Method and apparatus for downlink and uplink transmissions over an unlicensed spectrum
Embodiments of the present disclosure relate to methods and apparatuses for downlink and uplink transmission over an unlicensed spectrum. According to some embodiments of the disclosure, a method for wireless communications may include: determining a transport block (TB) to be transmitted on a plurality of consecutive slots; determining a set of candidate starting positions for transmitting the TB; and performing a channel access procedure for a candidate starting position from the set of candidate starting positions.
1 . A method performed by a user equipment (UE) for wireless communication, the method comprising:
receiving a downlink control information (DCI) format for scheduling a transport block (TB) on a plurality of consecutive slots;
determining the TB to be transmitted on the plurality of consecutive slots;
determining a set of candidate starting positions for transmitting the TB, wherein a number of candidate starting positions in the set of candidate starting positions is equal to a number of slots of the plurality of consecutive slots;
performing a channel access procedure for a candidate starting position from the set of candidate starting positions; and
transmitting the TB on available slots of the plurality of consecutive slots in response to the channel access procedure being successful.
2 . The method of claim 1 , wherein a first candidate starting position of the set of candidate starting positions corresponds to a first scheduled symbol of a first slot of the plurality of consecutive slots, and remaining candidate starting positions of the set of candidate starting positions correspond to first symbols of remaining slots of the plurality of consecutive slots.
3 . The method of claim 1 , wherein the TB comprises a plurality of code blocks (CBs), and each of the plurality of consecutive slots comprises an integer number of CBs of the plurality of CBs and an approximately equal number of CBs of the plurality of CBs.
4 . The method of claim 3 , wherein when a first number of slots of the plurality of consecutive slots is greater than a second number of the available slots, only the CBs of the TB mapped to a first one or more slots of the plurality of consecutive slots are transmitted; or
only the CBs of the TB mapped to a last one or more slots of the plurality of consecutive slots are transmitted.
5 . The method of claim 3 , wherein all the CBs included in a same slot are grouped as a code block group (CBG).
6 . The method of claim 5 , wherein a downlink control information (DCI) format includes a bitmap to indicate one or more CBGs to be retransmitted or transmitted, and each bit of the bitmap corresponds to a respective CBG, and wherein a number of bits of the bitmap is equal to a maximum number of the slots scheduled by the DCI format.
7 . The method of claim 3 , wherein each of the plurality of consecutive slots includes an integer number of code block groups (CBGs), and a maximum number of CBGs per TB is configured by radio resource control (RRC) signaling or is predefined.
8 . A user equipment (UE) for wireless communication, comprising:
at least one memory; and
at least one processor coupled with the at least one memory and configured to cause the UE to:
receiving a downlink control information (DCI) format for scheduling a transport block (TB) on a plurality of consecutive slots;
determine the TB to be transmitted on the plurality of consecutive slots;
determine a set of candidate starting positions for transmitting the TB, wherein a number of candidate starting positions in the set of candidate starting positions is equal to a number of slots of the plurality of consecutive slots;
perform a channel access procedure for a candidate starting position from the set of candidate starting positions; and
transmit the TB on available slots of the plurality of consecutive slots in response to the channel access procedure being successful.
9 . The UE of claim 8 , wherein a first candidate starting position of the set of candidate starting positions corresponds to a first scheduled symbol of a first slot of the plurality of consecutive slots, and remaining candidate starting positions of the set of candidate starting positions correspond to first symbols of remaining slots of the plurality of consecutive slots.
10 . The UE of claim 8 , wherein the TB comprises a plurality of code blocks (CBs), and each of the plurality of consecutive slots comprises an integer number of CBs of the plurality of CBs and an approximately equal number of CBs of the plurality of CBs.
11 . The UE of claim 10 , wherein the at least one processor is configured to cause the UE to transmit the TB on available slots of the plurality of consecutive slots in response to the channel access procedure being successful.
12 . The UE of claim 11 , wherein when a first number of slots of the plurality of consecutive slots is greater than a second number of the available slots,
only the CBs of the TB mapped to a first one or more slots of the plurality of consecutive slots are transmitted; or
only the CBs of the TB mapped to a last one or more slots of the plurality of consecutive slots are transmitted.
13 . The UE of claim 10 , wherein all the CBs included in a same slot are grouped as a code block group (CBG).
14 . The UE of claim 13 , wherein:
a downlink control information (DCI) format includes a bitmap to indicate one or more CBGs to be retransmitted or transmitted, and each bit of the bitmap corresponds to a respective CBG; and
a number of bits of the bitmap is equal to a maximum number of the slots scheduled by the DCI format.
15 . The UE of claim 10 , wherein each of the plurality of consecutive slots includes an integer number of code block groups (CBGs), and a maximum number of CBGs per TB is configured by radio resource control (RRC) signaling or is predefined.
16 . A method performed by a base station (BS), the method comprising:
transmitting a DCI format for scheduling a transport block (TB) on a plurality of consecutive slots;
determining the TB to be received on the plurality of consecutive slots;
determining a set of candidate starting positions for receiving the TB, wherein a number of candidate starting positions in the set of candidate starting positions is equal to a number of slots of the plurality of consecutive slots;
receiving the TB from a candidate starting position of the set of candidate starting positions; and
receiving the TB on available slots of the plurality of consecutive slots when a user equipment (UE) channel access procedure is successful.
17 . The method of claim 16 , wherein a first candidate starting position of the set of candidate starting positions corresponds to a first scheduled symbol of a first slot of the plurality of consecutive slots, and remaining candidate starting positions of the set of candidate starting positions correspond to first symbols of remaining slots of the plurality of consecutive slots.
18 . The method of claim 16 , wherein the TB comprises a plurality of code blocks (CBs), and each of the plurality of consecutive slots comprises an integer number of CBs of the plurality of CBs and an approximately equal number of CBs of the plurality of CBs.
19 . A base station for wireless communication, comprising:
at least one memory; and
at least one processor coupled with the at least one memory and configured to cause the base station to:
transmit a DCI format for scheduling a transport block (TB) on a plurality of consecutive slots;
determine the TB to be received on the plurality of consecutive slots;
determine a set of candidate starting positions for receiving the TB, wherein a number of candidate starting positions in the set of candidate starting positions is equal to a number of slots of the plurality of consecutive slot;
receive the TB from a candidate starting position of the set of candidate starting positions; and
receiving the TB on available slots of the plurality of consecutive slots when a user equipment (UE) channel access procedure is successful.
20 . The base station of claim 19 , wherein a first candidate starting position of the set of candidate starting positions corresponds to a first scheduled symbol of a first slot of the plurality of consecutive slots, and remaining candidate starting positions of the set of candidate starting positions correspond to first symbols of remaining slots of the plurality of consecutive slots.