Telecommunications – Transmitter and receiver at separate stations – Distortion – noise – or other interference prevention,...
Reexamination Certificate
1998-07-23
2001-10-23
Maung, Nay (Department: 2681)
Telecommunications
Transmitter and receiver at separate stations
Distortion, noise, or other interference prevention,...
C455S067150, C342S351000
Reexamination Certificate
active
06308043
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to wireless communication link quality maintenance, and, more particularly, relates to systems and methods for predicting relative degradation and/or improvement of communication link propagation.
BACKGROUND OF THE INVENTION
Wireless, or radio, communication links are increasingly used in lieu of hardwire or other hardware links in a variety of communication modes. Because of frequency allocation crowding at lower frequencies, greater bandwidth capabilities (and therefore higher data throughputs) of higher frequencies, and advancement of technologies in higher frequency wavebands and resulting decrease in cost, gigahertz frequency wavebands are now being licensed at premium fees.
However, link quality losses related to atmospheric conditions increase significantly with signal frequency. These propagation losses are increased, for example, by the presence of water vapor, clouds, and/or rain, hail, snow, or aerosols at lower altitudes, and evolving ionospheric effects at higher altitudes.
In addition to widely used earth-based microwave links and existing satellite systems (such as the MILSTAR system), a number of new satellite systems are being proposed for implementation of ground-based communications (for example, the proposed MOTOROLA IRIDIUM, TELEDESIC, and WINSTAR systems or the like) which will operate in wavebands vulnerable to atmospheric link quality losses due to weather events. Current methods of correcting for loss of radio link quality primarily rely on correction after detecting actual loss of signal. Communication disruption is thus not prevented utilizing such current methods.
What is needed is an ability to forecast the quality of the link on a short-term basis so that the likelihood of communication link disruption or loss can be anticipated and readily mitigated (utilizing known mitigation methods such as boosting transmit power, slowing data bit rate, or switching earth station sites or satellites for example) in advance of link disruption or loss.
SUMMARY OF THE INVENTION
This invention provides apparatus and methods for forecasting the quality of a wireless communications link on a short-term basis so that the likelihood of communication link disruption or significant signal loss can be anticipated and readily mitigated in advance of such disruption or loss (and return to the status quo ante anticipated and accomplished in a timely fashion thereafter). The apparatus forecasts likely wireless communication link quality changes due to atmospheric conditions and responds to a predicted quality change in sufficient time to allow communication link adaptation, the atmospheric conditions including events likely to evolve in the vicinity of the communication link in the short-term down to and less than 15 minutes from forecasting.
The short-term forecasting apparatus of this invention for predicting quality changes of a wireless communication link includes input providing indicia of selected evolving vicinal atmospheric conditions, and processing for receiving the indicia and utilizing the indicia to provide output predicting link quality change in the short-term requiring communication link adaptation (which may be no more than a warning, but which may include suggested mitigation). The input provides data that may include measured communication link attenuation and barometric measurements, surface wind measurements, air temperature measurements, and/or atmospheric microwave power emission measurements all taken in the vicinity of the communication link.
Processing receives the data and preferably includes a preprocessing stage enhancing data features of interest. A mathematical inversion system processing stage is utilized to extract prediction of short-term link quality change from the enhanced data. An output stage receives the prediction from processing and initiates a warning or communication link remediation measures when required.
In accord with another aspect of this invention, a monolithic microwave integrated circuit radiometer receiver for use with the apparatus of this invention is provided which is inexpensive and greatly simplified. The receiver includes an antenna connected with a monolithic microwave integrated circuit transceiver. The transceiver is configured with a muted transmitter and has an intermediate frequency output coupled to a detector diode. Several stages of amplification are provided between the antenna and the diode, the amplification stages providing total amplification between the antenna and the diode selected so that, in response, the diode is preferably (though not necessarily) operated in a linear portion of its voltage out vs. power. Output voltage changes at the diode are thereby found to be directly proportional to sky emission power changes received at the antenna.
The methods of this invention include the steps of receiving indicia of selected evolving vicinal atmospheric conditions, processing the indicia to derive short-term link quality change prediction based at least in part on selected utilization of past communication link performance, and utilizing the prediction remedially.
The apparatus of this invention preferably utilizes measurements from a plurality of sensors and processes resultant data to enhance desired signal and to predict change in radio link quality. The sensors can include the radio link itself, an ensemble of site-based devices for local measurements of surface meteorology, and a site-based microwave radiometer for detecting atmospheric emissions in the vicinity of the communication link. Non-locally sensed data from satellites, radar, and other sources may supplement the system.
By subjecting data to mathematical inversion technique processing (utilizing artificial neural networks (hereinafter ANN), for example), the state of the atmosphere as it relates to propagation loss in the waveband of interest may be predicted forward in time.
The apparatus of this invention is self-monitoring as to predictive capability and self-adaptive to loss or addition of a sensor and data type, sensor drift, seasonal changes, drifts in climatology, and other environmental or system changes. This is accomplished by apparatus self-training on data as received at processing.
The apparatus and methods of this invention are site-based at the communication link (e.g., at a ground base or other site in the vicinity of the link), and provide for automatic assimilation of data from sensed signals, preprocessing (if utilized) and processing to obtain predictions of wireless communication link quality. Such sensing of atmospheric signals and processing predicts improvement as well as degradation in radio propagation links.
It is therefore an object of this invention to provide apparatus and methods for forecasting the quality of a wireless communications link on a short-term basis.
It is another object of this invention to provide apparatus and methods for forecasting the quality of a wireless communications link on a short-term basis so that the likelihood of communication link disruption or significant signal loss can be anticipated and readily mitigated in advance of such disruption or loss (and return to the status quo ante anticipated and accomplished in a timely fashion thereafter)
It is still another object of this invention to provide apparatus and methods for forecasting likely wireless communication link quality changes due to atmospheric conditions, the atmospheric conditions including events likely to evolve in the vicinity of the communication link in the short-term down to and less than 15 minutes from forecasting.
It is yet another object of this invention to provide apparatus for short-term forecasting of quality changes of a wireless communication link including input for providing indicia indicative of selected evolving vicinal atmospheric conditions, and processing for receiving the indicia and utilizing the indicia to provide output predicting link quality change in the short-term requiring communication link adaptation.
It is still another object of this inv
Solheim Fredrick S.
Yager Mark E.
Burdick Harold A.
Gary Erika A.
Maung Nay
Radiometrics Corporation
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