D2D Reference Signal Generation Using Time-Varying IDs
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Solution Overview
Problem
In device-to-device (D2D) communication, existing methods face challenges in avoiding collisions between user equipment (UEs) and optimizing resource utilization, particularly in generating reference signals that efficiently manage interference and synchronization.
Innovation Solution
A method is introduced to generate a reference signal with an ID that changes over time, using a sequence index and cyclic shift index determined by the D2D UE identity, which helps in minimizing interference by randomizing the DMRS sequence and scrambling sequence used on D2D channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed ID is used for generating reference signals in D2D communication, then the reference signal generation is simple, but collisions between D2D UEs occur and resource utilization efficiency deteriorates
Solution Approach 1:
The patent applies dynamics by making the reference signal generation parameters (sequence index and cyclic shift index) time-varying instead of fixed. The UE identity is combined with time information (subframe index, slot index, or symbol index) to generate different reference signal sequences at different time instances, thereby avoiding collisions while maintaining manageable complexity
Solution Approach 2:
The patent changes the parameters used for reference signal generation from static UE ID to dynamic composite parameters including UE ID plus time information. By modifying the sequence index and cyclic shift index based on time-varying parameters, the system achieves better collision avoidance without significantly increasing generation complexity
2Reliability
If a time-varying ID is used for generating reference signals, then collision avoidance between D2D UEs is improved, but the device complexity for signal generation increases
Solution Approach 1:
The patent implements dynamics by introducing time-varying parameters (subframe index, slot index, or symbol index) into the reference signal generation process. This dynamic approach allows UEs to generate unique reference signals at different time instances, improving collision avoidance while keeping the complexity increase manageable through standardized time indexing
Solution Approach 2:
The patent modifies the generation parameters from static to dynamic by combining UE identity with time information. The sequence index and cyclic shift index are derived from composite parameters that include time variables, achieving better reliability without excessive complexity through systematic parameter transformation
3Productivity
If unique DMRS sequences are assigned to each D2D UE, then resource utilization efficiency is enhanced, but the system complexity for sequence management increases
Solution Approach 1:
The patent applies universality by using a common generation formula that works for all D2D UEs. The same time-varying parameter mechanism is universally applied across all UEs to generate unique sequences, achieving high resource utilization efficiency while keeping sequence management complexity manageable through standardized procedures
Solution Approach 2:
The patent uses parameter changes to differentiate sequences across UEs and time instances. By systematically varying the sequence index and cyclic shift index based on UE identity and time information, the system achieves unique sequence assignment for each UE without requiring complex manual management, thereby enhancing resource utilization efficiency
Data Source
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Figure 2
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AI summary
According to one embodiment of the present invention, a method of transmitting a D2D (device-to-device) signal, which is transmitted by a user equipment in a wireless communication system, comprising the steps of determining a sequence group, determining a base sequence in the sequence group, generating a reference signal sequence by applying cyclic shift to the base sequence, generating a demodulation reference signal sequence from the reference signal sequence and transmitting a subframe to which the demodulation reference signal sequence is mapped, wherein ID information, which is used for at least one selected from the group consisting of determination of the sequence group, determination of the base sequence and application of the cyclic shift, corresponds to one of an SSID (synchronization ID) and an L1 ID (layer 1 ID) changing according to time.