PRACH Small Data Transmission Without RRC Connection Setup
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Solution Overview
Problem
Existing wireless communication systems face limitations in efficiently transmitting small data packets during the RRC idle state, particularly in LTE and NR systems, due to restrictions on the number of protocol data units (PDUs) that can be transmitted, which hampers flexibility in IoT applications.
Innovation Solution
A method for small data transmission (SDT) during the random access procedure, involving the use of differentiated PRACH resource configurations for 2-step and 4-step RACH processes, allowing for the transmission of small data payloads in PRACH uplink messages, and subsequent contention resolution messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If EDT is used for small data transmission during RRC idle state, then power consumption is reduced, but data transmission flexibility is limited due to only one PDU being allowed
Solution Approach 1:
The patent segments the random access procedure into multiple steps (4-step RACH: Msg1, Msg2, Msg3, Msg4; or 2-step RACH: MsgA, MsgB), allowing data transmission to be distributed across different messages. This enables flexible data payload sizes by combining small data with control information in multiple transmission stages, resolving the contradiction between low power consumption and transmission flexibility.
Solution Approach 2:
The patent introduces dynamic selection between different random access procedures (4-step vs 2-step RACH) and different message formats (Msg3 vs MsgA for data transmission). This dynamic adaptability allows the system to adjust the transmission method based on data size and network conditions, maintaining flexibility while keeping the UE in RRC idle state to save power.
2Adaptability or versatility
If UE enters RRC connected state for data transmission, then data transmission flexibility is improved, but power consumption increases
Solution Approach 1:
The patent performs preliminary data transmission during the random access procedure itself (in Msg3 or MsgA) before the UE needs to transition to RRC connected state. By embedding data payloads in the random access messages, the system achieves flexible data transmission while keeping the UE in the lower-power idle state, avoiding the power consumption penalty of connection establishment.
Solution Approach 2:
The patent makes the random access procedure serve multiple functions: both establishing connectivity and transmitting data simultaneously. The PRACH resources are designed to carry both random access preambles and data payloads, creating a multi-functional mechanism that achieves flexible data transmission without requiring full connection establishment.
3Adaptability or versatility
If differentiated PRACH resource configuration is used for SDT, then data transmission flexibility is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by configuring specific PRACH resources (dedicated preambles, specific time-frequency resources) exclusively for small data transmission purposes. This localized differentiation within the overall PRACH structure enables flexible SDT without requiring complete redesign of the random access system, thus limiting the increase in device complexity to specific localized configurations.
Data Source
AI summary
A user equipment (UE) executes a small data transmission method. The UE obtains small data transmission (SDT) physical random access channel (PRACH) resource configuration for small data transmission. The SDT PRACH resource configuration comprises at least one of a first random access preamble or a first set of radio resources for transmission of the first random access preamble and is differentiated from non-SDT PRACH resource configuration. The UE initiates a random access procedure by transmitting the first random access preamble on the first set of radio resources for the SDT. The small data transmission includes transmission of a first data payload in a PRACH uplink message of the random access procedure.