Iterative waterfiling with explicit bandwidth constraints
First Claim
1. A method of iteratively adjusting frequency bandwidths in a communications network of twisted pair modem links containing a plurality of modems, the method comprising the acts of:
- for each of said plurality of modem links, transmitting signals with an initial power spectral density mask;
measuring a signal to noise ratio for the transmitted signals;
bitloading the initial power spectral density mask for a desired data rate and a desired signal to noise ratio margin;
measuring and comparing an actual signal to noise ratio margin to the desired signal to noise ratio margin; and
adjusting the frequency bandwidth allocated in the initial power spectral density mask to minimize NEXT interference if the actual signal to noise ratio margin is not within an acceptable tolerance of the desired signal to noise ratio margin.
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Accused Products
Abstract
The present invention provides an iterative method of allocating bandwidth in a twisted pair modem communication network in order to maximize communications speed while reducing NEXT interference. The method determines frequency bandwidths that cause NEXT interference and eliminates these harmful frequencies. In further embodiments, the invention adjusts other parameters of transmission such as decreasing bitloading rates and power within problematic frequency bandwidths, while increasing power and bitloading in the remaining frequencies. The methods provide an iterative process that ensures an appropriate signal to noise ratio and maximum data transfer.
50 Citations
27 Claims
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1. A method of iteratively adjusting frequency bandwidths in a communications network of twisted pair modem links containing a plurality of modems, the method comprising the acts of:
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for each of said plurality of modem links, transmitting signals with an initial power spectral density mask; measuring a signal to noise ratio for the transmitted signals; bitloading the initial power spectral density mask for a desired data rate and a desired signal to noise ratio margin; measuring and comparing an actual signal to noise ratio margin to the desired signal to noise ratio margin; and adjusting the frequency bandwidth allocated in the initial power spectral density mask to minimize NEXT interference if the actual signal to noise ratio margin is not within an acceptable tolerance of the desired signal to noise ratio margin. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A communication system comprising:
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a plurality of modems simultaneously communicating over a plurality of twisted pair connections; and a controller for adjusting frequency bandwidths of upstream and downstream communications to reduce NEXT interference for each modem, wherein a process for adjusting the bandwidths of the upstream and downstream communications is repeated until a desired bit rate and desired signal to noise ratio margin are obtained, wherein the process for adjusting the bandwidth includes transmitting signals with an initial cower spectral density mask, measuring a signal to noise ratio for the transmitted signals, bitloading the initial power spectral density mask for a desired data rate and a desired signal to noise ratio margin, measuring and comparing an actual signal to noise ratio margin to the desired signal to noise ratio margin, and adjusting the frequency bandwidth allocated in the initial power spectral density mask if the actual signal to noise ratio margin is not within an acceptable tolerance of the desired signal to noise ratio margin. - View Dependent Claims (11, 12, 13)
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14. A method of adjusting power and frequency bandwidth in a communications network of twisted pair modem links containing a plurality of modems, the method comprising the acts of:
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for each of said plurality of modem links, transmitting signals with an initial power spectral density mask; measuring a signal to noise ratio for the transmitted signals; bitloading the initial power spectral density mask for a desired data rate and a desired signal to noise ratio margin; measuring and comparing an actual signal to noise ratio margin to the desired signal to noise ratio margin; and adjusting power and frequency bandwidth allocated in the initial power spectral density mask if the actual signal to noise ratio is not within an acceptable tolerance of the desired signal to noise ratio margin. - View Dependent Claims (15, 16, 17, 18, 19)
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20. A method of adjusting frequency bandwidths and bit transmission rates in a communications network of twisted pair modem links containing a plurality of modems to reduce NEXT interference, the method comprising the acts of:
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determining frequency bandwidths allocated in an initial power spectral density mask that produce NEXT interference; increasing bitloading and transmission rates in frequency bandwidths of the power spectral density mask that do not produce NEXT interference; and decreasing bitloading and transmission rates in frequency bandwidths of the power spectral density mask that produce NEXT interference. - View Dependent Claims (21, 22, 23, 24)
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25. A method of adjusting transmission parameters in a communications network of twisted pair modem links containing a plurality of modems to reduce NEXT interference, the method comprising the acts of:
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determining frequency bandwidths allocated in an initial power spectral density mask that produce NEXT interference; and adjusting at least one of bitloading rates, power, and frequency bandwidth parameters of the power spectral density mask, wherein NEXT interference is minimized and a desired signal to noise ratio is maintained. - View Dependent Claims (26, 27)
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Specification