Wireless Transmission Device IQ Spreading Diversity

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Solution Overview

Problem

Wireless transmission methods using either frequency domain spreading or time domain spreading fail to achieve both frequency diversity and time diversity effects, leading to compromised interference resistance and increased reception error rates, especially in mobile communication systems where mobility and frequency selective fading are concerns.

Innovation Solution

A wireless transmission apparatus and method that modulates data into in-phase and quadrature component channels, spreads these components individually in their respective domains, and combines them, allowing for adaptive selection of spreading domains to optimize diversity effects based on propagation conditions and modulation schemes, thereby maintaining interference resistance and improving error rate performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If two-dimensional spreading is used to arrange spreading chips over a broad range in frequency and time domains, then frequency diversity effect and time diversity effect can be obtained, but orthogonality cannot be maintained and interference resistance cannot be increased to a practical level

Engineering Contradiction:

Improvereception sensitivityVSAvoidspreading chip arrangement complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the spreading chip arrangement into two independent one-dimensional domains: frequency domain spreading and time domain spreading. Instead of attempting complex two-dimensional spreading across both domains simultaneously, the invention divides the spreading operation into separate frequency-domain chips and time-domain chips, each arranged independently in their respective domains. This segmentation maintains orthogonality within each domain while avoiding the complexity and orthogonality loss of broad two-dimensional arrangement.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent extracts the frequency diversity and time diversity functions into separate spreading domains. Frequency diversity is achieved through frequency domain spreading of spreading chips, while time diversity is achieved through time domain spreading. By extracting these functions into separate one-dimensional domains rather than combining them into a complex two-dimensional arrangement, the invention maintains orthogonality while achieving both diversity effects.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If spreading factor is increased to improve interference resistance, then reception error rate decreases, but orthogonality becomes difficult to maintain when spreading chips are arranged over a broad range

Engineering Contradiction:

Improveinterference resistanceVSAvoidorthogonality maintenance

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent segments the spreading factor into two independent components: frequency domain spreading factor and time domain spreading factor. Each component operates independently in its own domain, allowing the total spreading factor to be increased for better interference resistance while maintaining orthogonality within each one-dimensional domain. This avoids the orthogonality loss that occurs when attempting to arrange a large number of spreading chips across a broad two-dimensional region.

Inventive Principle:

Principle #1Segmentation

3Reliability

If frequency domain spreading is used, then frequency diversity effect is obtained, but time diversity effect cannot be obtained

Engineering Contradiction:

Improvefrequency diversityVSAvoiddiversity effect coverage

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent merges frequency domain spreading and time domain spreading into a unified transmission scheme. Frequency domain spreading chips and time domain spreading chips are combined in the transmission signal, allowing the system to simultaneously achieve frequency diversity through frequency domain spreading and time diversity through time domain spreading. This merging of the two spreading approaches in separate domains provides both diversity effects without the complexity of two-dimensional spreading.

Inventive Principle:

Principle #5Merging (Combining)

4Reliability

If time domain spreading is used, then time diversity effect is obtained, but frequency diversity effect cannot be obtained

Engineering Contradiction:

Improvetime diversityVSAvoiddiversity effect coverage

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS7852903B2Wireless transmission device, wireless reception device, and symbol arranging method

Publication Date: 2010.12.14 OPTIS WIRELESS TECHNOLOGY LLC

AI summary

A wireless transmission device enabled to improve an error rate performance at a receiver, by acquiring at least one of frequency diversity effect and a time diversity effect while keeping the interference resistance which is acquired by diffusion. In this transmission device, a modulation unit (101) modulates data to create a modulation symbol having in-phase components and quadrature components. An IQ individual spreading unit (102) arranges the diffusion chips, which are obtained by spreading the modulation symbol, of the in-phase components and the quadrature components, in areas extending in diffusion domains set individually for the in-phase components and the quadrature components. An IQ combining unit (103) combines the arranged spreading chips of the in-phase components and the quadrature components.