Splitting and concatenating of media access control (MAC) protocol data units (PDUs) for direct transport block (TB) forwarding in relaying operations

An apparatus for wireless communication by a source node, comprising:

• a memory storing computer-executable instructions;
• and
• at least one processor coupled to the memory, the at least one processor being configured to execute the computer-executable instructions and cause the apparatus to:
• transmit, to a relay node, an indication to directly forward two or more transport blocks (TBs) to one or more destination nodes, wherein directly forwarding includes transmitting a TB of the two or more TBs to the one or more destination nodes through only a Physical (PHY) layer and a hybrid automatic repeat request (HARQ) portion of a Media Access Control (MAC) layer in a protocol stack of the relay node;
• transmit, to the relay node, control information for one or more data channels, wherein the control information comprises an identification (ID) indicating a destination node, of the one or more destination nodes, to which the one or more TBs should be directly forwarded, the control information configuring two or more DL grants;
• transmit two or more of the two or more TBs in accordance with the two or more DL grants, wherein each TB of the two or more transmitted TBs comprises one MAC sub-protocol data unit (MAC sub-PDU) corresponding to a single Internet protocol (IP) packet;
• receive, from the relay node, hybrid automatic repeat request (HARQ) acknowledgement (ACK) feedback for two or more of the two or more transmitted TBs;
• and
• transmit, to the relay node, additional control information configuring a sidelink (SL) grant that is based, at least in part, on a number of the two or more TBs for which the HARQ ACK feedback was received.

A method for wireless communication by a relay node, comprising:

• receiving, from a source node, an indication to directly forward two or more transport blocks (TBs) to one or more destination nodes, wherein directly forwarding includes transmitting a TB of the two or more TBs to the one or more destination nodes through only a Physical (PHY) layer and a hybrid automatic repeat request (HARQ) portion of a Media Access Control (MAC) layer in a protocol stack of the relay node;
• receiving, from the source node, control information for one or more data channels configuring two or more DL grants, wherein the control information comprises an identification (ID) indicating the a destination node, of the one or more destination nodes, to which the two or more TBs should be directly forwarded;
• receiving two or more of the two or more TBs in accordance with the two or more DL grants, wherein each TB of the two or more received TBs comprises one MAC sub-protocol data unit (MAC sub-PDU) corresponding to a single Internet protocol (IP) packet;
• decoding the two or more received TBs based, at least in part, on the control information;
• transmitting, to the source node, hybrid automatic repeat request (HARQ) acknowledgement (ACK) feedback for the two or more received TBs;
• receiving, from the source node, additional control information configuring a sidelink (SL) grant that is based, at least in part, on a number of the two or more received TBs at the relay node:
• concatenating the two or more received TBs in a concatenated TB;
• and
• directly forwarding the concatenated TB to the destination node based, at least in part, on the indication, the ID, and the SL grant.

A method for wireless communication by a source node, comprising:

• transmitting, to a relay node, an indication to directly forward two or more transport blocks (TBs) to one or more destination nodes, wherein directly forwarding includes transmitting a TB of the two or more TBs to the one or more destination nodes through only a Physical (PHY) layer and a hybrid automatic repeat request (HARQ) portion of a Media Access Control (MAC) layer in a protocol stack of the relay node;
• transmitting, to the relay node, control information for one or more data channels, wherein the control information comprises an identification (ID) indicating a destination node, of the one or more destination nodes, to which the one or more TBs should be directly forwarded, the control information configuring two or more DL grants;
• transmitting two or more of the two or more TBs in accordance with the two or more DL grants, wherein each TB of the two or more transmitted TBs comprises one MAC sub-protocol data unit (MAC sub-PDU) corresponding to a single Internet protocol (IP) packet;
• receiving, from the relay node, hybrid automatic repeat request (HARQ) acknowledgement (ACK) feedback for two or more of the two or more transmitted TBs;
• and
• transmitting, to the relay node, additional control information configuring a sidelink (SL) grant that is based, at least in part, on a number of the two or more TBs for which the HARQ ACK feedback was received.