System and method of robust sequence estimation in the presence of channel mismatch conditions

Claim 1

A receiving system for use with an adaptive receiver for providing an output signal x k- (L-1) 80 in response to an input signal r k 60 received from a discrete-time equivalent channel which has a linear channel filter 20 having channel filter coefficients being coupled to a transmitted information sequence x k and additive white gaussian noise 40, said receiving system comprising: a sequence estimator and a means for providing a channel estimate; said sequence estimator 70 having as inputs a received signal r k and a channel filter estimate 95 from a channel estimator 90 whose L coefficients are determined by said means for providing a channel estimate, and as output the hard decision x k- (L-1) 80 which is an estimate of the transmitted information sequence x k 10 according to the recursive relation: U.sub.k =γ.sup.-1 P.sub.k-1 v.sub.k =U.sub.k q.sub.k ##EQU12## η.sub.k =r.sub.k -q.sub.k.sup.T c.sub.k-1 P.sub.k =U.sub.k -k.sub.k v.sub.k.sup.T c.sub.k =c.sub.k-1.sup.D +k.sub.k η.sub.k x.sub.k-(L-1) =sgn(fc.sub.k) c.sub.k-1.sup.S =c.sub.k-1.sup.T S+x.sub.k g c.sub.k-1.sup.D =sgn.sub.D (c.sub.k-1.sup.S) P.sub.k =S.sup.T P.sub.k S+ε.sup.-1 gI where γ is the desired exponential weighting parameter for the sequence estimator, P k-1 is an L by L inverse correlation matrix initialized to ε -1 I, I is the L by L identity matrix, ε is the desired initialization parameter for the sequence estimator, sgn(z) denotes a binary threshold device which returns a one (1) if its parameter z is greater than or equal to zero and minus one (-1) if z is less than zero, c k is the soft-estimate vector of the transmitted information sequence x k through x k- (L-1) initialized to an arbitrary vector, sgn D (z) denotes the D-threshold device which applies the sgn-function to the left-most D bits in the vector z, f is the L-length pick-off vector given by f=[1 0 . . . 0] g is the L-length initialization vector given by g=[0 . . . 0 1] S is the L by L shift matrix given by ##EQU13## q x is the L-length channel estimate vector assigned by the channel estimator 90.

Claim 28

A method for estimating an information sequence from a signal received on a channel, said signal comprising said information sequence with a partially unknown channel filter effect, said method comprising the steps of: selectively inputting to an estimator, during a plurality of time intervals, said signal and parameters of said estimated information sequence to estimate said channel filter effect; selectively inputting to said estimator during another, different plurality of time intervals, said signal and parameters of said estimated channel filter effect to estimate said information sequence; and wherein same physical hardware, firmware and/or software of said estimator receives and estimates both said channel filter effect and said information sequence and said estimator uses same error criterion to estimate both said channel filter effect and said information sequence.

Claim 29

A method for estimating an information sequence from a signal received on a channel, said signal comprising said information sequence with a partially unknown channel filter effect, said method comprising the steps of: selectively inputting to an estimator, during a plurality of time intervals, said signal and parameters of said estimated information sequence to estimate said channel filter effect; selectively inputting to said estimator during another, different plurality of time intervals, said signal and parameters of said estimated channel filter effect to estimate said information sequence; and wherein same physical hardware, firmware and/or software of said estimator receives and estimates both said channel filter effect and said information sequence and said estimator uses same error criterion to estimate both said channel filter effect and said information sequence.