PDCP Status Report First Missing Sequence Number
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Solution Overview
Problem
In wireless communication systems, particularly in LTE networks, the existing PDCP status report mechanisms fail to accurately identify the first non-received data unit during handovers, leading to unnecessary retransmissions or dropped data due to the limitations of the LIS field, which cannot indicate a sequence number of -1, causing inefficiencies in data transfer.
Innovation Solution
The proposed solution modifies the PDCP status report format to include a 'First Missing Sequence Number' (FMS) field, which designates the sequence number of the first non-received PDCP SDU, allowing for a more accurate status report that can always be built, even when no in-sequence received PDCP SDU exists, and eliminates the need for a bit indicating the first non-received PDCP SDU in the bitmap, optimizing selective retransmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the LIS field is used to indicate the last in-sequence received PDCP SDU, then the status report can be built, but it cannot accurately identify the first non-received data unit when no in-sequence received PDCP SDU exists
Solution Approach 1:
The patent changes the parameter used for identification from LIS (Last In-Sequence) to FMS (First Missing Sequence Number). This parameter change allows the status report to accurately identify the first non-received data unit even when no in-sequence received PDCP SDU exists, as FMS can directly indicate the sequence number of the first missing unit without requiring in-sequence receipt to be established first.
2Productivity
If the LIS field is used in the status report, then the report structure is simple, but it causes unnecessary retransmissions or dropped data during handovers
Solution Approach 1:
The patent implements a feedback mechanism through the FMS field in the status report, which provides precise information about the first missing sequence number to the receiving end. This feedback enables the receiver to accurately identify which data units need retransmission, thereby improving both data transfer efficiency and reliability during handovers by avoiding unnecessary retransmissions or dropped data.
3Measurement precision
If a bit indicating the first non-received PDCP SDU is added to the bitmap, then the status report becomes more accurate, but the device complexity increases
Solution Approach 1:
The patent extracts the functionality of indicating the first non-received PDCP SDU from a separate bit in the bitmap and integrates it into the FMS field itself. By taking out this indication function and placing it in the FMS field, the patent achieves accurate status reporting without adding extra bits or increasing device complexity, as the FMS field already exists in the status report structure.
Data Source
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AI summary
Wireless communication method for transmitting a status report for a sequence of data transmitted along a wireless communication link between a wireless device and a network having a plurality of base stations, the wireless communication link having a transmitting side and a receiving side. The method comprises: on the receiving side, determining status information on data units of the sequence, indicating whether each data unit has been received or not on the receiving side; and transmitting, from the receiving side to the transmitting side of the wireless communication link, a status report containing a pointer designating a first non-received data unit in the sequence and a bitmap providing the status information for a set of data units following said first non-received data unit in the sequence.