Mapping rules between synchronization signal blocks and random access channel resources

An apparatus for wireless communications at a first node, comprising:

• a transceiver;
• a memory;
• and
• a processor communicatively coupled with the transceiver and the memory, the processor and the memory configured to:
• identify a number of actually transmitted reference signals;
• identify a number of available physical random access channel (PRACH) time-frequency resources in a time period;
• identify, a number of configured PRACH time-frequency resources per reference signal;
• determine that the available number of PRACH time-frequency resources within the time period is not an integer multiple of the product of the number of actually transmitted reference signals and the number of configured PRACH time-frequency resources per reference signal;
• and
• map the actually transmitted reference signals to the available PRACH time-frequency resources based on the identified information and determination.

An apparatus for wireless communications at a first node, comprising:

• means for identifying a number of actually transmitted reference signals;
• means for identifying a number of available physical random access channel (PRACH) time-frequency resources in a time period;
• means for identifying a number of configured PRACH time-frequency resources per reference signal;
• means for determining that the available number of PRACH time-frequency resources within the time period is not an integer multiple of the product of the number of actually transmitted reference signals and the number of configured PRACH time-frequency resources or PRACH preamble indices per reference signal;
• and
• means for mapping the actually transmitted reference signals to the available PRACH time-frequency resources and preamble indices based on the identified information and determination.

A computer-readable medium storing computer code executable by a processor of a first node for wireless communications, comprising computer executable code to:

• identify a number of actually transmitted reference signals;
• identify a number of available physical random access channel (PRACH) time-frequency resources in a time period;
• identify a number of configured PRACH time-frequency resources per reference signal;
• determine that the number of available PRACH time-frequency resources within the time period is not an integer multiple of the product of the number of actually transmitted reference signals per reference signal;
• and
• map the actually transmitted reference signals to the available PRACH time-frequency resources based on the identified information and determination.

A method of wireless communications, comprising:

• receiving, at a user equipment (UE), an indication of a number of actually transmitted synchronization signal (SS) blocks transmitted by a base station;
• receiving, at the UE, a physical random access channel (PRACH) configuration index identifying a RACH configuration period and a number of configured PRACH resources per SS-block;
• determining a time period that contains a number of PRACH resources greater than the product of the number of actually transmitted SS-blocks and the number of PRACH resources per SS-block;
• determining that a supported number of PRACH resources within the RACH time period is not an integer multiple of the product of the number of actually transmitted SS-blocks and the number of configured PRACH resources per SS-block;
• and
• mapping the number of actually transmitted SS-blocks an integer number of times within the PRACH resources of the time period, wherein a remaining number of PRACH resources are not assigned to an SS-block.

A user equipment (UE), comprising:

• a transceiver;
• a memory;
• and
• a processor communicatively coupled with the transceiver and the memory, the processor and the memory configured to:
• receive, at the UE, an indication of a number of actually transmitted synchronization signal (SS) blocks transmitted by a base station;
• receive, at the UE, a physical random access channel (PRACH) configuration index identifying a RACH configuration period and a number of configured PRACH resources per SS-block;
• determine a time period that contains a number of PRACH resources greater than the product of the number of actually transmitted SS-blocks and the number of PRACH resources per SS-block;
• determine that a supported number of PRACH resources within the time period is not an integer multiple of the product of the number of actually transmitted SS-blocks and the number of configured PRACH resources per SS-block;
• and
• map the number of actually transmitted SS-blocks an integer number of times within the PRACH resources of the time period, wherein a remaining number of PRACH resources are not assigned to an SS-block.

A user equipment (UE), comprising:

• means for receiving, at the UE, an indication of a number of actually transmitted synchronization signal (SS) blocks transmitted by a base station;
• means for receiving, at the UE, a physical random access channel (PRACH) configuration index identifying a RACH configuration period and a number of configured PRACH resources per SS-block;
• means for determining a time period that contains a number of PRACH resources greater than the product of the number of actually transmitted SS-blocks and the number of PRACH resources per SS-block
• means for determining that a supported number of PRACH resources within the time period is not an integer multiple of the product of the number of actually transmitted SS-blocks and the number of configured PRACH resources per SS-block;
• and
• means for mapping the number of actually transmitted SS-blocks an integer number of times within the PRACH resources of the time period, wherein a remaining number of PRACH resources are not assigned to an SS-block.

A computer-readable medium storing computer code executable by a processor for wireless communications, comprising computer executable code to:

• receive, at a user equipment (UE), an indication of a number of actually transmitted synchronization signal (SS) blocks transmitted by a base station;
• receive, at the UE, a physical random access channel (PRACH) configuration index identifying a RACH configuration period and a number of configured PRACH resources per SS-block;
• determine a time period that contains a number of PRACH resources greater than the product of the number of actually transmitted SS-blocks and the number of PRACH resources per SS-block;
• determine that a supported number of PRACH resources within the time period is not an integer multiple of the product of the number of actually transmitted SS-blocks and the number of configured PRACH resources per SS-block;
• and
• map the number of actually transmitted SS-blocks an integer number of times within the PRACH resources of the time period, wherein a remaining number of PRACH resources are not assigned to an SS-block.

A method of wireless communications, comprising:

• transmitting, from a base station, a number of synchronization signal (SS) blocks and an indication of a number of transmitted SS-blocks;
• transmitting, from the base station, a physical random access channel (PRACH) configuration index defining a RACH configuration period;
• and
• designating a mapping rule between the number of transmitted SS-blocks to PRACH resources or PRACH preamble indices within the RACH configuration period, wherein the mapping rule assigns different SS-blocks to PRACH resources or PRACH preamble indices for different groups of user equipment.

A base station for wireless communications, comprising:

• a transceiver;
• a memory;
• and
• a processor communicatively coupled with the transceiver and the memory, the processor and the memory configured to:
• transmit, from a base station, a number of synchronization signal (SS) blocks and an indication of a number of transmitted SS-blocks;
• transmit, from the base station, a physical random access channel (PRACH) configuration index defining a RACH configuration period;
• and
• designate a mapping rule between the number of transmitted SS-blocks to PRACH resources or PRACH preamble indices within the RACH configuration period, wherein the mapping rule assigns different SS-blocks to PRACH resources or PRACH preamble indices for different groups of user equipment.

A base station for wireless communications, comprising:

• means for transmitting, from a base station, a number of synchronization signal (SS) blocks and an indication of a number of transmitted SS-blocks;
• means for transmitting, from the base station, a physical random access channel (PRACH) configuration index defining a RACH configuration period;
• and
• means for designating a mapping rule between the number of transmitted SS-blocks to PRACH resources or PRACH preamble indices within the RACH configuration period, wherein the mapping rule assigns different SS-blocks to PRACH resources or PRACH preamble indices for different groups of user equipment.

A computer-readable medium storing computer code executable by a processor for wireless communications, comprising computer executable code for:

• transmitting, from a base station, a number of synchronization signal (SS) blocks and an indication of a number of transmitted SS-blocks;
• transmitting, from the base station, a physical random access channel (PRACH) configuration index defining a RACH configuration period;
• and
• designating a mapping rule between the number of transmitted SS-blocks to PRACH resources or PRACH preamble indices within the RACH configuration period, wherein the mapping rule assigns different SS-blocks to PRACH resources or PRACH preamble indices for different groups of user equipment.