PRACH Small Data Transmission in RRC Idle for Multi-PDU Uplink
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Solution Overview
Problem
Existing wireless communication systems face limitations in flexible small data transmission during the radio resource control idle state, particularly in 3GPP standards Rel-15 and Rel-16, where data sizes larger than 1000 bits require transitioning to an RRC connected state, restricting the flexibility of IoT applications.
Innovation Solution
A method for small data transmission (SDT) involving obtaining and initiating a random access procedure with differentiated PRACH resource configurations for small data transmission, including 2-step and 4-step RACH processes, allowing for the transmission of multiple PDUs without entering an RRC connected state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If EDT is used for small data transmission during RRC idle state, then power consumption is reduced and transmission efficiency is improved, but data size is limited to one PDU (maximum 1000 bits)
Solution Approach 1:
The patent segments the data transmission process into multiple PDUs that can be transmitted sequentially during RRC idle state. Instead of limiting to one PDU as in traditional EDT, the system divides larger data into multiple segments (PDU1, PDU2, etc.) and transmits them using multiple PRACH occasions, allowing IoT applications to send data larger than 1000 bits while remaining in idle state.
Solution Approach 2:
The patent introduces dynamic configuration of PRACH resources for SDT, where the network can configure multiple PRACH occasions with different parameters (preamble formats, frequency resources, time resources) to adapt to varying data sizes and transmission requirements. This dynamic approach allows the system to flexibly handle different data volumes without transitioning to RRC connected state.
2Adaptability or versatility
If UE transitions to RRC connected state for data transmission, then data size limitation is removed, but power consumption increases and transmission delay increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring PRACH resources and parameters for SDT during RRC idle state. The network provides SDT configuration information including multiple PRACH occasion configurations before the UE needs to transmit data. This allows the UE to immediately transmit multiple PDUs using the pre-configured resources without needing to transition to RRC connected state, thereby avoiding the power consumption and delay associated with state transitions.
3Ease of operation
If traditional PRACH resource configuration is used, then random access procedure is simple, but small data transmission flexibility is restricted
Solution Approach 1:
The patent makes the PRACH resource configuration multi-functional by creating a unified configuration structure that can handle both traditional random access and SDT scenarios. The SDT PRACH resource configuration includes fields for multiple preamble formats, multiple frequency resources, and multiple time resources, allowing the same configuration mechanism to serve both simple random access and flexible small data transmission needs without requiring separate dedicated resources for each case.
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.