5G Random Access Response Handling for Contention Resolution
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Solution Overview
Problem
The existing random access processes in new generation radio communication systems, such as 5G, face challenges in designing an effective random access response mechanism that accommodates the unique requirements of these systems, particularly in handling UE identifiers and contention resolution across different access scenarios.
Innovation Solution
A method and device for responding to random access in 5G systems, where the UE sends a random access request with or without a UE identifier, and the network side adaptively generates a random access response, using MAC PDU with MAC RARs that include UE identifiers or not, depending on the request, to facilitate two-step or four-step random access processes, ensuring correct feedback and contention resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a two-step random access process is implemented to reduce access latency, then the random access speed is improved, but the complexity of handling different random access types (two-step and four-step) increases
Solution Approach 1:
The random access response message is designed to serve multiple functions: it can handle both two-step and four-step random access scenarios, provide timing advance commands, allocate uplink resources, and perform contention resolution. By making the response message universal and multi-functional, the system reduces access latency through two-step RA while managing the complexity of supporting multiple access types through a unified response mechanism.
Solution Approach 2:
The random access response message structure is made dynamic and adaptive. The network can selectively include or exclude certain fields (such as contention resolution identity, uplink grant, timing advance) based on the specific random access type and scenario. This dynamic configuration allows the system to optimize for speed in two-step RA while maintaining compatibility with four-step RA, effectively resolving the contradiction between speed improvement and handling complexity.
2Reliability
If UE identifier is always included in random access response for contention resolution, then the reliability of contention resolution is improved, but the message length and processing overhead increase
Solution Approach 1:
Instead of uniformly including UE identifier in all random access responses, the patent applies local quality by selectively including the contention resolution identity field only when necessary. For two-step random access where contention resolution is needed, the UE identifier is included. For four-step random access or scenarios where contention resolution is handled differently, the field may be omitted or handled separately. This selective approach maintains reliability where needed while reducing overall message overhead.
Solution Approach 2:
The patent changes the parameter of message structure dynamically based on the random access type and contention resolution requirements. The inclusion of UE identifier becomes a variable parameter rather than a fixed element. This allows the system to adjust the message composition to match the specific scenario, ensuring reliable contention resolution when required while minimizing processing overhead in scenarios where it is not needed.
3Adaptability or versatility
If adaptive random access response generation is implemented to handle different scenarios, then the adaptability of the system is improved, but the complexity of response message generation increases
Solution Approach 1:
The patent applies preliminary action by pre-defining multiple standardized response message formats (such as formats with and without contention resolution identity, with and without uplink grant). These pre-configured templates allow the network to quickly select and populate the appropriate format based on the detected random access type, rather than generating a completely custom message each time. This reduces the complexity of adaptive response generation while maintaining high adaptability to different scenarios.
Solution Approach 2:
The random access response message is segmented into distinct functional components or fields (contention resolution identity, timing advance command, uplink grant, C-RNTI). Each segment can be independently configured, included, or excluded based on the specific random access scenario. This segmentation allows the network to build adaptive responses by selectively combining predefined segments, reducing the overall complexity of message generation while maintaining versatility across different access types.
Data Source
AI summary
The present disclosure relates to a method and a device for responding to a random access. The method includes: a user equipment (UE) sending a random access request, wherein information including a UE identifier is carried in the random access request; and the UE receiving a random access response, wherein when UE identifier carried in the random access response is consistent with the UE identifier in the random access request, a contention resolution is completed; when the UE identifier carried in the random access response is inconsistent with the UE identifier in the random access request, the UE determines that the random access fails this time, and re-initiates a random access attempt; and when no UE identifier is carried in the random access response, the UE falls back to a random access process in which no UE identifier information is carried in the random access request.