Turbo-reception method and turbo-receiver

A turbo-reception method of receiving a signal from N transmitters where N is an integer equal to or greater than 2, comprising the steps of

• calculating a channel value hmn(q) and a channel matrix H from M received signals rm where M is an integer equal to or greater than 1 and where m is 1, . . . , M;
• n=1, . . . . N;
• q=0, . . . , Q−1, and Q represents a number of multipaths of each transmitted wave;
• determining a soft decision transmitted symbol b′n(k) from N a priori information λ2 [bn(k)] where k represents a discrete time;
• using the channel value hmn(q) and the soft decision transmitted symbol b′n(k) to calculate an interference component H·B′(k) upon a transmitted signal from the n-th transmitter where
• 16 H = [ H ( 0 ) … H ( Q - 1 ) 0 ⋰ ⋰ 0 H ( 0 ) … H ( Q - 1 ) ] H ( q ) = [ h 11 ⁢ ( q ) … h 1 ⁢ N ⁡ ( q ) ⋮ ⋰ ⋮ h M1 ⁡ ( q ) … h M ⁢ ⁢ N ⁡ ( q ) ] B′(k)=[b′T(k+Q−1) . . . b′T(k) . . . b′T(k−Q+1)]Tb′(k+q)=[b′1(k+q)b′2(k+q) . . . b′N(k+q)]Tq=Q−1 . . . −Q+1 q≠0b′(k)=[b′1(k) . . . −f(b′n(k)) . . . b′N (k)]T q=0
• b′(k) having an element f(b′n(k)) at an n-th position, f( ) being a function of a variable b′n(k) and satisfying that f(0)=0 and
• d{f(b′n(k))}/d{b′n(k)}≧0, and [ ]T representing a transposed matrix;
• subtracting the interference component H·B′(k) from a received matrix y(k) to determine a difference matrix y′(k) where
• y(k)=[rT(k+Q−1)rT(k+Q−2) . . . rT(k)]Tr(k)=[r1(k)r2(k) . . . rM(k)]T
• using the channel matrix H or reference signal to determine an adaptive filter coefficient wn(k) which is to be applied to a received signal corresponding to the transmitted signal from the n-th transmitter in order to eliminate residual interference components which remain in the difference matrix y′(k);
• and filtering the difference matrix y′(k) with the adaptive filter coefficient wn(k) to provide a log-likelihood ratio for the received signal which corresponds to the transmitted signal from the n-th transmitter and from which interferences are eliminated.

A turbo-reception method of receiving a signal from N transmitters where N is an integer equal to or greater than 2, comprising the steps of

• calculating a channel value hmn(q) and a channel matrix H from M received signals rm (where M is an integer equal to or greater than 1) and a known signal where m=1, . . . , M;
• n=1, . . . , N;
• q=0, . . . , Q−1, and Q represents a number of multipaths of each transmitted wave;
• determining a soft decision transmitted symbol b′n(k) from N a priori information λ2 [bn(k)] where k represents a discrete time;
• using the channel value hmn(q) and the soft decision transmitted symbol b′n (k) to calculate an interference component H·B′(k) upon a transmitted signal from an n-th transmitter where
• 18 H = [ H ( 0 ) … H ( Q - 1 ) 0 ⋰ ⋰ 0 H ( 0 ) … H ( Q - 1 ) ] H ( q ) = [ h 11 ⁢ ( q ) … h 1 ⁢ N ⁡ ( q ) ⋮ ⋰ ⋮ h M1 ⁡ ( q ) … h M ⁢ ⁢ N ⁡ ( q ) ] B′(k)=[b′T(k+Q−1) . . . b′T(k) . . . b′T(k−Q+1)]Tb′(k+q)=[b′1(k+q)b′2(k+q) . . . b′N(k+q)]Tq=Q−1 . . . −Q+1 q≠0b′(k)=[b′1(k) . . . 0 . . . b′N(k)]T q=0
• b′(k) having a zero element at an n-th position and [ ]Trepresenting a transposed matrix;
• subtracting the interference component H·B′(k) from a received matrix y(k) to determine a difference matrix y′(k) where
• y(k)=[rT(k+Q−1)rT(k+Q−2) . . . rT(k)]Tr(k)=[r1(k)r2(k) . . . rM(k)]T
• defining a covariance matrix of noise components in the received matrix y(k) as σ2 I which is determined from a variance σ2 of a Gaussian distribution and a unit matrix I, and filtering the difference matrix y′(k) with an adaptive filter coefficient wn which is determined by
• 19 h = [ ⁢ H 1 , ( Q - 1 ) · N + n H 2 , ( Q - 1 ) · N + n ⋮ H M · Q , ( Q - 1 ) · N + n ]
• to provide a log-likelihood ratio for the received signal which corresponds to the transmitted signal from the n-th transmitter and from which interferences are eliminated.

