V2X Transmission Timing Offset Compensation
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Solution Overview
Problem
The existing 3GPP standard is not suitable for vehicle-to-vehicle (V2V) communication due to synchronization with a base station's downlink subframe sync signal, which is inadequate for vehicles in shadow areas or out of coverage, leading to interference and timing errors.
Innovation Solution
A method using satellite signals, such as GNSS, for time synchronization in V2V communication, where a vehicle receives timing offsets from a base station to determine transmission timing, adjusting for both satellite and reference cell synchronization, and transmitting signals based on these offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If time synchronization is based on base station downlink sync signal, then synchronization is achieved in coverage area, but vehicles in shadow areas or out of coverage experience timing errors and interference
Solution Approach 1:
The patent introduces satellite signals as an intermediary synchronization source. When base station signals are unavailable (out of coverage or shadow areas), vehicles use satellite-based timing as a mediator to maintain synchronization, thus resolving the contradiction between reliable synchronization and coverage adaptability
Solution Approach 2:
The patent implements dynamic synchronization source selection. Vehicles can switch between base station-based synchronization (when available) and satellite-based synchronization (when base station is unavailable), making the synchronization system adaptive to different coverage conditions and resolving the contradiction
2Adaptability or versatility
If satellite signals are used for time synchronization, then coverage adaptability is improved for out-of-coverage vehicles, but timing accuracy may be affected without proper offset compensation
Solution Approach 1:
The patent applies preliminary offset compensation. The base station calculates timing offsets between satellite-based timing and base station timing in advance and provides these offsets to vehicles. This preliminary action ensures that when vehicles use satellite signals, the timing accuracy is maintained by pre-compensating for known differences
Solution Approach 2:
The patent implements feedback through timing offset information. The base station measures and determines the timing offset between satellite synchronization and base station synchronization, then feeds this offset information back to vehicles. Vehicles use this feedback to adjust their transmission timing, maintaining accuracy while using satellite signals
3Device complexity
If vehicles transmit based on satellite-derived timing without offset adjustment, then simplicity is maintained, but interference increases due to timing misalignment with base station uplink
Solution Approach 1:
The base station provides feedback in the form of timing offset information to vehicles. This feedback enables vehicles to adjust their transmission timing to align with base station uplink timing, preventing interference while maintaining relatively simple vehicle-side implementation
Solution Approach 2:
The patent changes the timing parameter of vehicle transmissions based on received offset information. Vehicles adjust their transmission timing parameter to compensate for the difference between satellite-based timing and base station timing, thereby eliminating interference while keeping the vehicle device complexity low
Data Source
AI summary
There is provided a method for determining transmission timing. The method may be performed by a terminal and comprise: receiving information on a first timing offset between a signal of a base station and a signal of a satellite and information on a reference cell; performing a time synchronization based on the signal of the satellite; and determining transmission timing based on the first timing offset and a second timing offset for the reference cell.