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Method and apparatus for signal demodulation and diversity combining of orthogonally modulated signals

A modulation signal and quadrature modulation technology, which is applied in space transmit diversity, diversity/multi-antenna systems, transmission control/equalization, etc., can solve problems not involving quadrature modulation signals, etc.

Inactive Publication Date: 2003-10-15
APPLE INC
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Problems solved by technology

However, none of these methods involve quadrature modulation signals

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  • Method and apparatus for signal demodulation and diversity combining of orthogonally modulated signals
  • Method and apparatus for signal demodulation and diversity combining of orthogonally modulated signals
  • Method and apparatus for signal demodulation and diversity combining of orthogonally modulated signals

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[0022] It is well known that in the IS-95 system data transmitted over the reverse channel from the mobile station to the base station at a bit rate of 9.6 kilobits per second (kbps) is encoded in a rate 1 / 3 convolutional encoder at a rate of 28.8 kbps / A sequence of symbols in seconds (ksps). After block interleaving, symbols at a rate of 28.8ksps are modulated with 64-ary quadrature modulation, producing 2 6 = one of 64 mutually orthogonal waveforms, resulting in modulation symbols at a rate of 4.8 modulation ksps. Each modulation symbol is called a Walsh symbol, including 64 Walsh chips, and a Walsh chip is the shortest identifiable element of a Walsh function, so an N-order Walsh function has 2 N Walsh chips. Thus, the Walsh chipping rate for these Walsh symbols is 307.2 kilochips per second (kcps).

[0023] Walsh chips at a rate of 307.2 kcps are subjected to direct-sequence spreading by adding each Walsh chip modulo 2 to a so-called long code, resulting in a chip rat...

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Abstract

For combining diversity path signals comprising symbols each modulated in accordance with one of a plurality of orthogonal (e.g. Walsh) functions, a diversity combiner includes, for each path, a demodulator to demodulate each modulated signal symbol in accordance with a selected one of the orthogonal functions, a phase estimator to estimate a phase rotation and amplitude of the diversity path signal from the demodulated signal, and a complex signal multiplier to derotate the phase and weight the amplitude of the diversity path modulated signal in dependence upon the estimated phase rotation and amplitude. The combiner sums real parts of the phase-derotated and weighted modulated signals of the diversity paths, demodulates the combined signal in accordance with all of the orthogonal functions, and selects the maximum demodulated signal for each symbol thereby to determine for the symbol the selected one of the orthogonal functions.

Description

technical field [0001] The present invention is related to signal demodulation and diversity combining techniques in communication systems using quadrature modulation. Background technique [0002] Although the present invention is applicable to such communication systems, it is particularly suitable for signal demodulation in the reverse channel or uplink (from mobile station to base station) in a Direct Sequence Code Division Multiple Access (DS-CDMA) cellular communication system as exemplified below Merge with diversity. This system complies with TIA / EIA (Telecommunications Industry Association / Electronic Industries Association) interim standard IS-95-A, "Mobile Station-Base Station Conformance Standard for Dual-mode Broadband Spread Spectrum Cellular System", hereinafter referred to as IS-95 system. As we all know, the reverse channel of the IS-95 system adopts 64-element quadrature modulation. Background technique [0003] In the DS-CDMA mobile cellular communicati...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04B1/7115H04B1/712H04B7/08H04B7/26
CPCH04B1/712H04B1/7115H04B7/0865
Inventor H·莱布
Owner APPLE INC
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