EP0239153A2 — Adaptive blind equalization method and device

Claim 1

Independent Claim 174 words

Adaptive blind equalization method for reception of electrical signals codified into symbols and transmitted on a transmission channel of unknown characteristics variable in time which introduce an intersymbol interference, said reception taking place by means of a reception device comprising a filter with adaptable parameters at the output of which there are signal samples, a decision element which assigns to each signal sample a symbol, and a control device which on the basis of a pilot vector of the received signal, of the signal samples and of the decided symbols regulates the adaptable parameters of the filter until there is reached an optimal configuration which gives the least intersymbol interference characterized in that said optimal configuration of the parameters (c n+1 ) ) of the filter (1) which gives the least intersymbol interference is obtained by minimizing a cost function by means of self-decided symbols (a ) of the decision element (4) without knowledge n of the symbols actually transmitted and of the signal samples (z ) available at the filter output (1). n

Claim 2

Dependent Claim 174 words

Adaptive blind equalization method for reception of electrical signals codified into symbols and transmitted on a transmission channel of unknown characteristics variable in time which introduce an intersymbol interference, said reception taking place by means of a reception device comprising a filter with adaptable parameters at the output of which there are signal samples, a decision element which assigns to each signal sample a symbol, and a control device which on the basis of a pilot vector of the received signal, of the signal samples and of the decided symbols regulates the adaptable parameters of the filter until there is reached an optimal configuration which gives the least intersymbol interference characterized in that said optimal configuration of the parameters (c n+1 ) ) of the filter (1) which gives the least intersymbol interference is obtained by minimizing a cost function by means of self-decided symbols (a ) of the decision element (4) without knowledge n of the symbols actually transmitted and of the signal samples (z ) available at the filter output (1). n

Claim 3

Dependent Claim 34 words

Adaptive blind equalization method in accordance with claim 1 characterized in that said cost function is the mean square error existing between said self-decided symbols (â) n and said signal samples (z n ).

Claim 4

Dependent Claim 34 words

Adaptive blind equalization method in accordance with claim 1 characterized in that said cost function is the peak distortion existing between said self-decided symbols (a ) n and said signal samples (z n ).

Claim 5

Dependent Claim 39 words

Adaptive blind equalization method in accordance with claim 1 characterized in that the delay introduced by each of the delay lines of said filter (1) is equal to the signal transmission time and thus produces a synchronous signal equalization.

Claim 6

Dependent Claim 42 words

Adaptive blind equalization method in accordance with claim 1 characterized in that the delay introduced by each of the delay lines of said filter (1) is smaller than the signal transmission time, thus producing an equalization of signals with fractionary spacing cells.

Claim 7

Dependent Claim 33 words

Adaptive blind equalization method in accordance with claim 5 characterized in that the delay introduced by each of the delay lines of said filter (1) is equal to half the signal transmission time.

Claim 8

Dependent Claim 53 words

Adaptive blind equalization method in accordance with claim 1 characterized in that said optimal configuration of the parameters (c 1) of the filter (1) which minimizes the intersymbol interference is obtained by successive approximations and in that for some iterations adaptation of the parameters (c 1) of the filter (1) is not accomplished.

Claim 9

Dependent Claim 46 words

Adaptive blind equalization method in accordance with claim 7 characterized in that said iterations in which adaptation of the parameters (c 1) of the filter (1) is not accomplished are decided on the basis of the value assumed by a binary consent function (f n ).

Claim 10

Dependent Claim 42 words

Adaptive blind equalization method in accordance with claim 8 characterized in that said binary consent function (f ) is constructed by comparing the sign of a self-decided n error (e ) with the sign of a reference error (e ). n n

Claim 11

Dependent Claim 72 words

Adaptive blind equalization method in accordance with claim 9 characterized in that said self-decided error sign (ê n ) is obtained by comparing the signal samples (z n ) with n n the self-decided symbols (a ) while said reference error n sign (e ) is obtained by comparing the signal samples (z ) n n with a reference point ( n βsgnz n ) of the space of the n symbols.

Claim 12

Dependent Claim 27 words

Adaptive blind equalization method in accordance with claim 1 characterized in that said electrical signals codified in symbols are transmitted on two carriers at the same frequency.

Claim 13

Dependent Claim 21 words

Adaptive blind equalization method in accordance with claim 11 characterized in that said carriers at the same frequency are in quadrature.

