OFDM Carrier Grouping for Reception Level Shaping
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Solution Overview
Problem
Existing OFDM reception apparatuses struggle to directly identify carriers with actual errors and ascertain the reception level and error occurrence situation for each carrier group, as they require separate BER estimation and cannot directly apply detected BER to error threshold settings.
Innovation Solution
An OFDM reception apparatus and method that includes a reception state detection unit with a carrier analysis unit, which groups carriers and calculates representative reception levels and error information for each carrier group, allowing for direct identification of error occurrence situations and adjustment of modulation schemes or transmission gains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If BER estimation is performed separately for each carrier using noise level measurement, then the transmission rate can be maintained while achieving error immunity, but the device complexity increases due to separate BER estimation for each carrier
Solution Approach 1:
The patent divides carriers into multiple groups and performs BER estimation separately for each group rather than for each individual carrier. This segmentation reduces the computational complexity while maintaining error immunity by allowing differentiated modulation schemes and coding rates to be applied to each carrier group based on its specific BER characteristics.
2Reliability
If modulation scheme with small QAM values is selected to ensure error immunity, then transmission reliability improves, but the transmission rate is reduced due to fewer data bits per carrier
Solution Approach 1:
The patent applies different modulation schemes and coding rates to different carrier groups based on their specific BER characteristics. Carriers with good reception conditions can use higher-order modulation schemes (larger QAM values) to achieve higher transmission rates, while carriers with poor conditions use more robust but lower-rate schemes, thereby optimizing the overall transmission rate while maintaining error immunity.
3Reliability
If error correction code is used to protect against transmission errors, then reliability improves, but redundant data must be added which reduces the transmission rate
Solution Approach 1:
The patent applies different coding rates to different carrier groups based on their BER characteristics. Carrier groups with good reception conditions can use lower coding rates (less redundancy) to maintain higher transmission rates, while carrier groups with poor conditions use higher coding rates (more redundancy) to ensure error correction capability. This localized approach optimizes the balance between reliability and transmission rate.
Data Source
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AI summary
An OFDM reception apparatus (100) comprises: an OFDM demodulation unit (110); an error correction decoding unit (102); a reception level calculation unit (121) that calculates parameter values on a carrier-by-carrier basis as indices of reception state quality; an error information detection unit (122) that detects the state of transmission errors and their correction and outputs data series in error correction processing units; a group determination unit (131) that performs a grouping operation by dividing a frequency band to which carriers constituting the OFDM demodulated signal belong into a plurality of carrier groups by grouping consecutive carriers on a frequency axis and dividing the data series, in error correction processing units, into a continuous plurality of data groups; an error information measurement unit (133) that measures the output from the error information detection unit (122) in units of the data groups, for each of the plurality of data groups; and a reception level shaping unit (132) that calculates a representative value for each carrier group according to the parameter values output from the reception level calculation unit (121).