A turbo-reception method of receiving a signal from N transmitters where N is an integer equal to or greater than 2, comprising the steps of

• calculating a channel value hmn(q) and a channel matrix H from M received signals rm (where M is an integer equal to or greater than 1) and a known signal where m=1, . . . , M;
• n=1, . . . , N;
• q=0, . . . , Q−1, and Q represents a number of multi paths of each transmitted wave;
• determining a soft decision transmitted symbol b′n (k) from N a priori information λ2 [bn(k)] where k represents a discrete time;
• calculating an interference component H·B′(k) upon a transmitted signal from an n-th transmitter using the channel value hmn(q) and the soft decision transmitted symbol b′n (k) as follows:
• 20 H = [ H ( 0 ) … H ( Q - 1 ) 0 ⋰ ⋰ 0 H ( 0 ) … H ( Q - 1 ) ] H ( q ) = [ h 11 ⁢ ( q ) … h 1 ⁢ N ⁡ ( q ) ⋮ ⋰ ⋮ h M1 ⁡ ( q ) … h M ⁢ ⁢ N ⁡ ( q ) ] B′(k)=[b′T(k+Q−1) . . . b′T(k) . . . b′T(k−Q+1)]Tb′(k+q)=[b′1(k+q)b′2(k+q) . . . b′N(k+q)]Tq=Q−1 . . . −Q+1 q≠0b′(k)=[b′1(k) . . . −f(b′n(k)) . . . b′N (k)]T q=0
• where b′(k) has an element f(b′n(k)) at an n-th position, f( ) is a function of a variable b′n(k) which satisfies that of f(0)=0 and is d{f(b′n(k))}/d{ b′n(k)} ≧0 and [ ]T is a transposed matrix;
• subtracting the interference component H·B′(k) from a received matrix y(k) to define a difference matrix y′(k) where
• y(k)=[rT(k+Q−1)rT(k+Q−2) . . . rT(k)]Tr(k)=[r1(k)r2(k) . . . rM(k)]T
• defining a covariance matrix for noise components in the received matrix y(k) as σ2 I which is determined from a variance σ2 of a Gaussian distribution and unit matrix I, and filtering the difference matrix y′(k) with an adaptive filter coefficient wn(k) which is determined by
• 21 h = [ H 1 , ( Q - 1 ) · N + n H 2 , ( Q - 1 ) · N + n ⋮ H M · Q , ( Q - 1 ) · N + n ]
• to provide a log-likelihood ratio for the received signal which corresponds to the transmitted signal from the n-th transmitter and from which interferences are eliminated.

A turbo-reception method of receiving a transmitted signal from N transmitters where N is an integer equal to or greater than 2 comprising the steps of

• determining a channel value which is a transmission characteristic of a received signal from M received signals (where M is an integer equal to or greater than 1) and a known signal;.
• estimating a soft decision transmitted symbol each from N a priori information;
• dividing N transmitted signals each into L (L≦N) groups of transmitted signals including one or a plurality of transmitted signals, using a soft decision transmitted symbol and a channel matrix comprising channel values to determine L equalized signals from which interferences from other group of transmitting signals are eliminated and post-equalization channel information each corresponding to the transmission characteristic of the equalized signal for each group of transmitted signals;
• for each combination of L equalized signals and associated channel information, treating the group of equalized signals as a received signal having a channel value defined by the channel information and where there is a plurality of transmitted signals which constitute the group of equalized signals, dividing such transmitted signal into a plurality of sub-group of one or a plurality of transmitted signals, using the soft decision transmitted signal to determine an equalized signal for the subgroup of transmitted signals from which interferences from the other groups of transmitted signals are eliminated and associated post-equalization channel information, and where the group comprises a single transmitted signal, using the resulting equalized signal, the channel information and the soft decision transmitted signal to eliminate an interference of the transmitted signal itself due to multipaths;
• repeating the steps of dividing, eliminating interferences and generating post-equalization channel information until transmitted signals which constitute every equalized signal becomes a single one, thus finally determining a equalized signal for each transmitted signal from which an interference caused by multipaths of its own is eliminated or determining, for the combination of the equalized signal and associated channel information, an equalized signal from which an interference between different transmitted signals and an intersymbol interference by the transmitted signal itself is eliminated for each transmitted signal which constitutes the equalized signal.

