Two-Step Random Access Response Signaling for Reduced Access Delay
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Solution Overview
Problem
Existing random access procedures in multicarrier communication systems face inefficiencies and challenges in managing contention resolution and resource allocation, particularly in scenarios involving multiple carriers and varying numerologies.
Innovation Solution
A two-step random access procedure is introduced, where a base station receives a first message with a contention resolution identifier and responds with a slot offset and start symbol, followed by a second response from a designated start symbol, optimizing resource allocation and contention resolution through enhanced signaling mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional multi-step random access procedure is used, then contention resolution can be achieved, but access delay and signaling overhead increase
Solution Approach 1:
The random access procedure is divided into two distinct steps: Step 1 where the UE transmits preamble and receives RAR, and Step 2 where the UE transmits MSG3 and receives contention resolution. This segmentation allows optimization of each step independently, reducing overall access delay while maintaining reliable contention resolution.
Solution Approach 2:
The base station performs preliminary actions by pre-configuring RAR windows and contention resolution parameters before the random access procedure begins. This preliminary configuration enables faster processing during the actual access procedure, reducing access delay while ensuring reliable contention resolution.
2Reliability
If a traditional multi-step random access procedure is used, then contention resolution can be achieved, but signaling overhead increases
Solution Approach 1:
The patent combines contention resolution information with uplink data transmission in MSG3. Instead of separate signaling for contention resolution and data transmission, both are merged into a single message, reducing signaling overhead while maintaining reliable contention resolution.
Solution Approach 2:
The MSG3 message serves multiple functions simultaneously: it carries contention resolution information, uplink data, and uplink control information. This multi-functionality reduces the need for separate signaling messages, thereby reducing overall signaling overhead while ensuring reliable contention resolution.
3Productivity
If resource allocation is optimized for multiple carriers, then resource utilization improves, but system complexity increases
Solution Approach 1:
The patent implements dynamic resource allocation across multiple carriers, where the base station can flexibly assign different carriers for different steps of the random access procedure based on current system conditions. This dynamic approach optimizes resource utilization while managing complexity through adaptive rather than static configurations.
Solution Approach 2:
The system changes parameters such as carrier frequency, bandwidth, and numerology based on traffic conditions and system load. By dynamically adjusting these parameters, the system optimizes resource utilization across multiple carriers while managing complexity through parameter optimization rather than structural complexity.
Data Source
AI summary
A base station receives a first message, from a wireless device and for a random access procedure, comprising a contention resolution identifier of the wireless device. The base station transmits, via a first slot indicated by downlink control information (DCI), a first response of the first message, wherein the first response comprises the contention resolution identifier and indicates a slot offset and a start symbol. The base station transmits a second response of the first message from the start symbol of a second slot, wherein the second slot is based on a time offset and the slot offset with respect to the first slot.