Spread-spectrum signal demodulator
First Claim
1. A spread spectrum signal demodulator receiving a received signal including a plurality of spread spectrum signals, comprising:
- at least one first correlation detecting means for detecting correlations between spreading codes assigned to the respective spread spectrum signals contained in the received signal and the received signal; and
at least one interference canceller including;
at least one replica signal generating means for generating replicas of the respective spread spectrum signals contained in the received signal by causing respreading of the correlations detected by the first correlation detecting means in timed relation to respective symbol timings with the spreading codes;
at least one replica signal subtracting means for subtracting replica signals generated in the replica signal generating means from the received signal;
at least one second correlation detecting means for detecting correlations between a received signal after replica signal cancellation obtained from the replica signal subtracting means and the spreading codes assigned to the respective spread spectrum signals contained in the received signal; and
at least one signal strength suppressing means for multiplying a suppressing factor greater than or equal "0" and less than "1" connected at least one of between the first correlation signal detecting means and the replica signal generating means, between the replica signal generating means and the replica signal subtracting means, and between the replica signal subtracting means and the second correlation detecting means.
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Accused Products
Abstract
A spread spectrum signal demodulator receives a received signal including a plurality of spread spectrum signals, and comprises at least one signal strength suppressing means, which reduces a correlation signal outputted from a first correlation detecting means or replica signals until the correlation signal has been traveled through a replica signal generating means, a replica signal subtracting means and a second correlation detecting means. According to the invention, it is possible to improve interference cancellation capacity with a computational effort substantially comparable to that in a prior art replica signal cancellation system and improve interference cancellation performance with increasing number of interference cancellers irrespective of the magnitude of the correlation. With a sufficient number of interference cancellers provided, it is possible to obtain the same effect as obtainable with prior art decorrelation in a real time processing irrespective of the correlation magnitude.
114 Citations
18 Claims
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1. A spread spectrum signal demodulator receiving a received signal including a plurality of spread spectrum signals, comprising:
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at least one first correlation detecting means for detecting correlations between spreading codes assigned to the respective spread spectrum signals contained in the received signal and the received signal; and at least one interference canceller including; at least one replica signal generating means for generating replicas of the respective spread spectrum signals contained in the received signal by causing respreading of the correlations detected by the first correlation detecting means in timed relation to respective symbol timings with the spreading codes; at least one replica signal subtracting means for subtracting replica signals generated in the replica signal generating means from the received signal; at least one second correlation detecting means for detecting correlations between a received signal after replica signal cancellation obtained from the replica signal subtracting means and the spreading codes assigned to the respective spread spectrum signals contained in the received signal; and at least one signal strength suppressing means for multiplying a suppressing factor greater than or equal "0" and less than "1" connected at least one of between the first correlation signal detecting means and the replica signal generating means, between the replica signal generating means and the replica signal subtracting means, and between the replica signal subtracting means and the second correlation detecting means. - View Dependent Claims (2, 4, 6, 7, 8, 9, 10, 12, 13, 15, 17)
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3. A spread spectrum signal demodulator receiving a received signal including a plurality of spread spectrum signals, comprising:
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one first interference canceller receiving the received signal and zero symbols as input signals, correctively processing the input signals in a replica signal generating means, a replica signal subtracting means, a second correlation detecting means, and a signal strength suppressing means for multiplying a suppressing factor greater than or equal "0" and less than "1" and outputting a delayed received signal and detected symbols; and one second interference canceller receiving the received signal and symbols output from the first interference canceller as input signals, correctively processing the signals in a replica signal generating means, a replica signal subtracting means, a second correlation detecting means, and a signal strength suppressing means for multiplying a suppressing factor greater than or equal "0" and less than "1", and outputting a delayed received signal and detected symbols. - View Dependent Claims (5, 11, 14, 16, 18)
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Specification