Emission Power Control for Packet Retransmissions
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Solution Overview
Problem
In UMTS systems, power scaling during data packet transmission leads to increased block error rates due to insufficient energy, especially when retransmissions occur, as existing methods fail to account for the missing energy, resulting in suboptimal transmission quality and interference.
Innovation Solution
Determine a nominal emission power relative to the reception quality and adjust it based on the difference between effective and nominal emission powers, allowing for adaptive power adjustment during retransmissions to ensure equal total energy at the receiver, thereby reducing interference and enhancing transmission capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power scaling is applied during data transmission to prevent exceeding maximum emission power, then the emission power limit is maintained and amplifier distortion is avoided, but the total energy received decreases and block error rate increases
Solution Approach 1:
The invention performs preliminary action by determining the energy shortfall caused by power scaling before retransmission, and pre-calculating the required power adjustment for the retransmission to compensate for this shortfall. This ensures that the retransmission is properly powered from the outset rather than reacting to errors after they occur.
Solution Approach 2:
The invention implements feedback by using the actual effective emission power and the determined energy shortfall information to adjust the retransmission power. The system feeds back the energy shortfall determination to the retransmission process, creating a closed-loop control that ensures the target energy level is achieved despite initial scaling.
2Power
If uniform power scaling is applied to all channels when power limit is threatened, then the emission power limit is respected, but the energy of transmitted packets is insufficient and error rate increases
Solution Approach 1:
The invention applies local quality by differentiating between first transmissions and retransmissions in terms of power handling. While first transmissions may be uniformly scaled to meet power limits, retransmissions receive localized quality improvement through energy shortfall compensation, ensuring they achieve the necessary energy level for reliable reception.
Solution Approach 2:
The invention changes parameters by adjusting the emission power specifically for retransmissions based on the determined energy shortfall. The system modifies the power parameter dynamically - maintaining uniform scaling for initial transmissions but applying a compensating power increase for retransmissions to restore the target energy level.
3Power
If slot-based scaling is used to reduce total emission power, then the power limit is maintained, but the energy of each packet is reduced and reception quality deteriorates
Solution Approach 1:
The invention performs preliminary determination of the energy shortfall caused by slot-based scaling before the retransmission occurs. This preliminary assessment allows the system to pre-calculate the exact compensation needed, ensuring that the retransmission is properly powered to achieve target reception quality.
Solution Approach 2:
The invention implements feedback by using the determined energy shortfall information to adjust retransmission power settings. The system feeds back the magnitude of energy loss due to scaling into the retransmission power calculation, creating a corrective mechanism that restores reception quality despite the initial power reduction.
Data Source
AI summary
A method of transmitting data packets in a radio system between and emitter and a receiver. A nominal emission power for a data packet is determined according to a desired reception quality. The data packet is transmitted with an effective emission power. A new nominal emission power defined according to the reception quality for the transmission is calculated, taking into account the effectively applied emission power and the pre-determined nominal emission power. The data packet is retransmitted with the nominal emission power.