PDCP Status Report Bitmap Allocation for Radio Resource Efficiency
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Solution Overview
Problem
Existing methods for transmitting PDCP status reports in wireless communication systems inefficiently use radio resources, as they often transmit unnecessary information and fail to effectively convey the status of received Service Data Units (SDUs), leading to wastage and potential errors in retransmission processes.
Innovation Solution
A method for generating PDCP status reports that allocates the Bitmap field only up to the last received out-of-sequence SDU, excluding the first missing SDU, thereby reducing the size of the report and ensuring that only necessary information is transmitted, minimizing radio resource wastage and improving data integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a PDCP status report includes a Bitmap field indicating all missing SDUs up to the last received out-of-sequence SDU, then completeness of status information is improved, but radio resource efficiency deteriorates due to transmission of unnecessary information
Solution Approach 1:
The patent extracts only the necessary portion of the Bitmap field, allocating bits exclusively for missing SDUs from the first missing SDU up to (but not including) the last received out-of-sequence SDU. This extraction eliminates unnecessary bitmap entries for SDUs beyond the out-of-sequence point, thereby reducing radio resource consumption while preserving all essential status information about missing data units.
Solution Approach 2:
Instead of creating a complete Bitmap field covering all possible SDUs, the patent applies partial action by limiting the Bitmap allocation to only the relevant range of missing SDUs. This partial approach avoids the excessive transmission of status information for SDUs that are already accounted for or beyond the out-of-sequence boundary, optimizing the balance between information completeness and resource efficiency.
2Measurement precision
If the Bitmap field is allocated to cover all missing SDUs, then accuracy of retransmission control is improved, but message size increases leading to inefficient radio resource usage
Solution Approach 1:
The patent extracts the essential subset of status information by allocating Bitmap bits only for missing SDUs within the critical range (from first missing to before last received out-of-sequence). This extraction maintains accurate retransmission control for all necessary SDUs while removing redundant bitmap entries, thereby reducing the overall message size without sacrificing retransmission accuracy.
Solution Approach 2:
The patent changes the parameter of Bitmap field allocation by dynamically adjusting its size based on the actual number of missing SDUs in the relevant range. Instead of using a fixed maximum-size Bitmap, the implementation adapts the Bitmap length to match the precise needs of status reporting, optimizing the balance between retransmission control accuracy and message compactness.
3Reliability
If status reports transmit comprehensive information about all received and missing SDUs, then reliability of retransmission process is improved, but radio resource consumption increases
Solution Approach 1:
The patent extracts only the critical status information needed for reliable retransmission by limiting the Bitmap field to cover missing SDUs from the first missing position up to (but not including) the last received out-of-sequence SDU. This extraction ensures that all necessary retransmission control information is transmitted while eliminating redundant data, thereby maintaining reliability with reduced radio resource consumption.
Solution Approach 2:
The patent applies partial action by transmitting only the necessary portion of status information rather than comprehensive data about all SDUs. By focusing the Bitmap allocation exclusively on the range of missing SDUs that require retransmission attention, the system achieves reliable retransmission control without the excessive radio resource consumption that would result from reporting all possible SDU statuses.
Data Source
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AI summary
A method of transmitting PDCP (Packed Data Convergence Protocol) status reports, is performed by a mobile terminal by receiving, from an upper layer, a request for PDCP (Packed Data Convergence Protocol) re-establishment; detecting whether there are any out-of-sequence PDCP SDUs (service data units) stored; and if there is at least one out-of-sequence PDCP SDU stored, allocating a bitmap field of length in bits equal to the number of PDCP SNs from and not including the first out-of-sequence PDCP SDU up to and including a last out-of-sequence PDCP SDU.