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Spread-spectrum communication device

A technology of spread spectrum communication and direct sequence spread spectrum, which is applied in the field of portable phones and mobile communication systems, and can solve problems such as characteristic improvement

Inactive Publication Date: 2002-03-27
SHARP KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since the restriction on phase transition is effective only when the phase of the symbol does not change, the effect of restriction on phase transition is limited to one of the two transitions, so it is not possible to obtain a significant improvement on the characteristics

Method used

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no. 1 approach

[0036] image 3 is a block diagram of a first embodiment of a spread spectrum communication system according to the present invention, image 3 (a) and image 3 (b) represent the transmitter and receiver, respectively.

[0037] like image 3 As shown in (a), the transmitter includes a complex spread spectrum section 301 for performing complex spread spectrum modulation on the I-phase and Q-phase data Di and Dq of the transmitted signal, and multipliers 306 and 307 for utilizing the The pseudo-random sequence PN generated when the speed is equal to or greater than several times or hundreds of times the symbol rate (k) For data scrambling, roll-off filters 308 and 309 for waveform formation, a carrier modulator 316, a power amplifier 315 and an antenna 317.

[0038] The complex spreading section 301 includes a multiplier 305 for multiplying the I-phase data Di by a complex number sequence in which 1 and -1 alternately appear, and a multiplier 304 for multiplying the Q-phase ...

no. 2 approach

[0052] Figure 6 is a block diagram showing a second embodiment of the spread spectrum communication system according to the present invention. This spread spectrum communication system shows its transmitter including a multiplier 401 for multiplying I-phase data Di by -1, and a switch circuit 402 in place of the complex spread spectrum section 301 of the first embodiment. The other components are the same as in the first embodiment, so the same reference numerals are assigned as in the first embodiment. The switch circuit 402 has switches 403 and 404 controlled by a control signal.

[0053] The transmission signal is separated into I-phase and Q-phase components and input to the switch circuit 402 . The I-phase component is processed through a multiplier 401 to continuously generate its negative phase signal, which is also supplied to a switching circuit 402 .

[0054] The two switches 403 and 404 in the switch circuit 402 are adapted to operate in accordance with a contro...

no. 3 approach

[0057] Figure 8 is a block diagram showing a third embodiment of a spread spectrum communication system according to the present invention, wherein a mapping circuit is placed in image 3 (a) or Figure 6in front of the transmitter as shown. In the first and second embodiments, data is allocated to I-phase and Q-phase components as transmission data Di and Dq. However, for multimedia communications where W-CDMA is expected to be employed, multi-rate transmission, multi-code transmission, etc. are desirable in order to flexibly deal with various data rates.

[0058] Figure 8 Shows a mapping circuit 601 for generating parallel input data D (0) ,D (1) ,D (2) ,…D (N-1) The combination of symbols and input to image 3 (a) or Figure 6 in the transmitter.

[0059] Mapping circuit 601 is configured as many multipliers 603 to 604, 606 to 608, ..., multiple adders 605, 609, ..., and for generating orthogonal code C n circuit. Here, condition 2 is satisfied 1-1 1 A value ...

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Abstract

A spread-spectrum communication device which has a reduced size, consumes less power and is produced at low cost by suppressing variation of the amplitude of a signal and relaxing the linearity required by an amplifier. A transmission signal is divided into an I-phase component and a Q-phase component. A complex spectrum-spreading unit (301) spreads the spectrum by means of multipliers (304, 305) and adders (302, 303) by using a series pattern in which 1 and -1 alternately appear. The output of the complex spectrum-spreading unit (301) is modulated by multipliers (306, 307) by using a pseudo-random series PN<(k)> (x) assigned to each user. A baseband signal shaped in waveform by roll-off filters (308, 309) is modulated by a carrier modulation unit (316), sent to and amplified by a power amplifier (315), and transmitted from an antenna (317).

Description

technical field [0001] The present invention relates to a spread spectrum communication system based on a direct sequence spread spectrum scheme, used for example in portable telephones and mobile communication systems. Background technique [0002] In recent years, research and development on a mobile communication system utilizing a spread spectrum technique based on a direct sequence spread spectrum scheme has been widely conducted. Such communication systems include a system used worldwide and known as cdmaOne, a W-CDMA system and a wideband cdmaOne (cdma2000) system, both of which are aimed at the IMT-2000 standard (see Tero Ojanper and Ramjee Prasad, "An Overview of Air Interface Multiple Access for IMT-2000 / UMTS", IEEE Communications Magazine, September 1998. etc.). Among them, especially for W-CDMA, it is required to use a roll-off filter with a small roll-off ratio in order to reduce the required bandwidth to be as small as possible relative to the chip rate. As ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/20H04B1/707H04J13/16H04L27/22H04W52/00H04W72/04H04W76/02
CPCH04J13/0022H04B2201/70706H04B1/707
Inventor 福政英伸
Owner SHARP KK
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