Reception Device Frequency Domain Equalization Interference Management
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Solution Overview
Problem
In radio communication systems, the existing MMSE-FDE method struggles with inter-code interference and noise emphasis, leading to suboptimal error rates and throughput, especially when the delay variance of the propagation channel changes, and requires complex calculations to adapt modulation and coding schemes based on pre-equalization SNR.
Innovation Solution
A radio communication system and method where a reception device performs frequency domain equalization based on minimum mean square error, calculates the reliability of transmitted bits using mutual information from log likelihood ratios, and adjusts modulation schemes and coding rates post-equalization to improve error rates and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency domain equalization is performed by multiplying the inverse characteristic of the propagation channel, then inter-code interference is suppressed, but noise is colored and emphasized leading to worse transmission characteristics
Solution Approach 1:
The patent changes the equalization criterion from zero-forcing (multiplying inverse characteristic) to minimum mean square error (MMSE). This parameter change in the equalization approach balances the suppression of inter-code interference with the prevention of noise emphasis, achieving both goals simultaneously rather than trading one for the other.
Solution Approach 2:
The patent introduces feedback mechanisms where the reception device reports channel state information and quality metrics back to the transmission device. This feedback enables adaptive modulation and coding scheme selection, allowing the system to adjust transmission parameters based on actual channel conditions and equalization performance, thereby optimizing the balance between interference suppression and noise management.
2Reliability
If adaptive modulation scheme is used to allocate appropriate modulation scheme in response to reception situation, then transmission quality is controlled, but calculation complexity increases due to need for pre-equalization SNR calculation
Solution Approach 1:
The patent performs equalization and quality assessment in advance (pre-equalization) before final transmission parameter selection. By preparing channel state information and quality metrics beforehand, the system simplifies the adaptive modulation decision process and reduces real-time calculation complexity while maintaining accurate transmission quality control.
Solution Approach 2:
The patent introduces channel state information and quality metrics as intermediary parameters that mediate between the physical channel conditions and the modulation/coding scheme selection. These intermediaries simplify the decision-making process by providing standardized, pre-processed information that directly guides transmission parameter selection without requiring complex real-time calculations.
3Object-affected harmful factors
If single carrier scheme is used in uplink, then PAPR is reduced, but inter-code interference cannot be suppressed requiring adaptive equalization technique
Solution Approach 1:
The patent changes the equalization approach from complex adaptive equalization to simple frequency domain equalization using MMSE criterion. This parameter change in the equalization method enables effective inter-code interference suppression in single-carrier uplink transmissions without requiring complex adaptive algorithms, thus maintaining low PAPR while reducing computational complexity.
Data Source
AI summary
A reception device which receives a signal transmitted by a transmission device which changes at least one of a modulation scheme and a coding rate. The reception device includes an equalization unit which equalizes a received signal in frequency domain, a reliability calculation unit which calculates the reliability of a transmitted bit from the received signal after equalization, a mutual information amount calculation unit which calculates a mutual information amount based on the reliability of the transmitted bit calculated by the reliability calculation unit, and a notification signal generation unit which sets at least one of a modulation scheme and a coding rate based on the mutual information amount calculated by the mutual information amount calculation unit to generate a signal to be reported to the transmission device.