Silent Symbols for Interference Characterization in Wireless Networks
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Solution Overview
Problem
Conventional communications networks face challenges in efficiently characterizing and measuring interference, particularly during short, sporadic periods, as existing methods like probes consume resources and may not accurately detect broadband noise affecting multiple subcarriers.
Innovation Solution
The introduction of 'silent symbols' within inter-frame gaps allows nodes to measure noise levels by scheduling a period with no energy transmission, enabling nodes to determine the noise floor and detect transient interference, which can then be used to adjust transmission schedules and mitigate interference effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If probes are sent frequently to identify interference events during short sporadic periods, then measurement precision improves, but resource consumption increases
Solution Approach 1:
The patent extracts the measurement function from active probe transmissions by utilizing already-present silent periods in the communication protocol. Instead of sending dedicated probe signals that consume resources, the system extracts noise floor information from existing gaps between transmissions where no signal is sent, thereby achieving interference measurement without additional resource consumption.
Solution Approach 2:
The communication protocol itself provides the measurement opportunity through its inherent silent periods between transmissions. The system uses its own operational structure (inter-frame gaps, inter-symbol gaps) to enable noise floor measurement, rather than requiring separate dedicated measurement mechanisms. This self-service approach eliminates the need for additional probe transmissions.
2Productivity
If the inter-frame gap is minimized to improve transmission efficiency, then productivity improves, but the ability to measure noise floor accurately deteriorates
Solution Approach 1:
The patent segments the measurement opportunity into multiple small time windows within the inter-frame gap structure. By identifying and utilizing specific silent periods (inter-symbol gaps, inter-chip gaps) within the overall inter-frame gap, the system can perform measurements without requiring the entire gap to be extended, thus maintaining transmission efficiency while enabling accurate noise floor measurement.
Solution Approach 2:
The system performs noise floor measurement during predetermined silent periods that are already built into the communication protocol structure. These measurement opportunities occur automatically at known time points (after each symbol, after each chip) without requiring advance scheduling or extension of gap periods, allowing continuous measurement alongside normal high-efficiency transmission.
3Measurement precision
If silent symbols are transmitted to measure noise on each subcarrier, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent makes the existing inter-frame gap structure serve multiple functions: it maintains its original role in providing transmission separation while simultaneously serving as a measurement window for noise floor estimation. This multi-functionality eliminates the need for separate dedicated measurement symbols, reducing overall system complexity while achieving accurate per-subcarrier noise measurement.
Solution Approach 2:
The system performs noise floor measurement periodically at predetermined intervals using the regular silent periods inherent in the OFDM communication structure. This periodic measurement approach, synchronized with the existing transmission frame structure, eliminates the need for complex adaptive scheduling while ensuring continuous monitoring of noise conditions across all subcarriers.
Data Source
AI summary
A method for characterizing a communication channel on a communication network includes receiving within a network node at least one silent symbol transmitted together with a packet, and determining within the network node the amount of energy received by the network node during the silent symbol. Determining the amount of energy may include comparing the amount of energy received during a first silent symbol with the amount of energy received during subsequent silent symbols. The packet transmitted with the silent symbol may include a preamble and the silent symbol may be transmitted before the preamble. The packet may include data symbols and the silent symbol may be transmitted for a duration that is shorter than the duration of one data symbol transmitted in the packet.