Claim 14

Dependent Claim 19 words

Adaptive blind equalization method in accordance with claim 12 characterized in that said carriers in quadrature are amplitude modulated.

Claim 15

Dependent Claim 19 words

Adaptive blind equalization method in accordance with claim 13 characterized in that the number of said symbols is 16.

Claim 16

Dependent Claim 19 words

Adaptive blind equalization method in accordance with claim 13 characterized in that the number of said symbols is 64.

Claim 17

Dependent Claim 19 words

Adaptive blind equalization method in accordance with claim 13 characterized in that the number of said symbols is 256.

Claim 18

Dependent Claim 35 words

Adaptive blind equalization method in accordance with claims 8 and 13 characterized in that said binary consent function (f n ) has a real part (f n,R ) and an imaginary part (f n,I ).

Claim 19

Dependent Claim 63 words

Adaptive blind equalization method in accordance with claim 17 characterized in that said real part (f n,R ) and imaginary part (fn 1) of said binary consent function (f ) n, act independently of each other thus providing for adaptation of the real part and the imaginary part respectively of the parameters (c n+1 ) of the filter (1) independently of each other.

Claim 20

Dependent Claim 61 words

Adaptive blind equalization method in accordance with claim 17 characterized in that said real part (f n,R ) and imaginary part (f n,I ) of said binary consent function (f n ) act together thus providing for adaptation of the real part and imaginary part respectively of the parameters (c 1) of the filter (1) only when both give consent simultaneously.

Claim 21

Dependent Claim 114 words

Adaptive blind equalization method in accordance with claim 17 characterized in that said real part (f n,R ) of the binary consent function (f ) is constructed by comparing the n sign of the real part (ê n,R ) of a self-decided error with the sign of the real part (e n,R ) of a reference error (e n ) while said imaginary part (f n,I ) ) of the binary consent function (f ) is constructed by comparing the sign of the n imaginary part (ê n,I ) of a self-decided error (e ) with the n, n sign of the imaginary part (e n,I ) of a reference error (e n ).

Claim 22

Dependent Claim 210 words

Adaptive blind equalization method in accordance with claim 20 characterized in that said sign of the real part (ê n,R ) of the self-decided error (ê n ) is obtained by n comparing the real part (z n,R ) of said signal samples (z ) with the real part (â n,R ) of said self-decided symbols (â n ) n, n while said sign of the imaginary part (ê n,I ) of the self-decided error (e ) is obtained by comparing the n imaginary part (z n, I ) of said signal samples (z n ) with the imaginary part (â n,I ) of said self-decided symbols (â n ) and n, n the fact that said sign of the real part (e n,R ) of the reference error (e n ) is obtained by comparing the real part (z n,R ) of said signal samples (z ) with a reference point n ( n sgnz n ) of the symbol constellation plane while said sign of the imaginary part (e n,I ) of the reference error (e n ) is obtained by comparing the imaginary part (zn,I) ) of said signal samples (z ) with a reference point (β Ssgnz ) of the n n n symbol constellation plane.

Claim 23

Dependent Claim 62 words

Adaptive blind equalization method in accordance with claim 1 characterized in that said reception device comprises a second decision feedback filter (2) with adaptable parameters (g n+1 ) and that said parameters (g n+1 ) are adjusted until there is reached an optimal configuration having minimal intersymbol interference by minimization of said cost function constructed with said self-decided symbols (â n ).

Claim 24

Dependent Claim 64 words

Adaptive blind equalization method in accordance with claim 1 characterized in that said reception device comprises an automatic gain control block (6) and a carrier phase recovery block (7) of which the gain (G ) and phase n (Φ) respectively are adjusted until there is reached an n optimal configuration by minimization of said cost function constructed with said self-decided symbols (â n ).

Claim 25

Dependent Claim 21 words

Adaptive blind equalization method in accordance with claim 1 characterized in that said pilot vector (x ) is limited in amplitude.

Claim 26

Dependent Claim 30 words

Adaptive blind equalization method in accordance with claim 1 characterized in that said pilot vector (x ) is replaced by a vector made up of the signs of its components.

Claim 27

Dependent Claim 23 words

Adaptive blind equalization method in accordance with claim 9 characterized in that said self-decided error (e ) n is replaced by its sign.

