D2D Synchronization Signal Mapping to Reduce LTE Interference
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Solution Overview
Problem
Existing LTE wireless communication systems lack an effective method for utilizing data resources to support Device-to-Device (D2D) communication, particularly in determining sequence mapping and scrambling schemes for synchronization signals.
Innovation Solution
The proposed solution involves configuring synchronization signals for D2D communication using new root indices and sequence mapping/scrambling schemes for PD2DSS and SD2DSS, which are generated based on different sequence sets depending on the active synchronization source being a BS or an ISS, and employing SC-FDM for signal waveforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional LTE data resources are used for D2D synchronization signal transmission, then resource utilization is limited, but interference during synchronization signal transmission increases
Solution Approach 1:
The patent applies parameter changes by introducing new root indices specifically for D2D synchronization signals and modifying sequence mapping schemes. This allows the system to differentiate D2D synchronization signals from conventional LTE data transmissions, reducing interference while improving resource utilization for D2D services
Solution Approach 2:
The patent segments the resource allocation by dedicating specific resources for D2D synchronization signal transmission separate from conventional LTE data resources. This segmentation is achieved through specific sequence mapping schemes that allocate distinct time-frequency resources, thereby reducing interference between different signal types
2Object-affected harmful factors
If new root indices and sequence mapping schemes are introduced for D2D synchronization signals, then interference is reduced, but device complexity increases
Solution Approach 1:
The patent applies local quality by introducing new root indices and sequence mapping schemes specifically for D2D synchronization signals while maintaining conventional LTE operations unchanged. This localized modification reduces interference for D2D communications without unnecessarily complicating the entire LTE system
Solution Approach 2:
The patent implements dynamic behavior by enabling User Equipments to adaptively select appropriate synchronization signal configurations based on their operational state (in-coverage or out-of-coverage). This dynamic adaptation allows the system to manage complexity efficiently by only activating D2D-specific features when needed
3Ease of operation
If D2D synchronization signals are transmitted without specific configuration, then device operation is simple, but information transfer capability is insufficient
Solution Approach 1:
The patent applies universality by designing D2D synchronization signals that simultaneously perform multiple functions: basic synchronization, source identification, and information transfer about duplex mode and coverage status. This multi-functionality is achieved through carefully designed sequence mapping schemes that embed additional information without complicating the transmission process
Solution Approach 2:
The patent implements preliminary action by pre-configuring specific sequence mapping schemes and root indices that encode information about synchronization source type and duplex mode. This preliminary configuration allows receiving UEs to decode essential information directly from the synchronization signals without requiring additional signaling overhead
Data Source
Figure 1(a)~1(c)
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AI summary
The present invention relates to a first user equipment, LTE, (140; 170; 850) comprising a processor, a radio frequency unit and a memory. The radio frequency unit is adapted to receive a device-to-device synchronization signal transmitted from a second LTE (130; 160; 800), wherein the device-to-device synchronization signal comprises a primary device-to-device synchronization signal and a secondary device-to-device synchronization signal, and wherein the secondary device-to-device synchronization signal is received via two symbols in a same subframe. The memory is configured for storing information for driving the processor. The first UE is configured to determine a root index of the primary device-to-device synchronization signal, to determine a sequence mapping and scrambling scheme for the secondary device-to-device synchronization signal, wherein the sequence mapping and scrambling scheme is used for each of the two symbols for the secondary device-to-device synchronization signal and to identify, based on the determined sequence mapping and scrambling scheme, information indicated through the secondary device-to-device synchronization signal, wherein the information indicated through the secondary device-to-device synchronization signal indicates one of two conditions.