Two-Step Random Access Method with Preamble-PUSCH Mapping
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Solution Overview
Problem
The existing four-step random access procedure in wireless communication systems incurs high latency and signaling overheads, particularly for ultra-reliable and low-latency communications (URLLC) and massive machine-type communications (mMTC) services, due to conflicts between user equipment (UE) and interference, which is not adequately addressed in current two-step procedures regarding resource selection for uplink data transmission.
Innovation Solution
A method where a terminal receives configuration information from a network device to determine a physical random access channel (PRACH) time-frequency resource and a corresponding physical uplink shared channel (PUSCH) time-frequency resource, allowing direct transmission of uplink data with reduced latency and signaling overheads by associating each preamble sequence with a PUSCH time-frequency resource.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a four-step random access procedure is used, then the connection establishment between UE and BS is reliable, but the transmission latency is high and signaling overheads are high
Solution Approach 1:
The patent combines the random access preamble transmission and uplink data transmission into a single message (MsgA) that is sent simultaneously. This merging of operations reduces the number of sequential steps from four to two, thereby reducing transmission latency while maintaining connection establishment reliability through the inclusion of uplink data in the initial access message.
Solution Approach 2:
The patent enables the UE to transmit uplink data in advance during the random access procedure itself, before completing full uplink synchronization. By performing the data transmission action preliminarily in MsgA, the system reduces the overall latency without sacrificing the reliability of subsequent communication, as the data is sent before the UE fully transitions to connected state.
2Reliability
If a four-step random access procedure is used, then the connection establishment is reliable, but the signaling overheads are high
Solution Approach 1:
The patent merges multiple signaling messages into a single MsgA that contains both the random access preamble and the uplink data. This consolidation reduces the total number of signaling exchanges between UE and BS, thereby reducing signaling overheads while maintaining reliable connection establishment through the integrated message structure.
Solution Approach 2:
The patent extracts the uplink data transmission opportunity from the post-synchronization phase and incorporates it into the random access phase. By taking out the data transmission step and placing it in MsgA, the system eliminates unnecessary subsequent signaling messages, reducing overall signaling overheads while preserving connection reliability.
3Loss of time
If a two-step random access procedure is used, then the transmission latency is reduced, but the resource selection for uplink data transmission is not properly solved
Solution Approach 1:
The patent performs preliminary configuration of the mapping relationship between PRACH time-frequency resources and PUSCH time-frequency resources before the random access procedure. This preliminary setup includes configuring the correspondence between preamble sequences and PUSCH resources, which simplifies the resource selection process during actual transmission by eliminating the need for complex real-time decisions.
Solution Approach 2:
The patent introduces configuration information as an intermediary that bridges the PRACH resource selection and PUSCH resource allocation. This configuration information, which includes the mapping relationship and preamble-PUSCH correspondence, acts as a mediator that simplifies the UE's operation by providing pre-determined resource assignments based on the selected preamble, thereby reducing operational complexity while maintaining low latency.
Data Source
AI summary
A random access method, a device, and a system are provided, related to the field of communications technologies. The method includes: receiving first configuration information, second configuration information, and third configuration information that are sent by a network device, wherein the first configuration information is used to configure a PRACH time-frequency resource and a preamble sequence set, the second configuration information is used to configure a PUSCH time-frequency resource block corresponding to each PRACH time-frequency resource, and the third configuration information is used to configure a size of each PUSCH time-frequency resource and a correspondence between a preamble sequence and a PUSCH time-frequency resource; and sending a first message including a first preamble sequence and uplink data, wherein the first preamble sequence is carried on a first PRACH time-frequency resource, and the uplink data is carried on a PUSCH time-frequency resource associated with the first PRACH time-frequency resource.