D2D Timing Advance Adjustment for Cellular Multiplexing
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Solution Overview
Problem
Existing Device-to-Device (D2D) communication methods face challenges in multiplexing resources for D2D and cellular communications, leading to performance degradation due to timing synchronization issues between terminals in different cell coverage areas.
Innovation Solution
The method involves receiving a Timing Advance (TA) value from a base station, adjusting the TA value for D2D communication, and transmitting data using either the same or different Cyclic Prefix (CP) lengths for D2D and cellular communications, while including a timing adjustment step size in the Scheduling Assignment (SA) signal to ensure proper timing alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If resources for D2D communication and cellular communication are multiplexed, then resource utilization efficiency is improved, but timing synchronization between terminals in different cell coverage areas deteriorates
Solution Approach 1:
The patent applies local quality by allowing different timing advance values to be used for different communication types (D2D vs. cellular) and different coverage scenarios (in-coverage vs. out-of-coverage terminals). Specifically, in-coverage terminals use one timing advance value for cellular communication and a separate timing advance value for D2D communication, while out-of-coverage terminals use a default timing advance value for D2D communication. This localized differentiation resolves the timing synchronization issue while maintaining resource multiplexing efficiency.
Solution Approach 2:
The patent changes the timing advance parameter based on coverage status and communication type. The base station configures different timing advance values for in-coverage and out-of-coverage terminals, and adjusts these values dynamically based on the specific communication scenario (D2D or cellular). This parameter adaptation allows the system to maintain timing synchronization reliability while achieving high resource utilization through multiplexing.
2Measurement precision
If D2D data is transmitted at DL timing using first TA value, then timing alignment with base station is improved, but data reception quality at second terminal deteriorates due to propagation delay differences
Solution Approach 1:
The patent applies preliminary action by having the base station pre-configure different timing advance values for D2D communication before actual data transmission. The base station determines the appropriate timing advance value based on the terminal's coverage status and transmits this configuration in advance. This allows terminals to adjust their transmission timing beforehand, ensuring both timing alignment with the base station and proper synchronization between D2D terminals, thereby resolving the reception quality issue.
3Measurement precision
If different timing advance values are used for different cells, then timing accuracy for each cell is improved, but system complexity increases
Solution Approach 1:
The patent applies universality by designing a unified timing advance mechanism that handles both in-coverage and out-of-coverage scenarios through a single framework. The base station uses the same timing advance configuration procedure for all terminals, but adapts the specific values based on coverage status. This multi-functional approach maintains timing accuracy for different cells while avoiding the need for separate complex timing management systems, thus controlling overall system complexity.
Data Source
AI summary
A first terminal receives a first Timing Advance (TA) value from a base station and includes a second TA value that is obtained based on the first TA value in a Scheduling Assignment (SA) signal. The first terminal transmits the SA signal to a second terminal at downlink (DL) timing for receiving a downlink signal of the base station in cellular communication. When a length of a Cyclic Prefix (CP) that is set for the D2D communication and a length of a CP that is set for the cellular communication are different, the first terminal transmits data of the D2D communication to the second terminal at first timing that is obtained by applying the second TA value to the DL timing.