Cyclic Subcarrier Shift Transmit Diversity for Low PAPR SC-FDMA

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Solution Overview

Problem

Current mobile communication systems using the single carrier frequency domain multiple access (SC-FDMA) scheme face challenges in maintaining a low peak to average power ratio (PAPR) when transmitting data with multiple antennas.

Innovation Solution

The implementation of a transmission apparatus that includes a discrete Fourier transform (DFT) spreader, resource mapper, cyclic shift unit, and transmitter to generate and transmit frequency domain symbols, and an IDFT despreader, phase shift unit, and transmitter to manage phase shifts, ensuring low PAPR and effective transmit diversity using multiple antennas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple transmit antennas are used for transmit diversity in SC-FDMA systems, then transmission reliability is improved, but peak to average power ratio increases

Engineering Contradiction:

Improvetransmission reliabilityVSAvoidpeak to average power ratio

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The transmitted signal is segmented into multiple frequency domain streams, each processed independently through DFT spreading and resource mapping. Each antenna transmits a separate stream with controlled PAPR characteristics, avoiding the high PAPR that would result from direct multi-antenna transmission of the full signal.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies cyclic shifts to the frequency domain streams before IDFT transformation. This parameter change in the frequency domain translates to phase rotations in the time domain, enabling transmit diversity without altering the amplitude distribution and thus maintaining low PAPR characteristics.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If multiple transmit antennas are used for transmit diversity, then system performance is improved, but device complexity increases

Engineering Contradiction:

Improvesystem performanceVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs a universal DFT spreading and resource mapping structure that processes signals for multiple antennas through identical functional blocks. The same DFT spreader and resource mapper units are reused for each antenna stream, reducing overall system complexity compared to implementing separate processing chains for each antenna.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent transitions the diversity implementation from the time domain to the frequency domain by applying cyclic shifts to frequency domain streams. This dimensional change allows multiple antennas to transmit diverse signals without requiring complex time-domain processing or synchronization mechanisms.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS8526526B2Apparatus for transmission and reception with transmit diversity using cyclic subcarrier shift

Publication Date: 2013.09.03 ELECTRONICS & TELECOMM RES INST

AI summary

Provided is a technology adopting multiple transmit antennas in a radio communication system. In a mobile communication system of a signal carrier frequency division multiple access (SC-FDMA) scheme, it is possible to transmit data using the multiple transmit antennas, while maintaining a peak to average power ratio (PAPR) to be low. Also, it is possible to provide a new transmit diversity transmission even in a general radio communication system including an orthogonal frequency division multiple access (OFDMA), a code division multiple access (CDMA) scheme, and the like.