Spread-spectrum communication device
AssigneeSharp Kabushika Kaisha
InventorHidenobu Fukumasa
Life of this patent
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Abstract
An example spread spectrum communication system is provided in which a transmission signal is separated into an I-phase component and a Q-phase component. In a complex spreading portion, spreading is performed by using multipliers and adders together with a sequence pattern of 1 and −1 appearing alternately. The outputs from the complex spreading portion are modulated in multipliers using pseudo-random sequences PN(k)(x) allotted for individual users. The baseband signal undergoes waveform shaping by roll-off filters and is modulated through a carrier modulator, then sent to a power amplifier, where it is amplified and transmitted via an antenna.
Claims21
A spread spectrum communication system including a transmitter and receiver for performing spread spectrum communications based on a direct sequence spreading scheme,
- the transmitter comprising:
- a complex spreading portion for multiplying an I-phase component signal and a Q-phase component signal of a transmission signal by a complex number sequence which will not cause any phase transition of signals on an I-Q plane in a direction toward the origin thereof;
- a multiplier for multiplying signals output from the complex spreading portion by a pseudo-random sequence which is generated at a speed exceeding a symbol rate of the transmission signal;
- a roll-off filter for waveform shaping;
- and
- a carrier modulator for performing carrier modulation of signals having undergone waveform shaping,
- the receiver comprising:
- a carrier demodulator for performing carrier demodulation of a signal received from the transmitter;
- a multiplier for multiplying signals of two types output from the carrier demodulator by the pseudo-random sequence;
- a complex despreading portion for performing despreading by multiplying the signals of each type by the complex number sequence;
- and
- a phase-correcting portion for performing phase-correction so as to extract the I-phase and Q-phase components,
- wherein the complex number sequence is a pattern by which the I-phase component is constantly set at 1 or −1 and the Q-phase component changes between 1 and −1 alternately.
A spread spectrum communication system including a transmitter and receiver for performing spread spectrum communications based on a direct sequence spreading scheme,
- the transmitter comprising:
- a permuting processor for permuting an I-phase component signal and a Q-phase component signal of a transmission signal once every two clock units and, at the same time, inverting the sign of one of the I-phase and Q-phase component signals;
- a multiplier for multiplying signals output from the permuting processor by a pseudo-random sequence which is generated at a speed exceeding a symbol rate of the transmission signal;
- a roll-off filter for waveform shaping;
- and
- a carrier modulator for performing carrier modulation of signals having undergone waveform shaping,
- the receiver comprising:
- a carrier demodulator for performing carrier demodulation of a received signal;
- and
- a multiplier for multiplying two types of signals output from the carrier demodulator by the pseudo-random sequence.
A spread spectrum communication apparatus for performing spread spectrum communications based on a direct spreading scheme, comprising:
- a complex spreading portion for multiplying an I-phase component signal and a Q-phase component signal of a transmission signal by a complex number sequence;
- a multiplier for multiplying the signals output from the complex spreading portion by a pseudo-random sequence which is generated at a speed exceeding a symbol rate of the transmission signal;
- a roll-off filter for waveform shaping;
- and
- a carrier modulator for performing carrier modulation of signals having undergone waveform shaping,
- wherein the complex number sequence is a pattern by which the I-phase component is constantly set at 1 or −1 and the Q-phase component changes between 1 and −1 alternately.
A spread spectrum communication apparatus for performing spread spectrum communications based on a direct sequence spreading scheme, comprising:
- a permuting processor for permuting an I-phase component signal and a Q-phase component signal of a transmission signal once every two clock units and, at the same time, inverting the sign of one of the I-phase and Q-phase component signals;
- a multiplier for multiplying signals output from the permuting processor by a pseudo-random sequence which is generated at a speed exceeding a symbol rate of the transmission signal;
- a roll-off filter for waveform shaping;
- and
- a carrier modulator for performing carrier modulation of signals having undergone waveform shaping.
A spread spectrum communication apparatus for performing spread spectrum communications based on a direct sequence spreading scheme, comprising:
- a carrier demodulator for performing carrier demodulation of a received signal;
- a multiplier for multiplying signals of two types output from the carrier demodulator by a pseudo-random sequence generated at a speed exceeding a symbol rate of the received signal;
- a complex despreading portion for performing despreading by multiplying the signals of each type by a complex number sequence;
- and
- a phase-correcting portion for performing phase-correction so as to extract I-phase and Q-phase components,
- wherein the complex number sequence is a pattern by which the I-phase component is constantly set at 1 or −1 and the Q-phase component changes between 1 and −1 alternately.
Dependencies are inferred from the claim text.