Uplink Transmit Power Management for Wireless Broadband Terminals
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Solution Overview
Problem
Existing wireless broadband customer-premises-equipment (CPE) terminals face challenges in meeting government emission rules for out-of-band spurious emissions while maintaining low cost, low power consumption, and reasonable size, as current solutions like high power linear amplifiers and channel filters are costly and inefficient for CPE terminals.
Innovation Solution
A method for optimizing up-link transmit power in wireless broadband CPE terminals by assigning transmit signals to sub-carriers with varying power levels based on their distance from the band edge, using guard bands to manage output power and reduce out-of-band emissions, allowing for increased transmit power without additional cost or size penalties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a high power linear amplifier is used to minimize intermodulation distortions, then transmit power and system link budget are improved, but cost, power consumption and device size increase
Solution Approach 1:
The patent applies local quality by implementing different power levels for different sub-carriers based on their position relative to the band edge. Sub-carriers near the band edge use lower power to minimize intermodulation distortions and out-of-band emissions, while sub-carriers in the center can use higher power. This localized power management allows the system to achieve high overall transmit power without requiring a high power linear amplifier, thus reducing device size and power consumption while maintaining good system link budget.
2Object-generated harmful factors
If a channel filter is used to filter out intermodulation distortions, then out-of-band spurious emissions are reduced, but cost increases and transmitter power decreases due to filter loss
Solution Approach 1:
The patent applies preliminary action by pre-adjusting the power levels of sub-carriers before transmission based on their distance from the band edge. By proactively lowering the power of sub-carriers near the band edge, the system prevents the generation of excessive intermodulation distortions and out-of-band emissions in the first place, eliminating the need for costly channel filters and avoiding power losses associated with filter attenuation.
3Object-generated harmful factors
If extra guard band is provided to band edge to allow higher transmit power, then emission rules are met, but spectrum efficiency decreases and system capacity is reduced
Solution Approach 1:
The patent applies dynamics by dynamically adjusting the power levels of sub-carriers based on real-time conditions such as terminal location, channel quality, and distance from the band edge. This dynamic power management allows the system to maximize spectrum utilization by transmitting at higher powers where appropriate (center sub-carriers with good channel conditions) while maintaining emission compliance through lower powers near the band edge, thereby increasing system capacity without violating emission rules.
Data Source
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AI summary
A method is disclosed for optimizing up-link transmit powers of a wireless broadband terminal operating in a predetermined frequency band in a multi-carrier system, the method comprising assigning a transmit signal to one or more sub-carriers of predetermined frequencies, and capping the output powers of the transmit signal to a predetermined level based on the predetermined frequencies, wherein the output power of the transmit signal is lower if frequencies of the transmit signal have less guard band to the edge of the predetermined frequency band.