Wireless LAN Audio Timestamp Correction for Packet Loss

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Solution Overview

Problem

Audio communication devices in LAN environments face issues with incorrectly timestamped packets, leading to periods of silence, lost voice information, and poor communication quality due to incorrect processing of packets perceived as arriving early or late.

Innovation Solution

A wireless communications device detects and modifies the timestamp of incoming audio packets to align with the nearest frame boundary, ensuring correct processing and minimizing packet loss, with the modification only applied if the timestamp deviation is within a specified tolerance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the communications device processes packets with incorrect timestamp values strictly according to protocol specifications, then timestamp validation accuracy is improved, but audio continuity and communication quality deteriorate due to packet discarding

Engineering Contradiction:

Improvetimestamp validation accuracyVSAvoidaudio continuity

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent changes the timestamp parameter from its original incorrect value to a corrected value that aligns with frame boundaries. By detecting the deviation between the received timestamp and the expected frame boundary timestamp, the system calculates and applies a correction offset, transforming the incorrect timestamp into a valid one that allows proper packet processing without discarding audio data

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent performs preliminary timestamp validation and correction before the packet processing stage. By detecting and correcting timestamp errors in advance, the system prevents subsequent packet discarding and ensures audio continuity throughout the communication session

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If the communications device discards packets with incorrect timestamps to maintain protocol compliance, then timestamp accuracy is improved, but voice information loss increases

Engineering Contradiction:

Improvetimestamp accuracyVSAvoidvoice information loss

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

Instead of discarding packets with incorrect timestamps, the system modifies the timestamp parameter itself by calculating the deviation from the expected frame boundary and applying a correction. This preserves the audio information while ensuring the timestamp reflects the correct playback timing

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful effect of incorrect timestamps (which would normally cause packet discarding) into a beneficial correction process. By detecting the timestamp error and using it to calculate the appropriate correction, the system transforms what would be a reason for packet rejection into an opportunity for timestamp refinement and audio preservation

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Measurement precision

If the communications device plays packets with incorrect timestamps at the indicated time, then timestamp fidelity is improved, but audio quality deteriorates due to periods of silence and stuttering

Engineering Contradiction:

Improvetimestamp fidelityVSAvoidaudio quality degradation

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the timestamp parameter from its incorrect original value to a corrected value that ensures proper audio playback timing. By calculating the deviation from frame boundaries and applying the appropriate correction, the system eliminates playback timing errors that would cause silence periods and stuttering

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies preliminary correction to prevent the harmful effects of incorrect timestamps before they manifest as audio quality degradation. By detecting and correcting timestamp errors in advance of packet playback, the system prevents the occurrence of silence periods and stuttering artifacts

Inventive Principle:

Principle #9Preliminary anti-action

Data Source

PatentUS7769054B2Method of conducting a communications session using incorrect timestamps

Publication Date: 2010.08.03 SPECTRALINK CORP

AI summary

A wireless LAN can be used to support audio communication sessions between wireless communication devices and wired communication devices both configured to operate according to the Internet Protocol. Both the wired and wireless communication devices generate and transmit frames of voice information over the LAN to each other and in the process of generating these frames they place a timestamp in each frame that is used by a receiving communications device to determine when the frame should be played in relationship to all of the other frames of voice information it receives. At times these communication devices can place incorrect timestamp values in the frames of audio information which can affect the quality of the communication experience for a user. I propose to correct any incorrect timestamp values by first recognizing that a timestamp value is incorrect and then rounding the value to the nearest frame boundary.