Time-frequency decoding unit
AssigneeFreescale Semiconductor, Inc.
InventorSamuel Kerhuel
Life of this patent
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Abstract
A decoding unit for decoding a signal modulating a plurality of symbols wherein each symbol carries a plurality of information which are code-division multiplexed in the time domain and in the frequency domain and wherein each information is associated with a known sequence of phase rotations, the phase in the known sequence varying deterministically between the plurality of symbols. The decoding unit first performs a phase rotation of the received plurality of symbols, then performs the time-domain despreading operation and finally performs the frequency-domain despreading operation. A processor, a receiver, a method and a computer program are also claimed.
Claims11
A decoding unit for decoding at least part of a signal transmitted over a communication channel of a wireless network, the signal modulating a plurality of symbols, each symbol being arranged to carry a plurality of information which are code-division multiplexed, each information being spreaded:
- in the frequency domain, across a given plurality of frequency carriers, based on a phase rotated version of a known code exhibiting constant-amplitude zero autocorrelation, CAZAC, property;
- and,
- in the time domain, across the plurality of symbols, based on one of a plurality of known orthogonal cover codes;
- wherein each information is associated with a known sequence of phase rotations, the phase in the known sequence varying deterministically between the plurality of symbols;
- the decoding unit comprising:
- a symbol control unit arranged to:
- receive the plurality of symbols and the associated sequence of phase rotations,
- determine a predefined reference symbol out of the received plurality of symbols;
- align the phase rotations, within each received sequence, on the phase rotation associated with the predefined reference symbol, thereby producing a plurality of aligned symbols;
- a time-domain despreading unit coupled to the symbol control unit and arranged to despread, in the time domain, the plurality of aligned symbols according to the known orthogonal cover codes;
- and,
- a frequency-domain despreading unit coupled to the time-domain despreading unit and arranged to despread, in the frequency domain, the time domain despreaded aligned symbols according to the known CAZAC codes.
A method of decoding at least part of a signal transmitted over a communication channel of a wireless network, the signal modulating a plurality of symbols, each symbol being arranged to carry a plurality of information which are code-division multiplexed, each information being spreaded:
- in the frequency domain, across a given plurality of frequency carriers, based on a phase rotated version of a known code exhibiting constant-amplitude zero autocorrelation, CAZAC, property;
- and,
- in the time domain, across the plurality of symbols, based on one of a plurality of known orthogonal cover codes;
- wherein each information is associated with a known sequence of phase rotations, the phase in the known sequence varying deterministically between the plurality of symbols;
- the method comprising:
- providing a processing unit, such as a processor, arranged to:
- receive the plurality of symbols and the associated sequence of phase rotations,
- determine a predefined reference symbol out of the received plurality of symbols;
- align the phase rotations, within each received sequence, on the phase rotation associated with the predefined reference symbol, thereby producing a plurality of aligned symbols;
- providing a time-domain despreading unit coupled to the processing unit and arranged to despread, in the time domain, the plurality of aligned symbols according to the known orthogonal cover codes;
- and,
- providing a frequency-domain despreading unit coupled to the time-domain despreading unit and arranged to despread, in the frequency domain, the time domain despreaded aligned symbols according to the known CAZAC codes.
Dependencies are inferred from the claim text.