Repeated Erasure Indicator Bit Power Control Handoff
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Solution Overview
Problem
In wireless communication systems, power control commands between mobile stations and base stations can be misinterpreted due to fast fading channels, leading to potential termination of wireless phone calls.
Innovation Solution
The method involves using a repeated erasure indicator bit within a frame to indicate power control commands, where the base station adjusts transmit power based on the majority of the erasure indicator bits received, ensuring accurate interpretation and response to power control messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single power control command signal is used in fast fading channels, then the signaling is simple, but the reliability of power control command reception is poor
Solution Approach 1:
The patent combines the power control command signal with the erasure indicator bit that is already being transmitted for error detection purposes. By merging these two functions into a single signaling mechanism, the patent achieves reliable power control command transmission without adding separate dedicated signaling channels, thus maintaining signaling simplicity while improving reliability.
Solution Approach 2:
The erasure indicator bit is given dual functionality: it continues to serve its original purpose of indicating frame erasure errors while simultaneously encoding power control commands. This multi-functionality allows the system to convey both error status and power adjustment instructions through the same signaling resource, resolving the contradiction between reliability and complexity.
2Reliability
If power control commands are transmitted over fast fading channels, then power control is implemented, but misinterpretation of commands occurs leading to call termination
Solution Approach 1:
The patent implements a feedback mechanism where the mobile station monitors the quality of received frames and sends erasure indicator bits back to the base station. This feedback loop allows the base station to adaptively adjust downlink power based on actual channel conditions, improving command accuracy by ensuring power adjustments are made in response to real-time channel quality information.
Solution Approach 2:
The patent changes the interpretation of the erasure indicator bit parameter based on the channel conditions and handoff state. During soft handoff, the erasure indicator bit is reinterpreted to convey power control commands rather than just error status. This parameter reassignment allows the system to overcome fast fading interference by using a parameter whose meaning adapts to the operational context.
Data Source
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AI summary
A wireless communication network (20) includes a power control technique that includes repeating an erasure indicator bit in a transmission from a mobile station (22) to a base station (24, 30, 36). The repeated erasure indicator bit is transmitted on the uplink to each base station. The base station then uses the majority rule of those repeated erasure indicator bits to adjust its transmit power. It results in a desired power control command corresponding to the quality of a downlink between a base station (24, 30, 36) and the mobile station (22). A disclosed example includes using the repeated error indicator bit for deciding whether a recent frame should be considered an erasure. If so, the base station increases power on the downlink forward channel. If not, the base station decreases the transmit power on the downlink forward channel. A disclosed example includes alternative power control adjustment techniques, depending on the recent history of the quality of the downlink.