Reducing PAPR in OFDM Signal Fields via Header Bit Manipulation
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Solution Overview
Problem
The high peak-to-average power ratio (PAPR) in multi-carrier modulation signals, particularly in OFDM waveforms, leads to increased power amplifier back-off, inefficiency, and higher DC power demands, which is exacerbated in IEEE 802.11 standards, resulting in reduced mean envelope power and bit error performance degradation.
Innovation Solution
A wireless communication device and method that selectively changes header bits in a frame format to reduce the PAPR of signal field symbols, using a controller configured to manipulate data rate, reserved, data length, and service field bits within the physical layer convergence protocol, allowing for reduced PAPR without compromising data integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-carrier modulation (OFDM) is used to achieve high data rates and resistance to dispersion, then transmission performance is improved, but peak-to-average power ratio increases causing amplifier inefficiency and higher power demands
Solution Approach 1:
The patent applies parameter changes by selectively modifying header bits (data rate bits, reserved bit, data length bits) to alter the signal field symbol characteristics. This changes the PAPR parameter of the OFDM signal without affecting the payload data, thereby reducing peak power requirements while maintaining transmission rate benefits
Solution Approach 2:
The patent implements preliminary action by reducing PAPR in advance before the signal enters the power amplifier. By preprocessing the signal field symbol to achieve lower PAPR, the system prepares the signal to operate more efficiently through the amplifier, avoiding the need for excessive back-off and reducing overall power consumption
2Reliability
If power amplifier back-off is increased to maintain signal linearity and prevent clipping, then signal quality is improved, but transmission power and range are reduced
Solution Approach 1:
The patent changes the PAPR parameter of the signal field symbol through selective bit manipulation in the header. By modifying data rate bits, reserved bits, or data length bits, the signal achieves lower peak power characteristics while maintaining linear operation through the amplifier, thereby preserving signal quality without requiring excessive back-off
3Loss of energy
If header bits are modified to reduce PAPR, then power efficiency is improved, but data integrity may be compromised
Solution Approach 1:
The patent segments the frame structure into header portion and payload portion. By applying PAPR reduction techniques only to the header (signal field) and leaving the payload unchanged, the system improves power efficiency without affecting the integrity of the actual data being transmitted. The receiver can still correctly interpret the modified header bits according to the protocol specification
Solution Approach 2:
The patent creates a modified copy of the signal field symbol with altered header bits for PAPR reduction, while the payload remains as an unchanged copy. This allows the system to benefit from reduced PAPR in the header portion while preserving the original data integrity in the payload portion
Data Source
AI summary
The device, system and method reduce the peak-to-average power ratio (PAPR) of a signal field symbol in a multi-carrier modulation communication signal. The device includes an antenna, a transceiver coupled to the antenna, and a controller to cooperate with the transceiver and being configured to reduce the PAPR of the signal field symbol in the multi-carrier modulation communication signal. The controller is configured to transmit information using a frame format including a header and a data field, the header having a signal field and a service field each having a plurality of bits, the plurality of bits of the signal field defining the signal field symbol. The controller selectively changes at least the header bits to generate the signal field symbol with a reduced or lowest PAPR.