Methods for generating and transmitting frequency hopped signals
First Claim
1. A frequency hopping communications device for transmitting signals on a plurality of M subcarrier signals in parallel, each of said M subcarrier signals corresponding to a different one of M subcarrier signal frequencies, said M subcarrier signal frequencies being a subset of N subcarrier frequencies on which said communications device may transmit signals over time, where M<
- N, said frequency hopping communications device including;
a frequency control circuit for controlling which of the N subcarrier frequencies are used by said device for the transmission of signals;
a plurality of M separate subcarrier signals paths operating in parallel, each of the M subcarrier signal paths including a programmable signal generator coupled to said frequency control circuit, a power amplification circuit and a filter circuit, said programmable signal generator for generating a subcarrier signal having a subcarrier frequency corresponding to said subcarrier signal path to which said signal generator corresponds; and
a combining circuit for combining analog subcarrier signals corresponding to different subcarrier signal paths prior to transmission.
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Accused Products
Abstract
Methods and apparatus for generating and transmitting frequency division multiplexed signals are described. The methods are well suited for use where a device uses a small subset, M, of a larger set of N subcarrier frequencies at any given time. Each transmitted FDM signal is generated by combining a plurality of individual analog subcarrier signals whose frequency may change, e.g., be hopped as a function of time. Each generated analog subcarrier signal is amplified, e.g., power amplified, and filtered prior to being combined with other analog subcarrier signals. Filters are used to compensate for or correct signal distortions and/or reduce interference between subcarriers. Fixed frequency filters are used in an exemplary frequency hopping OFDM system. In another embodiment, the filters are programmable and change, e.g., in terms of center frequency, to match the selected subcarrier frequency as frequency hopping occurs. The bandwidth of the programmable filters may remain constant.
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Citations
23 Claims
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1. A frequency hopping communications device for transmitting signals on a plurality of M subcarrier signals in parallel, each of said M subcarrier signals corresponding to a different one of M subcarrier signal frequencies, said M subcarrier signal frequencies being a subset of N subcarrier frequencies on which said communications device may transmit signals over time, where M<
- N, said frequency hopping communications device including;
a frequency control circuit for controlling which of the N subcarrier frequencies are used by said device for the transmission of signals;
a plurality of M separate subcarrier signals paths operating in parallel, each of the M subcarrier signal paths including a programmable signal generator coupled to said frequency control circuit, a power amplification circuit and a filter circuit, said programmable signal generator for generating a subcarrier signal having a subcarrier frequency corresponding to said subcarrier signal path to which said signal generator corresponds; and
a combining circuit for combining analog subcarrier signals corresponding to different subcarrier signal paths prior to transmission. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
- N, said frequency hopping communications device including;
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14. A frequency hopping communication method for use in a communications system wherein a device can transmit information using M subcarrier signals at a time, each of the M subcarrier signals corresponding to a different subcarrier frequency, where M is less than N and where N is the total number of different subcarrier frequencies said device can use over time, the method comprising:
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i) operating M programmable signal generators to generate said M subcarrier signals;
ii) separately processing each of the M subcarrier signals to produce M processed subcarrier signals, the processing of each of said M subcarrier signals including a amplification operation and a filtering operation, said separate processing thus including M separate filtering operations; and
iii) combining the M processed subcarrier signals to generate a frequency division multiplexed transmission signal;
iv) controlling at least one of said M programmable signal generators to change the frequency of the subcarrier signal generated by said at least one programmable signal generator; and
v) repeating steps (i), (ii), and (iii). - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification