EP0508407A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Maximum likelihood sequence estimation for rapidly varying mobile radio communication channels
Assignee: NTT Docomo Inc
•
Filing: 1992-04-08
•
Granted: —
•
Expires: 2012-04-08
Abstract
Abstract In an apparatus for equalization in an impulse response of mobile transmission which varies fast in mobile radio communication, a signal generating circuit (12-3, 12-5) outputs a signal sequence undergoing transition at a predetermined period and corresponding to each state transition and a signal sequence corresponding to the path of each state transition. An adaptive filter (12-1) receives the signal sequence corresponding to each state transition and outputs an estimated signal for each state transition. The apparatus also includes state estimating circuits for performing state estimation by using the square of an estimation error obtained by subtracting each estimated signal from a sampled signal, and a control circuit (12-4) for controlling the tap coefficient of the adaptive filter (12-1) by using the RLS algorithm in order to minimize the square of the estimation error.
Inventors
- 👤 Kazuhiko Fukawa
- 👤 Hiroshi Suzuki
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 14:24
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; H04L25/03; H04L25/03006; H04L25/03178; H04L25/03337
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
338 words
A method of equalization in an impulse response of mobile transmission which varies fast in mobile radio communication, comprising the steps of: receiving a quasi-coherent demodulated signal, and outputting a sampled signal obtained at a sampling period; receiving a code sequence undergoing transition at a predetermined period and corresponding to each state transition and a code sequence corresponding to a path of each state transition, and generating and outputting a signal sequence corresponding to each state transition and a signal sequence corresponding to the path of each state transition; receiving the signal sequence corresponding to each state transition, and outputting an estimated signal for each state transition by using an adaptive filter constituted by a transversal filter having a priori estimated coefficient vector as a tap coefficient; receiving a branch metric for each state transition, obtained by using a square of an estimation error obtained by subtracting the estimated signal for each state transition from the sampled signal, outputting a decision, the code sequence corresponding to each state transition, and the code sequence corresponding to the path of each state transition by using a Viterbi algorithm, and estimating a states; and performing control to update the priori estimated coefficient vector by adding a calculation value, as a correction term, to the prior estimated coefficient vector, the step of performing control including the step of obtaining the correction term as a calculation value which is constituted by the step of obtaining an operation value by performing an inner product operation between the signal sequence corresponding to the path of each state transition and the priori estimated coefficient vector as a basic value for the estimated signal, and calculating a priori estimation error by subtracting the operation value from the sampled signal which has undergone a predetermined delay operation, and the step of calculating a Kalman gain vector by performing an inverse matrix operation on the basis of the signal sequence corresponding to the path of each state transition, and multiplying the priori estimation error by the Kalman gain vector.
Claim 2
Independent Claim
338 words
A method of equalization in an impulse response of mobile transmission which varies fast in mobile radio communication, comprising the steps of: receiving a quasi-coherent demodulated signal, and outputting a sampled signal obtained at a sampling period; receiving a code sequence undergoing transition at a predetermined period and corresponding to each state transition and a code sequence corresponding to a path of each state transition, and generating and outputting a signal sequence corresponding to each state transition and a signal sequence corresponding to the path of each state transition; receiving the signal sequence corresponding to each state transition, and outputting an estimated signal for each state transition by using an adaptive filter constituted by a transversal filter having a priori estimated coefficient vector as a tap coefficient; receiving a branch metric for each state transition, obtained by using a square of an estimation error obtained by subtracting the estimated signal for each state transition from the sampled signal, outputting a decision, the code sequence corresponding to each state transition, and the code sequence corresponding to the path of each state transition by using a Viterbi algorithm, and estimating a states; and performing control to update the priori estimated coefficient vector by adding a calculation value, as a correction term, to the prior estimated coefficient vector, the step of performing control including the step of obtaining the correction term as a calculation value which is constituted by the step of obtaining an operation value by performing an inner product operation between the signal sequence corresponding to the path of each state transition and the priori estimated coefficient vector as a basic value for the estimated signal, and calculating a priori estimation error by subtracting the operation value from the sampled signal which has undergone a predetermined delay operation, and the step of calculating a Kalman gain vector by performing an inverse matrix operation on the basis of the signal sequence corresponding to the path of each state transition, and multiplying the priori estimation error by the Kalman gain vector.
Claim 3
Dependent Claim
64 words
A method according to claim 1, characterized in that said receiving step is sampling a quasi-coherent demodulated signal and outputting a sampled signal obtained at a sampling period for each diversity branch, and said branch metric is obtained by using a square of an estimation error obtained by subtracting an estimated signal for each state transition from a sampled signal for each diversity branch.
Claim 4
Independent Claim
326 words
An apparatus for equalization in the impulse response of mobile transmission which varies fast in mobile radio communication, comprising: receiving means (11-1 in Fig. 11) constituted by a sampling circuit for receiving a quasi-coherent demodulated signal, and outputting a sampled signal obtained at a sampling period; signal generating means (12-3, 12-5 in Fig. 12) for receiving a code sequence undergoing transition at a predetermined period and corresponding to each state transition and a code sequence corresponding to a path of each state transition, and outputting a signal sequence corresponding to each state transition and a signal sequence corresponding to the path of each state transition; adaptive filter means (12-1 in Fig. 12), constituted by a transversal filter having a tap coefficient and connected to said signal generating means, for receiving the signal sequence corresponding to each state transition, and outputting an estimated signal for each state transition; state estimating means (11-3 in Fig. 11) for receiving a branch metric for each state transition, obtained by a branch metric operation circuit using a square of an estimation error obtained by subtracting the estimated signal for each state transition from the sampled signal, outputting a decision, the code sequence corresponding to each state transition, and the code sequence corresponding to the path of each state transition by using a Viterbi algorithm; and control means (12-4 in Fig. 12) for performing an RLS algorithm for obtaining a prior estimation error by subtracting an inner product operation value, obtained by performing an inner product operation between the signal sequence corresponding to the path of each state transition and the tap coefficient, from the sampled signal which has undergone a predetermined delay operation, and for updating the tap coefficient by adding a product, obtained by multiplying the priori estimation error by a Kalman gain vector, obtained by performing a matrix operation of the signal sequence corresponding to the path of each state transition, as a correction term to the tap coefficient.
