Coherent Transmission Phase Stability in TDD Wireless Networks
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Solution Overview
Problem
In wireless communication, especially in TDD networks, maintaining coherent transmission between uplink and downlink transmissions is challenging due to phase drift issues, which complicates joint channel estimation and reduces the effectiveness of coherent transmission, particularly in scenarios with heavy UL/DL switching and weak coverage areas.
Innovation Solution
The solution involves a method where a UE transmits an indication of its requirements for supporting coherent transmission to an access node, allowing the access node to configure radio settings for a specific coherent transmission time period, enabling separate antenna configurations for UL and DL communications to maintain constant load impedance and phase stability during switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If heavy UL/DL switching is performed in TDD networks, then communication flexibility is improved, but phase continuity deteriorates making coherent transmission difficult
Solution Approach 1:
The UE transmits an indication of its coherent transmission requirements to the access node before the actual transmission occurs. The access node then configures radio parameters (such as subcarrier spacing, cyclic prefix length, and resource allocation) in advance to ensure phase continuity is maintained during UL/DL switching, preventing phase drift before it can occur.
Solution Approach 2:
The system dynamically adjusts radio configuration parameters based on the UE's coherent transmission requirements and the specific UL/DL switching pattern. The access node modifies subcarrier spacing, cyclic prefix configuration, and resource allocation dynamically to maintain phase continuity while accommodating flexible UL/DL switching scenarios.
2Measurement precision
If joint channel estimation is performed across multiple transmission occasions, then channel estimation accuracy is improved, but transmission parameter stability requirements increase
Solution Approach 1:
The invention changes key transmission parameters (subcarrier spacing, cyclic prefix length, resource allocation) to values that are optimized for coherent transmission. By selecting specific parameter combinations that maintain phase continuity and satisfy coherent transmission requirements, the system enables accurate joint channel estimation while managing the complexity of parameter stability control through standardized parameter sets.
3Measurement precision
If coherent transmission is maintained during UL/DL switching, then joint channel estimation performance is improved, but UL coverage in weak coverage areas deteriorates
Solution Approach 1:
The system applies different configuration strategies to different parts of the transmission. For reference signal transmissions where coherent transmission is critical, specific radio parameters are configured to maintain phase continuity. For data transmissions in weak coverage areas, the system allows more flexible parameter adjustment to ensure reliable reception, applying local optimization rather than uniform constraints across all transmissions.
Data Source
AI summary
A method carried out in a User Equipment, UE, for facilitating communication with an access node of a wireless network using coherent transmission, CT, the method comprising: transmitting, to the access node, an indication of requirements of the UE for supporting CT associated with switching between Uplink, U L, and Downlink, DL; obtaining, from the access node, radio configuration for transmitting to the access node based on said requirements for supporting CT, wherein said radio configuration is associated with a certain CT time period.