Uplink Beamforming Feedback Control in Soft Handoff
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communications, mobile devices with multiple antenna elements face interference issues due to signals propagating along different paths and receiving conflicting feedback from multiple base stations, which complicates the control of transmit diversity parameters, especially in soft handoff situations.
Innovation Solution
A method and system where a mobile communication device adjusts transmit diversity parameters, such as phase difference and power ratio, based on feedback from multiple base stations, using power control signals and dedicated diversity feedback parameters to optimize signal quality, and employs beamforming algorithms to direct signals effectively during soft handoff scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple antenna elements are used to enhance spatial efficiency, then more users can be simultaneously served, but signals propagate along different paths and destructively interfere
Solution Approach 1:
The patent employs feedback mechanisms where base stations send power control signals and quality indication signals back to the mobile device. The mobile device uses this feedback to dynamically adjust its transmit diversity parameters, including phase and power ratio, to optimize signal quality and reduce destructive interference while maintaining spatial efficiency.
Solution Approach 2:
The patent implements dynamic adjustment of transmit diversity parameters based on real-time feedback from multiple base stations. The mobile device continuously modifies phase differences and power ratios between antenna elements according to changing channel conditions, enabling adaptive optimization of spatial efficiency while minimizing signal interference.
2Reliability
If transmit diversity parameters are controlled using feedback from multiple base stations, then signal quality is optimized, but device complexity increases
Solution Approach 1:
The patent extracts and processes only the essential feedback information from multiple base stations, specifically power control signals and quality indication signals. By focusing on these key parameters and using them to control transmit diversity, the system optimizes signal quality while avoiding the complexity of processing all possible feedback parameters from multiple sources.
Solution Approach 2:
The patent uses power control signals, originally designed for power adjustment, as dual-purpose feedback for both power control and transmit diversity parameter control. This multi-functional use of existing feedback mechanisms reduces the need for additional complex control systems while maintaining optimized signal quality.
3Reliability
If power control signals from multiple base stations are used for beamforming, then signal quality improves, but conflicting feedback complicates parameter control
Solution Approach 1:
The patent introduces quality indication signals as intermediary feedback that mediates between conflicting power control signals from multiple base stations. These quality signals provide a unified measure of signal quality that helps resolve conflicts in power control commands, simplifying the control of transmit diversity parameters while maintaining optimized signal quality.
Solution Approach 2:
The patent combines multiple feedback sources (power control signals and quality indication signals) into a unified control mechanism for transmit diversity parameters. By merging these feedback streams and processing them together, the system resolves conflicting information and achieves coordinated control of phase and power ratio parameters across multiple antenna elements.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Embodiments of the present invention describe methods for increasing the amount of information available to a mobile transmit diversity transmitter during soft handoff. According to embodiments of the invention, a transmit diversity transmitter may determine substantially when it is in uplink communication with one base station and downlink communication with another base station. The mobile device may transmitting a diversity signal by controlling a value of a transmit diversity parameter based on feedback signals from the downlink base station, and controlling a power level in accordance with a standard protocol, e.g. combination of transmit power control feedbacks provided by the active base stations.