Vertical roaming in wireless networks through improved wireless network cell boundary detection
First Claim
1. A computer-implemented method of wireless network cell boundary detection, comprising:
- periodically obtaining signal strength samples of wireless network signal strength received at a wireless network interface to a wireless network;
taking a Discrete Fourier Transform of the received signal strength samples; and
determining that signal strength received at the wireless network interface is decreasing in the time domain if an imaginary part of a fundamental term of the Discrete Fourier Transform of the received signal strength samples is negative and less than a Fourier-domain threshold.
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Accused Products
Abstract
A system and method for improved vertical handoff between different types of wireless network. Network allocation vector occupation and packet collision probability are used as quality of service measures, enabling vertical handoffs to be delayed until actually beneficial to quality of service. Improved wireless network cell boundary detection in vertical handoff scenarios is achieved with a Fourier-based technique in conjunction with an adaptively determined minimum operating signal strength threshold. Improved wireless network cell boundary detection enables vertical handoffs from high quality of service networks to be delayed as long as possible. Together, practical wireless network quality of service measures and improved detection of wireless network cell boundaries in vertical handoff scenarios reduce the rate of unnecessary vertical handoff resulting in higher overall quality of service experienced by a mobile computing device roaming between wireless network types.
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Citations
22 Claims
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1. A computer-implemented method of wireless network cell boundary detection, comprising:
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periodically obtaining signal strength samples of wireless network signal strength received at a wireless network interface to a wireless network;
taking a Discrete Fourier Transform of the received signal strength samples; and
determining that signal strength received at the wireless network interface is decreasing in the time domain if an imaginary part of a fundamental term of the Discrete Fourier Transform of the received signal strength samples is negative and less than a Fourier-domain threshold. - View Dependent Claims (2, 3, 5, 6, 7)
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4. (canceled)
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8. A computer-implemented method of wireless network cell boundary detection, comprising:
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periodically obtaining samples of wireless network signal strength received at a wireless network interface to a wireless network;
intensively obtaining samples of wireless network signal strength received at the wireless network interface when the samples indicate that received signal strength has dropped below a wireless network alarm threshold;
taking a Discrete Fourier Transform of the intensive received signal strength samples if an arithmetic mean of the intensive received signal strength samples are below the wireless network alarm threshold; and
determining that the signal strength received at the wireless network interface is decreasing in the time domain if an imaginary part of a fundamental term of the Discrete Fourier Transform of the intensive received signal strength samples is negative and less than a Fourier-domain threshold. - View Dependent Claims (9, 10, 11, 13, 14, 15)
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12. (canceled)
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16. A computer-implemented method of wireless network cell boundary detection, comprising:
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periodically obtaining samples of wireless network signal strength received at a wireless network interface to a wireless network;
determining a maximum received signal strength sampled during a time period; and
if the maximum received signal strength sampled during the time period is less than a minimum operating signal strength threshold for the wireless network interface, reducing the minimum operating signal strength threshold. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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Specification