Two-Step Random Access Using C-RNTI Feedback

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Solution Overview

Problem

Current 5G systems face challenges in two-step contention based random access, particularly in determining successful random access when a UE identifier is carried in the Msg1 message, as existing methods rely heavily on identifying the UE identifier in the RAR MAC PDU.

Innovation Solution

A method and device for two-step contention based random access where a user equipment (UE) sends an Msg1 message carrying a C-RNTI, determining successful access if physical layer scheduling signaling addressed based on the C-RNTI is received, allowing for successful two-step random access.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a UE identifier is carried in the Msg1 message for two-step contention based random access, then the random access process can be completed in two steps, but it becomes difficult to determine successful random access without relying on identifying the UE identifier in the RAR MAC PDU

Engineering Contradiction:

Improverandom access efficiencyVSAvoidsuccessful random access determination

Core Design Contradiction:

ProductivityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent applies feedback by having the network device send scheduling signaling addressed to the C-RNTI carried in Msg1. The UE determines successful random access by receiving this feedback signaling, creating a closed-loop verification mechanism that resolves the difficulty of determining successful access in two-step random access.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent introduces the C-RNTI as an intermediary identifier that bridges the Msg1 transmission and the success determination. By carrying the C-RNTI in Msg1 and using it as the address for scheduling signaling, the system creates a reliable link between the UE's random access attempt and the network's acknowledgment, enabling successful access determination without relying on RAR MAC PDU identification.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If physical layer scheduling signaling addressed based on C-RNTI is used to determine successful access, then the UE can reliably determine successful random access, but the system requires additional signaling overhead

Engineering Contradiction:

Improvesuccessful access determination reliabilityVSAvoidsignaling overhead

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent makes the C-RNTI serve multiple functions: it is carried in the Msg1 for identification purposes and simultaneously used as the address for scheduling signaling. This multi-functionality allows the same identifier to enable both the two-step random access initiation and the successful access determination, reducing the need for additional dedicated signaling overhead.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11470647B2Method and device for two-step contention based random access

Publication Date: 2022.10.11 DATANG MOBILE COMM EQUIP CO LTD

AI summary

A method and a device for two-step contention based random access are provided. The method includes: sending, by a user equipment (UE), an Msg1 message; and determining that two-step random access of the user equipment is successful, in a case that a UE identifier carried in the Msg1 message is a cell radio network temporary identifier (C-RNTI) and physical layer scheduling signaling addressed based on the C-RNTI is received by the user equipment. For two-step contention based random access, if the UE identifier carried in the Msg1 message is a C-RNTI, the user equipment determines that the two-step random access is successful in a case that the physical layer scheduling signaling addressed based on the C-RNTI is received by the user equipment. In this way, the two-step contention based random access can be achieved.