A turbo-receiver for receiving a signal from N transmitters where N represents an integer equal to or greater than 2, comprising

• a received signal generator for forming M received signals rm (where M is an integer equal to or greater than 1) where m=1, . . . , M;
• a channel estimator to which each received signal rm and a reference signal in the form of a known signal are input for calculating a channel value hmn(q) and a channel matrix H, as defined below
• 24 H = [ H ( 0 ) ⋯ H ( Q - 1 ) 0 ⋰ ⋰ 0 H ( 0 ) ⋯ H ( Q - 1 ) ] H ( q ) = [ h 11 ⁢ ( q ) ⋯ h 1 ⁢ N ⁡ ( q ) ⋮ ⋰ ⋮ h M ⁢ ⁢ 1 ⁢ ( q ) ⋯ h MN ⁡ ( q ) ] ⁢ n = 1 , … ⁢ ⁢ N
• a received matrix generator which receives each received signal rm for generating a received matrix, as defined below
• y(k)=[rT(k+Q−1)rT(k+Q−2) . . . rT(k)]Tr(k)=[r1(k)r2(k) . . . rM(k)]T
• where k represents a discrete time, Q a number of multipaths of each transmitted wave, q=0, . . . , Q−1, and [ ]T representing a transposed matrix;
• a soft decision symbol generator receiving N a priori information for generating a soft decision transmitted symbol b′n (k);
• a replica matrix generator to which respective soft decision transmitted symbols b1′(k) to bN′(k) are input to generate an interference replica matrix B′(k) with respect to an n-th transmitted signal as follows;
• B′(k)=[b′T(k+Q−1) . . . b′T(k) . . . b′T(k−Q+1)]Tb′(k+q)=[b′1(k+q)b′2(k+q) . . . b′N(k+q)]Tq=Q−1, . . . ,−Q+1 q≠0b′(k)=[b′1(k) . . . 0 . . . b′N(k)]T q=0
• where b′(k) has a zero element at n-th position;
• a filter processor to which the channel matrix H and the interference replica matrix B′(k) are input for calculating and delivering an interference component H·B′(k) with respect to a received signal corresponding to the n-th transmitted signal;
• a difference calculator to which the interference component H·B′(k) and the received matrix y(k) are input for delivering a difference matrix y′(k)=y(k)−H·B′(k);
• a filter coefficient estimator to which the channel matrix H or a reference signal is input for determining an adaptive filter coefficient wn(k)to be applied to a received signal which corresponds to a transmitted signal from the n-th transmitter in order to eliminate residual interference components which remain in the reference matrix y′(k);
• and an adaptive filter to which the difference matrix y′(k) and the adaptive filter coefficient wn(k) are input to filter y′(k) to provide a log-likelihood ratio as an received signal which corresponds to the transmitted signal from the n-th transmitter and from which interference is eliminated and which is then fed to the n-th decoder.

A turbo-receiver for receiving a signal from N transmitters where N is an integer equal to or greater than 2, comprising

