PAPR Reduction via Sub-band Segmentation and Phase Shifting
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Solution Overview
Problem
Wireless communication systems face challenges in maintaining error-free signal processing due to significant variations in signal magnitude and power over time, leading to difficulties in gain control and proper signal reception, particularly in long range and low rate wireless links like smart metering applications, where extreme PAPR (Peak to Average Power Ratio) can hinder reliable communication.
Innovation Solution
The implementation of a method to reduce PAPR by multiplying signals with a sequence of constant coefficients (+1, -1, j, -j) across multiple sub-bands and applying a phase ramp or time-domain cyclic shift, allowing for efficient transmission and reception of packets in wireless communication systems, including smart meter stations, to minimize signal variations and enhance processing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If signals are transmitted with high power to maintain long-range communication, then communication range is improved, but PAPR increases causing gain control difficulties
Solution Approach 1:
The patent segments the transmitted signal into multiple packets distributed across different sub-bands. By dividing the original signal into smaller components (packets) and transmitting them separately across multiple sub-bands, the peak power of individual packets is reduced while maintaining the overall communication range through cumulative transmission energy.
Solution Approach 2:
The patent transforms the signal from a single-time-dimension transmission to a multi-dimensional transmission across multiple sub-bands and time slots. Packets are distributed across frequency sub-bands and transmitted at different times, reducing PAPR in the time domain while maintaining communication range through spatial-frequency diversity.
2Length of stationary object
If signal power is increased to overcome path loss, then transmission distance is improved, but gain control accuracy deteriorates
Solution Approach 1:
The transmission is segmented into multiple packets with reduced individual power levels. Each packet experiences less severe power variations, enabling more accurate gain control at the receiver while the cumulative effect of multiple packets maintains the required transmission distance.
Solution Approach 2:
The patent employs periodic transmission of packet sequences across different sub-bands. This periodic structure allows the receiver to use training packets and repetition packets for gain control calibration, improving measurement precision through repeated measurements and averaging.
3Reliability
If packets are transmitted across multiple sub-bands to reduce PAPR, then signal processing reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple packets across different sub-bands to reconstruct the original signal. By merging the energy and information from multiple lower-power packets transmitted across sub-bands, the system achieves reliable signal processing while managing device complexity through unified reception and combination processing.
4Ease of operation
If signal magnitude variations are reduced through PAPR reduction, then gain control becomes easier, but transmission efficiency decreases
Solution Approach 1:
The original signal is segmented into multiple packets that can be independently processed with simplified gain control. Each packet has reduced magnitude variations, making gain control easier, while the segmentation enables parallel processing across sub-bands to maintain overall transmission efficiency.
Solution Approach 2:
The patent applies preliminary PAPR reduction processing to packets before transmission by distributing them across sub-bands. This preliminary action reduces the peak power of individual packets, making subsequent gain control easier, while the structured distribution maintains transmission efficiency through optimized resource allocation.
Data Source
AI summary
Selective processing of one or more packets to be transmitted from a wireless communication device to another wireless communication device is effective to reduce the peak to average power ratio (PAPR) of the transmission. The one or more packets are transmitted via two or more sub-bands of an available transmission medium. The number of coefficients or factors within that sequence corresponds to the number of sub-bands via which the one or more packets are to be transmitted. Also, a phase ramp or time-domain cyclic shift may be added to one or more of the packets after having undergone multiplication by one of the coefficients or factors within the sequence.