Phase-Rotated OFDM for Low-Power Indoor 6 GHz Coverage
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Solution Overview
Problem
Low power indoor (LPI) devices operating in the 6 GHz band face range and coverage issues due to stringent Effective Isotropically Radiated Power (EIRP) Power Spectral Density (PSD) requirements, resulting in shorter range and smaller coverage areas compared to devices in the 2.4 GHz and 5 GHz bands.
Innovation Solution
The method involves encoding a source word to generate duplicate OFDM symbols with linear phase rotations and mapping encoded bits to multiple sets of frequency subcarriers, followed by inverse Fast Fourier Transform operations, to enhance signal transmission in the 6 GHz band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If LPI devices operate in the 6 GHz band with low power constraints, then regulatory compliance is achieved and interference to incumbent services is prevented, but transmission range and coverage area are significantly reduced
Solution Approach 1:
The patent combines multiple OFDM symbols carrying the same data segment into a single transmission unit. By merging redundant signal copies with different phase rotations, the system achieves signal diversity gain that extends transmission range while maintaining low power operation and regulatory compliance in the 6 GHz band.
Solution Approach 2:
The patent introduces phase rotation as an additional dimension to differentiate signal copies. Instead of simply repeating the same OFDM symbol, the invention applies linear phase rotations to create diverse signal versions that can be combined at the receiver, effectively extending coverage area without increasing transmit power.
2Power
If LPI devices use maximum permitted EIRP PSD in the 6 GHz band, then transmission power is maximized within regulatory limits, but coverage area remains limited compared to lower frequency bands
Solution Approach 1:
The patent merges multiple OFDM symbols containing the same encoded data segment but with different phase rotations. This combining process at the receiver provides signal diversity gain that effectively extends coverage area beyond what would be achievable with single-symbol transmission at maximum permitted power.
Solution Approach 2:
The patent creates multiple copies of the same data segment encoded in OFDM symbols, then transmits these copies with different phase rotations. The receiver combines these copies to achieve better signal reliability and extended coverage, effectively multiplying the impact of the transmitted power within regulatory constraints.
3Reliability
If duplicate OFDM symbols with linear phase rotations are generated and transmitted, then link budget is increased and coverage is extended, but signal processing complexity increases
Solution Approach 1:
The patent changes the phase parameter of OFDM symbols to create diverse signal versions. By applying linear phase rotations to duplicate symbols, the system achieves link budget improvement through diversity gain while maintaining a relatively simple processing approach that can be implemented with standard OFDM receivers.
Data Source
AI summary
Method and system method comprising encoding a source word to be transmitted in a data unit from a source station in a wireless network, generating a first OFDM symbol that carries a data segment corresponding to encoded bits of the source word, duplicating the first OFDM symbol to generate a second OFDM symbol that is a linear phase-rotated copy of the first OFDM symbol; and transmitting the data unit including the first OFDM symbol and the second OFDM symbol.