Truncated Status Report for Wireless RLC Reliability

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Solution Overview

Problem

The current Radio Link Control (RLC) protocol's status PDU format is prone to misinterpretation when the size exceeds available bandwidth, leading to premature buffer clearing and incorrect status reporting due to insufficient Medium Access Control (MAC) resources, especially in poor channel conditions.

Innovation Solution

A truncated status report is transmitted, accommodated by available radio resources, with explicit or implicit indicators to signal incompleteness, allowing subsequent reports to complete the acknowledgement information, and optionally using a modified format with a bitmap to report missing PDUs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the complete status PDU is transmitted according to the baseline format, then all missing PDUs are acknowledged, but the status PDU size exceeds available MAC bandwidth causing transmission failure

Engineering Contradiction:

Improvestatus report accuracyVSAvoidstatus PDU size

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent segments the status report into multiple parts: a first status report transmitted within available MAC resources containing critical acknowledgment information, and a second status report transmitted in subsequent opportunities containing remaining acknowledgment information. This segmentation resolves the contradiction by dividing the oversized status PDU into transmittable segments while ensuring complete acknowledgment coverage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent extracts and prioritizes critical acknowledgment information (ACK_SN and essential NACK_SNs) into the first status report that fits within MAC bandwidth constraints. Less critical or redundant acknowledgment information is deferred to subsequent status reports, enabling transmission of the most important status information within available resources.

Inventive Principle:

Principle #2Taking out (Extraction)

2Quantity of substance

If the status PDU is truncated to fit MAC resources, then transmission succeeds, but the receiver may misinterpret the status report leading to incorrect buffer clearing

Engineering Contradiction:

Improvestatus PDU sizeVSAvoidstatus report interpretation

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the receiver uses the ACK_SN value from the transmitted status report to determine which PDUs are acknowledged and which require retransmission. The ACK_SN serves as a cumulative acknowledgment pointer that provides unambiguous feedback to the transmitter about which PDUs have been successfully received, preventing misinterpretation even when the status report is truncated.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the parameter representation by using ACK_SN as a cumulative acknowledgment indicator rather than listing all individually acknowledged PDUs. This parameter change allows the status report to convey comprehensive acknowledgment information in a compact form that fits within MAC bandwidth while preventing misinterpretation through the explicit ACK_SN value.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If all NACK_SNs are included in the status report, then all missing PDUs are identified for retransmission, but the status report becomes too large for small MAC TB sizes

Engineering Contradiction:

ImprovePDU retransmission accuracyVSAvoidtransmission efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent segments the NACK_SN list into multiple transmissions. The first status report contains NACK_SNs for the most critical missing PDUs that require immediate retransmission, while less critical NACK_SNs are included in subsequent status reports. This segmentation enables efficient use of small MAC TB sizes while ensuring all missing PDUs are eventually identified for retransmission.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies partial action by including only the most essential NACK_SNs in the first status report when MAC resources are limited. This partial inclusion prioritizes critical retransmission information while deferring less critical acknowledgments to subsequent transmissions, optimizing transmission efficiency under resource constraints while maintaining eventual completeness.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS8098620B2Method for status reporting in wireless communication systems when one-time allocated resource is insufficent

Publication Date: 2012.01.17 GOOGLE TECHNOLOGY HOLDINGS LLC

AI summary

A wireless communication terminal includes a controller configured to prompt a transceiver to transmit a partial status report accommodated by a radio resource available to the terminal. The partial status report includes a sub-set of complete acknowledgement information that is associated with set of protocol data units, wherein the partial status report omits a portion of the complete acknowledgement information. The partial status reporting includes an indication that the partial status report omits the portion of the complete acknowledgement information.