TDD Radio Filtering with Separate Tx and Rx Signal Paths
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Solution Overview
Problem
In Time Division Duplexing (TDD) radio communication systems, the use of a shared filter for both transmitting and receiving signals leads to increased filter insertion loss and performance degradation due to differing filtering requirements, necessitating excessive out-of-band attenuations.
Innovation Solution
A radio network entity comprising three separate filters: a first filter for common filtering requirements, a second filter for additional filtering on the transmitting path, and a third filter for additional filtering on the receiving path, with distinct frequency attenuations to meet specific requirements for each path, allowing for improved filtering performance and reduced power handling needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a UE transmits SRS in both uplink slots of a TDD frame structure, then channel quality for both directions can be measured, but uplink-downlink allocation flexibility is reduced and control signaling overhead increases
Solution Approach 1:
The patent extracts the channel quality measurement function from the SRS transmission and implements it through a separate sounding reference signal. This allows the main uplink data transmission to proceed without being burdened by the measurement overhead, as the channel quality can be derived from the dedicated SRS transmissions in specific slots.
Solution Approach 2:
The patent introduces a channel quality indicator (CQI) as an intermediary that translates channel conditions into actionable information for resource allocation. The CQI is calculated based on SRS measurements and transmitted to the base station, serving as a mediator between the physical channel state and the logical resource allocation decisions.
2Productivity
If TDD frame structure is used to share spectrum between uplink and downlink, then spectrum utilization efficiency is improved, but uplink-downlink allocation flexibility is reduced when slot formats are predetermined
Solution Approach 1:
The patent implements dynamic slot format indication where the slot format is not fixed but can be changed based on real-time traffic conditions. The base station can dynamically adjust the uplink-downlink slot allocation by transmitting slot format indicators, allowing the system to adapt to varying traffic demands while maintaining TDD spectrum sharing efficiency.
Solution Approach 2:
The patent uses preliminary channel quality measurements through SRS transmissions to predict future channel conditions and proactively adjust slot formats before traffic demands change. This allows the system to prepare optimal uplink-downlink allocations in advance based on measured channel characteristics, improving both spectrum utilization and flexibility.
Data Source
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AI summary
Embodiments provides a radio network entity and the method thereof for improving filtering performance in a time division duplexing radio communication system, the radio network entity comprises: a first filter, which is configured to perform a first type of filtering for a signal to be transmitted to, or received from a device in the radio communication system through a radio interface, with a common filtering requirement for transmitting and receiving fulfilled,a second filter, which is configured to perform a second type of filtering for the signal to be transmitted to the device, with additional filtering requirement for transmitting besides the common filtering requirement fulfilled; and a third filter, which is configured to perform a third type of filtering for the signal received from the device, with additional filtering requirement for receiving besides the common filtering requirement fulfilled.