256-QAM Rate Matching via Fixed N Soft Parameter
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Solution Overview
Problem
Current LTE networks face challenges in supporting higher order modulation schemes like 256-QAM due to ambiguities in Radio Resource Control (RRC) configuration and increased signaling overhead, which can lead to incorrect demodulation of downlink control channels.
Innovation Solution
The solution involves using the same N soft value for rate matching patterns in both User Equipment (UE) and eNodeB, regardless of the 256-QAM configuration, and discarding additional parity bits to ensure seamless operation and correct demodulation during RRC configuration of 256-QAM, maintaining the same rate matching pattern and memory usage as in non-256-QAM schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If 256-QAM modulation scheme is implemented to increase data transmission rate, then productivity is improved, but device complexity increases due to changes required in downlink control signaling and rate matching patterns
Solution Approach 1:
The patent applies universality by using the same N soft value for rate matching patterns in both 256-QAM and non-256-QAM configurations. This allows the rate matching mechanism to serve multiple modulation schemes uniformly, eliminating the need for separate configuration sets and reducing control signaling complexity while maintaining support for higher data rates through 256-QAM
Solution Approach 2:
The patent changes the N soft parameter from being modulation scheme-dependent to being fixed across all modulation schemes. This parameter change simplifies the rate matching pattern determination and reduces the complexity of downlink control signaling while enabling 256-QAM operation
2Manufacturing precision
If different N soft values are used for 256-QAM and non-256-QAM schemes to optimize rate matching, then manufacturing precision is improved, but reliability decreases due to RRC configuration ambiguities and incorrect demodulation
Solution Approach 1:
The patent applies beforehand cushioning by pre-defining the N soft value to be used for rate matching in 256-QAM configurations before RRC configuration ambiguities can occur. This prevents demodulation errors by ensuring the UE and eNodeB use consistent rate matching patterns from the start of 256-QAM operation, eliminating the reliability issues caused by configuration ambiguities
3Reliability
If additional parity bits are retained in 256-QAM configuration to maintain error correction capability, then reliability is improved, but loss of substance increases due to higher signaling overhead
Solution Approach 1:
The patent extracts the N soft parameter from the modulation scheme-specific configuration and makes it a fixed, universal parameter. This extraction eliminates the need for additional signaling to convey different N soft values for 256-QAM, reducing signaling overhead while maintaining adequate error correction capability through appropriate code rate selection
Data Source
Figure 1A
Figure 1B
Figure 2~3
AI summary
Described is a UE to communicate with an eNB on a network, the UE comprising: an antenna to receive messaging from eNB indicating switching to 256-QAM scheme from an existing non-256-QAM scheme; and a table component for storing soft channel bits based on N soft such that the number and value of the soft channel bits for using the 256-QAM scheme is substantially equal to the number and value of the soft channel bits when the UE is not using the 256-QAM scheme. Described is an eNB comprising: an antenna to transmit messaging to a UE indicating switching to 256-QAM scheme from an existing non-256-QAM scheme; and an encoder to encode data using memory usage size based on N soft such that the number and value of the N soft for using the 256-QAM scheme is substantially equal to the number and value of the N soft when the eNB is not using the 256-QAM scheme.