5G NR Time Alignment Timer Handling During Beam Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing 5G NR systems face challenges in handling significant jumps in propagation delay during beam switching between non-collocated remote radio heads, leading to misaligned uplink timing and data transmission interruptions, particularly in high-speed train scenarios at high frequencies.
Innovation Solution
Implement a mechanism to stop the timeAlignmentTimer without flushing HARQ buffers and automatically trigger a random access preamble when uplink timing is not aligned, allowing for immediate adjustment of uplink timing through pre-configured RACH resources and network assistance signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If beam switching between non-collocated remote radio heads is performed, then network coverage and capacity are improved, but uplink timing alignment is lost causing data transmission interruptions
Solution Approach 1:
The system performs preliminary actions by stopping the timeAlignmentTimer before beam switching and automatically triggering a random access preamble to reacquire timing alignment. This preliminary timing adjustment ensures that uplink synchronization is restored quickly after beam switching, preventing data transmission interruptions while maintaining the adaptability of beam switching operations.
2Loss of time
If timeAlignmentTimer is stopped and random access preamble is triggered, then uplink timing alignment is restored quickly, but HARQ buffer flushing occurs causing data loss
Solution Approach 1:
The invention extracts the timing alignment restoration function from the traditional timeAlignmentTimer mechanism and implements it through a separate automatic random access preamble trigger. This separation allows the system to restore uplink timing alignment quickly without necessarily flushing HARQ buffers, as the timing adjustment can be performed independently of the buffer management process.
3Reliability
If traditional timing alignment procedure is used after beam switching, then uplink timing is realigned, but data transmission is interrupted due to buffer flushing
Solution Approach 1:
The system implements self-service by automatically detecting timing alignment status and triggering random access preamble transmission without requiring network intervention or HARQ buffer flushing. This autonomous timing recovery mechanism maintains uplink synchronization while preserving data transmission continuity, as the user equipment can independently restore timing alignment without interrupting the data flow.
Data Source
AI summary
Systems, methods, apparatuses, and computer program products for enhanced handling time alignment timer at transmission configuration indicator state switch are provided. For example, a method can include performing a transmission configuration indicator state switch to a network element. The method can also include determining whether an uplink timing is aligned with respect to the network element. The method can further include determining whether a random access channel procedure is needed to adjust uplink timing in response to the determining that the uplink timing is not aligned. The method can additionally include adjusting the uplink transmit timing in response to a result of the determining whether random access channel procedure is needed to adjust uplink timing.