Modified Kerdock Codebook for MIMO Long-Range Wireless
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Solution Overview
Problem
Current MIMO wireless communication systems face significant computational overhead and signal outage issues due to the large number of digits in Grassmannian codebooks, which limits their effectiveness in long-range transmissions, especially in outdoor environments where channel state information is not fully utilized.
Innovation Solution
A modified Kerdock codebook is introduced, optimizing the use of channel state information and reducing signal outage by incorporating new codewords that enhance the transmit bit error rate (BER) and precoding gain, allowing for longer-range wireless communications up to several kilometers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Grassmannian codebook is used for precoding, then transmission reliability is improved due to large codeword distance, but computational overhead increases significantly due to large number of digits requiring extensive multiplications
Solution Approach 1:
The codebook design is segmented into two parts: a first codebook containing base codewords with simple structures, and a second codebook containing coefficient matrices. This segmentation allows the system to maintain reliability through the structured design while reducing computational complexity by separating the complex codeword generation into pre-computed components.
Solution Approach 2:
The invention changes the parameter representation from using many digits in Grassmannian codebooks to using a combination of simple base codewords and coefficient matrices. This parameter transformation reduces the number of multiplications required while maintaining the essential properties needed for reliable transmission.
2Reliability
If Grassmannian codebook is used, then codeword distance is maximized for optimal performance, but processing time increases leading to higher latency in communication system
Solution Approach 1:
The base codebook and coefficient matrices are pre-computed and stored, allowing the system to quickly generate precoding matrices during operation without performing extensive real-time calculations. This preliminary preparation reduces processing time and latency while maintaining the optimal codeword distance properties.
3Device complexity
If Kerdock codebook is used to reduce complexity, then computational overhead is reduced, but channel state information feedback requirements increase which interferes with data traffic
Solution Approach 1:
The invention uses a partial codebook approach where only essential base codewords and coefficient matrices are maintained, allowing the system to achieve good performance with reduced feedback requirements compared to full Grassmannian codebooks, while avoiding the excessive feedback overhead of traditional Kerdock codebooks.
4Reliability
If conventional codebooks are used for indoor MIMO systems, then performance is optimized for indoor environments, but effectiveness decreases in outdoor long-range transmissions where channel state information is not fully utilized
Solution Approach 1:
The precoding matrix design incorporates structures that are universally applicable across different environments. By using base codebooks and coefficient matrices that can adapt to various channel conditions, the system achieves both indoor and outdoor effectiveness, particularly improving long-range outdoor transmission where conventional codebooks fail to utilize channel state information effectively.
Data Source
AI summary
The solution of the present invention is a precoding that allows an optimal use of multiple-antennas in a MIMO system. The precoding uses codebooks that are optimized for long-range wireless transmissions. A modified Kerdock codebook {wkmi} allows further improvement of the precoding gain. The modified Kerdock codebook {wkmi} contains new codewords wkmi that have been modified in order to further improve the transmit bit error rate (BER). The modified codebook {wkmi} allows a precoding gain that is between 2-3 dB. The present invention improves the transmit bit error rate (BER) of a wireless system. It allows a longer range in outdoor MIMO systems. Less signal outage is the result which allows that wireless signals can be transmitted over several kilometers.