Transport Stream Null Windows for White Space Sensing

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Solution Overview

Problem

White space devices face challenges in quieting their transmitters for sensing signals without degrading the quality of the transport stream, particularly in real-time multimedia transmission, as existing methods either disrupt the audio/visual experience or interfere with primary users in the TV band.

Innovation Solution

Incorporating a null window of time into the transport stream by modifying it to exclude essential information, allowing the transmitter to be quietly paused for sensing without impacting the quality of the multimedia experience, using techniques such as inserting NULL packets, adjusting the program clock reference, or adding a high-priority 'dummy' program to minimize disruption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the transmitter is quieted for sensing white space signals, then sensing capability is improved, but the quality of the transport stream and multimedia experience deteriorates

Engineering Contradiction:

Improvesensing capabilityVSAvoidtransport stream quality

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The transport stream is segmented into time intervals, with specific portions designated as null windows where the transmitter is quieted for sensing. This segmentation allows sensing operations to be performed without continuously disrupting the transport stream, thereby maintaining overall stream quality while enabling periodic sensing capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The transmitter operates in a periodic manner, alternating between transmission phases and sensing phases. During sensing phases, the transmitter is quieted to detect white space signals, while during transmission phases, normal multimedia content is sent. This periodic action ensures both sensing capability and transport stream quality are maintained.

Inventive Principle:

Principle #19Periodic action

2Difficulty of detecting and measuring

If the transmitter is quieted for sensing, then detection of primary users is improved, but interference with primary users increases

Engineering Contradiction:

Improvedetection of primary usersVSAvoidinterference with primary users

Core Design Contradiction:

Difficulty of detecting and measuringVSObject-generated harmful factors

Solution Approach 1:

The transmitter periodically quiets itself for sensing intervals, allowing detection of primary users in the TV band. By limiting quieting to specific periodic intervals rather than continuous operation, the system can detect primary users while minimizing the time during which the transmitter might cause interference.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system replaces continuous transmission with a combination of null packets and dummy programs that simulate transmission activity. This substitution allows the transmitter to appear active to primary users (preventing interference) while actually performing sensing operations during null windows.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If null packets are inserted into the transport stream for sensing, then transmitter quieting is enabled, but the complexity of the transport stream processing increases

Engineering Contradiction:

Improvetransmitter quieting capabilityVSAvoidtransport stream processing complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The system modifies parameters of the transport stream, such as inserting null packets at specific time intervals and adjusting program clock references. These parameter changes enable transmitter quieting for sensing while maintaining the overall structure and compatibility of the transport stream, thereby managing complexity through controlled modifications.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system introduces intermediary elements such as null packets and dummy programs that act as mediators between the sensing function and the transport stream. These intermediaries facilitate transmitter quieting for sensing while absorbing the complexity of stream modification, protecting the main multimedia content from direct impact.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9319737B2Transport layer modification to enable transmission gaps

Publication Date: 2016.04.19 QUALCOMM INC

AI summary

White space devices are operable to communicate information over white space and, more specifically, to quiet a transmitter to enable sensing signals in the white space. A method for inconspicuous quieting of a transmitter in a white space communication device modifies a transport stream for transmission by the transmitter of the white space device to provide a null window of time. The null window does not contain essential information. At least a portion of the modified transport stream is transmitted by the transmitter of the white space device. The transmitter is quieted during the null window, and white space sensing is performed during the null window.