Adaptive Coding Bit Allocation for Wireless Channel State Feedback
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Solution Overview
Problem
Existing wireless mobile communication systems face challenges in minimizing operations for bit allocation and feedback information while maintaining high bit error rate performance, particularly in V-BLAST MIMO-OFDM systems, due to excessive feedback requirements and reduced transmission rates in schemes like ABPA and SBA.
Innovation Solution
The Adaptive Coding Bit Allocation (ACBA) technique selectively allocates bits to sub-channels based on channel state information, using a soft demapper for interference cancellation and controlling channel code rates to optimize bit allocation without increasing modulation levels, thus reducing feedback and operations while improving bit error rate performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ABPA scheme is used to optimize bit allocation based on channel state, then bit error rate performance is improved, but feedback information amount and operational complexity increase excessively
Solution Approach 1:
The patent extracts only the essential channel state information (channel gain magnitude) needed for bit allocation, discarding unnecessary feedback information such as phase information and detailed channel characteristics. This selective extraction maintains BER performance while significantly reducing feedback overhead and computational complexity compared to full ABPA implementation.
Solution Approach 2:
The patent applies different processing approaches to different parts of the communication system: simplified bit allocation based on channel gain magnitude is applied at the receiver, while the transmitter uses predetermined bit allocation tables. This local differentiation optimizes the overall system by applying complexity only where necessary for performance.
2Device complexity
If SBA scheme is used to reduce feedback information and operations, then operational complexity is reduced, but transmission rate decreases due to unallocated sub-channels
Solution Approach 1:
The patent changes the allocation parameter from binary selection (allocate or not allocate as in SBA) to proportional allocation based on channel gain magnitude. By using the channel gain value as a continuous parameter for bit allocation, the system achieves both reduced complexity and maintained transmission rate, avoiding the zero-allocation problem of SBA.
3Productivity
If higher-level modulation technique is applied to selected sub-channels to prevent transmission rate reduction, then transmission rate is maintained, but symbol error probability increases
Solution Approach 1:
The patent applies different modulation schemes to different sub-channels based on their channel gain magnitudes. Sub-channels with better channel conditions use higher-order modulation for higher rate, while sub-channels with poorer conditions use lower-order modulation for better reliability. This local adaptation optimizes both transmission rate and symbol error probability simultaneously.
Data Source
AI summary
Disclosed is a method for transmitting and receiving data according to a channel state in a wireless communication system, the method includes measuring a characteristic of transmission channels used for data transmission and transmitting channel state information of the measured channel characteristic; and selecting sub-channels for data transmission according to the channel state information, and transmitting data through the selected sub-channels.