MIMO-OFDM Bit Interleaving Across Antennas for Decoder Diversity

Solution Overview

Problem

In MIMO-OFDM wireless communication systems, existing methods that parse data streams prior to interleaving do not guarantee that adjacent bits are mapped to non-adjacent carriers on different antennas, reducing frequency and spatial diversity, which affects the performance of convolutional decoders.

Innovation Solution

A system and method that first map bits into symbols and then parse these symbols into separate streams for multiple antennas, using a bit interleaver that interleaves over all bits in an OFDM symbol across antennas, a bit-to-symbol mapper, and a parser that sends symbols to different antennas, ensuring adjacent bits are mapped to non-adjacent carriers and avoiding long runs of low-reliability bits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If data streams are parsed prior to interleaving, then the system complexity is reduced and processing is simplified, but frequency and spatial diversity are reduced

Engineering Contradiction:

Improveinterleaving system complexityVSAvoidfrequency and spatial diversity

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent inverts the conventional processing order by performing interleaving before parsing. Specifically, the bit interleaver interleaves coded bits across all Nt antennas and all OFDM symbols before the parser distributes bits to individual antennas. This reversal ensures that adjacent coded bits are mapped to non-adjacent carriers on different antennas, maximizing frequency and spatial diversity while maintaining system simplicity.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent merges the interleaving operation across all antennas and OFDM symbols into a single unified interleaving process. The bit interleaver operates on the combined stream of coded bits from all antennas simultaneously, creating a unified interleaving pattern that ensures optimal diversity distribution across the MIMO-OFDM system without requiring separate interleavers for each antenna.

Inventive Principle:

Principle #5Merging (Combining)

2Device complexity

If separate interleaving is performed over each antenna, then the device complexity is reduced, but the performance of convolutional decoders deteriorates

Engineering Contradiction:

Improveinterleaving structureVSAvoidconvolutional decoder performance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent inverts the conventional processing order by performing interleaving before parsing. Specifically, the bit interleaver interleaves coded bits across all Nt antennas and all OFDM symbols before the parser distributes bits to individual antennas. This reversal ensures that adjacent coded bits are mapped to non-adjacent carriers on different antennas, maximizing frequency and spatial diversity while maintaining system simplicity.

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of operation

If adjacent bits are mapped to adjacent carriers on the same antenna, then the mapping process is simplified, but frequency diversity is reduced

Engineering Contradiction:

Improvebit mapping processVSAvoidfrequency diversity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent inverts the conventional processing order by performing interleaving before parsing. Specifically, the bit interleaver interleaves coded bits across all Nt antennas and all OFDM symbols before the parser distributes bits to individual antennas. This reversal ensures that adjacent coded bits are mapped to non-adjacent carriers on different antennas, maximizing frequency and spatial diversity while maintaining system simplicity.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent segments the coded bit stream into Nt parallel streams after unified interleaving, with each stream being parsed to a specific antenna. The parser distributes the interleaved bits to Nt output streams in a round-robin fashion, ensuring that bits intended for different antennas are properly separated while maintaining the diversity benefits of the unified interleaving process.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8527855B2Interleaving and parsing for MIMO-OFDM systems

Publication Date: 2013.09.03 KONINKLIJKE PHILIPS NV

AI summary

A wireless bit-interleaved coded OFDM (BI-COFDM) multiple-in-multiple-out (MIMO) system that improves the diversity seen by a convolutional decoder. The bit stream is interleaved first, then bits are mapped into symbols and then symbols are parsed into Nt separate streams, where t is the number of transmitters. A deinterleaver then performs the inverse permutation before sending the symbols to a Viturbi decoder. In another embodiment, a transmitting side bit-interleaver transforms an encoded and punctured bit stream using a first permutation, groups the transformed bit stream according to a desired constellation on one of Nt antennae, splits the transformed bit stream into separate streams accordingly and bit-interleaves/symbol-maps using a plurality of bit-interleavers/symbol-mappers to permute each stream using a second permutation. A receiving side performs the inverse operations of the transmitting side.