RACH Preamble Transmission Timing Offset for Wireless Slot Alignment
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Solution Overview
Problem
In wireless communications, the inaccuracy in estimating system timing and propagation delay for Random Access Channel (RACH) preamble transmission can lead to interference with previous slot communications, as the RACH preamble may arrive either before or after the slot boundary, causing inefficiencies and resource misallocation.
Innovation Solution
Implementing a timing offset for RACH preamble transmission, based on a system-wide parameter or pre-configured value, to adjust the transmission timing, ensuring the RACH preamble arrives at or after the slot boundary, thereby avoiding interference with previous slot communications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RACH preamble transmission timing is based on estimated propagation delay and system timing, then the transmission can be initiated without waiting for precise timing information, but the RACH preamble may arrive before or after the slot boundary causing interference with previous slot communications
Solution Approach 1:
The base station pre-configures the UE with a timing offset value before the UE transmits the RACH preamble. This preliminary timing adjustment ensures that when the UE transmits the RACH preamble based on its estimated propagation delay and system timing, the preamble will arrive at the base station at or after the slot boundary, avoiding interference with previous slot communications while maintaining fast access
2Loss of time
If the RACH preamble is transmitted immediately based on available timing estimates, then access latency is reduced, but timing inaccuracy causes the preamble to arrive outside the intended reception window
Solution Approach 1:
The patent introduces a timing offset parameter that is pre-configured by the base station and applied by the UE to adjust its RACH preamble transmission timing. This parameter modification allows the UE to compensate for timing estimation inaccuracies and propagation delay variations, ensuring that the RACH preamble arrives at the base station within the correct reception window while maintaining low access latency
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. In some systems, a user equipment (UE) may account for propagation delay when initiating a random access (RACH) procedure. For example, the UE may determine transmission timing for a RACH preamble based on an estimated propagation delay, such that the RACH preamble is received at a base station approximately at the beginning of a slot. To support reliable communication of the RACH preamble, the UE may implement a timing offset. In some examples, the base station may configure the UE with the timing offset using system information. Alternatively, the UE may be pre-configured with the timing offset. By determining the transmission timing for the RACH preamble further based on the timing offset, the UE may ensure that the RACH preamble is received at the base station after a slot boundary (e.g., avoiding causing interference to communications in a previous slot).