MIMO Interleaver Design for Backward Compatibility
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing 802.11a/g wireless systems lack backward compatibility and efficient interleaving arrangements that balance compactness, low power consumption, and robustness when transitioning to 802.11n MIMO systems, which require multiple antennas to achieve high-throughput wireless LANs.
Innovation Solution
The development of interleavers and interleaving methods that parse data into multiple streams, allowing block interleaving and cyclic rotation to separate bits across antennas, ensuring backward compatibility while utilizing multiple transmit antennas to enhance spatial diversity and frequency separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single block interleaver is used for MIMO transmission, then device complexity is reduced, but reliability deteriorates due to inability to provide sufficient spatial diversity and frequency separation
Solution Approach 1:
The patent divides a single block interleaver into multiple independent block interleavers, with each interleaver processing a separate data stream for different transmit antennas. This segmentation enables each interleaver to independently provide frequency separation while the collection of interleavers across multiple antennas provides spatial diversity, thereby resolving the contradiction between reliability and complexity.
2Reliability
If multiple independent block interleavers are used for each antenna, then reliability improves through enhanced spatial diversity and frequency separation, but device complexity increases
Solution Approach 1:
The patent designs multiple block interleavers that share the same structural parameters and processing logic, allowing them to be implemented using a universal interleaver design. Each interleaver performs the same function of providing frequency separation, but when deployed across multiple antennas, they collectively provide additional spatial diversity. This universality reduces the incremental complexity compared to completely independent designs while maintaining improved reliability.
3Reliability
If data is transmitted using more transmit antennas than receive antennas, then spatial diversity is enhanced, but backward compatibility with SISO systems becomes difficult to maintain
Solution Approach 1:
The patent implements a dynamic system where the number of active transmit antennas and data streams can be adjusted based on receiver capabilities. When communicating with SISO receivers, the system dynamically activates only one transmit antenna and uses a single data stream, maintaining backward compatibility. When communicating with MIMO-capable receivers, the system dynamically activates multiple antennas and multiple streams to exploit spatial diversity, thus resolving the contradiction between enhanced reliability and adaptability.
Data Source
AI summary
The present invention, generally speaking, provides interleavers and methods of interleaving that satisfy the need for backward compatibility while effectively addressing competing design objectives. In accordance with one aspect of the invention, data is transmitted using a number of transmit antennas greater than an expected number of receive antennas. At least one pair of transmit antennas is formed, and multiple second data streams are formed from a first data stream, successive bits in said first data stream being assigned to different ones of said second data streams. Block interleaving of multiple respective ones of said second data streams is individually performed. During successive transmission intervals, the pair of transmit antennas is used to transmit a pair of data symbols taken from different ones of said second data streams, followed by an equivalent transformed pair of data symbols.