Two-Step Random Access Method for Unlicensed Spectrum
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Solution Overview
Problem
In new generation mobile communication systems using higher frequency bands, the traditional four-step LTE random access process is inefficient due to high channel occupation ratios in unlicensed spectra, leading to prolonged random access times.
Innovation Solution
A simplified two-step random access method where a network node receives a random access request with a preamble and a data block, and responds with a random access response (RAR), allowing for potential retransmission or contention resolution, thereby reducing delay and improving access success rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the traditional four-step LTE random access process is used in unlicensed spectrum, then the random access procedure follows the standard protocol, but the random access delay becomes excessively long due to high channel occupation ratios requiring multiple listen-before-talk waits
Solution Approach 1:
The patent segments the traditional four-step random access procedure into two distinct phases: a simplified two-step process for initial access attempts, and a fallback four-step process for contention resolution. This segmentation allows the system to bypass multiple LBT waits in the initial access phase while maintaining protocol compliance through the fallback mechanism.
Solution Approach 2:
The patent implements a dynamic random access mechanism that adapts between two different procedures based on channel conditions and access outcomes. The system dynamically switches from the simplified two-step method (when initial access succeeds) to the traditional four-step method (when contention resolution is needed), optimizing performance based on real-time conditions.
2Reliability
If the traditional four-step random access method is used, then the protocol is comprehensive and handles all edge cases, but the implementation complexity increases and the access process becomes too long for small cell networks
Solution Approach 1:
The patent segments the random access functionality into a primary simplified path and a secondary comprehensive path. The two-step method handles the common case with reduced complexity, while the four-step fallback handles edge cases and contention scenarios, allowing the system to achieve completeness without always incurring the full complexity cost.
Solution Approach 2:
The patent extracts the essential random access functionality from the traditional four-step procedure, isolating the core preamble transmission and RAR reception steps into a simplified two-step method. This extraction removes unnecessary intermediate steps for initial access while preserving the ability to handle complex scenarios through the fallback mechanism.
3Reliability
If multiple listen-before-talk waits are performed in the four-step random access process, then channel access compliance is maintained, but the overall access time becomes unacceptably long for high channel occupation ratios
Solution Approach 1:
The patent segments the LBT operations into a minimal required set for the simplified two-step method and the full set for the fallback four-step method. This segmentation reduces the number of LBT waits from multiple sequential operations to a single or reduced number of waits, significantly improving access speed while maintaining compliance through the fallback option.
Solution Approach 2:
The patent performs preliminary channel access compliance checks in the simplified two-step method, establishing a valid access foundation before potentially needing the full four-step procedure. This preliminary action ensures compliance is maintained while avoiding redundant LBT waits that would occur if the full four-step process were always executed.
Data Source
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AI summary
A random access method, device, and equipment. The method comprises: a network node receives a random access request comprising a pilot and a first data block; and the network node transmits a random access response.