Communication systems using independent-sideband COFDM
OwnerAllen LeRoy Limberginventor
Life of this patent
Estimating the term…
Abstract
In independent-sideband (ISB) coded orthogonal frequency-division multiplexing (COFDM) modulation, data is transmitted twice in each COFDM symbol interval. The data is mapped both to OFDM carriers located in the lower sideband of the ISB COFDM modulation signal and to OFDM carriers located in its upper sideband. Preferably, the ordering of OFDM carriers modulated by given coded data is the same in both the lower and upper sidebands of the COFDM modulation signal. Preferably, bits of the labels in the map of QAM symbol constellations in the each sideband more likely to experience error correspond to bits of the labels in the map of QAM symbol constellations in the other sideband less likely to experience error.
Claims30
Transmitter apparatus configured for transmitting an independent-sideband coded orthogonal frequency-division modulation (ISB-COFDM) radio-frequency signal, the lower-frequency and upper-frequency sidebands of which do not mirror each other, but convey the same data in respective coded forms, said transmitter apparatus comprising:
- coding apparatus for forward-error-correction (FEC) coding digital data that is to be transmitted and arranging the resulting FEC-coded data in successive map labels for quadrature-amplitude-modulation (QAM) symbols;
- a pair of QAM mappers consisting of a first QAM mapper and a second QAM mapper, said first QAM mapper configured for generating complex coordinates of a first set of successive QAM symbols respectively responsive to said successive map labels in accordance with a first mapping pattern, and said second QAM mapper configured for generating complex coordinates of a second set of successive QAM symbols respectively responsive to said successive map labels in accordance with a second mapping pattern;
- a COFDM symbol generator for arranging successive ones of said first set of QAM symbols in first prescribed spectral order in first halves of successive COFDM symbols and arranging successive ones of said second set of QAM symbols in second prescribed spectral order in second halves of successive COFDM symbols;
- a generator of an independent-sideband coded orthogonal frequency-division modulation (ISB-COFDM) radio-frequency signal, the lower-frequency sideband of which conveys said first set of successive QAM symbols and the upper-frequency sideband of which conveys said second set of successive QAM symbols;
- and
- a linear power amplifier for amplifying said ISB-COFDM radio-frequency signal before its transmission.
Receiver apparatus for independent-sideband coded orthogonal frequency-division modulation (ISB-COFDM) radio-frequency signals the lower and upper halves of the frequency spectrum of each of which do not mirror each other, but convey the same forward-error-correction (FEC) coded data, said receiver apparatus comprising:
- means for selectively receiving a radio-frequency ISB-COFDM signal;
- means for developing a first set of QAM symbols descriptive of the discrete Fourier transform of COFDM carriers from the lower half spectrum of the selectively received ISB-COFDM radio-frequency signal;
- means for developing a second set of QAM symbols descriptive of the discrete Fourier transform of COFDM carriers from the upper half spectrum of the selectively received ISB-COFDM radio-frequency signal;
- means for serially arranging said first set of QAM symbols in each COFDM symbol in a first prescribed spectral order;
- means for serially arranging said second set of QAM symbols in each COFDM symbol in a second prescribed spectral order, such that each successive QAM symbol in said second set of QAM symbols conveys FEC-coded data related to FEC-coded data conveyed by a successive QAM symbol in said first set of QAM symbols as serially arranged in said first prescribed spectral order;
- means for demapping said first set of QAM symbols as thus serially arranged in said first prescribed spectral order to recover a first succession of QAM symbol map labels in soft-bit format and for demapping said second set of QAM symbols as thus serially arranged in said second prescribed spectral order to recover a second succession of QAM symbol map labels in soft-bit format;
- and
- a diversity combiner for combining soft bits of corresponding QAM symbol map labels in said first and second successions thereof as received as first and second input signals by said diversity combiner, thereby to reproduce soft bits of FEC-coded data as response from said diversity combiner.
Dependencies are inferred from the claim text.