• a received signal generator for forming M received signals rm (where M is an integer equal to or greater than 1) where m=1, . . . , M;
• N decoders;
• a channel estimator to which each received signal rm and a reference signal in the form of a known signal are input to calculate a channel value hmn(q) and a channel matrix H, as defined below.
• 25 H = [ H ( 0 ) ⋯ H ( Q - 1 ) 0 ⋰ ⋰ 0 H ( 0 ) ⋯ H ( Q - 1 ) ] H ( q ) = [ h 11 ⁢ ( q ) ⋯ h 1 ⁢ N ⁡ ( q ) ⋮ ⋰ ⋮ h M ⁢ ⁢ 1 ⁢ ( q ) ⋯ h MN ⁡ ( q ) ] ⁢ n = 1 , … ⁢ ⁢ N n=1, . . . , N
• a received matrix generator to which each received signal rm is input to generate a received matrix, as defined below
• y(k)=[rT(k+Q−1)rT(k+Q−2) . . . rT(k)]Tr(k)=[r1(k)r2(k) . . . rM(k)]T
• where k represents a discrete time, Q a number of multipaths of each transmitted wave, q=0, . . . Q−1 and [ ]T a transposed matrix;
• a soft decision symbol generator to which N a priori information are input to generate soft decision transmitted symbols b′n (k) (where n=1, . . . , N);
• a replica matrix generator to which the soft decision transmitted symbols b′1 (k) to b′n (k) are input to generate an interference replica matrix B′(k) for a transmitted signal from an n-th transmitter as indicated below
• B′(k)=[b′T(k+Q−1) . . . b′T(k) . . . b′T(k−Q+1)]Tb′(k+q)=[b′1(k+q)b′2(k+q) . . . b′N(k+q)]Tq=Q−1, . . . ,−Q+1 q≠0b′(k)=[b′1(k) . . . −f(b′n(k)) . . . b′N (k)]T q=0
• where b′(k) has an element f(b′n (k)) at an n-th position, and f( ) is a function of a variable b′n (k) which satisfies that f (0)=0 and
• d{f(b′n(k))}/{ b′n (k) }≧0;
• a filter processor to which the channel matrix H and the interference replica matrix B′(k) are input to calculate and deliver an interference component H·B′(k) for a received signal which corresponds to the transmitted signal from the n-th transmitter;
• a difference calculator to which the interference component H·B′(k) and the received matrix y(k) are input to deliver a difference matrix y′(k)=y(k)−H·B′(k);
• a filter coefficient estimator to which the channel matrix H or a reference signal is input to determine an adaptive filter coefficient wn(k) for a received signal which corresponds to a transmitted signal from the n-th transmitter in order to eliminate residual interferences in the difference matrix y′(k);
• and an adaptive filter to which the difference matrix y′(k) and the adaptive filter coefficient wn(k) are input to filter y′(k) to provide a log-likelihood ratio as a received signal which corresponds to the transmitted signal from the n-th transmitter and from which interferences are eliminated and which is then fed to the n-th decoder.

A turbo-receiver for receiving a transmitted signal from N transmitters where N is an integer equal to or greater than 2, comprising

• a received signal generator for forming M received signals (where M is an integer equal to or greater than 1);
• a channel estimator to which the N received signals and a reference signals in the form of a known signal are input to estimate a channel value representing a transmission characteristic;
• a prestage equalizer to which the M received signals, the channel value and N a priori information are input for delivering, for each transmitted signal from one or more transmitters, a plurality of sets of equalized signal from which interferences by transmitted signals from other transmitters are eliminated and an associated post-equalization channel information;
• and a plurality of poststage equalizers to which the set of the equalized signal and associated channel information from the prestage equalizer, and a priori information which corresponds to the transmitted signal which constitutes the equalized signal are input to deliver a log-likelihood ratio by eliminating from the equalized signal an intersymbol interference from each transmitted signal which constitutes the equalized signal due to the multiple paths and a mutual interferences between each transmitted signal and other transmitted signals which also constituted the equalized signal.

A turbo-receiver for receiving a transmitted signal from N transmitters where N is an integer equal to or greater than 2, comprising

• a received signal generator for forming M received signals (where M is an integer equal to or greater than 1);
• a channel estimator to which the N received signals and a reference signal in the form of a known signal are input to estimate a channel value representing a transmission characteristic;
• a prestage equalizer to which the M received signals, the channel value and N a priori information are input to deliver, for each transmitted signal from one or more transmitters, a plurality of sets of an equalized signal from which interferences by transmitted signals from other transmitters are eliminated and an associated post-equalization channel information;
• and a plurality of poststage equalizers to which the sets of the equalized signal and associated channel information from the prestage equalizer, and a priori information which corresponds to a plurality of transmitted signals which constitute the equalized signal are input to deliver, for each or for a sub-group of transmitted signals among the plurality of transmitted signals which constituted the equalized signals, a plurality of sets of an equalized signal from which interference by other transmitted signals which constituted that the equalized signals are eliminated and an associated post-equalization channel information.