TX_TEQ Unit Adaptive Filtering ISI Reduction
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Solution Overview
Problem
Conventional COFDM systems face challenges in reducing inter-symbol interference (ISI) in wireless packet communication modems, where the TEQ process is not applicable due to the need for recalculating coefficients for each packet, leading to performance degradation and reduced transmission rates.
Innovation Solution
A wireless OFDM-based modem with a TX_TEQ unit that estimates the reception channel, calculates the TEQ coefficient, and applies it to data packets, allowing for adaptive filtering to reduce channel impulse response and ISI without requiring additional processing for each packet, thus enabling efficient TEQ process implementation in wireless communication protocols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a guard interval is inserted between adjacent symbols to reduce ISI, then ISI is reduced, but the data transmission rate is reduced
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing TEQ coefficients in a lookup table before actual data transmission occurs. The receiver estimates channel impulse response and computes the appropriate TEQ coefficient in advance, then applies it to subsequent data packets. This eliminates the need to recalculate coefficients for each packet, allowing the system to maintain shorter guard intervals while still reducing ISI effectively, thus improving data transmission rate without sacrificing reliability.
2Reliability
If TEQ process is applied to each data packet in wireless packet communication, then ISI is reduced, but processing time increases and transmission rate decreases
Solution Approach 1:
The patent implements preliminary action by performing channel impulse response estimation and TEQ coefficient calculation before data packet transmission. The receiver estimates the channel impulse response using training sequences or previous packets, computes the TEQ coefficient once, and stores it for use with subsequent data packets. This single calculation approach eliminates the need for repeated coefficient computation for each packet, significantly reducing processing time while maintaining ISI reduction effectiveness.
Solution Approach 2:
The patent employs feedback mechanisms where the receiver continuously monitors channel conditions and feeds this information back to the transmitter. Based on this feedback, the system adjusts the TEQ coefficients adaptively to match changing channel characteristics. This feedback loop allows the system to maintain optimal ISI reduction performance without requiring complete recalculations for each packet, as the coefficients can be updated based on feedback information rather than being recomputed from scratch.
3Reliability
If the interval between cyclic prefixes is increased to reduce ISI, then ISI is reduced, but the data transmission rate is reduced
Solution Approach 1:
The patent replaces the mechanical approach of increasing guard interval length with a signal processing substitution - applying TEQ coefficients to equalize the channel impulse response. Instead of physically extending the guard interval to accommodate longer channel responses, the system uses digital signal processing to compress and equalize the effective impulse response. This substitution allows the system to maintain short guard intervals while still achieving effective ISI reduction, thereby preserving data transmission rate.
Data Source
AI summary
A system, modem, receiver, transmitter and method for improving transmission performance. A coefficient may be calculated using a received signal. A process may be performed on at least one data packet scheduled for transmission based on the calculated coefficient. The process may improve transmission performance.