Spectrum Management for Point-to-Multipoint Wireless Networks

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Solution Overview

Problem

Conventional wireless broadband communications systems face limitations in bandwidth capacity and data throughput due to noise and interference in shared frequency bands, particularly in the 5 GHz unlicensed band, which reduces link availability and efficiency in spectrum use.

Innovation Solution

A method for spectrum management in point-to-multipoint wireless communications systems using a time division multiplex protocol, where noise and interference levels are measured, histogrammed, and combined estimates are used to select the best frequency channels for transmission, accounting for varying interference environments at each slave station and the master station.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If shared frequency bands (e.g., 5 GHz unlicensed band) are used to increase spectrum availability, then more channels can be deployed, but noise and interference levels increase, reducing data throughput and link availability

Engineering Contradiction:

Improvespectrum availabilityVSAvoidnoise and interference

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The system dynamically selects frequency channels based on real-time or historical interference measurements. Each slave station reports measured interference levels for multiple channels, and the master station uses this information to adaptively assign the best channels for downlink and uplink transmissions, changing channel assignments based on current spectrum conditions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

Slave stations continuously measure interference levels on available frequency channels and feed back this information to the master station. The master station uses this feedback to make informed decisions about channel allocation, adjusting spectrum usage based on the reported interference conditions from each slave station

Inventive Principle:

Principle #23Feedback

2Productivity

If conventional fixed channel allocation is used, then system complexity is low, but data throughput is limited due to inability to adapt to varying interference conditions

Engineering Contradiction:

Improvedata throughputVSAvoidspectrum management complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The system performs preliminary interference measurements and channel assessments before actual data transmissions. Slave stations measure interference levels on multiple channels in advance and report these measurements to the master station, which pre-determines the optimal channel assignments before downlink and uplink transmissions begin

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The spectrum management process is segmented into distinct phases: interference measurement phase, data collection phase, channel selection phase, and transmission phase. This segmentation allows the system to gather necessary information without interfering with data transmissions and to make channel decisions based on complete information

Inventive Principle:

Principle #1Segmentation

3Measurement precision

If interference measurements are taken during active transmission, then real-time data is obtained, but measurement accuracy is reduced due to transmission signals masking interference

Engineering Contradiction:

Improveinterference measurement accuracyVSAvoidmeasurement time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system uses periodic time division multiplexing where designated measurement timeslots are inserted into the transmission schedule. During these periodic measurement intervals, all stations remain silent to allow accurate interference measurements, while data transmissions occur during other time slots. This periodic alternation between measurement and transmission ensures both accuracy and continuous operation

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The measurement function is extracted from the transmission periods and placed into separate, dedicated measurement timeslots. This separation removes the confounding effect of transmission signals during measurement, allowing pure interference measurements to be taken without contamination from active transmissions

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS11343700B2Spectrum management for a point-to-multipoint wireless network

Publication Date: 2022.05.24 CAMBIUM NETWORKS

AI summary

In a point to multipoint wireless communications system comprising a master station and a plurality of slave stations operating according to a time division multiplex protocol, a noise and interference level is measured associated with each frequency channels at each slave station, in a predetermined timeslot of the time division multiplex protocol. A histogram is generated of the noise and interference level measurements for each slave station for each frequency channel. A noise and interference level estimate is generated for each frequency channel for each slave station as a predetermined percentile of the respective histogram, and a respective single combined noise and interference level estimate is generated for each frequency channel from the estimates. One of the frequency channels is selected for use in subsequent transmission of frames of the time division multiplex protocol on the basis of the respective single combined noise and interference level estimates.