Enhanced PUSCH Transmission for 5G RACH Latency Reduction
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Solution Overview
Problem
Conventional 2-step RACH procedures in 5G mobile communication systems suffer from significant latency and resource consumption, particularly in time-sensitive applications, due to separate transmissions of PRACH preamble and PUSCH, which hinder efficient user equipment (UE) access to the network.
Innovation Solution
The method involves transmitting an enhanced PUSCH transmission (PUSCH++) that combines a DMRS part and a PUSCH data part in a single transmission, using a long length format similar to the long length PRACH format, where the DMRS part serves as a preamble for synchronization and user identification, and the PUSCH data part carries user-plane data, with configurable lengths and power levels to optimize UE detection and data decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If separate transmissions of PRACH preamble and PUSCH are used in conventional 2-step RACH procedures, then user separation and signal distinction are achieved, but significant latency and resource consumption occur
Solution Approach 1:
The patent combines the PRACH preamble transmission and PUSCH data transmission into a single unified transmission structure. The PUSCH transmission incorporates both the DMRS (demodulation reference signal) that serves as the preamble and the uplink data payload in one continuous transmission, eliminating the time gap and separate processing required in conventional approaches. This merging directly reduces RACH procedure latency while maintaining the functional separation needed for user identification and data transmission.
Solution Approach 2:
The PUSCH transmission structure is designed to serve multiple functions simultaneously: the DMRS portion provides preamble functionality for user equipment identification and synchronization, while the remaining portion carries uplink data payload. This multi-functional design allows a single transmission to replace what previously required separate preamble and data transmissions, reducing overall procedure time and resource consumption while maintaining the ability to distinguish different users through their unique DMRS sequences.
2Measurement precision
If long length PRACH format is used for enhanced PUSCH transmission, then synchronization accuracy and user identification are improved, but transmission time and resource consumption increase
Solution Approach 1:
The transmission is segmented into two functional portions within a single continuous transmission: the DMRS (demodulation reference signal) portion and the PUSCH data payload portion. The DMRS portion uses the long length format characteristics (extended cyclic prefix, specific sequence length) to provide accurate synchronization and user identification, while the data payload portion can be optimized for efficient data transmission. This segmentation allows the system to benefit from the robust synchronization properties of long format without requiring the entire transmission to be extended.
Solution Approach 2:
The patent applies parameter changes by configuring the DMRS with specific long format characteristics (extended cyclic prefix length, specific sequence length) only for the reference signal portion, while the accompanying data payload can use more efficient parameters. This selective application of long format parameters to only where needed (synchronization and identification) maintains measurement precision while minimizing the overall transmission time impact.
Data Source
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AI summary
There is provided a method of performing a RACH procedure to provide a User Equipment UE access to a network (3) in a communication system (100), the network comprising at least one base station (2), the RACH procedure comprising at least one step in which a RACH message is sent from the UE to the base station on one or more uplink channels. The message comprises an enhanced PUSCH transmission (PUSCH++) comprising a DMRS part and a PUSCH data part, the DMRS part being sent as a preamble. The method comprises transmitting the DMRS part and the PUSCH data part together in a single transmission, the enhanced PUSCH having a long length format that is the same format as a long length PRACH format or a format similar to the long length PRACH format.