Wireless Handover Data Forwarding with Sequence-Based Discard
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Solution Overview
Problem
Existing wireless communication handover techniques face challenges such as increased network memory usage and duplicate data transmissions due to early data forwarding, which can lead to inefficient data handling and potential service disruptions.
Innovation Solution
The implementation of a mechanism that allows a target network access node to efficiently discard data packets by providing information about successfully delivered packets from the source node, using existing packet structures to minimize overhead, and optimizing data forwarding timing based on packet retransmission rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If early data forwarding is implemented during handover, then service continuity is maintained, but network memory usage increases and duplicate data transmissions occur
Solution Approach 1:
The source node forwards data packets to the target node in advance during the handover preparation phase, before the handover is executed. This preliminary action ensures that data is already available at the target node when handover occurs, maintaining service continuity while allowing the target node to discard packets that have already been successfully delivered to the UE
Solution Approach 2:
The target node receives forwarded data packets and stores them in a buffer, but actively discards packets that are identified as duplicates (packets with sequence numbers less than or equal to the last acknowledged packet). This selective discarding prevents unnecessary memory consumption while maintaining service continuity through the forwarding mechanism
2Reliability
If early data forwarding is implemented during handover, then service continuity is maintained, but duplicate data transmissions occur
Solution Approach 1:
The source node receives acknowledgment information from the UE indicating the last successfully received packet sequence number. This feedback is forwarded to the target node, which uses it to determine which packets to discard. The feedback mechanism ensures that the target node does not retransmit packets that have already been successfully delivered, eliminating duplicates while maintaining service continuity
Solution Approach 2:
The acknowledgment information containing the last successfully received packet sequence number is extracted from the handover request message and forwarded to the target node. This extracted information enables the target node to identify and exclude duplicate packets from transmission, improving data transmission efficiency while maintaining service continuity
3Productivity
If packet forwarding includes sequence identifier information, then duplicate transmissions are reduced, but packet overhead increases
Solution Approach 1:
The existing packet structure is enhanced to include additional information elements that serve multiple functions: sequence identifiers for tracking packet delivery, acknowledgment information for identifying duplicates, and handover-related data. This multi-functional approach reduces the need for separate signaling messages while maintaining data handling efficiency
Solution Approach 2:
Multiple pieces of information (sequence identifiers, acknowledgment status, handover parameters) are merged into a single forwarded data packet structure. This consolidation reduces the number of separate messages exchanged between nodes while providing all necessary information for efficient duplicate detection and transmission management
Data Source
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AI summary
Various example embodiments relate to relate to network nodes (20A; 20B), methods and computer program products configured to hand over a communication link between a cell and user equipment (10) in a wireless communication network from a source cell (40A) to a target cell (40B; 40C). According to various, but not necessarily all, embodiments of the invention there is provided a node (20A), comprising: means configured to establish a communication link between a source cell (40A) and user equipment (10); means configured to transmit a series of data packets to the user equipment (10), each data packet comprising an associated sequence identifier; means to receive an acknowledgement of successful receipt of a data packet of the series by user equipment (10), the acknowledgement comprising an indication of the successfully received data packet sequence identifier; means configured to receive an indication of an identified handover target cell (40B; 40C); means configured to request handover of the user equipment (10) to the identified handover target cell (40B; 40C); means configured to receive an acknowledgement of handover request from the identified handover target cell (40B; 40C); and means to forward data packets to be transmitted to user equipment (10) to the identified target cell (40B; 40C), the forwarded data packets comprising the indication of associated sequence identifier and the most recent successfully received data packet sequence identifier. Also provided is a node (20B), comprising: means configured to receive a request for handover of user equipment (10) from a source cell (40A) to a target cell (40B; 40C); means configured to transmit an acknowledgement of handover request to the source cell (40A); and means to receive forwarded data packets forming a series of data packets to be transmitted to user equipment (10), the forwarded data packets comprising an indication of a sequence identifier associated with each forwarded data packet and an indication of a most recent successfully received data packet sequence identifier. Arrangements recognise that one way to mitigate some of the negative effects associated with early data forwarding, for example, the increased use of network memory and the risk of duplicate transmissions, is by providing a mechanism supported by a source (20A) and target node (20B) to allow a target access node (20B) to perform efficient data discarding.