Digital communications system using complementary codes and amplitude modulation
First Claim
Patent Images
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
-
i, to each of said bits as a function of a predetermined transformation to generate respective complementary codes, θ
i,selecting, as a function of a first group of bits of a series of bits to be encoded, one of a plurality of amplitude patterns each defined by predetermined pattern of at least two elements,assigning the remaining groups of bits forming said series with respective ones of said phase rotations,converting the complementary codes into phase vectors,associating each of said phase vectors with a corresponding one of the elements forming the selected amplitude pattern, andmodulating carrier signals using respective ones of the resulting vectors and transmitting the modulated carrier signals to a receiver.
10 Assignments
0 Petitions
Accused Products
Abstract
The encoding/transmission of information in an OFDM system is enhanced by using complementary codes and different patterns of amplitude modulation representing respective data words. The complementary codes, more particularly, are converted into phase vectors and modulated by the selected pattern. The result is 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.
85 Citations
19 Claims
-
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,selecting, as a function of a first group of bits of a series of bits to be encoded, one of a plurality of amplitude patterns each defined by predetermined pattern of at least two elements, assigning the remaining groups of bits forming said series with respective ones of said phase rotations, converting the complementary codes into phase vectors, associating each of said phase vectors with a corresponding one of the elements forming the selected amplitude pattern, and modulating carrier signals using respective ones of the resulting vectors and transmitting the modulated carrier signals to a receiver. - View Dependent Claims (2, 3, 6, 7, 8, 9, 10)
-
i, to each of said bits as a function of a predetermined transformation to generate respective complementary codes, θ
- 4. The method of claim I wherein said step of assigning includes the steps of encoding each of said groups of bits as respective phase angles in accordance with gray scale encoding and associating the encoded phase angles with predetermined ones of said phase rotations forming said complementary codes.
-
11. A method of encoding data for transmission to a receiver, said method comprising the steps of
representing one of a number of data words by a selected one of a plurality of amplitude patterns, encoding the remaining ones of the data words into respective constellation symbols such that, based on which one of the amplitude patterns represents said one of said data words, a predetermined one of the symbols is associated with a phase constellation smaller than the phase constellation of the other ones of the 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 the complementary codes with corresponding elements forming said one of said plurality of amplitude patterns, and modulating a plurality of carrier signals with vectors representing respective ones of the amplitude modulated complementary codes and transmitting said carrier signals to a receiver.
-
18. A transmitter for transmitting encoded data to a receiver, said transmitters comprising
an encoder that selects one of a plurality of amplitude patterns to represent one of a number of data words, and encodes remaining ones of the data words into respective constellation symbols such that, based on which of the amplitude patterns represents said one of said symbols, associates a predetermined one of the symbols with a phase constellation smaller than the phase constellation of the other ones of the 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 then modulates the complementary codes with corresponding elements forming said one of said plurality of amplitude patterns, and a modulator which modulates a plurality of carrier signals with vectors representing respective ones of the amplitude modulated complementary codes and then transmits the modulated carrier signals to an intended receiver.
-
19. A receiver for receiving encoded data from a transmitter, said receiver comprising
apparatus that (a) receives a composite signal of a plurality of signals transmitted by said transmitter and regenerates individual signal vectors as a function of the received composite signal, said signal vectors having respective amplitudes and said amplitudes forming a predetermined pattern representing a particular data word, (b) selects as the pattern representing said particular data word that one of a plurality of pattern templates that provides the largest absolute correlation value when compared with the pattern of said respective amplitudes, and (c), responsive to that selection identifies which phase constellations are associated with the identified pattern, said apparatus including apparatus that applies a predetermined kernel code to said regenerated vectors to generate vector elements representing individual ones of said complementary codes, and forms, in accordance with a predetermined encoding matrix, pairs of said vector elements and associates individual ones of said pairs with respective ones of constellation symbols, in which one vector element in each of said pairs is taken as a complex conjugate so that said one vector element may be subtracted from the other vector element of the respective pair of vector elements, and then determines (a) individual ones of said constellation symbols as a function of the subtracted result obtained from the associated ones of said pairs of vector elements, and (b) 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 k, formed in part by that constellation symbol, φ
n.
-
n, not associated with any one of said pairs, as a function of the derived constellation symbols and a complementary code, θ
Specification