Uplink Transmit Diversity Antenna Weight Control
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Solution Overview
Problem
Uplink transmit diversity in wireless communications leads to abrupt changes in antenna weights, causing inaccurate channel estimates and increased interference, which reduces receiver performance and affects power control, especially in scenarios where UEs constantly change their antenna weights or are close to the cell border, leading to overall system performance degradation.
Innovation Solution
A method for a wireless access network node to control user equipment (UE) antenna weights through control signals, allowing autonomous selection of antenna weights without requiring a dynamic feedback channel, enabling the network to decide when UEs should use uplink transmit diversity, thereby reducing interference and improving channel estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If UEs autonomously select antenna weights based on existing feedback channels, then a new feedback channel is not required, but channel estimation accuracy deteriorates due to abrupt weight changes
Solution Approach 1:
The network node sends control signals to the UE in advance to indicate when antenna weight changes are permitted. The UE then performs autonomous antenna weight selection only during these predetermined time instances, rather than changing weights continuously or autonomously at any time. This preliminary scheduling of weight change opportunities resolves the contradiction by maintaining feedback channel simplicity while ensuring channel estimates remain accurate between scheduled changes.
2Productivity
If UEs frequently change antenna weights to optimize transmit diversity, then uplink performance is improved, but interference variations increase causing flash light effects
Solution Approach 1:
The system implements periodic action by restricting antenna weight changes to specific, predetermined time instances scheduled by the network node. Instead of continuous or frequent weight changes, the UE updates antenna weights only at these periodic opportunities. This resolves the contradiction by maintaining uplink performance optimization while reducing interference variations to acceptable levels through controlled, periodic updates rather than continuous changes.
3Device complexity
If UEs use switched antenna diversity with single power amplifier, then device complexity is reduced, but transmit power continuity deteriorates causing power control issues
Solution Approach 1:
The network node provides preliminary control signals to the UE indicating predetermined time instances when antenna switching is permitted. The UE switches antennas only at these scheduled moments rather than dynamically whenever channel conditions change. This preliminary scheduling resolves the contradiction by maintaining the simple single power amplifier configuration while ensuring transmit power remains stable through controlled, scheduled antenna transitions rather than uncoordinated switching.
Data Source
AI summary
The present disclosure discloses a method in a wireless access network node for controlling a UE. The UE comprises at least two transmit antennas, and is capable of uplink transmit diversity. There is an antenna weight associated with each transmit antenna. First, the wireless access network node determines that the antenna weights of the user equipment may be controlled. Then, it creates a control signal that comprises control information and transmits it to the user equipment. The control information controls a UE autonomous selection of the antenna weights in the UE.