E-TFC Selection Power Backoff Lookup Table
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Solution Overview
Problem
The complexity of real-time E-TFC selection and memory-intensive storage of all possible transmitter configurations in portable communication devices for WCDMA uplink transmissions, leading to challenges in power control and adjacent channel leakage reduction.
Innovation Solution
A method for data rate selection that determines power backoff requirements and selects transport format combinations by using a lookup table to map transmitter configurations into a smaller set, allowing for efficient power control and reducing memory requirements, while maintaining specified ACLR levels through power amplifier linear headroom management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all possible E-TFCs for all possible transmitter configurations are calculated and stored offline, then complete power control coverage is achieved, but memory requirements become enormous
Solution Approach 1:
The patent extracts only the essential information needed for power control by creating a lookup table that maps transmitter configuration characteristics to power reduction values, rather than storing all possible E-TFC combinations. This selective extraction reduces memory requirements while maintaining sufficient power control coverage for practical applications.
Solution Approach 2:
The patent performs preliminary calculation of power reduction values for representative transmitter configurations and stores them in a lookup table. During real-time operation, the system queries this pre-computed table rather than calculating all possible E-TFCs offline, significantly reducing memory and processing requirements while maintaining adequate power control accuracy.
2Reliability
If all possible E-TFCs are calculated in real time, then accurate power control is achieved, but computational complexity becomes too high
Solution Approach 1:
The patent pre-calculates power reduction values for representative transmitter configurations and stores them in a lookup table. During real-time operation, the system simply queries this pre-computed table based on the current transmitter configuration characteristics, avoiding the need to calculate all possible E-TFCs in real time and significantly reducing computational complexity while maintaining adequate power control accuracy.
Solution Approach 2:
The patent creates a simplified lookup table that copies only the essential power reduction information for representative configurations, rather than storing or calculating all possible E-TFC combinations. This copying approach maintains sufficient power control accuracy for practical applications while dramatically reducing the computational burden during real-time operation.
3Adaptability or versatility
If multiple channels are used for uplink transmission, then transmission capability is improved, but adjacent channel leakage increases
Solution Approach 1:
The patent implements power control through maximum power reduction (MPR) calculations that provide feedback to the power amplifier. By continuously monitoring transmitter configuration characteristics and adjusting power levels based on pre-computed MPR values from the lookup table, the system maintains appropriate power levels to minimize adjacent channel leakage while preserving the ability to use multiple channels for enhanced transmission capability.
Data Source
AI summary
A method for data rate selection of a data transmission on a wide band code division multiple access (WCDMA) radio frequency (RF) channel in a portable communication device (100) is provided. The portable communication device (100) has transmitter circuitry (108) which includes a power amplifier (250). The method includes the steps of determining a power backoff requirement for the power amplifier (250) for a data transmission on a WCDMA channel (320) and selecting a transport format combination (TFC) for the data transmission in response to the power backoff requirement (324).