OFDM digital communications system using complementary codes
DCFirst Claim
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1. A method of encoding data for transmission to a receiver comprising the steps ofselecting a kernel code formed from a predetermined number of bits and applying independent phase rotations, φ
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i, to each of said bits as a function of a predetermined transformation to generate respective complementary codes, θ
i,associating a predetermined number of groups of stored bits with respective ones of said phase rotations, andconverting the complementary codes into complex vectors, andmodulating carrier signals using respective ones of said vectors and transmitting the result to a receiver.
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Abstract
The encoding/transmission of information in an OFDM system is enhanced by using complementary codes. The complementary codes, more particularly, are converted into phase vectors and the resulting phase vectors are then used to modulate respective carrier signals. The modulated result is then transmitted to a receiver which decodes the received signals to recover the encoded information.
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Citations
13 Claims
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1. A method of encoding data for transmission to a receiver comprising the steps of
selecting a kernel code formed from a predetermined number of bits and applying independent phase rotations, φ -
i, to each of said bits as a function of a predetermined transformation to generate respective complementary codes, θ
i,associating a predetermined number of groups of stored bits with respective ones of said phase rotations, and converting the complementary codes into complex vectors, and modulating carrier signals using respective ones of said vectors and transmitting the result to a receiver. - View Dependent Claims (2, 3, 4, 5)
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i, to each of said bits as a function of a predetermined transformation to generate respective complementary codes, θ
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6. A method of encoding data for transmission to a receiver, said method comprising the steps of
encoding data words that are to be transmitted to said receiver into respective constellation symbols, generating a plurality of complementary codes as a function of a selected kernel code and a predetermined transformation matrix of said constellation symbols, and modulating a plurality of carrier signals with vectors representing respective ones of said complementary codes and transmitting said carrier signals to said receiver.
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12. A transmitter for transmitting encoded data to a receiver, said transmitter comprising
an encoder that encodes data words that are to be transmitted to said receiver into respective constellation symbols, a generator that generates a plurality of complementary codes as a function of a selected kernel code and a predetermined transformation matrix of said constellation symbols, and a modulator that modulates a plurality of carrier signals with vectors representing respective ones of said complementary codes and transmitting said carrier signals to said receiver.
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13. A receiver for receiving encoded data from a transmitter, said receiver comprising
apparatus that receives a composite signal of a plurality of signals transmitted by said transmitter and regenerating individual signal vectors as a function of the received composite signal, apparatus that applies a predetermined kernel code to said regenerated vectors to generate vector elements representing individual ones of said complementary codes, apparatus that forms, in accordance with a predetermined encoding matrix, pairs of said elements and associating individual ones of said pairs with respective ones of constellation symbols, in which one element in each of said pair is taken as a complex conjugate so that said one element may be subtracted from the other element of the respective pair of elements, apparatus that determines individual ones of said constellation symbols as a function of the subtracted result obtained from the associated ones of said pairs of elements, and apparatus that determines each constellation symbol, φ -
n, not associated with any one of said pairs as a function of the derived constellation symbols and a complementary code, θ
k, formed in part by that constellation symbol, φ
n.
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n, not associated with any one of said pairs as a function of the derived constellation symbols and a complementary code, θ
Specification