Packet-Based D2D Discovery in LTE Networks
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Solution Overview
Problem
Current LTE networks face challenges in device discovery for direct device-to-device (D2D) communication, particularly in signaling and conveying discovery information effectively within and outside network coverage.
Innovation Solution
The implementation of a packet-based D2D discovery method using a Physical ProSe Discovery Channel (PPDCH) with a discovery packet that includes a payload and CRC, transmitted by UEs within allocated discovery resources, allowing for efficient sharing of discovery-related content between devices, even in scenarios without network coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a packet-based discovery method is used to convey discovery information, then the completeness and flexibility of discovery information sharing is improved, but the signaling overhead and processing complexity increase
Solution Approach 1:
The discovery information is segmented into a discovery packet structure with distinct fields including a header portion and a payload portion. The header contains metadata such as payload size and modulation and coding scheme (MCS) indicators, while the payload carries the actual discovery information. This segmentation allows receiving UEs to efficiently parse and process only the necessary information based on the header indicators, reducing overall processing complexity while maintaining information completeness.
Solution Approach 2:
The patent employs variable payload sizes and multiple modulation and coding schemes (MCS) to adapt the discovery packet to different channel conditions and information requirements. By dynamically changing these parameters based on channel quality and discovery needs, the system achieves flexible information transmission without requiring fixed complex signaling structures for all scenarios.
2Adaptability or versatility
If D2D discovery is enabled outside network coverage, then the versatility and coverage of D2D communication is improved, but the coordination and synchronization difficulty increases
Solution Approach 1:
The patent enables UEs to autonomously perform discovery operations without network coordination when outside network coverage. Each UE independently transmits and monitors discovery packets using pre-configured parameters and autonomous resource selection from available uplink resources. This self-service mechanism allows D2D discovery to function in standalone scenarios without requiring complex network-based synchronization infrastructure.
3Productivity
If discovery resources are allocated in uplink subframes with limited bandwidth, then the impact on cellular operations is reduced, but the discovery channel capacity is limited
Solution Approach 1:
The patent utilizes uplink resource blocks that are already allocated for cellular communications to also serve as discovery resources. By making these resources multi-functional, the system achieves D2D discovery capability without dedicating separate bandwidth specifically for discovery, thereby maintaining cellular operation efficiency while providing sufficient discovery channel capacity through efficient resource sharing.
Solution Approach 2:
The discovery packets are transmitted periodically in configured uplink subframes, allowing UEs to perform discovery operations at regular intervals without requiring continuous dedicated discovery resources. This periodic transmission approach enables efficient use of limited uplink bandwidth while maintaining effective discovery coverage through repeated opportunities for packet transmission and reception.
Data Source
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AI summary
Embodiments of a User Equipment (UE) and methods for packet based device-to-device (D2D) discovery in an LTE network are generally described herein. In some embodiments, UE may be enabled for proximity services and may be configured to receive signaling from an enhanced node B (eNB) indicating resources allocated for D2D discovery. The UE may configure a discovery packet in accordance with a predetermined configuration to have at least a discovery payload and a cyclic-redundancy check (CRC). The discovery payload may include discovery-related content. The UE may be configured to transmit the discovery packet on at least some of the indicated resources for receipt by a receiving UE. In some embodiments, a demodulation reference signal (DMRS) may be selected to indicate a payload size and/or MCS of the discovery packet's payload.