Receiver apparatus for CDMA communication system

Details Receiver apparatus for CDMA communication system Receiver apparatus for CDMA communication system

1998-10-19

2001-07-17

Ghebretinsae, Temesghen (Department: 2631)

Pulse or digital communications

Spread spectrum

Direct sequence

C370S335000, C370S342000

Reexamination Certificate

active

06263012

ABSTRACT:

DETAILED DESCRIPTION OF THE INVENTION
1. Field of the Invention
The present invention relates to a receiver apparatus for code-division-multiple-access (CDMA) communication system, particularly to a receiver apparatus having an analog matched filter for demodulation and a rake combiner for multi-path signal.
2. Prior Art
Spread spectrum communication systems have gained a lot of attention in the field of mobile communication and wireless local area network (LAN) due to their high frequency efficiency and capabilities.
In the CDMA communication, the transmission signal is multiplied by a spreading code and the received signal is despread by the same spreading code at the receiver side.
A complex matched filter is used to perform the despread in high speed operation. A matched filter of digital circuit is large in circuit size and consumes a lot of electrical power. The inventors of the present invention proposed matched filters of a high speed and low power by analog multiplication and addition comparison to the circuit's in the Japanese patent publication 06-164321, 06-164320 and 07-212438.
A multi-path signal is generated by an original radio wave impinging surrounding buildings and other structures and causing a reflection of the original radio wave. A plurality of correlation peaks occurs within one symbol period when the multipath signal is despread by the matched filter. A plurality of correlation peaks of higher levels are selected for each complex component, synchronized and combined. The path selection and rake combining are performed by a digital circuit, so the complex components, i.e., in-phase and quadrature components of the output of the analog matched filter, have to be converted by an A/D converter into a digital data. At least a pair of A/D converters which has a higher speed than the chip rate when an over-sampling is executed, is necessary. However, this has an adverse effect of decreasing the electrical power.
SUMMARY OF THE INVENTION
An of the present invention to provide circuits for multi-path detection and phase compensation of a small circuit size and low electrical power consumption.
According to the present invention, an output having a complex matched filter is converted into a signal of one dimension and the multi-path detection is performed according to the signal. The analog complex components of the output from the matched filter is held at its peaks by an analog sampling and holding circuit and is converted into digital signals.


REFERENCES:
patent: 5974038 (1999-10-01), Shou et al.
patent: 6064690 (2000-05-01), Zhou et al.

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