Claim 5
Independent Claim
326 words
An apparatus for equalization in the impulse response of mobile transmission which varies fast in mobile radio communication, comprising: receiving means (11-1 in Fig. 11) constituted by a sampling circuit for receiving a quasi-coherent demodulated signal, and outputting a sampled signal obtained at a sampling period; signal generating means (12-3, 12-5 in Fig. 12) for receiving a code sequence undergoing transition at a predetermined period and corresponding to each state transition and a code sequence corresponding to a path of each state transition, and outputting a signal sequence corresponding to each state transition and a signal sequence corresponding to the path of each state transition; adaptive filter means (12-1 in Fig. 12), constituted by a transversal filter having a tap coefficient and connected to said signal generating means, for receiving the signal sequence corresponding to each state transition, and outputting an estimated signal for each state transition; state estimating means (11-3 in Fig. 11) for receiving a branch metric for each state transition, obtained by a branch metric operation circuit using a square of an estimation error obtained by subtracting the estimated signal for each state transition from the sampled signal, outputting a decision, the code sequence corresponding to each state transition, and the code sequence corresponding to the path of each state transition by using a Viterbi algorithm; and control means (12-4 in Fig. 12) for performing an RLS algorithm for obtaining a prior estimation error by subtracting an inner product operation value, obtained by performing an inner product operation between the signal sequence corresponding to the path of each state transition and the tap coefficient, from the sampled signal which has undergone a predetermined delay operation, and for updating the tap coefficient by adding a product, obtained by multiplying the priori estimation error by a Kalman gain vector, obtained by performing a matrix operation of the signal sequence corresponding to the path of each state transition, as a correction term to the tap coefficient.
Claim 6
Dependent Claim
66 words
An apparatus according to claim 3, characterized in that said receiving means is constituted by a sampling circuit having a sampling period for each diversity branch, said branch metric circuit calculates and outputs a branch metric for each state transition by using a square of an estimation error obtained by subtracting an estimated signal for each state transition from a sampled signal for each diversity branch.
Claim 7
Dependent Claim
79 words
An apparatus according to claim 3, characterized in that said signal generating means outputs a symbol sequence corresponding to a state transition output from said state estimating means till a last time point of a burst, and outputs an estimated symbol sequence from a time point corresponding to a last symbol of a burst to a time point extended by an amount (K-1) times a symbol period T, provided that K represents a constraint length defining the state transition.
Claim 8
Dependent Claim
79 words
An apparatus according to claim 4, characterized in that said signal generating means outputs a symbol sequence corresponding to a state transition output from said state estimating means till a last time point of a burst, and outputs an estimated symbol sequence from a time point corresponding to a last symbol of a burst to a time point extended by an amount (K-1) times a symbol period T, provided that K represents a constraint length defining the state transition.
Claim 9
Dependent Claim
76 words
An apparatus according to claim 3, characterized in that said receiving means is a sampling circuit having a sampling period less than a symbol period, said signal generating means is a circuit for converting the code sequence into a modulation wave sequence, said adaptive filter means is a fractional tap-spacing transversal filter and said branch metric operation circuit is a circuit converting the squares of the estimation error per sampling into the branch metric per symbol.
Claim 10
Dependent Claim
80 words
An apparatus according to claim 4, characterized in that said receiving means is a sampling circuit having a sampling period less than a symbol period for each diversity branch, said signal generating means is a circuit for converting the code sequence into a modulation wave sequence, said adaptive filter means is a fractional tap-spacing transversal filter and said branch metric operation circuit is a circuit converting the squares of the estimation error per sampling into the branch metric per symbol.
Claim 11
Dependent Claim
82 words
An apparatus according to claim 7, characterized in that said signal generating means outputs a modulation wave sequence corresponding to a state transition output from said state estimating means till a last time point of a burst, and outputs an estimate modulation wave symbol sequence from a time point corresponding to a last symbol of a burst to a time point extended by an amount (K-1) times a symbol period T, provided that K represents a constraint length defining the state transition.
Claim 12
Dependent Claim
82 words
An apparatus according to claim 8, characterized in that said signal generating means outputs a modulation wave sequence corresponding to a state transition output from said state estimating means till a last time point of a burst, and outputs an estimate modulation wave symbol sequence from a time point corresponding to a last symbol of a burst to a time point extended by an amount (K-1) times a symbol period T, provided that K represents a constraint length defining the state transition.
Claim 13
Dependent Claim
37 words
An apparatus according to claim 3, characterized in that the Kalman gain vector of said control means is obtained by performing an inverse matrix operation of the signal sequence corresponding to the path of each state transition.
Claim 14
Dependent Claim
37 words
An apparatus according to claim 3, characterized in that the Kalman gain vector of said control means is obtained by performing a fixed matrix operation of the signal sequence corresponding to the path of each state transition.
Claim 15
Dependent Claim
27 words
An apparatus according to claim 3, characterized in that the tap coefficient of said transversal filter of said adaptive filter means is a priori estimated coefficient vector.
Claim 16
Dependent Claim
34 words
An apparatus according to claim 3, characterized in that the tap coefficient of said transversal filter of said adaptive filter means is a product of a priori estimated coefficient vector and a transition matrix.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.