Receiver Storage Window Initialization for PDU Recombination
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Solution Overview
Problem
In wireless communications systems operating in Unacknowledged Mode, existing technologies face challenges in efficiently recombining Protocol Data Units (PDUs) after a receiver temporarily moves out of service range, leading to unnecessary deletion of packets and reduced recombination efficiency due to expired timers and fixed storage window mechanisms.
Innovation Solution
A method and device that initialize the storage window of a receiver by updating the sequence number variable VR(UOH) based on the sequence number of the first packet received after a timer expires, preventing unnecessary deletion of PDUs and ensuring correct recombination of SDUs upon re-establishing service range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the receiver deletes all PDUs stored in buffer after timer Timer_OSD expires, then the receiver avoids mistakenly combining PDUs from different service ranges, but the receiver cannot correctly recombine PDUs after moving back into service range
Solution Approach 1:
The patent changes the parameter initialization approach by setting VR(UOH) to the sequence number of the first received PDU instead of a fixed initial value. This dynamic parameter adjustment allows the storage window to adapt to the actual reception state, enabling correct PDU recombination after timer expiry while maintaining reliability
Solution Approach 2:
The patent performs preliminary initialization of the storage window upper bound VR(UOH) based on the first received PDU's sequence number before subsequent PDU arrivals. This preliminary action establishes the correct reference point for future PDU recombination, preventing both premature deletion and incorrect combination
2Device complexity
If the receiver initializes VR(UOH) to a fixed value, then the storage window mechanism is simple, but PDUs are unnecessarily deleted when moving out of service range
Solution Approach 1:
The patent transforms the fixed VR(UOH) initialization into a dynamic parameter that changes based on the first received PDU's sequence number. This change allows the storage window to be properly positioned, preventing unnecessary PDU deletions while maintaining manageable complexity through a single initialization step
Data Source
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AI summary
A method for initiating a storage window of a receiving end (200) in a wireless communications system, which periodically retransmits data packets in an unacknowledged mode, includes after a receiving entity of the receiving end is established, re-established, or after a timer expires (402), initiating a state variable, which is defined to be a sequence number of the highest numbered packet that has been received, according to a sequence number of a received packet (404, 406). An example of the wireless communications system is the Universal Mobile Telecommunications System (UMTS) with a multimedia broadcast/multicast service (MBMS) application.