Claim 28

Dependent Claim 101 words

Adaptive blind equalization device for the reception of electrical signals codified into symbols comprising a filter with adaptable parameters at the output of which there are signal samples, a decision element which assigns a symbol to each signal sample, and a control block which on the basis of a pilot vector of the signals received, if the signal samples and of the decided symbols regulates the adaptable parameters of the filter characterized in that said control block (5) comprises a first multiplier (28) which at each iteration enables or inhibits adaptation of the parameters (c n+1 ) of the filter (1).

Claim 29

Dependent Claim 101 words

Adaptive blind equalization device for the reception of electrical signals codified into symbols comprising a filter with adaptable parameters at the output of which there are signal samples, a decision element which assigns a symbol to each signal sample, and a control block which on the basis of a pilot vector of the signals received, if the signal samples and of the decided symbols regulates the adaptable parameters of the filter characterized in that said control block (5) comprises a first multiplier (28) which at each iteration enables or inhibits adaptation of the parameters (c n+1 ) of the filter (1).

Claim 30

Dependent Claim 57 words

Adaptive blind equalization device in accordance with claim 27 characterized in that it comprises a second decision feedback filter (2) with adaptable parameters (g n+1 ) and that said control block (5) comprises a second multiplier (29) which at each iteraton enables or inhibits adaptation of the parameters (g n+1 ) of the decision feedback filter (2).

Claim 31

Dependent Claim 73 words

Adaptive blind equalization device in accordance with claim 27 characterized in that it comprises an automatic gain control block (6) and a carrier phases recovery block (7) and that said control block (5) comprises a third multiplier (30) which at each iteration enables or inhibits adaptation of the gain (G ) of the automatic gain control n block (6) and the phase (¢_) of the phase recovery block of n the carrier (7).

Claim 32

Dependent Claim 39 words

Adaptive blind equalization device in accordance with claim 27 characterized in that said first multiplier (28) receives at one of its inputs a binary consent signal (f n ·ê n ) generated by a fourth multiplier (23). n n

Claim 33

Dependent Claim 53 words

Adaptive blind equalization device in accordance with claim 30 characterized in that said fourth multiplier (23) receives at a first input a self-decided error signal (e ) n coming from a first adder (10) and at a second input a binary consent function (f ) coming from a first decision n block (26).

Claim 34

Dependent Claim 49 words

Adaptive blind equalization device in accordance with claim 31 characterized in that said first decision block (26) receives at its input the output signal of a fifth multiplier (20) which in turn receives at its inputs the output signals of a first (18) and second (22) sign calculation block.

Claim 35

Dependent Claim 35 words

Adaptive blind equalization device in accordance with claim 32 characterized in that said first sign calculation block (18) receives at its input a reference error signal (e ) generated by a second adder (11). n

Claim 36

Dependent Claim 45 words

Adaptive blind equalization device in accordance with claim 33 characterized in that said second adder (11) receives at its noninverting input a signal sample (z ) n coming from said filter (1) and at its inverting input the output signal of a sixth multiplier (15).

Claim 37

Dependent Claim 43 words

Adaptive blind equalization device in accordance with claim 34 characterized in that said sixth multiplier (15) receives at its inputs the output of a third sign calculation block (12) and the output of a block (17) generator of a real quantity (S ).

Claim 38

Dependent Claim 33 words

Adaptive blind equalization device in accordance with claim 35 characterized in that said third sign calculation block (12) receives at its output a signal sample (z ) n coming from said filter (1).

Claim 39

Dependent Claim 49 words

Adaptive blind equalization device in accordance with claim 31 characterized in that said first adder (10) receives at its inverting input a self-decided symbol (e ) n coming from said decision device (4) and at its noninverting input a signal sample (z ) coming from said filter (1). n

Claim 40

Dependent Claim 59 words

Adaptive blind equalization device in accordance with claim 37 characterized in that said first multiplier (28) receives at one of its inputs a binary consent signal made up of a real part (f n,R · ê n,R ) generated by a fourth multiplier (23) and an imaginary part (f n,I ·ê n,I ) generated by a seventh multiplier (25).

Claim 41

Dependent Claim 127 words

Adaptive blind equalization device in accordance with claim 38 characterized in that said fourth multiplier (23) receives at a first input a real part signal (e n,R ) of a self-decided error (e ) coming from a first adder (10) and n at a second input a real part signal (f n,R ) of a binary consent function (f ) coming from a first decision block n (26) and that said seventh multiplier (25) receives at a first input an imaginary part signal ê n,I ) of a self-decided error (e ) coming from a first adder (10) and at a second n input an imaginary part signal (f n,I ) ) of a binary consent function (f ) coming from a second decision block (27). n

Claim 42

Dependent Claim 90 words

Adaptive blind equalization device in accordance with claim 39 characterized in that said first decision block (26) receives at its input the output signal of a fifth multiplier (20) which in turn receives at its inputs the output signals of a first (18) and a second (22) sign calculation block and that the second decision block (27) receives at its input the output signal of an eighth multiplier (21) which in turn receives at its inputs the output signals of a fourth (19) and a fifth (24) sign calculation block.

