D2D Synchronization Signal Resource Allocation
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Solution Overview
Problem
In Device-to-Device (D2D) communication, interference from SRS or DM-RS signals sent by nearby UEs can cause synchronization failures and reduce the accuracy of time-frequency synchronization and channel estimation due to overlapping or non-overlapping frequency domain positions, leading to interference with the D2D Synchronization Signal (D2D SS).
Innovation Solution
A method where the source UE selects a ZC sequence from a set of predetermined sequences and maps it to a predefined D2D SS resource, reducing interference by performing cyclic shift expansion or punching, thereby minimizing mutual interference with SRS and DM-RS signals from target UEs, even in no-network coverage scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If D2D SS uses conventional frequency resources overlapping with SRS/DM-RS, then spectrum efficiency is improved, but synchronization accuracy deteriorates due to interference
Solution Approach 1:
The frequency domain resources are segmented into different regions: D2D SS uses first frequency domain resources while SRS/DM-RS use second frequency domain resources. This segmentation prevents overlap and interference, allowing D2D synchronization signals to be transmitted without degradation from uplink reference signals, thus maintaining synchronization accuracy while efficiently utilizing available spectrum resources.
Solution Approach 2:
The patent introduces frequency domain separation as an additional dimension for resource allocation. By assigning D2D SS and SRS/DM-RS to different frequency domains (first vs. second frequency domain resources), the system adds a dimensional separation that eliminates interference while maintaining spectral efficiency through structured resource partitioning.
2Quantity of substance
If D2D SS and SRS/DM-RS share the same time-frequency resources, then resource utilization is improved, but interference increases causing synchronization failures
Solution Approach 1:
Time-frequency resources are segmented into distinct allocation patterns: D2D SS transmissions use specific subframes and frequency resources that are separated from SRS/DM-RS resources. This segmentation allows both D2D synchronization and uplink reference signal operations to coexist without mutual interference, maintaining high resource utilization while eliminating harmful interference effects.
Solution Approach 2:
The patent introduces frequency domain separation as an intermediary mechanism between D2D SS and SRS/DM-RS signals. By placing an frequency domain boundary between these signal types, the system mediates their coexistence, allowing both to operate simultaneously without direct interference while maintaining efficient resource utilization.
3Reliability
If D2D SS transmission power is increased to overcome interference, then synchronization reliability is improved, but energy consumption increases
Solution Approach 1:
The patent converts the potential harm of frequency overlap into benefit by using frequency domain separation. Instead of increasing power to overcome interference, the system restructures resource allocation so that D2D SS and SRS/DM-RS operate in separate frequency domains. This eliminates the need for high power transmission while maintaining synchronization reliability, thus reducing energy consumption without sacrificing performance.
Data Source
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AI summary
Provided are a method and apparatus for sending a Device-to-Device Synchronization Signal (D2D SS), and a User Equipment (UE). The method includes that: a source UE selects one Zadoff-Chu (ZC) sequence from M predetermined ZC sequences of which a length is N; the source UE maps the selected ZC sequence to a predefined D2D SS source; and the source UE sends a D2D SS obtained after the mapping to a target UE. By means of the technical solution, mutual interferences between a Demodulation-Reference Signal (DM-RS) and a Sounding Reference Signal (SRS) sent by the target UE and the D2D SS can be effectively reduced.