transmission opportunity occasions due to base station channel access.
16. The apparatus of claim 14 , wherein the at least one processor is further configured to cause the BS to:
determine the offset from the SS/PBCH block, wherein the offset is from one of: a boundary of a radio frame in which the SS/PBCH block is to be transmitted by the base station, a boundary of a half radio frame in which the SS/PBCH block is to be transmitted by the base station, or a start of the discovery window.
17. The apparatus of claim 14 , wherein: the SS/PBCH block index comprises an additional number of bits to indicate one of a plurality of offsets within the discovery window, a total number of bits in the SS/PBCH block index being larger than six.
18. A wireless device, comprising:
wireless communication circuitry; and
at least one processor coupled to the wireless communication circuitry and configured to cause the wireless device to
perform timing synchronization with a base station (BS) for shared spectrum channel access that includes:
monitor one or more Synchronization Signal/Physical Broadcast Channel (SS/PBCH) block transmission opportunity occasions in a periodic discovery window in the shared spectrum channel access for one or more SS/PBCH block transmissions from the base station;
wherein a number of SS/PBCH block transmission opportunity occasions for the one or more SS/PBCH block transmissions for shared spectrum is larger than a number for legacy new radio (NR) systems within a half frame; and
perform the time synchronization procedure with the base station based on the one or more SS/PBCH transmissions.
19. The wireless device of claim 18 , wherein: the one or more SS/PBCH block transmissions having a SS % PBCH block index in which three most significant bits of the SS/PBCH block index indicate an offset of the SS/PBCH block transmission from a reference position.
20. The wireless device of claim 18 , wherein the number of SS/PBCH block transmission opportunity occasions for the one or more SS/PBCH block transmissions for shared spectrum is larger than the number for legacy new radio (NR) systems within a half radio frame in order to accommodate unused SS/PBCH block transmission opportunity occasions due to base station channel access.