Space-Time Encoding for OFDM Transmit Diversity

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Super 3G mobile telecommunications networks face challenges in achieving high data rates due to impairments such as phase noise, carrier frequency offset, and inter-carrier interference in OFDM systems, which hinder the application of higher modulation schemes and coding, making it difficult to meet target data rates.

Innovation Solution

The implementation of transmit diversity using Space-Time encoding in OFDM systems, which involves processing data symbols across multiple sub-carriers and antennas to provide frequency, time, and spatial diversity, mitigating impairments and enhancing data transmission reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If OFDM is used to achieve high spectral efficiency and high data rates, then spectral efficiency and data rate potential are improved, but the system becomes sensitive to impairments such as phase noise, carrier frequency offset, and inter-carrier interference

Engineering Contradiction:

Improvedata rateVSAvoidsystem performance under impairments

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies Space-Time encoding which transforms the transmission from a single-dimension (single antenna) to multi-dimension (multiple antennas with multiple transmit paths). This dimensional expansion provides diversity against impairments while maintaining high data rates through parallel sub-carrier transmission

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent combines multiple transmission paths with different characteristics (different antennas, different time slots, different frequency sub-carriers) to create a composite transmission system. This composite approach provides robustness against specific impairments while maintaining overall system performance

Inventive Principle:

Principle #40Composite materials

2Productivity

If higher modulation schemes and coding are applied to increase data rates, then data rate potential is improved, but the system becomes more vulnerable to impairments and SINR degradation

Engineering Contradiction:

Improvedata rateVSAvoidsensitivity to impairments and SINR reduction

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of impairments into a benefit by using Space-Time encoding to create multiple transmit paths. The impairments that would normally degrade higher-order modulation schemes are mitigated through diversity, allowing the system to successfully employ 64-QAM and turbo/LDPC coding to achieve high data rates

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If transmit diversity encoding is introduced to mitigate impairments, then reliability and SINR are improved, but device complexity increases

Engineering Contradiction:

Improvetransmission reliability and SINRVSAvoidencoding and decoding complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the data stream into blocks that are processed independently through Space-Time encoding. This segmentation allows the complexity to be managed in smaller units (block-by-block processing) rather than requiring complex processing of the entire data stream, making the diversity implementation more tractable

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8102933B2Transmit diversity scheme

Publication Date: 2012.01.24 LENOVO INNOVATIONS LTD (HONG KONG)

AI summary

The present invention relates to methods for implementing transmit diversity in a telecommunication network. In particular there is provided an algorithm for performing transmit diversity encoding in a transmitter (100) and transmit diversity decoding in a receiver (1700) respectively. In the method processed pairs of data blocks (314.1A, 314.1B) are transmitted on a first antenna (112.1) on N sub-carriers in a first temporal order; and a second antenna (112.2) in the reverse temporal order.