Systems, methods, and devices for initial access signaling in a wireless communication network
Techniques described herein may enable base stations and user equipment (UEs) to implement initial access related signaling that may vary the number of synchronization signal blocks (SSBs) transmitted by a base station to better ensure that control frame transmissions (e.g., 120 kilohertz (kHz) subcarrier spacing (SCS) transmissions) are not overly encumbered by SSBs. A base station may indicate whether a discovery burst transmission window (DBTW) is enabled or disabled, whether listen-before-talk (LBT) is enabled or disabled, and whether transmissions correspond to a licensed band, unlicensed band, or combination thereof. The base station may also indicate a number of candidate SSBs per DBTW and/or which SSBs/SSB groups are active (e.g., actually transmitted) per discovery burst (DB).
1 . A base station, comprising:
a memory; and
one or more processors configured to, when executing instructions stored in the memory, cause the base station to:
communicate, to a user equipment (UE), an indication of whether a discovery burst transmission window (DBTW) is enabled and a synchronization signal blocs (SSB) parameter, the DBTW comprising a duration of time for transmission of a plurality of synchronization signal blocks (SSBs), and the SSB parameter representing a number of the plurality of SSBs associated with quasi-co-location (QCL); and
indicate, via a number of bits of a first bitmap in a system information block (SIB), which SSBs of the plurality of SSBs are active, the number of bits being determined based on a value of the SSB parameter divided by 8; and
communicate, to the UE, active SSBs of the plurality of SSBs based on the first bitmap.
2 . The base station of claim 1 , wherein the indication is jointly signaled with the SSB parameter.
3 . The base station of claim 1 , wherein:
a one-bit indication of a subCarrierSpacingCommon information element (IE) of a master information block (MIB) is mapped to a value of the SSB parameter.
4 . The base station of claim 1 , wherein:
the indication comprises a two-bit indication, and
a combination of different values of the two-bit indication is configured or pre-defined in specification to indicate:
one of four pre-defined values for the SSB parameter, and whether the DBTW is enabled.
5 . The base station of claim 4 , wherein the four pre-defined values comprise 16, 32, 48, and 64.
6 . The base station of claim 4 , wherein:
a first bit, of the two-bit indication, comprising a subCarrierSpacingCommon IE, and
a second bit, of the two-bit indication comprising one of:
a least significant bit (LSB) of a ssb-SubcarrierOffset IE,
a most significant bit (MSB) of a controlResourceSetZero IE, or
a reserve bit of a master information block (MIB).
7 . The base station of claim 1 , wherein the SIB is used to explicitly provide the indication.
8 . The base station of claim 7 , wherein:
the SIB is used to indicate the SSB parameter,
the SSB parameter comprises one of four pre-defined values,
the four pre-defined values comprise 16, 32, 48, and 64, and
wherein the indication and the SSB parameter are configured to indicate monitoring occasions (MOs) of a common search space (CSS) to the UE for SIB reception after reception of the indication.
9 . The base station of claim 7 , wherein the one or more processors are further configured to:
communicate, to the UE, an indication of whether listen-before-talk (LBT) is enabled or disabled.
10 . The base station of claim 9 , wherein the SIB is used to implicitly indicate whether LBT is enabled or disabled based on a value of the SSB parameter and a pre-defined value of another SSB parameter representing the maximum number of supported SSBs.
11 . The base station of claim 9 , wherein the SIB is configured to indicate a licensed radio spectrum signals or unlicensed radio spectrum signals.
12 . The base station of claim 9 , wherein the indication of whether LBT is enabled or disabled for unlicensed radio spectrum signals is provided explicitly via a SubCarrierSpacingCommon field of a master information block (MIB).
13 . The base station of claim 9 , wherein whether LBT is enabled or disabled is indicated by selecting one scrambling sequence, from two pre-defined scrambling sequences, to scramble cyclic redundancy check (CRC) bits of public broadcast channel (PBCH).
14 . The base station of claim 1 , wherein the one or more processors are further configured to:
communicate information regarding which SSBs, of the plurality of SSBs, are active based on a frequency range used to communicate the active SSBs.
15 . The base station of claim 1 , wherein:
which SSBs, of the plurality of SSBs, are active, is indicated via a number of most significant bits (MSBs) of a 64-bit bitmap information element (IE) in a dedicated radio resource control (RRC) signal for the UE, and
the number of MSBs is determined as a value of the SSB parameter.
16 . The base station of claim 1 , wherein:
which SSBs, of the plurality of SSBs, are active, is indicated via a second bitmap of 8 bits.
17 . The base station of claim 1 , wherein:
when a value of the SSB parameter is less than or equal to 16,
which SSBs, of the plurality of SSBs, are active, is indicated via a concatenation of 8 bits of a second bitmap and two most significant bits (MSBs) of the first bitmap in the SIB.
18 . The base station of claim 1 , wherein:
the first bitmap has 8 bits and indicates at least one SSB group as active.
19 . A user equipment (UE), comprising:
a memory; and
one or more processors configured to, when executing instructions stored in the memory, cause the UE to:
receive, from a base station of a wireless communication network, an indication of whether a discovery burst transmission window (DBTW) is enabled for the base station and a synchronization signal blocs (SSB) parameter, the DBTW comprising a duration of time for transmission of a plurality of synchronization signal blocks (SSBs), and the SSB parameter representing a number of the plurality of SSBs associated with quasi-co-location (QCL);
receive, from the base station, at least one SSB of the plurality of SSBs in accordance with the DBTW; and
synchronize signaling, with the base station, based on the at least one SSB,
wherein a time domain position of the at least one SSB is indicated by a system information block (SIB) including a first bitmap indicating at least one SSB group and a second bitmap indicating the at least one SSB within the at least one SSB group based on the SSB parameter.
20 . The UE of claim 19 , wherein the indication, is jointly signaled with the SSB parameter.
21 . The UE of claim 19 , wherein:
a one-bit indication of a subCarrierSpacingCommon information element (IE) of a master information block (MIB) is mapped to a value of the SSB parameter.
22 . The UE of claim 20 , wherein:
the indication comprises a two-bit indication, and
a combination of different values of the two-bit indication is configured or pre-defined in specification to indicate:
one of four pre-defined values for the SSB parameter, and
whether the DBTW is enabled or disabled.
23 . The UE of claim 22 , wherein the four pre-defined values comprise 16, 32, 48, and 64.
24 . The UE of claim 23 , wherein:
a first bit, of the two-bit indication, comprising a subCarrierSpacingCommon IE, and
a second bit, of the two-bit indication comprising one of:
a least significant bit (LSB) of a ssb-SubcarrierOffset IE,
a most significant bit (MSB) of a controlResourceSetZero IE, or
a reserve bit of a master information block (MIB).
25 . The UE of claim 19 , wherein the SIB is used to explicitly provide the indication.
26 . The UE of claim 19 , wherein:
the SSB parameter comprises one of four pre-defined values of a pre-defined set of SSB parameter values,
the four pre-defined values comprise 16, 32, 48, and 64.
27 . The UE of claim 26 , wherein the smallest value in the pre-defined set of SSB parameter values is used to determine monitoring occasions (MOs) of a common search space (CSS) for SIB reception before the SSB parameter is received.
28 . The UE of claim 25 , wherein the one or more processors are further configured to:
receive, from the base station, an indication of whether listen-before-talk (LBT) is enabled or disabled.
29 . The UE of claim 28 , wherein the SIB is used to implicitly indicate whether LBT is enabled or disabled based on a value of the SSB parameter and a pre-defined value of another SSB parameter representing the maximum number of supported SSBs.