Inter-gNB Xn Signaling for NR TDD Slot Format Configuration
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Solution Overview
Problem
Existing technologies face challenges in efficiently signaling used radio frame configurations between two gNBs over the Xn interface, particularly in 5G NR TDD mode, which requires a scalable solution to cover static, semi-static, and dynamic TDD operations, and also need to account for cross-link interference sensitivity.
Innovation Solution
The proposed solution involves preparing and signaling supported slot format information as a list and used radio frame configuration information as a vector, along with cross-link interference sensitivity information, using the Xn interface, allowing for efficient and scalable inter-gNB signaling. This includes quantizing cross-link interference sensitivity to reduce overhead and applying appropriate slot formats based on sensitivity levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If detailed radio frame configuration information is signaled between gNBs, then the accuracy and completeness of TDD operation coordination is improved, but the signaling overhead increases
Solution Approach 1:
The radio frame configuration is segmented into individual slot format indicators, where each slot can be independently configured. Instead of signaling the entire frame structure as a single unit, the system divides it into M slots, with each slot represented by an index pointing to a predefined slot format in a supported slot format list. This segmentation reduces the overall signaling overhead while maintaining the ability to precisely control each slot's configuration.
Solution Approach 2:
The system pre-defines a list of supported slot formats at the gNB, which are agreed upon in advance through capability exchange. These predefined formats serve as a reference table, allowing subsequent configuration signaling to simply reference indices rather than transmitting complete configuration details. This preliminary action significantly reduces the amount of data that needs to be signaled for each radio frame configuration update.
2Reliability
If cross-link interference sensitivity information is included in signaling, then the ability to manage interference is improved, but the complexity of the signaling protocol increases
Solution Approach 1:
Cross-link interference sensitivity information is provided on a per-slot basis rather than as a global parameter. Each slot in the radio frame can have its own sensitivity indicator, allowing the system to differentiate between slots that are sensitive to interference and those that are not. This localized approach enables targeted interference management without requiring complex global coordination mechanisms.
Solution Approach 2:
The system introduces additional parameters (slot format indices and interference sensitivity indicators) to the existing signaling framework. By changing the parameter structure to include these elements, the system enhances interference management capabilities while maintaining compatibility with the existing TDD operation signaling mechanisms. The parameters are integrated into the same signaling message structure, avoiding the need for separate complex protocols.
3Adaptability or versatility
If the system supports both static and dynamic TDD operations, then the versatility of the solution is improved, but the device complexity increases
Solution Approach 1:
The system enables dynamic TDD operation by allowing the slot format configuration to change over time through updates to the supported slot format list and the radio frame configuration indicators. The same signaling mechanism that supports static configurations can also dynamically reconfigure slots between different formats, including switching between uplink and downlink directions. This dynamic capability is achieved through periodic or event-triggered updates of the configuration parameters without requiring separate protocol paths for static and dynamic operations.
Data Source
AI summary
A method and an apparatus are described, by which a supported slot format information concerning radio frame configuration is prepared in form of a list in which supported slot formats for time division duplexing are listed, the supported slot format information is signaled to a network control device, used radio frame configuration information is prepared in form of a vector which has a length M which is the number of slots, wherein an i-th element of the vector indicates the used slot format in the i-th slot by a number indicating an entry in the list of the supported slot format information, wherein 1<=i<=M, and the used radio frame configuration information is signaled to the network control device.