Antenna Beam Switching for Broadcast Null Elimination
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Solution Overview
Problem
In wireless communication systems, transmitting units with antennas pointing in different directions experience directional nulls when switching to broadcast mode, resulting in inadequate coverage and signal strength variations.
Innovation Solution
Implementing a method that allows instant switching between unicast and broadcast modes using a space-time code (STC) across antennas with partially overlapping beams, enabling a defined beam pattern and near omni-directional coverage by controlling the signal processing unit to apply STC in the broadcast mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If antennas point in different directions for unicast mode, then sector coverage is improved, but broadcast coverage develops directional nulls
Solution Approach 1:
The system dynamically switches between unicast and broadcast modes, and within broadcast mode, dynamically adjusts between different beam patterns (omni-directional and sector-specific) based on service requirements. This dynamic adaptability resolves the contradiction by allowing the antenna system to optimize for sector coverage during unicast mode and for uniform broadcast coverage during broadcast mode.
Solution Approach 2:
The invention changes the radiation pattern parameters of the antenna system based on the transmission mode. In unicast mode, antennas maintain fixed directional patterns for sector coverage. In broadcast mode, the system switches to omni-directional patterns or adjusted beam patterns that eliminate directional nulls, thereby improving broadcast coverage reliability while maintaining sector coverage capability when needed.
2Area of stationary object
If all antennas transmit the same signal in broadcast mode, then coverage area increases, but signal strength varies in overlapping beam areas
Solution Approach 1:
The system applies different signal characteristics to different spatial regions. In broadcast mode, it generates omni-directional signals that provide uniform coverage across all directions, ensuring consistent signal strength in areas where individual antenna beams would otherwise overlap and create variations. This local adaptation of signal quality resolves the contradiction between expanded coverage and signal uniformity.
3Adaptability or versatility
If antennas are used for both unicast and broadcast modes, then system versatility is improved, but mode switching creates coverage inconsistencies
Solution Approach 1:
The system employs dynamic reconfiguration of antenna radiation patterns based on the active transmission mode. When switching from unicast to broadcast mode, the system dynamically adjusts the beam patterns from directional to omni-directional, maintaining coverage stability throughout the transition. This dynamic adaptation allows the system to be versatile across modes while maintaining stable, consistent coverage characteristics within each mode.
Data Source
Figure 1~2a
Figure 2b~2c
Figure 3a~3b
AI summary
The present invention relates to a method and a transmitting unit in a wireless communication system. The transmitting unit is configured to transmit over multiple antennas pointing in different directions. Each antenna provides a beam partially overlapping with at least one other antenna. The method for the transmitting unit comprises switching m time between transmitting (910) in a unicast mode over each of said at least two antennas, and transmitting (920) in a broadcast mode concurrently over all of the at least two antennas using a space time code.