Reducing handover interruption time using sidelink communication
Systems, methods, apparatuses, and computer program products for reducing handover interruption time using sidelink communication are provided. For example, the handed-over (remote) user equipment may exchange uplink and downlink data with the target cell via the additional or assisting link to another relay user equipment while the remote user equipment performs the random access procedure (random access channel procedure) and may establish its own direct radio link to the target cell.
1 . An apparatus, comprising:
at least one processor; and
at least one memory including computer program code,
wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to:
send, to a target network node, a request for a relay node-aided handover of a user equipment from a first direct link with the apparatus to a second direct link with the target network node; and
receive an acknowledgement associated with the request.
2 . The apparatus of claim 1 , wherein the at least one memory and the computer program code are configured to, with the at least one processor, further cause the apparatus at least to:
receive information related to a sidelink between the user equipment and the relay node from the user equipment; and
include the information in the request.
3 . An apparatus, comprising:
at least one processor; and
at least one memory including computer program code,
wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to:
receive, from a source network node, a request for a relay node-aided handover of a user equipment from a first direct link with the source network node to a second direct link with the apparatus; and
send, to the source network node, a command to perform the relay node-aided handover.
4 . The apparatus of claim 3 , wherein the at least one memory and the computer program code are configured to, with the at least one processor, further cause the apparatus, when sending the command, at least to:
send the command in a target cell configuration message.
5 . The apparatus of claim 3 , wherein the command comprises a list of candidate relay nodes for the user equipment to choose for the relay node-aided handover.
6 . The apparatus of claim 3 , wherein the at least one memory and the computer program code are configured to, with the at least one processor, further cause the apparatus at least to:
receive an indication from the user equipment via the relay node prior to receiving a random access message from the user equipment, wherein the indication indicates that the user equipment is ready for data packet communication with the apparatus via the relay node.
7 . The apparatus of claim 3 , wherein the at least one memory and the computer program code are configured to, with the at least one processor, further cause the apparatus at least to:
receive an indication from the user equipment via the relay node prior to receiving a random access message from the user equipment, wherein the indication indicates that the user equipment is ready for data packet communication with the apparatus via the relay node, and
based on the indication, transmit a downlink data packet to the user equipment via the relay node and/or receive an uplink data packet from the user equipment via the relay node, prior to completion of the handover.
8 . The apparatus of claim 3 , wherein the at least one memory and the computer program code are configured to, with the at least one processor, further cause the apparatus at least to:
send a request to the relay node for assistance during the relay node-aided handover.