D2D Synchronization Using Network Timing Reference and Offset
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Solution Overview
Problem
In Device-to-Device (D2D) communication, RRC_IDLE wireless devices lack timing information for receiving data from other devices due to propagation delays, leading to potential reception failures and interference with cellular communications.
Innovation Solution
A method where a first wireless device obtains a timing reference and time offset from a wireless network and transmits a Scheduling Assignment (SA) to a second wireless device, allowing it to synchronize its reception timing for D2D communication, even when in idle mode, thereby reducing interference and enabling inter-cell D2D communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If RRC_IDLE wireless devices perform D2D communication without timing synchronization, then device complexity is reduced and ease of operation is improved, but reception reliability deteriorates due to propagation delays causing timing misalignment
Solution Approach 1:
The patent introduces a timing reference obtained from cellular network synchronization signals as an intermediary. This timing reference acts as a mediator between the unsynchronized D2D devices, allowing them to align their reception timing without requiring complex direct synchronization protocols between idle devices.
Solution Approach 2:
The patent makes the cellular network's timing synchronization mechanism serve multiple functions: it synchronizes both cellular communications and D2D communications. By using the same timing reference for both purposes, the system avoids creating a separate synchronization infrastructure for D2D.
2Reliability
If D2D devices synchronize using cellular network timing references, then reception timing accuracy is improved, but interference with cellular communications increases due to timing conflicts
Solution Approach 1:
The patent changes the timing parameters for D2D transmissions by applying a timing offset to the cellular network's timing reference. This offset shifts D2D transmission times to avoid conflicts with cellular uplink and downlink slots, thereby reducing interference while maintaining synchronization accuracy.
3Adaptability or versatility
If D2D communication operates independently without network timing reference, then device autonomy is improved and network resource usage is reduced, but timing synchronization between devices deteriorates
Solution Approach 1:
The cellular network's timing synchronization signals serve as a common intermediary reference that both D2D devices can independently access. This allows autonomous operation without direct device-to-device coordination while ensuring timing alignment through the shared network reference.
4Reliability
If timing advance is applied for propagation delay compensation, then reception timing accuracy is improved, but device complexity increases due to additional timing adjustment mechanisms
Solution Approach 1:
The patent enables idle devices to autonomously obtain and apply timing references and offsets without requiring complex interaction with the network or other devices. The device independently performs timing synchronization by acquiring network references and applying appropriate offsets, simplifying the overall system while maintaining accuracy.
Data Source
AI summary
A first and a second wireless device and a respective method performed thereby for enabling D2D communication there between are provided. The method performed by the first wireless device comprises obtaining a timing reference and a time offset, from a wireless network; and transmitting, to the at least one second wireless device, an SA in accordance with the obtained timing reference, the SA comprising the time offset. The method further comprises transmitting data, to the at least one second wireless device, in accordance with an uplink timing, wherein the uplink timing is based on the time offset and the timing reference.