Measurement Gap Alignment for Cross-Cell D2D Discovery
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Solution Overview
Problem
In wireless communication networks, user equipment (UEs) at the cell edge face challenges in discovering other UEs for device-to-device (D2D) communications, especially when operating at low duty cycles to conserve power, making it difficult for UEs in different cells to find each other.
Innovation Solution
Configuring measurement gaps in one cell to overlap with discovery subframes of neighboring cells, using a set of allowed discovery cycles that include a minimum cycle and its integer multiples, allowing UEs to efficiently receive discovery messages from other UEs across different cells without disrupting existing communication patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If UE operates at low duty cycle to conserve power, then energy efficiency is improved, but ability to discover other UEs deteriorates
Solution Approach 1:
The network performs preliminary configuration of measurement gaps and discovery cycle alignment before D2D discovery is needed. The access node configures the UE with measurement gap patterns that are pre-aligned with neighbor cell discovery cycles, so when the UE needs to perform discovery, the timing is already prepared and no additional signaling is required.
Solution Approach 2:
The access node (eNodeB) acts as an intermediary between the UE and neighbor cells. It coordinates the measurement gap configuration with the neighbor cell's discovery cycle, effectively mediating the timing alignment so that the UE can receive discovery signals from neighbor cells during its measurement gaps without requiring continuous monitoring.
2Adaptability or versatility
If UE uses measurement gaps to receive discovery signals from neighbor cells, then cross-cell discovery capability is improved, but complexity of communication configuration deteriorates
Solution Approach 1:
The measurement gap configuration serves multiple functions: it enables the UE to receive discovery signals from neighbor cells, maintains alignment with existing network timing structures, and can be applied universally across different neighbor cells without requiring cell-specific configuration for each scenario.
Solution Approach 2:
The system changes the timing parameters of the UE's measurement gaps to align with neighbor cell discovery cycles. By adjusting the measurement gap offset and duration parameters, the configuration adapts to different neighbor cell scenarios while maintaining a standardized approach that reduces overall complexity.
Data Source
AI summary
A set of allowed discovery cycles is stored in a radio network access node, the set consisting of a minimum discovery cycle and integer multiples thereof and each discovery cycle defining only one interval for discovery. The access node transmits in a cell an indication of a specific discovery cycle selected from the set. The access node configures at least one user equipment in the cell with a measurement gap chosen to overlap a subframe for discovery within the one interval for discovery of a different discovery cycle of the set that is in use in a neighbor cell.