Nonlinear Code Sets for MIMO ACK/NACK Error Protection

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Solution Overview

Problem

Current MIMO systems face challenges in providing sufficient error protection for ACK/NACK messages, leading to higher error rates or increased transmit power when using existing ten-bit repetition coding schemes for multiple MIMO streams.

Innovation Solution

The implementation of optimal nonlinear code sets with specific Hamming distances, such as C 10,6,6 for 2-stream, C 10,10,5 for 3-stream, and C 10,10,4 for 4-stream MIMO scenarios, which provide enhanced error protection by optimizing the number of coding bits and maintaining reliable message transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ten-bit repetition coding is used for MIMO ACK/NACK messages, then error protection is provided, but error rates increase or transmit power must be increased when multiple MIMO streams are involved

Engineering Contradiction:
Improveerror protectionVSAvoiderror rate
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The patent changes the coding scheme from simple repetition coding to optimal nonlinear code sets with specific Hamming distances. For 2-stream MIMO, it uses C(10,6,6) codes; for 3-stream, C(10,10,5) codes; and for 4-stream, C(10,10,4) codes. This parameter change in the coding structure provides sufficient error protection without increasing error rates or requiring higher transmit power.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If ten-bit repetition coding is used for MIMO ACK/NACK messages, then error protection is provided, but transmit power must be increased to maintain reliable message transmission

Engineering Contradiction:
Improvemessage transmission reliabilityVSAvoidtransmit power
Core Design Contradiction:
ReliabilityVSPower

Solution Approach 1:

The patent introduces optimal nonlinear code sets with specific parameters (C(10,6,6) for 2-stream, C(10,10,5) for 3-stream, C(10,10,4) for 4-stream MIMO) that provide sufficient error protection through optimized Hamming distances. This coding optimization maintains reliable message transmission without requiring increased transmit power, thereby resolving the contradiction between reliability and power consumption.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If existing coding schemes are used for multiple MIMO streams, then message transmission is maintained, but coding bits are not optimized leading to inefficiency

Engineering Contradiction:
Improvecoding efficiencyVSAvoidmessage transmission reliability
Core Design Contradiction:
ProductivityVSLoss of information

Solution Approach 1:

The patent optimizes coding bits for multiple MIMO streams by implementing stream-dependent coding schemes. For 2-stream MIMO, it uses C(10,6,6) codes; for 3-stream, C(10,10,5) codes; and for 4-stream, C(10,10,4) codes. This optimization improves coding efficiency while maintaining message transmission reliability through appropriately designed Hamming distances for each stream configuration.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2070242B1Optimal error protection coding for MIMO ACK/NACK/pre/post information
Publication Date: 2016.06.29 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP2070242B1 patent drawingFigure 1~3
  • EP2070242B1 patent drawingFigure 4
  • EP2070242B1 patent drawingFigure 5~7

AI summary

Error protection based on a nonlinear code set may be used in a multiple input multiple output (MIMO) radio communications system. A decoder decode received MIMO data streams and generates an automatic repeat request (ARQ) message for data units received for the MlMO data streams for each transmission time interval. An encoder codes the ARQ message using a code word from a nonlinear code set. At the data transmitter, which transmits one or more data uni in transmission time intervals from two or more MIMO data streams, the ARQ message associated with the transmitted data units is decoded using a code word from the nonlinear code set.