Methods and apparatus for selecting between multiple carriers based on signal energy measurements
First Claim
1. A communications method for use in a wireless terminal in an OFDM communication system, the method comprising:
- receiving a first signal in a first frequency band, said first signal including a plurality of signal tones, each signal tone corresponding to a different frequency;
performing a time to frequency conversion on said received signal to generate a set of signal components corresponding to different signal tones in the first frequency band;
determining the energy of each of a plurality of different signal components which correspond to different signal tones within said first frequency band to generate a set of per signal tone energy values, each per signal tone energy value corresponding to a different frequency;
detecting, from the per tone energy value of said signal components, a signal component corresponding to a beacon signal; and
determining, based on the frequency of the signal component detected to correspond to a beacon signal, a carrier frequency corresponding to said beacon signal.
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Accused Products
Abstract
Carrier frequency selection and handoff initiation methods in wireless communications systems employing multiple carrier frequencies are described. Although the receiver is tuned to a single band, based on the relative energy of one or more beacon signal components corresponding to the currently used carrier and one or more beacon signal components corresponding to an alternative carrier, a carrier selection and a handoff determination is made. Mobile nodes can use a single RF chain with a controllable RF filter to receive and process a signal within a first selected carrier band including components from different transmitters, e.g., a first signal component identified with the first currently selected band and a second signal component identified with a second alternative band. The signal components, e.g., beacon signal components from different transmitters may be obtained from a signal which corresponds to multiple symbol transmission time periods. Separate signal energy measurements are performed on the first and second signal components. The signal component energy is compared, and a determination is made as to whether a handoff should be initiated.
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Citations
37 Claims
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1. A communications method for use in a wireless terminal in an OFDM communication system, the method comprising:
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receiving a first signal in a first frequency band, said first signal including a plurality of signal tones, each signal tone corresponding to a different frequency;
performing a time to frequency conversion on said received signal to generate a set of signal components corresponding to different signal tones in the first frequency band;
determining the energy of each of a plurality of different signal components which correspond to different signal tones within said first frequency band to generate a set of per signal tone energy values, each per signal tone energy value corresponding to a different frequency;
detecting, from the per tone energy value of said signal components, a signal component corresponding to a beacon signal; and
determining, based on the frequency of the signal component detected to correspond to a beacon signal, a carrier frequency corresponding to said beacon signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A wireless terminal for use in a communication system, the wireless terminal comprising:
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means for receiving a signal in a first period of time, said signal including a plurality of signal tones, each signal tone corresponding to a different frequency;
means for performing a time to frequency conversion on said received signal to generate a set of signal components corresponding to different signal tones in a first frequency band;
means for determining the energy of each of a plurality of different signal components which correspond to different frequencies within said first frequency band to generate a set of per signal tone energy values, each per signal tone energy value corresponding to a different frequency;
means for comparing the determined energy of each of said plurality of different signal components to a threshed energy level which is greater than the average per signal tone energy of said received signal to detect a signal component corresponding to a beacon signal; and
means for determining if a handoff should be initiated to a network attachment point which transmitted a detected beacon signal and which uses a carrier frequency to transmit user data that is different from a carrier frequency in use by said wireless terminal to communicate with a current point of network attachment. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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Specification