Rate Control Method for Uplink Data Transmission
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Solution Overview
Problem
In cellular wireless systems, closed-loop rate control for uplink data transmission in W-CDMA networks experiences errors due to limitations in transmission power and severe fading, leading to synchronization breakdown between the base station and user equipment (UE), resulting in excessive or inadequate transmission power and low data throughput.
Innovation Solution
The method involves periodically resetting the data transmission rates of both the base station and UE to a reference rate and transmitting both absolute and differential rate corrections, with differential corrections being transmitted more frequently, to maintain synchronization and reduce errors in signaling the maximum data transmission rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If differential rate correction is transmitted frequently to maintain synchronization, then synchronization accuracy is improved, but transmission overhead and error probability increase
Solution Approach 1:
The patent applies preliminary action by having the base station pre-generate and store multiple differential rate correction values before transmission. The UE also pre-calculates expected rate corrections based on channel conditions. This preparation allows both parties to have matching reference values ready, reducing the need for frequent re-transmissions and minimizing error propagation while maintaining synchronization accuracy.
2Productivity
If transmission power is increased to improve data rate, then data throughput is improved, but uplink noise management deteriorates
Solution Approach 1:
The patent implements feedback mechanisms where the base station continuously monitors uplink noise levels and channel conditions, then sends differential rate correction commands to the UE. The UE adjusts its transmission rate based on this feedback, allowing dynamic optimization of throughput while preventing excessive noise generation. The closed-loop control ensures the system adapts to changing conditions without manual intervention.
3Reliability
If rate control commands are transmitted with high reliability to avoid synchronization loss, then synchronization stability is improved, but transmission resource consumption increases
Solution Approach 1:
The patent changes the parameter of rate control signaling from absolute rate commands to differential rate corrections. This parameter transformation reduces the number of bits required for transmission while maintaining synchronization stability. The differential approach exploits the fact that rate changes are typically small and incremental, allowing compact representation that conserves transmission resources without sacrificing reliability.
Data Source
AI summary
Base stations control the transmission rate that is used by UE (user equipment) to forward them information. A UE periodically forwards a rate request to a base station if the UE needs to have its data transmission rate to the base station increased or decreased, and the base station responds with a rate command. An error can occur in the transmission of the rate command, such that a rate Rnb transmitted by the base station and detected by the UE as Rue may not match. Various schemes are proposed for reducing and correcting such transmission errors. A first scheme involves periodically resetting the transmission rate of the base station and UE with a reference rate. Second to fourth schemes involve periodically comparing the transmission rates of the base station and UE, and replacing the rate of the UE if they differ. A fifth scheme involves a filtering of the feedback command in order to reduce the impact of error propagation. A sixth scheme, which may be used separately or in conjunction with any of the foregoing schemes, involves adjusting a power offset with a repetition factor. All of the schemes are modified during a soft handover of the UE from the base station to a new base station.