D2D Synchronization Signal Root Index Segmentation
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Solution Overview
Problem
Current wireless communication systems, such as LTE, face challenges in efficiently transmitting synchronization signals for device-to-device (D2D) communication, particularly in reducing interference and optimizing resource utilization for synchronization signal detection.
Innovation Solution
A method involving the detection of a first and second synchronization signal in specific subframes, where the signals are generated based on different root index sets, with the second signal potentially located at a slot boundary or transition symbol, and used for time or frequency domain synchronization, allowing for efficient detection and reduced interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single synchronization signal is transmitted in D2D communication, then the transmission structure is simple, but interference between different D2D links increases and detection reliability deteriorates
Solution Approach 1:
The synchronization signal is segmented into two distinct parts: first synchronization signal (P-Sync) and second synchronization signal (S-Sync). These segments are transmitted in different subframes using different root indices, allowing receivers to detect and combine information from both segments to achieve more reliable synchronization while maintaining manageable system complexity through structured segmentation.
Solution Approach 2:
Different root indices are assigned to different synchronization signal segments and different D2D links. This local differentiation in the root index domain creates orthogonal or near-orthogonal signatures for different links, reducing mutual interference while keeping the overall transmission structure relatively simple and enabling reliable detection through localized signal characteristics.
2Object-affected harmful factors
If multiple root indices are used for synchronization signals, then interference between D2D links is reduced, but the complexity of signal generation and detection increases
Solution Approach 1:
The patent employs periodic transmission of synchronization signals with different root indices in an alternating pattern. First synchronization signal uses one root index in odd subframes, while second synchronization signal uses another root index in even subframes. This periodic alternation reduces inter-link interference through time-division multiplexing of root indices, while the regular pattern keeps detection complexity manageable through predictable timing.
Solution Approach 2:
Instead of using the same root index for all synchronization signals and relying on other dimensions for differentiation, the patent inverts the approach by making root index the primary differentiation dimension. Different root indices are assigned to different synchronization signal types and D2D links, fundamentally changing how interference is managed and simplifying the overall system by leveraging the inherent orthogonality of Zadoff-Chu sequences with different root indices.
3Speed
If synchronization signals are transmitted in every subframe, then detection speed is improved, but resource utilization deteriorates and energy consumption increases
Solution Approach 1:
Synchronization signals are transmitted periodically rather than continuously in every subframe. The first and second synchronization signals are transmitted in alternating subframes with specific periodicity, reducing the total number of transmissions while maintaining adequate detection speed. This periodic transmission pattern optimizes the balance between detection speed and resource consumption by transmitting only when necessary.
Solution Approach 2:
The synchronization transmission is segmented into two separate signal types transmitted in different subframes. This segmentation allows the system to distribute synchronization transmissions over time rather than concentrating them, improving detection reliability through diversity while reducing overall resource consumption compared to transmitting a single strong signal in every subframe.
4Device complexity
If a single root index is used for all synchronization signals, then device complexity is reduced, but interference between different D2D communication links increases
Solution Approach 1:
Different root indices are assigned to different synchronization signal segments and different D2D links locally. This local differentiation creates orthogonal signatures for different links in the root index domain, reducing mutual interference. The local quality approach maintains simple overall device architecture while achieving interference reduction through localized parameter differentiation.
Solution Approach 2:
The patent inverts the conventional approach by making root index differentiation the primary mechanism for interference management rather than relying on other dimensions like time or frequency resources. By assigning different root indices to different synchronization signals and D2D links, the system fundamentally reduces interference at the signal generation level, simplifying subsequent processing while effectively managing inter-link interference.
Data Source
AI summary
The present invention relates to a method of detecting a synchronization signal for D2D (device to device) communication of a terminal in a wireless communication system. More particularly, the method includes detecting a first synchronization signal and a second synchronization signal on a specific sub-frame for a synchronization signal period set for D2D communication, wherein the first synchronization signal is generated based on a first of predefined sets of root indexes, the second synchronization signal is generated based on a second of predefined sets of root indexes, and the first set of root indexes and the second set of root indexes are made up of different indexes.