Claim 43

Dependent Claim 76 words

Adaptive blind equalization device in accordance with claim 40 characterized in that said first sign calculation block (18) receives at its input a real part signal (e n,R ) ) of a reference error (e ) generated by a second adder (11) n and that said fourth sign calculation block (19) receives at its input an imaginary part signal (e n,I ) ) of a reference error (e ) generated by a third adder (13). n

Claim 44

Dependent Claim 95 words

Adaptive blind equalization device in accordance with claim 41 characterized in that said second adder (11) receives at its noninverting input the real part (z n,R ) of a signal sample (z ) coming from said filter (1) and at its n inverting input the output signal of a sixth multiplier (15) and that said third adder (13) receives at its noninverting input the imaginary part (z n,I ) of a signal sample (z n ) n coming from said filter (1) and at its inverting input the output signal of a ninth multiplier (16).

Claim 45

Dependent Claim 77 words

Adaptive blind equalization device in accordance with claim 42 characterized in that said sixth multiplier (15) receives at its inputs the output of a third sign calculation block (12) and the output of a block (17) generator of a real quantity (β) and that said ninth multiplier (16) n receives at its inputs the output of a sixth sign calculation block (14) and the output of a block (17) generator of a real quantity (β n ).

Claim 46

Dependent Claim 71 words

Adaptive blind equalization device in accordance with claim 43 characterized in that said third sign calculation block (12) receives at its input the real part (z n,R ) of a signal sample (z ) coming from said filter (1) and that said n sixth sign calculation block (14) receives at its input the imaginary part (z n,I ) ) of a signal sample (z n ) coming from said filter (1).

Claim 47

Dependent Claim 108 words

Adaptive blind equalization device in accordance with claim 31 characterized in that said first adder (10) receives at its inverting input a self-decided symbol (â) made up of a real part (â n,R ) and an imaginary part (â n,I ) ) coming from said decision device (4) and at its noninverting input a signal sample (z ) made up also of a real part n (z n,R and an imaginary part (z n,I ) coming from said filter (1) and generates at its output a self-decided error signal (ê n ) made up of a real part (ê n,R ) and of imaginary part (ê n,I ).

Claim 48

Dependent Claim 53 words

Adaptive blind equalization device in accordance with claim 27 characterized in that said first multiplier (28) receives at one of its inputs a pilot vector (x ) and that upstream from said first multiplier (28) is inserted a limiter which limits the amplitude of the individual components of the pilot vector (x ).

Claim 49

Dependent Claim 50 words

Adaptive blind equalization device in accordance with claim 27 characterized in that said first multiplier (28) receives at one of its inputs a pilot vector (x ) and that upstream from said first multiplier (28) is inserted a seventh sign calculation block which extracts the pilot vector sign (x ).

Claim 50

Dependent Claim 34 words

Adaptive blind equalization device in accordance with claim 31 characterized in that upstream from said fourth multiplier (23) is inserted an eighth sign calculation block which extracts the self-decided error sign (ê n ).

Claim 51

Dependent Claim 53 words

Adaptive blind equalization device in accordance with one of claims 27 to 48 inclusive characterized in that said multipliers (15, 16, 20, 21, 23, 28, 29, 30), said adders (10, 11, 13), said sign calculation blocks (12, 14, 18, 19, 22, 24) and said decision block (26, 27) are accomplished with analog components.

Claim 52

Dependent Claim 53 words

Adaptive blind equalization device in accordance with one of claims 27 to 48 inclusive characterized in that said multipliers (15, 16, 20, 21, 23, 28, 29, 30), said adders (10, 11, 13), said sign calculation blocks (12, 14, 18, 19, 22, 24) and said decision block (26, 27) are accomplished with digital components.

Claim 53

Dependent Claim 23 words

Adaptive blind equalization device in accordance with claim 50 characterized in that said digital components are implemented in one or more integrated circuits.

Adaptive blind equalization method and device

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