CFO Estimation in Wireless Data Transmission
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Solution Overview
Problem
In wireless communication systems, especially OFDM systems, accurately estimating Carrier Frequency Offset (CFO) is challenging in poor wireless channel conditions, leading to increased data packet error rates and decreased transmission rates due to fading and noise, particularly in mobile terminals.
Innovation Solution
A method and apparatus that estimate CFO by unit of packet, calculate an average CFO over a window period, and compensate the estimated CFO to improve data transmission accuracy and reduce errors, using a transmitter and receiver configuration that adjusts CFO based on channel state during TXOP periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CFO is estimated by unit of packet in poor wireless channel conditions, then data transmission can proceed, but CFO estimation accuracy deteriorates leading to increased packet error rates
Solution Approach 1:
The patent combines multiple CFO estimation results from different packets into a single averaged CFO value. By merging the estimation outcomes from multiple packets transmitted during a TXOP period, the system achieves more accurate CFO compensation than would be possible from a single packet estimation alone, thereby resolving the contradiction between maintaining transmission productivity and improving measurement precision.
Solution Approach 2:
The patent performs preliminary CFO estimation on multiple packets before final data restoration. By estimating CFO on each packet individually first, then averaging these preliminary estimates, the system prepares accurate compensation values in advance, which improves the final CFO correction accuracy without delaying the transmission process.
2Measurement precision
If average CFO is calculated over window period, then CFO estimation accuracy improves, but system complexity increases
Solution Approach 1:
The patent segments the TXOP period into discrete packet units, estimating CFO for each packet individually before averaging. This segmentation approach simplifies the overall process by breaking down the complex task of CFO estimation into manageable per-packet operations, making the averaging process computationally tractable and reducing overall system complexity while maintaining precision.
Solution Approach 2:
The patent applies partial averaging by selecting a specific window period containing a predetermined number of packets rather than averaging all possible packets. This partial action approach achieves sufficient CFO estimation accuracy without the excessive computational burden of processing all available data, thereby optimizing the balance between precision and complexity.
3Reliability
If CFO compensation is adjusted based on channel state, then transmission accuracy improves in poor conditions, but processing time increases
Solution Approach 1:
The system performs self-service by automatically adapting CFO compensation based on detected channel conditions without requiring external intervention or complex manual adjustments. The receiver autonomously estimates CFO, determines channel quality, and applies appropriate compensation, thereby improving transmission reliability while minimizing the time loss associated with manual or externally-managed compensation adjustments.
Data Source
AI summary
Provided is an apparatus and method for transmitting and receiving data. The method includes respectively estimating a carrier frequency offset (CFO) of data packets transmitted during a transmit opportunity (TXOP) period by a unit of a packet; calculating an average CFO of the estimated CFOs estimated during a window period for the data packets; and compensating an estimated CFO of a predetermined data packet to one of the estimated CFO of the predetermined data packet and the average CFO, and restoring the predetermined data packet.