Terminal Random Access in Unlicensed Bands via Channel Sensing
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Solution Overview
Problem
Current wireless communication systems, particularly 5G networks, face challenges in efficiently providing services due to issues with random access procedures, especially in scenarios where multiple terminals contend for resources in unlicensed bands, leading to potential collisions and unsolvable in-device coexistence problems.
Innovation Solution
The implementation of a method where terminals detect and report unsolvable in-device coexistence issues related to NR-unlicensed bands, using channel sensing and Listen-Before-Talk techniques to manage resource occupancy, and transmitting capability information to the network to inform about NR-U or LAA support, enabling effective coexistence with other wireless technologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If terminals transmit random access preambles in unlicensed bands without channel sensing, then random access speed is improved, but collision probability increases and in-device coexistence problems occur
Solution Approach 1:
The terminal performs channel sensing (Listen-Before-Talk) before transmitting the random access preamble in the unlicensed band. This preliminary action of detecting channel availability prevents collisions with other transmissions and resolves the in-device coexistence problem by ensuring the channel is clear before access, thereby maintaining reliability while enabling random access in unlicensed spectra.
2Reliability
If terminals use channel sensing and Listen-Before-Talk techniques, then collision prevention is improved, but access delay increases
Solution Approach 1:
The terminal performs channel sensing for a limited duration (e.g., 25 microseconds) before attempting random access. This partial action approach balances collision prevention with access speed by sensing only long enough to detect obvious collisions, rather than performing exhaustive channel assessment. The terminal can proceed with access if the channel appears clear, reducing unnecessary delay while still preventing major collisions.
3Productivity
If terminals report NR-U capability information to the network, then network resource allocation efficiency is improved, but signaling overhead increases
Solution Approach 1:
The terminal extracts and reports only the essential NR-U capability information (support for unlicensed band operation, Listen-Before-Talk capability, and in-device coexistence issue detection) to the network. By taking out only the critical capability parameters needed for efficient resource allocation in unlicensed bands, the signaling overhead is minimized while still enabling the network to optimize resource allocation for NR-U operations.
Data Source
AI summary
Provided are a method and apparatus for transmitting and receiving data in a wireless communication system. A method of performing, by a terminal, random access includes: obtaining physical random access channel (PRACH) resource allocation information for the random access; transmitting a random access preamble, based on the PRACH resource allocation information; receiving a random access response (RAR) based on the random access preamble; and transmitting Msg3, which is a radio resource control (RRC) layer message, a plurality of times based on uplink resource allocation information included in the RAR.