MIMO Stream Interleaving for Better Bit Separation
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Solution Overview
Problem
Standard 802.11a interleavers in wireless networks are inadequate for MIMO systems, as they do not provide sufficient separation between bits, leading to unrecoverable errors in adverse channel conditions such as fading and interference.
Innovation Solution
An improved interleaver design that increases the separation between adjacent bits and next adjacent bits by distributing them across different subcarriers and spatial streams, using a parser to apply distinct interleaving processes for each spatial stream, resulting in enhanced error correction capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard 802.11a interleaving is used, then device complexity is maintained at standard levels, but error correction capability deteriorates in MIMO systems due to insufficient bit separation
Solution Approach 1:
The patent divides the bit stream into multiple segments corresponding to different spatial streams, and applies separate interleaving processes to each segment. This segmentation allows each spatial stream to be independently interleaved, increasing the separation between adjacent bits from the standard approach and thereby improving error correction capability without requiring a complete redesign of the interleaver structure
Solution Approach 2:
The patent extends the interleaving concept from a single-dimensional approach (standard 802.11a) to a multi-dimensional approach by incorporating spatial stream separation. Bits are now separated not only in the frequency domain (subcarriers) but also in the spatial domain (different streams), effectively adding another dimension to the interleaving process and enhancing error distribution
2Reliability
If bits are closely packed to maintain high data rate, then productivity increases, but reliability decreases due to insufficient separation between adjacent bits in adverse channel conditions
Solution Approach 1:
By segmenting the bit stream into multiple spatial streams and applying independent interleaving to each, the patent achieves better error distribution without reducing the overall data rate. Each segment can be optimized for error resilience while maintaining the aggregate throughput
Solution Approach 2:
The patent modifies the interleaving parameters specifically for MIMO systems, adjusting the interleaving depth and pattern to achieve greater bit separation. This parameter optimization allows the system to maintain high data rates while improving reliability through enhanced error correction capability
Data Source
AI summary
A MIMO transmitter including an interleaving system for parsing encoded bits to a plurality of spatial streams and a plurality of interleavers to interleave bits for spatial streams such that at least a first spatial stream uses a first stream interleaver that interleaves with a pattern distinct from a second stream interleaver interleaving for a second spatial stream.