Two-Step Random Access with Preamble-Linked Uplink Resources
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Solution Overview
Problem
Existing wireless communication systems face latency issues during the random access procedure, which are not sufficient for faster and newer communications in 4G and 5G networks.
Innovation Solution
A method involving the mapping of preamble indexes to multiple resources, such as PRACH and PUSCH occasions, to reduce signal overhead and enhance synchronization efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a traditional 4-step random access procedure is used, then the UE can obtain uplink and downlink synchronization with the BS, but the procedure induces latency and cannot meet the needs of faster communications
Solution Approach 1:
The patent combines Message 1 (preamble) and Message 3 (data transmission) into a single uplink transmission, and combines Message 2 (random access response) and Message 4 (contention resolution) into a single downlink transmission. This merging reduces the number of interaction steps from 4 to 2, thereby reducing access latency and improving access speed while maintaining synchronization functionality.
2Productivity
If preamble indexes are mapped to multiple resources, then resource allocation efficiency is improved, but the device complexity increases
Solution Approach 1:
The patent enables the UE to self-determine the uplink resource for Message 3 by autonomously mapping the preamble index to the corresponding resource based on pre-configured mapping relationships. This self-service approach eliminates the need for additional downlink signaling to indicate resource allocation, thereby improving resource allocation efficiency while the standardized mapping rules keep the implementation complexity manageable.
Data Source
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AI summary
Method, systems and devices for a random access procedure, performed by a network device, are provided. The method included selecting one of a plurality of preamble indexes of a first resource, and at least one set of the plurality of preamble indexes is mapped to at least one second resource based on a first number of the at least one set of the plurality of preamble indexes and a second number of the at least one second resource; transmitting, to a network node, a first message including a preamble at the selected preamble index of the first resource and a payload in the second resource associated to the selected preamble index; and receiving, from the network node, a second message in response to a first message.