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CDMA receiver with parallel interference suppression and optimized synchronization

a receiver and parallel technology, applied in the direction of line-faults/interference reduction, transmission, electrical equipment, etc., can solve the problems of complex operation, structural complexity, and more complex operation

Inactive Publication Date: 2009-06-02
COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
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  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This approach significantly reduces operational complexity while maintaining synchronization acquisition speed, as synchronization signals are shared across all stages, and the use of sliding correlators and matched filters optimizes performance without increasing acquisition time.

Problems solved by technology

It is also possible to recover the symbol clock with the aid of a sliding correlator, but this is more complex.
Its disadvantage is its operational complexity, because its installation in the form of a finite pulse response digital filter (operating at the speed of the chips multiplied by the number of samples) requires N multiplications and N additions for each sample.
Thus, its structural complexity is linked with its operating complexity.
Although this arrangement makes it possible to obtain a correct operation of the receiver it is still relatively complex.

Method used

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  • CDMA receiver with parallel interference suppression and optimized synchronization
  • CDMA receiver with parallel interference suppression and optimized synchronization
  • CDMA receiver with parallel interference suppression and optimized synchronization

Examples

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Embodiment Construction

[0053]Use is made of a system with direct sequence spread spectrum and several optionally asynchronous transmitters. At the parallel interference suppression receiver, the correlation peak or peaks corresponding to the different propagation paths of the signal of user k are placed precisely at the same locations in the symbol window, no matter what the considered suppression stage for a given symbol. Thus, the signal received contains the replicas of the signal transmitted by the user k associated with the propagation paths, at a fixed location for a given symbol in the symbol window. The time positions are estimated in the synchronization means and can doubtless be considered as different between individual stages, because during the suppression stages interference is progressively removed from the signal. However, the information received does not move relative to the window of the considered symbol. Thus, a single synchronization signal per path is sufficient and not one per path...

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Abstract

A receiver for transmission and parallel interference has multiple access interference suppression stages having K channels, each comprising a correlation device corresponding to a particular pseudorandom sequence and interference generation and suppression device. Each stage delivers to the following stage signals at least partly freed from multiple access interferences. A decision stage receives the signals from the channels of the preceding suppression stage. Each decision stage has a correlation device corresponding to one of the pseudorandom sequences and decision device to deliver data. Devices for producing synchronization signals can control the interference suppression and the decision device. The devices producing the synchronization signals have components placed in the channels of the final stage. Further, the synchronization signals produced by these devices control the decision device of the channels of the final stage and the interference estimation device of the at least one interference suppression stages following appropriate time shifts.

Description

TECHNICAL FIELD[0001]The present invention relates to a CDMA (code division multiple access) receiver with parallel interference suppression and optimized synchronization.[0002]More generally, the invention relates to direct sequence spread spectrum (DSSS) digital transmission.[0003]The invention has applications in radiocommunications systems with mobiles, in wireless local area networks (WLAN), in wireless local loops (WLL), in cable television and online multimedia services, in integrated home systems and electronic funds transfer, etc.PRIOR ART[0004]Direct sequence spread spectrum consists of modulating each symbol of a digital signal by a binary pseudorandom sequence. Such a sequence consists of N pulses or chips, whose duration Tc is equal to Ts / N. The modulated signal has a spectrum spread over a range N times wider than that of the original signal. On reception, demodulation consists of correlating the signal with the sequence used on transmission making it possible to once ...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): H04B1/00H04B1/707
CPCH04B1/7093H04B1/7095H04B1/71075
Inventor OUVRY, LAURENTVARREAU, DIDIERLATTARD, DIDIERLEVEQUE, SEBASTIEN
Owner COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
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