Allocating resources for direct user equipment communication
A method and apparatus are provided for determining an active time of a user equipment to which a sidelink communication is to be sent. A sidelink resource allocation request is generated requesting allocation of a resource for transmitting this sidelink communication, the sidelink resource allocation request having an indicator indicative of the determined active time of the user equipment.
1 . An apparatus, comprising:
at least one processor; and
at least one memory including computer program code, the at least one memory and computer program code being configured to, with the at least one processor, cause the apparatus to perform at least:
operating as a transmitting user equipment (Tx UE) for sidelink communications in a mode-1 sidelink resource allocation framework;
determining, based on sidelink signaling exchanged with a receiving user equipment (Rx UE), a current active time of a discontinuous reception (DRX) cycle of the Rx UE, wherein the determining comprises deriving the current active time based on:
a sidelink DRX configuration of the Rx UE,
sidelink transmissions exchanged between the Tx UE and the Rx UE, or
a hybrid automatic repeat request (HARQ)-related activity affecting the Rx UE;
generating an extended sidelink buffer status report (SL-BSR) for requesting a dynamic mode-1 sidelink resource allocation from a network node, wherein the extended SL-BSR includes:
an active-time indicator associated with the Rx UE, and
a format indicator that explicitly specifies whether the active-time indicator represents:
a start time of the active time,
an end time of the active time, or
a duration of the active time;
encoding the active-time indicator as a time offset relative to transmission of the extended SL-BSR, wherein the time offset is expressed as a number of sidelink time slots; and
transmitting the extended SL-BSR to the network node on an uplink shared channel (UL-SCH) using a logical channel identifier (LCID) that distinguishes the extended SL-BSR from a legacy sidelink buffer status report, wherein the extended SL-BSR enables the network node to allocate a sidelink transmission resource that occurs within the determined active time of the Rx UE.
2 . The apparatus according to claim 1 , wherein said active time indicator comprises an indication of at least one of an active start time and an active end time of said at least one receiving user equipment.
3 . A method comprising:
operating as a transmitting user equipment (Tx UE) for sidelink communications in a mode-1 sidelink resource allocation framework;
determining, an based on sidelink signaling exchanged with a receiving user equipment (Rx UE), a current active time of a discontinuous reception (DRX) cycle of the Rx UE, wherein the determining comprises deriving the current active time based on:
a sidelink DRX configuration of the Rx UE,
sidelink transmissions exchanged between the Tx UE and the Rx UE, or
a hybrid automatic repeat request (HARQ)-related activity affecting the Rx UE;
generating an extended sidelink buffer status report (SL-BSR) for requesting a dynamic mode-1 sidelink resource allocation from a network node, wherein the extended SL-BSR includes:
an active-time indicator associated with the Rx UE, and
a format indicator that explicitly specifies whether the active-time indicator represents:
a start time of the active time,
an end time of the active time, or
a duration of the active time;
encoding the active-time indicator as a time offset relative to transmission of the extended SL-BSR, wherein the time offset is expressed as a number of sidelink time slots; and
transmitting the extended SL-BSR to the network node on an uplink shared channel (UL-SCH) using a logical channel identifier (LCID) that distinguishes the extended SL-BSR from a legacy sidelink buffer status report, wherein the extended SL-BSR enables the network node to allocate a sidelink transmission resource that occurs within the determined active time of the Rx UE.
4 . The method of claim 3 , wherein the active-time indicator comprises an indication of a start time of the active time of the Rx UE and an end time of the active time of the Rx UE.
5 . The method of claim 4 , wherein the active-time indicator further comprises an indication of a duration of the active time of the Rx UE, and wherein the format indicator specifies whether the active-time indicator represents the start time, the end time, or the duration.
6 . The method of claim 3 , wherein the time offset expressed as the number of sidelink time slots is quantized using an index selected from a plurality of predefined time levels, such that the index corresponds to a lowest time value that is greater than or equal to an actual start time of the active time or to a highest time value that is less than or equal to an actual end time of the active time.
7 . The method of claim 3 , wherein the extended SL-BSR is transmitted as a medium access control (MAC) control element (CE) on the uplink shared channel.
8 . The method of claim 7 , wherein the MAC CE comprises a dedicated MAC CE identified by a logical channel identifier (LCID) that is distinct from LCIDs associated with legacy sidelink buffer status reports.
9 . The method of claim 3 , further comprising:
in response to receiving an allocated mode- 1 sidelink resource that occurs outside the determined active time of the Rx UE, selecting a sidelink resource from a pool of resources for mode-2 sidelink communications and transmitting a sidelink signal to the Rx UE to trigger extension of the active time, such that the allocated mode- 1 sidelink resource occurs within the extended active time.