N-Hop D2D Synchronization Signal Selection via RSRP Threshold
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Solution Overview
Problem
Existing N-hop synchronous networks for D2D communication face challenges in synchronizing a large quantity of UEs outside network coverage, leading to energy inefficiencies and D2DSS contamination due to excessive SYN sources, and require mechanisms like RSRP Threshold and Cluster Head Muting, which can cause time differences and increase CP length beyond current LTE and LTE-A systems.
Innovation Solution
A method where UEs detect and select synchronization signals from nearby SYN sources based on hop count and RSRP, operating as SYN sources only if the RSRP does not exceed a predefined threshold, and utilizing these signals to synchronize and extend network coverage, thereby minimizing the number of SYN sources and reducing propagation delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all UEs are allowed to act as SYN sources to provide synchronization coverage, then synchronization coverage is improved, but energy consumption increases and D2DSS contamination occurs
Solution Approach 1:
The patent changes the parameter of SYN source activation from binary (all UEs or none) to conditional based on RSRP threshold. UEs only act as SYN sources when the received RSRP from other SYN sources falls below a predefined threshold, thereby reducing unnecessary energy consumption while maintaining synchronization coverage where needed.
Solution Approach 2:
The system enables UEs to autonomously determine whether to act as SYN sources based on local RSRP measurements. Each UE independently evaluates the signal strength from existing SYN sources and decides whether to activate its own synchronization signal transmission, eliminating the need for centralized control and reducing overall energy consumption.
2Use of energy by moving object
If RSRP Threshold and Cluster Head Muting mechanisms are applied to reduce SYN sources, then energy consumption is reduced, but time differences increase and CP length must be extended
Solution Approach 1:
The patent adjusts the RSRP threshold parameter dynamically or optimizes its value to balance between reducing the number of SYN sources (lowering energy consumption) and maintaining acceptable time synchronization. By carefully selecting the threshold level, the system reduces unnecessary SYN source activations while keeping propagation time differences within manageable limits that do not require excessive CP extensions.
3Reliability
If multiple SYN sources are activated to cover UEs outside network coverage, then synchronization availability is improved, but D2DSS contamination occurs
Solution Approach 1:
The patent uses RSRP threshold as a control parameter to regulate SYN source activation. When RSRP from existing SYN sources is above the threshold, new SYN source activation is prevented, avoiding D2DSS contamination. When RSRP falls below the threshold, SYN source activation is permitted, ensuring synchronization availability while preventing harmful interference.
Solution Approach 2:
The system implements feedback through RSRP measurements where UEs continuously monitor the signal strength from existing SYN sources. This feedback mechanism allows the network to dynamically adjust SYN source activation decisions, ensuring that new SYN sources are only activated when truly necessary, thereby preventing D2DSS contamination while maintaining synchronization availability.
Data Source
AI summary
The disclosure proposes a method of forming an N-hop synchronous network for D2D communication and devices using the same. In one of the exemplary embodiments, the method may include detecting one or more synchronization signals which are transmitted from one or more nearby synchronization sources; selecting, from the one or more synchronization signals, a first SS transmitted from a neighboring synchronization source having a hop count=i, wherein i is the smallest hop count detected from the one or more neighboring synchronization sources; and if there are more than one neighboring synchronization sources with hop count=i, the first SS is selected as having a maximum RSRP detected by the UE; and if the RSRP of the first SS does not exceeds a predefined threshold: operating as a synchronization source; and transmitting a SS based on the first SS.