Transmit Diversity via Opportunistic Beamforming
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Solution Overview
Problem
In wireless communication systems, existing methods face challenges in minimizing scheduling latency and channel quality variations, leading to poor service quality and increased delays for mobile nodes, especially in areas with varying channel conditions, and fail to effectively mitigate interference from adjacent cells.
Innovation Solution
The implementation of multiple communication channels with different physical characteristics, allowing wireless terminals to measure and select the best channel based on channel condition feedback, and using opportunistic beamforming to introduce controlled channel variations, which reduces scheduling latency and improves service quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a base station uses a single fixed antenna with a fixed antenna pattern, then the system structure is simple, but the channel quality varies significantly and dead zones are created
Solution Approach 1:
The patent divides the single antenna system into multiple transmit antennas, each capable of transmitting independent signals. This segmentation allows the system to create multiple antenna patterns that can be selectively activated to serve different spatial regions, thereby eliminating dead zones and improving channel quality reliability.
Solution Approach 2:
The patent implements dynamic antenna pattern selection where the base station can switch between different antenna patterns based on mobile node locations and channel conditions. This dynamic adaptation allows the system to maintain reliable channel quality by selecting the most appropriate antenna pattern for each transmission.
2Reliability
If the base station periodically readjusts its antenna pattern to improve channel quality, then channel quality is improved, but scheduling delay increases
Solution Approach 1:
The patent pre-configures multiple antenna patterns in advance, each optimized for different spatial regions or channel conditions. When a mobile node enters a specific region or experiences degraded channel quality, the base station can immediately switch to the pre-configured appropriate antenna pattern without requiring time-consuming readjustment, thereby reducing scheduling delay while maintaining channel quality.
Solution Approach 2:
The patent changes the antenna pattern parameters dynamically based on mobile node location and channel conditions. By having multiple pre-defined antenna patterns with different beam directions and shapes, the system can rapidly switch between patterns to adapt to changing conditions without the delay associated with generating new patterns in real-time.
3Adaptability or versatility
If multiple communication channels with different physical characteristics are implemented, then channel selection flexibility is improved, but device complexity increases
Solution Approach 1:
The patent segments the communication resource into multiple parallel channels, each with distinct physical characteristics such as different antenna patterns, frequencies, or time slots. This segmentation provides channel selection flexibility allowing the system to choose the best channel for each transmission, while the modular structure keeps the complexity manageable through systematic organization.
Data Source
AI summary
Methods and apparatus for providing channel diversity to wireless terminals (WTs) in a manner that reduces the latency between the time a WT encounters satisfactory channel conditions are described. A plurality of communications channels with different physical characteristics are maintained in a cell by a base station (BS). Each WT monitors multiple channels and maintains multiple channel estimates at the same time so that rapid switching between channels is possible. Channel quality information is conveyed from each WT to the BS. The WT or BS selects a channel based on the measured channel quality. By supporting multiple channels and by introducing periodic variations into the channels in various embodiments, the time before a WT encounters a channel with good or acceptable channel conditions is minimized even if the WT does not change location. Multiple antennas are used at the BS to support numerous channels simultaneously, e.g., by controlling antenna patterns.