Method and system for automatic gain control during signal acquisition
First Claim
Patent Images
1. A mobile communications device comprising:
- a receiver configured to receive a broadcast signal comprising a plurality of Orthogonal Frequency Division Multiplex (OFDM) symbols from a wireless broadcast network, and operate in either an acquisition mode or a tracking mode; and
automatic gain control circuitry configured to set a gain control value based on a first number of samples of the received broadcast signal when the receiver is operating in the acquisition mode, where the first number of samples is less than a number of samples for a one of the plurality of OFDM symbols, and on a second number of samples of the received broadcast signal when the receiver is operating in the tracking mode.
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Abstract
The disclosure is directed to a mobile communication device that includes automatic gain control (AGC) circuitry and operates in either a tracking mode or an acquisition mode. A received signal is sampled n times to calculate an energy estimate that is used to set the gain control values within the AGC circuitry. The value of n varies depending on whether the handset is operating in the acquisition mode or the tracking mode. Acquisition mode is typically considered to be the mode prior to coarse timing acquisition, also referred to as frame acquisition.
27 Citations
27 Claims
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1. A mobile communications device comprising:
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a receiver configured to receive a broadcast signal comprising a plurality of Orthogonal Frequency Division Multiplex (OFDM) symbols from a wireless broadcast network, and operate in either an acquisition mode or a tracking mode; and automatic gain control circuitry configured to set a gain control value based on a first number of samples of the received broadcast signal when the receiver is operating in the acquisition mode, where the first number of samples is less than a number of samples for a one of the plurality of OFDM symbols, and on a second number of samples of the received broadcast signal when the receiver is operating in the tracking mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for automatic gain control in a mobile communications device, comprising:
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receiving a broadcast signal comprising a plurality of Orthogonal Frequency Division Multiplex (OFDM) symbols from a wireless broadcast network; operating in either an acquisition mode or a tracking mode; and setting a gain control value based on a first number of samples of the received broadcast signal when operating in the acquisition mode, where the first number of samples is less than a number of samples for a one of the plurality of OFDM symbols, and on a second number of samples of the received broadcast signal when operating in the tracking mode. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. A wireless communications device having a receiver configured to receive a broadcast signal from a wireless broadcast network, and operate in either an acquisition mode or a tracking mode, the device comprising:
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means for estimating a received signal energy of the broadcast signal comprising a plurality of Orthogonal Frequency Division Multiplex (OFDM) symbols based on a first number of samples of the received broadcast signal when the receiver is operating in the acquisition mode and on a second number of samples of the received signal when the receiver is operating in the tracking mode, wherein the first number of samples is less than a number of samples for a one of the plurality of OFDM symbols; and means for setting a gain control value based on the estimate of the received signal energy.
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22. A mobile communications device comprising:
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a receiver configured to receive a broadcast signal from a wireless broadcast network, the broadcast signal comprising a plurality of Orthogonal Frequency Division Multiplex (OFDM) symbols, and operate in either an acquisition mode or a tracking mode; and automatic gain control circuitry configured to set a gain control value periodically at a first rate that is higher than an OFDM symbol rate when the receiver is operating in the acquisition mode and periodically at a second rate when the receiver is operating in the tracking mode. - View Dependent Claims (23)
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24. A computer-readable memory unit encoded with a computer program for automatic gain control in a mobile communications device, which upon execution cause one or more processors to:
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receive a broadcast signal comprising a plurality of Orthogonal Frequency Division Multiplex (OFDM) symbols from a wireless broadcast network; operate in either an acquisition mode or a tracking mode; and set a gain control value based on a first number of samples of the received broadcast signal when operating in the acquisition mode, where the first number of samples is less than a number of samples for a one of the plurality of OFDM symbols, and on a second number of samples of the received broadcast signal when operating in the tracking mode. - View Dependent Claims (25, 26, 27)
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Specification