User Terminal Contention-Based UL Transmission TA Timer Control
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Solution Overview
Problem
In future radio communication systems like 5G, the latency time before UL data is transmitted and the growth of overhead due to UL grants from radio base stations pose challenges, especially in accommodating high-speed, large-capacity communications and massive access scenarios such as mMTC, where contention-based random access procedures can lead to increased latency and overhead.
Innovation Solution
Implementing contention-based UL data transmission without UL grants from the radio base station, where the user terminal controls the timing of UL data transmission based on the running state of a timing advance (TA) timer, allowing for flexible configuration of transmission methods based on service type and QoS parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If random access procedures are performed before UL data transmission as in existing LTE systems, then UL synchronization is established, but latency time before UL data transmission increases
Solution Approach 1:
The system performs preliminary UL synchronization establishment through random access procedures before actual data transmission needs arise. The TA timer is started in advance during random access, and contention-based UL data transmission is enabled while the timer is running, allowing data to be transmitted without waiting for additional UL grants.
Solution Approach 2:
The patent extracts the UL grant requirement from the data transmission process. By allowing contention-based UL data transmission without UL grants while the TA timer is running, it separates the synchronization maintenance function (TA timer) from the resource allocation function (UL grants), reducing latency for urgent data transmission.
2Reliability
If random access procedures are performed before UL data transmission, then UL synchronization is established, but overhead due to UL grants from radio base stations increases
Solution Approach 1:
The patent removes the UL grant requirement from the data transmission process for the duration that UL synchronization is valid (while TA timer is running). This extracts the resource allocation overhead from each data transmission event, replacing it with a single synchronization establishment phase.
Solution Approach 2:
The user terminal autonomously determines whether contention-based UL data transmission is applicable by checking the TA timer state itself, without requiring the radio base station to allocate resources via UL grants. The terminal self-manages the transmission permission based on its own synchronization status.
3Loss of time
If contention-based UL data transmission is allowed without UL grants, then latency is reduced and overhead is reduced, but control of UL transmission timing becomes more complex
Solution Approach 1:
The system uses the TA timer as a feedback mechanism to control contention-based UL data transmission. The timer automatically expires when UL synchronization is no longer valid, providing a self-regulating feedback loop that controls transmission permissions without complex external intervention.
Solution Approach 2:
The patent introduces dynamic control of UL transmission permissions based on the running state of the TA timer. The ability to perform contention-based UL data transmission changes dynamically - enabled when the timer is running, disabled when expired - allowing flexible adaptation to synchronization status without static complex scheduling.
Data Source
AI summary
The present invention is designed to provide a user terminal and a radio communication method, whereby the period to apply contention-based UL data transmission can be configured adequately. A user terminal according to the present invention has a transmission section that transmits UL data to a radio base station, and a control section that controls application of contention-based UL data transmission in which UL data is transmitted without a UL grant from the radio base station, and the control section controls whether or not to apply the contention-based UL data transmission based on a running state of a timing advance (TA) timer.