Wireless Device Frame Transmission with Carrier Frequency Offset Pre-Compensation
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Solution Overview
Problem
In wireless local area networks (WLANs), especially with the IEEE 802.11ax standard, there is a challenge in maintaining robustness in outdoor channels and higher indoor efficiency due to carrier frequency and sampling frequency offsets, which cause performance degradation in multi-user scenarios.
Innovation Solution
A method is introduced where a wireless device pre-compensates carrier and sampling frequencies using carrier frequency offset (CFO) and sampling frequency offset (SFO) values, transmitted through RXVECTOR and TXVECTOR, to synchronize frames and minimize performance degradation. This involves estimating CFO values from received frames and applying them to transmitted frames to align frequencies, and calculating SFO from CFO to adjust sampling frequencies accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carrier frequency and sampling frequency offsets are not compensated, then device complexity is reduced, but transmission reliability deteriorates due to performance degradation in multi-user scenarios
Solution Approach 1:
The patent applies preliminary action by pre-compensating carrier frequency and sampling frequency offsets before frame transmission. The transmitting device calculates CFO and SFO values and applies compensation to the frame in advance, so that when the frame is received, the frequency offsets are already corrected, ensuring reliable reception without requiring complex real-time compensation at the receiver side.
Solution Approach 2:
The patent implements preliminary anti-action by applying counter-compensation to frequency offsets before transmission. The transmitting device measures or estimates the CFO and SFO values and applies opposite corrections to the transmitted frame, so that the frequency offsets are neutralized during reception, preventing performance degradation in multi-user scenarios.
2Reliability
If frequency offset compensation is applied to all transmitted frames, then transmission reliability is improved, but loss of time increases due to additional processing steps
Solution Approach 1:
The patent applies local quality by selectively applying frequency offset compensation only to specific frames that require it, rather than uniformly to all frames. The transmitting device determines which frames need compensation based on local conditions such as the presence of frequency offsets in previous frames or specific frame types, thereby reducing unnecessary processing time while maintaining transmission reliability where needed.
3Manufacturing precision
If carrier frequency offset compensation is performed, then manufacturing precision of frequency alignment is improved, but device complexity increases due to additional compensation mechanisms
Solution Approach 1:
The patent implements self-service by enabling the transmitting device to autonomously measure, calculate, and apply carrier frequency offset compensation without requiring external assistance or complex receiver-side correction mechanisms. The device performs CFO measurement, calculation, and compensation internally, achieving precise frequency alignment while keeping the overall system relatively simple.
Data Source
AI summary
A method for transmitting a frame is provided by a device in a wireless communication network. The device compensates a carrier frequency using a value of carrier frequency offset (CFO), and transmits a frame with the compensated carrier frequency to a receiver. The value of the CFO is indicated in TXVECTOR. A method for transmitting a frame is provided by a device in a wireless communication network. The device allocates data tones for a last symbol based on a payload size, generates the last symbol having repeated waveforms and transmits a frame including at least one period waveform of the repeated waveforms in the last symbol.