OFDM digital communications system using complementary codes
AssigneeLucent Technologies Inc.
InventorsGeert Arnout Awater, Adriaan Kamerman, Anjur Sundaresan Krishnakumar, Didier J. R. van Nee
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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.
Claims13
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, .phi..sub.i, to each of said bits as a function of a predetermined transformation to generate respective complementary codes, .theta..sub.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.
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.
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.
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, .phi..sub.n, not associated with any one of said pairs as a function of the derived constellation symbols and a complementary code, .theta..sub.k, formed in part by that constellation symbol, .phi..sub.n.
Dependencies are inferred from the claim text.