D2D Relay for Out-of-Cell Synchronization
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Solution Overview
Problem
Devices located outside a cellular region face challenges in participating in device-to-device (D2D) communication within a cellular system, particularly in obtaining synchronization and performing authentication, which hinders efficient D2D communication.
Innovation Solution
A method and apparatus that allow a device outside a cellular region to obtain synchronization and authentication information through another device within the cellular region, enabling it to participate in the D2D communication process by transmitting and receiving necessary signals and resources, such as RACH and RAR information, and performing authentication procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a device located outside a cellular region attempts to participate in D2D communication, then the device can extend the coverage and enable communication in remote areas, but the device cannot obtain synchronization and authentication information from the base station directly
Solution Approach 1:
The patent introduces an intermediate device (relay device) that acts as a mediator between the out-of-coverage device and the base station. The relay device receives synchronization and authentication information from the base station and forwards it to the out-of-coverage device, enabling the device to participate in D2D communication without direct base station contact.
Solution Approach 2:
The relay device performs preliminary actions by obtaining synchronization and authentication information from the base station in advance, before the out-of-coverage device needs to communicate. This preliminary acquisition of critical information enables the out-of-coverage device to quickly join the D2D communication without attempting direct base station connection.
2Productivity
If D2D communication uses direct device-to-device transmission, then radio resource efficiency is improved, but devices outside cellular regions cannot access necessary network resources
Solution Approach 1:
The relay device serves as an intermediary that bridges the gap between direct D2D communication and network access. It maintains the efficiency of direct device-to-device transmission while simultaneously providing the out-of-coverage device with network resources through the relay connection to the base station.
Solution Approach 2:
The relay device performs multiple functions: it acts as both a D2D communication participant (maintaining radio efficiency) and a network access gateway (providing connectivity to out-of-coverage devices). This multi-functionality resolves the contradiction between direct communication efficiency and network access capability.
3Reliability
If out-of-coverage devices use relay devices to obtain synchronization information, then synchronization reliability is improved, but the complexity of the communication protocol increases
Solution Approach 1:
The relay device autonomously handles the complexity of obtaining and managing synchronization and authentication information from the base station. The out-of-coverage device simply receives pre-packaged synchronization data from the relay without needing to implement complex base station communication protocols itself, thus maintaining simplicity while achieving reliability.
Data Source
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AI summary
According to an embodiment of this disclosure, a method for transmitting and receiving a signal in a device of a mobile communication system includes steps of receiving, from a base station, a first message containing one or more of synchronization information and resource allocation information; transmitting, to other device, a second message containing the received synchronization information and resource allocation information; and receiving, from the other device, a third message for a random access based on the synchronization information and the resource allocation information. According to an embodiment of the present disclosure, even a device failing to obtain synchronization can obtain synchronization from a base station through other device, receive authentication and security related information, and thereby perform reliable D2D communication. Also, a communication efficiency can be improved by transmitting and receiving D2D related information between devices through limited resources.