Error signal quantization method and hardware for mixed blind an

Details Error signal quantization method and hardware for mixed blind an Error signal quantization method and hardware for mixed blind an

1995-12-21

1998-01-20

Chin, Wellington

Pulse or digital communications

Equalizers

Automatic

375235, 3647242, H04T 700

Patent

active

057107939

ABSTRACT:
According to a first aspect, a novel method of performing an eight point quantization is developed. The eight point quantization consists of selecting one eight specific points depending upon the phase of the measured complex error signal. According to a second aspect, a novel method of performing eight-point quantization of an error signal by rotating a measured complex sample point by positive pi/8 and by negative pi/8. Two sign comparisons results in two control signals. These control signals used in conjunction with the signs of the real and imaginary parts of the variable being quantized results in all the information necessary to select one of eight equal and radially symmetric decision regions. According to a third aspect, an efficient hardware circuit implements the complex coefficient update algorithm using the quantization method according to the first aspect on the error signal. The coefficient update circuit on a per tap basis requires four adders, eight multiplexors, two negation units, and two barrel shifters (if a programmable adaptation constant is supported). The equalizer filter requires a four multiplier control circuit for supply the multiplexor select signals. According to a fourth aspect, a raw error threshold is developed which indicates that for sample points received within a threshold distance T from a constellation point, the error signal for the equalizer coefficient update circuit is the difference vector in the measured error signal and the constellation point.

REFERENCES:
patent: 4027257 (1977-05-01), Perreault
patent: 4151491 (1979-04-01), McRae
patent: 4562425 (1985-12-01), Turner et al.
patent: 4630287 (1986-12-01), Armstrong
patent: 5243624 (1993-09-01), Paik et al.
patent: 5307375 (1994-04-01), Wu et al.
patent: 5537439 (1996-07-01), Choi

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