Sub-Band Full Duplex Random Access for Low-Latency Uplink
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Solution Overview
Problem
TDD systems in wireless communication face challenges with reduced coverage, increased latency, and reduced capacity due to limited uplink time duration, which can be addressed by implementing sub-band full duplex (SBFD) to enable simultaneous downlink and uplink operations.
Innovation Solution
A method and apparatus support sub-band full duplex by configuring frequency and time resources for SBFD through system information, allowing terminals to perform random access procedures and PUSCH transmission in specific frequency regions, thereby enabling simultaneous downlink and uplink operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If TDD time domain resource is split between downlink and uplink, then downlink and uplink can be separated in time, but uplink coverage is reduced, latency increases and capacity is reduced
Solution Approach 1:
The patent transitions from time-domain separation (TDD) to frequency-domain separation (FDX) by introducing sub-band full duplex operation. Downlink and uplink are separated in frequency instead of time, allowing simultaneous transmission in different frequency regions, thereby eliminating uplink latency and capacity limitations imposed by time division.
Solution Approach 2:
The patent divides the frequency band into multiple sub-bands, with specific sub-bands allocated for downlink and uplink transmissions simultaneously. This segmentation in the frequency domain enables full duplex operation by separating transmit and receive frequencies, resolving the capacity and latency trade-off in TDD systems.
2Productivity
If TDD time domain resource is split between downlink and uplink, then downlink and uplink can be separated in time, but uplink coverage is reduced
Solution Approach 1:
The patent transitions from time-domain separation (TDD) to frequency-domain separation (FDX) by introducing sub-band full duplex operation. Downlink and uplink are separated in frequency instead of time, allowing simultaneous transmission in different frequency regions, thereby eliminating uplink latency and capacity limitations imposed by time division.
Solution Approach 2:
The patent changes the operational parameter from time-division to frequency-division by configuring specific frequency regions for uplink and downlink. This parameter change enables simultaneous transmission with extended coverage by utilizing available frequency resources that would otherwise be idle in TDD systems.
3Productivity
If sub-band full duplex is implemented with frequency region configuration, then simultaneous downlink and uplink transmission is enabled, but system complexity increases
Solution Approach 1:
The system configures frequency regions and random access parameters through broadcast system information, allowing terminals to autonomously determine appropriate frequency regions for preamble transmission and response reception without complex centralized scheduling. This self-service approach reduces control signaling overhead and simplifies resource management despite the frequency-domain separation.
4Reliability
If random access procedure is configured for SBFD with specific frequency regions, then proper resource allocation is achieved, but configuration complexity increases
Solution Approach 1:
The patent extends the existing random access procedure framework to support both TDD and FDX modes by introducing frequency region indicators and conditional parameter selection. The same random access mechanism serves multiple purposes (initial access, handover, uplink synchronization) across different duplexing modes, reducing the need for separate specialized procedures and minimizing configuration complexity.
Data Source
AI summary
A method and apparatus to support sub-band full duplex is provided. In the method, the terminal receives from a base station a system information; the terminal triggers a random access for a specific feature or based on PDCCH order; the terminal determines frequency region for preamble transmission; the terminal transmits a preamble in the frequency region; the terminal receives a random access response in a specific frequency region; and the terminal performs PUSCH transmission based on the random access response.