Handover handling
AssigneeNEC Corporation
InventorJagdeep Singh Ahluwalia
Life of this patent
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Abstract
A system is proposed to provide handover in a mobile telecommunications environment, particularly applicable to 3GPP networks, which does not increase signalling overhead but minimises user data loss during handover. In the modified system, PDCP SDUs with Sequence numbers are buffered and retransmitted as necessary. At the time of handover, SDUs not received by the user device are forwarded to the target base station for forward transmission to the UE. The handover procedure is designed to minimise packet loss whilst keeping to a minimum the duplication of packet transmission over the air interface.
Claims16
A method performed by a source node which communicates with a target node, the method comprising:
- receiving uplink Packet Data Convergence Protocol (PDCP) Service Data Units (SDUs);
- transmitting, to the target node, a handover request;
- receiving, from the target node, a handover response;
- providing, to the target node, a status message, wherein the status message is configurable to include information for identifying at least a PDCP Sequence Number (SN) of a first missing uplink PDCP SDU;
- and
- forwarding, to the target node, out-of-sequence uplink PDCP SDUs after sending the status message, wherein each forwarded uplink PDCP SDU is a data unit formed by processing at least one PDCP Protocol Data Unit (PDU) received at a PDCP entity.
A source node which communicates with a target node, the source node comprising:
- a transceiver configured to:
- receive uplink Packet Data Convergence Protocol (PDCP) Service Data Units (SDUs);
- transmit, to the target node, a handover request;
- receive, from the target node, a handover response;
- provide, to the target node, a status message, wherein the status message is configurable to include information for identifying at least a PDCP Sequence Number (SN) of a first missing uplink PDCP SDU;
- and
- forward, to the target node, out-of-sequence uplink PDCP SDUs after sending the status message, wherein each forwarded uplink PDCP SDU is a data unit formed by processing at least one PDCP Protocol Data Unit (PDU) received at a PDCP entity.
Dependencies are inferred from the claim text.