Reduced Cyclic Prefix Asynchronous Uplink Transmission
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Solution Overview
Problem
The current two-step random access process in wireless communications systems, such as LTE and 5G NR, results in extremely high cyclic prefix (CP) overheads due to the need for asynchronous uplink transmission before uplink synchronization is achieved, leading to increased latency and signaling overheads, especially in ultra-reliable low-latency communications (URLLC) and massive machine-type communications (mMTC) services.
Innovation Solution
Configuring a reduced CP length based on historical timing advance (TA) information of UEs, allowing UEs to determine whether to use the configured CP for asynchronous uplink transmission, ensuring orthogonality between symbols and subcarriers, and potentially omitting the preamble in mMTC scenarios for sporadic small packets, thereby reducing CP overheads and improving resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a CP length same as that of the preamble is used for PUSCH in Msg1, then orthogonality between symbols and subcarriers is ensured, but CP overheads become extremely high
Solution Approach 1:
The patent changes the CP length parameter from being equal to the preamble CP length to being shorter, specifically configured based on historical TA information. This parameter change reduces CP overhead while maintaining acceptable orthogonality through alternative means (timing adjustment based on historical TA).
Solution Approach 2:
The patent uses historical TA information obtained from previous uplink transmissions to pre-configure the CP length and timing parameters for the current Msg1 PUSCH transmission. This preliminary action allows the system to anticipate the required protection length without needing to use the conservative (and excessive) preamble-based CP length.
2Reliability
If four-step random access is used, then uplink synchronization is achieved, but latency and signaling overheads increase
Solution Approach 1:
The patent merges Msg1 and Msg3 into a single transmission step, and merges Msg2 and Msg4 into another single step. This combining eliminates the need for separate random access preamble transmission and data transmission phases, reducing the total number of steps from four to two and thereby reducing latency while maintaining synchronization capability.
Solution Approach 2:
The patent performs preliminary uplink timing adjustment using historical TA information before the actual data transmission in Msg1. This preliminary timing alignment allows the UE to transmit data in the same step as the random access preamble without requiring a separate synchronization phase, thus reducing latency.
3Reliability
If four-step random access is performed for each sporadic small packet transmission, then connection establishment is achieved, but signaling overheads increase
Solution Approach 1:
The patent combines random access signaling and data transmission into a single Msg1 PUSCH transmission. By merging the random access preamble and uplink data into one transmission, the patent eliminates multiple separate signaling exchanges, thereby reducing signaling overhead for sporadic small packet transmissions in mMTC scenarios.
Data Source
AI summary
This application provides an asynchronous uplink transmission method, a device, and a storage medium. The method includes: receiving, by UE, configuration information that is of a first PUSCH and that is sent by a network device, where the configuration information includes a length of a cyclic prefix CP of the first PUSCH, and the length of the CP of the first PUSCH is less than a length of a CP of a first random access preamble; determining, by the UE based on the length of the CP of the first PUSCH, a difference between a largest stored timing advance TA and a smallest stored TA, and a largest delay spread, whether to send the first PUSCH; and if determining to send the first PUSCH, sending, by the UE, the first PUSCH based on the configuration information of the first PUSCH. CP overheads of the UE that meets a condition for using a frame structure of the PUSCH are reduced, and resource utilization is improved.