Transmit Diversity Feedback During Soft Handoff Beamforming
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Solution Overview
Problem
In wireless communications, mobile transmit diversity devices face suboptimal performance during soft handoff situations due to interference from signals propagating along different paths, leading to destructive interference and inefficient beam-forming between multiple base stations.
Innovation Solution
The system improves transmit diversity by using feedback from multiple base stations to adjust transmit diversity parameters, such as phase difference and power ratio, to focus beam-forming effectively at multiple receivers, employing a power control signal as a quality indicator and perturbing signals to optimize signal quality based on feedback from multiple sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single beam is formed toward multiple receivers during soft handoff, then coverage area is expanded, but signal quality deteriorates due to destructive interference
Solution Approach 1:
The patent segments the transmit beam into multiple independent beams, each directed toward a specific receiver. Instead of forming a single beam that attempts to cover multiple receivers simultaneously, the system creates separate beam paths that can be independently optimized for each receiver's location and channel conditions.
Solution Approach 2:
The patent applies local quality by optimizing beam characteristics specifically for each receiver's location. Each beam is tailored with appropriate phase, amplitude, and directional properties suited to its target receiver, rather than using a uniform beam configuration that compromises performance for all receivers.
2Reliability
If transmit diversity parameters are adjusted for one receiver, then signal quality for that receiver improves, but signal quality for other receivers deteriorates
Solution Approach 1:
The patent implements dynamic beam management where transmit diversity parameters are continuously adjusted based on real-time feedback from multiple receivers. The system can dynamically switch between different beam configurations and parameter settings to optimize performance for different receiver conditions without manual intervention.
Solution Approach 2:
The patent employs feedback mechanisms where receivers provide quality measurements back to the transmitter. This feedback loop enables the transmitter to adjust beam parameters adaptively, balancing the needs of multiple receivers by incorporating their performance feedback into the parameter optimization process.
3Productivity
If multiple antenna elements are used to serve more users, then spectral efficiency improves, but signal interference increases due to different propagation paths
Solution Approach 1:
The patent applies local quality by optimizing the transmit signal characteristics for each specific receiver's propagation path. Each antenna element's signal is adjusted with receiver-specific phase and amplitude settings that account for the unique path characteristics, reducing destructive interference while maintaining spectral efficiency.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting phase differences, power ratios, and beam directions based on receiver conditions. These parameter modifications allow the system to adapt to different propagation paths and reduce interference while maintaining high spectral efficiency for multiple users.
Data Source
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 within the range of at least two receivers. In such situations, the transmitter may use the power control signals from more than one receiver, for example, from the two most dominant receivers in order to focus the beamforming accordingly.