Relay Discovery in Cellular Networks via Centralized Base Station Selection
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Solution Overview
Problem
Current D2D LTE relay discovery mechanisms in cellular networks experience collisions and inefficient resource management, leading to suboptimal selection of relay devices, especially in scenarios with limited coverage or obstacles.
Innovation Solution
A method where the base station centrally manages the relay selection process by receiving requests on the random access channel with specific identifiers for both the relayed object and the relay device, allowing for efficient allocation of resources and avoiding collisions, using an extended RACH preamble that includes identifiers for the relayed device and the relay device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If candidate relay devices respond to relay requests using standardized discovery modes (Mode A or Mode B), then relay discovery is enabled, but collisions occur and resource management becomes inefficient
Solution Approach 1:
The base station acts as an intermediary that receives relay requests from connected objects and selects appropriate relay devices. Instead of allowing direct peer-to-peer discovery that causes collisions, the base station mediates the interaction by receiving requests on the random access channel and making centralized relay selection decisions, thereby eliminating collisions while maintaining discovery functionality
Solution Approach 2:
The relay selection process leverages the existing random access channel infrastructure that devices already use for other purposes. By reusing this established communication pathway for relay requests, the system enables relay discovery without requiring new dedicated resources, thus avoiding resource conflicts while maintaining reliability
2Adaptability or versatility
If multiple candidate relay devices respond simultaneously to relay requests, then more relay options are available, but resource management efficiency deteriorates due to collisions
Solution Approach 1:
The base station performs preliminary evaluation of relay requests before allocating resources. By receiving and processing multiple relay requests in advance through the random access channel, the base station can assess candidate devices and make informed selection decisions, maintaining adaptability while avoiding the efficiency loss from simultaneous responses and collisions
3Ease of operation
If relay devices are selected through decentralized competition among candidates, then device autonomy is maintained, but network resource optimization is compromised
Solution Approach 1:
The base station serves as a mediator that preserves device autonomy while enabling network-optimized relay selection. Devices can still indicate their relay capability and receive requests, maintaining operational autonomy, but the base station makes the final selection decision based on network conditions and resource availability, achieving both autonomy and optimization
Data Source
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Figure 6B~7B
AI summary
The invention relates in particular to an application method implemented by a device (UE) wishing to apply to relay data between an object (MTD) and a base station (gNB) in a cellular network, the object and the device (UE) being synchronised and connected with the base station. The device (UE) transmits (E10) a request, over a random-access channel (PRACH), for network resources in order to relay the data, the request comprising an identifier (ID_MTD) of the object. If the base station selects a device (UE1) from the candidate devices, it allocates network resources to the device and sends a positive response to the selected device.