Buffer-status reports with multiple size fields for the same buffer
An apparatus may be configured to: determine to report an amount of data in a transmission buffer; determine respective values for a plurality of buffer-size fields that are configured to jointly indicate the amount of data in the transmission buffer, wherein the respective values are determined based on the amount of data in the transmission buffer; generate a buffer-status report, wherein the buffer-status report comprises, at least, the plurality of buffer-size fields; generate a protocol data unit, wherein the protocol data unit comprises, at least, the buffer-status report; and transmit the protocol data unit. An apparatus may be configured to: receive, from a user equipment, a protocol data unit; and determine at least one of: a lower bound for the data in the transmission buffer, or an upper bound for the data in the transmission buffer based on the plurality of buffer-size fields.
1 . A user equipment (UE) comprising:
at least one processor; and
at least one non-transitory memory storing instructions that, when executed by the at least one processor, cause the UE to perform the following operations:
determine that uplink data associated with a logical-channel group (LCG) is buffered for transmission;
determine that the UE is configured to report the buffered uplink data using multiple buffer-size fields for the same LCG within a single buffer-status report (BSR) medium access control (MAC) control element;
determine respective values for a plurality of buffer-size fields associated with the same LCG, wherein:
each buffer-size field has a predefined upper bound defined by an existing buffer-size table; and
the respective values are selected by:
indicating, for each non-first buffer-size field, a buffer-size value having a greatest upper bound that is less than or equal to a remaining unreported buffer amount, and subtracting the indicated upper bound from the remaining unreported buffer amount; and
indicating, for a first buffer-size field, a buffer-size value having a smallest upper bound that is greater than or equal to the remaining unreported buffer amount;
generate a single BSR MAC control element that includes the plurality of buffer-size fields for the same LCG;
multiplex the BSR MAC control element into a protocol data unit (PDU) without including a second BSR MAC control element for the LCG; and
transmit the protocol data unit to a radio access network node.
2 . The UE of claim 1 , wherein the plurality of buffer-size fields includes at least one 5 -bit buffer-size field and at least one 8 -bit buffer-size field associated with the same logical-channel group.
3 . The UE of claim 2 , wherein the buffer-status report MAC control element comprises a Long Short BSR format identified by a logical channel identifier distinct from a legacy Short BSR.
4 . The UE of claim 3 , wherein the plurality of buffer-size fields are included within a fixed-size MAC control element, and a number of the plurality of buffer-size fields is indicated by a MAC subheader associated with the MAC control element.
5 . The UE of claim 4 , wherein the determination that the UE is configured to report the buffered uplink data using the plurality of buffer-size fields is based on radio resource control (RRC) configuration identifying the logical-channel group as supporting additional buffer-size fields.
6 . The UE of claim 5 , wherein the respective values of the plurality of buffer-size fields are selected such that a sum of upper bounds indicated by the plurality of buffer-size fields defines an upper bound for the buffered uplink data.
7 . The UE of claim 6 , wherein the respective values of the plurality of buffer-size fields are selected such that a difference between an upper bound indicated by a first buffer-size field and upper bounds indicated by one or more additional buffer-size fields defines an upper bound for the buffered uplink data.
8 . The UE of claim 7 , wherein the generation of the buffer-status report MAC control element is performed in response to a determination that a reporting error associated with a legacy single buffer-size field exceeds a threshold.
9 . The UE of claim 8 , wherein the buffer-status report MAC control element is generated as a padding buffer-status report when unused padding bits are available in the protocol data unit.
10 . The UE of claim 9 , wherein the plurality of buffer-size fields are included only for logical-channel groups associated with extended-reality (XR) traffic.
11 . A method performed by a user equipment (UE), the method comprising:
determining that uplink data associated with a logical-channel group (LCG) is buffered for transmission;
determining that the UE is configured to report the buffered uplink data using multiple buffer-size fields for the same LCG within a single buffer-status report (BSR) medium access control (MAC) control element;
determining respective values for a plurality of buffer-size fields associated with the same LCG, wherein:
each buffer-size field has a predefined upper bound defined by an existing buffer-size table; and
the respective values are selected by:
indicating, for each non-first buffer-size field, a buffer-size value having a greatest upper bound that is less than or equal to a remaining unreported buffer amount, and subtracting the indicated upper bound from the remaining unreported buffer amount; and
indicating, for a first buffer-size field, a buffer-size value having a smallest upper bound that is greater than or equal to the remaining unreported buffer amount;
generating a single BSR MAC control element that includes the plurality of buffer-size fields for the same LCG;
multiplexing the BSR MAC control element into a protocol data unit (PDU) without including a second BSR MAC control element for the LCG; and
transmitting the protocol data unit to a radio access network node.
12 . The method of claim 11 , wherein the plurality of buffer-size fields includes at least one 5-bit buffer-size field and at least one 8-bit buffer-size field associated with the same logical-channel group.
13 . The method of claim 12 , wherein the buffer-status report MAC control element comprises a Long Short BSR format identified by a logical channel identifier distinct from a legacy Short BSR.
14 . The method of claim 13 , wherein the plurality of buffer-size fields are included within a fixed-size MAC control element, and a number of the plurality of buffer-size fields is indicated by a MAC subheader associated with the MAC control element.
15 . The method of claim 14 , wherein the determination that the UE is configured to report the buffered uplink data using the plurality of buffer-size fields is based on radio resource control (RRC) configuration identifying the logical-channel group as supporting additional buffer-size fields.
16 . The method of claim 15 , wherein the respective values of the plurality of buffer-size fields are selected such that a sum of upper bounds indicated by the plurality of buffer-size fields defines an upper bound for the buffered uplink data.
17 . The method of claim 16 , wherein the respective values of the plurality of buffer-size fields are selected such that a difference between an upper bound indicated by a first buffer-size field and upper bounds indicated by one or more additional buffer-size fields defines an upper bound for the buffered uplink data.
18 . The method of claim 17 , wherein the generation of the buffer-status report MAC control element is performed in response to a determination that a reporting error associated with a legacy single buffer-size field exceeds a threshold.
19 . The method of claim 18 , wherein the buffer-status report MAC control element is generated as a padding buffer-status report when unused padding bits are available in the protocol data unit.
20 . The method of claim 19 , wherein the plurality of buffer-size fields are included only for logical-channel groups associated with extended-reality (XR) traffic.